JPS60148767A - Steering device for vehicles - Google Patents

Abstract

PURPOSE:To improve safety in a car drive, by setting up an extent allowable in view of safety driving as a rear wheel steering angle according to a car speed from a low speed range to a high speed one and when the rear wheel steering angle shows something an abnormal value there, stopping the rear wheel steering at once, in case of a steering device for a four-wheel steering vehicle steering the whole lot of rear wheels. CONSTITUTION:This device is provided with both a rear wheel steering signal generating part 10 producing a rear wheel steering angle alpha required for the steering stability upon operation on the basis of a detection output 100 out of a front wheel steering angle sensor and a reference signal generating device 30 producing reference signals alpha max' and alpha max being set to be commensurate to a critical value allowable in view of safety driving as the rear wheel steering angle in response to a car speed. And, in conformity with the said rear wheel steering signal alpha, an electrohydraulic servo valve 20B of a rear wheel steering device 20 is controlled, steering rear wheels 58 and 60 via a hydraulic cylinder 30D. In addition, at this time, the rear wheel steering angle alpha is compared with these reference signals alpha max' and alpha max at a rear wheel steering stop device 40, and when the rear wheel steering angle exceeds the said critical value, rear steering by the rear wheel steering device 20 is made so as to be stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention J The present invention relates to a vehicle steering system, and more particularly to a vehicle steering system suitable for use in a four-wheel steered vehicle that steers the rear wheels.

[Background of the invention]

It is desirable that the steering characteristics of a vehicle such as an automobile be maintained in a stable state at all times. For this reason, in order to improve the steering stability of a vehicle, it has been conventionally practiced to control the rear wheels with an electro-hydraulic servo system.

This system calculates the rear wheel steering angle necessary to obtain steering stability based on the front wheel steering angle when the front wheels and steering angle change due to driver operations, and adjusts the rear wheels according to this intermediate value. configured to steer. However, even with this type of system, if the electrical signal system that commands rearward steering fails, the rear wheels may be steered at a large steering angle, and if the rear wheels are steered at a large steering angle at high speeds, the vehicle may impede safe driving. 1 The adverse effects caused by such a failure can be prevented from being steered at a large steering angle at high speeds by controlling the steering angle of the rear wheels within a constant range. However, if the steering angle of the rear wheels is limited within a certain range in order to limit the large steering angle at high speeds, the rear wheels cannot be sufficiently steered at low speeds, which is safe even with a large steering angle. If the steering angle of the rear wheels is set to a range suitable for low speeds, there is a risk that the steering wheel may turn too sharply at high speeds, which may impede safe driving.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a vehicle steering system that can improve running safety and steering stability.

[Overview of the Invention] The present invention provides a rear wheel steering signal generation unit that generates a rear wheel steering signal including steering information associated with the steering angle of the rear wheels, and a rear wheel steering signal generator that generates the steering information of No. 16 by the rear wheel steering signal. a rear wheel steering device that steers the rear wheels to a steering angle according to the vehicle speed; a reference signal generator that generates a reference signal that is associated with a limit value that is permissible for safe driving as a rear wheel steering angle that corresponds to the vehicle speed; The rear wheel steering signal is compared with the reference signal, and when the rear wheel steering angle specified by the steering information of the rear wheel steering signal exceeds the limit value determined by the reference signal, the rear wheel steering by the rear wheel steering device is stopped. The above-mentioned object is achieved by a steering device for a vehicle 111+j, which is equipped with a rear wheel steering and stopping device that causes the vehicle to stop.

[Embodiments of the Invention] Preferred embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a 414 configuration of a preferred embodiment of the invention.

As shown in FIG. 1, the steering system in this embodiment includes a rear wheel steering signal generating section that generates a rear wheel steering signal including a steering control signal corresponding to the steering angle of the rear wheels. 10 and after l
A rear wheel steering device 2° that uses a logical steering signal to steer the rear wheels to a steering angle according to the steering information of the signal is associated with a limit value that is permissible for safe driving as a rear wheel steering angle depending on the vehicle speed. The reference signal generator 3o that generates the base signal compares the rear wheel steering signal with the reference signal and determines whether the rear wheel steering angle specified by the steering/tN signal of the rear wheel steering signal is the limit determined by the reference signal. It is comprised of a rear wheel steering stop device 4o that stops rear wheel steering by the rear wheel steering device 2o when the value exceeds this value.

The rear wheel steering signal generating section 10 takes in a detection output 100 from the detected front wheel steering angle height, and calculates the rear wheel steering angle necessary to improve steering stability based on this detection output 100. 37 and generates a rear wheel steering signal α according to this calculation 11a. This rear wheel steering signal α is set so that the voltage level is high when the rear wheel steering angle is widened, and the voltage level is low when the rear wheel steering angle is decreased. This rear wheel steering signal α is supplied to the rear wheel steering device 20 and the rear wheel steering stop device 40.

The rear wheel steering device 20 includes a servo amplifier 20A, an electro-hydraulic servo valve 20B, a hydraulic pump 20C1 and a hydraulic cylinder 2.
The hydraulic cylinder 20'D is connected to each rear wheel 58,600) through a connecting rod 50,52 and a knuckle arm 54,56.

The hydraulic pump 20C is driven by the engine 62, and its hydraulic system is configured such that oil generated by the operation of the hydraulic pump 20C is circulated through an electro-hydraulic servo valve 20B1 and a tank 2°. Also, Hess hydraulic servo-M'2
0B is configured to open the valve rlIL and drive the hydraulic cylinder 20D based on the signal α when the rear wheel steering No. 48 α amplified by the servo amplifier 2OA is supplied. When the hydraulic cylinder 20D is driven, the connecting rod 50.52 and the knuckle arm 54.56 move in response to this drive, and the rear wheel 58.6o is steered. The amount of steering of the rear wheel 58.60 is detected by the displacement sensor 2°F, and the detection output α1 is detected by the servo amplifier 20AK.
Supplied. Then, in the servo amplifier 20A, a comparison calculation is performed between the rear wheel steering signal α and the detection output α1 of the displacement sensor 2°F, and the rear wheel steering signal α and the detection output αl are
An electro-hydraulic drive signal is supplied from the amplifier 20A until the values match, and
The rear wheels 58.60 are steered to a steering angle of 01 rhi.

As shown in FIG. 2, the reference signal generating section 30 includes a light shielding plate 30 that rotates due to the rotational drive of the transmission.
A, a photocoupler 30B with a light shielding plate 30A inserted between the light emitter and the light receiver, and a one-shot multivibrator 30C that shapes the waveform of the output signal of the photocoupler 30H.
and Buxn harmodulation which converts the output signal of the one-shot multivibrator 30C into a voltage signal corresponding to the number of pulses: y(Pu1se 'Numbe
rModulation) demodulation circuit 30D, the output signal αma of the PNM demodulation circuit j1330D
x, -αmax are supplied to the rear wheel steering □stop device 40. The reference signal generator 30 generates a pulse corresponding to the rotation of the light shielding plate 30λ when the light shielding plate 30A rotates according to the rotation ratio and force of the transmission.
is output from. This output pulse is shaped and supplied to the PNMg adjustment circuit 30D.

Since the one-shot multivibrator 30C outputs a pulse signal according to the vehicle speed, this pulse 16
The PNM demodulator 77, 30D outputs a signal whose voltage level changes according to the number of pulses. The signal is a reference signal αm that corresponds to the limit value allowed for safe driving, such as the rear wheel steering angle depending on the vehicle speed.
It is output as axi −αmax. This signal has a voltage value with a small absolute value at high speeds, a voltage value with a large absolute value at low speeds, and the absolute value of the voltage value changes continuously from small to large from high speeds to low speeds. Then, these reference signals αmax, -αn1ax are applied to the rear wheel steering and stopping device 4.
0. □ The rear wheel steering and stopping device 40 includes comparators 40A, 40B, NA
ND gate 40C1 drive circuit 40D, solenoid 40g
, switch 40F, and switch 40F.
is inserted into path No. 18 between the servo amplifier 20A and the return air hydraulic servo valve 20B.

Comparator 40A uses reference signal αma'x and rear wheel steering No. 46 α.
Compare the magnitude of the voltage level of αmax)
Outputs the signal I II, and when αmax<α, the signal II
It is configured to output No. 1a of OI+. .

Further, the comparator 40B compares the voltage levels of the reference signals -αrna,,x and the rear wheel steering signal α, and calculates -αmax.
〈When α, output the signal I II, -αm a
It is configured in a circle so that it outputs a signal of "011" when x, , ) α.1.

Comparators 40A, 40B are supplied with NAND output signals.
The gate 40C determines that the output level of both the comparator 40A and the comparator 40B is II; 1. , II, that is, α or -α
The output level becomes II OI+ only when max<α<αmax, and when α is out of the range, the output level becomes T1. , I II. NA
The output level of the ND gate 40C is 111. ,,,． 11
When this happens, a drive signal is output from the drive circuit 40D to the solenoid 40E, and the switch 40F is opened. Therefore, the drive signal path supplied from the servo amplifier 20A to the hydraulic servo valve 20B is cut off. That is, the rear wheels 58, 60 can be steered by the output signal of the servo amplifier 20A only when the output level of the NAND gate 40C is 0.

In the above configuration, when the front wheels are steered, the outer wheel steering signal α corresponding to the steering angle of the front wheels is output from the rear wheel steering signal generating section 10, and the rear wheel steering device 200 operates to output the outer wheel steering signal α corresponding to the steering angle of the front wheels.
60 is steered to a steering angle sufficient to obtain steering control. This steering angle is small at high speeds (and set to a large value at low speeds, so it is possible to improve steering stability).

- The level of the rear wheel steering signal α is 1 αma,x (rear i steering by the steering device 40 is stopped. Therefore, the level of the rear wheel steering signal α is abnormal due to a failure of the rear wheel steering signal generating section 10, etc.) Even if this happens, the rear wheel steering will be stopped, increasing driving safety.

〔Effect of the invention〕

As described above in Section 44, according to the present invention, the allowable range for safe driving according to the rear wheel steering angle is set according to the vehicle speed from a low speed range to a high speed range, and the rear wheel steering angle is set in accordance with the vehicle speed. When the rear wheel steering signal to be commanded shows an abnormal value, the rear wheel steering is stopped, so stable steering characteristics can always be obtained regardless of vehicle speed, and driving safety can be improved. It has a positive effect.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the present invention, and FIG.
FIG. 2 is a specific configuration diagram of the rear wheel steering signal generation section shown in the figure. 10... Rear wheel steering signal generator 20... Rear wheel steering device 20A... Servo amplifier 20B... Electro-hydraulic servo valve 20D... Hydraulic pump 30... 2i! Quasi-1u generator 40...Rear wheel steering/stop device 40A, 40B...Comparator 40C...NAND gate 40D...Drive circuit 40E...Solenoid 40F...Switch 58,60... Rear wheel Figure 1 0 b. Figure 2 n Procedural amendment 11? (W59 2 Jl t?7 +1! I3 degr
'1 Mr. Secretary, 1982 Patent Application No. 4015 2 Name of invention Vehicle steering system 3 Supplement II: Relationship with fM Name of patent applicant (320)) Yota Motors Co., Ltd. 4 Agent Person 7, column for detailed description of the invention in the specification to be amended, column 1 for brief description of drawings in the specification, and drawings. 8. Contents of the correction (]) From the 1st line of page 7 to the 2nd line of page 8 of the specification, "The light shielding plate 30A outputs a signal." is changed to "The light shielding plate 30A emits light." A photocoupler 30B inserted between the photocoupler and the light receiving section, a one-shot multipipe rake 30C that shapes the full waveform of the output signal of the photocoupler 30B, and a one-shot multivibrator 30C that converts the output signal of the one-shot multivibrator 30C into a voltage corresponding to the number of pulses. 4 = No.K conversion t-pulse number modulation (Pu/se Number Mo
duration) demodulator 30D,
Output signals αmax, −αmax of the PNM detrainer 30D are supplied to the rear wheel steering/stop device 40. When the light shielding plate 30A rotates due to the rotational output of the transmission, the reference signal generating section 30 outputs a pulse corresponding to the rotation of the light shielding plate 30A from the photocoupler 30B. This output pulse is waveform-shaped by a one-shot mano-chip vibrator 30C and supplied to a PNM demodulation circuit 30E. Since the one-shot multi-by-break 30C outputs a signal with the number of pulses depending on the vehicle speed, this pulse signal is converted into PNM.
By demodulating with the demodulation circuit 30E, the PNM demodulation circuit 30E outputs a signal whose voltage level changes depending on the number of pulses, that is, as shown in FIG. 3, a high voltage signal at high speed and a low voltage signal at low speed. signal is output. This signal is supplied to the bias voltage application circuit 30F, and is added to the bias voltage -V shown in FIG.
The signal changes as shown in FIG. The output signal of the bias voltage application circuit 30F is output as a -αmax signal, and is also outputted as an αm signal via the polarity inversion amplifier circuit 30G.
It is output as an ax signal. Therefore, the signals supplied to the PNW demodulator 30D are output as reference signals αmax, -αmax, which are associated with the limit values allowed for safe driving as rear wheel steering angles depending on the vehicle speed. ”. (2) Listening report 1i! I 11th member 5th line to 6th line "This is a concrete configuration diagram." r concrete configuration diagram, Figure 3 is P N
FIG. 4 is a diagram of the output signal waveform of the M e %'4 circuit, FIG. 4 is a bias voltage characteristic diagram of the bias voltage application circuit, and FIG. 5 is a diagram of the output signal waveform of the bias voltage application circuit. ”. (3) Figure 2 of the drawings has been revised as shown in the attached sheet. (4) Add attached drawings 3 to 5. Above Figure 2 Figure 3 Gin □

Claims (1)

[Claims] (1) A rear wheel steering signal generation unit that generates a rear wheel steering signal including 1 steering information associated with the rear wheel steering angle, and a steering angle according to the signal 9Mk rudder information by the rear wheel steering signal. A rear wheel steering device that steers the rear wheels according to the vehicle speed, and a standard that corresponds to the limit value that is permissible for safe driving as a rear wheel steering angle depending on the vehicle speed.
Compare the reference signal generation point that generates the signal with the rear wheel steering signal and the reference signal, and when the rear wheel steering angle specified by the steering information of the rear wheel steering signal exceeds the limit value determined by the reference signal. A vehicle steering device comprising: a rear wheel steering device, and a rear wheel steering stop device for stopping steering.