JP2007271042A - Continuously variable transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate a defect such as enlargement due to an increases in strength and capacity of a transmission mechanism (a pulley width adjusting mechanism) and the deterioration in a gear shift response. <P>SOLUTION: A continuously variable transmission comprises an input shaft 12 freely rotatably supported by a casing, an output shaft 28 freely rotatably supported by the casing, a V pulley composed of a pair of pulley members supported by the input shaft 12 so as to be axially displaceable and torque-transmittable, a toothed ring 18 which is clamped by the V pulley and which keeps the outer periphery supported by a plurality of guide rollers 22a, 22b, 22c, 22d, an output gear 26 fixed to the output shaft 28 and meshed with a gear provided to the outer periphery of the toothed ring 18, and an arm 24 freely rotatably supporting a plurality of guide rollers 22a, 22b, 22c and turnable around an axial center of the output shaft 28, wherein the arm 24 is provided with an actuator 46 for exerting a moment around the axial center of the output shaft 28. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

  For continuously variable transmissions for automobiles, mainly metal belt type CVT and half toroidal type CVT (traction drive type) have been put into practical use. The present applicant, as a continuously variable transmission of a new mechanism that solves the problems (smaller and lighter, improved efficiency) of the conventional continuously variable transmission, a toothed ring is clamped between a pair of pulleys, the pulley and the toothed A continuously variable transmission that enables power transmission and continuously variable transmission with a ring is proposed (Patent Documents 1 and 2).

The main structure of the continuously variable transmission described in Patent Documents 1 and 2 is as shown in FIGS. A pair of pulley members 2 are engaged with the input shaft 1 by a power transmission means (ball spline or the like) that can be displaced in the axial direction and arranged coaxially. A toothed ring 3 having a gear and a cylindrical rolling surface on the outer periphery is clamped between the pulley members 2, and power is transmitted to the toothed ring 3 by friction between the pulley member 2 and the side surface of the toothed ring 3. . The rotation of the toothed ring 3 is transmitted to the output shaft 4 by gear transmission through the output gear 6. A plurality of guide rollers 5 in contact with the outer peripheral rolling surface of the toothed ring 3 are arranged on the outer periphery of the toothed ring 3, and these guide rollers 5 are arms that can rotate around the axis of the output gear 6 (output shaft 4). 7 is rotatably supported. The mechanism including the guide roller 3 and the arm 7 enables the toothed ring 3 to rotate without a support bearing, and the center O of rotation rotates around the axis of the output shaft 4 with a shift. The gear ratio is continuously changed by changing the pulley width using a cam or a feed screw. A contact portion between the pulley member 2 and the toothed ring 3 is indicated by a symbol P in FIG.
JP 2004-263857 A JP 2005-226840 A

  The normal force required for friction transmission is obtained by the reaction force from the gear acting on the toothed ring and the wedge effect formed by the pulley, and the smaller the pulley inclination angle θ (see FIG. 6), the larger the normal force is. can get. On the other hand, when performing a shift that increases the gear ratio, in other words, when the toothed ring is displaced radially outward, it is necessary to apply an axial load to the pulley that can overcome this normal force. For this reason, problems such as an increase in the strength of the speed change mechanism (pulley width adjusting mechanism) or an increase in the actuator capacity and a reduction in the speed change response are caused.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a continuously variable transmission that eliminates the above-mentioned problems, that is, problems such as an increase in strength of a speed change mechanism (pulley width adjusting mechanism) or an increase in actuator capacity and a reduction in speed change response. There is to do.

  A continuously variable transmission according to the present invention includes a first rotating shaft rotatably supported by a casing, a second rotating shaft rotatably supported by the casing, and axial displacement and torque on the first rotating shaft. A V pulley constituted by a pair of pulley members supported so as to be able to transmit, a toothed ring clamped by the V pulley and supported by a plurality of guide rollers on the outer periphery, and an outer periphery of the toothed ring fixed to the second rotating shaft A small gear that meshes with a gear provided on the arm, and an arm that rotatably supports a plurality of guide rollers and that can turn around the axis of the second rotating shaft, and the axis of the second rotating shaft is included in the arm. An actuator for applying a surrounding moment is provided.

  As an actuator, for example, a linear actuator by hydraulic or pneumatic pressure (Claim 2), a linear actuator by a combination of a motor and a ball screw (Claim 3), or a pitch circle center fixed to an arm is the axis of the output shaft. It is possible to employ a rotary actuator (Claim 4) constituted by a large gear that coincides with the pin, a pinion that meshes with the large gear, and a motor that rotationally drives the pinion.

  The actuator drives the arm in both the clockwise and counterclockwise directions around the axis of the second rotating shaft. When the gear ratio is changed from large to small by widening the pulley width by the speed change mechanism, there is no problem with speed change because the force required to move the pulley in the axial direction is small. However, by pressing the toothed ring inwardly in the pulley radial direction, excessive slip (gross slip) at the contact portion between the pulley and the toothed ring can be prevented, and the transmission torque capacity can be improved. When changing the gear ratio from small to large, the actuator applies a turning load to the arm and presses the toothed ring outward in the pulley radial direction. Thereby, the speed change property when changing the speed ratio from small to large is improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, as shown in FIG. 5, the basic structure of the continuously variable transmission is a structure in which a ring 18 is sandwiched between grooves of a V pulley formed of a pair of pulley members 14 that are movable in the axial direction. Since the ring 18 has gear teeth on the outer periphery, the ring 18 is hereinafter referred to as a toothed ring. In the casing 10, rotating shafts 12 and 28 parallel to each other are rotatably supported via bearings. When torque is transmitted between the rotary shafts 12 and 28 and one rotary shaft (12 or 28) is used as an input shaft, the other rotary shaft (28 or 12) is used as an output shaft.

  The rotating shaft 12 supports a V pulley composed of a pair of pulley members 14. Each pulley member 14 can be moved in the axial direction of the rotary shaft 12 by a ball spline 16 and can be locked in the rotational direction to transmit torque. Each pulley member 14 includes a pulley width adjusting mechanism 34. The pulley width adjusting mechanism 34 illustrated in FIG. 5 is a ball screw type, and a spiral passage formed in the inner periphery of the nut 36 and a spiral groove formed in the outer periphery of the screw shaft 38 form a circulation path to circulate a plurality of balls. It is designed to run. The nut 36 is fixed to a stationary member such as the casing 10. Therefore, the screw shaft 38 is displaced in the axial direction as it rotates. The tip of the screw shaft 38 is in contact with the outer ring of the bearing 32 fitted to the boss portion of the pulley member 14.

  A gear 40 is fixed to the screw shaft 38. The gear 40 meshes with a gear 44 fixed to a transmission shaft 42 that is rotatably supported by the casing 10. When the transmission shaft 42 is rotated, the screw shaft 38 is rotated, and at the same time, the screw shaft 38 is moved in the axial direction to the right or left in the drawing depending on the rotation direction. Since the ball screws in the left and right pulley width adjusting mechanisms 34 in FIG. 5 are reverse to each other, the screw shafts 38 move in the opposite directions with the rotation of the transmission shaft 42 and therefore the gear 44. . In this way, the pair of pulley members 14 moves in the direction of approaching or separating, and the groove width of the V pulley changes.

  A small gear 26 is fixed to the rotary shaft 28. The small gear 26 meshes with the toothed ring 18. The toothed ring 18 has teeth that mesh with the teeth of the small gear 26 and a smooth cylindrical guide surface 20, and contacts the guide roller at the guide surface 20. As shown in FIG. 1, four guide rollers 22a, 22b, 22c, and 22d are provided. In FIG. 5, two of them, that is, the guide roller 22a and the guide roller 22d appear. The guide rollers 22a, 22b, and 22c are rotatably attached to the arm 24 through pins and bearings, respectively. The guide roller 22d is composed of a pair of disks arranged on both sides of the small gear 26.

  As shown in FIG. 1, the arm 24 has a ring shape, and guide rollers 22a, 22b, 22c, and 22d are arranged at intervals of approximately 90 °. The positional relationship between these guide rollers is fixed. The at least one guide roller is preferably arranged so as to contact the toothed ring around 180 ° around the center of the toothed ring of the contact portion P between the pulley member and the toothed ring. As shown in FIG. 5, the arm 24 is composed of two plates, and is rotatably supported by the sleeve 30 of the casing 10 coaxially with the rotary shaft 28.

  Since the toothed ring 18 is constrained from the outer periphery by four guide rollers 22a, 22b, 22c, and 22d, it can rotate without a central axis (coreless roller). By rotating the arm 24 carrying the guide rollers 22a, 22b, 22c, the rotation center O of the toothed ring 18 can be moved around the axis of the rotation shaft 28. The teeth on the outer periphery of the toothed ring 18 are always in mesh with the small gear 26. If the pulley member 14 and the arm 24 are controlled so that there is no gap between the toothed ring 18 and the pulley member 14, the pulley member moves as the toothed ring 18 moves around the axis of the rotary shaft 28. 14 is changed, and the speed of the pulley member 14 can be continuously changed with respect to a constant rotation speed of the small gear 26. In this way, a so-called CVT is configured.

  For example, when the rotary shaft 12 is on the input side, the state where the toothed ring 18 is pushed inward in the radial direction of the pulley member 14 is a deceleration state as shown in FIG. When a rotational force is input from the pulley member 14, a force acts on the toothed ring 18 from the pulley member 14, and a force of almost the same magnitude acts on the small gear 26. Since the reaction force from the small gear 26 acts in the direction of pushing the toothed ring 18 between the pulley members 14, the contact force automatically increases as the transmission torque increases.

  An actuator for turning the arm 24 carrying the guide rollers 22a, 22b and 22c and moving the rotation center O of the toothed ring 18 around the axis of the rotation shaft 28 is provided. The embodiment shown in FIGS. 1 to 3 is an example in which a linear actuator is adopted as the actuator. Specific examples of the linear actuator include a hydraulic cylinder, a pneumatic cylinder, a combination of a motor and a ball screw, and the like. Here, the actuator 46 is fixed to the casing 10, and the arm 24 is provided with a joint 52 for transmitting the load from the actuator 46 to the arm 24. The joint 52 needs to have a function of absorbing the difference between the linear motion of the actuator 46 and the turning motion of the arm 24. As an example, FIG. 2 shows a structure in which a cross shaft is provided at the tip of the actuator rod 48 and the roller 50 is rotatably mounted so that the roller 50 rolls in the U-shaped groove of the joint 52 having a U-shaped cross section. It is shown.

  FIG. 4 shows an embodiment in which a rotary actuator is employed as the actuator. Here, the case of gear transmission is illustrated. In other words, a large gear (a part) 54 whose pitch circle center coincides with the axis of the output shaft 28 is fixed to the arm 24, and by rotating a pinion 56 that meshes with the large gear 54, a turning moment is applied to the arm 24. It is made to act. A motor (not shown) for driving the pinion 56 is fixed to the casing 10.

  Regardless of the type of actuator, the actuator can control the pressurizing direction and the applied pressure in accordance with the transmission ratio, the transmission command, the transmission torque, and the like.

Schematic side view of continuously variable transmission showing an embodiment II view of FIG. Side schematic view similar to FIG. 1 showing the state of a small gear ratio Side surface schematic diagram of continuously variable transmission showing another embodiment Vertical section of continuously variable transmission Sectional view of the main part of a continuously variable transmission showing conventional technology Side schematic diagram of continuously variable transmission showing conventional technology

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Casing 12 Rotating shaft 14 Pulley member 16 Ball spline 18 Toothed ring 20 Guide surface 22a, 22b, 22c, 22d Guide roller 24 Arm 26 Small gear 28 Rotating shaft 30 Sleeve 32 Bearing 34 Pulley width adjusting mechanism 36 Nut 38 Screw shaft 40 Gear 42 Transmission shaft 44 Gear 46 Actuator 48 Rod 50 Roller 52 Joint 54 Large gear 56 Pinion

Claims (4)

A first rotating shaft rotatably supported by the casing;
A second rotating shaft rotatably supported by the casing;
A V pulley constituted by a pair of pulley members supported so as to be capable of axial displacement and torque transmission on the first rotating shaft;
A toothed ring clamped by a V pulley and supported by a plurality of guide rollers on the outer periphery;
A small gear meshed with a gear fixed to the second rotating shaft and provided on the outer periphery of the toothed ring;
An arm that rotatably supports a plurality of guide rollers and pivots around the axis of the second rotating shaft, and an actuator that applies a moment around the axis of the second rotating shaft to the arm. Continuously variable transmission.   2. The continuously variable transmission according to claim 1, wherein the actuator is a linear actuator by hydraulic pressure or pneumatic pressure.   2. The continuously variable transmission according to claim 1, wherein the actuator is a linear motion actuator using a combination of a motor and a ball screw.   The actuator is a rotary actuator composed of a large gear whose pitch circle center fixed to the arm coincides with the axis of the second rotation shaft, a pinion that meshes with the large gear, and a motor that rotationally drives the pinion. The continuously variable transmission according to claim 1.

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