JPH03123831A - Steering torque detecting device - Google Patents

Abstract

PURPOSE:To reduce the size of the device, to obtain a feeling of the neutral state of a steering wheel, and to obtain the detecting device which accurately operates by arranging an elastic body on the inner peripheral side of a cam part and giving rotational resistance by the rotation of the steering wheel. CONSTITUTION:A polygonal cam part 5 which has six cam surfaces 5a on the front is made to project and formed on a driving force relaying member 4 and a projection 52 is formed integrally at the inner peripheral part of the cam part 5. Further, a U-shaped spring 9 as the elastic body is arranged inside the inner peripheral surface 5b on the center side of the cam part 5 so as to deform elastically in a plane crossing the axial direction of the steering shaft 3 at right angles. Then when the steering wheel 2 is rotated, the U-shaped spring 9 which has one end part coupled with the wheel deflects to generate the rotational resistance and rotates relatively with the relaying member 4 fixed to the steering shaft 3 and a steering torque detection member 14 detects the quantity of the relative rotation. In response to the detection, a driving motor 19 rotates the relaying member 4 to assist steering wheel operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a steering torque detection device for detecting steering torque during steering wheel operation, and mainly relates to a steering torque detection device used in an electric power steering device. It is.

(Prior Art) Hydraulic type and electric type power steering devices are conventionally known as power steering devices that assist steering wheel operation.

In an electric power steering device, the steering shaft is rotated by the electric motor as needed to assist in steering operation. However, if the electric motor and steering shaft are always connected, the assistance in steering operation becomes impossible. When it is not necessary, that is, when the electric motor is not energized, the electric motor acts as a resistance, making it difficult to operate the steering wheel. For this reason, a clutch mechanism is provided to connect and disconnect 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, mechanical clutch mechanisms have been proposed in recent years to improve the reliability and controllability of clutch operation.

For example, the electric power steering device disclosed in Japanese Utility Model Application Publication No. 59-79467 includes an upper shaft to which the steering wheel is attached at the upper end, a lower shaft to which the lower end is connected to the pinion shaft of the steering gear, and the upper shaft to which the steering wheel is attached. It has a torsion bar that elastically connects the upper shaft and the lower shaft coaxially within the cylindrical part of the shaft, and is rotatable on the outer periphery of the lower shaft with a plurality of cam surfaces formed on the outer periphery of the lower shaft. Cam followers are interposed between the clutch hub and the inner peripheral surface of the assembled clutch hub, and these cam followers are held by a cage 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 peripheral surface, and the lower shaft and clutch hub are imitated. and can rotate together, and the driving force of the drive motor is transmitted to the lower shaft via the clutch hub.

Here, the magnitude of the driving force of the drive motor is not constant, but varies depending on the magnitude of the relative rotational displacement. That is, the degree of steering force assist is determined according to the magnitude of the steering torque. The magnitude of the steering torque is determined by a steering torque detection device, but conventional steering torque detection devices measure the amount of twist (angle) of the torsion bar provided between the upper shaft and the lower shaft.
was designed to be detected electrically.

[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 configuration is long in the axial direction, resulting in an increase in the size of the steering torque detection device. Moreover, the reaction force of the torsion bar is small when the torsion is small, so a feeling of wobbling may occur when operating the steering wheel.
The disadvantage is that it is not possible to obtain an appropriate neutral feel from the handle.

Additionally, when transmitting rotational force from the steering wheel to the driving force relay member, there are variations in the frictional force during relative rotation between each member, resulting in poor steering force detection accuracy and poor steering feel. It also had some drawbacks.

The present invention has been made in order to eliminate such conventional drawbacks, and an object of the present invention is to provide a steering torque detection device that is significantly smaller in size, provides a neutral feeling to the steering wheel, and operates accurately. The purpose is to

(Means for solving one problem) This invention divides a 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 the relative rotational displacement of It has a steering wheel, a ring member rotatably disposed on the outer periphery of the driving force relay member, and a drive motor that applies rotational force to the ring member, and the driving force relay member includes a steering shaft. A cam part is formed that protrudes in the axial direction and has a cam surface on the outer peripheral surface, and this cam surface and the inner peripheral surface of the ring member are arranged so that the steering wheel rotates relative to the driving force relay member by a certain amount or more. The cam parts are connected to each other via a cam follower, and are disconnected when the amount of relative rotation falls below a certain amount.An elastic body is placed on the inner circumference of this cam part, and the cam part is elastically deformed by rotation of the steering wheel. Bearings are interposed between the driving force relay member and the ring member and between the ring member and the steering wheel.

Further, a support ring is placed on the back of the driving force relay member through a bearing, and the steering wheel and the support ring are tightened with bolts to hold the ring member, the steering wheel, and the driving force relay member through the bearing. It is preferable to configure it so that.

[Effect]

In the above configuration, when the steering wheel is rotated by operating the steering wheel, the elastic body such as the U-shaped spring holder, which is connected at one end to the steering wheel, is deflected and rotational resistance is generated, and the driving force relay member fixed to the steering shaft is also deflected. A relative rotation is made between the steering wheel and the steering wheel, and the amount of this relative rotation is detected by the steering torque detection member. In response to this detection, rotational force is applied from the drive motor to the drive force relay member to assist in steering operation.

Furthermore, relative rotation occurs between the ring member, the steering wheel, and the driving force relay member due to the rotation of the steering wheel, but since bearings are interposed between each member, the resistance during relative rotation between the members is It is small, and the variation in resistance is also small.

In addition, if a U-shaped spring with a compact structure is used as the elastic body, it is possible to generate a relatively large reaction force even with a slight rotation, which makes it suitable for moving the handle from a stationary state to operating the handle. This gives a good feel to the steering wheel, giving a neutral feel to the steering wheel.

〔Example〕

In FIGS. 1 to 3, the steering torque detection device includes a clutch mechanism 1 provided in a boss portion of a steering wheel 2. As shown in FIGS. This steering wheel 2 is
It is coupled so as to be relatively rotatable to a steering shaft 3 for transmitting steering force to a steering gear (not shown). A driving force relay member 4 is fitted onto the tip of the steering shaft 3, and a boss portion 4a of the driving force relay member 4 is connected to the steering shaft 3 by fastening a nut 25.
is fixed to.

The steering wheel 2 includes a handle 26, an annular operating member 22 coupled to the handle, and a plurality of holes 22a for the steering wheel 71 formed in the circumferential direction. As shown in the figure, six protrusions 24 are intermittently formed in the circumferential direction integrally with the operating member 22, and these protrusions 24 are arranged in an arc shape along the operating member 22, and each protrusion 2
The side surfaces 24a of No. 4 are opposite to each other. Further, the operating member 22 has a protrusion 23 and a protrusion 23 that protrude toward the center in a part of the circumferential direction.
8 is formed. This protrusion 23 is formed with a locking groove 29 into which one end of a U-shaped spring 9 (described later) is fitted.

The driving force relay member 4 has a front side shown in FIGS. 2 and 3.
As shown in the figure, a protruding polygonal cam portion 5 having six cam surfaces 5a is formed, and a protrusion 52 protruding toward the center is integrally formed on the inner peripheral portion of the polygonal cam portion 5. A locking groove 59 is formed in which one end of a U-shaped spring 9, which will be described later, is fitted. Further, an inner circumferential surface 5b forming an arcuate surface is formed on the center side of the polygonal cam portion 5, and a U-shaped spring 9 as an elastic body is perpendicular to the axial direction of the steering shaft 3 inside this inner circumferential surface 5b. The boss portion 4a is arranged so as to be able to elastically deform within a plane, and so that this elastic deformation is not interfered with by the boss portion 4a. Further, a flange portion 55 is formed on the outer periphery of the driving force relay member 4 to serve as a bearing receiver as described later.

A ring member 6 having a larger diameter is arranged on the outer peripheral side of the polygonal cam part 5, and a circular inner peripheral surface 6a is formed inside the front part of this ring member 6, and a cylindrical inner peripheral surface 6a is formed behind it. A shaped extension 61 is formed on the inner peripheral surface of which an internal gear 61 is formed.
a is formed.

This ring member 6 is coaxially supported with the driving force relay member 4 and rotatably supported at the outer periphery of the steering wheel 2 and the driving force relay member 4 as described later.

Between the inner peripheral surface 6a of the ring member 6 and the cam surface 5a of the polygonal cam portion 5, two cylindrical cam followers 7 are arranged, for a total of twelve. A coil spring 8 is interposed between the pair of cam followers 7 in a natural length state or in a slightly compressed state, and a minute gap is formed between each cam follower 7 and the cam surface 5a and inner circumferential surface 6a. The circumferential surface of each cam follower 7 on the side opposite to the coil spring 8 is in contact with the side surface 24a of the protrusion 24 of the operating member 22. On the other hand, when the steering wheel 2 is in the neutral position, the cam follower 7 is prevented from being sandwiched between the cam surface 5a, the ring member 6, and the inner peripheral surface 6a.

The U-shaped spring 9 is fixed by having one end 91 fitted into a locking groove 59 formed in the protrusion 52 of the polygonal cam portion 5, and a fixing pin 97 being press-fitted into the recesses 9a, 59a. The other end 92 is fitted into the locking groove 29 formed in the protrusion 23 of the operating member 22, and the fixing pin 98 is inserted into the recess.
1.29b, so that they are fixed so that no wobbling occurs. The means for fixing the U-shaped spring 9 to the locking groove 29.59 is not limited to the above structure, and various fixing means can be employed.

A resistor 14 constituting a steering torque detector is attached to the inside of the inner circumferential surface 5b of the driving force relay member 4, and a U-shaped resistor 14 made of a conductive material is attached so as to straddle the resistive portion 14a and the conductive portion 14b. The tip of the brush 13 is in contact with the brush 13, and this brush 13 is fixed to the protrusion 28 of the operating member 22.

Therefore, when the operating member 22 is rotated by operating the handle 26, the brush 13 attached thereto moves, and the steering torque is detected by a change in the resistance value corresponding to the position of the brush 13 that connects the resistive part 14a and the conductive part 14b. It is now possible to do so.

A ball bearing 62a is interposed between the rear surface of the operating member 22 and the front surface of the ring member 6, and a ball bearing 52a is interposed between the rear surface of the ring member 6 and the flange 55 on the outer periphery of the driving force relay member 4. is interposed therebetween, whereby the ring member 6 is held so as to be rotatable relative to the operating member 22 and the driving force relay member 4.

Further, a support ring 50 is arranged on the rear side of the driving force relay member 4, and a ball bearing 51 is interposed between this support ring 50 and the driving force relay member 4, and this support ring 50 is shown in FIG. As such, it is connected to the operating member 22 by a bolt 71. In this way, the ring member 6 and the driving force relay member 4 are sandwiched and held by the operating member 22 of the steering wheel 2 and the support ring 50 via the respective ball bearings 51, 52a, 62a.

A holding member 1 is attached to the base end of the boss portion 4a of the driving force relay member 4.
6 is fitted externally through a bearing 16G, and a ring 16d
Extraction has been stopped. This holding member 16 is formed with a holding portion 16a extending outward, and this holding portion 16a is coupled to the tip of the motor support member 20.
0 is fixed to an outer cylinder 30 provided on the outer peripheral side of the steering shaft 3 via a bracket 21, and a drive motor 19 is attached to the rear end of this motor support member 20. A drive motor 19 is installed in the hollow part of the motor support member 20.
A rotating shaft 198 passes through the ring, and a pinion gear 18 is formed at the tip of the rotating shaft 19a, and the pinion gear 18 meshes with the internal gear 61a of the ring member 6.

Note that the reason why the teeth of the internal teeth 1i61a are formed at an angle is to ensure smooth engagement with the pinion 18 and to reduce noise.

In the above configuration, when the handle 26 is operated and the operating member 22 is rotated, the side surface 2 of the protrusion 24 of the operating member 22
Of the cam followers 7 that are in contact with the cam follower 4a, the cam follower 7 on the upstream side in the rotational direction of the coil spring 8 first contacts the side surface 24a.
The coil spring 8 is compressed by this movement, and the cam follower 7 on the downstream side in the rotational direction is also pushed in the rotational direction by the biasing force.

At this time, the side surface 24a of the protrusion 24 that was in contact with the cam follower 7 on the downstream side in the rotational direction also moves in the rotational direction, and moves away from the cam follower 7 (retreats). This causes a relative rotational displacement between the handle 26 and the driving force relay member 4, and the cam follower 7 on the downstream side
a and the inner circumferential surface 6a of the ring member 6, and by imitation, the driving force relay member 4 and the ring member 6 are coupled so as to rotate together. For this reason, the drive motor 1
9 is transmitted to the steering shaft 3 via the rotating shaft 19a, the pinion gear 18, the ring member 6, and the driving force relay member 4, thereby assisting steering wheel operation.

In the above operation, since the U-shaped spring 9 has a compact structure, it can generate a relatively large reaction force even for a small rotation angle, and a neutral feeling can be reliably obtained. In addition, both ends 91 and 92 of the U-shaped spring 9 are fixed to the operating member 22 of the steering wheel 2 and the driving force relay member 4 so that no wobbling occurs, so that a neutral feeling is obtained and no wobbling occurs. No sound is generated and the operation is quiet.

Further, when the steering wheel operation is assisted and the relative rotational displacement is eliminated, the cam follower 7 moves between the cam surface 5a and the inner circumferential surface 6.
Since it is no longer pressed between the ring member 6 and the drive force relay member 4, the jamming is released, and the state in which the ring member 6 and the driving force relay member 4 rotate together is released. In this manner, the clutch operation in the clutch mechanism 1 is performed.

Note that the downstream cam follower 7 has a cam surface 5a and an inner circumferential surface 6.
Even after being caught between the coil spring 8 and the steering wheel 2, the rotation of the steering wheel 2 is allowed due to the contraction of the coil spring 8.
Relative rotational displacement between the steering wheel 2 and the driving force relay member 4 is detected.

On the other hand, due to the rotation of the steering wheel 2, a relative rotational displacement occurs between the operating member 22 of the steering wheel 2 and the driving force relay member 4, but if the steering wheel 2 rotates, for example, counterclockwise in FIG. The protrusion 23 of the operating member 22 moves while bending the U-shaped spring 9 while holding the end 92 fitted into the locking groove 29, and the brush 13 moves accordingly. A resistance change occurs in the circuit formed by the resistor 14 and the resistor 14, and the steering torque is detected. Based on this detected value, the on/off state of the drive motor 19, the magnitude of the output, the direction of rotation, etc. are controlled.

Further, ball bearings 51 and 52a are interposed between the driving force relay member 4, the support ring 50, and the ring member 6, which rotate relative to each other, and a ball bearing 62a is interposed between the operating member 22 and the ring member 6. Because of this, the rotational resistance between each member is small and its variation is also small.

Therefore, when each member rotates relative to each other by operating the handle, there is no variation in the transmission of force between each member.
Therefore, a light and stable operating feeling can be obtained when operating the handle.

Furthermore, since there is no variation in the transmission of force between the respective members, it is possible to accurately detect the steering torque.

Conventionally, each member is made to open at zero due to surface contact with each other, so the sliding resistance between each member is large, especially when the handle is operated with a pushing force or tensile force in the axial direction. However, by interposing a bearing such as a ball bearing as described above, such a drawback can be eliminated.

Moreover, since the U-shaped spring 9 is very short in the axial direction of the steering shaft 3, it can be compactly accommodated in the driving force relay member 4.

In this respect, the device is much smaller than the conventional device using a torsion bar.

Furthermore, since the U-shaped spring 9 has a very simple structure, it is extremely easy to manage spring dimensions (spring constant management), and it is easy to assemble and can also be easily adapted to automatic assembly. , it is also possible to reduce manufacturing costs.

Note that the cross-sectional shape of the U-shaped spring 9 can be of various shapes such as rectangular or circular. Further, the above structure can also be applied to a hydraulic power steering device, and 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, and the steering shaft 3 may be provided at the intermediate portion. It may be divided and provided between them.

〔Effect of the invention〕

As explained above, the present invention divides the steering force transmission system into a steering wheel side transmission system and a steering gear side transmission system, connects both transmission systems via an elastic body, and uses the relative rotational displacement of both transmission systems to In a steering torque detection device configured to detect steering torque, the elastic body is configured with a U-shaped spring, and this U-shaped spring is installed to be elastically deformable within a plane orthogonal to the axial direction of the steering shaft. It is something.

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.

Further, since bearings are interposed between the driving force relay member, the ring member, and the steering wheel, the relative rotational resistance among the members is small and the variation thereof is also small. Therefore, when each member is rotated relative to each other by operating the handle, there is no variation in the transmission of force between the members, and therefore, the feeling of operating the handle is excellent. Further, since there is no variation in the transmission of force between each member, there is an advantage that the steering torque can be detected accurately.

Note that the U-shaped spring is arranged without taking up any width in the axial direction of the steering shaft, and the device is significantly smaller than that using a conventional torsion bar. Moreover, 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]

FIG. 1 is a central vertical sectional view of a steering torque detection device including a clutch mechanism showing an embodiment of the present invention, FIG. 2 is a front view of the steering torque detection device with the steering wheel removed, and FIG. 4 is a rear view of the operating member of the steering wheel, FIG. 5 is a sectional view taken along the line V-V in FIG. 2, and FIG. 6 is a partial sectional view of the joint between the operating member and the support member. DESCRIPTION OF SYMBOLS 1... Clutch mechanism, 2... Steering wheel, 3... Steering shaft (steering wheel side transmission system), 4... Driving force relay member, 5... Polygonal cam part, 6... Ring Component 7... cam follower,
9... U-shaped spring, 13... Brush, 14... Steering torque detection member, 16... Holding member, 18... Binion gear, 19... Drive motor, 50... Support ring , 51, 52a, 62a... ball bearing,
55...Edge of driving force relay member. Figure 2

Claims (1)

[Claims] 1. The steering force transmission system is divided into a steering wheel side transmission system and a steering gear side transmission system, and both transmission systems are connected via an elastic body, and steering is performed by the relative rotational displacement of both transmission systems. A steering torque detection device configured to detect torque includes: a driving force relay member fixed to a steering shaft; a steering wheel rotatably attached to the steering shaft coaxially with the driving force relay member; It has a ring member rotatably disposed on the outer periphery of the force relay member, and a drive motor that applies rotational force to the ring member, and the drive force relay member has a ring member that protrudes in the axial direction of the steering shaft. A cam portion having a cam surface is formed on the outer circumferential surface, and this cam surface and the inner circumferential surface of the ring member are engaged with each other via the cam follower when the steering wheel rotates relative to the driving force relay member by a certain amount or more. They are connected and are configured to be uncoupled when the amount of relative rotation falls below a certain amount, and bearings are interposed between the driving force relay member and the ring member and between the ring member and the steering wheel. A steering torque detection device characterized by: 2. A support ring is placed on the back of the driving force relay member via a bearing, and the steering wheel and the support ring are tightened with bolts to connect the ring member, the steering wheel, and the driving force relay member via the bearing. The steering torque detection device according to claim 1, wherein the steering torque detection device is configured to hold the steering torque.