JP2003113918A - Ball screw apparatus for continuously variable transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a stopper mechanism, gear members, etc., from being damaged by an inertia torque of an input shaft for shifting when the inertia torque occurs at the input shaft for shifting because of a rapid stop of rotation by means of the stopper mechanism, which relates to a ball screw apparatus for a continuously variable transmission used for an automobile CVT transmission mechanism, etc. SOLUTION: The ball screw comprises a screw shaft 3, a nut member 2, a plurality of balls 4 rotably interposed between opposing faces of a screw thread 31 of the screw shaft 3 and a screw thread 21 of the nut member 2, a gear member 7 provided between the screw shaft 3 or the nut member 2 and the input shaft 19 for shifting, and the stopper mechanism 18 for limiting an amount of stroke. A tolerance ring 100 is interposed between the gear member 7 and the input shaft 19 for shifting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ball screw device for a continuously variable transmission used in an automobile CVT transmission mechanism or the like.

[0002]

2. Description of the Related Art Conventionally, a V-belt is wound between a V-groove pulley connected to an input shaft from an engine and a V-groove pulley connected to an output shaft to a wheel so that both V-grooves can be used at the time of shifting. There is a continuously variable transmission that changes the belt winding diameter by changing the pulley widths of the pulleys in synchronization with each other to continuously change the output of the engine and transmit it to the wheels.

In this continuously variable transmission, the width of each V-groove pulley is changed by a ball screw device.

In a ball screw device, generally, both ends of a ball passage formed by a screw groove of a screw shaft and a screw groove of a nut member are communicatively connected to each other to form a closed loop, and a ball group is circulated in a ball passage for rolling circulation. By doing so, the screw shaft and the nut member are configured to expand and contract. Then, the nut member is connected to the input shaft for speed change from the motor through a gear and the gear is rotated to change the pulley width.

Further, the ball screw device is provided with a stopper in the rotational direction in order to regulate the stroke amount. For example, the stopper is provided with a convex portion on one side of the screw shaft and the nut member and a concave portion on the other side, and the convex portion fits into the concave portion during expansion / contraction operation, thereby restricting further expansion / contraction operation.

[0006]

In the conventional ball screw device for a continuously variable transmission, the rotation of the nut member is suddenly stopped when the stopper function works. For this reason, there is a problem that the inertia torque of the input shaft for gear shift causes an excessive torque to act on the gear shift system including the ball screw device, and the stopper, the gear, and the like are damaged.

According to the present invention, when inertia torque is generated in the shift input shaft due to abrupt rotation stop by the stopper mechanism, damage to the stopper mechanism, gear member, etc. due to the inertia torque of the shift input shaft can be prevented. An object of the present invention is to provide a ball screw device for a transmission.

[0008]

A ball screw device for a continuously variable transmission according to the present invention comprises a screw shaft having a thread groove formed on an outer peripheral surface thereof,
A nut member that is concentrically rotatable relative to the outer circumference of the screw shaft and has a thread groove formed on the inner peripheral surface, and is freely rollable between the thread groove of the screw shaft and the facing surface of the thread groove of the nut member. A plurality of balls, a gear member provided between the screw shaft or the nut member and the input shaft for speed change, and a stopper mechanism for restricting the stroke amount of the screw shaft and the nut member, A device for converting torque input from the shift input shaft via the gear member between the nut member and the screw shaft into thrust, which is provided between the gear member and the shift input shaft. It is characterized in that a torque limiter mechanism is interposed.

The torque limiter mechanism includes, for example,
Use a tolerance ring.

According to the ball screw device for a continuously variable transmission of the present invention, the torque limiter mechanism is interposed between the gear input member for transmitting the torque of the shift input shaft to the screw shaft or the nut member and the shift input shaft. Therefore, when inertia torque is generated in the speed-change input shaft due to abrupt rotation stop by the stopper mechanism, the torque limiter mechanism can absorb the inertia torque in the speed-change input shaft.

Further, the tolerance ring has a simple structure and can be manufactured at low cost.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding one embodiment of the present invention,
A description will be given based on FIGS. 1 to 6.

FIG. 1 is a longitudinal sectional view of a ball screw device for a continuously variable transmission in a contracted state, and FIG. 2 is a longitudinal sectional view of the ball screw device for a continuously variable transmission in an extended state.

FIG. 3 is an exploded perspective view of the ball screw device for a continuously variable transmission, and FIG. 4 is a partially cutaway perspective view of its assembled state.

Further, FIG. 5 is a perspective view of a tolerance ring which is a torque limiter mechanism, and FIG. 6 is a sectional view thereof.

In the ball screw device 1 for a continuously variable transmission of the illustrated example, a screw groove 21 provided on the inner peripheral surface of the nut member 2,
The ball 4 has a structure in which a plurality of balls 4 are interposed in the cage ring 5 at equal intervals around the circumference with a thread groove 31 provided on the outer peripheral surface of the screw shaft 3, and the plurality of balls 4 circulate. It has a structure called a so-called internal circulation type in which the top 6 circulates.

A plurality of screw grooves 21 are formed on the inner peripheral surface of the nut member 2, and each screw groove 21 is a closed loop which is independent by a single circulating top 6. Further, the screw shaft 3 is formed with one screw groove 31 which is continuous from one shaft end to the other shaft end. The thread groove 21 of the nut member 2 and the thread groove 31 of the screw shaft 3 are set to have the same lead angle. The balls 4 arranged in the closed thread groove 21 are independently circulated and circulated.

Specifically, the retainer ring 5 is provided so that a plurality of balls 4 are arranged at equal intervals on the circumference so as not to interfere with each other. The cage ring 5 is made of a thin cylindrical member, and a plurality of ball pockets 51 having an elongated hole along the axial direction are provided at several places on its circumference. Two ball pockets 51 are provided for each ball pocket 51. The balls 4 are stored one by one.

The circulating top 6 is provided in each thread groove 2 of the nut member 2.
The upstream side and the downstream side of 1 are individually connected for communication, and the group of balls 4 on the downstream side of the thread groove 21 is returned to the upstream side by overcoming the thread (land portion) 32 of the screw shaft 3. 2 is fixed by an adhesive in a state of being fitted and attached to a single through hole 22 formed by penetrating in the radial direction 2. That is, the ball circulation groove 6 is formed on the inner diameter side surface of the circulation top 6.
1, 62 are provided, and the ball circulation grooves 61, 62 are provided.
Has a meandering shape so as to get over the screw thread (land portion) 32 of the screw shaft 3 from the downstream side to the upstream side of the thread groove 21 and return.

Further, the nut member 2 is connected via a gear member 7 to a speed change input shaft 19 which is rotated by a rotary power source (not shown) such as a motor. The gear member 7 is
A metal bracket 8 whose upper half has a substantially U-shaped cross section, a resin gear 9 integrally formed on the outer peripheral surface of the outer tubular portion 81 of the bracket 8, and a shift input shaft 19 are externally fitted. The gear 9 and the reduction gear 91 mesh with each other. The nut member 2 is fitted in the inner peripheral surface of the outer tubular portion 81 of the bracket 8 of the gear member 7, and the convex portions 82 and the nut member 2 provided at several places on the circumference of the base portion of the outer tubular portion 81. By fitting the recesses 23 provided at several places on the inner side in the fitting direction in the axial direction,
The gear member 7 and the nut member 2 are coupled so as not to rotate relative to each other.

The bracket 8 is rotatably supported by a cylindrical shaft 11 inserted through a rolling bearing 12 into the central hole of the screw shaft 3 so as to be movable in the axial direction. Further, the screw shaft 3 is supported via a rolling bearing 14 with respect to the input shaft 13 that is spline-fitted to the inner diameter side of the cylindrical shaft 11. It should be noted that a pair of flanges 15 and 1 having opposed surfaces are tapered on one end side in the axial center direction of the cylinder shaft 11 and the input shaft 13.
6 are distributed and provided. Flange 15,1
The distance between the facing surfaces of 6 is adjusted by rotating the nut member 2 with respect to the screw shaft 3 while rotating the nut member 2 in the axial direction, and the belt 17 wound around the facing surfaces of the flanges 15 and 16 is wound. The hanging diameter is changed.

The retainer ring 5 is attached to the nut member 2 in a state of being substantially immovably positioned in the axial direction and in a relatively rotatable state. Therefore, the enlarged diameter portion 24 is provided at the fixed side end portion of the nut member 2, and
One end of the cage ring 5 is provided with a flange 52 radially outward.
And the flange 52 of the retainer ring 5 is fitted into the expanded diameter portion 24 of the nut member 2, and the spacer 1 for preventing the expanded diameter portion 24 of the nut member 2 from coming off.
0 is press-fitted and fixed internally. However, the spacer 10 is separated from the step wall surface 25 formed at the boundary between the enlarged diameter portion 24 of the nut member 2 and the portion where the screw groove 21 is formed, and the cage is provided between the spacer 10 and the step wall surface 25. The flange 52 of the ring 5 is arranged with play in the axial direction. As a result, the cage ring 5 is substantially immovable with respect to the nut member 2 in the axial direction and is allowed to rotate relatively.

Further, with respect to the bracket 8 and the screw shaft 3,
A stopper mechanism for forcibly stopping the nut member 2 at a predetermined position in the reduction direction is provided. The stopper mechanism is
Stopper pin 18 projecting in the axial direction on the inner surface of the screw shaft 3
And a notch 84 which is provided on the inner peripheral surface of the inner tubular portion 83 of the bracket 8 and whose inner portion is gradually deepened. When the nut member 2 shrinks, the nut member 2
The notch 84 of the bracket 8 that rotates integrally with the screw shaft 3
When the stopper pin 18 contacts the innermost portion of the notch 84, the nut member 2 and the bracket 8 are forcibly stopped.

Further, the shifting input shaft 19 and the reduction gear 91
Tolerance ring 1 that serves as a torque limiter mechanism between
00 is inserted. The tolerance ring 100 is shown in FIGS.
As shown in FIG. 2, the corrugated steel sheet having elasticity is formed in an annular shape, and the peak portion 101 and the valley portion 1 are formed along the outer peripheral surface.
02 are alternately arranged and have elasticity in the radial direction. The spring constant of the tolerance ring 100 changes depending on the plate thickness, the pitch, the width, the shape, the height, etc. of the crests 101, depending on the magnitude of the inertia torque generated in the shift input shaft 19.
A tolerance ring 100 that can absorb the inertia torque is used.

The tolerance ring 100 is provided by being externally fitted in a circumferential groove 103 formed on the outer peripheral surface of the speed change input shaft 19, and may be fixed to the speed change input shaft 19 by adhesion or the like as appropriate. Then, the reduction gear 91 is fitted onto the outer periphery of the tolerance ring 100, the crests 101 of the tolerance ring 100 are pressed against the inner peripheral surface of the reduction gear 91, and the reduction gear 91 is held by the elastic force of the tolerance ring 100. .

Next, the operation of the ball screw device 1 described above will be described. First, when the gear member 7 and the nut member 2 are rotated by driving a motor (not shown), the nut member 2 itself rotates and is guided by the screw shaft 3 to linearly move in one axial direction thereof. As a result, the state shown in FIG. 1 is changed to the state shown in FIG. On the other hand, when the motor is driven in the reverse rotation direction, the nut member 2 is moved in the other axial direction while rotating in the opposite direction to the above,
For example, the state shown in FIG. 2 changes to the state shown in FIG.

As shown in FIG. 1, the ball screw device 1 for a continuously variable transmission is in a contracted state, the stopper pin 18 abuts against the innermost portion of the notch 84, and the nut member 2 and the bracket 8 are forcibly stopped. Then, an inertia torque is generated in the shift input shaft 19. However, the inertia torque is absorbed by bending the mountain portion 101 of the tolerance ring 100 fitted onto the gearshift input shaft 19 in the rotational direction. As a result, the inertia torque is not transmitted to the speed reduction input shaft 19 to the reduction gear 91,
Excessive torque does not act on the transmission including the ball screw device. Therefore, it is possible to prevent the stopper pin 18 and the resin gear 9 from being damaged.

Similarly, as shown in FIG. 2, the ball screw device 1 for a continuously variable transmission is in an extended state, and the flanges 15, 1 are
6 contact each other and the nut member 2 and the bracket 8
Input shaft 19 for speed change even when is forcibly stopped
The inertial torque can be absorbed by the tolerance ring 100.

Moreover, the tolerance ring 100 has a simple structure, and the cost of the ball screw device 1 for a continuously variable transmission can be reduced.

The present invention is not limited to the above-mentioned embodiments, and various applications and modifications can be considered.

For example, although the torque limiter mechanism is the tolerance ring 100, the torque limiter mechanism is not limited to this, and may be any one as long as it can absorb the inertia torque of the transmission input shaft 19 by bending in the rotational direction. For example, a ring-shaped rubber material may be externally fitted to the speed-change input shaft 19.

Further, the ball screw device 1 for the continuously variable transmission described above.
Is connected to the nut member 2 via the gear member 7 for shifting the input shaft 1
The torque is applied from 9 to reciprocate in the axial direction, but the nut member 2 is fixed, and the torque is applied to the screw shaft 3 from the speed change input shaft 19 via the gear member 7. It may be reciprocally moved in the axial direction.

[0033]

According to the ball screw device for a continuously variable transmission of the present invention, when inertia torque is generated in the shift input shaft due to abrupt rotation stop by the stopper mechanism, the stopper due to the inertia torque of the shift input shaft is generated. The effect of preventing damage to the mechanism, the gear member, etc. is obtained.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a ball screw device for a continuously variable transmission in a reduced state according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a ball screw device for a continuously variable transmission in an extended state according to an embodiment of the present invention.

FIG. 3 is an exploded perspective view of a ball screw device for a continuously variable transmission according to an embodiment of the present invention.

FIG. 4 is a partially cutaway perspective view of a ball screw device for a continuously variable transmission according to an embodiment of the present invention.

FIG. 5 is a perspective view of a tolerance ring according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view of the tolerance ring in the embodiment of the present invention.

[Explanation of symbols]

1 Ball screw device 2 Nut member 3 screw shaft Four balls 7 Gear member 9 gears 18 Stopper pin (Stopper mechanism) 19 Speed change input shaft 84 Notch (Stopper mechanism) 91 reduction gear 100 Tolerance ring (torque limiter mechanism)

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3J050 AA02 BA03 BB05 CE10 DA02                 3J062 AA02 AA18 AB22 AB34 AC03                       AC07 BA19 CD23 CD77 CF03                       CF04 CF06 CF32 CF44

Claims (2)

[Claims] 1. A screw shaft having a thread groove formed on an outer peripheral surface thereof, a nut member concentrically rotatable relative to the outer circumference of the screw shaft and having a thread groove formed on an inner peripheral surface thereof, and a screw shaft of the screw shaft. A plurality of balls rotatably interposed between the screw grooves and the facing surfaces of the screw grooves of the nut member, a gear member provided between the screw shaft or the nut member and a speed change input shaft, and the screw A shaft and a stopper mechanism that restricts the stroke amount of the nut member are provided, and the torque input from the shift input shaft via the gear member is converted into thrust between the nut member and the screw shaft. A ball screw device for a continuously variable transmission, wherein a torque limiter mechanism is interposed between the gear member and the speed change input shaft. 2. The ball screw device for a continuously variable transmission according to claim 1, wherein the torque limiter mechanism is a tolerance ring.