JP2007247852A - Continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact continuously variable transmission efficiently transmitting large torque. <P>SOLUTION: The continuously variable transmission comprises: a first rotational shaft rotatably supported by a casing; a second rotational shaft rotatably supported by the casing; a V-pulley 4 supported by the first rotational shaft and having groove variable in width; a ring which is engaged with the V pulley 4 and whose outer circumference is supported; and a mechanism moving the ring around the second rotational shaft. The mechanism has an arm 40 turnable around the second rotational shaft, and at least three guide rollers 1a, 1b disposed to the outer circumference of the ring, guide rollers 1a, 1b are positioned at fixed points on the arm 40, and the arm 40 is constituted of a pair of stepped plates 42, 44 interposing a stepped spacer 46 therebetween. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a continuously variable transmission used in automobiles and various industrial machines.

  Many ideas have been made for continuously variable transmissions (CVTs) (see Non-Patent Document 1). Recently, the half-toroidal method (FIG. 10) has attracted attention, but the direction of practical use is the metal belt method (FIG. 11).

  The problem of the traction drive device is to transmit a large torque efficiently with a compact size. In order to obtain a compact and large transmission torque, a large contact force may be applied. However, if the contact stress is too large, the life is shortened. If the contact area is designed to be large in order to reduce the contact stress, the spin component of the contact portion increases and the transmission efficiency decreases. The above-mentioned half toroidal type and metal belt type solve these problems to some extent. But not perfect, each has its own drawbacks. In the half toroidal type, the power roller swings and shifts while being pressed against the input / output disk surface. A large contact pressure acts here, and seizure occurs when an oil film is not formed. In order to avoid this, it is necessary to improve the surface roughness. However, in order to process a large spherical surface with high accuracy, the cost must be high. Furthermore, it is long in the axial direction because of its structure, and it is impossible to mount it on an FF vehicle. On the other hand, in the metal belt system, a large number of elements are stacked to facilitate bending, and the torque is transmitted by being pressed against the V pulley. Basically, wear is inevitable because the pulley and belt are in metal contact.

The present applicant has previously proposed a traction drive type continuously variable transmission having a structure that has not been achieved by combining a transmission ring and a V pulley as a compact and capable of efficiently transmitting large torque, which has solved the above-mentioned problems. (Patent Document 1).
JP 2005-172065 A Machida, Imanishi, "Development of Traction Drive Type Continuously Variable Transmission Power Troth Unit 2nd Report-Comparison of Half Toroidal CVT and Full Toroidal CVT", NSK Technical Journal No. 670 (2000), NSK Ltd.

  In the continuously variable transmission described in Patent Document 1, there are two guide rollers, a ring, and an arm that swing around the center of the output shaft. This arm is provided with a two-stage thickness so that it can enter the inner diameter side of the pulley when swinging, and it is an arm mechanism with a 7-piece structure because of the assembly of the guide roller. . The arm mechanism having a conventional structure is provided with a hole for a guide roller and an output gear and a positioning pin. For this reason, when manufacturing an arm composed of two pieces on one side, it is necessary to process each hole position with high accuracy, and there is a problem to be solved in manufacturing.

  An object of the present invention is to eliminate the above-described problems in the continuously variable transmission of the type described in Patent Document 1.

  The continuously variable transmission of the present invention includes a first rotating shaft that is rotatably supported by a casing, a second rotating shaft that is rotatably supported by the casing, and a pulley width that is supported by the first rotating shaft. Is constituted by a variable V pulley, a ring engaged with the V pulley and supported on the outer periphery, and a mechanism for moving the ring around the second rotation axis, and the mechanism includes the second rotation axis. An arm rotatably supported around the ring, and at least three guide rollers disposed on an outer periphery of the ring, each guide roller being positioned at a fixed point on the arm, and the arm serving as a stepped spacer. It is characterized by comprising a pair of stepped plate members interposed.

  The present invention has the following advantages over the prior art. Compared to the half toroidal type, even if the contact area is increased, the spin component is small and the efficiency is good. Since spherical processing like the half toroidal type is unnecessary, the cost is low. The axial length is shorter than that of the half toroidal type, and it is easy to apply to FF vehicles. In addition, the structure is simpler and lower in cost than the metal belt type. An oil film is formed between the pulleys and there is no wear compared to the metal belt type, and therefore the life is long.

  In addition, since the arm is composed of a pair of stepped plate members and stepped spacers, workability and assemblability are improved, and as a result, costs are reduced. Further, the rigidity of the arm is increased as compared with the case where it is configured by a flat plate material.

  Embodiments of the present invention will be described below with reference to the drawings. For convenience of explanation, a comparative example manufactured in the course of development of the present invention will be described first. The basic structure is the same in the comparative example and the examples described later, and only the structure of the arm is different.

  FIG. 1 is a front view of a continuously variable transmission of a comparative example, and FIG. 2 is a longitudinal sectional view. As can be understood from these drawings, a V-groove is formed by a pair of pulleys 4 movable in the axial direction, and the ring 3 is sandwiched. Since the ring 3 has gear-like teeth on the outer periphery, it will be referred to as a toothed ring below. As shown in FIG. 2, a rotary shaft 6 and a rotary shaft 7 that are parallel to each other are rotatably supported in the casing 10 via bearings. These rotary shafts 6 and 7 transmit torque between each other. When one rotary shaft (6 or 7) is an input shaft, the other rotary shaft (7 or 6) is an output shaft.

  As shown in FIG. 2, a small gear 2 is fixed to the first rotating shaft 6, and the small gear 2 meshes with a toothed ring 3. The toothed ring 3 has teeth that mesh with the teeth of the small gear 2 and a smooth cylindrical guide surface 8 (see FIG. 5). The guide surface 8 contacts the guide rollers 1a, 1b, and 1c. The guide of the toothed ring 3 employs a guide roller that rolls in contact with the outer peripheral surface of the toothed ring 3 as shown in the figure, and since the contact load with the toothed ring 3 is small, A sliding bearing (shoe) that makes sliding contact may be used. FIG. 1 shows three guide rollers 1a, 1b, and 1c, and FIG. 2 shows only two of them, that is, only the guide roller 1a and the guide roller 1c.

  The guide rollers 1a and 1b are rotatably supported by the arm 14 through shafts and bearings, respectively. The guide roller 1c is composed of a pair of discs attached to both sides of the small gear 2. Therefore, the positional relationship between the guide rollers 1a, 1b, and 1c is fixed. In other words, the guide rollers 1a, 1b, 1c are located at fixed points on the arm 14. The guide roller 1b appearing at the left end of FIG. 1 has a role of preventing the toothed ring 3 from swinging. The arm 14 is pivotally supported by the sleeve 18 of the casing 10 coaxially with the rotating shaft 6.

  The second rotating shaft 7 supports a pair of pulleys 4. Since each pulley 4 is fitted to the second rotating shaft 7 via the ball spline 12, each pulley 4 can move in the axial direction of the rotating shaft 7 and cannot rotate relative to the rotating direction, that is, torque transmission. Is possible. Each pulley 4 includes a pulley width adjusting mechanism 30. The pulley width adjusting mechanism 30 is a ball screw type, and is formed by a screw shaft 32 having a screw groove formed on the outer periphery, a nut 34 having a screw groove formed on the inner periphery, a screw groove of the screw shaft 32, and a screw groove of the nut 34. And a plurality of balls 36 that circulate in the circulation path. The screw shaft 32 is rotatably supported by the boss portion of the pulley 4 via the bearing 16. Here, a case where an angular ball bearing is employed so as to receive an axial force by the pulley width adjusting mechanism 30 is illustrated.

  The screw shaft 32 includes a gear 38, and the pair of gears 38 is assembled to the connecting shaft 20. Therefore, the pair of gears 38 rotate only in synchronization. As a result, the screw shafts 32 in the left and right pulley width adjusting mechanisms 30 in FIG. 2 rotate in the same direction. Since the nut 34 is fixed to the casing 10, when the gear 38 is rotated via the connecting shaft 20 by an external drive mechanism (not shown), the rotational motion is converted into the axial movement of the screw shaft 32, and the rotation of the gear 38 is performed. Depending on the direction, an axial force is generated that pushes the pulley 4 through the bearing 16 or moves away from the pulley 4. Since the right pulley width adjusting mechanism 30 and the left pulley width adjusting mechanism 30 in FIG. 2 are reverse screws, when the screw shaft 32 rotates in the same direction, they move in opposite directions. In this way, the pair of pulleys 4 move in the direction of approaching or separating, and the pulley width of the V groove changes.

  By controlling the connecting shaft 20 to which the gear 22 meshed with the gear 38 is rotated in conjunction with the turning of the arm 14, the guide roller group of the rotating shaft 6 is linked to the axial movement of the pulley 4. The contact point between the two can be moved while turning around the center and bringing the toothed ring 3 into contact with the pulley 4.

  Since the toothed ring 3 is constrained from the outer periphery by three guide rollers 1a, 1b, and 1c, it can be rotated without a central axis (coreless roller). The guide rollers 1a, 1b, and 1c are connected by an arm 14, and the rotation center of the toothed ring 3 can be moved around the center of the rotation shaft 6 by turning the arm 14. Therefore, the teeth cut on the outer periphery of the toothed ring 3 are always in a state of being engaged with the small gear 2. If the pulley 4 and the arm 14 are controlled so that there is no gap between the toothed ring 3 and the pulley 4, the contact point with the pulley 4 changes as the toothed ring 3 moves around the center of the rotating shaft 6. In addition, the rotation speed of the small gear 2 can be continuously changed with respect to the fixed rotation speed of the pulley 4. In this way, a so-called CVT is configured.

  When the rotary shaft 7 that supports the pulley 4 is set as the input side, the state in which the toothed ring 3 is pushed becomes a deceleration state. If the transmission torque is the same, the pinching force by the pulley 4 when the toothed ring 3 is pushed in should be increased. Conversely, when the contact point between the toothed ring 3 and the pulley 4 is on the large diameter side, It may be small. When considering the bending stress of the pulley 4 due to the pinching force, this method using the pulley 4 as an input, which can reduce the pinching force at the time of large diameter contact, is better than the output. When a rotational force is input from the input shaft, that is, the rotating shaft 7 in the direction of the arrow shown in FIG. 6, a force is applied from the pulley 4 to the toothed ring 3, and a force having substantially the same magnitude is applied from the small gear 2. To do. Since the reaction force from the small gear 2 acts in the direction of pushing the toothed ring 3 between the pulleys 4, the contact force automatically increases as the transmission torque increases.

  As shown in FIGS. 3 and 4, the arm 14 is configured by combining four plate members 24a, 24b, 26a, and 26b and three spacers 28a, 28b, and 28c. That is, the inner pair of plate members 26a and 26b are held at a narrow interval via the spacer 28b, and the outer pair of plate members 24a and 24b are held outside at a wide interval via the spacers 28a and 28b. The plate members 24a, 24b, 26a, and 26b are flat and are fastened to the spacers 28a, 28b, and 28c with screws. Further, all the plate members 24a, 24b, 26a, and 26b are positioned with high accuracy by passing through the positioning pins.

  As shown in FIG. 2, the guide roller 1 a is located away from the pulley 4. As can be understood from FIG. 1, the arm 14 oscillates around the rotation shaft 6, so that the guide roller 1 a shown in the upper part of the figure does not enter between the pulleys 4. On the other hand, the guide roller 1b shown on the left side of FIG. 1 must be able to enter between the pulleys 4 as the arm 14 swings. FIG. 5 shows a state in which the toothed ring 3 has entered the innermost diameter side between the pulleys 4 together with the guide roller 1b. For this purpose, the guide roller 1b is arranged in a narrowly spaced portion composed of the above-described plate members 26a and 26b.

  Next, the embodiment shown in FIG. 6 will be described. Since the basic configuration of the continuously variable transmission is the same as that of the above-described comparative example and the main difference is the structure of the arm, the arm will be described below. As shown in FIGS. 7 and 8, the arm 40 is configured by two stepped plate members 42 and 44 and one stepped spacer 46. Each stepped plate member 42, 44 has an irregular endless shape that is almost circular as shown in FIG. 6, and is fastened with a bolt 48 via a stepped spacer 46, as shown in FIGS. A part with a wide mutual space and a narrow part are created. A guide roller 1a is rotatably attached to the wide interval portion via a shaft 50 and a bearing 52, and a guide roller 1b is rotatably attached to a narrow interval portion via a shaft 54 and a bearing 56. .

  When the spacer 46 has a structure as shown in FIG. 9A, when the arm 40 shown in FIG. 6 bites into the pulley 4, the stepped plate members 42 and 44 receive a load as shown by an arrow in FIG. 9B. There is a possibility of stretching. By using the stepped spacer 46 between the pair of stepped plate members 42 and 44, it is possible to compensate for the lack of rigidity when a load is applied to the arm 40 as shown by the arrow in FIG.

Front view of continuously variable transmission Partial sectional view of the transmission of FIG. III-III sectional view of FIG. 1 is a longitudinal sectional view of an arm mechanism in the apparatus of FIG. 2 is a partially enlarged view including a pulley, a toothed ring, and a guide roller in the apparatus of FIG. The front view of the continuously variable transmission which shows embodiment of this invention VII-VII sectional view of FIG. Vertical section of arm Longitudinal sectional view similar to FIG. 8 for explaining the rigidity increase Sectional view showing conventional technology (A) is sectional drawing which shows the prior art, (B) is a perspective view

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Guide roller 2 Small gear 3 Toothed ring 4 Pulley 6 Rotating shaft 7 Rotating shaft 8 Guide surface 10 Casing 12 Ball spline 14 Arm 16 Bearing 18 Sleeve 20 Connecting shaft 22 Gear 24a, 24b Plate material 26a, 26b Plate material 28a, 28b Spacer 30 Pulley width adjustment mechanism 32 Screw shaft 34 Nut 36 Ball 38 Gear 40 Arm 42, 44 Stepped plate material 46 Stepped spacer 48 Bolt 50, 54 Shaft 52, 56 Bearing

Claims (1)

  A first rotary shaft rotatably supported by the casing; a second rotary shaft rotatably supported by the casing; a V pulley having a variable pulley width supported by the first rotary shaft; and a V pulley And an arm that is supported so as to be pivotable around the second rotation axis, and a ring that is supported on the outer periphery and a mechanism for moving the ring around the second rotation axis. A pair of stepped plate members having at least three guide rollers disposed on the outer periphery of the ring, each guide roller being positioned at a fixed point on the arm, and the arm interposing a stepped spacer. A continuously variable transmission configured.

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