JPS63541Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an electric power steering device using a rack and pinion type steering gear that can share parts with a manual steering device.

Conventionally, a sensor electrically detects the steering torque of a steering shaft, and a motor that rotates and drives a steering gear device connected to the steering shaft in response to a signal detected by the sensor provides a force-increasing effect. Electric power steering devices are known.

However, when a device using such a rotary drive type motor is applied to a steering device using a rack-and-pinion type steering gear, the configuration becomes complicated and large, making it difficult to share parts with a general manual steering device. There is a problem that. That is, in a steering device using a rack and pinion type steering gear, the rotational drive of a pinion shaft connected to the steering shaft is directly converted into reciprocating motion of the rack shaft on the steered wheel side via the pinion and rack. It is something. Therefore, the shaft center of a rotary drive motor is placed in a gearbox parallel to the pinion shaft, and connected to the pinion shaft via a predetermined gear device, which makes the pinion shaft, gearbox, etc. complicated. The size increases, almost all dedicated parts are required, and the number of parts also increases. Moreover, the increased size increases the weight, requires a large installation space, limits the scope of application, and increases the overall cost of the device.

The present invention was developed in view of these circumstances, and uses a rack-and-pinion type steering gear, which allows parts to be shared with general manual steering devices, and facilitates production and parts replacement. At the same time, the configuration is simplified and smaller.
The purpose of the present invention is to provide an electric power steering device that is lightweight, makes effective use of space, and reduces costs.

The feature of this invention that achieves these objectives is that the pinion shaft is equipped with a detection device that detects displacement according to the rotational torque that should be used to steer the steering wheel, and the easy shaft is auxiliary driven in the axial direction by a linear motor. By doing so, the pinion shaft, gearbox, etc. can be made into a simple component structure similar to a manual steering device without requiring any extra structure.

An embodiment of the present invention will be described below with reference to the drawings.

A pinion 3 of a pinion shaft 2 connected to a steering shaft 1 and a rack 5 of a rack shaft 4 connected to a steering wheel side are meshed within a gear housing 6 at a predetermined torsional intersection angle θ. The rack shaft 4 is pressed against the pinion 3 by a spring device 7. The pinion shaft 2 is provided with a displacement generating means for generating an axial displacement of the pinion shaft 2 caused by the meshing of the pinion shaft 2 and the rack shaft 4 at a torsional intersection angle θ in accordance with the rotational torque for steering the steering wheel. and a centering mechanism 8 that maintains the axial displacement of the pinion shaft 2 at zero when the rotational torque for steering the steering wheel is zero, and a centering mechanism 8 that converts the axial displacement of the pinion shaft 2 into an electrical output amount. A sensor 9 is provided. That is, in the centering mechanism 8, a centering plate 10 loosely fitted to the pinion shaft 2 is held between both sides by a pair of holding members 11 fixed to the pinion shaft 2 via rolls 12, and this centering plate 10 is attached to the pinion shaft 2. It is designed to be able to move integrally with the shaft 2 in the axial direction and to rotate relative to the pinion shaft 2. The vicinity of the outer periphery of the centering plate 10 is urged by spring means 15 and 16 using compression coil springs 13 and 14 with a predetermined pressing force in both axial directions, that is, in the forward and backward directions. As a result, when the pinion shaft 2 is rotated via the steering shaft 1, that is, during a steering operation,
This pinion shaft 2 is caused to move slightly forward and backward in the axial direction by a reaction force from the rack shaft 4 caused by the torsional intersection angle θ. On the other hand, when the rotational force is removed from the steering shaft 1, that is, when the steering operation is stopped, the centering plate 10 is pressed by the spring means 15 and 16 in a direction to remove the reaction force, and the pinion shaft 2 is moved to the forward/backward neutral position. I'm trying to get it back in place. The amount of displacement of this pinion shaft 2 from its neutral position is determined by the centering plate 1.
Detection is performed by the operation of a magnetic scale 17 provided at the tip of a pin that protrudes from the spring means 15 and supports the compression coil spring 13 of one of the spring means 15. In other words, the occurrence of rotational torque for auxiliary driving is mechanically detected by the movement of the scale 17.

On the other hand, the sensor 9 is fixed together with the gear housing and extracts the mechanical displacement of the scale 17 as an electrical signal. Note that the sensor 9 is
A differential transformer type displacement meter, a magnetic scale, a non-contact type minute displacement meter, etc. can be arbitrarily applied. Moreover, the centering mechanism 8 has a pressing spring 13 and a suction spring 1 arranged alternately at six equal parts on the same circumference of the centering plate 10.
Although the sensor 9 and the scale 17 may be provided between the springs 13 and 14,
It may be provided on the opposite side to the springs 13 and 14.

This sensor 9 is connected via an amplifier 18 and a characteristic circuit 19 to a servo device 20 that generates a predetermined motor control signal. The characteristic circuit 19 adds characteristics depending on, for example, the traveling speed or the steering angle to the signal, so that the servo device 20 generates appropriate motor control signals based on various conditions.

The motor for performing the force-increasing action is the rack shaft 4.
A linear motor 21 is used as a moving element. That is, an excitation coil 23 is disposed on the inner periphery of the rack shaft housing 22, and a permanent magnet layer 24 is formed on the outer periphery of the rack shaft 4. This excitation coil 23 is connected to the servo device 20 via a lead wire 25, and a signal current based on the output of the servo device 20 causes the rack shaft 4 to move in the axial direction due to electromagnetic induction between it and the permanent magnet layer 24. It is designed to generate thrust. Note that the linear motor 21 is a DC servo type or an AC
Either a servo type or a pulse motor type can be applied. The rack shaft 4 is slidably supported by a bush 41 on the distal end side of the housing 22 via an elastic body 40.

According to such a configuration, when a steering wheel (not shown) is operated, the fact that rotational torque is generated on the pinion shaft 2 is detected by detecting the axial displacement of the pinion shaft 2 through the displacement generating means and the centering mechanism 8. The displacement of the center plate 10 can be detected as follows. Then, the displacement is converted into an electrical signal, for example, a voltage change, by the sensor 9, and is sent to the linear motor 21 via the servo device 20, etc.
The rack shaft 4, which is a mover, can be moved in a direction in which the rotational torque of the pinion shaft 2 is removed, that is, in a direction in which a predetermined auxiliary drive rotation is to be performed.

When this force-increasing action is performed, the pinion shaft 2 is returned to the axial neutral position, and at the end of steering position, the centering plate 10 is also returned to the neutral position, and the output of the sensor 9 becomes zero.
Servo control is thereby performed.

Therefore, according to the device of this embodiment, it is possible to obtain a force increasing effect with good operational responsiveness and high efficiency.

Moreover, the device configuration is only provided with a centering mechanism 8 for detecting displacement in accordance with the rotational torque to be increased on the pinion shaft 2, and a sensor 9 for electrically extracting the centering mechanism 8, and a power-increasing drive motor is provided. Since the linear motor 21 is disposed on the rack shaft 4 part away from the pinion shaft 2, the configuration of the pinion shaft 2, gearbox, etc. can be made simple and compact, almost the same as a general manual steering device. Therefore, it is clear that during production, parts replacement, etc., parts can be shared with general manual steering devices, which provides great practical advantages. Moreover, since it is so compact, unlike the conventional rotary drive type motor, the number of parts is small, the weight can be reduced, and the installation space can be reduced. Further, according to the present invention, since the steering operation torque is regarded as the pinion axial displacement generated from the rack and pinion mechanism itself, and the thrust itself is applied to the rack shaft to be auxiliary driven, a special power direction conversion device is not required. It can be configured efficiently without any problems.

In the embodiment described above, a differential transformer type device in which a magnetic scale 17 protruding from the centering plate 10 is inserted into the sensor 9 was used as a means for detecting the displacement of the centering plate 10. The means are not limited to this type, but may be of other types as described above. For example, FIG. 6 shows a system in which a gap with the centering plate 10 is directly detected by a non-contact displacement meter 29.

As described above, according to the present invention, the pinion shaft is provided with a detection device that detects displacement according to the rotational torque to be auxiliary driven, and the rack shaft is driven with increased force in the axial direction by the linear motor. As a result, the pinion shaft, gear box, etc. have a simple component structure similar to that of a manual steering device, without requiring any extra structure, so parts can be shared with general manual steering devices, making production and parts replacement easier. In addition to simplifying the structure, making it smaller and lighter, it has great practical effects such as effective use of space, lower costs, and higher efficiency.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention, in which FIG. 1 is a central vertical sectional view of the main part with some parts omitted, FIG. 2 is a plan view of the same, and FIG. Figure 2 -
A line sectional view, FIG. 4 is a - line sectional view of FIG. 3,
FIG. 5 is an enlarged view of a part of FIG. 3, and FIG. 6 is a view corresponding to FIG. 5 showing another embodiment of the present invention. 2... Pinion shaft, 3... Pinion, 4... Rack axis, 5... Rack, 8... Centering mechanism for configuring displacement generating means, 9... Sensor, 20... Servo device, 21... Linear motor.

Claims (1)

[Scope of utility model registration request] a pinion shaft connected to the steering shaft; a rack shaft connected to the steering wheel side and meshing with the pinion of the pinion shaft at a predetermined torsional intersection angle; and a centering plate rotatably fitted to the pinion shaft. a holding member fixed to the pinion shaft and rotatably restraining movement of the centering plate in the pinion shaft direction;
a displacement generating means comprising an elastic body that applies a predetermined pressing force to the movement of the centering plate in the pinion axis direction; a sensor attached to the displacement generating means and converting the displacement into an electrical output amount; a servo device that is connected to the sensor and generates a predetermined motor control signal; and a servo device that is installed on the rack shaft so as to use the servo device as a moving element; An electric power steering device comprising: a linear motor that provides a moving force in a direction that reduces