JPS62120273A - Actual steering angle control device for vehicle - Google Patents

Abstract

PURPOSE:To improve drivability, by a method wherein a mechanism, changing the actual steering angle of a wheel, is controlled by a servo device, and wheels are steered so that the actual steering angle of the wheel is coincided with a desired value. CONSTITUTION:As a means which stops a hydraulic cylinder 7 being an actual steering angle varying mechanism, springs 18 and 19, stopping operation of a hydraulic cylinder 7 irrespective of operation of a servo system, e.g., control valve 20, and a delay circuit, stopping operation of the hydraulic cylinder 7 through control of fail valves 21 and 22 and a servo system, are provided. When abnormality occurs to a servo system, the springs 18 and 19 and the fail safe valves 21 and 22 are actuated to prevent rear wheels 3 and 4 from being steered to an erroneous angle. When abnormality occurs to a portion except the servo system, the delay circuit is actuated to stop the rear wheels 3 and 4 with high rigidity, resulting in the possibility to improve drivability.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an actual steering angle control device for a vehicle that properly controls the actual steering angle of a wheel, and particularly relates to an actual steering angle control device for a vehicle that has an enhanced fail-safe function. This invention relates to an actual steering angle control device.

(Prior Art) As a conventional actual steering angle control device for a vehicle, there is one disclosed in, for example, Japanese Patent Laid-Open No. 128054/1983. This conventional device uses a cylinder driven by hydraulic pressure to steer the rear wheels to an appropriate steering angle, and also moves the piston of the cylinder to the neutral position when an abnormality occurs in the control system. This is intended to be a failsafe.

(Problems to be Solved by the Invention) However, since the conventional handheld device uses a spring as the mechanism for returning the piston to the neutral position and L7,
Since the spring force of this spring becomes a load when viewed from the hydraulic system, the hydraulic pressure supplied during normal operation must be increased accordingly.

Further, when an abnormality occurs, the wheels are held in the neutral position only by the spring force of the spring described in (1) and (2), which increases compliance steer, resulting in an unfavorable condition in terms of steering stability.

(Means for solving the problem) In order to solve the second problem, the present invention uses a sensor related to driver operation or vehicle motion, and changes the actual steering angle of at least one of the front wheels or the rear wheels. an actual steering angle variable mechanism, an actual steering angle target value calculation means for determining a target value of an actual steering angle of at least one of the six front wheels or rear wheels in accordance with the detected value of the sensor, and the actual steering angle target value. and a servo device that controls the actual steering angle variable mechanism so that the actual steering angle of the wheel to be controlled matches the target value of the actual steering angle determined by the value calculation means.

Furthermore, the present invention provides the above-mentioned above-mentioned first:/su, actual steering angle "1 target value calculation means and abnormality detection means for detecting an abnormality in the servo device, and the abnormality detection means detects an abnormality in the servo device. When the
The first method to stop the operation of the iX actual steering angle variable mechanism J
When an abnormality is detected in the stop means and the abnormality detection stage 1 in the sensor well or the actual steering angle [] target value calculation means, the actuation of the actual steering angle variable mechanism [1] is controlled by the servo device. t7
ing.

(Function) During normal driving, the actual steering angle of the wheels is controlled by the L sensor, the actual steering angle η■ changing mechanism, the actual steering angle target value calculation means, and the servo device.

When an abnormality occurs in the servo system, the first operation stop means stops the operation of the actual steering angle variable mechanism regardless of the operating state of the servo device, thereby causing the wheels to rotate at an incorrect angle. Prevent being steered.

Further, when an abnormality occurs in the sensor or the actual steering angle target value calculating means, the second operation stopping means stops the operation of the actual steering angle variable mechanism under control by the servo device, so that the actual steering angle variable mechanism is stopped. It is possible to stop the operation of the actual steering angle variable mechanism with higher rigidity than when using the first operation stop means, and it is possible to suppress an increase in compliance steer and prevent a decrease in steering stability.

(Example) The configuration of one embodiment of the present invention is shown in FIG.

This embodiment shows a device for controlling the actual steering angles of the rear wheels 3 and 4. The front wheels 1.2 are steered by a steering handle and a steering device (not shown) in accordance with the steering angle of the steering handle.

Rear wheel 31. - the piston rod 10 of the hydraulic cylinder 7 with two pressure chambers 8.9 in the knuckle arm 5.6;
The tips of the piston rods 10 are connected to each other, and the displacement of this piston rod 10 steers the rear wheels 3.4.

The two hydraulic chambers 8.9 of the hydraulic cylinder 7 are connected to the oil passages 14.9.
Hydraulic oil is supplied through 15. And oil road 1
A control valve 20 is interposed at 4.15, and 2.
An oil pump 12 and an accumulator 13 generate working hydraulic pressure for adjusting the hydraulic pressure supplied to the two hydraulic chambers 8 and 9. 11 is a reservoir.

A first fail-safe valve 21 is interposed in the oil 114.15. The first fail-safe valve 21 is a normally closed electromagnetic switching valve.

The two hydraulic chambers 8 and 9 of the hydraulic cylinder 7 are also in communication with each other through an oil passage 6, and this oil passage 1G has a normal oven type second fail-safe valve 22 and an orifice 1.
7 is provided.

Furthermore, a spring 18° spring 9 is housed within the hydraulic cylinder 7 to constantly urge the piston rod 10 to a neutral position. This spring 18.19 is for rear wheel 3.4
can be maintained in a neutral state only by mechanical action.

Incidentally, the first operation stop means is constituted by the first fail-safe valve 21, the 27th fail-safe valve 22, and springs 18 and 19.

the control valve 20, the first fail-safe valve 21,
The second failsafe valve 22 is controlled by a controller 40.

This controller 40 has a configuration as shown in FIG.

Variables related to the driver's operation or vehicle motion that are input to the controller 40 include the outputs θ0, . θ2 and two vehicle speed sensors 5 that detect vehicle speed
2.55, and the output δ1 of the stroke sensor 53 which detects the displacement amount of the piston rod 10 of the hydraulic cylinder 7 as shown in FIG.

The actual steering angle target value calculation circuit 41 includes one steering angle sensor 51.
Five target values of the actual steering angles of the rear wheels 3 and 4 are determined from the output θ of the vehicle speed sensor 52 and the output vI of one of the vehicle speed sensors 52. The target value δ of the actual steering angle is the actual steering angle of the rear wheels necessary to achieve a preset target motion performance, and for example,
In order to improve turning performance when turning left or right, the rear wheels are steered in the opposite phase to the front wheels, or the ideal yaw 17
The actual steering angle of the rear wheels is determined to achieve motion characteristics such as -1. and sideslip angle.

The abnormality detection circuit 42 includes two steering angle sensors 51.54, two vehicle speed sensors 52.55, and a stroke sensor 5.
3 and the target value δ of the rear wheel actual steering angle output from the actual steering angle target value calculation circuit 41, the steering angle sensor 51, vehicle speed sensor 52, servo system, and actual steering angle target are input. An abnormality in the value calculation circuit 41 is detected.

The abnormality detection circuit 42 switches the states of the outputs A and B according to the result of the abnormality determination, and connects the two relays 43 via the two transistors Tr++ Tr*.
．． Controls ON/OFF of 44.

The abnormality detection circuit 42 determines whether δII is 2TII or not, θ, 2θa or not, r v + z v
Check the four items, ``Is it z or not?'', ``Is it d, d, ``?'', and check the results of these judgments (YES or NO).
Outputs A and B are set to high level (hereinafter referred to as “
It is determined whether to set the level (indicated by "H") or low level (indicated by "L'" hereinafter).Table 1 shows the relationship between the determination results of these check items and the outputs A and B.

In Table 1, the part indicated by "=" indicates that any state may be used.

δT, I, θ1 and θ2, vl and vt, 'TR and ■8' (This G' is the rear wheel actual steering angle calculated in the abnormality detection circuit using the same algorithm as the actual steering angle target value calculation circuit. If all of the target values (target values of Both relays 43 and 44 have their contacts closed.

When the relay 43 closes, the actual steering angle target value calculation circuit 41
A target value signal T of the rear wheel actual steering angle output from the servo amplifier 45 is supplied to the servo amplifier 45. The output signal S1 of this servo amplifier 45 is given to the control valve 20.

A signal δ8 corresponding to the actual steering angle of the rear wheels 3.4 from the stroke sensor 53 is fed back to the servo amplifier 45, and the working oil pressure to the hydraulic cylinder 7 is adjusted so that δJI ZTN. As a result, rear wheel 3
, 4 is equal to the target value ■1.

Furthermore, when the relay 44 closes, the first fail-safe valve 21 is set to "open-1," and the 27th fail-safe valve 22
is "closed", and the two hydraulic chambers 8.9 of the hydraulic cylinder 7
are communicated with the oil passages 14 and 15, and the pressure regulating action as described in item 1 becomes effective.

Next, if δ8 and 75 do not match, the servo amplifier 45
Since this means that an abnormality has occurred in the servo system including the control valve 20, the stroke sensor 53, etc., the abnormality detection circuit 42 sets the output A to "L".

As a result, the relay 44 is opened, the 17th fail safe valve 21 is "closed", and the 2nd fail safe valve 22 is "closed".
becomes “open”. Therefore, the supply of hydraulic pressure to the hydraulic cylinder 7 is stopped, and the oil passage 16 is opened, so that the hydraulic oil in the two hydraulic chambers 8 and 9 can move freely.

Therefore, the piston rod 10 has a spring 18°1
The spring force of 9 moves it to the neutral position. At this time, the action of the orifice 17 provided in the oil passage 16 causes the piston rod 10 to return gently to the neutral position, thereby preventing the actual rear wheel steering angle from changing suddenly.

In this way, when an abnormality occurs in the servo system, the operation of the servo system is stopped and the rear wheel 3.4 is held in the neutral position by the spring force of the springs 18, 19.

Therefore, the rear wheels 3, 4 are prevented from being steered to an incorrect angle. In this state, the front wheels 1.2 can be steered by operating the steering handle, so there is no problem with the steering safety of the vehicle.

Next, when an abnormality in the steering angle sensor 51.54, vehicle speed sensor 52.55, or actual steering angle target value calculation circuit 41 is detected instead of the abnormality in the servo system as described above, the abnormality detection circuit 42 Set output A to "H" and output B to "L".

As a result, the relay 44 is closed, the 17th fail-safe valve 21 is opened, and the second fail-safe valve 2
2 is "closed", and the two hydraulic chambers 8. of the hydraulic cylinder 7 are closed.
9 is communicated with oil passages 14 and 15, and the servo system becomes operable to match the target value TR.

Further, the relay 43 is open. In that case, the input terminal of the servo amplifier 45 is pulled down by the resistor R of the delay circuit 46 (second operation stopping means), so it returns to the atmosphere with the time constant of C1 of the delay circuit 46. In other words, The actual steering angle target value signal 'TR is a signal for setting the rear wheel actual steering angle to zero, that is, to bring the rear wheels to the neutral position.

For this reason, two of the hydraulic cylinders 7 are connected via the control valve 20.
Hydraulic pressure for setting the piston rod 10 to the neutral position is supplied to the two hydraulic chambers 8 and 9. At this time, a delay circuit 46 is provided before the servo amplifier 45 to delay the transmission of the target value signal. Therefore, the change in the oil pressure supplied to the hydraulic cylinder 7 becomes gradual, and it is possible to prevent the rear wheels from returning to the neutral position abruptly.

In this way, when an abnormality occurs in something other than the servo system,
Due to the spring force of the above springs 18.19, the rear wheel 3.4
At the same time, the normal servo system is used to forcibly hold the rear wheels 3.4 at the neutral position using hydraulic pressure. This makes it possible to hold the rear wheels 3 and 4 in the neutral position with higher rigidity than when using only springs 18 and 19, suppressing an increase in compliance steer and improving steering stability. .

In the above embodiment, the present invention is applied to a vehicle in which the rear wheels are steered using hydraulic cylinders. It is obvious that the present invention can similarly be applied to vehicles whose wheels are steered using electric motors or other drive devices instead of hydraulic cylinders.

(Effects of the Invention) As explained in detail above, the present invention provides the following effects during normal driving:
The actual steering angle variable mechanism that changes the actual steering angle of the wheels is controlled by a servo device, and the actual steering angle target value is determined in response to variables related to the driver's operation or vehicle motion detected by a predetermined sensor. , the wheels are steered so that the actual steering angles of the wheels to be controlled match. Thereby, the target exercise performance can be obtained.

The invention also provides a first operation that stops the operation of the actual steering angle variable mechanism, regardless of the operating state of the servo device, as a means for stopping the operation of the actual steering angle variable mechanism. It includes a stopping means and a second operation stopping means for stopping the operation of the °ζ actual steering angle variable mechanism by controlling the servo device. This may cause servo system abnormalities, and in some cases,
By plowing the first operation stop means, the wheels to be controlled are prevented from being steered to an incorrect angle, and when an abnormality occurs in a part other than the servo system, the second operation stop means is activated. By operating the means, the operation of the actual steering angle variable mechanism can be stopped with higher rigidity than the first operation stopping means,
It is possible to suppress an increase in compliance steer and prevent a decrease in steering stability.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a specific block diagram of the controller in FIG. 1. 1, 2...front wheel 3,4...rear wheel 7...
- Hydraulic cylinder (actual steering angle variable mechanism) 8.9... Hydraulic chamber 10... Piston rod 18, 19... Spring (first operation stop means) 20... Control pulp 21... No. 1 Fail safe valve (first operation stop means) 22... Second fail safe valve (first operation stop means) 40... Controller 41... Actual steering angle target value calculation circuit 42... Abnormality Detection circuit 43.44... Relay 45... Servo amplifier 46... Delay circuit (second operation stop means) 51, 54
... Steering angle sensor 52.55 ... Vehicle speed sensor 53
...Stroke sensor diagram 1

Claims (1)

[Scope of Claims] 1. A sensor that detects at least one variable related to driver operation or vehicle motion, and an actual steering angle variable mechanism that changes the actual steering angle of at least one of the front wheels or the rear wheels; Actual steering angle target value calculating means for determining a target value of an actual steering angle of at least one of the front wheels or the rear wheels in accordance with the detected value of the sensor; and the actual steering angle calculated by the actual steering angle target value calculating means. A servo device that controls the actual steering angle variable mechanism so that the actual steering angle of the wheel to be controlled matches the target value of the angle, and detects abnormalities in the sensor, the actual steering angle target value calculation means, and the servo device. a first operation for stopping the operation of the actual steering angle variable mechanism when the abnormality detection means detects an abnormality in the servo device, regardless of the operating state of the servo device; a second operation for stopping the operation of the actual steering angle variable mechanism under control of the servo device when the abnormality detection means detects an abnormality in the sensor or the actual steering angle target value calculation means; 1. An actual steering angle control device for a vehicle, comprising: a stopping means.