JPH0221347Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a rack-and-pinion power steering device having electric driving force, hydraulic driving force, or the like as power assist.

[Conventional technology]

Generally, in a power steering device, a steering wheel steering torque is detected as a signal by some kind of detection means, and a power assist is generated for the steering wheel steering torque by a control means such as a power steering valve or a controller.

For example, in a hydraulic power steering device, steering torque is mechanically detected using a torsion bar or the like, and displacement of a spool valve or a rotary valve as a control means is controlled to generate power assist.

On the other hand, in an electric or electrohydraulic power steering device, steering torque is detected as some kind of electric signal, and this signal is sent to a predetermined control device to generate power assist.

As a steering torque detection means in this latter case,
Conventionally, the following two examples are given.

One of them is that, as shown in FIG. 9, the steering torque is proportional to the torsion angle of the torsion bar 62, which rotates together with the steering shaft 61. This is a method of direct detection using an element. That is, when the steering wheel is rotated, the torsion bar 62 is twisted and the magnet 64 is twisted.
The relative angle between the magnetic sensor 65 and the guide 63 changes, and the magnetic flux passing through the magnetic sensor 65 changes. This change in magnetic flux is detected by a magnetic sensor 65, which is converted into an electrical code such as a voltage, and input into an electronic control unit 67. And for a given input steering torque,
The electric signal amplified by the electronic control unit 67 operates the electric motor 68, and the necessary steering torque is applied to the steering shaft 61 via the reduction gear 68A, clutch 68B, and gear 68C.

In addition, in other examples, FIGS. 10 and 11 (1
As shown in the A-A sectional view of Figure 0), since the steering torque has a constant relationship with the torsion angle of the torsion bar 81 connected to the input shaft 71, the displacement of the torsion angle of the torsion bar 81 can be expressed as Converts the amount of linear displacement of the spool 82 through mechanisms 83, 83A, 83B, and 83C, and extracts this amount of displacement as an electric signal for detecting steering torque by a detection device 84 such as a potentiometer or a differential transformer. (Details are shown in Japanese Patent Application Laid-Open No. 59-11965).

[Problem that the invention attempts to solve]

However, since the magnetic sensor (optical sensor) used in the first steering torque detection means shown in FIG. 9 is a semiconductor, its temperature characteristics are not good, and it is detected as the torsion angle of the torsion bar and the steering torque conversion amount. It is not necessarily proportional to the amount of electricity that should be
In order to establish a proportional relationship, an electronic circuit unit is required, which increases the number of parts and complicates the system, which also has the disadvantage of being more prone to failure. Furthermore, magnetic sensors (optical sensors), which are semiconductors, are easily affected by dust and dirt, and have the disadvantage of requiring countermeasures against such external disturbances.

Further, although the steering torque detection means using the planetary gear mechanism shown in FIGS. 10 and 11 has a proven track record, it has the disadvantage that the structure is extremely complicated and expensive.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a rack-and-pinion power steering device having a steering torque detection device with a simple structure.

[Means for solving problems]

In order to achieve such an object, the present invention provides a pair of bearing parts, in which a pinion shaft integral with a pinion which is disposed in a gear box with a rack in between and engages with the rack is inserted, through an elongated hole formed in the gear box. The rack is supported so as to be movable only in the axial direction, and the amount of movement of the pinion shaft within the range of the play of the bearing portion is measured by a steering torque detection means to detect the steering torque of the steering wheel, and the detected signal is detected. It is configured to generate power assist as a base.

[Effect]

According to the above configuration, the pinion shaft moves in the axial direction of the rack via the bearing in proportion to the steering torque of the steering wheel, and the amount of movement of the pinion shaft is measured by the steering torque detection means and taken out as a signal to be used for power assist. The control member is controlled to provide power assist to the steering torque.

〔Example〕

Hereinafter, the present invention will be explained based on embodiments shown in the drawings. 1 to 5 are diagrams showing a first embodiment of the present invention.

Fig. 1 is a schematic diagram of a rack-and-pinion type power steering device that uses electric driving force as power assist, Fig. 2 is a longitudinal sectional view of the gearbox showing the meshing state of the rack and pinion, and Figs. 3 and 4 are FIG. 5 is a cross-sectional view taken along line B-B and line C-C in FIG. 2, showing the relationship between the bearing portion and the gearbox, and FIG. 5 is a longitudinal cross-sectional view showing the steering torque detection means.

In FIG. 1, a wheel 1 is connected to a steering link 3 via a knuckle arm 2. In FIG. A rack 4 integrally formed with the steering link 3 and a handle 5
The pinion 7 connected via the input shaft 6 to the
They are engaged in gearbox 7B.

The rack-and-pinion power steering device uses pinion 7 and rack 4 to control the rotation of the steering wheel 5.
The signal is transmitted to the steering link 3 via a mechanism consisting of the following, and the direction of the left and right wheels 1 is changed.

A motor 9 is installed to assist the steering force of this rack-and-pinion type power steering device, and a pinion 9A attached to the end of the output shaft of the motor 9 meshes with the rack 4, causing the rack 4 to slide, thereby providing power assistance. It is beginning to cause The forward/reverse rotation and output control of the motor 9 are performed by the controller 8 processing an electric signal detected by the steering torque detection device 7A.

In Figure 2, 4 is a rack, 7 is a pinion,
7B is a gear box, 21 and 22 are a pair of bearing parts, and 21A and 22A are bearing parts 21 and 2.
2 is an outer race, 21B and 22B are inner races fitted to the pinion shaft 7C, and 23 is a swing lever.

The pinion 7 that meshes with the rack 4 is integrally formed with the pinion shaft 7C.
are supported by bearing portions 21 and 22 placed in the front and rear with the rack 4 in between. Also the second
As shown in the figure, a spring pin 24 is inserted into the left end of the pinion shaft 7C.

As shown in FIGS. 3 and 4, the gearbox 7B is formed with an elongated hole 26 that supports the bearing portions 21, 22 so as to be movable only in the left-right direction, that is, in the axial direction of the rack 4. Swing lever 2
3 is disposed orthogonal to the pinion shaft 7C, its center portion is fitted onto the pinion shaft 7C, and is configured to swing about a fulcrum portion 23A supported by a portion within the gearbox 7B. Also, the tip 2
3B protrudes from gearbox 7B.

As shown in FIG. 5, the steering torque detection means consists of a leaf spring 31 and a strain gauge 32.
One end is fixed upright to the tip 31B of the swing lever 23, and the other end is fixed to a fixed piece 33 attached to the gearbox 7B. Further, strain gauges 32 are attached to both sides of the leaf spring 31.

Next, the operation of the embodiment of the present invention will be explained.

The swing lever 23 swings approximately in proportion to the steering torque due to the balance between the spring pin 24 and a coil spring (not shown), and the amount of movement of the swing lever 23 is approximately proportional to the terminal voltage detected by the strain gauge 32. Proportional. Therefore, a voltage substantially proportional to the steering torque can be obtained by the strain gauge 32, which is the steering torque detection means.

That is, when the handle 5 is rotated clockwise (in the direction of arrow a in FIG. 3), the loaded wheels 1, knuckle arms 2, steering links 3, and racks 4 are in one fixed state, so the pinion 7 is rotated. The pinion shaft 7C, which receives a reaction force from the rack 4 and is integrated with the pinion 5, moves to the bearing portion 21,
22 to the left within the range of the play C formed between the outer peripheral surfaces of the bearing parts 21 and 22 and the elongated hole 26. In conjunction with this, the swing lever 23 also swings in the same direction about the fulcrum portion 23A. Then, the leaf spring 31 deforms and the strain gauge 32
The resistance value changes, and this change in resistance value is measured as a voltage using a bridge or an oscillograph (not shown). In this way, the strain gauge 32 detects the voltage change due to the deformation of the leaf spring 31, and this electric signal is processed by the controller 8 to determine the rotation direction and output of the motor 9, thereby generating power assist for rightward steering. It is.

On the other hand, when the handle 5 is rotated counterclockwise, the pinion shaft 7C moves in the opposite direction, that is, to the right, within the range of the play C, which is the same as when the handle 5 is rotated clockwise. This action produces power assist for leftward steering.

FIG. 6 is a longitudinal sectional view showing a steering torque detecting means 7A according to a second embodiment of the present invention. In this embodiment, a potentiometer 41 is provided as a steering torque detecting means in place of the leaf spring 31 and strain gauge 32 of the first embodiment, and the potentiometer 41 is fixed to the outside of the gear box 7B. The tip 23B of the swing lever 23 is attached to the fixed piece 42.
The lever 23 is connected to the tip 23B of the swing lever 23 by a connecting rod 43.
The resistance value of the potentiometer 41 changes in proportion to the amount of swing of the swing lever 23.
The steering torque can be detected as a resistance change of the potentiometer 41. Note that a differential transformer may be provided in place of the potentiometer 41.

FIG. 7 is a longitudinal sectional view showing a steering torque detecting means 7A according to a third embodiment of the present invention. In this embodiment, a permanent magnet 51 and a magnetic sensor 52 are provided as steering torque detection means in place of the leaf spring 31 and strain gauge 32 of the first embodiment.
is fixed to the tip 23B of the swing lever 23, and the magnetic sensor 52 is disposed opposite the permanent magnet 51 on a fixed piece 53 fixed to the outside of the gearbox 7B. As the swing lever 23 swings, the magnetic flux passing through the magnetic sensor 52 changes, and the steering torque can be detected as a change in the magnetic flux of the magnetic sensor 52.

12 and 13 show a permanent magnet 6 as a steering torque detecting means 7A according to a fourth embodiment of the present invention.
0 and a magnetic field sensor consisting of a magnetoresistive element 61. In FIG. 12, a permanent magnet 60 is fixed to the tip 23B of the swing lever 23, and the swing lever 23 is moved from the center of the pinion shaft 7C.
The magnetoresistive element 61 is positioned in the radial direction passing through the tip 23B of the permanent magnet 60
is fixed via a guide 62. Also the first
In FIG. 3, a permanent magnet 60 is fixed to the tip 23B of the swing lever 23, and a magnetic resistance element 61 is attached to a guide 62A substantially parallel to the axis center line of the pinion shaft 7C and facing the side of the permanent magnet 60. Fixed through. In addition, in the above embodiment, the permanent magnet 6
0 is fixed to the rocking lever 23 side, and the magnetic resistance element 61 is fixed to the fixed guides 62, 62A, but in contrast, the magnetic resistance element 61 is fixed to the rocking lever 23 side, and the permanent magnet 60 is fixed to the rocking lever 23 side. Guides 62, 62
They may each be fixed to the A side.

According to the embodiment, since the strength of the magnetism acting on the magnetic resistance element 61 changes as the swing lever 23 swings, the steering torque can be detected as a change in the electrical resistance of the magnetic resistance element 61.

FIG. 8 shows a rack-and-pinion power steering system according to a fourth embodiment of the present invention, in which electric drive force is used as power assist in the first embodiment, and hydraulic drive force is used as power assist instead of electric drive force. FIG. 2 is a schematic diagram of the device, and is different from the first to second embodiments (first to second embodiments) in that the means of power assist is different.
There are some differences from Figure 6).

In FIG. 8, an electric signal detected by a steering torque detecting means 7A such as a strain gauge, a potentiometer, or a magnetic sensor is input to a controller 8, and by controlling a control valve 54, a conduit 57 is connected to a cylinder 58. Pressure oil is supplied through the link 3 to provide power assist to the link 3. In addition, in FIG. 8, 55 indicates a hydraulic pump, and 56 indicates an oil tank.

[Effect of idea]

As mentioned above, according to the present invention, the steering torque is detected as an electrical quantity using the existing swing lever and the power assist motor or control valve is controlled, so the structure is simple. A rack-and-pinion power steering device having a steering torque detection means can be obtained.

[Brief explanation of drawings]

1 to 5 relate to a first embodiment of the present invention, in which FIG. 1 is a schematic diagram of a rack-and-pinion power steering device, and FIG. 2 is a vertical cross-sectional view of a gearbox in FIG. Figure 3 is B- in Figure 2.
FIG. 4 is a longitudinal sectional view taken along the line C-C in FIG. 2, FIG. 5 is a longitudinal sectional view showing the steering torque detection means, and FIG. 6 is a second embodiment of the present invention. FIG. 7 is a vertical cross-sectional view showing a steering torque detecting means according to a third embodiment of the present invention, and FIG. 8 is a longitudinal cross-sectional view showing a steering torque detecting means according to a fourth embodiment of the present invention. A schematic diagram of a rack-and-pinion type power steering device, FIG. 9 is a sectional view showing a conventional first steering torque detection means, and FIG. 10 is a schematic diagram of a power steering device having another conventional steering torque detection means. FIG. 11 is a sectional view of the main part of the steering torque detection means, FIG. 12 is a longitudinal sectional view showing the steering torque detection means using a magnetoresistive element, and FIG. 13 is a longitudinal sectional view of the steering torque detection means using a magnetoresistive element. It is a longitudinal cross-sectional view showing a modification. 4...Rack, 7...Pinion, 7A...Steering torque detection means, 7B...Gearbox, 7C...
...Pinion shaft, 21, 22...Bearing part, 2
3... Swing lever, 26... Long hole, 31... Leaf spring, 32... Strain gauge, 41... Potentiometer, 51... Permanent magnet, 52... Magnetic sensor.

Claims (1)

[Scope of utility model registration request] A pair of bearing parts, in which a pinion shaft integral with a pinion which is disposed in a gear box with a rack in between and engages with the rack, is inserted, can be moved only in the axial direction of the rack through an elongated hole formed in the gear box. A steering torque detecting means measures the amount of movement of the pinion shaft within the range of play of the bearing portion, detects steering wheel steering torque, and generates power assist based on the detected signal. A rack-and-pinion power steering device characterized by: