JPH02190628A - Clutch and motor-driven power steering device - Google Patents

Abstract

PURPOSE:To transmit torque in either direction only from the driving shaft side by mounting a roller interposingly between a plane part formed at the driving shaft and a driven shaft fitted at the periphery of the plane part, connecting a weight and holding the roller with an elastically deformable cylinder body. CONSTITUTION:In a clutch 15, a hollow driving shaft 21 with a flat part 25 is fixed at a motor shaft 14, and a hollow driven shaft 22 is rotatably fitted at the flat part of the driving shaft 21. A roller 26 is interposingly mounted between a fitting cylinder part 22a and the plane part 25, disposed at the window 28 of a cylinder body 27 fitted between the driving shaft 21 and the fitting cylinder part 22a of the driven shaft and held by a presser spring 29 in the elastically deformable state. The cylinder body 27 is connected to a weight body 31 as well as elastically connected to the driving shaft 21. When the driving shaft starts its rotation, the weight body remains motionless by its inertia, and the roller 26 is engaged to be locked so as to transmit torque. The rotational torque on the driven shaft 22 side runs idle in a minute clearance between the driving shaft 21 and the driven shaft 2, and thereby the transmission of torque does not take place.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention transmits torque in any direction of rotation from one shaft, which is a driving shaft, to the other shaft, which is a driven wheel. This invention relates to a clutch that does not transmit torque from the shaft, and an electric power steering device using the clutch.

(Prior Art) Hydraulic power steering devices are commonly used to reduce the force required to turn the steering wheel of an automobile, but electric power steering devices using a motor have also been known.

For example, in Japanese Patent Application Laid-Open No. 160359/1986, a first pinion driven by a handle and a second pinion driven by a motor are engaged with a rack shaft, and the motor is activated in response to the reaction force acting on the handle. A drive device is disclosed.

(Problem to be Solved by the Invention) However, in the above-mentioned electric power steering device, the motor and pinion are connected directly or through a reduction means, so the rack shaft and the motor are always connected. If the motor fails, you cannot simply drive the rack shaft by operating the steering wheel (but the motor also needs to be driven in reverse, so there is a problem that a greater steering force is required than if there is no power steering device). There is also a problem with the return of the handle.

In view of the above-mentioned conventional problems, the present invention provides a clutch that can transmit torque from the driving side to the driven side, and the driven side can freely rotate. An object of the present invention is to provide an electric power steering device that can suppress the increase in steering wheel speed and improve the returnability of the steering wheel.

(Means for Solving the Problems) The clutch of the present invention has a driven shaft fitted to the outer periphery of a drive shaft via an annular space, and a flat portion formed on the outer periphery of the drive shaft and an inner periphery of the driven wheel. A roller is interposed between the rollers through a small gap, and a cylinder holding the roller so as to be elastically displaceable in the circumferential direction is concentrically connected to the drive shaft via an elastically displaceable connecting means. It is characterized by a weight body connected to its body.

Further, in the electric power steering device of the present invention, a first pinion driven by a handle and a second pinion driven by a motor are engaged with the rack shaft, and the motor is actuated in response to a reaction force acting on the handle. The electric power steering device is characterized in that a clutch is interposed between the motor and the second pinion, transmitting torque from the motor side but not transmitting torque from the second pinion side. do.

(Function) According to the above-mentioned configuration of the clutch of the present invention, when rotational torque acts on the drive shaft and the drive shaft starts rotating in either direction, the cylinder body is connected so as to be displaceable by the connection means. As a result, the drive shaft remains stopped due to the inertia of the weight body, resulting in a phase shift between the drive shaft and the cylindrical body and the driven shaft, and the relative rotation of the flat part on the outer periphery of the drive shaft causes the rollers to move between this flat part and the driven wheel. The rotational torque of the drive shaft is transmitted to the driven shaft via the rollers in a wedge-shaped manner and remains locked. Thereafter, the phase shift between the cylindrical body and the drive shaft is canceled by the elastic restoring force of the coupling means, but since the rollers are in a locked state and are held in the cylindrical body so that they can be elastically displaced, the torque Transmission remains maintained. When torque transmission by the drive shaft stops, the rollers elastically return to a predetermined position on the cylinder, and a minute gap is created between the flat surface of the drive shaft and the inner periphery of the driven shaft.

Conversely, even if a rotational torque acts on the driven wheel, the driven wheel will rotate idly because the rollers are interposed through a small gap.

In this way, rotational torque is transmitted from the drive shaft side to the driven shaft during rotation in either direction, but no torque is transmitted from the driven wheel side to the drive shaft side, resulting in idle rotation.

Further, according to the electric power steering device of the present invention,
Since a latch like this is interposed between the motor and the second pinion driven by this motor, if the rack shaft is operated only by operating the handle due to motor failure, the movement of the rack shaft will be prevented. Accordingly, only the second pinion rotates idly and the motor is not driven in reverse, so a large steering force is not required and the returnability of the steering wheel is improved.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 to 7.

In FIG. 7, 1 is a handle, 2 is a handle shaft, and a first shaft 4 that engages with a rack shaft 5 is connected to the tip of the handle shaft. Further, a detector 3 is interposed in the middle of the handle shaft 2 to detect a reaction force when the handle is operated. Both ends of the rack shaft 5 are connected to knuckle arms 7 via tie rods 6, and the left and right wheels 8 are steered in conjunction with the movement of the rack shaft 5.

9 is a lower arm that constitutes a wheel suspension.

The rack shaft 5 is provided with a driving means 10 having a motor 11.
A second pinion 12 driven by is in mesh with the second pinion 12 .

The motor 11 is driven and controlled by a control circuit 13 based on the detection signal from the detector 3, and rotates a second pinion 12 in the same direction as the first pinion 4, thereby causing the rack shaft 5 to move by the handle 1. It is configured to power assist.

As shown in FIG. 1, the drive means IO includes the motor 11, a clutch 15 attached to the motor shaft 14, and a two-stage planetary planetary planetary system that decelerates and transmits the rotation of the driven shaft 22 to the pinion 12. It is composed of a gear mechanism 16.

To explain the structure of the clutch 15 in detail with reference to FIGS. 2 to 6, a hollow drive shaft 21 is provided at the base end of the motor shaft 14.
are fitted and fixed with pins 23, and a hollow driven shaft 22 is rotatably fitted to the tip of the motor shaft 14 via a roller bearing 24. The driven shaft 22 is formed with a cylindrical inner fitting part 22a that fits into the outer periphery of the drive shaft 21 with an annular space therebetween. , flat portions 25 are formed at three locations in the circumferential direction. A roller 26 is interposed between the flat portion 25 and the inner periphery of the fitting cylinder portion 22a with a small gap therebetween.

This roller 2G is arranged in a window 28 formed in a cylinder 27 fitted between the outer circumference of the drive shaft 21 and the inner circumference of the fitting cylinder part 22a of the driven shaft 22, and is shown in FIG. As such, it is held at an intermediate position in the circumferential direction so as to be elastically displaceable by pressing springs 29 located on both sides in the circumferential direction.

A flange portion 3o extending radially outward is formed at the end of the cylindrical body 27 on the base end side of the motor shaft 14, and a flange portion 3o is formed from the outer periphery of the flange portion 3o to the fitting cylindrical portion 22a of the driven shaft 22 with a gap in the outer periphery. A cylindrical weight body 31 is formed to fit together. Further, an annular protrusion 32 is protruded from the end surface of the flange portion 3o on the base end side of the motor shaft 14, and as shown in FIG. They are connected at four locations by connecting leaf springs 33 so as to be elastically displaceable in the circumferential direction.

The two-stage planetary gear mechanism 16 is disposed on the outer periphery of the driven shaft 22.
A sun gear 41 of the first stage planetary gear mechanism is formed. In FIG. 1, 42 is an internal gear fixed to the housing 40 of the drive means 10 and common to the first and second stage planetary gear mechanisms.

A planetary gear 43 meshes with the sun gear 41 and the internal gear 42, and is rotatably supported by a carrier 45 which is rotatably supported by the shaft portion 12a of the second pinion I2 via a bearing 44. There is. A sun gear 46 of the second stage planetary gear mechanism is fixed to this carrier 45, and a planetary gear 47 meshed with the sun gear 46 and the internal gear 42 is fixed to the shaft portion 12a of the second pinion 12. It is rotatably supported by a carrier 48. The shaft portion 12a of the second pinion 12 is rotatably supported via a bearing 49 by a gear case 50 which slidably holds the rack shaft 5. 51 is a support yoke that supports the rack shaft 5 from the front.

In the above configuration, when the handle 1 is turned, the first pinion 4 is rotated, and the rack shaft 5 is moved to steer the wheel 8, a reaction force acting on the handle shaft 2 is transmitted to the detector 13.
The motor 11 is driven according to the reaction force.

When the motor 11 is driven, rotational torque acts on the drive shaft 21 of the clutch 15 via the motor shaft 14, and the drive shaft 2
1 starts rotating in either direction. Then, cylinder 2
7 is displaceably connected by a connecting plate spring 33, so it remains stopped due to the inertia of the weight body 31, and therefore the driving shaft 21 is connected to the fitting cylinder part 22 of the cylinder body 27 and the driven shaft 22.
a, a phase shift occurs as shown in FIG. The rotational torque of the drive shaft 21 is transmitted to the driven shaft 22 via the rollers 26 in a locked state.

As a result, the second pinion 12 is rotationally driven from the driven shaft 22 via the two-stage planetary gear mechanism 16 in the same direction as the first pinion 4, power assisting movement of the rack shaft 5 by the handle 1, and the wheel 8 is lightly steered.

Note that, after that, the cylinder body 27 and the drive shaft 21 are removed from the state shown in FIG.
The phase shift between the two is canceled by the elastic restoring force of the connecting plate spring 33, but the roller 26 is in a locked state, and the roller 26 is held by the cylindrical body 27 so as to be elastically displaceable by the spring 29. Therefore, torque transmission remains maintained.

Thereafter, when the operation of the handle 1 is stopped, the detection signal from the detector 13 disappears, and the drive of the motor 11 is stopped. As a result, when the torque transmission by the drive shaft 21 is stopped, the rollers 26 are elastically returned to the predetermined position of the cylindrical body 27 by the spring 29, and the flat part 25 of the drive shaft 21 and the fitting cylindrical part 22a of the driven shaft 22 are connected. A small gap is created between the inner circumference and the inner circumference.

Therefore, even if the second pinion 12 is rotationally driven from the rack shaft 5 side and rotational torque is applied to the driven shaft 22, the rollers 26 are connected to the inner periphery of the fitting cylinder part 22a and the drive shaft through a small gap. Since the driven shaft 22 is interposed between the driven shaft 22 and the flat portion 25 of the drive shaft 21, the driven shaft 22 does not idle and torque is not transmitted to the drive shaft 21 side.

Therefore, when the motor 11 fails and the rack shaft 5 is moved via the first pinion 4 by the steering force from the handle 1, there is no need to reverse drive the motor 11, and sudden steering when the motor fails A rise in force can be prevented. Also, when the handle 1 returns, the rack shaft 5 and motor 1
1 is insulated, the return performance of the handle is also improved.

(Effects of the Invention) According to the clutch of the present invention, the roller is interposed between the flat part of the outer periphery of the drive shaft and the inner periphery of the driven shaft, and the weight body is connected to hold the roller so that it can be displaced. and a coupling means for elastically displacing the drive shaft and the barrel.
Rotational torque is transmitted from the drive shaft side to the driven shaft in either direction due to the inertia of the weight body and the locking effect of the rollers on the drive shaft and driven wheel, but the torque is transmitted from the driven wheel side to the drive shaft side. It is possible to obtain a clutch with a simple structure that idles without being released.

Further, according to the electric power steering device of the present invention,
Since a latch like this is interposed between the motor and the second pinion driven by this motor, if the rack shaft is operated only by operating the handle due to motor failure, the movement of the rack shaft will be prevented. Accordingly, only the second pinion rotates idly and the motor is not driven in reverse, so that a large steering force is not required and the return performance of the steering wheel is also improved.

[Brief explanation of the drawing]

1 to 7 show an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional front view of a second pinion drive means for driving the rack shaft, FIG. 2 is an enlarged longitudinal sectional front view of the clutch, Figure 3 is a sectional view taken along the ■-■ arrow in Figure 2, and Figure 4 is IV-I in Figure 2.
5 is a partial detailed sectional view of FIG. 4 showing the state in which the roller is locked, FIG. 6 is a perspective view showing the state in which the roller is held by the cylinder, and FIG. 7 is an electric power FIG. 2 is a schematic configuration diagram of a steering device. 1−・−−−−−・・−・・・・・−・Handle 4−
・-----1--・--・--11 1st pinion 5
・−・・−−−−−・・−・・−・−Rack axis 0−・−
・−・−・−・−・・−1−−−Drive means 2−・−・・
−・−・・−・−Second pinion 5・−−−−−・−
−1−−−・−1111 Latch−・−・−・−
・・・・Drive shaft 2−・−・−・−・−・・Driven shaft 5−・−・−・−・−・・・Plane part 6
・−Roll 7・・・・−・−・・・−・・−Cylinder

Claims (2)

[Claims] (1) The driven shaft is fitted onto the outer circumference of the drive shaft via an annular space, and a roller is inserted between the flat part formed on the outer circumferential surface of the drive shaft and the inner circumferential surface of the driven shaft through a small gap. A cylindrical body holding the roller so as to be elastically displaceable in the circumferential direction is concentrically connected to the drive shaft via an elastically displaceable connecting means, and a weight body is connected to the cylindrical body. Clutch. (2) A first pinion driven by a handle and a second pinion driven by a motor are engaged with the rack shaft,
In an electric power steering device that drives a motor in response to a reaction force acting on the steering wheel, torque is transmitted from the motor side and torque is transmitted from the second pinion side between the motor and a second pinion. An electric power steering device characterized by being equipped with a clutch that does not transmit power.