JPH0742807A - Bidirectional differential clutch of continuous transmission - Google Patents

Abstract

PURPOSE:To provide a continuously variable transmission equipped with a belt tension mechanism which utilizes the cam surfaces of a torque cam and hub, with which changing-over of advancing and reversing of a bidirectional differential clutch regardless of a play not admitting contact of the cam surface. CONSTITUTION:A continuously variable transmission is equipped with a bidirectional differential clutch CL, whose difference in the number of cogs between the input gear and a sub-gear is made greater. and thereby the rotating angle of a drive shaft DS required for a sprag to be clamped is set smaller than the play angle between the cam surfaces 20a, 21a of a torque cam 20 and hub 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-way differential clutch in a continuously variable transmission.

[0002]

2. Description of the Related Art A schematic structure of a conventional continuously variable transmission will be described with reference to FIG. 1. The rotation of a drive shaft DS on the engine ENG side is transmitted to an input shaft IS, and the rotation of the input shaft IS is transmitted to the input shaft IS. By the belt V mounted between the pair of separable input-side pulleys IP1 and IP2 attached to the shaft IS and the pair of separable output-side pulleys OP1 and OP2 attached to the output shaft OS. , Are transmitted to the output shaft OS without any change in speed, and are further transmitted to the drive wheels W. Further, as a power transmission path, in addition to the main power transmission path via the belt V, an auxiliary power transmission path for transmitting to the output shaft OS via a two-way differential clutch CL is provided. The two-way differential clutch CL is shown in FIG.
The structure is shown in FIG. 3, which is a sectional view taken along the line AA of FIG. 2, FIG. 4 and FIG. 5 are operation explanatory views, and FIG. In FIG. 2, reference numeral 1 denotes a rotary shaft, which has various stepped portions on the outer peripheral surface. An output gear 4 is connected to one step of the rotary shaft 1 by a spline 4b. Reference numeral 4a is a tooth provided on the outer periphery of the output gear 4 and meshes with a gear (not shown) on the output shaft OS side. 1
An outer peripheral cylindrical surface 7 is formed in parallel with the input gear 2 at another step portion on the outer periphery of the rotary shaft 1. The input gear 2 has an inner peripheral cylindrical surface 18, and is externally inserted with a gap on the outer peripheral cylindrical surface 17. 2b is the input gear 2
The teeth formed on the outer periphery of the gear mesh with a gear (not shown) on the drive shaft DS side.

As can be seen from the enlarged view of the main part of FIG. 6, a plurality of sprags 6 are circumferentially arranged at predetermined intervals between the inner peripheral cylindrical surface 18 of the input gear 2 and the outer peripheral cylindrical surface 17 of the rotary shaft 1. It is arranged. Cylindrical surface 1 facing this sprag 6
In a neutral state in which the sprag 6 stands upright, the inner diameter side arcuate surface 6a and the outer diameter side arcuate surface 6b of the sprag 6 and the cylindrical surface 1 are formed.
A radial skimmer is formed between 7 and 18. When the sprag 6 falls down in the circumferential direction of the cylindrical surfaces 17 and 18 from the neutral state, the inner diameter side arc surface 6a and the outer diameter side arc surface 6b engage with the opposing cylindrical surfaces 17 and 18. The outer diameter side end portion of the sprag 6 is fitted into the pocket 9a of the outer holding member 9 fixed to the inner circumferential cylindrical surface 18 of the input gear 2 by a method such as press fitting, and the inner diameter side end portion is fitted into the outer holding member 9. It is fitted in a pocket 10a of an inner holding member 10 which is slidably inserted between the rotary shaft 1 and the input gear 2. The dimension between the side surfaces of the outer holding member 9 that face each other in the circumferential direction of the pocket 9a is smaller than the dimension of the side surfaces of the inner holding member 10 that face each other in the circumferential direction.
A recess 10b is formed in the center of the side surfaces of the inner holding member 10 that face each other in the circumferential direction of the pocket 10a, and the pair of elastic bodies 7 incorporated in the recess 10b allow the inner ends of the sprags 6 from both sides. By pressing, the sprag 6 is held in a neutral state as shown in FIG. Here, a leaf spring, a Koly spring, or the like can be used as the elastic body 7. In the figure, H is a hole for discharging iron powder or the like.

Returning to FIG. 2, reference numeral 8 is a sub gear, which is arranged in parallel with the input gear 2. Reference numeral 8a is a tooth provided on the outer periphery of the sub gear 8 and, like the input gear 2, has a drive shaft D.
It meshes with the gear on the S side. The inner holding member 10 is slidably inserted into the inner circumference of the input gear 2 on the inner circumference side of the sub gear 8. The sub gear 8 is pressed by a disc spring 19 between the retaining ring 20 attached to the inner holding member 10 and the side surface of the step portion of the inner holding member 10. A part of the outer holding member 9 is cut out on the inner peripheral side to form a notch 11, while the inner holding member 10 is provided with a stopper 1 a at a position facing the notch 11. Reference numerals 12 and 14 denote bearings for supporting the rotary shaft 1, and 13 denotes the input gear 2.
Reference numeral 5 is a bearing that supports the inner holding member 10.

The operation of the two-way differential clutch constructed as described above will be described. The rotation of the gear on the drive shaft DS side is transmitted to the input gear 2 and the sub gear 8 meshing with the rotation of the gear. However, the teeth 2b of the input gear 2 are
For example, while the number of teeth is 53, the teeth 8a of the sub gear 8 are
Has, for example, the number of teeth set to 54, and the same drive axis D
Due to the rotation of S, the rotation of the sub gear 8 lags behind the rotation of the input gear 2. Therefore, as shown in FIG. 5, the inner holding member 10 pressed against the sub gear 8 is pressed.
Has a differential speed with respect to the rotation of the input gear 2 and relatively rotates until the stopper 1a comes into contact with the end surface of the notch 11 of the outer holding member 9. The sprag 6 housed in the pocket 10a of the inner holding member 10 is the inner holding member 1
It falls in the direction of 0 rotation. Therefore, as shown in FIG.
The inner diameter side arcuate surface 6a and the outer diameter side arcuate surface 6b of the sprag 6 engage with the opposing cylindrical surfaces 17 and 18, and the clutch can be operated, that is, the sprag can be clamped.

Here, when the vehicle is running at high speed,
Since the rotation of the output gear 4, that is, the rotation shaft 1 is set to rotate faster than the rotation of the input gear 2, the sprag 6 receives a frictional force in the standing direction and spins idle.
It does not bite into the cylindrical surfaces 17 and 18. In contrast,
When the vehicle is in a starting state, the rotation of the input gear 2 is set to be faster than the rotation of the output gear 4, that is, the rotation shaft 1, and the clutch is actuated to rotate the rotation force of the input gear 2 to the rotation shaft 1. Will be transmitted to.
After the stopper 1a contacts the wall surface of the notch 11, the inner holding member 10 idles with respect to the sub gear 8, so that the sub gear 8 is not damaged. As described above, the clutch operating principle of the sprag 6 due to the differential speed of the sub gear 8 is not related to the rotation direction of the input gear 2, so that the two-way differential clutch functions effectively even when the vehicle is moving in reverse. It is configured.

Further, the structure of the output side pulleys OP1 and OP2 moves along the output shaft OS so as to face the fixed output side pulley OP1 integrally provided on the output shaft OS as shown in the sectional view of FIG. A movable output side pulley OP2 is provided so that the movable output side pulley OP2 is movable.
Is provided with a belt tension mechanism for applying tension to the belt V. With this belt tension mechanism,
In order to apply tension to the belt V, a torque cam 20 is fixed or formed integrally with the pulley OP2 on the outer surface of the back side of the movable output side pulley OP2.
On the cam surface 20a having the wedge angle α at the right end of 0, the output shaft O
The corresponding cam surface 21a of the hub 21 fixed to S is brought into contact, and a perspective view of the torque cam 20 and the hub 21 is shown in FIG.

A compression coil spring 22 is mounted between the outer surface of the hub 21 and the movable output side pulley OP2, and the hub 21 is rotated by the rotation of the output shaft OS by the torque T applied via the belt V. When is rotated, the cam surface 21a of the hub 21 slides on the cam surface 20a of the torque cam 20 to generate an axial thrust F by the wedge angle α, and the torque cam 20 and the movable output pulley OP2 are fixed to the fixed output pulley. The belt V is pressed toward the OP1 side, and the tension is applied to the belt V. Further, the cam surface 20a of the torque cam 20 has a forward cam surface portion 20a1 and a backward cam surface portion 20a2, and the corresponding cam surface 21a of the hub 21 is similarly forward cam surface portion 21a.
1 and the cam surface portion 21a2 on the retreat side, thrust can be obtained regardless of the traveling direction (rotational direction).

[0009]

However, in the cam surface structure of the torque cam 20 and the hub 21 as described above, due to the structure, the play in which the cam surface 20a and the cam surface 21a do not come into contact with each other around the output shaft OS shown in FIG. It exists in the range of the rotation angle θc. On the other hand, even in the two-way differential clutch CL,
When switching between forward and backward movement, the clamped state of the sprag 6 is obtained only after the drive shaft DS rotates by a predetermined angle θ. Therefore, in the relationship between the rotation angle θc and the angle θ,
There may be a case where the forward / backward switching of the two-way differential clutch CL cannot be effectively performed.

[0010]

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned problems of the prior art, and its gist is to provide a pair of input-side pulleys attached to an input shaft, which are detachable and connectable, and an output shaft. A continuously variable transmission that continuously changes speed of rotation of an input shaft and transmits the rotation to an output shaft by means of a belt mounted between a pair of detachable output side pulleys attached to
The two-way differential clutch includes a main power transmission path that transmits the rotation of the engine through the belt and a sub-power transmission path that transmits the rotation of the engine to the output shaft through a two-way differential clutch.
A rotary shaft for transmitting rotation to the output shaft, an input gear that is relatively rotatable with respect to the rotary shaft, and is rotationally driven by a drive shaft on the engine side, and a rotary shaft that is also rotationally driven by the drive shaft. The input gear and the rotary shaft are clamped based on the differential speed between the input gear and the sub gear, which is interposed between the sub gear having a larger number of teeth than the gear, the input gear, and the rotary shaft. As a belt tensioning mechanism for applying tension to the belt, a cam surface is formed on the outer surface of the movable pulley of the output side pulley concentrically with the output shaft over the entire circumference. And a hub mounted on the output shaft and having a cam surface that contacts the cam surface of the torque cam. By increasing the difference in the number of teeth between the input gear and the sub gear of the two-way differential clutch, the rotation angle of the drive shaft required until the sprag is clamped is set between the cam surfaces of the torque cam and the hub. It should be set smaller than the play angle.

[0011]

[Operation] The sub gear is a gear unrelated to power transmission,
By setting the number of teeth of the sub gear to be large, the rotation angle of the drive shaft required for the sprag to be clamped can be set to be smaller than the play angle between the cam surfaces of the torque cam and the hub. It is possible to effectively switch between forward and backward movement.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. As described in the conventional example, in the cam surface structure of the torque cam 20 and the hub 21 in the belt tension mechanism, the cam surface 20a and the cam surface 21a are structurally different.
Exists in the range of the rotation angle θc around the output shaft OS, and also in the two-way differential clutch CL, the drive shaft DS has a predetermined angle θ when switching between forward and backward travel.
Only after the rotation, the clampable state of the sprag 6 is obtained. Here, when the gear ratio between the input shaft IS and the drive shaft DS is ig and the pulley ratio between the input shaft IS and the output shaft OS is ip, when the drive shaft DS rotates θ (rad), the output shaft OS is θ / It will rotate ig / ip.
Therefore, the condition for switching between forward and backward movement in the two-way differential clutch CL is expressed by the equation of θ / ig / ip <θc (rad). That is, it is represented by θ <θc · ig · ip.

On the other hand, in the two-way differential clutch CL,
The rotation angle θ of the drive shaft DS required from the start of rotation until the sprag 6 is clamped, that is, the rotation angle required for switching between forward and backward movements is the number of teeth of the input gear 2 and the sub gear 8 and the switch angle (the inside required for switching between forward and backward movements). The rotation angle of the holding member 10 with respect to the input gear 2)
=? S / (Z / Zi-Z / Zs). Here, θs is the switch angle (rad), Z is the number of drive gear teeth, Zi is the number of input gear teeth, and Zs is the number of sub gear teeth.

Here, the number of teeth Zs of the sub gear 8 is a parameter that can be freely set without affecting the total reduction gear ratio of the continuously variable transmission, so that Zs satisfies the condition of the above expression.
Is set to a large value and θ is set to be small, the forward / reverse switching of the two-way differential clutch CL can be effectively performed.

[0015]

As described above, according to the present invention, the forward / reverse switching of the two-way differential clutch CL is effectively performed by setting a large number of teeth of the sub gear that is unrelated to the total reduction ratio. There is an advantage that the forward / reverse switching of the two-way differential clutch CL can be reliably performed without affecting.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a continuously variable transmission.

FIG. 2 is a vertical sectional view of a two-way differential clutch.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is an explanatory view of the action of the two-way differential clutch.

FIG. 5 is an explanatory view of the action of the two-way differential clutch.

FIG. 6 is an enlarged view of a main part of FIG.

FIG. 7 is a cross-sectional configuration diagram of a belt tension mechanism.

FIG. 8 is a perspective configuration diagram of a torque cam and a hub that form a belt tension mechanism.

[Explanation of symbols]

 1 rotating shaft 2 input gear 4 output gear 6 sprag 8 sub gear 20 torque cam 21 hub 20a, 21a cam surface DS drive shaft IS input shaft OS output shaft IP1, IP2 input side pulley OP1, OP2 output side pulley V belt CL 2 direction difference Dynamic clutch

Claims (1)

[Claims] 1. An input shaft comprising a pair of separable input-side pulleys attached to an input shaft and a pair of separable output-side pulleys attached to an output shaft. Is a continuously variable transmission that continuously changes the rotation speed of the engine to the output shaft, and transmits the rotation of the engine to the output shaft via the main power transmission path via the belt and the two-way differential clutch. An auxiliary power transmission path, wherein the two-way differential clutch is rotatable relative to the rotation shaft for transmitting rotation to the output shaft,
An input gear that is rotationally driven by a drive shaft on the engine side, a sub gear that is also rotationally driven by the drive shaft, and has a greater number of teeth than the input gear, and is interposed between the input gear and the rotary shaft. A belt tension mechanism for clamping the input gear and the rotary shaft based on a differential speed between the input gear and the sub gear, A torque cam having a cam surface concentric with the output shaft and formed around the entire circumference of the outer surface of the movable pulley of the side pulley; and the torque shaft is attached to the output shaft.
In a continuously variable transmission including a hub having a cam surface that comes into contact with the cam surface of the torque cam, by increasing a tooth number difference between the input gear and the sub gear of the two-way differential clutch, the sprag 2 in a continuously variable transmission, characterized in that the rotation angle of the drive shaft required for clamping is set to be smaller than the play angle between the cam surfaces of the torque cam and the hub.
Directional differential clutch.