JP2015038371A - Continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent degradation of durability caused by overspeed rotation of a continuously variable transmission, by increasing a change gear ratio in failure of an actuator for gear change of the continuously variable transmission.SOLUTION: A center of gravity G of an eccentric disc 13 of an eccentricity variable mechanism 14 of a continuously variable transmission T, exists at a minor arc Ami side of an outer peripheral circle of the eccentric disc 13 with respect to a secant S connecting an axis L of an input shaft 11 connected to a driving source E and a center O1 of an eccentric cam 25 integrated with the input shaft 11 in a gear change ratio of a top drive for obtaining a maximum vehicle speed. Thus when an actuator A is failed, holding power of the eccentric disc 13 by a pinion 32 vanishes, and the eccentric disc 13 is relatively rotated to the eccentric cam 25 by centrifugal force F1, the eccentric disc 13 is relatively rotated to a change gear ratio increase direction (geared neutral side), thus the overspeed rotation of the continuously variable transmission T is prevented, and durability can be secured.

Description

  The present invention includes an input shaft connected to a drive source, an output shaft connected to a drive wheel, a disc-shaped eccentric disk that rotates integrally with the input shaft, and a rocking motion on the output shaft via a one-way clutch. An oscillating arm that is movably supported, a connecting rod that reciprocates by connecting the eccentric disc and the oscillating arm, and an eccentric amount variable mechanism that changes an eccentric amount of the eccentric disc relative to the axis of the input shaft. The present invention relates to a continuously variable transmission.

  In such a continuously variable transmission, the eccentric disk around the input shaft is rotated when the eccentric disk rotates relative to the eccentric cam to change the transmission ratio by matching the position of the center of gravity of the eccentric disk with the center of the eccentric cam. The following Patent Document 1 prevents the occurrence of vibration by preventing the inertial moment of inertia from changing, and prevents the load from being applied to the actuator that changes the gear ratio by the centrifugal force acting on the center of gravity of the eccentric disk. Is known.

WO2013 / 008624A1

  By the way, in the conventional continuously variable transmission, since the position of the center of gravity of the eccentric disk coincides with the center of the eccentric cam, a load is applied to the actuator that changes the gear ratio by the centrifugal force acting on the center of gravity of the eccentric disk. Absent. Therefore, when the actuator fails and the eccentric disk cannot be held with respect to the eccentric cam, the eccentric disk maintains the amount of eccentricity when the actuator fails.

  However, assuming that the actuator fails during high-speed rotation of the engine, in order to prevent over-rotation of each member of the continuously variable transmission and avoid adverse effects on durability, the eccentricity when the actuator fails Rather than maintaining the eccentric amount of the disc as it is, the eccentric amount of the eccentric disc is decreased to quickly increase the gear ratio of the continuously variable transmission, thereby preventing over-rotation of each member of the continuously variable transmission. Is desirable.

  The present invention has been made in view of the above-described circumstances, and prevents a decrease in durability due to over-rotation of a continuously variable transmission by increasing a gear ratio when a gear shifting actuator of the continuously variable transmission fails. Objective.

  To achieve the above object, according to the first aspect of the present invention, an input shaft connected to a drive source, an output shaft connected to a drive wheel, and a disk that rotates integrally with the input shaft. An eccentric disk, a swing arm supported to be swingable on the output shaft via a one-way clutch, a connecting rod that reciprocates by connecting the eccentric disk and the swing arm, and an input shaft A continuously variable transmission including an eccentric amount variable mechanism that changes an eccentric amount of the eccentric disk with respect to an axis, wherein the eccentric amount variable mechanism is arranged coaxially with the input shaft and is rotated by an actuator; A circular eccentric cam fixed to the outer periphery of the input shaft in an eccentric state; a notch formed in the eccentric cam around the axis of the input shaft and opened to the outer peripheral surface of the eccentric cam; and the transmission shaft A pinion that is provided and fits into the notch, and a ring gear that is formed in an eccentric state with the eccentric disc and meshes with the pinion through the notch, and the center of gravity of the eccentric disc is in a top drive state. A continuously variable transmission is proposed, which is located on the underarc side of the outer circumference of the eccentric disk with respect to the secant connecting the axis of the input shaft and the center of the eccentric cam.

  According to the configuration of claim 1, the continuously variable transmission includes an input shaft connected to the drive source, an output shaft connected to the drive wheel, a disc-shaped eccentric disk that rotates integrally with the input shaft, A swing arm supported swingably on the output shaft via a one-way clutch, a connecting rod that reciprocates by connecting the eccentric disk and the swing arm, and an eccentric amount of the eccentric disk with respect to the axis of the input shaft is changed. Equipped with a variable eccentricity mechanism, when the input shaft is rotated by the drive source, the eccentric disk rotates eccentrically with the input shaft and the connecting rod reciprocates, and when the swing arm reciprocates by the reciprocating connecting rod, the one-way clutch Are intermittently engaged, whereby the output shaft rotates intermittently to drive the drive wheels. When the eccentric amount of the eccentric disk with respect to the axis of the input shaft is changed by the eccentric amount variable mechanism, the stroke of the reciprocating motion of the connecting rod changes and the stroke of the reciprocating swing of the swing arm changes. The gear ratio between them is changed steplessly.

  The variable eccentricity mechanism is a transmission shaft that is arranged coaxially with the input shaft and rotated by an actuator, a disc-shaped eccentric cam fixed in an eccentric state on the outer periphery of the input shaft, and the axis of the input shaft in the eccentric cam. A notch that is formed as an opening on the outer peripheral surface of the eccentric cam, a pinion that is provided on the transmission shaft and that fits into the notch, and a ring gear that is formed eccentrically on the eccentric disk and meshes with the pinion through the notch Therefore, when the output shaft is rotated relative to the input shaft by the actuator, the eccentric disk whose ring gear is driven by the pinion rotates around the eccentric cam, thereby changing the eccentric amount of the eccentric disk with respect to the axis of the input shaft. To do.

  When the eccentric disk rotates around the axis of the input shaft, the eccentric disk tries to rotate around the eccentric cam by centrifugal force acting on the center of gravity of the eccentric disk, so the gear ratio is the top drive and the rotational speed of the drive source is If the actuator fails in a high state, the eccentric disk rotates relative to the eccentric cam due to centrifugal force and the gear ratio decreases, and over-rotation can adversely affect the durability of the continuously variable transmission. There is sex.

  However, according to the present invention, the center of gravity of the eccentric disk is such that the axis of the input shaft and the center of the eccentric cam when the transmission gear ratio is in the top drive state are inferior arc side of the outer peripheral circle of the eccentric disk. Therefore, when the actuator fails and the eccentric disk rotates relative to the eccentric cam due to centrifugal force, the eccentric disk rotates relative to the direction in which the gear ratio increases, preventing the continuously variable transmission from over-rotating. Durability is ensured.

The figure which shows the whole structure of a continuously variable transmission. Explanatory drawing of the structure of eccentric amount variable mechanism. Explanatory drawing of the gear ratio change by an eccentricity variable mechanism. Action | operation explanatory drawing of the eccentric amount variable mechanism at the time of failure of an actuator. The figure which shows the other example of the position of the gravity center of an eccentric disk.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the continuously variable transmission T includes an input shaft 11 connected to a drive source E made of, for example, an engine, and an output shaft 12 connected to drive wheels W. An eccentric disk 13 is supported on the input shaft 11 via an eccentricity variable mechanism 14, and the eccentric disk 13 rotates eccentrically with the input shaft 11. The transmission shaft 15 is coaxially arranged inside the hollow input shaft 11. When the transmission shaft 15 is rotated relative to the input shaft 11 by the actuator A, the eccentric amount variable mechanism 14 causes the eccentric disk 13 to move. The amount of eccentricity ε changes and the gear ratio of the continuously variable transmission T is changed.

  A swing arm 17 is pivotally supported on the outer periphery of the output shaft 12 via a one-way clutch 16. The one-way clutch 16 includes an inner member 18 fixed to the outer periphery of the output shaft 12, an outer member 19 fixed to the radially inner end of the swing arm 17, and a plurality of one-way clutches 16 disposed between the inner member 18 and the outer member 19. And 20 springs 21 for urging the rollers 20 in the circumferential direction. A large end portion of a connecting rod 23 is pivotally supported on the outer periphery of the eccentric disk 13 via a bearing 22, and a small end portion of the connecting rod 23 is pivotally supported on a tip end of the swing arm 17 via a pin 24.

  When the eccentric disk 13 rotates eccentrically integrally with the input shaft 11 rotated by the drive source E, the connecting rod 23 pivotally supported at the large end via the bearing 22 on the outer periphery of the eccentric disk 13 reciprocates, and the connecting rod 23 The swing arm 17 pivotally supported by the small end of the shaft through the pin 24 reciprocally swings around the output shaft 12. When the swing arm 17 swings in the direction of arrow a, the one-way clutch 16 is engaged and the driving force is transmitted to the output shaft 12, and when the swing arm 17 swings in the direction of arrow b, the one-way clutch 16 is disengaged. When the transmission of the driving force to the output shaft 12 is interrupted, the output shaft 12 rotates intermittently in the direction of arrow a.

  Therefore, when a plurality of continuously variable transmissions T having the above-described structure are juxtaposed in the axial direction and the eccentric directions of the eccentric disks 13 of the continuously variable transmissions T are shifted from each other, the plurality of continuously variable transmissions T alternately drive force. And the output shaft 12 can be continuously rotated. When the eccentric amount variable mechanism 14 changes the eccentric amount ε of the eccentric disk 13 relative to the input shaft 11 steplessly, the stroke of the reciprocating motion of the connecting rod 23 changes and the stroke of the reciprocating swing of the swing arm 17 changes. Thus, the rotation angle of the output shaft 12 with respect to one stroke of the connecting rod 23 changes, and the transmission ratio between the input shaft 11 and the output shaft 12 is changed steplessly.

  Next, the structure of the eccentricity variable mechanism 14 will be described with reference to FIGS.

  As shown in FIG. 2, the eccentricity variable mechanism 14 includes a disc-shaped eccentric cam 25 formed integrally with the input shaft 11, and the center O1 of the eccentric cam 25 is relative to the axis L of the input shaft 11. Is eccentric by a distance d. A part of the outer periphery of the eccentric cam 25 is opened by a circular notch 25 a centering on the axis L of the input shaft 11. Inside the disc-shaped eccentric disk 13, a ring gear 13 a is formed at a position eccentric from the center O 2 by a distance d, and the ring gear 13 a is slidably supported on the outer periphery of the eccentric cam 25. A pinion 26 formed integrally with the transmission shaft 15 meshes with the ring gear 13 a of the eccentric disk 13 through the notch 25 a of the eccentric cam 25. Therefore, when the transmission shaft 15 rotates relative to the input shaft 11, the eccentric disk 13 driven by the pinion 26 on the ring gear 13 a is guided to the outer periphery of the eccentric cam 25 and rotates relative to the input shaft 11, and the input shaft 11 is eccentric relative to the axis L. The amount of eccentricity ε of the center O2 of the disk 13 changes.

  FIG. 3A shows a state where the gear ratio is minimum (overdrive: OD). At this time, the eccentric amount ε of the center O2 of the eccentric disk 13 with respect to the axis L of the input shaft 11 is the axis L of the input shaft 11. To a center O1 of the eccentric cam 25 and a maximum value equal to 2d which is the sum of the distance d from the center O1 of the eccentric cam 25 to the center O2 of the eccentric disk 13. When the transmission shaft 15 rotates relative to the input shaft 11, the eccentric disk 13 rotates relative to the eccentric cam 25 integral with the input shaft 11, as shown in FIGS. 3B and 3C. Furthermore, the amount of eccentricity ε of the center O2 of the eccentric disk 13 with respect to the axis L of the input shaft 11 gradually decreases from the maximum value 2d, and the gear ratio increases. When the transmission shaft 15 further rotates relative to the input shaft 11, the eccentric disk 13 further rotates relative to the eccentric cam 25 integral with the input shaft 11, and finally, as shown in FIG. The center O2 of the eccentric disk 13 overlaps the axis L of the input shaft 11, the eccentricity ε becomes zero, the transmission gear ratio becomes maximum (infinite) (geared neutral: GN), and power is transmitted to the output shaft 12. Is cut off.

  Returning to FIG. 2, a crescent-shaped thin portion 13 b whose thickness is thinner than other portions is formed in a portion of the eccentric disc 13 far from the center O <b> 1 of the eccentric cam 31. The position of the center of gravity G is adjusted as follows.

  The position of the eccentric disk 13 in FIG. 2 corresponds to the state where the gear ratio is top drive: TD. The top drive is a gear ratio that provides the maximum vehicle speed. At this time, the rotational speed of the drive source E becomes the upper limit rotational speed (for example, 6000 rpm). In this top drive state, when a straight line (secant line S) connecting the axis L of the input shaft 11 and the center O1 of the eccentric cam 31 is drawn, the secant line S intersects with the outer circumference circle of the eccentric disk 13 so that the outer circumference circle is long. It is divided into a major arc Ama on the side and a minor arc Ami on the short side. The position of the center of gravity G of the eccentric disk 13 is set in a hatched area on the side of the subarc Ami from the secant line S.

  The position of the center of gravity G of the eccentric disk 13 does not necessarily have to be on the eccentric disk 13, and may protrude beyond the eccentric disk 13. However, for this purpose, it is necessary to provide a weight so as to protrude outward from the outer periphery of the eccentric disk 13. Further, in order to adjust the position of the center of gravity G, a hole is formed so as to penetrate the eccentric disk 13, a weight is embedded in the eccentric disk 13, or a plurality of members having different specific gravities are coupled to the eccentric disk 13. It is conceivable to configure it.

  In FIG. 2, the straight line connecting the center O1 of the eccentric cam 31 and the center O2 of the eccentric disk 13 happens to be orthogonal to the dividing line S. However, the gear ratio (the amount of eccentricity ε) in the top drive state differs depending on the vehicle. The two straight lines are not necessarily orthogonal to each other.

  Next, the operation of the embodiment of the present invention having the above configuration will be described.

  FIGS. 4C and 4D show a comparative example in which the position of the center of gravity G of the eccentric disk 13 is present on the dominant arc Ama side of the secant line S. FIG. In this comparative example, as shown in FIG. 4C, when the vehicle is traveling at the speed ratio of the top drive, the axis G of the input shaft 11 is located at the center of gravity G of the eccentric disk 13 rotating around the input shaft 11. Centrifugal force F <b> 1 that extends radially outward through L acts. A reaction force F2 having the same magnitude as the centrifugal force F1 and acting in the opposite direction acts on the center O1 of the eccentric cam 25 that supports the eccentric disk 13, and the centrifugal force F1 and the reaction force F2 are balanced. When the distance between the line of action of the centrifugal force F1 and the center O1 of the eccentric cam 31 is a, a moment M = F1 × a that acts to rotate the eccentric disk 13 clockwise around the center O1 of the eccentric cam 31 acts. However, this moment M is supported by the actuator A as the holding torque of the pinion 32, so that the eccentric disk 13 is prevented from rotating and the gear ratio is maintained in the top drive state.

  However, if the actuator A fails for some reason and the holding torque of the pinion 32 disappears, the eccentric disk 13 rotates clockwise around the eccentric cam 31 due to the moment M, and as shown in FIG. Changes to the overdrive side. Normally, the rotational speed of the drive source E when the speed ratio is overdrive is 2000 to 3000 rpm, but when the speed ratio is the top drive, the drive source E may reach the speed of 6000 rpm, so the speed ratio is When the top drive state is changed to the overdrive side, the connecting rod 23 and the one-way clutch 16 cannot endure, and the durability of the continuously variable transmission T may be reduced.

  On the other hand, as shown in FIG. 4A, according to the present embodiment, since the position of the center of gravity G of the eccentric disk 13 is located on the side of the subarc Ami from the secant line S, the center of gravity G of the eccentric disk 13 The counterclockwise moment M = F1 × a acts by the acting centrifugal force F1. As a result, when the actuator A fails and the holding torque of the pinion 32 disappears, the eccentric disk 13 is rotated counterclockwise around the eccentric cam 31 by the moment M, and the speed change is performed as shown in FIG. The ratio changes from the top drive state to the geared neutral side. Therefore, even if the drive source E rotates at the maximum rotation speed, each member of the continuously variable transmission T is prevented from over-rotating, and durability is ensured.

  When the position of the center of gravity G of the eccentric disk 13 is on the secant line S, the moment M due to the centrifugal force F1 does not act on the eccentric disk 13, so that the gear ratio is theoretically in the top drive state when the actuator A fails. However, the position of the center of gravity G of the eccentric disk 13 is located on the underarc Ami side of the secant line S because there is a possibility that it may change to either the overdrive side or the geared neutral side due to disturbance. It is necessary to.

  By the way, the magnitude of the centrifugal force acting on the center of gravity G of the eccentric disk 13 is the distance between the axis L of the input shaft 11 that is the center of rotation of the eccentric disk 13 and the center of gravity G, that is, the rotation radius R of the center of gravity G (FIG. 5 ( In order to ensure a sufficient moment M for rotating the eccentric disk 13, it is necessary to set the rotation radius R large. Since the eccentric disk 13 has a large area on the superior arc Ama side of the dividing line S and a small area on the inferior arc Ami side of the dividing line S, the thin-walled portion 13b is used to position the center of gravity G on the minor arc Ami side of the dividing line S. It is necessary to take measures such as increasing the size or providing a weight 27 on the side of the subarc Ami as shown in FIG.

  As shown in FIG. 5A, if the center of gravity of the eccentric disk 13 is set at the position G ′, not only the rotation radius R of the center of gravity G ′ is reduced, but also a large thin portion 13b and a heavy weight 27 are required. As a result, there is a problem that the degree of freedom in design is reduced. On the other hand, when the center of gravity of the eccentric disk 13 is set to G that is close to the dividing line S and far from the axis L of the input shaft 11, a large thin portion 13b and a heavy weight 27 are not required while ensuring a large rotation radius R. The degree of freedom can be increased. In order to set the center of gravity at the position G in FIG. 5A, the thin portion 13b of the eccentric disk 13 may be provided only on the lower side in the drawing, and the weight may be provided on the upper side in the drawing of the subarc Ami.

  The rotation angle at which the eccentric disk 13 rotates toward the geared neutral side when the actuator A fails is divided into a secant line S extending upward from the center O1 of the eccentric cam 25 and a straight line extending from the center O1 of the eccentric cam 25 to the center of gravity G. It corresponds to the formed angle α. In the example of FIG. 5A, since the angle α is small, the rotation angle of the eccentric disk 13 when the actuator A fails is small. However, as shown in FIG. 5B, the eccentric disk 13 is counterclockwise. Since it rotates and the gear ratio increases from the top drive state to the geared neutral state, each member of the continuously variable transmission T is prevented from over-rotating.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the drive source of the present invention is not limited to the engine of the embodiment, and may be another type of drive source such as an electric motor.

A Actuator Ami Inferior arc E Drive source ε Eccentric amount G of eccentric disc G Center of gravity L of eccentric disc Input shaft axis O1 Center of eccentric cam S Split line W Drive wheel 11 Input shaft 12 Output shaft 13 Eccentric disc 13a Ring gear 14 Eccentric amount variable mechanism 15 Transmission shaft 16 One-way clutch 17 Swing arm 23 Connecting rod 25 Eccentric cam 25a Notch 26 Pinion

Claims (1)

An input shaft (11) connected to the drive source (E), an output shaft (12) connected to the drive wheels (W), and a disc-shaped eccentric disk (which rotates integrally with the input shaft (11)) 13), a swing arm (17) supported swingably on the output shaft (12) via a one-way clutch (16), the eccentric disk (13) and the swing arm (17). And a connecting rod (23) that reciprocates and an eccentricity variable mechanism (14) that changes the eccentricity (ε) of the eccentric disk (13) with respect to the axis (L) of the input shaft (11). A step transmission,
The variable eccentricity mechanism (14) is coaxially arranged with the input shaft (11) and is fixed to the transmission shaft (15) rotated by the actuator (A) and the outer periphery of the input shaft (11) in an eccentric state. A disc-shaped eccentric cam (25), and a notch formed in the eccentric cam (25) about the axis (L) of the input shaft (11) and opened to the outer peripheral surface of the eccentric cam (25) (25a), a pinion (26) provided on the transmission shaft (15) and fitted in the notch (25a), and the eccentric disk (13) formed in an eccentric state and the notch (25a). A ring gear (13a) meshing with the pinion (26) through,
The center of gravity (G) of the eccentric disk (13) is a secant line connecting the axis (L) of the input shaft (11) and the center (O1) of the eccentric cam (25) when the gear ratio is in the top drive state. A continuously variable transmission characterized in that it is located on the underarc (Ami) side of the outer circumference of the eccentric disk (13) with respect to S).

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