JPH02129527A - Steering torque detector - Google Patents

Abstract

PURPOSE:To facilitate spring dimension control by dividing a steering force transmission system into a steering-wheel side transmission system and a steering-gear side transmission system. CONSTITUTION:The transmission system on the side of a steering wheel 2 is rotated by the operation of a handle 26 while causing a U-shaped spring 9 provided in a compressed state to deflect, but a force exceeding the initial force for the compression is required to make the spring 9 deflect. Namely, when the handle 26 is operated, a slightly large reaction force is generated from the beginning. Consequently, when the handle in its stationary state is operated, proper resistance is obtained to have a feeling of neutral in the handle operation. Further, the spring 9 is arranged without requiring large width in the axial direction of a steering shaft 3, so the device is reduced in size. Further, the structure of the spring 9 is simple, so the spring dimension control is extremely easy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a steering torque detection device for detecting steering torque during steering wheel operation, and is mainly used in an electric power steering device.

[Conventional technology]

2. Description of the Related Art As power steering devices for assisting steering wheel operations, there are conventional hydraulic type ones and electric type ones which have been attracting attention in recent years. In an electric power steering device, the electric motor rotates the steering shaft as needed to assist in steering operation. However, if the electric motor and steering shaft are always connected, steering wheel operation becomes unnecessary. In other words, when the electric motor is not energized, the electric motor acts as a resistance, making the steering wheel harder to operate. For this reason, a clutch mechanism is provided that connects and disconnects the electric motor and the steering shaft, and the electric motor and the steering shaft are connected only when assistance with steering wheel operation is required. Although electromagnetic clutches have been common as such latch mechanisms, in recent years, mechanical clutch mechanisms have been proposed to improve the reliability and controllability of clutch operation.

For example, the electric power steering device disclosed in Japanese Utility Model Application Publications Nos. 59-79466 and 79467 has an upper shaft to which a steering wheel is attached at the upper end, and a lower shaft to which the lower end is connected to, for example, a pinion shaft of a steering gear. Inside the shaft and the cylindrical part of the upper shaft,
A clutch hub includes a torsion bar that coaxially and elastically connects the upper shaft and the lower shaft, and is rotatably assembled on the outer periphery of the lower shaft with a plurality of cam surfaces formed on the outer periphery of the lower shaft. A cam follower is interposed between the inner peripheral surface of the upper shaft and the cam follower is held by a gauge connected to the upper shaft. In such a mechanical clutch mechanism,
When a relative rotational displacement occurs between the upper shaft and the lower shaft, the cam follower is sandwiched between the cam surface and the inner circumferential surface, and the lower shaft and the clutch hub are able to rotate together due to the imitation, and the rotation is made through the clutch hub. The driving force of the drive motor is transmitted to the lower shaft.

Here, the magnitude of the driving force of the drive motor is not constant, but is controlled according to the magnitude of the relative rotational displacement. That is, the degree of steering force assistance is determined according to the magnitude of the steering torque. The magnitude of the steering torque is determined by a steering torque detection device, and a conventional steering torque detection device electrically detects the amount of twist (angle) of a torsion bar provided between the upper shaft and the lower shaft. It was done like this.

[Problem to be solved by the invention]

However, in the configuration in which the torsion bar is provided between the upper shaft and the lower shaft, the torsion bar becomes longer in the axial direction, and the steering torque detection device becomes larger. Moreover, when the torsion bar twist is small, the reaction force is small, so
It also had the disadvantage that a feeling of wobbling occurred when operating the steering wheel, and an appropriate neutral feeling of the steering wheel could not be obtained.

[Means to solve the problem]

In order to solve the above problems, the steering torque detection device according to the present invention divides the steering force transmission system into a steering wheel side transmission system and a steering gear side transmission system, and connects both transmission systems via an elastic body. However, in a steering torque detection device that detects steering torque based on the relative rotational displacement of both transmission systems, the above-mentioned elastic body is composed of a U-shaped spring;
The shape spring is provided so as to be elastically deformable within a plane perpendicular to the axial direction of the steering shaft, and is characterized in that it is assembled in a state in which it is compressed by a predetermined amount in advance.

[For production]

In the above configuration, rotation of the steering wheel side transmission system by steering wheel operation is performed with the deflection of the U-shaped spring provided in the compressed state. , a force exceeding the initial force due to the contraction is required. That is, when operating the handle, a somewhat large reaction force is generated from the beginning. As a result, an appropriate response is generated when the steering wheel is moved from a stationary state to a steering wheel operation, and a neutral feeling can be given to the steering wheel operation. Furthermore, since the U-shaped spring is arranged without taking up any width in the axial direction of the steering shaft, the device can be made much smaller in size compared to a conventional device using a torsion bar. Moreover, since the U-shaped spring has a very simple structure, spring size management (spring constant management) is extremely easy.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

The steering torque detection device according to the present invention is provided at the boss portion of the steering wheel 2 together with the clutch mechanism 1, as shown in FIG. The steering wheel 2 is divided from a steering shaft 3 for transmitting steering force to a steering gear (not shown), and is provided so as to be rotatable relative to the steering shaft 3. A driving force relay member 4 is disposed coaxially near the tip of the steering shaft 3, and this driving force relay member 4 has its boss portion 4a fitted near the tip of the steering shaft 3 to fasten the nut 25. It is fixed to the steering shaft 3 and rotates therewith.

As shown in FIG. 1, on the front side of the driving force relay member 4,
A hexagonal cam portion 5 having six cam surfaces 5a is formed. A ring gear 6 having a circular inner circumferential surface 6a with a larger diameter than the hexagonal cam portion 5 is disposed on the outer circumferential side of the hexagonal cam portion 5. This ring gear 6 is coaxial with the driving force relay member 4 and is connected to the steering wheel 2. and is rotatably supported by the outer peripheral surface of the driving force relay member 4. and,
Two cylindrical cam followers 7 are arranged between the circular inner peripheral surface 6a of the ring gear 6 and the cam surfaces 5a of the hexagonal cam portion 5, respectively. - A coil spring 8 is interposed between the pair of cam followers 7 in a natural length state, and in the natural length state of the coil spring 8, there is a gap between each cam follower 7 and the cam surface 5a and the circular inner circumferential surface 6a. A minute gap is formed in each.

As shown in FIG. 3, on the lower surface side of the steering wheel 2, a total of six retaining holes 2a are formed in a circumferential shape in which the pair of cam followers 7, 7 and the coil spring 8 are accommodated, respectively. At the same time, arc-shaped protrusions 2b and 2c that fit into the substantially circular hole 5b formed in the center of the hexagonal cam part 5 in the driving force relay member 4 are formed in opposing arrangement. At the position corresponding to 2c,
The U-shaped spring 9 as an elastic body is attached to the steering shaft 3.
The boss portion 4a is arranged so that it can be elastically deformed in a plane orthogonal to the axial direction thereof, and this elastic deformation is not interfered with by the boss portion 4a. The U-shaped spring 9 is locked in a compressed state at cutouts 5c and 5d formed in the substantially circular hole 5b at locations corresponding to the arcuate protrusions 2b and 2c, and in this compressed and locked state, U-shaped spring 9
A portion near one end side 9a is in contact with a side end surface of the arcuate projection 2b, and a portion near the other end side 9b is in contact with a side end surface of the arcuate projection 2c.

A first bin 10 is erected between one arm of the U-shaped spring 9 having the one end side 9a and the arcuate protrusion 2b, and this first bin 10 is connected to the driving force relay member 4. Fixed. Further, a second bottle 1 is provided on the arcuate protrusion 2b.
1 is fixed as Tachiyaku. Note that these first bins 10,
A line connecting the centers of the second bin 11, the above-mentioned steering shaft 3, and the rotating shaft 19a of the drive motor 19 (described later) is a straight line.

A steering torque detection member 12 is rotatably provided on the U-shaped spring 9 and is fitted into the first bin 10 . The rear end side of the steering torque detection member 12 has a second bin 11
The steering wheel 2 is engaged with the steering wheel 2 to receive the rotational force of the steering wheel 2. In addition, the steering torque detection member 12
The boss portion 4a is provided at the center of the 4a to allow its movement.
A corresponding relief hole 12a is formed. The tip side 12b of the steering torque detection member 12 is located between the other arm of the U-shaped spring 9 having the other end side 9b and the arcuate protrusion 2C, and the tip side 12b is coated with a conductive material. A U-shaped brush 13 consisting of is fixed. This brush 13 is arranged so that it straddles the resistive part 14a and the conductive part 14b of the resistor 14 fixed on the driving force relay member 4, with one tip connected to the resistive part 14a and the other tip connected to the conductive part 14b.
have been contacted by each. Therefore, due to the movement of the brush 13 due to the rotation of the steering torque detection member 12, the resistance portion 14
The resistance value of the circuit connecting the brush 13, the brush 13, and the conductive portion 14b changes, and the steering torque is thereby detected. Note that the tip side 12 of the steering torque detection member 12
An arcuate notch is formed in the arcuate protrusion 2c corresponding to the movement locus b.

Further, a cylindrical portion 4b is formed on the back side of the driving force relay member 4 coaxially with the steering shaft 3, and a holding member 16 is provided on the outer circumferential side of this cylindrical portion 4b via a large diameter ball bearing 15. It is being A small diameter ball bearing 17 is fitted into the holding portion 16a of the holding member 16.
A pinion gear 18 is rotatably supported by the ball bearing 17, and is arranged so as to mesh with the tooth portion 6b of the ring gear 6. As a result, the positional relationship between the pinion gear 18 and the ring gear 6 is established, and tooth skipping and the like are prevented from occurring in their meshing. In addition, the holding part 1
A motor support member 20 is fitted to 6a, and the front end side of the drive motor 19 is supported by this motor support member 20. The pinion gear 18 and the rotation shaft 19 of the drive motor 19 are connected in the hollow part of the motor support member 20.
a is connected. The rear end side of the drive motor 19 is connected to the steering shaft 3 via a bracket 21.
It is fixed to an outer cylinder 22 provided on the outer peripheral side of.

In the above configuration, when the steering wheel 2 is rotated by operating the handle 26, the cam followers 7 of the engagement holes 2a on the lower surface side of the steering wheel 2 are rotated.
The relative position of the cam follower 7 on the upstream side in the rotational direction changes, and the cam follower 7 on the upstream side in the rotational direction is first pushed against the wall surface of the retaining hole 2a and moves.This movement generates a biasing force on the coil spring 8, and this biasing force causes the cam follower 7 on the downstream side in the rotational direction to move. Cam follower 7 moves. Then, the cam follower 7 on the downstream side is caught between the cam surface 5a and the circular inner circumferential surface 6a, and the driving force relay member 4 and the ring gear 6 can rotate together due to the drafting force. Therefore, the rotational force of the drive motor 19 is transmitted to the steering shaft 3 via the rotation fm 19 a → pinion gear 18 → ring gear 6 → drive force relay member 4, thereby assisting steering wheel operation. In addition, when the relative rotational displacement is eliminated due to assistance in steering wheel operation, etc., the cam surface 5a of the cam follower 7 and the circular inner circumferential surface 6
The engagement between the ring gear 6 and the driving force relay member 4 is released, and the state in which the ring gear 6 and the driving force relay member 4 rotate together is released, and in this way, the clutch operation in the clutch mechanism 1 is performed. Note that even after the downstream cam follower 7 is caught between the cam surface 5a and the circular inner circumferential surface 6a, the rotation of the steering wheel 2 is allowed due to the contraction of the coil spring 8, so that the steering wheel 2 and the driving force are relayed. Relative rotational displacement with the member 4 can still be detected.

On the other hand, as the steering wheel 2 rotates, a relative rotational displacement occurs between the steering wheel 2 and the driving force relay member 4, but when the steering wheel 2 rotates, for example, counterclockwise in the figure, the arcuate protrusion 2b is U
It moves while bending the shape spring 9, and accordingly, the second bin 11 moves and the steering torque detection member 12 moves to the first pin l.
Rotate counterclockwise using O as a fulcrum. Due to the rotation of the steering torque detection member 12, the brush 13 on the tip side 12b
moves, a resistance change occurs in the circuit formed by the brush 13 and the resistor 14, and the steering torque is detected. Based on this detected value, the ON/OFF times of the drive motor 19, the magnitude of the output, the rotation direction, etc. are controlled. Here, the distance from the first bin 10 to the tip side 12b of the steering torque detection member 12 is set larger than the distance from the center of the first bin 10 to the center of the second bin 11, and
The amount of movement of the bottle 11 is the tip side 1 of the steering torque detection member 12.
2b, the steering torque can be easily and reliably detected.

Here, the rotation of the steering wheel 2 is performed with the deflection of the U-shaped spring 9 provided in the compressed state, but in order to deflect the U-shaped spring 9 provided in the compressed state, the U-shaped spring 9 provided in the compressed state must be compressed. A force exceeding the initial force is required.

That is, when operating the handle 26, a somewhat large reaction force will be generated from the beginning. As a result, an appropriate response is generated when the steering wheel is moved from a stationary state to a steering wheel operation, and a neutral feeling can be given to the steering wheel operation. Also, U
Since the shape spring 9 is very short in the axial direction of the steering shaft 3, it can be compactly accommodated in the boss portion of the steering wheel 2. In this respect, the device is much smaller than the conventional device using a torsion bar. Moreover, since the U-shaped spring 9 has a very simple structure, spring size management (spring constant management) is extremely easy. Moreover, in this example,
Notches 5c and 5d of the substantially circular hole 5b in the hexagonal cam portion 5
Since it has a simple structure in which the U-shaped spring 9 is pushed in, it is easy to assemble and can be easily adapted to automatic assembly, thereby reducing manufacturing costs. Note that the cross-sectional shape of the above-mentioned U-shaped spring 9 may be any shape such as rectangular or circular. It can also be applied to a hydraulic power steering device. Furthermore, in this embodiment, the steering torque detection device is provided at the boss portion of the steering wheel 2, but the invention is not limited to this. It is also possible to divide it and provide it between them.

〔Effect of the invention〕

As described above, the steering torque detection device according to the present invention divides the steering force transmission system into a steering wheel side transmission system and a steering gear side transmission system, and connects both transmission systems via an elastic body. In a steering torque detection device that detects steering torque based on relative rotational displacement of the system, the elastic body is composed of a U-shaped spring, and this U-shaped spring is elastically deformed in a plane perpendicular to the axial direction of the steering shaft. This configuration is possible and is installed in a state compressed by a predetermined amount in advance.

As a result, an appropriate response is generated when the steering wheel is moved from a stationary state to a steering wheel operation, and a neutral feeling can be given to the steering wheel operation. Furthermore, since the U-shaped spring is arranged without taking up any width in the axial direction of the steering shaft, the device can be made much smaller in size compared to a conventional device using a torsion bar. Furthermore, since the U-shaped spring has a very simple structure, it also has the effect that spring size management (spring constant management) is extremely easy.

[Brief explanation of drawings]

1 to 3 show an embodiment of the present invention, in which FIG. 1 is a plan view showing the internal structure of a steering torque detection device including a clutch mechanism, and FIG. 2 is a plan view showing an internal structure of a steering torque detection device including a clutch mechanism. A sectional view of the torque detection device, and FIG. 3 is a schematic exploded perspective view of the steering torque detection device including a clutch mechanism. 1 is a clutch mechanism, 2 is a steering wheel (steering wheel side transmission system), 3 is a steering shaft (steering gear side transmission system), 4 is a driving force relay member (
Steering gear side transmission system), 5 is a hexagonal cam part, 6 is a ring gear, 7 is a cam follower, 9 is a U-shaped spring, 10 is a first pin, 11 is a second pin, 12 is a steering torque detection member, 13 is a brush , 14 is a resistor, 15 is a ball bearing 16 is a holding member, 17 is a pole bearing, 18 is a pinion gear, and 19 is a drive motor. Figure 1

Claims (1)

[Claims] 1. A steering system in which the steering force transmission system is divided into a steering wheel side transmission system and a steering gear side transmission system, both transmission systems are connected via an elastic body, and the steering torque is detected by the relative rotational displacement of the retransmission system. In the torque detection device, the above-mentioned elastic body consists of a U-shaped spring, and this U-shaped spring is provided so that it can be elastically deformed in a plane orthogonal to the axial direction of the steering shaft, and is assembled in a state in which it is compressed by a predetermined amount in advance. A steering torque detection device characterized in that: