JP2018021587A - Continuously variable transmission for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce energy loss of an actuator for driving a movable sheave of a primary pulley, in a continuously variable transmission for a vehicle.SOLUTION: In a continuously variable transmission for a vehicle, a torque cam mechanism 30 is disposed so as to be rotatable relatively to a back side of a movable sheave 12 of a primary pulley 6 and two cams 40, 46 of the torque cam mechanism 30 is configured so that friction torque acting on the torque cam mechanism 30 from the primary pulley 6 when a vehicle travels forward acts in a direction of increasing the whole length of the torque cam mechanism 30.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a continuously variable transmission mounted on a vehicle.

  2. Description of the Related Art A belt-type continuously variable transmission is known in which an endless belt member such as a belt or a chain is wound between two pulleys to achieve power transmission and speed change between both pulleys.

  Patent Document 1 discloses a technique for moving a movable sheave using a slide cam as a transmission mechanism of a belt-type continuously variable transmission.

Japanese Patent Laid-Open No. 2006-1013

In a belt-type continuously variable transmission, while the vehicle is running, that is, when power is transmitted between the pulleys, the belt thrust between the two sheaves of the pulley (attempting to separate the sheaves). Therefore, even when the speed ratio is constant, it is necessary to apply a force against the thrust to the movable sheave, which contributes to an increase in energy loss.
Even in the technology disclosed in Patent Document 1, even when the operation of the slide cam is stopped (a state in which the speed ratio is constant), it is necessary to generate a force that opposes the belt thrust on the actuator, resulting in energy loss. Contributes to the increase.

  The present invention was devised to solve the above-described problems, and drives a movable sheave of the pulley in a continuously variable transmission configured to achieve power transmission and speed change between two pulleys. The purpose is to reduce energy loss due to the actuator.

  (1) In order to achieve the above object, a continuously variable transmission for a vehicle according to the present invention winds an endless belt-like member between a primary pulley connected to a drive source of a vehicle and a secondary pulley connected to a drive wheel. A continuously variable transmission for a vehicle that rotates to achieve power transmission and speed change between both pulleys, a first cam fixedly connected to a casing of the continuously variable transmission for the vehicle, and one end of the first cam And a second cam connected to the back surface of the movable sheave of the primary pulley via a thrust bearing so as to be relatively rotatable, and the first and second cams along the rotation direction of the pulley. A torque cam mechanism configured to change a total length along the rotation axis direction of the pulley by relative displacement of the pulley, and the torque from the primary pulley through the thrust bearing during forward travel of the vehicle Friction torque acting on the arm mechanism is characterized by being configured the first and second cam so as to act in a direction to increase the overall length of the torque cam mechanism.

(2) At least one of the first and second cams includes a cam surface formed by a slope along the rotation direction of the pulley, and the slope is along the rotation direction of the primary pulley during forward travel of the vehicle. It is preferable to be formed so as to approach the movable sheave back surface.
(3) The first and second cams are formed of two cylindrical members that are formed with annular cam surfaces that face each other and are externally fitted to the rotation shaft of the primary pulley so as to be relatively rotatable. Is preferred.
(4) It is preferable that the torque cam mechanism is a ball cam mechanism in which a plurality of balls are interposed between the two annular cam surfaces.

(5) Moreover, it is preferable that the electric actuator which rotationally drives the said 2nd cam along the rotation direction of the said primary pulley is arrange | positioned.
(6) Furthermore, it is preferable that the end of the first cam opposite to the second cam is connected to a side surface of an annular member fixed to the rotation shaft of the primary pulley via a thrust bearing.
(7) Furthermore, it is preferable that the first cam is fixedly connected to the casing on the outer peripheral surface side.

  According to the present invention, the torque cam mechanism whose total length changes according to the relative displacement along the rotational direction of the primary pulley is disposed on the back side of the primary pulley, and the primary pulley acts on the torque cam mechanism when the vehicle travels forward. Since the friction torque to be applied acts in a direction that increases the overall length of the torque cam mechanism, a force that counteracts the belt thrust can be constantly applied to the primary pulley by the action of the torque cam mechanism during forward travel. Therefore, energy loss in the actuator for driving the movable sheave can be reduced.

1 is a configuration diagram schematically illustrating a configuration of a continuously variable transmission for a vehicle according to an embodiment of the present invention. It is a fragmentary sectional view showing the structure of the primary pulley of the continuously variable transmission for vehicles concerning one embodiment of the present invention. It is a block diagram which shows typically the structure of the torque cam applied to one Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the following embodiments can be implemented with various modifications without departing from the spirit thereof, and can be selected or combined as appropriate.

  FIG. 1 is a configuration diagram schematically showing a continuously variable transmission for a vehicle according to the present embodiment. As shown in FIG. 1, a drive source 2 composed of an internal combustion engine, an electric motor, etc. A rotary shaft 10 coupled to the fixed sheave 8 of the primary pulley 6 is connected via a forward / reverse switching mechanism 4 composed of a planetary gear mechanism or the like. A movable sheave 12 having a sheave surface that forms a V-shaped groove of a pulley facing the sheave surface of the fixed sheave 8 is arranged on the rotary shaft 10 so as to be slidable in the axial direction and not relatively rotatable. Yes.

  A drive wheel (not shown) is connected to the drive shaft 18 coupled to the fixed sheave 16 of the secondary pulley 14 via a differential mechanism or the like, and the drive shaft 18 faces the sheave surface of the fixed sheave 16. A movable sheave 20 having a sheave surface that forms a V-shaped groove of the pulley is disposed so as to be slidable in the axial direction and not relatively rotatable.

Further, between the sheaves 16 and 20 of the secondary pulley 14, a spring 22 and a cam mechanism 24 that apply a biasing force in the direction of narrowing the V-shaped groove are interposed.
A belt (endless belt-like member) 26 is wound between the pulleys 6 and 14.

  FIG. 1 shows a state where the gear ratio is on the low side and the state on the high side for the primary pulley 6, the secondary pulley 14, and the belt 26. A low-side state is shown in each outer half of the primary pulley 6 and the secondary pulley 14, and a high-side state is shown in each inner half. Regarding the belt 26, the low-side state is indicated by a solid line, and the high-side state is indicated by a broken line. However, the high state indicated by the broken line only indicates the positional relationship between the pulley and the belt in the radial direction, and the actual belt position does not appear in the inner half of the pulley.

  A torque cam mechanism 30, which will be described later, is disposed on the back side (surface opposite to the sheave surface) 13 of the movable sheave 12 of the primary pulley 6 via a thrust bearing 28.

  As shown in detail in FIG. 2, the torque cam mechanism 30 rotates relative to the inner peripheral surface of an annular support member 36 fixed to a casing 32 (not shown in FIG. 1) with a bolt 34 via a spline 38. A first cam 40 that is impossiblely connected and fixed, and a second cam surface 44 opposite to the first cam surface 42 formed on the first cam 40 are formed at one end (left side in the figure), and the other end (see FIG. The middle right side is provided with a second cam 46 connected to the back surface 13 of the movable pulley 12 via the thrust bearing 28. A plurality of balls 48 are interposed between the cam surfaces 42 and 44.

  The first and second cams 40, 46 are arranged on the outer peripheral side of the rotary shaft 10 and further on the outer peripheral side of the cylindrical shaft 12 a for supporting the movable sheave 12 on the rotary shaft 10. , 12) and a substantially cylindrical member that is externally fitted so as to be relatively rotatable.

  The first and second cam surfaces 42 and 44 are formed on the end surfaces of the cylindrical cams 40 and 46 facing each other, and the shape thereof is on the axis SC of the rotary shaft 10 as shown in FIG. The slopes (that is, the first and second cam surfaces 42 and 44) are movable along the rotational direction of the primary pulley 6 when the vehicle travels forward as indicated by an arrow A in FIG. It is formed with an inclination so as to approach the back surface 13 of the pulley 12.

  As shown in FIG. 1, the inner periphery of an annular drive ring 52 is connected to the outer periphery of the second cam 46 via a ball spline 50 so as not to be rotatable relative to the axial direction. The drive ring 52 is driven to rotate about the axis SC of the rotary shaft 10 by an electric actuator 54 such as a motor.

  Further, the end portion of the first cam 40 opposite to the first cam surface 42 (that is, the end portion opposite to the second cam 46, the left end in the figure) is interposed via a thrust bearing 60. The fixed nut 62 screwed to the rotary shaft 10 is connected to the side surface, and the fixed nut 62 prevents movement to the left in the axial direction.

  Accordingly, when the drive ring 52 is rotated by the electric actuator 54, the second cam 46 rotates with respect to the first cam 40, and the total length of the torque cam mechanism 30 changes due to the relative movement of the first and second cam surfaces 42 and 44. . If the total length of the torque cam mechanism 30 increases, the movable sheave 12 approaches the fixed sheave 8 and the gear ratio changes to HIGH. If the total length of the torque cam mechanism 30 decreases, the movable sheave 12 moves away from the fixed sheave 8. The gear ratio changes to the LOW side. Further, if the entire length of the torque cam mechanism 30 is kept constant, the transmission ratio is kept constant.

  Note that both ends of the rotary shaft 10 are supported by the casing 32 via bearings 64 and 66, respectively.

  Further, a flange portion 66 projecting inward is integrally formed at the end portion of the annular support member 36 on the casing 32 side, and the flange portion 66 functions as a retainer of the bearing 64.

  Since the continuously variable transmission for a vehicle according to an embodiment of the present invention is configured as described above, the following operations and effects can be obtained.

  When the second cam 46 is forcibly rotated around the rotating shaft 10 via the drive ring 52 by the electric actuator 54 during the forward traveling of the vehicle, the torque cam is caused by the action of the first and second cam surfaces 42 and 44. The total length along the axial direction of the mechanism 30 (the length from the left end of the first cam 40 to the right end of the second cam 46 in FIG. 2) changes, and accordingly, the movable sheave 12 moves on the rotary shaft 10 in the horizontal direction in the figure. In this way, a shift between the pulleys 6 and 14 is achieved. Further, if the entire length of the torque cam mechanism 30 is kept constant, the transmission ratio is kept constant.

  The thrust of the belt 26 acts on each pulley 6 and 14 in a direction in which the fixed sheaves 8 and 16 are separated from the movable sheaves 12 and 20 (that is, a direction in which the V-shaped groove is widened). In the primary pulley 6, the thrust of the belt 26 acts in a direction in which the sheaves 8 and 12 are separated from each other and the gear ratio is changed to the LOW side (that is, the total length of the torque cam mechanism 30 is reduced).

  Therefore, when the movable sheave 12 is moved in the direction in which the sheaves 8 and 12 of the primary pulley 6 are separated (that is, the direction in which the gear ratio changes to the LOW side), the thrust of the belt 26 is the same as the moving direction of the movable sheave 12. Since the electric actuator 54 acts in the direction, it is possible to achieve speed change with a relatively low load (energy consumption).

  On the other hand, when the movable sheave 12 is moved in the direction in which the sheaves 8 and 12 approach each other (that is, the direction in which the gear ratio changes to HIGH), the thrust of the belt 26 acts in the direction opposite to the moving direction of the movable sheave 12. Therefore, the electric actuator 54 is subjected to a load that is larger than the load that simply moves the movable sheave 12 alone.

According to the present embodiment, the frictional torque transmitted to the second cam 46 via the thrust bearing 28 acts in the direction indicated by the arrow B by the rotation of the movable sheave 12 in the direction indicated by the arrow A in FIG. The friction torque rotates (or attempts to rotate) the second cam 46 in a direction that increases the overall length of the torque cam mechanism 30, so that thrust is applied from the torque cam mechanism 30 to the movable sheave 12 in the direction indicated by arrow C. Is done.
Therefore, the addition of thrust by the torque cam mechanism 30 reduces the load on the electric actuator 54 and energy loss compared to the case where the torque cam mechanism 30 is not provided.

  Further, even when the gear ratio is kept constant while the vehicle is traveling forward, thrust is applied from the belt 26 in the direction in which the sheaves 8 and 12 are separated (the direction in which the movable sheave 12 is moved to the left in the figure). Therefore, in order to maintain the position of the movable sheave 12, the electric actuator 54 needs to generate a force that opposes the belt thrust.

Even in this case, according to the present embodiment, the friction torque transmitted to the second cam 46 via the thrust bearing 28 acts in the direction indicated by the arrow B by the rotation of the movable sheave 12 in the direction indicated by the arrow A. The friction torque rotates (or tries to rotate) the second cam 46 in a direction that increases the total length of the torque cam mechanism 30, so that a thrust is applied from the torque cam mechanism 30 to the movable sheave 12 in the direction indicated by arrow C. Added.
Therefore, the addition of thrust by the torque cam mechanism 30 reduces the load on the electric actuator 54 and energy loss compared to the case where the torque cam mechanism 30 is not provided.

  In particular, when a motor is used as the electric actuator 54, a current that generates torque in a rotation stopped state is added to the motor. However, according to the present embodiment, since the amount of current applied to the motor can be reduced, the heat generation amount can be reduced and the durability can be maintained.

  As described above, the continuously variable transmission for a vehicle according to an embodiment of the present invention can generate a force in a direction that opposes the belt thrust when the vehicle is traveling forward by the torque cam mechanism. Energy loss can be reduced by reducing the load required for the actuator for control.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and the above embodiment can be variously modified and applied without departing from the gist of the present invention. is there.

  For example, in the above embodiment, the torque cam mechanism is configured by forming the cam surfaces on the end surfaces facing each other of the two cylindrical members arranged in series, but one of the two cams is replaced with the cam surface of the other cam. You may comprise with the roller cam which contacts and rolls. However, even in this configuration, the cam surface of the other cam, like the cam surface of the above-described embodiment, needs to be configured with a slope that approaches the back of the movable sheave along the direction of pulley rotation during forward travel of the vehicle. It is.

  In the above embodiment, the torque cam mechanism is used as a part of the drive mechanism for driving the movable sheave. However, the torque cam mechanism may be configured separately from the drive mechanism of the movable sheave, or may be configured separately. Even if the structure is complicated, the same effects as those of the above embodiment can be obtained.

2 Driving source 6 Primary pulley 8 Fixed sheave 12 Movable sheave 14 Secondary pulley 30 Torque cam mechanism 40 First cam 46 Second cam

Claims (7)

In a continuously variable transmission for a vehicle, in which an endless belt-like member is wound between a primary pulley connected to a drive source of a vehicle and a secondary pulley connected to a drive wheel to achieve power transmission and speed change between the pulleys. ,
A first cam fixedly connected to a casing of the continuously variable transmission for the vehicle, one end facing the first cam, and the other end relatively rotated via a thrust bearing on the back of the movable sheave of the primary pulley A torque cam mechanism having a second cam connected to the pulley, and configured to change a total length along the rotation axis direction of the pulley by relative displacement of the first and second cams along the rotation direction of the pulley. With
The first and second cams are configured such that a friction torque that acts on the torque cam mechanism from the primary pulley through the thrust bearing during forward travel of the vehicle acts in a direction that increases the overall length of the torque cam mechanism. A continuously variable transmission for a vehicle. At least one of the first and second cams includes a cam surface formed by a slope along the rotation direction of the pulley, and the slope is a back surface of the movable sheave along the rotation direction of the primary pulley when the vehicle travels forward. The continuously variable transmission for a vehicle according to claim 1, wherein the continuously variable transmission is formed so as to approach the vehicle. The first and second cams are formed of two cylindrical members that are formed with annular cam surfaces facing each other and are externally fitted to the rotation shaft of the primary pulley so as to be relatively rotatable. The continuously variable transmission for a vehicle according to any one of claims 1 to 2. The continuously variable transmission for a vehicle according to claim 3, wherein the torque cam mechanism is a ball cam mechanism in which a plurality of balls are interposed between the two cam surfaces. The continuously variable transmission for a vehicle according to any one of claims 1 to 4, further comprising an electric actuator that rotationally drives the second cam along a rotation direction of the primary pulley. 2. The first cam is connected to a side surface of an annular member fixed to a rotation shaft of the primary pulley via a thrust bearing at an end opposite to the second cam. The continuously variable transmission for a vehicle according to any one of claims 5 to 6. The continuously variable transmission for a vehicle according to any one of claims 1 to 6, wherein the first cam is fixedly connected to the casing on an outer peripheral surface side thereof.

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