JP2005240928A - Rotary cam pressure regulating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotary cam pressure regulating device, in which, in a case where a pair of face cams are twisted depending on increase in load torque, rotary cams rotatably supported by one face cam are rotated so that rollers are rolled with an extremely stable where the rollers disposed in V-groove faces keep line contact with respect to V-groove faces of rotary cams and V-groove faces of the other face cam. <P>SOLUTION: A friction gearing type transmission device is a pressing force generating device for applying a pressing force to contact faces of rolling bodies depending on load torque acting at least one of an input shaft and an output shaft, by a pair of face cams which are disposed at positions facing each other and in which rolling elements are disposed. One face cam rotatably supports a plurality of rotary cams around an axial center of a face cam body. The rotary cam has a V-groove in which rollers as rolling elements are brought into contact along an axial direction. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a pressing force generating device that generates a pressing force on the contact surface of a rolling element, particularly in response to a change in load, in a transmission such as a variable speed reducer or a continuously variable transmission that transmits power by friction. The present invention relates to a structure for improving the load capacity of a pressure adjusting cam device capable of adjusting the pressing force.

  In a transmission using friction transmission, there are a method of applying a constant force with a spring as a pressing force generating device and a method of applying a pressing force proportional to a load with a cam. The former is the simplest method, but has a drawback that the transmission efficiency is low when the load is small, and the slip stall occurs when the load is excessive. The latter is used in many transmissions because it can maintain high efficiency regardless of changes in the load and there is no slip stall.

  A conventional cam system generally uses balls as rolling elements. However, the ball is in point contact with the V-groove surface of the cam, and although the occurrence of hysteresis is small when the load torque is increased or decreased, the contact surface is easily elastically deformed or plastically deformed by a large load torque. Since the desired function cannot be achieved by this deformation, there is a problem that the applied load torque is limited.

In order to solve such problems, a roller cam (Non-Patent Document 1) is employed, and a high-performance pressing force generator having a large load capacity and little hysteresis during operation has been reported. This has been studied to satisfy both the small hysteresis characteristic of the ball and the large load capacity characteristic of the roller. In this research, in order to absorb the speed difference between the outer peripheral side and the inner peripheral side, which can be said to be a defect of the roller, the roller was divided into a plurality of planes perpendicular to the rotation axis, and each divided roller was brought close to the contact state of the ball It is configured.
Transactions of the Japan Society of Mechanical Engineers (C), Vol. 56, No. 525 (1990-5) p1283-p1288 JP 2001-066566 A

  Although the roller cam disclosed in Non-Patent Document 1 can eliminate the speed difference from the V groove surface of the cam to some extent, this also means that a speed difference occurs between the rollers. For this reason, sliding friction is generated between the end faces of each roller, which causes an increase in hysteresis and a decrease in pressing force.

  Moreover, there exists patent document 1 as what solves this problem. This discloses a method of reducing sliding friction by reducing the contact area between the roller end faces. However, in this method, since the end surface of the roller is processed into a cone or an arc shape, the contact area between the V groove surface and the peripheral surface of the roller is reduced, and the original function as a roller that can increase the load capacity is impaired. Problems arise.

Moreover, in all of the above-described conventional techniques, the hysteresis is reduced by reducing the loss due to the speed difference between the roller and the V-groove surface, but no matter how finely divided, the roller has a width. Hysteresis does not go away. Also, as the load increases, the cams facing each other shift in phase, causing the rollers to make point contact with the V-groove surface, so that a plurality of rollers are arranged on the largest possible pitch circle and the lead angle of the V-groove is increased. There is a way to avoid this as much as possible by making it smaller. However, even with this method, the point contact between the roller and the V-groove surface cannot be eliminated, and when the load torque is reduced, the phase shift between the face cams does not return to the original due to the wedge effect, and the hysteresis It will also lead to an increase.

  Therefore, the present inventor has achieved the present invention as a result of intensive studies in view of the above problems, and the feature thereof is a friction provided with a plurality of rolling elements as a transmission system from the input shaft to the output shaft. In a transmission type transmission, a pressing force corresponding to a load torque acting on at least one of the input shaft and the output shaft is applied to the rolling elements by a pair of face cams arranged at opposing positions and interposing rolling elements. A pressing force generating device to be applied to a surface, wherein one of the face cams has a rotating cam provided with a V-groove for contacting a roller as the rolling element along the axial direction, and the face cam main body is rotatable. This is because there are multiple supports around the axis.

  Here, the “pressing force generator” in this specification refers to a friction transmission type that uses a rolling element such as a conical wheel, a sphere, and a disk, and moves the friction contact point to change the turning radius steplessly. In a transmission, a device that directs a pressing force according to a load torque acting on an input shaft or an output shaft to a contact surface. For example, there is a structure in which a pair of face cams each having a plurality of V-grooves arranged in the radial direction are opposed to one surface of the face cam body, and a roller as a rolling element is interposed between the facing V-grooves.

  The “rotating cam” is a member having a V-groove on one end surface, and is a member that is rotatably supported on one surface of the face cam body. As a shape, a cylindrical shape in which a V-groove is formed on one end surface is common, but the shape of the peripheral surface and the other end surface is not particularly limited, and the V-groove surface is determined by an axis parallel to the axis of the face cam body What is necessary is just to be able to support the rotation without changing the inclination angle.

  As a means for supporting, for example, a circular or partially circular hole into which the rotating cam is fitted is provided in the face cam main body, or it is rotatably supported by an integral or separate shaft. The rotary cam may be provided directly on the face cam body so as to be rotatable, or may be provided via a spring such as a disc spring or a coil spring. By providing a spring, it becomes possible to function as a pressing force generator at the stage of no load or light load, or to prevent a stall due to an initial slip between the rolling elements by applying a preload to the contact surface of the rolling elements. . Furthermore, since the spring is interposed on the other end face side of the rotating cam with a small area, the frictional resistance of the rotating cam can be reduced to facilitate rotation. Further, an elastic body such as rubber may be used in addition to the spring, and the rotational resistance of the rotating cam can be reduced through a metal plate or the like.

  A “retainer” refers to a member that is mounted between a pair of face cams to hold a roller or a rotating cam interposed between opposing V grooves. In the present invention, since each rotary cam is rotatably supported by the face cam body, the retainer is provided with a through-hole that is externally fitted to the roller or the rotary cam. The cage may have a structure in which the function is provided in one or both of the pair of face cam bodies.

“Supporting portion” refers to a member provided on the rotating cam so as to be in contact with both ends of the roller located on the V groove of the rotating cam. This support portion has the same function as the cage, and prevents the roller from protruding outward due to centrifugal force when the face cam rotates around its rotation axis. The purpose is to regulate movement. The support portion may be provided integrally with the rotating cam, or a separate cylindrical member or ring-shaped member may be externally fitted so as to cover both ends of the V groove in the groove direction.

  When the pair of face cams are twisted in response to an increase in load torque, the rotary cam pressure control device according to the present invention rotates the rotary cam that is rotatably supported by one face cam. Both the V-groove surface and the V-groove surface of the other face cam can be rolled in a very stable state in which the rollers interposed therebetween maintain line contact.

Therefore, the apparatus of the present invention can exhibit the advantage of the roller that it can cope with a large load capacity due to line contact at a substantially high load. Moreover, slip stall can be prevented even when shocking load torque fluctuates, and highly efficient and stable power transmission can be achieved. In addition, since it is not necessary to consider the spin of the rollers, the pitch circle in which the rollers are arranged can be reduced to increase the lead angle. For example, the degree of freedom in design increases, and the power transmission system in the friction transmission type transmission device It has a very beneficial effect as an element.

According to the present invention, as a pressing force generating device in a friction transmission type transmission, a rotating cam provided with a V-groove for contacting a roller in the axial direction on one of the face cams is supported by a plurality of rotations. The above-mentioned problem has been solved.

  FIGS. 1A and 1B show an embodiment of a rotary cam pressure adjusting device 1 according to the present invention. One face cam 2 constituting a pair of face cams 2 is provided with a V groove 31. This is a structure in which a plurality of (eight) rotating cams 3 are rotatably provided on a concentric circle of the face cam body 21. The other face cam 2 has a V-groove 31 formed on one surface of the face cam body 21. By interposing the roller 4 between the opposing V grooves 31 of the pair of face cams 2, a pressing force corresponding to the rotational torque of the face cam 2 is generated in the axial direction of the face cam 2. As a means for supporting the roller 4 interposed between the V grooves 31, for example, a cage 5 in which rectangular through holes 51 as shown in FIG. 2 are arranged concentrically is provided between the pair of face cams 2.

In the conventional pressing force generating device, at the stage of transition from the unloaded state of FIG. 3A to the loaded state of FIG. From the line contact to the point contact with respect to the groove 31 surface. In the present invention, since the rotary cam 3 is provided to be rotatable, each V-groove 31 is shifted while maintaining a line contact with the roller 4 as shown in FIG. That is, the rotary cam 3 has a rotation axis perpendicular to the rotation axis of the roller 4 and rotates at the same angle β in the opposite direction to the angle α in the direction in which the opposing V grooves 31 are twisted by the load torque. As a result, even when an angular difference α is generated between the opposing V grooves 31 sandwiching the roller 4 due to the load torque, the roller 4 is interposed, so that the V on the rotary cam 3 side with respect to the surface of the counterpart V groove 31. The surface of the groove 31 rotates and becomes parallel, and both V-groove 31 surfaces come into line contact with the roller 4.

FIGS. 4A and 4B show another example of the rotary cam pressure adjusting device 1 according to the present invention, in which support portions 32 are provided on both ends in the groove direction of the V groove 31 of the rotary cam 3. With this support portion 32, the movement of the roller 4 in the axial direction can be restricted and held on the surface of the V-groove 31 as shown in FIG. By providing the rotation cam 3 with the support portion 32, it can be used as an alternative to the retainer 5 as described above. However, the retainer 5 may be separately provided to hold the roller 4 and the rotation cam 3.

FIG. 5 shows still another example of the rotary cam pressure adjusting device 1 according to the present invention, in which the rotary cam 3 is rotatably supported by the face cam body 21 via a spring 33. The spring 33 shown in this example is a coil spring, and urges the rotating cam 3 toward the V groove 31 of the facing face cam 2. The provision of the spring 33 is intended to give a preload to the rolling elements as described above. For this reason, when a load is applied, it is preferable to provide a spring 33 so that the rotary cam 3 can be directly supported by the face cam body 21 as in this example so as not to lower the rigidity.

  The rotary cam pressure adjusting device 1 according to the present invention can make the most of its functions particularly in a continuously variable transmission 6 having a traction drive structure as shown in FIG. This is because the traction drive generates a tangential force between the metals via the traction oil, so that a pressing force is required between the metals, and the pressing force must be reliably increased according to the load torque.

This continuously variable transmission 6 uses a planetary shift cone 61 as a rolling element. The rotary cam pressure adjusting device 1 is provided between an input shaft 62 and an input plate 63, and the input plate 63 and the transmission cone are provided. A pressing force is applied to the contact surface of the 61 with the input unit 64. The rotary cam pressure adjusting device 1 is provided between the output ring 66 and the output shaft 67 in order to apply a pressing force to the contact surface between the output portion 65 of the transmission cone 61 and the output ring 66. In the continuously variable transmission 6 shown in the present example, the rotary cam pressure adjusting device 1 is provided on the bottom side of the transmission cone 61 for the purpose of applying a pressing force to the transmission portions of the transmission ring 68 and the transmission cone 61. In this structure, an axial pressing force is applied from the bottom of the transmission cone 61.

(A) (b) is a top view which shows the Example of a pair of face cam in the rotating cam pressure regulator which concerns on this invention. (Example 1) It is a top view which shows an example of the holder | retainer interposed between a pair of face cams. (A) is a perspective view showing the relationship between the roller and the V groove when no load is applied to the face cam, (b) is a perspective view showing the relationship between the roller and the V groove when a load is applied to the conventional face cam. (C), It is a perspective view perspective view which shows the relationship between a roller and a V groove when a load is applied to the face cam of the rotary cam pressure regulator according to the present invention. (A) (b) is a perspective view which shows the other Example of a pair of face cam in the rotating cam pressure regulator which concerns on this invention, (c) is a perspective view which shows the state which mounted the roller in the rotating cam. . (Example 2) It is a fragmentary sectional view which shows the further another Example of the rotating cam pressure regulator which concerns on this invention. Example 3 It is sectional drawing which shows the Example of the continuously variable transmission using the rotary cam pressure regulator which concerns on this invention. (Example 4)

Explanation of symbols

1 Rotary cam pressure regulator 2 Face cam
21 Face cam body 3 Rotating cam
31 V groove
32 Support part
33 Spring 4 Roller 5 Cage 6 Continuously variable transmission
61 Shift cone
62 Input shaft
63 Input board
64 input section
65 Output section
66 Output ring
67 Output shaft
68 Shifting ring

Claims (4)

  In a friction transmission type transmission device having a plurality of rolling elements as a transmission system from an input shaft to an output shaft, at least the input shaft and the output shaft are provided by a pair of face cams arranged at opposing positions and interposing rolling elements. A pressing force generating device that applies a pressing force according to a load torque acting on one side to a contact surface of the rolling element, wherein one of the face cams applies a roller as the rolling element along an axial direction. A rotary cam pressure adjusting device characterized in that a plurality of rotary cams each having a V groove to be contacted are rotatably supported around the axis of the face cam body.   2. A cage in which a through hole for rotatably supporting either one of each roller or each rotary cam around a rotation axis of the rotary cam is mounted between a pair of face cams. Rotating cam pressure regulator.   The rotary cam pressure adjusting device according to claim 1 or 2, wherein the rotary cam is provided with support portions at both ends of the V groove in the groove direction.   4. The rotary cam pressure adjusting device according to claim 1, wherein the rotary cam is rotatably supported on the face cam body via a spring.

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