KR20010021398A - Belt type endless transmission - Google Patents

Abstract

PURPOSE: A belt type continuously variable change gear is provided to improve the abrasion resistance of the belt type continuously variable change gear while facilitating assembling and disassembling, and to shorten the axial length thereof. CONSTITUTION: The continuously variable change gear is provided with a double piston type hydraulic actuator (40) for driving a movable sheave (32) of a primary pulley (10), and a rear piston (54) of the hydraulic actuator (40) is fitted to a boss part (36) of the movable sheave (32) in the condition that a desirable clearance is secured between the inner peripheral surface of the rear piston (54) and the outer peripheral surface of the boss part (36).

Description

Belt type continuously variable transmission {BELT TYPE ENDLESS TRANSMISSION}

The present invention relates to a belt type continuously variable transmission called so-called CVT.

Conventionally, a hydraulic actuator provided with a hydraulic piston is known as operating a sheave of a belt continuously variable transmission, and generally, a hydraulic chamber is constituted by the back of the movable sheave and a piston.

However, in order to obtain a desired pressurization pressure, a large hydraulic pressure area is required. Therefore, the piston diameter and the sheave diameter must be enlarged, resulting in a problem that the transmission itself becomes larger. Thus, for example, as disclosed in Japanese Patent Laid-Open No. 10-274319, a double piston type hydraulic actuator having two pistons has been developed.

According to such a hydraulic actuator, the hydraulic pressure area of the working oil can be increased without increasing the diameter of the whole diameter, that is, the outer diameter of the piston, and there is an advantage that a large driving force can be given to the movable sheave.

By the way, in the double piston type hydraulic actuator in this publication, the inner circumferential portion of the piston (rear piston), which is provided at a position farther from the fixed sheave, is formed on the movable sheave and rotates in the opposite direction to the fixed sheave. It is fitted or press-fitted through the seal at the end of the extension part which extended along the rotating shaft at one end. Specifically, the extended portion is formed such that the large diameter portion and the end portion of the large diameter portion have a small diameter portion having a reduced diameter to form a stepped shape, and the inner circumferential portion of the piston is the outer circumference of the small diameter portion. It is fitted through a thread into or press-fitted. Here, in consideration of the reduction in the number of parts, the press-fit method is preferable, but in this case, there are inconveniences as follows.

Firstly, since the indentation of the rear pistons requires an indentation, the rear pistons are not easily joined, and once the rear pistons are press-fitted, the disassembly becomes virtually impossible.

Secondly, the extended portion of the movable sheave is engaged with the rotating shaft via the ball spline mechanism, and when the rear piston is press-fitted into the spline groove of the ball spline mechanism and the polymerization position in the axial direction of the rotating shaft, the piston is press-fitted. Since the copper spline grooves may be deformed, it is necessary to keep the press-fit position of the rear piston away from the ball spline mechanism. For this reason, the extended part of the movable sheave becomes inevitably long, and eventually, the continuously variable transmission becomes large in its axial direction.

Third, the surface pressure of the rear piston acting according to the hydraulic pressure of the operating oil chamber is high, and the surface pressure fluctuates according to the change in the transmission ratio, so that the rear piston has only one side supporting the rear piston itself. The elastic deformation is repeatedly generated at the circumferential end, that is, the press-in part. Such repetition of elastic deformation causes slight slippage between the inner periphery and the extended portion of the rear piston, and the repetition of the elastic deformation causes a problem that wear occurs between them.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a belt-type endless endless coupling and disassembly of a rear piston, and to prevent abrasion and to shorten its overall length. To provide a transmission.

1 is a schematic view showing a belt continuously variable transmission for a vehicle

2 is a cross-sectional view showing a portion of FIG. 1 in detail.

<Description of the symbols for the main parts of the drawings>

8: Primary shaft (rotary shaft) 10: Primary pulley

16: drive belt 30: fixed sheave

32: movable sheave 36: extended forming part

42: fixed wall

48: front piston (other piston in claim 2)

52: Front oil chamber (other liquid chamber in claim 2)

54: rear piston (piston in claim 1)

60: rear oil chamber (liquid chamber in claim 1)

62: annular clearance 64: step surface

In order to achieve the above object, the present invention according to claim 1 is the belt continuously variable transmission described above, wherein the hydraulic actuator includes a fixed wall fixed to a rotating shaft, and a piston for cooperating with the fixed fixing wall to form a liquid chamber. In addition, the piston is mounted on the extended portion of the movable sheave extending along the rotational shaft in a state in which a desired clearance is secured in the radial direction.

According to the belt continuously variable transmission described above, the piston is mounted leaving a desired gap in the extended portion of the movable sheave. That is, the piston can be mounted on the extended portion of the movable sheave without requiring an indenter. The hydraulic fluid in the hydraulic chamber is guided between the piston and the elongated portion, which in turn leaks between the abutting surfaces of the piston and the elongated portion and lubricates the abutting surfaces.

The present invention according to claim 2 is characterized in that, in the belt-type continuously variable transmission described above, the hydraulic actuator has a double piston structure further comprising another piston which forms a liquid chamber different from the movable sheave.

According to the belt continuously variable transmission, the area subjected to the pressure of the working fluid can be increased without increasing the diameter of the whole, and a large driving force can be given to the movable sheave.

In the belt-type continuously variable transmission according to the third aspect of the present invention, the movable sheave is coupled to the rotating shaft by a ball spline mechanism disposed between the extended portion and the rotating shaft, and the piston is formed of the extended portion. And a coupling portion formed by a ball spline mechanism and a position to polymerize in the axial direction of the rotating shaft.

According to the belt continuously variable transmission, the axial length of the extended portion of the movable sheave, that is, the axial length of the continuously variable transmission can be shortened.

(Embodiment of invention)

1 shows a belt-type continuously variable transformer for a vehicle. The driving force from the engine 1 is the primary shaft of the belt-type continuously variable transmission 6 via the forward and reverse switching device 4 composed of a torque converter 2, a planetary gear mechanism, a clutch, a brake, and the like (in claim). Of rotation) is transmitted to (8).

The continuously variable transmission 6 includes a primary shaft 8, a primary pulley 10 disposed on the primary shaft 8, a secondary shaft 12, and a secondary disposed on the secondary shaft 12. A pulley 14 and an endless driving belt 16 made of steel belts are provided between the pulleys 10 and 14.

The secondary drive shaft 12 is equipped with a transfer drive gear 20, and the transfer drive gear 20 is engaged with the transfer manual gear 22 on the transfer shaft 21. In addition, the final drive pinion gear 24 is attached to the transfer shaft 21, and the final drive pinion gear 24 meshes with the ring gear 28 of the differential device 26.

As enlarged in FIG. 2, the above-mentioned primary bulge 10 includes a fixed sheave 30 and a movable sheave 32, and a drive belt 16 between these sheaves 30 and 32. The V-shaped groove 34 for fitting the grooves is formed. As is apparent from the figure, the fixed sheave 30 is integrally formed with the primary shaft 8, and the movable sheave 32 is mounted on the primary shaft 8 in a movable manner. More specifically, the movable sheave 32 has an extended portion 36 extending along the primary shaft 8 at one end (left side in the drawing) opposite the fixed sheave 30, The extended portion 36 is engaged with the primary shaft 8 via the ball spline 38. Thereby, the movable sheave 32 is attached to the primary shaft 8 so that movement in the axial direction with respect to the primary shaft 8 is possible, but relative rotation in the rotational direction is impossible. Here, the effective area of the ball spline 38, which is the movable range in the axial direction of the movable sheave 32, is set so as to reach one end of the extended portion 36. As shown in FIG.

The movable sheave 32 can be driven by a double piston type hydraulic (hydraulic) actuator 40. The hydraulic actuator 40 includes a fixed wall 42, a movable cylindrical portion 46, a front piston (another piston in claim 2) 48, and a rear piston (piston in claim 1) 54. Equipped.

The fixed wall 42 has the inner circumferential end portion fixed to the primary shaft 8 at a position in one axial end (left side in the figure) than one end portion (left side in the figure) of the extended portion 36, The outer circumferential side is formed as a fixed cylindrical portion 44 extending to the other end in the axial direction (right side in the drawing) so as to surround the elongated portion 36 of the movable sheave 32, and the fixed cylindrical portion 44 Opens toward the movable sheave 32. On the other hand, the movable sheave 32 has a movable cylindrical portion 46 that extends from the outer peripheral side toward the one end (left side in the drawing) at the outer peripheral edge thereof from the outer peripheral side. The tip of 46 is in a positional relationship that surrounds the fixed cylindrical portion 44 from the outside thereof.

A front piston 48 is disposed in the movable cylindrical portion 46, and the front piston 48 has a seal member 50 on the inner circumferential surface of the movable cylindrical portion 46 at its outer circumferential end thereof. And one end in the axial direction so as to be in fluid tight contact with each other, and the inner end of the inner periphery is in fluid tight contact with the outer periphery of the extended portion 36 through the seal member 50. The end surface of the left side in the figure is disposed to abut on the opening end of the fixed cylindrical portion 44. By this structure, the front oil chamber (other liquid chamber in Claim 2) 52 which is divided by the movable sheave 32 and the front piston 48 is formed.

On the other hand, the rear piston 54 is arranged in the fixed cylindrical portion 44, and the inner circumferential end portion of the rear piston 54 has an inner circumference of the fixed cylindrical portion 44 via the seal member 56. The inner end portion is in sliding contact with the surface, and the inner circumferential portion thereof is arranged to fit the outer circumference of the extended portion 36. More specifically, at the end of the extended portion 36 in the axial direction (left side of the drawing), the small diameter whose diameter is smaller than that of the large diameter portion 59 in which the inner circumferential portion of the front piston 48 is in sliding contact. A portion 58 is formed, and the inner circumferential portion of the rear piston 54 is fitted to the outer circumference of the small diameter portion 58. Here, the small diameter portion 18 of the extended portion 36 is formed at a position overlapping with the effective area of the ball spline 38 in the axial direction of the primary shaft 8.

In addition, a snap ring cp is disposed at the small diameter end portion 58 of the extended portion 36 to prevent the rear piston 54 from falling out.

By this structure, the rear oil chamber (liquid chamber in Claim 1) 60 formed by the fixed wall 42 and the rear piston 54 is formed.

As exaggeratedly shown in FIG. 2, the rear piston 54 is desired between the inner circumferential portion of the rear piston 54 and the outer circumferential surface of the small diameter portion 58 of the extended portion 36. Of the small diameter portion 58 and the large diameter portion 59 of the portion 36 in which the end surface of the movable sheave side (right side in the drawing) of the inner end portion is extended so that the annular clearance 62 is secured. It fits in the small diameter part 58 so that the step surface 64 in between may contact.

Here, the annular clearance 62 is formed between the inner circumferential portion of the rear piston 54 and the small diameter portion 58 of the extended portion 36 so that the operating oil in the rear oil chamber 60 is formed. Through this annular clearance 62, the space between the rear piston 54 and the front piston 48 from a slight gap between the inner periphery of the rear piston 54 and the stepped surface 64. Leaks in. Thus, the leaking working oil lubricates the stepped surface 64 of the inner periphery of the rear piston 54 and the extended portion 36 which abut against each other.

In addition, the annular clearance 62 has a degree of leaking the minimum required amount of operating oil in the case of lubrication of the inner periphery of the rear piston 54 and the step surface 64 (see arrow L in FIG. 2). As having a size, the presence of the annular clearance 62 does not impede the increase of pressure in the rear oil chamber 60 or the smooth movement of the rear piston 54.

The front oil chamber 52 and the rear oil chamber 60 described above can receive the supply of the operating oil through a common operating oil passage, not shown, and the front oil chamber 52 and the rear oil chamber 60. The hydraulic pressure in the head) can be controlled by hydraulic control means (not shown) including an oil pump or a pressure regulating valve.

For example, when the oil pressure in both the front oil chamber 52 and the rear oil chamber 60 is increased, the oil pressure in the front oil chamber 52 is pushed to the left by looking at the front piston 48 in FIG. Since the movement of the front piston 48 to the left side is prevented by the fixing wall 42, the front piston 48 is not moved to the left side by the hydraulic pressure in the front oil chamber 52. As a result, Only the movable sheave 32 pressed to the right by the hydraulic pressure in the front oil chamber 52 is moved to the right.

In addition, the hydraulic pressure in the rear oil chamber 60 presses the fixed wall to the left side of the left end wall of the 42 as shown in Fig. 2, but the fixed wall 42 is fixed to the primary shaft 8, so that the fixed wall The 42 is not moved to the left by the hydraulic pressure in the rear oil chamber 60, and as a result, only the rear piston 54 pressed to the right by the hydraulic pressure in the rear oil chamber 60 is moved to the right. As a result, the movable sheave 32 on which the rear piston 54 is mounted is moved to the right.

That is, the movable sheave 32 is subjected to a pressurization by the hydraulic pressure of the rear oil chamber 60 via the rear piston 54 which is in contact with the stepped surface 64 of the extended portion 36, and the front Not only the oil pressure in the oil chamber 52 but also the oil pressure in the rear oil chamber 60 is moved to the right.

That is, when both of the hydraulic pressure in the front oil chamber 52 and the rear oil chamber 60 are increased, the front piston 48 and the rear piston 54 move with each other to move the movable sheave 32 to the right, As a result, the groove width of the fitting groove 34 in the primary pulley 10 is reduced.

In the continuously variable transmission 6 described above, the rear piston 54 of the primary pulley 10 has the desired annular clearance 62 described above between the inner circumferential end portion and the extended portion 36. ) Is fitted to the extended portion 36 of the movable sheave 32, i.e., it is installed without being pressed into the extended portion 36 of the movable sheave 32, so that the installation of the rear piston 54 is performed. In other words, the bond or its decomposition is easy.

In addition, since the rear piston 54 is not press-fitted against the elongated portion 36 of the movable sheave 32, it is generated due to the press-in of the rear piston to the elongate forming portion like the conventional belt type continuously variable transmission. There was no deformation of the spline groove of the ball spline 38 between the extended portion 36 of the movable sheave 32 and the primary shaft 8.

Therefore, as is apparent from FIG. 2, in the axial direction of the primary shaft 8, the rear piston 54 can be arranged in the state where the ball spline 38 is overlapped with each other, and the movable sheave 32 can be disposed. The length of the extended portion 36, that is, the axial length of the continuously variable transmission 6 can be shortened, and the size of the transmission can be reduced.

In addition, since the rear piston 54 is mounted in a state where the annular gap 62 is secured between the extended portion 36, the rear piston 54 and the extended portion 36 are formed as described above. The oil is supplied between the abutting surfaces of the plywoods so that wear of the abutting surfaces is reliably prevented even when the rear piston 54 repeats the elastic deformation.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in this embodiment, although the piston on the primary pulley side is taken as an example, it is also applicable to the piston on the secondary pulley side, and the specific shape and arrangement of each part are within the scope not departing from the technical spirit of the present invention. It can be changed as appropriate.

It goes without saying that the continuously variable transmission of the present invention can be applied to a transmission other than for a vehicle.

As described above, according to the belt continuously variable transmission of the present invention (claim 1), it is not necessary to apply pressure to the engagement of the piston to the movable sheave, so that the engagement and disassembly are easy. In addition, since the working liquid in the liquid chamber is supplied to an abutting surface between the extended portion of the movable sheave and the piston, there is an advantage that the abrasion of these abutting surfaces is also prevented.

In addition, according to the belt type continuously variable transmission of the present invention (claim 2), the hydraulic actuator has a double piston structure, so that the area subjected to the pressure of the working fluid can be increased without increasing the diameter of the whole, so that the movable sheave is large. Driving force can be given.

Further, according to the belt type continuously variable transmission of the present invention (claim 3), since the piston is mounted at a position in which the piston overlaps with the engagement portion by the ball spline mechanism in the extended portion of the movable sheave in the axial direction, the movable sheave is extended. The axial length of the portion, that is, the axial length of the continuously variable transmission can be shortened, and the transmission itself can be miniaturized.

Claims (3)

A movable sheave formed on the rotating shaft, a movable sheave provided freely along the rotating shaft and cooperating with the fixed sheave to form a groove to be fitted for an endless driving belt; In the belt-type continuously variable transmission provided with a hydraulic actuator for driving the shaft in the axial direction of the rotary shaft to vary the width of the groove to be fitted, The hydraulic actuator is, A fixed wall fixed to the rotating shaft, A piston which cooperates with the fixed wall to form a liquid chamber, And the piston is mounted in a state in which a desired clearance in the radial direction is secured to the extended portion of the movable sheave extending along the rotation shaft. According to claim 1, wherein the hydraulic actuator, And a double piston structure further comprising another piston for cooperating with said movable sieve to form another liquid chamber. According to claim 1, The movable sheave is coupled to the rotary shaft by a ball spline mechanism provided between the elongated portion and the rotary shaft, And the piston is mounted at a position where the engaging portion of the extended portion is joined by the ball spline mechanism in the axial direction of the rotating shaft.