JP2014141980A - Torque cam device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque cam device capable of preventing or suppressing the occurrence of shock during selecting positive or negative torque.SOLUTION: A torque cam device 14 having a pulley 8 consisting of a fixed sheave 8a and a movable sheave 8b generates thrust to press the movable sheave 8b depending on torque to be transmitted. It includes a cam member 15 formed with a first cam face 29 for converting positive toque into thrust and a second cam face 30 for converting negative torque into thrust, a first cam follower member 24 to be moved along the first cam face 29, a second cam follower member 25 to be moved along the second cam face 30, and elastic members 22, 23 for generating at least one of elastic force to press the first cam follower member 24 against the first cam face 29 and elastic force to press the second cam follower member 25 against the second cam face 30.

Description

  The present invention includes a fixed sheave in which a pulley around which a belt is wound is fixed to a rotation shaft of the pulley, and a movable sheave that is movable in the axial direction of the rotation shaft so as to approach and separate from the fixed sheave. The present invention also relates to a torque cam device that generates a thrust force that pushes the movable sheave toward the fixed sheave according to the torque to be transmitted.

  An example of this type of device is described in Patent Document 1. The torque cam device described in Patent Document 1 is provided on a driven pulley of a belt type continuously variable transmission, generates a thrust according to a torque to be transmitted in the axial direction of the driven pulley, and the belt is driven by the thrust. It is designed to pinch. The torque cam device includes a first cam device that generates thrust in the axial direction when driven, and a second cam device that generates thrust in the axial direction when driven. Each cam device has an input side cam member and an output side cam member, and a cam surface is formed on each cam member. A cam roller is disposed between the cam surface of the input cam member and the cam surface of the output cam member. Also, a buffer means for applying an elastic force to the cam members formed on the cam members of the first cam device and the cam surfaces formed on the cam members of the second cam device so as to approach each other. Is provided. And at the time of a drive and a to-be-driven, it is comprised so that the movable sheave in a driven pulley may be pressed toward a fixed sheave with the thrust generated with each cam apparatus.

  Patent Document 2 is configured to generate a thrust force that presses a movable sheave in a driven pulley of a belt type continuously variable transmission toward a fixed sheave by an elastic force of a coil spring, a torque cam device, and hydraulic pressure. A belt type continuously variable transmission is described. The torque cam device includes an uneven first engagement portion formed in an annular shape on the back side of the movable sheave, a second engagement portion having a shape facing the first engagement portion, a first engagement portion, and a second engagement portion. And a spherical member disposed between the first engaging portion and the second engaging portion. The shock-absorbing mechanism shocks when the operating state of the torque cam device is switched, and in particular, the operating state of the torque cam device is switched from the non-operating state to the operating state so that there is a gap between the first engaging portion and the second engaging portion. It is configured to reduce a shock in the case of sudden narrowing.

  Further, Patent Document 3 describes a driving force control device configured to distribute a driving torque transmitted from a transmission output shaft to two output shafts via a driving force distribution clutch. In addition, a torque cam device is provided between the input side member connected to the transmission output shaft and the pressure plate in the driving force distribution clutch. When the torque cam device is operated, the pressure plate is pressed and driven. The force distribution clutch is engaged, and the drive torque described above is distributed to the two output shafts via the drive force distribution clutch. A preload spring is provided between the input side member and the pressure plate, and the pressure plate is pressed by the elastic force to set the driving force distribution clutch in a half-engaged state.

JP 2006-291999 A JP 2005-172050 A JP 2009-179166 A

  In the torque cam device described in Patent Document 1 and Patent Document 2, the number of parts increases by the provision of the cam roller between the cam members arranged to face each other, which may increase the material cost and the manufacturing cost. Therefore, a torque cam device in which no cam roller is arranged between cam members as described in Patent Document 3 is used as a pressing mechanism in the driven pulley of the belt-type continuously variable transmission described in Patent Document 1 or Patent Document 2. It is possible.

  The torque transmitted by each of the torque cam devices described above includes a torque in the forward rotation direction or the forward rotation direction in the rotation direction of the rotating shaft that transmits the torque, and a torque in the reverse rotation direction. Here, the former is called positive torque and the latter is called negative torque. The switching between the positive and negative torques occurs, for example, when a forward / reverse switching mechanism is operated, that is, when the vehicle is switched from forward travel to reverse travel. When the torque transmitted by the torque cam device is switched from positive torque to negative torque, the cam surfaces engaged by the torque cam device are also switched in accordance with the switching. In the torque cam device described in Patent Document 3, since the elastic force of the preload spring acts to separate the input side member and the pressure plate, their widths are increased. Accordingly, the clearance between the other cam surfaces in the released state is relatively large, and a shock may occur when the positive and negative torques described above are switched and the other cam surfaces engage with each other.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a torque cam device that can prevent or suppress the occurrence of shock when switching between positive and negative torques.

  In order to achieve the above object, the invention according to claim 1 is characterized in that a pulley around which a belt is wound is fixed to a fixed sheave fixed to a rotating shaft of the pulley, and the pulley approaches and separates from the fixed sheave. A torque sheave that generates a thrust force that presses the movable sheave toward the fixed sheave according to the torque that is transmitted. A cam member formed with a first cam surface that converts to thrust and a second cam surface that converts torque in the reverse rotation direction to the thrust, and moves along the first cam surface and the first cam surface The first cam follower member that receives the thrust by the contact load with the second cam surface moves along the second cam surface and receives the thrust by the contact load with the second cam surface. A second cam follower member, and an elastic member that generates at least one of an elastic force that presses the first cam follower member against the first cam surface and an elastic force that presses the second cam follower member against the second cam surface Are provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the cam member is disposed adjacent to the movable sheave and on the same axis as the movable sheave, and the first cam surface and the second cam surface are The first cam follower member and the first cam follower member are formed to be continuous with each other so as to form a V-shaped concave portion that is inclined with respect to a plane perpendicular to the rotation center axis of the cam member and opens toward the movable sheave. The second cam follower member is disposed inside the V-shaped recess and is connected to the movable sheave so as to move in the axial direction together with the movable sheave. The first cam follower member and the second cam follower The first cam follower member and the second cam follower member approach each other as the member moves along the movable sheave along the inside of the V-shaped recess in the axial direction. And a guide member that guides the first cam follower member and the second cam follower member so as to move linearly within a plane perpendicular to the rotation center axis of the cam member when separating the first cam follower member and the second cam follower member. The torque cam device.

  According to the first aspect of the present invention, each cam follower member comes into contact with the corresponding cam surface by the elastic force of the elastic member, even when the pulley or torque cam device transmits torque in any rotational direction. Therefore, for example, a shock at the time of switching from a state in which thrust is generated between the first cam follower member and the first cam surface to a state in which thrust is generated between the second cam follower member and the second cam surface. Can be prevented or suppressed. In addition, since each cam follower member is pressed against each cam surface by the elastic force of the elastic member, torque can be transmitted instantaneously even if the location where the thrust is generated is changed. Therefore, torque transmission efficiency can be improved.

  According to the invention of claim 2, in addition to the effect similar to the effect of the invention of claim 1, the wrapping radius of the belt in the pulley is changed, and the distance between the cam member and each cam follower member is accordingly changed. When it changes, it can prevent or suppress that each cam follower member bends in the direction of a rotation center axis. Thus, since the followability of each cam follower member with respect to the movement of the movable sheave can be improved, the torque cam device can be operated as expected to obtain the desired thrust.

It is a figure which shows typically an example of the torque cam apparatus which concerns on this invention. It is a figure which shows typically the other example of the torque cam apparatus which concerns on this invention. It is a figure which shows typically the other example of the torque cam apparatus which concerns on this invention. It is sectional drawing which shows typically the driven pulley in a belt-type continuously variable transmission. It is a figure which shows typically an example of the vehicle which can be made into object by this invention.

  Next, the present invention will be specifically described. FIG. 5 is a diagram schematically showing an example of a vehicle that can be a subject of the present invention. The vehicle shown here has a belt-type continuously variable transmission 5 attached to the output side of the engine 1 via a torque converter 3 with a lock-up clutch 2 and a forward / reverse switching mechanism 4, and the belt-type continuously variable transmission. 5 is configured to transmit torque to the left and right drive wheels 6 via a final reduction gear (not shown). The belt-type continuously variable transmission 5 is a so-called dry belt-type continuously variable transmission that does not lubricate the contact portion between the belt and the pulley. The engine 1 is basically an internal combustion engine that burns fuel and outputs power, and a gasoline engine or a diesel engine is a typical example. The torque converter 3 has the same configuration as that conventionally known, and the lockup clutch 2 is configured to mechanically directly connect the input side member and the output side member of the torque converter 3. The configuration is the same as that conventionally known. The forward / reverse switching mechanism 4 has a configuration similar to that conventionally known, and selectively switches the rotational direction of the torque transmitted from the engine 1 to the drive wheels 6 between the forward direction and the reverse direction of the vehicle. It is configured.

  The belt type continuously variable transmission 5 includes a drive pulley 7 and a driven pulley 8, and a pulley shaft 9 of the drive pulley 7 is an output shaft of the engine 1 via the torque converter 3 and the forward / reverse switching mechanism 4 described above. It is connected to the crankshaft 10 so that power can be transmitted. The pulley shaft 11 of the driven pulley 8 is connected to the left and right drive wheels 6 through a final reduction gear so that power can be transmitted. The pulleys 7 and 8 are both provided with fixed sheaves 7a and 8a integral with the pulley shafts 9 and 11 and are movable back and forth on the pulley shafts 9 and 11 so as to approach and separate from the fixed sheaves 7a and 8a. Movable sheaves 7b and 8b. Between these fixed sheaves 7a and 8a and the movable sheaves 7b and 8b, V-groove belt winding grooves are formed. A belt 12 is wound around the belt winding groove. On the back side of the movable sheaves 7b and 8b, thrust mechanisms 7c and 8c for pressing the movable sheaves 7b and 8b toward the fixed sheaves 7a and 8a are provided, respectively.

  Although not shown, the thrust mechanism 7c in the drive pulley 7 uses, for example, a motor as a power source, and converts the torque of the motor into thrust in a direction parallel to the rotation axis of the drive pulley 7, thereby converting the movable sheave 7b into the fixed sheave 7a. It is made to approach and separate from the fixed sheave 7a. On the other hand, the thrust mechanism 8c in the driven pulley 8 is constituted by, for example, a torque cam device 14 and pressing springs 17 and 18, which will be described later, and presses the movable sheave 8b toward the fixed sheave 8a by the thrust generated by these. Yes.

  FIG. 4 is a cross-sectional view schematically showing the driven pulley 8 in the belt type continuously variable transmission 5. The movable sheave 8 b is slidable in the axial direction of the pulley shaft 11, and is It is attached so that it can rotate. A cylindrical portion 13 is integrally provided on the back side of the movable sheave 8b. The cylindrical portion 13 is a member provided with a part of the torque cam device 14 according to the present invention. A cam member 15 is disposed so as to face the cylindrical portion 13, and the cam member 15 is fitted to the pulley shaft 11. ing. The cylindrical portion 13 and the cam member 15 are relatively rotatable. A bearing 16 is provided on the opposite side of the cam member 15 from the movable sheave 8 b, and the movement of the cam member 15 in the right direction in FIG. 4 in the axial direction of the pulley shaft 11 is regulated by the bearing 16. The torque cam device 14 will be described later.

  Moreover, in the example shown here, the two press springs 17 and 18 are provided in the back side of the movable sheave 8b, and these press springs 17 and 18 are provided between the shims 19 and 20. The elastic force of each of the pressing springs 17 and 18 acts on the movable sheave 8b so as to press the movable sheave 8b toward the fixed sheave 8a. The shims 19 and 20 are formed in an annular shape, and are provided between the movable sheave 8 b and the cam member 15 so as to be movable in the axial direction of the pulley shaft 11. The shims 19 and 20 may be rotatable relative to the movable sheave 8b and the cam member 15.

  FIG. 1 is a view for explaining an example of a torque cam device according to the present invention, and a protruding portion 21 is provided at an end portion of a cylindrical portion 13. The central axis of the protrusion 21 is disposed on the same axis as the pulley shaft 11. A first cam follower member 24 and a second cam follower member 25 are attached to the protruding portion 21 via coil springs 22 and 23. Specifically, one end portions of the coil springs 22 and 23 are connected to the protruding portion 21, and the other end portions are connected to the first cam follower member 24 and the second cam follower member 25, respectively. In addition, you may comprise so that the protrusion part 21 may be connected to the center part of one coil spring, and the 1st cam follower member 24 and the 2nd cam follower member 25 may be connected to both ends, respectively. The cam follower members 24 and 25 are formed with inclined surfaces 24a and 25a that are opposed to a cam surface, which will be described later, and are parallel to the cam surfaces, and friction materials 26 and 27 are formed on the inclined surfaces 24a and 25a. Each is provided. Each friction material 26, 27 has a predetermined coefficient of friction. Each friction material 26, 27 also functions as a member that cushions shock caused by contact between a cam surface, which will be described later, and each cam follower member 24, 25.

  A plurality of V-shaped concave portions 28 that are open toward the movable sheave 8b side are formed in the circumferential direction in the end portion of the cam member 15 on the movable sheave 8b side. A first cam surface 29 is formed on one surface of each recess 28, and a second cam surface 30 is formed on the other surface. Each of the cam surfaces 29 and 30 is formed to be inclined with respect to a plane perpendicular to the central axis of the cam member 15. The first cam surface 29 is formed in parallel with the above-described inclined surface 24a, and the second cam surface 30 is formed in parallel with the above-described inclined surface 25a. The contact load at which the cam follower members 24 and 25 start to slide along the cam surfaces 29 and 30 increases as the inclination angle of the cam surfaces 29 and 30, that is, the cam angle increases. When the cam angle increases, the positive and negative torques at which the torque cam device 14 operates are increased. As shown in FIG. 1, the first cam follower member 24 is in contact with the first cam surface 29 via the friction material 26, and the second cam follower member 25 is connected to the second cam surface 30 with the friction material. 27 is in contact.

  Next, the operation of the torque cam device 14 configured as described above will be described. In the following description, the rotation direction of the pulley shaft 11 when the vehicle equipped with the belt type continuously variable transmission 5 configured as described above travels forward is referred to as a forward rotation direction or a forward rotation direction, and the opposite rotation direction is reversed. Called the direction of rotation. The torque in the forward rotation direction is referred to as positive torque, and the torque in the reverse rotation direction is referred to as negative torque.

  When traveling forward, when torque from the engine 1 is transmitted to the torque cam device 14, torque is transmitted between the first cam follower member 24 and the first cam surface 29. That is, when a load is generated between the first cam follower member 24 and the first cam surface 29, a thrust is generated between the members 24 and 29. When the positive torque increases and slip occurs between the members 24 and 29, for example, the first cam follower member 24 moves upward along the first cam surface 29 in FIG. As a result, thrust is generated in the axial direction, and the movable sheave 8b is pressed toward the fixed sheave 8a by the thrust and belt clamping pressure is generated. Note that the above-mentioned “case where the positive torque input to the torque cam device 14 increases” is an example where the positive torque transmitted by the belt-type continuously variable transmission 5 increases. The torque cam device 14 having the above-described configuration operates even when a so-called reverse input torque or negative torque from the drive wheel 6 side is larger than the positive torque, and generates the thrust.

  When the forward / reverse switching mechanism 4 is operated to switch from forward travel to reverse travel, the state in which torque is transmitted between the first cam follower member 24 and the first cam surface 29 in the torque cam device 14 is released. The torque is transmitted between the second cam follower member 25 and the second cam surface 30. In this case, since the second cam follower member 25 is always pressed against the second cam surface 30 by the coil spring 23, even if the torque transmitted by the torque cam device 14 is switched from the positive torque to the negative torque, It is possible to prevent the occurrence of shocks and abnormal noise. Similarly, even when the forward / reverse switching mechanism 4 is operated to switch from reverse travel to forward travel, the first cam follower member 24 is always pressed against the first cam surface 29 by the coil spring 22. Similarly to the above, it is possible to prevent the occurrence of shock and abnormal noise between them. As described above, the cam follower members 24 and 25 are pressed against the cam surfaces 29 and 30 by the coil springs 22 and 23. Therefore, regardless of the speed ratio of the belt-type continuously variable transmission 5, When the transmission torque in the torque cam device 14 is switched between positive and negative, the above-described shock and noise can be prevented.

  FIG. 2 is a view for explaining another example of the torque cam device according to the present invention. In the example shown here, the first cam follower member 24 is moved by the coil spring 22 in the torque cam device 14 to the first cam surface. This is an example in which the second cam follower member 25 is directly attached to the protruding portion 21 while being always in contact with the protrusion 29. The operation of the torque cam device having such a configuration will be described. When the vehicle starts traveling forward, the first cam follower member 24 and the first cam surface 29 are in contact with each other by the coil spring 22.

  When the positive torque transmitted by the torque cam device 14 increases and slip occurs between the first cam follower member 24 and the first cam surface 29, the first cam follower member 24 moves along the first cam surface 29 in FIG. 2. The thrust is increased by moving upward at, thereby increasing the belt clamping pressure. On the other hand, when reverse input torque or negative torque is input to the torque cam device 14, the state in which torque is transmitted between the first cam follower member 24 and the first cam surface 29 is released, and the second The cam follower member 25 and the second cam surface 30 come into contact with each other to transmit torque. In this case, since the friction material 27 attached to the second cam follower member 25 functions as a cushioning material, the occurrence of shock or noise due to the contact between the second cam follower member 25 and the second cam surface 30 is prevented. It can be prevented or suppressed. The same applies to the case where the forward / reverse switching mechanism 4 is operated to switch from forward travel to reverse travel. Further, when the forward / reverse switching mechanism 4 is operated to switch from reverse travel to forward travel, the first cam follower member 24 is always in contact with the first cam surface 29 by the coil spring 22 as described above. It is possible to prevent the above-described shock and noise.

  FIG. 3 is a view for explaining still another example of the torque cam device according to the present invention. In the example shown here, the movement of each cam follower member 24, 25 is guided by the guide member 31. This is an example. As an example, the guide member 31 is configured by a rail that can be expanded and contracted along a plane perpendicular to the central axis of the pulley shaft 11, and the central portion of the guide member 31 is connected to the protruding portion 21. Cam follower members 24 and 25 are movably attached to end portions of the guide member 31 in the left-right direction in FIG. The operation of the torque cam device having such a configuration will be described. Since the cam follower members 24 and 25 are in contact with the cam surfaces 29 and 30 by the coil springs 22 and 23, the transmission torque in the torque cam device 14 is switched between positive and negative. However, it is possible to prevent the torque cam device 14 from generating shocks and abnormal noise.

  Further, in the torque cam device 14 having the configuration shown in FIG. 3, the cam follower members 24 and 25 follow the guide member 31 in the left and right directions in FIG. 3 when the speed ratio of the belt type continuously variable transmission 5 changes. It moves in the direction and moves up and down in FIG. 3 together with the guide member 31. Therefore, the follower of the cam follower members 24 and 25 with respect to the movable sheave 8b can be improved by preventing or suppressing the bending of the coil springs 22 and 23 due to the movement of the movable sheave 8b in the vertical direction in FIG. . In addition to this, since the guide member 31 expands and contracts, even if the movable sheave 8b moves in the vertical direction in FIG. Contact can be prevented or suppressed.

  More specifically, when a large gear ratio is set, the movable sheave 8b moves upward in FIG. 3 to narrow the width between the fixed sheave 8a and the movable sheave 8b. As the movable sheave 8 b moves, the cam follower members 24, 25 move upward along the cam surfaces 29, 30 in FIG. 3, and the coil springs 22, 23 extend along the guide member 31. The guide member 31 is extended by the elastic force of the coil springs 22 and 23.

  On the other hand, when a small gear ratio is set, the movable sheave 8b moves downward in FIG. 3 to increase the width between the fixed sheave 8a and the movable sheave 8b. As the movable sheave 8 b moves, the cam follower members 24, 25 move downward along the cam surfaces 29, 30 in FIG. 3, and the coil springs 22, 23 contract along the guide member 31. Further, the guide member 31 also contracts. In this way, the followability of the cam follower members 24 and 25 with respect to the movement of the movable sheave 8b can be improved, so that the torque cam device 14 can be operated as expected and the cam can be operated regardless of the speed ratio. It is possible to prevent or suppress the occurrence of shock and abnormal noise due to contact between the follower members 24 and 25 and the cam surfaces 29 and 30.

  8 ... driven pulley, 8a ... fixed sheave, 8b ... movable sheave, 12 ... belt, 14 ... torque cam device, 22, 23 ... coil spring, 24 ... first cam follower member, 25 ... second cam follower member, 29 ... first 1 cam surface, 30 ... 2nd cam surface.

Claims (2)

A pulley around which a belt is wound is constituted by a fixed sheave fixed to the rotation shaft of the pulley and a movable sheave movable in the axial direction of the rotation shaft of the pulley so as to approach and separate from the fixed sheave. In a torque cam device that generates a thrust for pressing the movable sheave toward the fixed sheave according to the torque to be transmitted,
A cam member formed with a first cam surface that converts torque in the forward rotation direction into the thrust and a second cam surface that converts torque in the reverse rotation direction into the thrust;
A first cam follower member that moves along the first cam surface and receives the thrust by a contact load with the first cam surface;
A second cam follower member that moves along the second cam surface and receives the thrust by a contact load with the second cam surface;
And an elastic member that generates at least one of an elastic force that presses the first cam follower member against the first cam surface and an elastic force that presses the second cam follower member against the second cam surface. Torque cam device. The cam member is disposed adjacent to the movable sheave and on the same axis as the movable sheave;
The first cam surface and the second cam surface are continuous with each other so as to be inclined with respect to a plane perpendicular to the rotation center axis of the cam member and to form a V-shaped recess that opens toward the movable sheave. Formed,
The first cam follower member and the second cam follower member are disposed inside the V-shaped recess and connected to the movable sheave so as to move in the axial direction together with the movable sheave.
As the first cam follower member and the second cam follower member move together with the movable sheave in the V-shaped recess in the axial direction, the first cam follower member and the second cam follower member And a guide member that guides the first cam follower member and the second cam follower member so as to move linearly within a plane perpendicular to the rotation center axis of the cam member when they approach and separate from each other. The torque cam device according to claim 1.

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