JP4437413B2 - Forward / reverse switching device - Google Patents

Description

The present invention relates to a forward / reverse switching device for use in an automobile transmission or the like.

2. Description of the Related Art Conventionally, a forward / reverse switching device is provided in an automotive transmission such as a continuously variable transmission, and Patent Document 1 proposes a forward / reverse switching device that is small and can be smoothly switched.
Patent Document 2 discloses a specific structure thereof.
FIG. 5 shows a forward / reverse switching device disclosed in Patent Document 2. 60 is a rotating shaft, 61 is a forward gear, 62 is a reverse gear, 63 is a hub disposed at an intermediate position, and 64 is forward / backward switching. A sleeve 65 is a power intermittent clutch composed of a wet multi-plate clutch. A clutch hub 66 of the clutch 65 is rotatably supported on the rotary shaft 60, and a reverse gear 62 is rotatably supported on the clutch hub 66. An outer spline is provided at the tip of the clutch hub 66, and a hub 63 is spline-fitted to the outer spline, and the clutch hub 66 and the hub 63 are connected so as to be integrally rotatable.

At the time of forward / reverse switching, the hub 63 and the forward gear 61 or the reverse gear are shifted by axially shifting the sleeve 64 that is spline-fitted to the hub 63 with the clutch 65 disengaged and the transmission of power cut off. Any one of 62 is connected.

However, due to the drag torque of the clutch 65, the sleeve 64 rotates even in the neutral (N) state, and when the sleeve 64 is shifted from the neutral state (N) to the forward (F) or reverse (R), the forward gear 61 or the reverse gear In some cases, the gear spline of the gear 62 does not mesh well. In particular, it tends to occur when the oil viscosity is high, such as when it is cold. Further, in the process in which the sleeve 64 meshes with the gear spline, the teeth of the rotating sleeve 64 collide with the stopped gear spline, and noise is generated between them, and tooth surface wear (sagging) occurs. There was a problem that occurred.
JP-A-62-4941 JP-A-62-220755

Therefore, an object of the present invention is to provide a forward / reverse switching device that can smoothly shift to a forward position or a backward position by braking a sleeve in a neutral state.

In order to achieve the above object, the invention according to claim 1 is arranged at an intermediate position between the forward gear and the reverse gear, which are rotatably arranged on the rotation shaft, and the forward gear and the reverse gear. An intermediate hub, a forward / reverse switching sleeve that selectively connects one of the forward gear and the reverse gear to the intermediate hub, and a claw portion that engages with an outer peripheral groove of the sleeve; And a forward / reverse switching device comprising a fork that shifts in the axial direction to each of the reverse positions and a power interrupting clutch provided on the rotating shaft, wherein the clutch hub of the power interrupting clutch is on the rotating shaft. It is rotatably arranged and is connected to the intermediate hub so as to be integrally rotatable, the fork is provided so as to be rotatable about a fork shaft, and the claw portion of the fork is connected to the outer circumferential groove of the sleeve. The fork is pivotally urged in a direction to press the surface, to generate a frictional force against the pawl portion of the fork to the bottom of the circumferential groove of the sleeve, provided with means for braking the rotation movement of the sleeve, It is an object of the present invention to provide a forward / reverse switching device characterized in that the braking means generates a larger frictional force when the fork is in the neutral position than when the fork is in any other position .

If the sleeve rotates due to clutch drag torque or the like in the neutral position, it may not mesh well with the gear spline when the sleeve is shifted from the neutral state to the forward or backward position. Therefore, the rotation of the sleeve is stopped by pressing the claw portion of the fork at the neutral position against the bottom surface of the outer peripheral groove of the sleeve and braking. As a result, the sleeve can smoothly mesh with the gear spline of the forward gear or the reverse gear. In addition, since both the sleeve and the gear spline are stopped in the process in which the sleeve and the gear spline are engaged with each other, there is no problem that abnormal noise is generated or wear is generated between them.
If the sleeve is braked too much, the sleeve cannot rotate when the chamfer of the sleeve meshes with the gear spline of the forward gear or the reverse gear, and the smooth meshing performance may be impaired. However, since the claw portion of the fork only presses against the bottom surface of the outer peripheral groove of the sleeve to generate frictional resistance, the sleeve can be allowed to rotate and the meshing performance is not impaired.
Further, since the braking means hardly works at the time of forward movement or backward movement, it is possible to suppress the occurrence of wear between the fork and the sleeve.

According to a second aspect of the present invention, the braking means includes a lock ball provided on a fixing member such as a housing so as to be movable in a direction facing the outer peripheral surface of the fork, and a biasing means for biasing the lock ball in the fork direction. A contact surface formed on an outer peripheral surface corresponding to the claw portion of the fork and contacting with the lock ball, and a mountain portion formed on the contact surface on which the lock ball rides in the neutral position. It is good also as a structure which presses the nail | claw part of a fork to the bottom face of the outer periphery groove | channel of a sleeve when getting over .
In this case, since the lock ball presses the fork from the back and presses the claw portion against the bottom surface of the outer peripheral groove of the sleeve, the braking action can be reliably exerted on the sleeve. Further, since the lock ball can roll while shifting from the forward position to the neutral position to the reverse position, wear on the contact surface and the ridges can be reduced.
In addition, although a contact surface and a peak part can also be formed integrally with a fork, there is a possibility of wearing due to contact with a lock ball. Therefore, if the guide plate made of a metal plate having excellent wear resistance is fixed to the outer periphery of the fork and the contact surface and the crest are formed on the guide plate, the problem of fork wear can be solved.

According to the present invention, the claw portion of the fork in the neutral position is pressed against the bottom surface of the outer peripheral groove of the sleeve and braking is performed to stop the rotation of the sleeve, so that the sleeve can be a forward gear or a reverse gear. The spline can be smoothly meshed with each other, and the shift-in performance can be improved. In addition, there is no problem that abnormal noise or wear occurs between the sleeve and the gear spline in the process of engagement between the sleeve and the gear spline.

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

FIG. 1 shows a skeleton structure of an example of a continuously variable transmission for a vehicle using a forward / reverse switching device according to the present invention.
The continuously variable transmission of this embodiment is an FF horizontal type, which is roughly an input shaft 3 driven by the engine output shaft 1 through the torsional damper 2, a drive shaft 10 that supports the drive pulley 11, and a driven pulley 21. A driven shaft 20 that supports the drive pulley 11, a dry V belt 15 wound around the drive pulley 11 and the driven pulley 21, a forward / reverse switching device 24, a starting clutch 30, a first reduction shaft 40, a second reduction shaft 41, and a wheel. The output shaft 42, a speed change motor 45, a tensioner device (not shown), and the like are included. The input shaft 3, the drive shaft 10, the driven shaft 20, the first reduction shaft 40, the second reduction shaft 41, and the output shaft 42 are all non-coaxial and arranged in parallel.
The V-belt 15 used in this embodiment is a well-known composite belt composed of a pair of endless tension bands and a number of blocks locked in the length direction by these tension bands.

The input shaft 3 is integrally formed with an input gear 3 a that meshes with a gear 10 a provided at the engine side end of the drive shaft 10. By appropriately setting the reduction ratio between the input gear 3a and the gear 10a, the drive shaft 10 can be rotated at a reduction ratio suitable for belt driving.

The drive pulley 11 includes a fixed sheave 11a fixed on the drive shaft 10, a movable sheave 11b supported on the drive shaft 10 so as to be movable in the axial direction, and a stroke mechanism 12 provided behind the movable sheave 11b. The movable sheave 11b and the stroke mechanism 12 are disposed closer to the engine than the V belt 15. The stroke mechanism 12 of this embodiment is a ball screw mechanism that moves the movable sheave 11b in the axial direction by rotational input from the speed change motor 45, and is a female screw member 12b that is supported on the movable sheave 11b via a bearing 12a so as to be relatively rotatable. And a male screw member 12c fixed to the transmission case, and a transmission gear 13 is fixed to the outer periphery of the female screw member 12b.

The driven pulley 21 includes a fixed sheave 21a fixed on the driven shaft 20, a movable sheave 21b supported on the driven shaft 20 so as to be axially movable, and a stroke mechanism 22 provided behind the movable sheave 21b. The movable sheave 21b and the stroke mechanism 22 are disposed on the opposite side of the engine from the V belt 15. The stroke mechanism 22 is also a ball screw mechanism having the same configuration as the stroke mechanism 12 of the drive pulley 11, and is fixed to the transmission case and a female screw member 22 b that is relatively rotatably supported by a movable sheave 21 b via a bearing 22 a. The transmission gear 23 is fixed to the outer peripheral portion of the female screw member 22b.

A forward / reverse switching device 24 is provided at a position closer to the engine than the driven pulley 21 of the driven shaft 20. As shown in FIG. 2, the forward / reverse switching device 24 includes a forward gear 25, a reverse gear 26, a hub 27 disposed at an intermediate position between both gears, and a front / rear gear that selectively connects one of the two gears to the hub 27. An advance switching sleeve 28 and the like are provided. When the sleeve 28 is in the intermediate position as shown in the upper half of FIG. 2, the neutral (N) position is set. When the sleeve 28 is shifted to the left, the forward (F) position is obtained.

The forward gear 25 is rotatably supported on the driven shaft 20, and the reverse gear 26 is rotatably supported on a clutch hub 31 of a starting clutch 30 described later. The clutch hub 31 is spline-fitted with the hub 27, and the hub 27 and the clutch hub 31 rotate integrally.

An outer peripheral groove 28a is formed on the outer periphery of the sleeve 28 of the forward / reverse switching device 24, and the claws 50a and 50b of the fork 50 shown in FIG. 3 are engaged with the outer peripheral groove 28a. The fork 50 is formed with a shifting claw portion 50a for shifting the sleeve 28 in the axial direction and a braking claw portion 50b for pressing the bottom surface of the outer peripheral groove 28a of the sleeve 28. The outer peripheral portion of the fork 50 corresponding to the braking claw portion 50b is formed wide, and a concave groove 50c extending in the axial direction is formed on the outer periphery of the wide portion, and the guide plate 51 is fitted into the concave groove 50c. Has been. The guide plate 51 is formed by bending a single sheet metal as shown in FIG. 4, and is preferably formed of a metal material having excellent wear resistance. The guide plate 51 is formed with a pair of attachment pieces 51a that protrudes on both sides. The attachment pieces 51a are fixed to the fork 50 by fastening the attachment pieces 51a to the side surfaces of the fork 50 with bolts 52 (see FIG. 2). . Reference numeral 50 d denotes a screw hole for fastening the boulder 52. The guide plate 51 is formed with a guide groove 51b extending in the shift direction (axial direction) which is a contact surface, and a crest 51c at a center portion of the guide groove 51b, that is, a position corresponding to the neutral position.

On the other hand, the housing 6 that is a transmission case is formed with a through hole 6a extending in a direction opposite to the outer peripheral surface of the fork 50, and a lock ball 53 is inserted into the through hole 6a. A spring 54 for urging in the direction of the plate 51 is inserted. The lock ball 53 and the spring 54 are prevented from coming off by screwing the presser bolt 55 into the through hole 6a. The lock ball 53 is always in contact with the guide plate 51, contacts the bottom surface of the guide groove 51b at the forward and backward positions, and rides on the mountain 51c at the neutral position. Therefore, in the neutral position, the repulsive force of the spring 54 acts on the guide plate 51 via the lock ball 53, and further urges the fork 50 to rotate in the direction of arrow A in FIG. As a result, the braking claw portion 50b of the fork 50 comes into pressure contact with the bottom surface of the outer peripheral groove 28a of the sleeve 28, and the sleeve 28 can be braked by its frictional resistance. Note that the lock ball 53 is in contact with the bottom surface of the guide groove 51b even in the forward position and the reverse position. However, at this position, the spring force of the spring 54 is low, and the pressure contact between the hooking claw portion 50b and the bottom surface of the outer peripheral groove 28a of the sleeve 28 Power is low. Therefore, almost no frictional resistance is generated.

As described above, the braking claws 50b of the fork 50, the guide plate 51, the lock ball 53, and the spring 54 constitute the braking means 29 that stops the rotation of the sleeve 28 in the neutral position.
In the neutral position, a starting clutch 30 described later is released, but the sleeve 28 may follow and rotate due to the drag torque of the clutch 30. In particular, it tends to occur when the oil viscosity is high, such as when it is cold. If the sleeve 28 is to be shifted from the neutral position (N) to the forward position (F) or the reverse position (R) in this state, the sleeve 28 is rotating, so that the gear spline of the forward gear 25 or the reverse gear 26 May not mesh well. However, since the sleeve 28 is braked by the fork 50 at the neutral position, the rotation of the sleeve 28 can be almost stopped, and the shift-in performance with the gear spline can be improved. Further, since both the sleeve 28 and the gear spline are stopped, no gear collision noise is generated in the meshing process, and there is no wear (sagging) of the tooth surface.

Further, when the fork 50 is in the forward position and the backward position, the lock ball 53 is in contact with the bottom surface of the guide groove 51 b of the guide plate 51. Therefore, the braking means 29 hardly works at the time of forward movement or reverse movement, and the occurrence of wear between the fork 50 and the sleeve 28 can be suppressed. Further, even when a shift force in the gear disconnection direction is applied to the fork 50 by an impact force or the like at the time of forward movement and reverse movement, the gear disconnection can be prevented by the contact between the lock ball 53 and the peak portion 51c.

A starting clutch (power interrupting clutch) 30 is provided at the shaft end of the driven shaft 20 on the engine side. The starting clutch 30 is provided adjacent to and coaxially with the forward / reverse switching device 24, and is disposed upstream of the forward / backward switching device 24 in the power transmission path. The starting clutch 30 has a function of performing slip control at the time of starting, a function of cutting off power transmission between the hub 27 and the driven shaft 20 when neutral, a function of cutting off power transmission between the driven shaft 20 and the output shaft 42 during sudden deceleration, and the like. Have

As shown in FIG. 2, the starting clutch 30 includes a clutch hub 31, a clutch drum 32 that is spline-fitted to the driven shaft 20, a piston 33 that is disposed inside the clutch drum 32, a clutch drum 32, and a clutch hub 31. It is a wet multi-plate clutch provided with a plurality of clutch plates 34 and the like disposed between them.
The reason why the starting clutch 30 is provided on the driven shaft 20 is that the starting clutch 30 is released and the output shaft 42 is driven when the V-belt 15 cannot rapidly return from the High position to the Low position during sudden deceleration. This is to ensure low return performance by cutting off power transmission with the shaft 20.

The forward gear 25 is engaged with the gear 40a of the first reduction shaft 40, the gear 40b of the first reduction shaft 40 is engaged with the gear 41a of the second reduction shaft 41, and the gear 41b of the second reduction shaft 41 is further connected to the differential device 43. Is engaged with the ring gear 43a. Further, the reverse gear 26 meshes with the gear 40 b of the first reduction shaft 40 through the idler gear 44. And the output shaft 42 connected with the wheel via the differential device 43 is driven.

The output gear 46 of the speed change motor 45 is meshed with a reduction gear 47 a provided at one end of the first speed change shaft 47. A gear 47 b provided at the other end of the first transmission shaft 47 is a spur gear having a length corresponding to the moving stroke of the movable sheave 21 b of the driven pulley 21, and meshes with the transmission gear 23 provided on the driven pulley 21. Yes. When the gear 47b of the first speed change shaft 47 is rotated, the speed change gear 23 is rotated to move the movable sheave 21b in the axial direction by the action of the ball screw mechanism 22. That is, the pulley groove width (belt winding diameter) of the driven pulley 21 can be continuously changed by the speed change motor 45.

The transmission gear 23 of the driven pulley 21 meshes with the first idler gear 48 a of the second transmission shaft 48, and the second idler gear 48 b of the second transmission shaft 48 meshes with the transmission gear 13 of the drive pulley 11. The idler gears 48a and 48b are also constituted by spur gears having a length corresponding to the moving stroke of the movable sheaves 11b and 21b, like the gear 47b of the first transmission shaft 47. The rotational force of the speed change motor 45 is transmitted to the speed change gear 13 of the drive pulley 11 via the first speed change shaft 47, the speed change gear 23 of the driven pulley 21, and the second speed change shaft 48. Therefore, the movable sheave 11a of the driving pulley 11 and the movable sheave 21a of the driven pulley 21 are synchronized with each other, and can move in the axial direction while changing the pulley groove width (belt winding diameter) in the opposite direction.

As described above, the pulley groove width (belt wrapping diameter) of the pulleys 11 and 21 is varied in the opposite direction by the speed change motor 45. However, the slippage between the V belt 15 and the pulleys 11 and 21 is caused by the transmission torque. Will occur. Therefore, a tensioner device is provided in order to give the belt tension sufficient to prevent the V belt 15 from slipping. This tensioner device includes a tension roller that presses the loose side of the V-belt 15 inward, and this tension roller is supported by a swingable tensioner arm. Since the specific structure of the tensioner device is known, for example, from Japanese Patent No. 3267596, Japanese Patent No. 3290647, etc., description thereof is omitted here.

The present invention is not limited to the above embodiments.
In the above embodiment, the example in which the guide plate is fixed to the fork has been described. However, the contact surface with the lock ball and the peak portion may be integrally formed on the outer periphery of the fork. In this case, the number of parts can be reduced.
In addition, a lock ball and a spring are used to apply a rotational biasing force to the fork. For example, a leaf spring is fixed to the inner surface of the housing, and a mountain is formed on the outer periphery of the fork that contacts the leaf spring in the neutral position. An urging force may be applied by providing the portion. In this case, it is not necessary to provide a guide groove in the fork.
In the above-described embodiment, an example in which the forward / reverse switching device of the present invention is applied to a continuously variable transmission has been described, but it is needless to say that the present invention can also be applied to a general automatic transmission or manual transmission.
Further, the forward / reverse switching device is not limited to being provided on the driven shaft, but may be provided on the drive shaft.
Although the power intermittent clutch (wet multi-plate clutch) is provided adjacent to and coaxially with the forward / reverse switching device, it is not limited to this, and it should be disposed at least upstream of the power transmission path from the forward / reverse switching device. That's fine.

It is a skeleton diagram of an example of a continuously variable transmission to which a forward / reverse switching device according to the present invention is applied. It is sectional drawing of the forward / reverse switching apparatus shown in FIG. FIG. 3 is a side view of the fork shown in FIG. 2. It is a perspective view of a guide plate. It is sectional drawing of the conventional forward / reverse switching apparatus.

Explanation of symbols

20 Driven shaft (Rotating shaft)
24 Forward / reverse switching device 25 Forward gear 26 Reverse gear 27 Hub 28 Sleeve 28a Outer peripheral groove 29 Breaking means 30 Starting clutch (power intermittent clutch)
50 Fork 50b Claw 51 Guide plate 51b Guide groove (contact surface)
51c Mountain part 53 Rock ball 54 Spring

Claims (2)

One of the forward gear and the reverse gear is intermediate between the forward gear and the reverse gear that are rotatably arranged on the rotation shaft, the intermediate hub that is disposed at an intermediate position between the forward gear and the reverse gear, and the forward gear. A forward / reverse switching sleeve selectively connected to the hub, a fork having a claw portion engaged with an outer circumferential groove of the sleeve, and for axially shifting the sleeve to forward, neutral and backward positions, and the rotation In a forward / reverse switching device provided with a power interrupting clutch provided on a shaft,
The clutch hub of the power interrupting clutch is rotatably arranged on the rotating shaft and is connected to the intermediate hub so as to be integrally rotatable.
The fork is provided so as to be rotatable around a fork shaft,
The fork is rotated and biased in a direction to press the claw portion of the fork against the bottom surface of the outer peripheral groove of the sleeve, and the claw portion of the fork is pressed against the bottom surface of the outer peripheral groove of the sleeve to generate a frictional force. Providing means to brake the movement in the direction ,
The forward / reverse switching device characterized in that the braking means generates a larger frictional force when the fork is in the neutral position than when the fork is in any other position . The braking means is
A lock ball provided on a fixing member such as a housing so as to be movable in a direction facing the outer peripheral surface of the fork;
Biasing means for biasing the lock ball in the fork direction;
A contact surface formed on an outer peripheral surface corresponding to the claw portion of the fork, and the lock ball contacts;
A mountain portion formed on the contact surface and on which the lock ball rides in a neutral position,
The forward / reverse switching device according to claim 1, wherein when the lock ball gets over the mountain portion, the claw portion of the fork is pressed against the bottom surface of the outer peripheral groove of the sleeve.

Images