JPH02310174A - Power steering device of car - Google Patents

Abstract

PURPOSE:To construct a power steering device small and light by interposing an aux. motor and a slide joint on the way of a steering shaft, and driving the aux. motor in accordance with the amount of relative rotation of this slide joint. CONSTITUTION:In a power steering device, in which the rotational motion given to a steering wheel 11 is transmitted to a steering gear box through a steering shaft 12, and thereby the front wheels are steered through a rack rod and a tie rod, a slide joint 20 and an aux. motor 30 are interposed on the way of the steering shaft 12. The slide joint 20 is constituted by coupling together a pair of sleeves 21, 21 through an elastic member 22 so as to be capable of relative rotation to the left and right within a certain extent around the middle point. The relative displacement of the two sleeves 21, 21 varying according to the steering torque given to the steering wheel 11 is sensed by a sensor 20S, and according to the result from sensing the aux. motor 30 is driven under appropriate control.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of Industry-1- This invention relates to a power steering device for an automobile for reducing the required steering force when performing a steering operation to change the direction of travel of an automobile.

BACKGROUND OF THE INVENTION Power steering devices have become widely available which make it easier and safer to drive a car by assisting a driver's steering operation.

Conventional power steering devices use C as their power source.
1. Generally, a hydraulic cylinder built into the steering gear box is used.

This hydraulic cylinder is operated by a hydraulic pump rotationally driven by the engine crankshaft, and this 71
The 41+ pressure system that connects the 11 pressure pump and the hydraulic cylinder is provided with a switching valve mechanism that opens and closes according to the driver's steering operation, thereby assisting the steering operation.

Problems to be Solved by the Invention According to the prior art, a part of the engine's output is consumed by the hydraulic pump for operating the hydraulic crank. In any case, there is a problem in that it is difficult to apply to small displacement vehicle models that do not have sufficient output power because the driving performance is degraded. In addition, the weight of the entire device, including the drive mechanism of the hydraulic pump and the complicated switching valve mechanism, and the storage space required for installation are quite large, making it difficult to accommodate light vehicles. Ta.

Therefore, an object of the present invention is to incorporate an auxiliary motor directly into the steering shaft and electrically drive the auxiliary motor to rotate, thereby eliminating the need to consume part of the engine's output and making the entire device smaller and lighter. It is an object of the present invention to provide an electric vehicle power steering device that can be used to improve the vehicle's performance.

Means for Solving the Problems The structure of the present invention to achieve the object includes a dual-shaft auxiliary motor interposed in the middle of the steering shaft;
A slip joint is provided between the auxiliary motor and the steering wheel. The gist is what you did.

Note that the output shaft of the auxiliary motor may be directly connected to the steering link shaft, or may be connected via a planetary gear system.

According to this structure, by interposing the auxiliary motor in the middle of the steering wheel shaft, the storage space required for its installation can be minimized.

The slip joint installed in the steering link shaft absorbs running vibrations transmitted from the [111 wheels] through its free play, while the auxiliary motor responds to the amount of relative rotation of the slip joint that exceeds the predetermined free play t. The steering wheel is driven in the direction of rotation of the steering wheel to assist the driver's steering operation, thereby reducing the required steering force. Note that the auxiliary motor automatically stops when the amount of relative rotation of the slip joint becomes smaller than a predetermined amount of play.

Furthermore, if the output shaft of the auxiliary motor is directly connected to the steering shaft, it can be used as a manual steering device without any problems even when the auxiliary motor is not operating, and the auxiliary motor and steering shaft can be connected via a planetary gear system. Since the connected motor can avoid high-speed rotation of the auxiliary motor, the auxiliary motor can be made smaller.

It works as shown below.

Example Examples will be described below with reference to the drawings.

A power steering device for an automobile consists of two main components: a slip joint 20 interposed in a steering shaft 12 and an auxiliary motor 30 (FIG. 1).

Is there a steering pole 11 installed at one end of the steering shaft 12? The rotational motion applied to the steering wheel 1 is transmitted to the steering gear box 13 via the steering shaft 12. The steering gear box 13 converts the rotary motion into water-soil motion of the rack rod 14,
．． 15, the traveling direction of the front wheels W, W can be changed. However, it is assumed that the rack rod 14 passes through the steering gear box 13 from side to side. The shear joint 20 and the auxiliary motor 30 are interposed in the middle of the steering shaft 2.

The slip joint 20 is made up of a pair of coupling sleeves 2 and 21 combined in a U-shape. The coupling sleeves 21.2] are connected via an elastic body 22 (Fig. 2) so as to be able to rotate within a certain range in the left and right directions around the midpoint positions N and N. When no rotational force is applied from 2 to 3, the midpoint positions NSN of the two coincide with each other.

Further, it is assumed that a predetermined amount of play d is set for the Z/R joint T-20 around the midpoint positions N and N.

In other words, when the relative rotation amount (■) between the coupling sleeves 21 and 21 is IDI<d/2, no force is transmitted between them (Fig. 3), and d/ 2≦IDI≦
When Dm, the transmitted force is proportional to the relative rotation amount, l D
When l > Dm, it is assumed that the two are directly connected. Tatami (7, Dm is the maximum allowable relative rotation amount, relative rotation h
(■ 1 code is, for example, steering wheel 11
The case where the coupling sleeve 21 on one side moves further to the right than the other side is taken as positive, and the case where it moves further to the left is taken as negative.

The slip joint 20 is provided with a sensor 20S (=J) that continuously detects the relative rotation between the coupling sleeves 21 and 21 (Fig. 2).The sensor 2O3 may be, for example, a differential transformer, A rotary encoder, sliding resistor, etc. can be used.

The auxiliary motor 30 has a rotor 30a and a stator 301:)
The output shaft 30C is directly connected to the sliding joint 20 side of the steering shaft 12 and the steering gear box 13 side via a joint member 31.31 (Fig. 1, Figure 2). Joint member 31.31
For example, a material that can absorb vibrations, such as a rubber joint, is suitable.

The output signal S1 from the sensor 2 OS is guided to the control device 40 (FIG. 1). A power source 42 is further connected to the control device 40, and a drive signal S2 is outputted from the control device 40 to the auxiliary motor 30.

Now, when the steering wheel 11 is rotated to the right, the coupling sleeve 2]- on the steering wheel 11 side of the slip joint 20 moves to the right, so the sensor 2O3
can detect the relative rotation amount at that time and output it as an output signal S1. However, sensor 2O3 is
It is assumed that the output signal S1 is not output within the range of IDI<d/2. , Therefore, the control device 40 inputs this output signal S1,
Since the corresponding drive signal S2 is output to the auxiliary motor 30, the auxiliary motor 30 rotates to the right at a rotational speed V corresponding to the relative rotation amount 2, and can assist in steering to the right. When the steering wheel 11 is rotated to the left, the rotation direction of the auxiliary motor 30 is also reversed, so that the auxiliary motor 30 can always operate to assist the driver's steering operation. Note that the front wheel W1W is the steering wheel 1-1.
When the sliding joint 20 is tilted to an angle corresponding to the rotation angle, the relative rotation of the slip joint 20 becomes IDI<d/2, so the auxiliary motor 30 also stops.

Note that the vehicle speed n is input to the control device 40, and the auxiliary motor 30
If the rotational speed V is made a function of the relative rotation ff1D of the slip joint 20 and the vehicle speed n, a so-called speed-responsive power steering device can be obtained. Furthermore, instead of the analog element that continuously detects the relative rotation i1D, the sensor 2O3 may be a digital element that simply detects IDI≧d/2.

In another embodiment, the auxiliary motor 30 can be connected to the steering shaft 12 via planetary gears 32, 32 arranged on both sides of its output shaft 30c (FIG. 4). Zunawachi,
Ring gears 30e, 30e are formed at both ends of a motor case 30d that houses the stator 3Qb, while sun gears 32a, 32a are attached to both ends of the output shaft 30c, and a plurality of planetary gears 32b, 32b are installed between them. ... is incorporated, and the steering shaft 1-2 is the planetary gear 3.
2b, 32b, . . . are connected to planetary gears 32b, 32b via carriers 32C, 32C that extract only the orbital motion of the gears 2b, 32b, . Since the planetary gear devices 32, 32 can provide a predetermined reduction ratio between the steering shaft 12 and the rotor 30a of the auxiliary motor 30, the torque of the auxiliary motor 30 can be used effectively.

In each of the embodiments described below, the auxiliary motor 30
even when the steering wheel 11 is inoperative
Since the rotation of the vehicle can be transmitted to the steering gear box 13, there is no fear that the steering function will be lost during driving, and a system with excellent safety can be constructed.

As described in detail, according to the present invention, the auxiliary motor and the slip joint are interposed in the middle of the steering shaft, and the auxiliary motor is driven according to the relative rotation amount of the slip joint. , it is possible to electrically assist steering without using a hydraulic pump or the like that consumes engine output, and by installing an auxiliary motor in series with the steering shaft, the overall size and weight are reduced. This has the advantage that it can be easily applied to small-displacement vehicles that have restrictions on engine output and interior storage space.

= 12-

[Brief explanation of the drawing]

1 to 3 show an embodiment, in which FIG. 1 is an explanatory diagram of the overall configuration, FIG. 2 is a schematic diagram of the main part configuration, and FIG. 3 is an operational line diagram of the slip joint. FIG. 4 is an enlarged sectional view of main parts showing another embodiment. d... Amount of play D... Relative rotation amount 11... Steering wheel 12... Steering shaft 20... Belly joint 30... Auxiliary motor 30C... Output shaft 32... Planetary gear Device

Claims (1)

[Claims] 1) A biaxial auxiliary motor interposed in the middle of the steering shaft, and a slip joint interposed between the auxiliary motor and the steering wheel, the auxiliary motor having a predetermined play. A power steering device for an automobile, characterized in that the steering wheel is driven in a rotating direction in response to an amount of relative rotation of the slip joint that exceeds a relative rotation amount of the slip joint. 2) The power steering device for an automobile according to claim 1, wherein the output shaft of the auxiliary motor is directly connected to the steering shaft. 3) The power steering device for an automobile according to claim 1, wherein the output shaft of the auxiliary motor is connected to the steering shaft via a planetary gear device.