Title of Invention	DOUBLE-SIDED SLIDING BUTTON FOR USE IN A REVERSIBLE DRIVEN PULLEY
Abstract	The double-sided sliding button (10) comprises two spaced-apart sliding button halves (20). Each half (20) has a front side (22), provided with a contact surface (26), and a rear side (24). Both contact surfaces (26) are mutually opposite and both front sides (22) of each half (20) intersect the curved medial axis (M). A bridge member (30) connects the two halves (20) together. With this configuration, each sliding button (10) can be easily installed and secured in a clamp (100) attached to a part of a reversible driven pulley of a continuously variable transmission (CVT). Each double- sided sliding button (10) is capable of working in both directions, thereby reducing the number of individual sliding buttons to be installed by 50%.

Title of Invention

DOUBLE-SIDED SLIDING BUTTON FOR USE IN A REVERSIBLE DRIVEN PULLEY

Abstract

The double-sided sliding button (10) comprises two spaced-apart sliding button halves (20). Each half (20) has a front side (22), provided with a contact surface (26), and a rear side (24). Both contact surfaces (26) are mutually opposite and both front sides (22) of each half (20) intersect the curved medial axis (M). A bridge member (30) connects the two halves (20) together. With this configuration, each sliding button (10) can be easily installed and secured in a clamp (100) attached to a part of a reversible driven pulley of a continuously variable transmission (CVT). Each double- sided sliding button (10) is capable of working in both directions, thereby reducing the number of individual sliding buttons to be installed by 50%.

Full Text	DOUBLE-SIDED SLIDING BUTTON FOR USE IN A REVERSIBLE DRIVEN PULLEY Continuously variable transmissions (CVTs) are commonly used on a wide range of vehicles, such as small cars or trucks, snowmobiles, golf carts, scooters, etc. They typically comprise a driving pulley mechanically connected to a motor, a driven pulley mechanically connected to wheels or a track, possibly through another mechanical device such as a gear box, and a trapezoidal drivebelt transmitting torque between the driving pulley and the driven pulley. A CVT automatically changes the ratio as required by load and speed conditions, providing an increased torque under high load and speed conditions, providing an increased torque under high loads at low speeds and yet controlling the rotation speed of the motor as the vehicle accelerates. A CVT may be used with all kinds of motors, such as internal combustion engines or electric motors. The sides of the drivebelt are, on each pulley, gripped between two opposite sheaves that are coaxially mounted around a corresponding main shaft. Generally, in each pulley of a conventional CVT, one sheave, usually called "fixed sheave", is rigidly connected to one end of the corresponding main shaft. The other sheave, usually called "movable sheave", is free to slide and / or rotate with reference to the fixed sheave since it is mounted on bushings or the like. At a low vehicle speed, the winding diameter of the drivebelt at the driving pulley is minimal and the winding diameter at the driven pulley is maximum. This is referred to as the minimum ratio since there is the minimum number of rotations or fraction of rotation of the driven pulley for each full rotation of the driven pulley. Generally, when the rotation speed of the driving pulley increases, its movable sheave moves closer to the fixed sheave thereof under the effect of a centrifugal mechanism. This forces the drivebelt to wind on a larger diameter on the driving pulley and, consequently, on a smaller diameter on the driven pulley. The drivebelt then exerts a radial force on the sheaves of the driven pulley in addition to the tangential driving force by which the torque is transmitted. This radial force urges the movable sheave of the driven pulley away from the fixed sheave thereof. It is counterbalanced in part by a return force, which is typically generated by a spring inside the driven pulley or another biasing mechanism. It is also counterbalanced by a force generated by the axial reaction of the torque applied by the drivebelt on the driven pulley. This is caused by a cam system that tends to move the movable sheave towards the fixed sheave as the torque increases. The cam system typically comprises a cam plate having a plurality of symmetrically- disposed and inclined ramps on which respective cam followers are engaged. The followers are usually sliding buttons or rollers. The set of ramps or the set of followers is mounted on the movable sheave and the other is directly or indirectly connected to the main shaft in a rigid manner. The closing effect of the cam system on the drivebelt tension is then somewhat proportional to output torque. Generally, at the maximum vehicle speed, the ratio is maximum as there is the maximum number of rotations or fraction of rotation of the driven pulley for each full rotation of the driving pulley. Then, when the vehicle speed decreases, the rotation speed of the driving pulley typically decreases as well since the rotation speed of the motor decreases. This causes, at some point, a decrease of the winding diameter of the driving pulley and a decrease of the radial force exerted by the drivebelt on the sides of the sheaves at the driven pulley. Ultimately, the driven pulley is allowed to have a larger winding diameter as the spring or another biasing mechanism moves the movable sheave towards the fixed sheave. Some CVTs are provided with reversible driven pulleys. A reversible driven pulley operates in a similar fashion than that of a unidirectional one, with the exception that the transmission ratio can be controlled during motor braking or when the vehicle is traveling in reverse. For instance, during motor braking, the torque is no longer coming from the motor to the wheels or track, but in the opposite direction. Similarly, when accelerating in reverse, the torque and the rotation will be in the reverse direction, the torque being transmitted from the motor to the wheels or track. A reversible driven pulley generally comprises a second set of ramps and a second set of followers. In use, one set of followers and its corresponding set of ramps are used when the torque is in one direction, the other set being used for the other direction. U.S. patent No. 6,413,178, issued on 2 July 2002 to Rene CHAMBERLAND, discloses a reversible driven pulley having cam followers disposed side-by- side and aligned in a radial plane of the pulley. The cam followers are mounted on a radial support. As can be seen from the foregoing, reversible driven pulleys must have two sets of followers, one being required for each set of ramps. Each of these followers must be secured at a corresponding location in the driven pulley. The attachment of the followers is particularly important since they are subjected to very important stresses when the driven pulleys are in operation. When the followers are sliding buttons, one must be able to easily remove them and replace them with new ones since they usually wear over time. There was thus a need to provide a sliding button having a new configuration and design which is more convenient and efficient than the conventional ones, particularly for reversible driven pulleys where the number of sliding buttons is important. Accordingly, there is provided a double-sided sliding button for use in a reversible driven pulley. The sliding button comprises two spaced-apart sliding button halves which are configured and disposed with reference to a curved medial axis substantially inscribed in a radial plane of the pulley. Each half has a front side, provided with a contact surface, and a rear side. Both contact surfaces are mutually opposite and both sides of each half intersect the curved medial axis. A bridge member allows to rigidly connect the rear side of the two halves. With this configuration, each sliding button can be easily installed and secured in a clamp attached to a part of driven pulley. Each sliding button is also capable of working in both directions, thereby reducing the number of individual sliding buttons to install by 50%. Accordingly, the present invention provides a double-sided sliding button for use in a reversible driven pulley, the sliding button comprising : two spaced-apart sliding button halves configured and disposed with reference to a curved medial axis, each half having a front side, provided with a contact surface, a rear side and a bottom side, both contact surfaces being mutually opposite and both front sides intersecting the curved medial axis; and a bridge member rigidly connected to the rear side of the two halves. Other aspects and advantages of the present invention are described in or apparent from the following detailed description of a preferred embodiment made in conjunction with the accompanying figures, in which : FIG. 1 is a side elevation view of the sliding button in accordance with a preferred embodiment of the present invention; FIG. 2 is a bottom view of the sliding button shown in FIG. 1; FIG. 3 is an exploded perspective view of the double-sided sliding button shown in FIG. 1 and a corresponding supporting clamp; FIG. 4 is an perspective view of the resulting assembly of the sliding button and the clamp shown in FIG. 3. FIG. 5 is a cross-section view taken along line V-V in FIG. 4. FIG. 6 is a schematic top cross-sectional view of the sliding button mounted in its supporting clamp, showing the forces involved. FIG. 7 is a schematic side cross-sectional view similar to that of FIG. 6. FIG. 8 is a schematic side view showing two opposite ramps and a double- sided sliding button. FIG. 9 is a view similar to FIG. 6, showing another position for the sliding button. Throughout the figures, analogous components are identified by the same reference numerals. Some parts which are not referred to correspond to the same components shown in preceding figures. The following is a list of reference numerals, along with the names of the corresponding components, which are used in the description and in the accompanying figures. 10 Double-sided sliding button 20 Half (of the sliding button 10) 22 Front side (of each half 20) 24 Rear side (of each half 20) 25 Bottom side (of each half 20) 26 Contact surface (of each half 20) 28 Flange (of each half 20) 30 Bridge member 32 Sleeve portion (of the bridge member 30) 100 Clamp 110 Central section (of the clamp 100) 112 Flange (of the clamp 100) 114 Slot (of the clamp 100) 116 Threaded bore (in the central section 110) 120 Side sections (of the clamp 100) 130 Radial slots (of the clamp 100) 140 Screw 200 Ramps M Curved medial axis FIGS. 1 to 9 show a double-sided sliding button (10) in accordance with a preferred embodiment of the present invention. The double-sided sliding button (10) is shown with the preferred embodiment for a corresponding clamp (100) used to attach the sliding button (10). These parts are to be installed in a reversible driven pulley. Like the other components of a driven pulley, the sliding button (10) and the clamp (100) are configured and disposed to be symmetrical with reference to the rotation axis of the driven pulley. This also allows the driven pulley to remain balanced when rotating. The sliding button (10) is constructed with reference to a curved medial axis (M). The center of the curved medial axis (M) is preferably the rotation axis of the driven pulley. The driven pulley has one sheave which is able to slide and rotate with reference to the other sheave. The sliding buttons (10) are then mounted on one of these sheaves. Corresponding ramps (200) are mounted on the other sheave. The ramps (200) are curved as well. As can be seen, the sliding button (10) comprises two spaced-apart sliding button halves (20). Each half (20) is in fact a sliding button corresponding to one of the ramps (200). Both halves (20) are not necessarily identical since they are used in different contexts. For instance, when the vehicle travels in reverse, the response of the driven pulley do not need to be the same compared to when the vehicle travels in a forward direction. The shape of the ramps (200) of each set also changes as well. Each half (20) has a front side (22), a rear side (24) and a bottom side (25). The front side (22) is provided with a contact surface (26), which contact surface (26) is shaped in accordance with the design requirement and to maintain a good contact with the corresponding ramp (200). Examples of ramps (200) are shown in FIGS. 8 and 9. The contact surface (26) defines a three-dimensional curve, or helix, which is matched by an opposite curve on the surface of a corresponding ramp (200). As best shown in FIG. 2, both contact surfaces (26) of the sliding button (10) are mutually opposite and both front sides (22) intersect the curved medial axis (M). A bridge member (30) is used to maintain together the two sliding button halves (20). This bridge member (30) is rigidly connected to the rear side (24) of the two sliding button halves (20). The bridge member (30) is preferably aligned with the curved medial axis (M), although it could also be located elsewhere, for instance closer to an edge of the sliding button halves (20). It also preferably comprises a sleeve portion (32) having a center axis extending substantially parallel to the rear side (24) of the sliding button halves (20). Preferably, each half (20) further comprises a flange (28) projecting from the bottom side (25). These flanges (28) allow to tightly secure the sliding button (10) in place. Each flange (28) is adjacent to the rear side (24) of the corresponding half (20) and extend parallel thereto. The purpose of these flanges (28) will be explained hereafter. The clamp (100) used to hold the sliding button (10) is preferably T- shaped, as shown in FIG. 3. Other configurations can be used as well. The clamp (100) is generally curved and aligned with the curved medial axis (M). It comprises a central section (110) and two opposite side sections (120). The central section (110) and the side sections (120) are preferably separated by radial slots (130). The central section (110) of each clamp (100) comprises opposite and spaced- apart flanges (112). The two flanges (112) define between them a slot (114) between which the bridge member (30) of the sliding button (10) will be inserted. Furthermore, as shown in FIG. 5, a threaded bore (116) is provided in the central section (110) in order to receive the free end of a screw (140) designed to secure the sliding button (10) in place. It should be noted that the screw (140) can be replaced by any other equivalent connector. The design of the parts is such that the sliding button (10) should fit snugly and tightly into the clamp (100), as shown in FIG. 4. This insures that the forces are properly balanced and that the sliding button (10) remains in place. The projecting flanges (28) of the sliding button (10) then extend into the radial slots (130) of the clamp (100) with an interfering engagement. The flanges (28) preferably comprise a plurality of bosses which allow to facilitate the insertion of the flanges (28) in their respective radial slot (130). FIGS. 6 and 7 show the forces involved when the sliding button which is installed in the clamp (100). As can be seen, the sides of the central section (110) are preferably slightly inclined and define between them an angle 9i. Since the rear sides (24) of the halves (20) are parallel, the insertion of the sliding button (10) into the clamp (100) induces pressing forces on the sides of the central section (110). These forces are referred to as F-, and F2 in FIG. 6. These forces are also shown in FIG. 7. It should be noted that the design should not be such that the sliding button (10) will have a tendency to come out of the clamp (100) by itself. Nevertheless, the screw (140) (shown in FIG. 7) produces a force F3 which maintains the sliding button (10) in place. As can also be seen in FIG. 6, the two flanges (28), located in the radial slots (130), are designed to apply two opposite forces, referred to as F4 and F5. These forces allow to maintain the bottom side (25) of each half (20) against the side sections (120). Forces F6 and F7 are then applied by the bottom sides (25). All this prevents the half (20) to be lifted from the corresponding side section (120) when the contact surface (26) of the opposite half (20) is engaged against a corresponding ramp (200). As can be seen from FIG. 7, the sides of the flanges (112) of the central section (110) are separated by an angle 92 which is slightly greater than the distance between the two halves (20). This creates forces Fs and Fq which press the inner side of the sliding button (10) against the structure to which the clamp (100) is attached. Such structure can also be seen in FIG. 5. This also promotes stability of the sliding button (10) when it is in use. Among other things, it prevents the inner side of each half (20) from detaching from the adjacent wall under the effect of the elastic forces F10 and F-h created by the slight stretching of the bridge (30). FIGS. 8 and 9 schematically show how the sliding button (10) can move while it is in use. During normal use, the contact surface (26) of one sliding button half (20) is in engagement with the corresponding ramp (200). When the direction of the torque changes to the point that this can no longer be compensated by the spring of the driven pulley, the sliding button (10) changes position and is moved towards the opposite ramp (200). This transition period is usually very short. If desired, a damping element (not shown) can be provided between the sliding button (10) and the clamp (100) in order to decrease the shocks caused when the sliding button (10) hits the opposite ramp (200). As can be appreciated, the double-sided sliding button (10) has many advantages compared to single sliding buttons for reversible driven pulleys. Among other things, the double-sided sliding button (10) can be easily installed and secured in a clamp attached to a part of the driven pulley The number of individual sliding buttons is also reduced by 50%. WE CLAIM : 1. A double-sided sliding button (10) for use in a reversible driven pulley, the sliding button (10) comprising : two spaced-apart sliding button halves (20) configured and disposed with reference to a curved medial axis (M), each half (20) having a front side (22), provided with a contact surface (26), a rear side (24) and a bottom side (25), both contact surfaces (26) being mutually opposite and both front sides (22) intersecting the curved medial axis (M); and a bridge member (30) rigidly connected to the rear side (24) of the two halves (20). 2. The double-sided sliding button (10) as claimed in claim 1, wherein the bridge member (30) is aligned with the medial axis (M). 3. The double-sided sliding button (10) as claimed in claim 2, wherein the bridge member (30) comprises a sleeve portion (32) having a center axis extending between to the rear side (24) of the halves (20). 4. The double-sided sliding button (10) as claimed in any one of claims 1 to 3, wherein each half (20) has a flange (28) projecting from the bottom side (25) and extending parallel to the rear side (24) of the half (20). 5. The double-sided sliding button (10) as claimed in claim 4, wherein the rear side (24) is flat. 6. The double-sided sliding button (10) as claimed in any one of claims 1 to 5, wherein the halves (20) and the bridge member (30) are integrally connected in a one-piece molded plastic item. The double-sided sliding button (10) comprises two spaced-apart sliding button halves (20). Each half (20) has a front side (22), provided with a contact surface (26), and a rear side (24). Both contact surfaces (26) are mutually opposite and both front sides (22) of each half (20) intersect the curved medial axis (M). A bridge member (30) connects the two halves (20) together. With this configuration, each sliding button (10) can be easily installed and secured in a clamp (100) attached to a part of a reversible driven pulley of a continuously variable transmission (CVT). Each double- sided sliding button (10) is capable of working in both directions, thereby reducing the number of individual sliding buttons to be installed by 50%.

Full Text

DOUBLE-SIDED SLIDING BUTTON FOR USE IN A REVERSIBLE DRIVEN PULLEY
Continuously variable transmissions (CVTs) are commonly used on a wide range of vehicles, such as
small cars or trucks, snowmobiles, golf carts, scooters, etc. They typically comprise a driving pulley
mechanically connected to a motor, a driven pulley mechanically connected to wheels or a track,
possibly through another mechanical device such as a gear box, and a trapezoidal drivebelt
transmitting torque between the driving pulley and the driven pulley. A CVT automatically changes
the ratio as required by load and speed conditions, providing an increased torque under high load and
speed conditions, providing an increased torque under high loads at low speeds and yet controlling
the rotation speed of the motor as the vehicle accelerates. A CVT may be used with all kinds of
motors, such as internal combustion engines or electric motors.
The sides of the drivebelt are, on each pulley, gripped between two opposite sheaves that are
coaxially mounted around a corresponding main shaft. Generally, in each pulley of a conventional
CVT, one sheave, usually called "fixed sheave", is rigidly connected to one end of the corresponding
main shaft. The other sheave, usually called "movable sheave", is free to slide and / or rotate with
reference to the fixed sheave since it is mounted on bushings or the like.
At a low vehicle speed, the winding diameter of the drivebelt at the driving pulley is minimal and the
winding diameter at the driven pulley is maximum. This is referred to as the minimum ratio since
there is the minimum number of rotations or fraction of rotation of the driven pulley for each full
rotation of the driven pulley.
Generally, when the rotation speed of the driving pulley increases, its movable sheave moves closer
to the fixed sheave thereof under the effect of a centrifugal mechanism. This forces the drivebelt to
wind on a larger diameter on the driving pulley and, consequently, on a smaller diameter on the
driven pulley. The drivebelt then exerts a radial force on the sheaves of the driven pulley in addition
to the tangential driving force by which the torque is transmitted. This radial force
urges the movable sheave of the driven pulley away from the fixed sheave thereof.
It is counterbalanced in part by a return force, which is typically generated by a
spring inside the driven pulley or another biasing mechanism. It is also
counterbalanced by a force generated by the axial reaction of the torque applied
by the drivebelt on the driven pulley. This is caused by a cam system that tends to
move the movable sheave towards the fixed sheave as the torque increases. The
cam system typically comprises a cam plate having a plurality of symmetrically-
disposed and inclined ramps on which respective cam followers are engaged. The
followers are usually sliding buttons or rollers. The set of ramps or the set of
followers is mounted on the movable sheave and the other is directly or indirectly
connected to the main shaft in a rigid manner. The closing effect of the cam
system on the drivebelt tension is then somewhat proportional to output torque.
Generally, at the maximum vehicle speed, the ratio is maximum as there is the
maximum number of rotations or fraction of rotation of the driven pulley for each
full rotation of the driving pulley. Then, when the vehicle speed decreases, the
rotation speed of the driving pulley typically decreases as well since the rotation
speed of the motor decreases. This causes, at some point, a decrease of the
winding diameter of the driving pulley and a decrease of the radial force exerted by
the drivebelt on the sides of the sheaves at the driven pulley. Ultimately, the
driven pulley is allowed to have a larger winding diameter as the spring or another
biasing mechanism moves the movable sheave towards the fixed sheave.
Some CVTs are provided with reversible driven pulleys. A reversible driven pulley
operates in a similar fashion than that of a unidirectional one, with the exception
that the transmission ratio can be controlled during motor braking or when the
vehicle is traveling in reverse. For instance, during motor braking, the torque is no
longer coming from the motor to the wheels or track, but in the opposite direction.
Similarly, when accelerating in reverse, the torque and the rotation will be in the
reverse direction, the torque being transmitted from the motor to the wheels or
track. A reversible driven pulley generally comprises a second set of ramps and a
second set of followers. In use, one set of followers and its corresponding set of
ramps are used when the torque is in one direction, the other set being used
for the other direction.
U.S. patent No. 6,413,178, issued on 2 July 2002 to Rene CHAMBERLAND,
discloses a reversible driven pulley having cam followers disposed side-by-
side and aligned in a radial plane of the pulley. The cam followers are
mounted on a radial support.
As can be seen from the foregoing, reversible driven pulleys must have two
sets of followers, one being required for each set of ramps. Each of these
followers must be secured at a corresponding location in the driven pulley.
The attachment of the followers is particularly important since they are
subjected to very important stresses when the driven pulleys are in
operation. When the followers are sliding buttons, one must be able to
easily remove them and replace them with new ones since they usually wear
over time. There was thus a need to provide a sliding button having a new
configuration and design which is more convenient and efficient than the
conventional ones, particularly for reversible driven pulleys where the
number of sliding buttons is important.
Accordingly, there is provided a double-sided sliding button for use in a
reversible driven pulley. The sliding button comprises two spaced-apart
sliding button halves which are configured and disposed with reference to a
curved medial axis substantially inscribed in a radial plane of the pulley.
Each half has a front side, provided with a contact surface, and a rear side.
Both contact surfaces are mutually opposite and both sides of each half
intersect the curved medial axis. A bridge member allows to rigidly connect
the rear side of the two halves. With this configuration, each sliding button
can be easily installed and secured in a clamp attached to a part of driven
pulley. Each sliding button is also capable of working in both directions,
thereby reducing the number of individual sliding buttons to install by 50%.
Accordingly, the present invention provides a double-sided sliding button for use in a
reversible driven pulley, the sliding button comprising : two spaced-apart sliding button halves
configured and disposed with reference to a curved medial axis, each half having a front side,
provided with a contact surface, a rear side and a bottom side, both contact surfaces being mutually
opposite and both front sides intersecting the curved medial axis; and a bridge member rigidly
connected to the rear side of the two halves.
Other aspects and advantages of the present invention are described in or apparent from the
following detailed description of a preferred embodiment made in conjunction with the
accompanying figures, in which :
FIG. 1 is a side elevation view of the sliding button in accordance with a preferred
embodiment of the present invention;
FIG. 2 is a bottom view of the sliding button shown in FIG. 1;
FIG. 3 is an exploded perspective view of the double-sided sliding button
shown in FIG. 1 and a corresponding supporting clamp;
FIG. 4 is an perspective view of the resulting assembly of the sliding button
and the clamp shown in FIG. 3.
FIG. 5 is a cross-section view taken along line V-V in FIG. 4.
FIG. 6 is a schematic top cross-sectional view of the sliding button mounted in
its supporting clamp, showing the forces involved.
FIG. 7 is a schematic side cross-sectional view similar to that of FIG. 6.
FIG. 8 is a schematic side view showing two opposite ramps and a double-
sided sliding button.
FIG. 9 is a view similar to FIG. 6, showing another position for the sliding
button.
Throughout the figures, analogous components are identified by the same
reference numerals. Some parts which are not referred to correspond to the same
components shown in preceding figures.
The following is a list of reference numerals, along with the names of the
corresponding components, which are used in the description and in the
accompanying figures.
10 Double-sided sliding button
20 Half (of the sliding button 10)
22 Front side (of each half 20)
24 Rear side (of each half 20)
25 Bottom side (of each half 20)
26 Contact surface (of each half 20)
28 Flange (of each half 20)
30 Bridge member
32 Sleeve portion (of the bridge member 30)
100 Clamp
110 Central section (of the clamp 100)
112 Flange (of the clamp 100)
114 Slot (of the clamp 100)
116 Threaded bore (in the central section 110)
120 Side sections (of the clamp 100)
130 Radial slots (of the clamp 100)
140 Screw
200 Ramps
M Curved medial axis
FIGS. 1 to 9 show a double-sided sliding button (10) in accordance with a
preferred embodiment of the present invention. The double-sided sliding button
(10) is shown with the preferred embodiment for a corresponding clamp (100)
used to attach the sliding button (10). These parts are to be installed in a
reversible driven pulley. Like the other components of a driven pulley, the sliding
button (10) and the clamp (100) are configured and disposed to be symmetrical
with reference to the rotation axis of the driven pulley. This also allows the driven
pulley to remain balanced when rotating.
The sliding button (10) is constructed with reference to a curved medial axis (M).
The center of the curved medial axis (M) is preferably the rotation axis of the
driven pulley. The driven pulley has one sheave which is able to slide and rotate
with reference to the other sheave. The sliding buttons (10) are then mounted on
one of these sheaves. Corresponding ramps (200) are mounted on the other
sheave. The ramps (200) are curved as well.
As can be seen, the sliding button (10) comprises two spaced-apart sliding button
halves (20). Each half (20) is in fact a sliding button corresponding to one of the
ramps (200). Both halves (20) are not necessarily identical since they are used in
different contexts. For instance, when the vehicle travels in reverse, the response
of the driven pulley do not need to be the same compared to when the vehicle
travels in a forward direction. The shape of the ramps (200) of each set also
changes as well.
Each half (20) has a front side (22), a rear side (24) and a bottom side (25). The
front side (22) is provided with a contact surface (26), which contact surface (26) is
shaped in accordance with the design requirement and to maintain a good contact
with the corresponding ramp (200). Examples of ramps (200) are shown in
FIGS. 8 and 9. The contact surface (26) defines a three-dimensional curve, or
helix, which is matched by an opposite curve on the surface of a corresponding
ramp (200). As best shown in FIG. 2, both contact surfaces (26) of the sliding
button (10) are mutually opposite and both front sides (22) intersect the curved
medial axis (M).
A bridge member (30) is used to maintain together the two sliding button halves
(20). This bridge member (30) is rigidly connected to the rear side (24) of the two
sliding button halves (20). The bridge member (30) is preferably aligned with the
curved medial axis (M), although it could also be located elsewhere, for instance
closer to an edge of the sliding button halves (20). It also preferably comprises a
sleeve portion (32) having a center axis extending substantially parallel to the rear
side (24) of the sliding button halves (20).
Preferably, each half (20) further comprises a flange (28) projecting from the
bottom side (25). These flanges (28) allow to tightly secure the sliding button (10)
in place. Each flange (28) is adjacent to the rear side (24) of the corresponding
half (20) and extend parallel thereto. The purpose of these flanges (28) will be
explained hereafter.
The clamp (100) used to hold the sliding button (10) is preferably T- shaped, as
shown in FIG. 3. Other configurations can be used as well. The clamp (100) is
generally curved and aligned with the curved medial axis (M). It comprises a
central section (110) and two opposite side sections (120). The central section
(110) and the side sections (120) are preferably separated by radial slots (130).
The central section (110) of each clamp (100) comprises opposite and spaced-
apart flanges (112). The two flanges (112) define between them a slot (114)
between which the bridge member (30) of the sliding button (10) will be inserted.
Furthermore, as shown in FIG. 5, a threaded bore (116) is provided in the central
section (110) in order to receive the free end of a screw (140) designed to secure
the sliding button (10) in place. It should be noted that the screw (140) can be
replaced by any other equivalent connector.
The design of the parts is such that the sliding button (10) should fit snugly and
tightly into the clamp (100), as shown in FIG. 4. This insures that the forces are
properly balanced and that the sliding button (10) remains in place. The projecting
flanges (28) of the sliding button (10) then extend into the radial slots (130) of the
clamp (100) with an interfering engagement. The flanges (28) preferably comprise
a plurality of bosses which allow to facilitate the insertion of the flanges (28) in
their respective radial slot (130).
FIGS. 6 and 7 show the forces involved when the sliding button which is installed
in the clamp (100). As can be seen, the sides of the central section (110) are
preferably slightly inclined and define between them an angle 9i. Since the rear
sides (24) of the halves (20) are parallel, the insertion of the sliding button (10) into
the clamp (100) induces pressing forces on the sides of the central section (110).
These forces are referred to as F-, and F2 in FIG. 6. These forces are also shown
in FIG. 7. It should be noted that the design should not be such that the sliding
button (10) will have a tendency to come out of the clamp (100) by itself.
Nevertheless, the screw (140) (shown in FIG. 7) produces a force F3 which
maintains the sliding button (10) in place.
As can also be seen in FIG. 6, the two flanges (28), located in the radial slots
(130), are designed to apply two opposite forces, referred to as F4 and F5. These
forces allow to maintain the bottom side (25) of each half (20) against the side
sections (120). Forces F6 and F7 are then applied by the bottom sides (25). All
this prevents the half (20) to be lifted from the corresponding side section (120)
when the contact surface (26) of the opposite half (20) is engaged against a
corresponding ramp (200).
As can be seen from FIG. 7, the sides of the flanges (112) of the central section
(110) are separated by an angle 92 which is slightly greater than the distance
between the two halves (20). This creates forces Fs and Fq which press the inner
side of the sliding button (10) against the structure to which the clamp (100) is
attached. Such structure can also be seen in FIG. 5. This also promotes stability
of the sliding button (10) when it is in use. Among other things, it prevents the
inner side of each half (20) from detaching from the adjacent wall under the effect
of the elastic forces F10 and F-h created by the slight stretching of the bridge (30).
FIGS. 8 and 9 schematically show how the sliding button (10) can move while it is
in use. During normal use, the contact surface (26) of one sliding button half (20)
is in engagement with the corresponding ramp (200). When the direction of the
torque changes to the point that this can no longer be compensated by the spring
of the driven pulley, the sliding button (10) changes position and is moved towards
the opposite ramp (200). This transition period is usually very short. If desired, a
damping element (not shown) can be provided between the sliding button (10) and
the clamp (100) in order to decrease the shocks caused when the sliding button
(10) hits the opposite ramp (200).
As can be appreciated, the double-sided sliding button (10) has many advantages
compared to single sliding buttons for reversible driven pulleys. Among other
things, the double-sided sliding button (10) can be easily installed and secured in a
clamp attached to a part of the driven pulley The number of individual sliding
buttons is also reduced by 50%.
WE CLAIM :
1. A double-sided sliding button (10) for use in a reversible driven pulley, the sliding button (10)
comprising :
two spaced-apart sliding button halves (20) configured and disposed with reference to a
curved medial axis (M), each half (20) having a front side (22), provided with a contact surface (26),
a rear side (24) and a bottom side (25), both contact surfaces (26) being mutually opposite and both
front sides (22) intersecting the curved medial axis (M); and
a bridge member (30) rigidly connected to the rear side (24) of the two halves (20).
2. The double-sided sliding button (10) as claimed in claim 1, wherein the bridge member (30)
is aligned with the medial axis (M).
3. The double-sided sliding button (10) as claimed in claim 2, wherein the bridge member (30)
comprises a sleeve portion (32) having a center axis extending between to the rear side (24) of the
halves (20).
4. The double-sided sliding button (10) as claimed in any one of claims 1 to 3, wherein each half
(20) has a flange (28) projecting from the bottom side (25) and extending parallel to the rear side (24)
of the half (20).
5. The double-sided sliding button (10) as claimed in claim 4, wherein the rear side (24) is flat.
6. The double-sided sliding button (10) as claimed in any one of claims 1 to 5, wherein the
halves (20) and the bridge member (30) are integrally connected in a one-piece molded plastic item.
The double-sided sliding button (10) comprises two spaced-apart sliding button halves (20).
Each half (20) has a front side (22), provided with a contact surface (26), and a rear side (24). Both
contact surfaces (26) are mutually opposite and both front sides (22) of each half (20) intersect the
curved medial axis (M). A bridge member (30) connects the two halves (20) together. With this
configuration, each sliding button (10) can be easily installed and secured in a clamp (100) attached
to a part of a reversible driven pulley of a continuously variable transmission (CVT). Each double-
sided sliding button (10) is capable of working in both directions, thereby reducing the number of
individual sliding buttons to be installed by 50%.

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Patent Number

225426

Indian Patent Application Number

01969/KOLNP/2005

PG Journal Number

46/2008

Publication Date

14-Nov-2008

Grant Date

12-Nov-2008

Date of Filing

05-Oct-2005

Name of Patentee

CVTECH R & D INC.

Applicant Address

300, RUE LABONTE, DRUMMONDVILLE, QUEBEC J2C 6X9

Inventors:

#	Inventor's Name	Inventor's Address
1	LABBE, JOCELYN	203, SAVIGNAC, ST-GERMAIN-DE-GRANTHAM, QUEBEC, J0C 1K0

PCT International Classification Number

F16H 61/00, 55/56

PCT International Application Number

PCT/CA2004/000392

PCT International Filing date

2004-03-16

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10/390,097	2003-03-17	U.S.A.
2	2,422,450	2003-03-17	U.S.A.