Note: Descriptions are shown in the official language in which they were submitted.
CA 02495472 2005-O1-28
BACKGROUND OF THE INVENTION:
The invention pertains generally to linear transfer devices. More specifically
to linear
transfer devices utilizing a combination of an electric motor and a
longitudinal member
such as a rod, rail, cable, shaft etc. to convert rotational motion of the
motor into linear
motion.
The principles behind the operations of a conventional electric motor Fig 1
are well known.
A typical conventional motor consists of an axle which serves as the main
shaft of rotation,
a commutator to control current flow, copper wire to generate electromagnetic
fields in the
armature, permanent magnets (or electromagnets) to attract/repel the
electromagnets of
the armature, the contents of which are housed in a motor housing. When
current is
applied the motor turns around the axis of rotation of the axle. This is
rotational motion. To
change rotational motion into linear motion engineering has relied on the use
of gears,
pulleys, cables, sliding devices etc which are expensive to manufacture and
challenging to
house. This current invention converts rotational motion of the axle of the
electric motor
through the tapped core of the axle directly into linear motion along a
threaded rod thus
causing the motor to travel in a to-and-fro motion in a linear path or curved
path along the
threaded rod. Thus the invention is simple, consists of very few parts, is
small and easily
packaged in small-space applications, it is compact and inexpensive to
manufacture. One
additional advantage is in this invention's ability to produce motion not only
along a straight
line but also along a curved path.
It can thus be seen that the present invention provides a novel, superior and
inexpensive
method for converting rotational motion into linear motion.
CA 02495472 2005-O1-28
SUMMARY OF THE INVENTION:
The invention pertains to a linear transfer device for the purpose of
converting rotational
motion of an electric motor (or pneumatic motor) into motion along a straight
line or a
curved path. The said invention comprises a conventional reversible electric
motor with a
hollow tapped core extending the full length of the axle through which a
threaded rod wilt
pass entering at one end of the axle, through the full length of the axle, and
out the other
end of the axle and beyond the electric motor.
The threaded rod is secured so that it cannot move in any direction, and the
threaded rod
cannot rotate along its longitudinal axis. The motor housing containing the
tapped-axle is
secured such that the motor housing cannot rotate about the axis of the tapped-
axle,
however the motor can move in a linear direction along the threaded rod.
Conversion of
rotational motion into linear motion is obtained at the point where the
treaded rod engages
the tapped-axle of the motor.
When current is applied to the electric motor, the axle rotates causing the
entire electric
motor to advance in either direction along the threaded rod which passes
through the axle.
If the length of the tapped-axle is sufficiently short, or the length of the
tap along the inner
core of the axle is sufficiently short, movement can be obtained along a
curved path. The
invention is of significant benefit since it is small, consists of very few
parts, does not rely
on reduction gears, belts, cables, pulleys etc and is very cost effective to
manufacture.
CA 02495472 2005-O1-28
DESCRIPTION OF PRIOR ART:
It is known in the prior act to provide a linear transfer device comprising an
electric motor
and a threaded rod to convert rotary motion of the motor into linear motion
along the
threaded rod. For instance U.S. Patent number 6,453,761 (inventor Babinski,
Sept
24/2002) and U.S. Patent number 5,899,114 (inventor Dolata May 4/1999), which
rely on a
helical rod entering a nut-like motor cavity, a complex ball-circuit raceway,
a re-circulation
of balls, and the motor stands still while the rod moves.
In a different application, U.S. patent number 5,622,251 (inventor Rantanen
April 22, 1997)
relies on a stationary electric motor, a straight threaded rod, a tapped nut
and
accompanying brackets and guiding rods to accompany linear travel, limitations
include
high manufacturing costs and linear travel in a straight line only.
In an interesting design, US Patent number 4,560,894 (Stoll Dec 24/1985), a
concentric
tap running on the outside of the armature of the electric motor is mated with
a threaded
rod of a sliding unit, however the mechanism is limited in travel length no
greater than the
length of the motor and linear movement is limited to straight line travel
only.
It is clear that the present invention presents a novel, versatile and low
cost solution to the
need for converting rotational motion of an electric motor into movement along
a straight
path or curved path which the above mentioned patents fail to provide.
CA 02495472 2005-O1-28
BRIEF DESCRIPTION OF THE DRAWINGS:
Fig-1: Conventional Electric Motor
Fig-2: Invention: New Electric motor having a concentric hollow and tapped
center
extending the full length of the motor axle and threaded rod
Fig-3: A cross section of Fig 2 along plane FF showing the tapped axle
Fig-4: A cross section of Fig 2 along plane FF showing a straight threaded rod
fed through
the tapped axle
Fig-5: A cross section of Fig 2 along plane FF showing the axle with a shorter
tapped core
for use on curved threaded rods
Fig-6: A cross section of Fig 2 along plane FF showing a curved threaded rod
fed through
the tapped axle
Fig-7: A cross section illustrating how the threaded rod is to be immobilized
in order to
prevent rotation of the rod during motor travel
Fig-8: Illustrates how the invention can be applied to serve as a vehicle
window regulator
Fig-9: Illustrates a cross section of a tapped-axle having a concentric
profile to suit the
curvature of the curved rod
Fig-10: Illustrates a cross section of a tapped-axle's internal curved profile
Fig-11: Illustrates an insert to be housed inside a hollow axle where said
insert replaces
the tap for engaging the curved threaded rod
Fig-12: 111ustrates said insert of Fig-11 housed inside said hollow axle and
engaged by a
curved threaded rod
CA 02495472 2005-O1-28
-1-
DESCRIPTION OF THE PREFERRED EMBODIMENT:
Fig-1 illustrates the design of the conventional electric motor (10) and the
modification to the conventional motor to create the tapped-axle motor (12) in
Fig-2
which in cooperation with the threaded rod (8) comprises a transfer device for
performing linear transfer movement along a straight path or along a curved
path.
Fig-1 illustrates the design of the conventional electric motor including the
axle (1 ),
the commutator (2), copper wiring (3), armature (4), permanent magnet (5),
motor
housing (6) and an axis of rotation (AA) along the axle (1) allowing for
direction of
rotation (B) and (C) of the axle (1 ).
Fig-2 illustrates the modification to the conventional electric motor. Note
the solid
axle (1) of Fig-1 is replaced with an axle having a hollow core (7b)
concentric to the
axis of rotation FF and said hollow core is tapped such that a matching
threaded rod
(8) will pass through the tapped-axle (7) and extend beyond both ends of the
electric
motor. When the tapped-axle motor (12) is engaged, rotational movement of the
tapped-axle (7) in the direction D and E is transformed into linear movement
along
the threaded rod (8) in the direction G and H.
Fig-3 is an illustration of the cross section of the tapped-axle motor (12) of
Fig-2
along (FF). Note the tapped-axle (7) is hollow throughout the full length of
the axle
and the tap (14) itself is concentric and internal to the tapped-axle (7). The
diameter
of the axle (13), the tap size (14), the length of tapping distance (15) will
vary with the
application depending on strength requirement, torque necessary to move the
load,
travel speed etc. required by the transfer device. Also concentric bearings
(11A) and
(11 B) are mounted to separate the tapped-axle (7) and the motor housing (9)
as well
as reduce component wear during motor travel.
Fig-4 illustrates a straight threaded rod (8) passing through the full length
of the
tapped-axle (7) of the tapped -axle motor (12).
Fig-5 illustrates how the tapped-axle (7) would be adapted to suit a curved
threaded
rod (16) passing through the tapped-axle motor (12). Note the tapping distance
(15)
is reduced to minimize the points of contact between the tapped-axle (7) and
the
curved threaded rod (16). The hollow axle-core (17a) and (17b) is the part of
the
tapped-axle (7) that is not tapped but is of greater diameter than the tap
diameter to
CA 02495472 2005-O1-28
-2-
allow the curved threaded rod (16) to pass uninhibited. Also thread separation
of fine
or coarse thread, hollow axle-core diameter (17c), tap size, tapping distance
(15) will
be selected to allow the curved threaded rod (16) to pass uninhibited. Note
that
although the curved-threaded-rod (16) is in fact curved over a large distance,
the
curved rod (16) over a length equal to the tapped distance (15) of the tapped-
axle (7)
is almost straight, hence with minimal play between the tap and the thread the
tapped-axle motor (12) can advance along a curved rod (16).
Fig-6 illustrates how a curved threaded rod (16) would fit through the tapped-
axle
motor (12). Note that the treaded rod (16) only engages the tapped-axle (7)
along the
tapped distance (15) and the hollow axle core (1Ta) and (17b) do not engage
the
curved threaded rod (16).
Fig-7 illustrates that the threaded rod is secured at either or both ends with
a stopper
(17) such that the straight threaded rod (8) or curved threaded rod (16) is
immobilized
by the stopper (17).
A guide-clamp (18) is secured to the tapped-axle motor housing (9) to prevent
the
motor housing (9) from spinning around the threaded rod (8) when the motor is
engaged. The guide clamp (18) may be guided along a guide (19) to allow
movement
of the tapped-axle motor (12) in the direction (G) and (H) along the length of
the
threaded rod (8) or (16).
Fig-8 illustrates how an automotive window regulator would apply this
invention. A
car window (23) guided along a window frame (21 ) is attached to the tapped-
axle
motor housing (9) by way of attachment units (20) and (22). Thus the window
(23)
would prevent the tapped-axle motor (12) from spinning around the threaded rod
(8).
The tapped-axle motor (12) and the car window (23) travel along the straight
threaded rod (8) or curved threaded rod (16) in the direction (G) and (H).
Fig-9 illustrates a cross-section of a particularly curved threaded (16) rod
entering the
tapped-axle (7) where the tapped-axle's axis of rotation (24) is linear, but
the axis of
the curved threaded rod (16) has a curved profile (25).
Fig-10 illustrates a cross section of a tapped-axle core having a concentric
axis (24)
and a curved profile of the tapped core (26a) and (26b) in an effort to
eliminate
jamming of the transfer device when penetrated by a threaded rod.
CA 02495472 2005-O1-28
-3-
Fig-11 illustrates a helical insert (27) comprising a mounting member (28) and
extending in both directions are flexible helical spiral prongs (29) and (30).
The
helical insert engages the curved threaded rod (16) in a nut-and-screw method,
the
spiral prongs (29) and (30) are flexible and bend to follow the contour of the
threaded
rod (16) as in Fig-12. The helical insert (27) is concentrically fitted in the
hollow core
of the axle (7b) in place of the tap. The helical insert (27) is used in
applications
where the curvature of the threaded rod (16) is significant such that the use
of a tap
inside the axle is not practical.
