Note: Descriptions are shown in the official language in which they were submitted.
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MAGNETICALLY-TRIGGERED PROXIMITY SWITCH
FIELD OF THE DISCLOSURE
[0001] This disclosure relates generally to proximity switches, and, more
particularly, to
miniature magnetically-triggered proximity switches.
BACKGROUND
[0002] Magnetic proximity switches, also known as limit switches, are commonly
used for
linear position sensing. Typically, magnetically-triggered proximity switches
include a
sensor that is adapted to detect the presence of a target without physically
contacting the
target. Typically, the sensor may include a switching circuit mechanism
enclosed within a
switch body, and the switching circuit mechanism typically includes multiple
levers and
contacts that are biased into a first position by one or more springs. When
the target, which
generally includes a permanent magnet contained within a housing, passes
within a
predetermined range of the sensor, the magnetic flux generated by the target
magnet triggers
the switching circuit mechanism, thereby closing a normally open circuit. The
closing of the
normally open circuit is detected by a processor, and a signal is sent to an
operator or an
automated operation system to indicate the presence of the target within the
predetermined
range of the sensor. The target is typically secured to a displaceable element
of a system,
such as a valve stem, and the sensor is typically secured to a stationary
element of a system,
such as a valve body. When so configured, the sensor can detect when the
displaceable
element has changed positions. However, due to the relatively large physical
size of the
sensor necessary to enclose the switching circuit mechanism, typical sensors
cannot be used
in applications requiring the placement of the sensor in an area having
limited free space. In
addition, the need to provide power to the sensor also limits the applications
in which the
sensor can be used.
[0003] While a relatively small magnetically-triggered proximity switch may be
desirable,
the ability to reduce the size of the proximity switch may be limited by
several factors.
Specifically, if relatively high load values are required in addition to
programmable logic
controller ("PLC") level loads of about 5V, correspondingly large contacts are
necessary to
accommodate the greater loads, and these large contacts limit the ability of
the switch to be
reduced in size. Additionally, as previously explained, there are numerous
components that
are disposed within the switch housing, and the size of the relatively complex
actuation
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assembly limits the minimum size of the switch. Such a complex actuation
assembly also
adds time and cost to the manufacturing of the proximity switch.
BRIEF SUMMARY OF THE DISCLOSURE
[0004] In accordance with one exemplary aspect of the present invention, a
magnetically-
triggered proximity switch includes a switch body and a first magnet non-
movably secured
within the switch body. A common arm having a first end and a second end is
also included,
and the second end is disposed within the switch body. The proximity switch
also includes a
primary arm having a first end and a second end. The second end is disposed
within the
switch body, and the second end includes a primary contact. In addition, the
proximity
switch includes a secondary arm having a first end and a second end. The
second end is
disposed within the switch body, and the second end also includes a secondary
contact. The
proximity switch also includes a cross arm disposed within the switch body.
The cross arm
has a first end and a second end, the first end being coupled to the common
arm and the
second end including a common contact. The proximity switch further includes a
second
magnet disposed within the switch body, and the second magnet is movable
relative to the
first magnet. The second magnet is coupled to the cross arm such that movement
of the
second magnet causes a corresponding movement of the cross arm between a first
switch
position and a second switch position. In the first switch position, the
common contact of the
cross arm is in contact with the primary contact of the primary arm, thereby
completing a
circuit between the common arm and the primary arm. In the second switch
position, the
common contact of the cross arm is in contact with the secondary contact of
the secondary
arm, thereby completing a circuit between the common arm and the secondary
arm.
[0005] In another embodiment, the first magnet and the second magnet are
selected to
create a first magnetic force between the first magnet and the second magnet,
and the first
magnetic force maintains the cross arm in the first switch position. In
addition, the second
magnet and a target outside of the switch body are selected to create a second
magnetic force
between the second magnet and the target, and the second magnetic force causes
the cross
arm to move from the first switch position to the second switch position if
the second
magnetic force is greater than the first magnetic force.
[0006] In a further embodiment, when the second magnetic force between the
target and
the second magnet becomes weaker than the first magnetic force between the
first magnet
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and the second magnet, the first magnetic force causes the cross arm to move
from the second
switch position to the first switch position.
[0007] In a still further embodiment, the first end of the cross arm is
pivotably coupled to
the second end of the common arm, and the movement of the second magnet
relative to the
first magnet causes the cross arm to rotate from the first switch position to
the second switch
position or from the second switch position to the first switch position. In
addition, an
elongated actuator arm may couple the second magnet to the common arm. The
actuator
arm may further be disposed within an aperture formed in the first magnet.
[0008] In another embodiment, the first end of each of the common arm, the
primary arm,
and the secondary arm is disposed outside of the switch body. In addition, the
switch body
may be cylindrical, and may be comprised of a high-temperature material.
Moreover, the
switch body may be comprised of plastic, and the switch body may be
hermetically sealed.
[0009] In accordance with another exemplary aspect of the present invention, a
method of
detecting a target by a magnetically-triggered proximity switch includes
providing a switch
body and disposing a second end of a common arm within the switch body. In
addition, a
primary contact of a primary arm is disposed within the switch body, and a
secondary contact
of a secondary arm is disposed within the switch body. The method also
includes movably
coupling a cross arm having a common contact to the common arm and coupling a
second
magnet to the common arm. A stationary first magnet is positioned within the
switch body
adjacent to the second magnet, and the common contact of the cross arm is
biased into
contact with the primary contact by the force of the first magnet acting on
the second magnet.
The method further includes positioning a target at a first location outside
of the switch body
such that the magnetic force between the target and the second magnet is
greater than the
magnetic force between the first magnet and the second magnet, thereby moving
the cross
arm such that the common contact disengages from the primary contact and
engages with the
secondary contact.
[0010] In another embodiment, the method also includes positioning the target
at a second
location outside of the switch body such that the magnetic force between the
target and the
second magnet is less than the magnetic force between the first magnet and the
second
magnet, thereby moving the cross arm such that the common contact disengages
from the
secondary contact and engages with the primary contact.
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[0011] In a further embodiment, the cross arm is pivotally coupled to the
second end of the
common arm such that the cross arm pivots to disengage the common contact from
the
primary contact and to engage the common contact with the secondary contact.
[0012] In a still further embodiment, when the common contact engages the
primary
contact, a closed circuit is formed between the common arm and the primary
arm, and when
the common contact engages the secondary contact, a closed circuit is formed
between the
common arm and the secondary arm.
[0013] In an additional embodiment, the method includes disposing a first end
of each of
the common arm, the primary arm, and the secondary arm outside of the switch
body. In
addition, the method may include hermetically sealing the switch body.
[0014] In accordance with a further exemplary aspect of the present invention,
a
magnetically-triggered proximity switch includes a switch body extending along
a body
longitudinal axis and a bias member non-movably secured within the switch
body. The
magnetically-triggered proximity switch also includes a first normally-closed
contact having
an engagement arm, a second normally-closed contact having an engagement arm,
a first
normally-open contact having an engagement arm, and a second normally-open
contact
having an engagement arm. The magnetically-triggered proximity switch further
includes a
contact magnet disposed within the switch body, the contact magnet being
movable relative
to the bias member such that the contact magnet is movable between a first
switch position
and a second switch position. In the first switch position, the contact magnet
contacts a
portion of the engagement arm of the first normally-closed contact and a
portion of the
engagement arm of the second normally-closed contact, thereby completing a
circuit between
the first normally-closed contact and the second normally-closed contact. In
the second
switch position, the contact magnet contacts a portion of the engagement arm
of the first
normally-open contact and a portion of the engagement arm of the second
normally-open
contact, thereby completing a circuit between the first normally-open contact
and the second
normally-open contact.
[0015] In accordance with another exemplary aspect of the present invention, a
method of
detecting a target by a magnetically-triggered proximity switch includes
providing a switch
body and disposing a pair of normally-closed contacts within the switch body
and disposing a
pair of normally-open contacts within the switch body. The method also
includes positioning
a stationary bias member within the switch body, movably disposing a contact
magnet
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adjacent to the bias member, and biasing the contact magnet into engagement
with the pair of
normally-closed contacts by the force of the bias member acting on the contact
magnet. The
method further includes positioning a target at a first location outside of
the switch body such
that the magnetic force between the target and the contact magnet is greater
than the magnetic
force between the bias member and the contact magnet, thereby moving the
contact magnet
out of engagement with the pair of normally-closed contacts and into
engagement with the
pair of normally-open contacts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1A is a top semi-sectional view of an embodiment of a
magnetically-
triggered proximity switch;
[0017] Figure 1B is a side view of the embodiment of Figure 1A;
[0018] Figure 1C is a rear view of the embodiment of Figure 1A;
[0019] Figure 2 is an exploded perspective view of an embodiment of a
magnetically-
triggered proximity switch;
[0020] Figure 3 is perspective view of an embodiment of a magnetically-
triggered
proximity switch;
[0021] Figure 4 is top view of a first body half of an embodiment of a
magnetically-
triggered proximity switch;
[0022] Figure 5A is perspective view of a common arm of an embodiment of a
magnetically-triggered proximity switch;
[0023] Figure 5B is perspective view of a cross arm of an embodiment of a
magnetically-
triggered proximity switch;
[0024] Figure 6A is semi-sectional view of an embodiment of a magnetically-
triggered
proximity switch in a first switch position;
[0025] Figure 6B is semi-sectional view of an embodiment of a magnetically-
triggered
proximity switch in a second switch position;
[0026] Figure 7A is an exploded perspective view of an embodiment of a
magnetically-
triggered proximity switch;
[0027] Figure 7B is a perspective view of the embodiment of Figure 7A;
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[0028] Figure 8A is a side view of the embodiment of Figure 7A;
[0029] Figure 8B is a rear view of the embodiment of Figure 7A;
[0030] Figure 9A is a sectional view of the embodiment of Figure 8A taken
along line 9A,
9B-9A, 9B illustrating the magnetically-triggered proximity switch in a first
switch position;
[0031] Figure 9B is a sectional view of the embodiment of Figure 8A taken
along line 9A,
9B-9A, 9B illustrating the magnetically-triggered proximity switch in a second
switch
position; and
[0032] Figure 10 is a top view of first body half of the switch body of the
embodiment of
Figure 7A.
DETAILED DESCRIPTION
[0033] As illustrated in Figure 1A, a magnetically-triggered proximity switch
10 includes a
switch body 12 and a first magnet 14 non-movably secured within the switch
body 12. The
proximity switch 10 also includes a common arm 16 having a first end 18 and a
second end
20, and the second end 20 of the common arm 16 is disposed within the switch
body 12. The
proximity switch 10 further includes a primary arm 22 having a first end 24
and a second end
26. The second end 26 is disposed within the switch body 12, and the second
end 26 includes
a primary contact 28. In addition, the proximity switch includes a secondary
arm 30 having a
first end 32 and a second end 34. The second end 34 is disposed within the
switch body 12,
and the second end 34 includes a secondary contact 36. A cross arm 38 is
disposed within
the switch body 12, and the cross arm 38 has a first end 40 and a second end
42. The first
end 40 is coupled to the common arm 16 and the second end 42 includes a common
contact
44. A second magnet 46 is disposed within the switch body 12, and the second
magnet 46 is
movable relative to the first magnet 14. Specifically, the second magnet 46 is
coupled to the
cross arm 38 such that movement of the second magnet 46 causes a corresponding
movement
of the cross arm 38 between a first switch position and a second switch
position. In the first
switch position, illustrated in Figure 6A, the common contact 44 of the cross
arm 38 is in
contact with the primary contact 28 of the primary arm 22, thereby completing
a circuit
between the common arm 16 and the primary arm 22. In the second switch
position, shown
in Figure 6B, the common contact 44 of the cross arm 38 is in contact with the
secondary
contact 36 of the secondary arm 30, thereby completing a circuit between the
common arm
16 and the secondary arm 30.
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[0034] Figure 1A shows a cross-sectional view of the switch body 12 of the
magnetically-
triggered proximity switch 10. The switch body 12 preferably has a generally
cylindrical
shape having a circular cross-section. However, the switch body 12 may have
any cross-
sectional shape, such as a polygon or an oval, for example. The switch body 12
may include
a first body half 12a and a second body half 12b. Because the second body half
12b may be
identical to the first body half 12a, only the first body half 12a is
illustrated. Each of the first
body half 12a and the second body half 12b may be formed from plastic and may
be
manufactured using conventional processes, such as injection-molding, for
example. The
plastic may be a high-temperature material that allows the switch body 12 to
be exposed to
environments that may damage conventional plastic materials. The first body
half 12a and
the second body half 12b may be joined into a single switch body 12, as
illustrated in Figures
1B, 1C and 3, using any of several methods known in the art, such as
ultrasonic welding or
by using an adhesive. Additionally, the switch body 12 may be hermetically
sealed to protect
the proximity switch from water or dirt particles. However, the switch body 12
may be made
of any suitable material and may be manufactured by any means known in the
art.
[0035] As illustrated in Figures 1A and 4, the semi-cylindrical first body
half 12a of the
switch body 12 may have a substantially planar mating surface 51 that is
adapted to engage a
corresponding mating surface (not shown) of the second body half 12b to form
the switch
body 12. The first body half 12a also includes an open first end 52 that
includes a semi-
cylindrical second magnet cavity 54, and the second magnet cavity 54 may
inwardly extend
along a longitudinal axis 56 of the body 12 that extends along the plane of
the mating surface
51. The second magnet cavity 54 may be sized to receive a detector magnet
assembly 58,
illustrated in Figure 2, that includes the disk-shaped second magnet 46 and a
magnet base 60
coupled to the second magnet 46, and the detector magnet assembly 58 may
slidably displace
within the second magnet cavity 54 along the longitudinal axis 56.
[0036] A semi-cylindrical first magnet cavity 62 may also be formed in the
first body half
12a to receive and secure the first magnet 14 within the body such that a
longitudinal axis of
the disk-shaped first magnet 14 is substantially aligned with the longitudinal
axis 56 of the
first body half 12a. A semi-cylindrical upper arm cavity 64 may extend along
the
longitudinal axis 56 between the second magnet cavity 54 and the first magnet
cavity 62, and
the upper arm cavity 64 may be sized to receive an elongated actuator arm 66
that extends
between the cross-arm 38 and the magnet base 60. A generally rectangular
contact cavity 68
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may be formed in the first body half 12a to receive the second end 20 of the
common arm 16,
the second end 26 of the primary arm 22, the second end 34 of the secondary
arm 30, the
cross arm 38, and a first end 116 of the actuator arm 66. A semi-cylindrical
lower arm cavity
70 may extend along the longitudinal axis 56 between the first magnet cavity
62 and the
contact cavity 68, and the lower arm cavity 70 may be sized to receive the
actuator arm 66.
A rectangular common slot 72 may extend from the contact cavity 68 to a second
end 74 of
the first body half 12a in a direction generally parallel to the longitudinal
axis 56 such that the
common slot 72 forms a common aperture 75 in a rear face 76 of the first body
half 12a. The
common slot 72 may be sized to receive the common arm 16 such that the first
end 18 of the
common arm 16 extends through the common aperture 75 formed in the rear face
76. A
rectangular primary slot 78 may extend from the contact cavity 68 to the
second end 74 of the
first body half 12a in a direction generally parallel to and offset from the
common slot 72
such that the primary slot 78 forms a primary aperture 80 in the rear face 76
of the first body
half 12a. The primary slot 78 may be sized to receive the primary arm 22 such
that the first
end 24 of the primary arm 22 extends through the primary aperture 80 in the
rear face 76. In
addition, a rectangular secondary slot 82 may extend from the contact cavity
68 to the second
end 74 of the first body half 12a in a direction generally parallel to and
offset from both the
common slot 72 and the primary slot 78 such that the secondary slot 82 forms a
secondary
aperture 84 in the rear face 76 of the first body half 12a. The secondary slot
82 may be sized
to receive the secondary arm 32 such that the first end 32 of the secondary
arm 32 extends
through the secondary aperture 84 in the rear face 76.
[0037] As discussed above and as illustrated in Figures 1A and 2, the
magnetically-
triggered proximity switch 10 also includes a detector magnet assembly 58
slidably disposed
within the second magnet cavity 54 of the first body half 12a and the second
body half 12b of
the switch body 12. The detector magnet assembly 58 may include a second
magnet 46, also
called a detector magnet, that may be cylindrical in shape. Preferably, the
second magnet 46
has the shape of a disk. The second magnet 46 may be a permanent magnet or any
other type
of suitable magnet. The detector magnet assembly 58 may also include a magnet
base 60 that
may have a planar bottom portion 86 and a circumferential side wall 88 that
extends away
from the bottom portion 86. The bottom portion 86 and side wall 88 may be
dimensioned to
receive the second magnet 46 such that a planar surface of the second magnet
46 is proximate
to the top of the side wall 88 and the outside radius of the second magnet 46
is slightly less
than the inner radius of the side wall 88. The magnet base 60 may be made from
a metal,
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such as stainless steel, and the second magnet 46 may be secured to the magnet
base 60 by a
magnetic force. Alternatively, the magnet base 60 may be made from a non-
magnetic
material, and the second magnet 46 may be mechanically or adhesively secured
to the magnet
base 60.
[0038] Referring again to Figures 1A and 2, the magnetically-triggered
proximity switch
further includes a first magnet 14, also called a bias magnet. The first
magnet 14 may be
cylindrical in shape, and may have the shape of a disk. The first magnet 14
may also have an
aperture 90 formed along the central longitudinal axis of the first magnet 14,
and the aperture
90 may be sized to receive the actuator arm 66. The first magnet 14 may be
received into the
first magnet cavity 62 of the switch body 12 such that the first magnet 14
cannot displace
when the first body half 12a and the second body half 12b are joined together
to form the
switch body 12. The first magnet 14 may be made from the same material as the
second
magnet 46, but the radius and the thickness of the first magnet 14 may each be
smaller than
the respective radius and thickness of the second magnet 46. The first magnet
14 may be
positioned within the first magnet cavity 62 such that the second magnet 46 is
attracted
towards the first magnet 14. That is, if a north pole of the second magnet 46
faces the second
end 74 of the switch body 12, a south pole of the first magnet 14 is disposed
facing the north
pole of the second magnet 46. Conversely, if a south pole of the second magnet
46 faces the
second end 74 of the switch body 12, a north pole of the first magnet 14 is
disposed facing
the south pole of the second magnet 46.
[0039] Referring to Figures 1A, 2, and 5A, the magnetically-triggered
proximity switch 10
also includes a common arm 16, which is a common component of the circuit
formed by the
first switch position and the circuit formed by the second switch position.
The common arm
16 may be a narrow strip of a conducting metal, such as copper or a copper
alloy, and the
common arm 16 may be formed from a stamping process. As discussed above, the
second
end 20 of the common arm 16 is disposed within the contact cavity 68 such that
common arm
16 extends through the common slot 72 formed in the switch body 12, and the
first end 18
protrudes through the common aperture 75 to a position outside of the switch
body 12. The
common arm 16 may be positioned within the common slot 72 such a longitudinal
axis of the
common arm 16 is parallel to the longitudinal axis 56 of the switch body 12,
while in a
transverse direction, the common arm 16 is perpendicular to the plane passing
through the
mating surface 51 of the first body half 12a. A rear surface 91 of the common
arm 16 may
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contact a first wall 92 of the common slot 72, the first wall 92 being
longitudinally aligned
with the common arm 16 and perpendicular to the plane of the mating surface
51, as shown in
Figure 4. A portion of the common arm 16 disposed within the common slot 72
may be
curved, and a top surface of the curved portion 94 may contact a second wall
96 forming the
common slot 72, the second wall 96 being offset from and parallel to the first
wall 92.
Because the transverse distance between the top surface of the curved portion
94 and the rear
surface 91 of the common arm 16 is greater than the distance between the first
wall 92 and
second wall 96 of the common slot 72, an interference fit is provided that
secures the
common arm 16 within the common slot 72. A bottom surface 98 of the common arm
16
may contact a third wall 100 forming the common slot 72 of the first body half
12a, the third
wall 100 being perpendicular to the first wall 92 and the second wall 96, and
a top surface
102 of the common arm 16 may contact a fourth wall (not shown) of the
corresponding
common slot 72 of the second body half 12b when the first body half 12a and
the second
body half 12b are assembled into the switch body 12. Because the third wall
100 of the
common slot 72 is closer to the plane formed by the mating surface 51 than a
bottom surface
98 of the contact cavity 68, a gap exists between the bottom surface 101 of
the common arm
16 and the bottom surface 101 of the contact cavity 68 of the first body half
12a. Similarly, a
gap exists between the top surface 102 of the common arm 16 and the top
surface (not
shown) of the contact cavity 68 of the second body half 12b. The common arm 16
may also
include a transverse slot 104 that extends across the width of the common arm
16 proximate
to the second end 20.
[0040] Referring to Figures 1 A and 2, the magnetically-triggered proximity
switch 10 also
includes a primary arm 22. The primary arm 22 may be made from the same
material as the
common arm 16, and the primary arm 22 may engage the primary slot 78 in the
same manner
that the common arm 16 engages the common slot 72. Accordingly, a curved
portion 106 of
the primary arm 22 provides an interference fit within the primary slot 78 to
retain the
primary arm 22 within the primary slot 78. In addition, the first end 24 of
the primary arm 22
extends from the primary aperture 80 formed in the rear face 76 of the switch
body 12 such
that when viewed normal to the mating surface 51, the first end 24 of the
primary arm 22 is
parallel to the first end 18 of the common arm 16. The second end 26 of the
primary arm 22
is coupled to a primary contact 28. The primary contact 28 may be made from a
conductive
metal, such as copper or a copper alloy, and the primary contact 28 may be
secured to the
primary arm 22 in any manner known in the art, such as soldering or mechanical
fastening.
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Alternatively, the primary contact 28 may be integrally formed with the second
end 26 of the
primary arm 22. The primary contact 28 may be disposed proximate to a first
cavity wall 108
that partially defines the contact cavity 68.
[0041] Referring again to Figures lA and 2, the magnetically-triggered
proximity switch
also includes a secondary arm 30. The secondary arm 30 may be made from the
same
material as the common arm 16, and the secondary arm 30 may engage the
secondary slot 82
in the same manner that the common arm 16 engages the common slot 72. However,
the
secondary arm 30 may be positioned within the secondary slot 82 in a "mirror
image"
relationship with the primary arm 22 in the primary slot 78. More
specifically, a top surface
of the curved portion 110 of the secondary arm 30 may face a top surface of
the curved
portion 106 of the primary arm 22. As configured, the first end 32 of the
secondary arm 30
extends from the secondary aperture 84 formed in the rear face 76 of the
switch body 12 such
that when viewed normal to the mating surface 51, the first end 32 of the
secondary arm 30 is
parallel to both the first end 24 of the primary arm 22 and the first end 18
of the common arm
16. The second end 34 of the secondary arm 30 is coupled to a secondary
contact 36.
Similar to the primary contact 28, the secondary contact 36 may be made from a
conductive
metal, such as copper or a copper alloy, and the secondary contact 36 may be
secured to the
secondary arm 30 in any manner known in the art, such as soldering or
mechanical fastening.
Alternatively, the secondary contact 36 may be integrally formed with the
second end 34 of
the secondary arm 30. The secondary contact 36 may be disposed proximate to a
second
cavity wall 112 of the contact cavity 68 that is offset from and parallel to
the first cavity wall
108.
[0042] Referring to Figures 1A, 2, and 5B, the magnetically-triggered
proximity switch 10
also includes a cross arm 38. The cross arm 38 may be formed from a narrow
strip of a
conducting metal, such as copper or a copper alloy, and the common arm 16 may
be formed
from a stamping process and subsequent bending process. A second end 42 of the
cross arm
38 may include a common contact 44. The common contact 44 may be made from a
conductive metal, such as copper or a copper alloy, and the common contact 44
may be
secured to the cross arm 38 in any manner known in the art, such as soldering
or mechanical
fastening. Alternatively, the common contact 44 may be integrally formed with
the second
end 42 of the cross arm 38. A first end 40 of the cross arm 38 may include an
end loop 114,
and a portion of the end loop 114 may be disposed within the transverse slot
104 of the
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common arm 16 such that the cross arm 38 may rotate about the second end 20 of
the
common arm 16 while maintaining contact with the common arm 16. The cross arm
38 may
be rotatable about the second end 20 of the common arm 16 between a first
switch position
and a second switch position. In the first switch position, shown in Figure
6A, the common
contact 44 of the cross arm 38 is in contact with the primary contact 28 of
the primary arm
22, thereby completing a circuit between the common arm 16 and the primary arm
22. In the
second switch position, shown in Figure 6B, the common contact 44 of the cross
arm 38 is in
contact with the secondary contact 36 of the secondary arm 30, thereby
completing a circuit
between the common arm 16 and the secondary arm 30.
[0043] Referring again to Figures 1A, 2, and 5B, the magnetically-triggered
proximity
switch 10 also includes an actuator arm 66. The actuator arm 66 may be an
elongated
cylinder having a first end 116 and a second end 118 opposite the first end
116. Instead of a
cylinder, the actuator arm 66 hay have any suitable cross-sectional shape or
combination of
shapes, such as that of a square, oval, or polygon. The actuator arm 66 may be
formed from a
plastic material or any other suitable material. The actuator arm 66 may be
slidably disposed
in the upper arm cavity 64 and the lower arm cavity 70 of the switch body 12,
and each of the
upper arm cavity 64 and the lower arm cavity 70 may have an inner diameter
that is slightly
greater than the outer diameter of the actuator arm 66. The actuator arm 66
may also extend
through the aperture 90 in the first magnet 14 when the first magnet 14 is
disposed within the
first magnet cavity 62. The first end 116 of the actuator arm 66 may include a
groove 120,
and the groove 120 may receive an edge portion 122 that defines the aperture
in the cross arm
38 to secure the actuator arm 66 to the cross arm 38, as shown in Figure 5B.
However, the
first end 116 may be coupled to the cross arm 38 by any means known in the
art, such as, for
example, mechanical fastening. The second end 118 of the actuator arm 66 may
be coupled
to the magnet base 60 of the detector magnet assembly 58 in a manner similar
to the coupling
of the first end 116 to the cross arm 38.
[0044] In operation, the first magnet 14 provides a magnetic force that
attracts the second
magnet 46. This attractive force displaces the detector magnet assembly 58
towards the first
magnet 14, thereby displacing the actuator arm 66 towards the second end 74 of
the switch
body 12. The displacement of the actuator arm 66 rotates the cross arm 38
about the second
end 20 of the common arm 16 such that the common contact 44 is in contact with
the primary
contact 28. In this first switch position, shown in Figure 6A, a circuit is
completed between
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the primary arm 22 and the common arm 16. Accordingly, the closed circuit that
results from
the first switch position can be detected by a processor that is operatively
connected to the
first end 18 of the common arm 16 and the first end 24 of the primary arm 22.
[0045] However, when a magnetic target 124, which may include a permanent
magnet or a
ferrous metal, is moved into a position within a predetermined range of the
proximity switch
10, the magnetic force between the target 124 and the second magnet 46 may be
greater than
the magnetic force between the second magnet 46 and the first magnet 14. The
greater force
displaces the detector magnet assembly 58 towards the target 124 and away from
the first
magnet 14, thereby displacing the actuator arm 66 that is rigidly coupled to
the magnet base
60 of the detector magnet assembly 58. As the actuator arm 66 is displaced,
the cross arm 38
is rotated about the second end 20 of the common arm 16 to move the common
contact 44 out
of contact with the primary contact 28 and into contact with the secondary
contact 36. In this
second switch position, shown in Figure 6B, a circuit is completed between the
secondary
arm 30 and the common arm 16. Accordingly, the closed circuit that results
from the second
switch position can be detected by a processor that is operatively connected
to the first end 18
of the common arm 16 and the first end 32 of the secondary arm 30. When the
target is no
longer within the predetermined range of the proximity switch 10, the magnetic
force
between the first magnet 14 and the second magnet 46 becomes greater than the
magnetic
force between the second magnet 46 and the target 124, and the proximity
switch 10 moves
into the first position in the manner described above.
[0046] One having ordinary skill in the art would recognize that the magnetic
force
between the target 124 and the second magnet 46 can depend on several factors,
such as the
relative size of the target 124 and the second magnet 46 and the distance
between the target
124 and the second magnet 46, and these variables can be adjusted to provide
for optimal
interaction between the proximity switch 10 and the target 124. In a similar
manner the
magnetic force between the second magnet 46 and the first magnet 14 can also
be adjusted.
[0047] One having ordinary skill in the art would also recognize that the
disclosed
embodiments of the magnetically-triggered proximity switch 10 allow for a
relatively small
switch body 12 having an integrated design, which further allows the
magnetically-triggered
proximity switch 10 to be used in applications with limited space
requirements, such as in
electrical junction boxes. It is also apparent to one having ordinary skill in
the art that the
disclosed embodiments of the magnetically-triggered proximity switch 10,
unlike typical
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proximity switches, do not need an external power source to function, thereby
simplifying
installation and extending the working life of the proximity switch 10.
[0048] Variations can be made to the disclosed embodiments of the proximity
switch 10
that are still within the scope of the appended claims. For example, instead
of the single
pole/single throw configuration described, a double pole/double throw
configuration is also
contemplated. In addition, LEDS may be included in the housing to visually
indicate
whether the proximity switch is in the first switch position or the second
switch position.
[0049] Figure 7A illustrates an alternative embodiment of a magnetically-
triggered
proximity switch 200 that includes a switch body 202 that extends along a body
longitudinal
axis 204, and a bias member 206 is non-movably secured within the switch body
202. The
magnetically-triggered proximity switch 200 also includes a first normally-
closed contact 208
having an engagement arm 210, a second normally-closed contact 212 having an
engagement
arm 214, a first normally-open contact 216 having an engagement arm 218, and a
second
normally-open contact 220 having an engagement arm 222. The magnetically-
triggered
proximity switch 200 further includes a contact magnet 224 disposed within the
switch body
202, the contact magnet 224 being movable relative to the bias member 206 such
that the
contact magnet 224 is movable between a first switch position 226 (illustrated
in Figure 9A)
and a second switch position 228 (illustrated in Figure 9B). In the first
switch position 226
illustrated in Figure 9A, the contact magnet 224 contacts a portion of the
engagement arm
210 of the first normally-closed contact 208 and a portion of the engagement
arm 214 of the
second normally-closed contact 212, thereby completing a circuit between the
first normally-
closed contact 208 and the second normally-closed contact 212. In the second
switch
position 228 illustrated in Figure 9B, the contact magnet 224 contacts a
portion of the
engagement arm 218 of the first normally-open contact 216 and a portion of the
engagement
arm 222 of the second normally-open contact 220, thereby completing a circuit
between the
first normally-open contact 216 and the second normally-open contact 220.
[0050] Referring to Figures 7A and 7B, the magnetically-triggered proximity
switch 200
includes the switch body 202 that extends along the body longitudinal axis 204
such that the
switch body 202 has a first end 232 and a second end 234 longitudinally
opposite the first end
232. The switch body 202 preferably has a generally cylindrical shape having a
circular
cross-section. However, the switch body 202 may have any cross-sectional
shape, such as a
polygon or an oval, for example. The switch body 202 may comprise a single,
unitary part or
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may comprise two or more component parts coupled to form the switch body 202.
For
example, the switch body 202 may include a first body half 230a and a second
body half
230b that combine to form the switch body 202, and the first body half 230a
and the second
body half 230b may be identical or substantially identical. Each of the first
body half 230a
and the second body half 230b may be formed from non-conductive material, such
as plastic,
ceramic, epoxy, or rubber, and may be manufactured using conventional
processes, such as
injection-molding, for example. The plastic may be a high-temperature material
that allows
the switch body 202 to be exposed to environments that may damage conventional
plastic
materials. The first body half 230a and the second body half 230b may be
joined to form the
switch body 202 using any of several methods known in the art, such as
ultrasonic welding or
by using an adhesive. However, the switch body 202 may be made of any suitable
material
and may be manufactured by any means known in the art.
[0051] As illustrated in Figures 7A, 9A, 9B, and 10, the first body half 230a
of the switch
body 202 may extend along the body longitudinal axis 204 from the first end
232 of the
switch body 202 to the second end 234 of the switch body. The first body half
230a may
have a substantially planar mating surface 236a that is adapted to engage a
corresponding
mating surface (not shown) of the second body half 230b to form the switch
body 202. The
first body half 230a may also include a first cavity 238a, and the first
cavity 238a may extend
along the body longitudinal axis 204 that extends along the plane of the
mating surface 236a.
The first cavity 238a may be disposed adjacent to the first end 232 of the
switch body 202,
and the first cavity 238a may be shaped and sized to receive a bias member 206
that will be
described in more detail below. For example, the first cavity 238a may be semi-
cylindrical
and may have a longitudinal axis that is coaxial with the body longitudinal
axis 204. More
specifically, the first cavity 238a may include a planar first wall 278a
disposed at a first
longitudinal portion of the first cavity 238a and a planar second wall 280a
disposed at a
second longitudinal portion of the first cavity 238a adjacent to the first end
232 of the switch
body 202. The first wall 278a and the second wall 280a may each be normal to
the body
longitudinal axis 204. A semi-cylindrical circumferential cavity surface 282a
may extend
between the first wall 278a and the second wall 280a, and a longitudinal axis
of the
circumferential cavity surface 282a may be coaxially-aligned with the body
longitudinal axis
204. So configured, when the first body half 230a and the second body half
230b are coupled
to form the switch body 202, the first cavity 238a of the first body half 230a
and the first
cavity 238b of second body half 230b combine to form a cylindrical first
cavity 238 that is
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symmetrical about the body longitudinal axis 204 and that has a longitudinal
axis aligned
with the body longitudinal axis 204.
[0052] Still referring to Figures 7A, 9A, 9B, and 10, the cylindrical first
cavity 238 formed
by the first cavity 238a of the first body half 230a and the first cavity 238b
of second body
half 230b is adapted to receive a disk-shaped bias member 206 (also called a
"bias disk")
such that the bias member 206 is non-movably secured (or substantially non-
movably
secured) within the cylindrical first cavity 238 of the switch body 202. More
specifically,
each of the longitudinal length (i.e., the longitudinal distance between the
first wall 278a,
278b and the second wall 280a, 280b) and the diameter of the cylindrical first
cavity 238 (i.e.,
the sum of the individual radii of the semi-cylindrical circumferential cavity
surface 282a,
282b) may be slightly larger (e.g., 3% to 10% larger) than each of the
longitudinal length and
diameter of the cylindrical bias member 206. The bias member 206 may have a
longitudinal
axis that is coaxially-aligned with the body longitudinal axis 204 when
disposed within the
first cavity 238. The bias member 206 may be made of a ferrous material (such
as steel), a
magnetic material, or any other material or combination of materials that
results in or causes
an attractive magnet force between the material and a magnet (i.e., the
contact magnet 224).
[0053] As illustrated in Figures 7A and 10, the first body half 230a of the
switch body 202
may include a second cavity 240a formed in the switch body 202. The second
cavity 240a
may be disposed between the first cavity 238a and the second end 234 of the
switch body 202
such that one end of the second cavity 240a may be adjacent to the second end
234 of the
switch body 202. The second cavity 240a may be shaped and sized to receive a
displaceable
contact magnet 224 that will be described in more detail below. For example,
the second
cavity 240a may be semi-cylindrical and may have a longitudinal axis that is
coaxial with the
body longitudinal axis 204. More specifically, the second cavity 240a may
include a planar
first wall 242a disposed at a first longitudinal end of the second cavity 240a
and a planar
second wall 244a disposed at a second longitudinal end of the second cavity
240a adjacent to
the second end 234 of the switch body 202. The first wall 242a and the second
wall 244a
may each be normal to the body longitudinal axis 204. A semi-cylindrical
circumferential
cavity surface 246a may extend between the first wall 242 and the second wall
244, and a
longitudinal axis of the circumferential cavity surface 246a may be coaxial
with the body
longitudinal axis 204. So configured, when the first body half 230a and the
second body half
230b are assembled to form the switch body 202, the circumferential cavity
surface 246a of
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the first body half 230a and the circumferential cavity surface 246b of the
second body half
230b cooperate to form a cylindrical surface of the second cavity 240 that is
symmetrically
disposed about (i.e., has a longitudinal axis co-axially aligned with) the
body longitudinal
axis 204. The first wall 242a and the second wall 244a may be longitudinally
separated by
any suitable distance to allow the contact magnet 224 to longitudinally
displace from a first
switch position 226 to a second switch position 228 (as illustrated Figures 9A
and 9B) in a
manner described in more detail below. The radius of the circumferential
cavity surface
246a, 246b (i.e., the diameter of the second cavity 240) may have any value
that allows the
contact magnet 224 to longitudinally displace from a first switch position 226
to a second
switch position 228 (as illustrated Figures 9A and 9B) in a manner described
in more detail
below.
[0054] Still referring to Figures 7A and 10, the first body half 230a may
further include a
first contact aperture 248 and a second contact aperture 250 that each extends
from an
exterior surface 252a of the first body half 230a to the circumferential
cavity surface 246a of
the first body half 230a. The first contact aperture 248 and the second
contact aperture 250
may intersect the circumferential cavity surface 246a at or adjacent to the
second wall 244a
of the second cavity 240a. For example, a portion of first contact aperture
248 and a portion
of the second contact aperture 250 may contact (or may be immediately adjacent
to) the edge
formed by the intersection of the circumferential cavity surface 246a and the
second wall
244a. The first contact aperture 248 and the second contact aperture 250 may
each extend
along a longitudinal axis, and each longitudinal axis may be parallel and may
extend along a
first reference plane 254 that is orthogonal to the body longitudinal axis
204. The first
contact aperture 248 and the second contact aperture 250 may be symmetrically
disposed
about the body longitudinal axis 204 (i.e., equidistant from the body
longitudinal axis 204)
when viewed normal to the planar mating surface 236a. The first contact
aperture 248 and
the second contact aperture 250 may have any suitable size and shape to
receive the
engagement arm 218 of the first normally-open contact 216 and the engagement
arm 222 of
the second normally-open contact 220, respectively. For example, if the
engagement arms
218, 222 each have a circular cross-sectional shape, the first contact
aperture 248 and the
second contact aperture 250 may each have a circular cross-sectional shape
with a diameter
slightly larger than the diameter of the engagement arms 218, 222.
Alternatively, the
diameter of the first contact aperture 248 and the second contact aperture 250
may be
substantially equal to (or slightly less than) the diameter of the engagement
arms 218, 222 to
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allow for an interference fit to secure the engagement arms 218, 222 within
the first contact
aperture 248 and the second contact aperture 250. The first contact aperture
248 and the
second contact aperture 250 may have one or more internal tabs, ridges, fins,
or other features
that may act to engage and retain the engagement arm 218 of the first normally-
open contact
216 and the engagement arm 222 of the second normally-open contact 220.
[0055] Still referring to Figures 7A and 10, the second body half 230b may
include a first
contact aperture 256 and a second contact aperture 258 that each extends from
an exterior
surface 252b of the second body half 230b to the circumferential cavity
surface 246b of the
second body half 230b. The first contact aperture 256 and the second contact
aperture 258
may intersect the circumferential cavity surface 246b at or adjacent to the
first wall 242b of
the second cavity 240b of the of the second body half 230b. For example, a
portion of first
contact aperture 256 and a portion of the second contact aperture 258 may
contact (or may be
immediately adjacent to) the edge formed by the intersection of the
circumferential cavity
surface 246b and the first wall 242b. The first contact aperture 256 and the
second contact
aperture 258 may each extend along a longitudinal axis, and each longitudinal
axis may be
parallel and may extend along a second reference plane 260 that is orthogonal
to the body
longitudinal axis 204 and longitudinally offset from the first reference plane
254. The first
contact aperture 256 and the second contact aperture 258 may be symmetrically
disposed
about the body longitudinal axis 204 (i.e., equidistant from the body
longitudinal axis 204)
when viewed normal to the planar mating surface 236b of the second body half
230b. In
addition, the longitudinal axis of the first contact aperture 248 of the first
body half 230a may
be longitudinally aligned (i.e., aligned with a reference axis that is
parallel to the body
longitudinal axis 204) with the longitudinal axis of the first contact
aperture 256 of the
second body half 230b when viewed normal to the planar mating surface 236a of
the first
body half 230a. Similarly, the longitudinal axis of the second contact
aperture 250 of the first
body half 230a may be longitudinally aligned (i.e., aligned with a reference
axis that is
parallel to the body longitudinal axis 204) with the longitudinal axis of the
second contact
aperture 258 of the second body half 230b when viewed normal to the planar
mating surface
236a of the first body half 230a. The first contact aperture 256 and the
second contact
aperture 258 may have any suitable size and shape to receive the engagement
arm 210 of the
first normally-closed contact 208 and the engagement arm 214 of the second
normally-closed
contact 212, respectively. For example, if the engagement arms 210, 214 each
have a circular
cross-sectional shape, the first contact aperture 256 and the second contact
aperture 258 may
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each have a circular cross-sectional shape with a diameter slightly larger
than the diameter of
the engagement arms 210, 214. Alternatively, the diameter of the first contact
aperture 256
and the second contact aperture 258 may be substantially equal to (or slightly
smaller than)
the diameter of the engagement arms 210, 214 to allow for an interference fit
to secure the
engagement arms 210, 214 within the first contact aperture 256 and the second
contact
aperture 258. The first contact aperture 256 and the second contact aperture
258 may have
one or more internal tabs, ridges, fins, or other features that may act to
engage and retain the
engagement arm 210 of the first normally-closed contact 208 and the engagement
arm 214 of
the second normally-closed contact 212.
[0056] As illustrated in Figures 7A and 10, the first body half 230a may also
include a first
auxiliary contact aperture 264 and a second auxiliary contact aperture 266
that are each
coaxially aligned with the first contact aperture 256 and the second contact
aperture 258,
respectively, of the second body half 230b. Similarly, the second body half
230b may also
include a first auxiliary contact aperture 268 and a second auxiliary contact
aperture 270 that
are each coaxially aligned with the first contact aperture 248 and the second
contact aperture
250, respectively, of the first body half 230a.
[0057] Referring to Figure 7A, the first body half 230a may include one or
more
longitudinal grooves 262a formed in the exterior surface 252a. For example,
the first body
half 230a may include two grooves 262a that extend along the exterior surface
252a such that
the each of the grooves 262a is parallel to the body longitudinal axis 204. A
first of the two
grooves 262a may intersect the first contact aperture 248 and the first
auxiliary contact
aperture 264 such that each of the first contact aperture 248 and the first
auxiliary contact
aperture 264 intersects the exterior surface 252a within the first groove
262a. A second of
the two grooves 262a may intersect the second contact aperture 250 and the
second auxiliary
contact aperture 266 such that each of the second contact aperture 250 and the
second
auxiliary contact aperture 266 intersects the exterior surface 252a within the
second groove
262a. Each of the first and second grooves 262a may extend from the first end
232 of the
switch body 202 to a point adjacent to the second end 234 of the switch body
202. Referring
to Figures 7A, the second body half 230b may include one or more longitudinal
grooves 262b
formed in the exterior surface 252b. For example, the second body half 230b
may include
two grooves 262b that extend along the exterior surface 252b such that the
each of the
grooves 262b is parallel to the body longitudinal axis 204. A first of the two
grooves 262b
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may intersect the first contact aperture 256 and the first auxiliary contact
aperture 268 such
that each of the first contact aperture 256 and the first auxiliary contact
aperture 268
intersects the exterior surface 252b within the first groove 262b. A second of
the two
grooves 262b may intersect the second contact aperture 258 and the second
auxiliary contact
aperture 270 such that each of the second contact aperture 258 and the second
auxiliary
contact aperture 270 intersects the exterior surface 252b within the second
groove 262b.
Each of the first and second grooves 262b may extend from the first end 232 of
the switch
body 202 to a point adjacent to the second end 234 of the switch body 202.
Each of the
grooves 262a, 262b may have an identical cross-sectional shape that is adapted
to receive a
portion of one of the first normally-closed contact 208, the second normally-
closed contact
212, the first normally-open contact 216, and the second normally-open contact
220 in a
manner that will be described in more detail below.
[0058] As illustrated in Figures 7A, 7B, 8A, 8B, 9A, and 9B, the magnetically-
triggered
proximity switch 200 may include the first normally-closed contact 208 and the
second
normally-closed contact 212. The first normally-closed contact 208 may include
the
engagement arm 210 that is received into the first contact aperture 256 of the
second body
half 230b. The engagement arm 210 may have any suitable shape, such as, for
example, an
elongated, cylindrical shape having a longitudinal axis that is coaxially
aligned with the
longitudinal axis of the first contact aperture 256. The first normally-closed
contact 208 may
also include an elongated extension arm 272 that extends from a distal end 274
of the
engagement arm 210. The extension arm 272 may have any suitable shape, such
as, for
example, an elongated, cylindrical shape having a longitudinal axis that is
disposed
orthogonal to the longitudinal axis of the engagement arm 210 such that the
first normally-
closed contact 208 has an L-shape. With the engagement arm 210 received into
the first
contact aperture 256 of the second body half 230b, the extension arm 272 is
longitudinally
received into a corresponding groove 262b formed on the exterior surface 252b
of the second
body half 230b such that a distal end 276 of the extension arm 272 extends
beyond the first
end 232 of switch body 202. So positioned, the engagement arm 210 that is
received into the
first contact aperture 256 of the second body half 230b may also be at least
partially received
into the first auxiliary contact aperture 264 of the first body half 230a to
further secure the
engagement arm 210 within the switch body 202.
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[0059] The second normally-closed contact 212 may include the engagement arm
214 that
is received into the second contact aperture 258 of the second body half 230b
and the second
auxiliary contact aperture 266 of the first body half 230a in the same manner
that the
engagement arm 210 of the first normally-closed contact 208 is received into
the first contact
aperture 256 of the second body half 230b and the first auxiliary contact
aperture 264 of the
first body half 230a, respectively. An elongated extension arm 286 may extend
from a distal
end 288 of the engagement arm 214, and the extension arm 286 may be
longitudinally
received into a corresponding groove 262b formed on the exterior surface 252b
of the second
body half 230b such that a distal end 290 of the extension arm 286 extends
beyond the first
end 232 of switch body 202.
[0060] Referring again to Figures 7A, 7B, 8A, 8B, 9A, and 9B, the magnetically-
triggered
proximity switch 200 may include the first normally-open contact 216 and the
second
normally-open contact 220. The first normally-open contact 216 may include the
engagement arm 218 that is received into the first contact aperture 248 of the
first body half
230a and the first auxiliary contact aperture 268 of the second body half 230b
in the same
manner that the engagement arm 210 of the first normally-closed contact 208 is
received into
the first contact aperture 256 of the second body half 230b and the first
auxiliary contact
aperture 264 of the first body half 230a, respectively. An elongated extension
arm 292 may
extend from a distal end 294 of the engagement arm 218, and the extension arm
292 may be
longitudinally received into a corresponding groove 262a formed on the
exterior surface 252a
of the first body half 230a such that a distal end 296 of the extension arm
292 extends beyond
the first end 232 of switch body 202.
[0061] The second normally-open contact 220 may include the engagement arm 222
that is
received into the second contact aperture 250 of the first body half 230a and
the second
auxiliary contact aperture 270 of the second body half 230b in the same manner
that the
engagement arm 210 of the first normally-closed contact 208 is received into
the first contact
aperture 256 of the second body half 230b and the first auxiliary contact
aperture 264 of the
first body half 230a, respectively. An elongated extension arm 298 may extend
from a distal
end 300 of the engagement arm 222, and the extension arm 298 may be
longitudinally
received into a corresponding groove 262a formed on the exterior surface 252a
of the first
body half 230a such that a distal end 302 of the extension arm 298 extends
beyond the first
end 232 of switch body 202. Configured as described, the extension arms 272,
286, 292, 298
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may be parallel and the distal ends 284, 290, 296, 302 of the extension arms
272, 286, 292,
298 may each be longitudinally equidistant from the first end 232 of the
switch body 202.
The first and second normally-closed contacts 208, 212 and the first and
second normally-
open contact 216, 220 may each be made from any suitable non-magnetic
conducting
material or combination of materials, such as copper or silver, for example.
The first and
second first normally-closed contacts 208, 212 and the first and second
normally-open
contact 216, 220 may also be fully or partially coated (e.g., coated only at
portions intended
to engage the contact magnet 224) by any suitable plating, such as gold
plating.
[0062] Once again referring to Figures 7A, 7B, 8A, 8B, 9A, and 9B, the
magnetically-
triggered proximity switch 200 may include a body sleeve 304 that surrounds
the switch body
202 from the first end 232 and a second end 234. The body sleeve 304 may
correspond in
cross-sectional shape to the cross-sectional shape of the switch body 202. For
example, if the
switch body 202 (that may be comprised of the first body half 230a and the
second body half
230b) has a cylindrical shape having a circular cross-section, the body sleeve
304 may have a
cylindrical inner surface 306 and an outer surface 308. The outer surface 308
may have any
suitable shape, such as a cylindrical shape, and may include one or more
mounting features
(not shown). The inner surface 306 may have a diameter that is slightly larger
than the outer
diameter of the cylindrical exterior surface (i.e., the exterior surfaces
252a, 252b) of the
switch body 202, and a longitudinal axis of the inner surface 306 and the
outer surface 308
may be coaxially aligned with the body longitudinal axis 204. A slight gap may
exist
between the inner surface 306 of the body sleeve 304 and the cylindrical
exterior surface 252
of the switch body 202 to accommodate the extension arms 272, 286, 292, 298
disposed in
the grooves 262a, 262b formed in the exterior surfaces 252a, 252b of the
switch body 202,
and contact between the inner surface 306 body sleeve 304 the extension arms
272, 286, 292,
298 may maintain the associated engagement arms 210, 214, 218, 222 in a
desired position
relative to the switch body 202. The gap between the inner surface 306 of the
body sleeve
304 and the cylindrical exterior surface 252 of the switch body 202 may be
filled with an
epoxy and/or any other suitably sealing material to prevent water or dirt from
entering the
gap. The body sleeve 304 may include an end wall 309 disposed at a
longitudinal end of the
body sleeve 304 adjacent to the second end 234 of the switch body 202, and the
end wall 309
may close off the longitudinal end of the body sleeve 304. The end wall 309
may be planar
and may extend normal to the body longitudinal axis 204. Instead of having an
end wall 309,
the longitudinal end of the body sleeve 304 adjacent to the second end 234 of
the switch body
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202 may be open. The body sleeve 304 may be formed from any suitable non-
conductive
and non-magnetic material, such as the same non-conductive plastic material
used to form the
switch body 202 (e.g., plastic, ceramic, epoxy, or rubber).
[0063] As illustrated in Figures 7A, 9A, and 9B, the magnetically-triggered
proximity
switch 200 also includes the contact magnet 224 disposed within the switch
body 202. More
specifically, the contact magnet 224 may be disposed within the second cavity
240 of the
switch body 202 that may be a cylindrical cavity formed by the semi-
cylindrical second
cavity 240a of the first body half 230a and the semi-cylindrical second cavity
240b of the
second body half 230b. The contact magnet 224 may be spherical in shape and
may have a
diameter that is slightly smaller than (e.g., 3% to 15% smaller than) the
diameter of the
cylindrical second cavity 240. The contact magnet 224 may be made from or
coated with a
conductive material. For example, the contact magnet 224 may be a spherical
neodymium
magnet that is gold plated. However, the contact magnet 224 may have any shape
or size that
allows the contact magnet 224 to longitudinally displace from the first switch
position 226
(illustrated in Figure 9A) to the second switch position 228 (illustrated in
Figure 9B).
[0064] Assembled as described, with the bias member 206 in the first cavity
238 of the
switch body 202 and the contact magnet 224 disposed within the second cavity
240 of the
switch body 202, an attractive magnetic force (i.e., the first magnetic force)
acts between the
bias member 206 and the contact magnet 224 to maintain the contact magnet 224
in the first
switch position 226 (illustrated in Figure 9A). In this first switch position
226, the
conductive contact magnet 224 is in contact with a portion of the engagement
arm 210 of the
first normally-closed contact 208 and a portion of the engagement arm 214 of
the second
normally-closed contact 212, thereby completing a circuit between the first
normally-closed
contact 208 and the second normally-closed contact 212. Also in this first
switch position
226, the conductive contact magnet 224 is not in contact with any portion of
the engagement
arm 218 of the first normally-open contact 216 or any portion of the portion
of the
engagement arm 222 of the second normally-open contact 220, thereby resulting
in an open
circuit between the first normally-open contact 216 and the second normally-
open contact
220. Accordingly, the closed circuit that results from the first switch
position 226 can be
detected by a processor, controller, or other detector that is operatively
connected to a portion
(such as the distal end 284) of the extension arm 272 of the first normally-
closed contact 208
and to a portion (such as the distal end 290) of the extension arm 286 of the
second normally-
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WO 2013/119723 PCT/US2013/025011
closed contact 212. Similarly, the open circuit that results from the first
switch position 226
can be detected by a processor, controller, or other detector that is
operatively connected to a
portion (such as the distal end 296) of the extension arm 292 of the first
normally-open
contact 216 and to a portion (such as the distal end 302) of the extension arm
298 of the
second normally-open contact 220.
[0065] However, when a magnetic target 310, which may be formed from or
include a
permanent magnet or a ferrous metal, is moved into a position within a
predetermined range
of the proximity switch 200, as illustrated in Figure 9B, the magnetic force
between the target
310 and the contact magnet 224 (i.e., the second magnetic force) may be
greater than the first
magnet force (i.e., the attractive magnetic force between the contact magnet
224 and the bias
member 206). Within the predetermined range, the more powerful second magnetic
force
acts to longitudinally displace the contact magnet 224 from the first switch
position 226
illustrated in Figure 9A to the second switch position 228 illustrated in
Figure 9B. In this
second switch position 228, the conductive contact magnet 224 is in contact
with a portion of
the engagement arm 218 of the first normally-open contact 216 and a portion of
the
engagement arm 222 of the second normally-open contact 220, thereby completing
a circuit
between the first normally-open contact 216 and the second normally-open
contact 220.
Accordingly, the closed circuit that results from the second switch position
228 can be
detected by a processor, controller, or other detector that is operatively
connected to a portion
(such as the distal end 296) of the extension arm 292 of the first normally-
open contact 216
and to a portion (such as the distal end 302) of the extension arm 298 of the
second normally-
open contact 220. Also in this second switch position 228, the conductive
contact magnet
224 is not in contact with any portion of the engagement arm 210 of the first
normally-closed
contact 208 or any portion of the engagement arm 214 of the second normally-
closed contact
212, thereby resulting in an open circuit between the first normally-closed
contact 208 and
the second normally-closed contact 212. Accordingly, the open circuit that
results from the
second switch position 228 can be detected by a processor, controller, or
other detector that is
operatively connected to connected to a portion (such as the distal end 284)
of the extension
arm 272 of the first normally-closed contact 208 and to a portion (such as the
distal end 290)
of the extension arm 286 of the second normally-closed contact 212.
[0066] When the target 310 is no longer within the predetermined range of the
proximity
switch 200, the magnetic force between the bias member 206 and the contact
magnet 224
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(i.e., the first magnetic force) becomes greater than the magnetic force
between the contact
magnet 224 and the target 310 (i.e., the second magnetic force), and the first
magnetic force
longitudinally displaces the contact magnet 224 from the second switch
position 228 to the
first switch position 226 in the manner described above.
[0067] As previously explained, the circumferential cavity surface 246a of the
first body
half 230a and the circumferential cavity surface 246b of the second body half
230b cooperate
to form or at least partially define the cylindrical surface of the second
cavity 240. The
cylindrical surface of the second cavity 240 may have any suitable diameter
that allows the
contact magnet 224 to longitudinally displace from the first switch position
226 to the second
switch position 228 and vice versa. More specifically, the cylindrical surface
of the second
cavity 240 may be adapted to limit or prevent movement of the contact magnet
224 in a
direction normal to the body longitudinal axis 204 when the contact magnet 224
is in the first
switch position 226, the second switch position 228, or longitudinally
displacing from the
second switch position 228 to the first switch position 226 (and vice versa).
Preferably, the
diameter of the cylindrical surface of the second cavity 240 may be slightly
larger (e.g., 5%
to 15% larger) than the diameter of the spherical contact magnet 224.
[0068] One having ordinary skill in the art would recognize that the magnetic
force
between the target 310 and the contact magnet 224 may depend on several
factors, such as
the relative size of the target 310 and the contact magnet 224, the distance
between the target
310 and the contact magnet 224, and these variables can be adjusted to provide
a desired
predetermined range for a particular application. In a similar manner the
magnetic force
between the contact magnet 224 and the bias member 206 can also be adjusted.
[0069] One having ordinary skill in the art would also recognize that the
disclosed
embodiments of the magnetically-triggered proximity switch 200 allow for a
relatively small
switch 202 having a simple actuating mechanism that includes a single moving
part (i.e. , the
contact magnet 224) that acts as both an actuator and a contact. This
simplified design
minimizes the number of assembly components and reduces the number of assembly
operations, thereby reducing manufacturing costs and assembly time. The
simplified design
also permits an overall size reduction (limited only by the contact magnet's
224 diameter)
that allows the magnetically-triggered proximity switch 200 to be used in
applications with
limited space requirements, such as in electrical junction boxes. Because the
magnetically-
triggered proximity switch 200 is intended for the switching of PLC level
loads (such as 5V,
CA 02862726 2014-07-24
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for example) or lower, the contact sizes can be correspondingly small, thereby
allowing for a
further size reduction of the proximity switch 200. It is also apparent to one
having ordinary
skill in the art that an external power source is not necessary, thereby
simplifying installation
and extending the working life of the proximity switch 200.
[0070] While various embodiments have been described above, this disclosure is
not
intended to be limited thereto. Variations can be made to the disclosed
embodiments that are
still within the scope of the appended claims. For example, two or more
switching circuits
(each including, for example, a bias member 206, a contact magnet 224, and a
plurality of
contacts 208, 212, 216, 220) may be included in a single switch body 202 of
the proximity
switch 200, and each switching circuit may operate independently to allow a
contact magnet
224 of each circuit to move from a first switch position 226 to a second
switch position 228
in the manner previously described. The two or more switching circuits may be
positioned
in a linear orientation within the switch body 202 to measure linear travel.
Alternatively, the
two or more switching circuits may be disposed in a grid pattern within the
switch body 202
to allow for X-Y target positioning (e.g., positioning in a direction along
the body
longitudinal axis 204 and normal to the body longitudinal axis 204). In
additional
embodiments, the proximity switch 200 may be hermetically sealed to protect
the proximity
switch 200 from water or dirt particles or to allow the proximity switch 200
to be used in
hazardous locations. In addition, LEDS may be included in or on a portion of
the switch
body 202 or the body sleeve 204 to visually indicate whether the proximity
switch 200 is in
the first switch position 226 or the second switch position 228.
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