Note: Descriptions are shown in the official language in which they were submitted.
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Description
Switch Actuator Apparatus
Technical Field
This invention relates to an apparatus for
actuating a switch and more particularly to an
apparatus for controllably actuating a switch in
response to a seat assembly being moved to a
preselected elevational position relative to a seat
support frame of a vehicle.
Background Art
Apparatuses for actua'ting a switch in response
to elevational movement of at least a portion of a seat
assembly of a vehicle such as a lift truck are well
known in the art. Examples of such systems are shown
in U.S. Patent 2,708,005 to Gazzo issued May 10, 1955,
U.S. Patent 3,437,993 to Recio et al issued April 8,
1969, U.S. Patent 3,500,946 to Boyajian issued March
17, 1970; U.S. Patent 3,703,618 to Lewis issued
November 21, 1972; U.S, Patent 3,70~,352 to Fontaine
issued November 28, 1972, U.S. Patent 4,075,443 to
Fatur issued February 21, 1978, and German Patent
1,048,784 issued January 15, 1959.
Such apparatuses are often disposed between
the seat assembly and the switch for actuating the
switch in response to movement of the seat assernbly
toward the switch due to the weight of a vehicle
operator being seated thereon and for deactivating the
switch in response to movement of the seat assembly
away from the switch due to the weight of the vehicle
operator being removed therefrom.
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Typically such switches are operatively
connected to a vehicle system for establishing an on or
off condition of the system, as determined by an
occupied or unoccupied vehicle seat asserably, and
-5 permitting or preventing travel of the vehicle.
It has been found that during operation of the
vehicle over rought terrain prior switch actuating
apparatuses are often too sensitive to seat assembly
movement which causes cyclical and unclesirable
aetuation of the switch between the actuated and
unactuated positions which results in turning on and
off the vehicle system.
Such prior actuating apparatuses do not have
provisions for limiting the maximum amount of actuating
force applied to the switch. Since the weight of the
operator under dynamic conditions applies a variable
force to the seat assembly of a substantial magnitude
and the force applied to the switch is proportional to
the force on the seat, a condition rnay be developed
when the switch actuating force is beyond the
structural limits of the switch. This exeessive force
can eause premature failure of the switch which will
result in down time of the vehicle.
Often the switch is mounted on the seat
assembly for elevational movement with or in response
to elevational movement of the seat assembly. When
this movement is appreciable, substantial flexing of
electrical wires connecting the switch to the vehiele
system is observed. This flexing frequently causes
breakage of the wires which causes vehicle downtime.
Also, since the switch is mounted on the seat assembly
removal of the seat assembly from the vehicle or
movement of the seat assembly for operator comfort
adjustrnent in a horizontal clirection relative to a seat
support surface causes substantial flexing, stretching
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and bending of the wires. Also, removal of the seat
assembly frequently re~uires disconnection or xemoval
o~ the switch. In addltion, such systems do not
include a provision whereln ease of adjusbment o~ the
actuating apparatus can be made for establishing the
minimum weight on the seat at whlch switch actuation is
achleved,
The present invention is directed to
overcoming one or more of the pxoblems as set forth
10 above.
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D'i'sclosur'e of the Inv~ention
In one aspect of the present invention an
apparatus for controllably actuating a switch mounted
on a support frame is provided. The actuating
apparatus is operatively associated with a vehicle seat
and the switch for applying an actuating force to the
switch of a smaller magnitude than a $orce applied to '
the seat and limits the force applied to the switch to
a preselected maximum value which is less than the
force applied to the seat.
B~rief Descr,lption of the Drawings
Fig. 1 is a diagrammatiç front elevational
view of the seat assembl~ and one embodiment of an actuatin~
apparatus of the present invention with portions thereof
broken out and ln section;
Fig. 2 is a diagxa~,matic side elevational view
of an alternate embodiment o.~ the seat assembly and
actuatin~ appa,ratus of the present invention with
portions thereof broken out and in section; and
Fig. 3 is a dia~rammatic top elevational view
o~ the ac~uating apparatus taken along the line III-III
of FIg. 2~
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seSt Mode for Carrying Out the Invention
Referring to -the preferred embodiment of Fig.
1, a seat assembly 10, for a vehicle such as a lift
truck (not shown) is pivo-tally attached to a support
frarne 12, which may be the frame of the vehicle. The
seat assembly 10 includes a seat 14 having a base 16
and a connecting frarne 18. The seat 14 is mounted on
the connecting frame 18 and the connecting frame is
pivotly secured to the support frame 12. More
specifically, the base 16 of the seat 14 is mounted on
and rig;dly secured to a guide rail assembly 20 in any
suitable manner and the guide rail assembly is moun-ted
on the connecting frame 18 and securecl thereto by
threaded fasteners 22. The guide rail assembly 20 is
of a construction well ~nown in the art and permits
selected guided movement of the seat in a horizontal
plane parallel to the connecting frame 18 so as to
provide comfortable seating for a vehicle operator.
The connecting frame 18 has a first and second
20 end portion 24,26. The first end portion 2~ is pivotly
secured to the support frame by a hinge assembly 28
having a pivot pin 30. The connecting frame 18 of the
seat assembly 10 is elevationally movable relative to
the support frarne 12 as it pivots about pin 30.
A resilient member 32, of preferably rubber
material, but may include coil or leaf springs, is
disposed between a lower surface 34 of the connecting
frame 18 and an upper surface 36 of the support frame
12 at a location spaced from the pivot pin 30. More
specifically, the resilient member is affixed to the
upper surface 36 of the support frame, in any suitable
manner, so as to be in contacting engagement with the
lower surface 34 of the connecting frame 18 at a
location between the first and second end portions
35 24,26. It is to be noted that the resilient member 32
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maintains a ~ap or space 38 between the upper and lower
surfaees 36,34 when the seat is unoccupied. The
placement of a load on the seat 14 will eause
compression of the resilient member 32 resulting in a
reduetion of the spaee or gap 38.
An actuator apparatus 40 is operatively
associated with the seat assembly 10 and a switch 42.
The actuator apparatus 40 includes an aetuator spring
44 which has a first and seeond end portion 46,48. The
actuator spring 44 is preferably a leaf spring 50,
however, other types of springs sueh as eoil or torsion
would be suitable substitutes. The seeond end portion
48 of the leaf spring 50 is seeurely attaehed to the
eonneeting frame 18, at a location on the conneeting
frame spaced from the pivot pin 30, by a threaded
fastener 52 and the first end portion 46 of the leaf
spring 50 is free from eonneetion with the eonneeting
frame 18. The seeond end pcrtion 48 of the leaf spring
50 is preferably eonneeted to the seeond encl portion 26
of the eonneeting frame 18 and the first end portion 46
extends to terminate in an areuate shape at a loeation
spaeed further away from the pivot pin 30 than the
conneetion of the springs seeond end portion 48 and
beyond the eonneeting frame~'s seeond end portion 26.
An adjustment serew 54 is threadabIy connected
to the second end portion 26 of the conneeting frame 18
and threadably extensible relative to the eonneeting
frame 18. The serew!54 is contaetable with the spring
50 for selectively determining the elevational position
of the first end portion 46 of the spring 50 relative
to the eonnecting frame and the switeh 42.
The switch 42 is connectecl to the support
frame 12 by a bracket 56. Preferably the bracket is
"L" shaped and constructed of a resilient material sueh
as spring steel. One end portion 58 of the braeket 56
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is connected to the support frame 12 in any suitable
manner and the other end portion 60 iS connected to the
switch 42 such as by fasteners 62~ Specifically, the
resilient bracket 56, suspends and positions the switch
42 directly beneath the first end portion 46 of the
actuator spring 44.
The switch 42 has a plunger 64 which is
movable in response to an external force applied
thereto for placing the switch in one of an open and
closed position. The switch 42 is also movable from
one of said open and closed positions to the other of
the open and closed positions in response to the force
being removed therefrom. Such switch construction is
well known in the art and will not be discussed in
further detail. A plurality of electrical wire leads
66 are connected at one end to the switch 42. The
other end of the leads 66 are connected to an
electrical vehicle system (not shown)~ The electrical
vehicle system is operative in response to the switch
being in one of the open and closed positions and
inoperative in response to the switch being in the
other of the open and closed positions.
Referring to the alternate embodiment of Fig.
2, a seat assembly 110, is affixed to a support frame
112, which may be the frame of a vehicle. The seat
assembly 110 includes a seat 114 having a base 116, a
cushion 117 and cushion suspension springs 118. Such a
construction is well known in the art and will not be
discussed in any greater detail. The base 116 of seat
114 is mounted on and rigidly secured to a guide rail
assembly 120 and the guide rail assembly 120 is mounted
on and rigidly secured to the support frame 112. The
guide rail assembly 120 is of a construction well known
in the art and permits selected guided movement of the
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seat 114 in a horizontal plane parallel to the support
frame 112 so as to provide adjustment for comfortable
seating by a vehicle operator.
An actuator apparatus 122 is operatively
associated with the seat assembly 110 and a switch
124. The actuator apparatus includes an actuator
spring 126 which has a first and second end portion -
128,130 and a middle portion 132. Preferably, the
actuator spring 126 is an elongated arcuate shaped leaf
10 spring 134 having an upper surface 136. The first end
portion 128 of the actuator spring 126 is pivotly
connected to a pivot pin 133 of a support bracket 140.
The support braclcet is securely fastened to the support
frame 112 by fasteners 141. More specifically, the
15 first end portion 128 of the leaf spring 134 has an
aperature 142 defined therein which is open in a
transverse direction relative to the elongated
extension of the leaf spring. The pin 138 is disposed
in the aperature 142 and permits pivotal movement of
20 the first, second and middle portions 128,130,132 of
the actuator spring 126 about said pin.
Referring to Figs. 2 and 3, the switch 124 is
pivotly attached to the bracket 140 by fastener 148 so
that a plunger 150 faces the first end portion 128 of
25 the leaf spring 134. The plunger 150 is movable in
response to an external force applied thereto for
placing the switch 124 in one of an open and closed
position and movable from one of the open and closed
positions in response to the force being removed
therefrom to the other of the open and closed
positions. Such switch construction is well known in
the art and will not be discussed in further detail.
An adjustrnent screw 152 is screw threadably secured to
a vertical end portion 154 of the bracket 140 and
passes through the end portion 154 to engage the switch
124.
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Preferably the screw 154 engages a flange 156
which is rigidly secured to the switch 124 by fasteners
158. A tension spring 159 connected between the
vertical end portion 154 and the flange 156 biases the
switch 124 to pivot about the fastener 148 and
maintains the flange 156 in contact with the adjustment
screw 152. Therefore adjustrnent of the screw 152 will
cause the switch to move toward or away from the first
end portion 128 of the actuator spring 126. The
brac~et 140 further includes a stop 1600 The stop 160
is elevationally positioned between the actuator spring
126 and the support frame 112, and between the first
and second end portions 128,130 of the actuator spring
126. The stop is a substantially rectangular tab 162
which extends from the bracket 140 a preselected
distance at a location adjacent the pivot pin 138
transverse to the elongate extension of the leaf spring
134 to pass beneath the leaf spring. The rectangular
tab 162 is best located between the pivot pin 138 and
the middle portion 132 of the leaf spring 134 and at an
elevational location within a horizontal projection of
the diameter of the pivot pin 138.
The second end portion 130 of the actuator : .
spring 126 terminates in a curvalinear portion 164.
The curvalinear portion is in slideable tangential
contact with an upper surface 166 of the support frame
112.
The middle portion of the actuator spring 126
and specifically the upper surface 136 thereof is in
corltinuous contact with at least a portion of the
cushion suspension springs 118. Any elevational
movement of the cushion suspension springs will result :
in elevational movement of the leaf spring 134.
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A plurality of electrical wire leads 168 are
connected at an end of the switch 124. The other end
of the leads 168 are connected to an electrical vehicle
system. The electrical vehicle system is therefore
operative in response to the s~itch being in one of the
open and closed positions and inoperative in response
to the switch being in the other of the open and closed
positions.
Industrial Applicability
Referring to the preferred embodiment of Fig.
1, the seat assembly 10 is shown in the unloaded
position, i.e. without a vehicle operator seated
thereon. In this position the resilient member 32
maintains the gap 38 between the lower surface 34 of
the connecting frame 18 and the upper surface 36 of the
support frame 12 at a maximum by urging i:he connecting
frame 18 about the pivot pin 30 away from the support
frame 12. At this position the first end portion 46 of
the actuating spring 44 is spaced from contact with the
plunger 64 of switch 42 and the switch 42 is in one of
the open and closed positions. In this position, the
vehicle system is conditioned to prevent the vehicle
from travel, for example, by applying a brake,
neutralizing a transmission or disabling a prime mover.
When a load is applied to the seat 14 of the
seat assembly 10 the load will cause the seat assembly
10 to pivot about pin 30 in a direction toward the
support frame 12~ This pivotal motion will cause the
connecting frame and more importantly second end
portion 26 of the connecting frame 18 to move toward
the support frame 12 by compressing the resilient
member 32 a variable amount as determir-ed by the load
placed upon the seat 14. The actuator spring 44, of
the actuator assembly 40, being attached to the
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connecting frame 18 will move in its entirety with the
connecting frarne until the first end portion 46 of the
actuator spring 44 contacts and forceably depresses the
plunger 64 of the switch for actuating the switch 42 to
the o-ther of the open and closed positions. In this
position the vehicle system woulcl be conditioned to
permit vehicle movement, It is to be noted -that the
force applied to the switch is proportional to the load
on the seat 14 but substantially less than the load,
Further movement of the connecting frame 18 of
the seat assembly 10 toward the support frame 12,
subsequent to depression of the plunger 64 and
actuation of the switch 42 will result in no movement
of the first end portion 46 of the actuator spring
relative to the switch 42 as the second end portion 48
moves with the connecting frame 18. Both the first end
portion 46 of the actuator spring 44 and the resilient
bracket 56 supporting the switch 42 will move together
slightly when the force applied to the switch 42 by the
first end portion 46 of the actuator spring reaches a
preselected magnitude which is substantially less than
the load applied to the seat assembly. This will
prevent excessive loading of the switch and reduce
premature failure thereofO
The spring 44 of the actuator assembly 40 also
acts to resist cyclical actuation of the switch 42 due
to oscillation of the seat assembly and its load caused
by the vehicle operating over rough terrain. The
actuator spring 44 is adjustable between spaced
elevational positions relative to the connecting frame
by the adjusting screw 54. This permits the first end
portion 46 of the actuator spring to be pos;tioned
elevationally relative to the switch 42 to establish a
minimum force on the seat 14 at which the plunger 64 is
contacted and the switch 42 actuated. This minimum
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seat force is substantially less than the averageweight of an operator and therefore any slight
elevational movement of the connecting frame due to
bouncing will not deactivate the switch and prevent the
vehicle from travelling.
It is to be noted that the wire leads 66 from
the switch 42 to the vehicle system encounter
substantially very little movement during operation of
the vehicle and with the seat 14 occupied. Thus
failure due to wire breakage will be lessened.
Referring to the alternate embodiment of Figs.
2 and 3, the seat assembly 110 and actuating apparatus
122 is shown in an unloaded position in solid lines and
in a loaded position in phan-tom lines.
In the unloaded position, i.e. the vehicle
operator is not seated thereon, the seat 114 and
cushion support spring 118 are at an undeflected
elevational position and the first end portion 128 of
the actuator spring 126 is spaced from contact with the
plunger 150. Therefore, the switch is in one of the
open and closed positions and the electrical vehicle
system is conditioned to prevent the vehicle from
travel such as, for e~ample, by applying a brake,
neutralizing a transmission or disabling a prime mover.
When a load is applied to the seat 114 of the
seat assembly 110 the weight of the load will cause the
cushion suspension springs 118 to deflect toward the
support frame 112. The change in the elevational
position of the cushion suspension springs 118 ~
result in equivalent elevational movement of the middle
portion 132 of the actuator spring 126 of the actuator
apparatus 122 since the middle portion 132 and
specifically the upper surface 136 is in continuous
contact with at least a portion of the seat suspension
spring 118. This elevational movement of the middle
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portion 132 will cause both the first and second end
portions 128,130 of the actuator spring 126 to move in
a predetermined proportional manner. The second end
portion 130 will move elevationally but will also
deflect outwardly as the curvalinear portion 164 slides
along the surface 166 to a location determined by the
load placed on the seat assembly 110. Such a location
is shown by phantom lines on Fig. 2. The first end
portion 128 will also move, however, in a different
manner. Since the first end portion 128 is piv~tly
connected to pivot pin 138 deflection of the actuator
spring toward the support frame 112 will result in
pivotal movement of the first end portion 128 about the
pivot pin 138 toward the switch 124. This movement
will result in forceable engagement of the plunger 150
and translation thereof. It is to be noted that this
construction eliminates inadvertent cyclical actuation
of the switch by isolating the switch 124 from direct
contact with the seat assemblyO Thus, the switch will
be actuated to the other of the open and closed
positions at which the electrical vehicle system is
conditioned to permit vehicle travel such as by
releasing the brake, engaging the transmission or
enabling the prime mover.
The stop 160 has been provided to limit the
amount of pivotal movement of the first end portion 128
of the actuator spring 126. Since the force applied to
the plunger 150 and ultimately the switch 124 by the
first end portion 128 of the actuator assembly is less
than the weight of the load on the seat assembly 110
but proportional thereto it is necessary to establish a
maximum force limit. This is achieved by placing a
limit on the permissible amount of pivotal movement the
first end portion 128. When the load on the seat
reaches a preselected maximum magnitude, the deflection
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of the cushion suspension spring 118 and the actuator
spring 122 will force the actuator spring closely
adjacent the first end portion 128 of the actuator
spring to pivot about pin 138 until it engages the stop
160. Further deflection of the actuator spring 122 due
to loads in excess of the preselected maximum magnitude
will not result in additional pivotal motion of the
first end portion 128 on either side of the pin 138 and
therefore the force on the switch will be limited.
The minirnum force required to actuate the
switch 124 by depressing the plunger 150 is deterrnined
by adjusting the position of the switch 124 relative to
the first end portion 128 of the actuator spring 126.
This is achieved by rotating the adjusting screw 152
which pivotly moves the switch 124 about fastener 143.
It is to be noted that the switch 124 does not
move under normal operation and therefore the elctrical
wire leads 168 are not subjected to flexing and the
like.
Therefore, the embodiments herein described
eliminate over stressing of the electrical switch and
premature switch failure, inadvertent cyclical switch
actuation, and electrical wire brealcage.
Other aspects, objects and advantages of the
invention can be obtained from a study of the drawings,
disclosure and appended claims.
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