JPS62191271A - Vehicle steering control device - Google Patents

Abstract

PURPOSE:To prevent an excessive change of the current due to the abnormality of a vehicle speed sensor by continuously setting the previously set current value when the detected vehicle speed is abruptly changed. CONSTITUTION:When the vehicle speed is a predetermined value or less, the current to a solenoid valve 14 is kept at the maximum value, and the discharge oil from a pump is wholly returned to a tank. Under this condition, extension quantities of output rods of power cylinders are medium and equal, and rear wheels 18A, 18B are kept at a straight advance position. Subsequently, as the vehicle speed is increased, the current to the solenoid valve 14 is decreased, and the steering quantity of the rear wheels 18A, 18B against front wheels 17A, 17B is increased. When the detected vehicle speed is abruptly changed from the previously detected vehicle speed, the current is continuously set to the value set at a predetermined time ago.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to, for example, a power steering device or an automatic stability control device of an automobile. The present invention relates to a vehicle steering control device that controls a vehicle.

<Prior Art> Conventionally, power steering devices that generate steering assist force and automatic stability control devices that steer rear wheels when steering the front wheels detect vehicle speed based on a signal from a vehicle speed sensor.
The current value to the linear solenoid for hydraulic control is controlled according to the detected vehicle speed, thereby controlling the steering assist force and the rear wheel turning angle (see Utility Model Application No. 115106/1984).

Here, the vehicle speed sensor outputs a pulse signal synchronized with the rotation of the propulsion shaft of the vehicle, and the period of this pulse signal is measured, and the vehicle speed is detected as the reciprocal of the period. In addition, the characteristics of the current value with respect to vehicle speed are shown in Figure 6. At high vehicle speeds, the current value is decreased, and in the case of a power steering system, the steering assist force is decreased, and in the case of an automatic stability control system, the current value is decreased. , the rear wheel turning angle is increased when the front wheels are steered.

<Problems to be Solved by the Invention> However, with such conventional devices, the vehicle speed may be momentarily erroneously detected as high or low due to noise superimposed on the signal from the vehicle speed sensor or poor contact of the signal line. However, based on this, the current value may be changed momentarily and excessively.

Further, if a break occurs in the signal line of the vehicle speed sensor, the pulse signal no longer comes, so the vehicle speed may be detected as Q km/h, resulting in excessive current being supplied.

In this case, the driving conditions of the vehicle (e.g. brake switch,
Neutral switch and clutch switch are all OFF
It has a disconnection detection function that monitors the presence or absence of a pulse signal within a predetermined time (conditions) and detects a disconnection when there is no signal. When a disconnection is detected, it shifts to fail-safe processing.
In other words, the current value is fixed at a small value (fail-safe current value) that corresponds to high vehicle speeds, but until the disconnection detection function is activated, an excessive current corresponding to - instantaneous Q km / h is supplied. This is an overshoot characteristic.

In view of these conventional problems, it is an object of the present invention to make it possible to prevent instantaneous excessive changes in the current value when the vehicle speed sensor is abnormal as described above.

<Means for Solving the Problems> Therefore, as shown in FIG. 1, the present invention includes a vehicle speed detection means for detecting vehicle speed based on a signal from a vehicle speed sensor;
A vehicle steering control device comprising a current value setting means for setting a current value to a linear solenoid for vehicle steering control according to a detected vehicle speed, wherein the vehicle speed detected by the vehicle speed detection means is relative to the previously detected vehicle speed. Comparative determination means for determining whether the current value is within a predetermined range, and previous value holding for maintaining the current value set by the current value setting means at the previously set current value for a predetermined time when it is determined that the current value is outside the range. The configuration is such that a means is provided.

<Operation> In the above configuration, if the detected vehicle speed suddenly changes from the previously detected vehicle speed due to an abnormality in the vehicle speed sensor,
The comparison and determination means detects this sudden change, and the previous value holding means continues to set the previously set current value corresponding to the previously detected vehicle speed for a predetermined period of time. This prevents abnormal and excessive changes in the current value.

<Example> An embodiment of the present invention will be described below.

First, the automatic stability control system will be explained with reference to FIGS. 2 and 3.

Both ends of the rear suspension member 1, which suspends the rear axle, are connected to a chassis frame (not shown) via power cylinders 2.3.
by controlling the hydraulic pressure supplied to the respective output rods 2c and 3c.
By controlling the stroke amount of the rear axle, the rear axle is steered, thereby steering the rear wheels 18A and 18B.

The hydraulic chamber of the power cylinder 2.3 is connected to two ports sa and 5b of a spool valve 5 provided in a steering gear device 4 that is a front wheel steering mechanism.

The spool valve 5 is engaged with one end of a valve drive lever 7 that is fitted into a binion 6 formed on the steering shaft, and the other end of the valve drive lever 7 is engaged with a binion housing 8. There is.

When the steering wheel 9 is rotated, for example, in the clockwise direction in FIG.
A and 17B are steered to the right.

At this time, the pinion 6, which has received a reaction force from the road surface via the rack 10, moves to the right in FIG. The spool valve 5, which swings clockwise and engages one end of the valve drive lever 7, moves to the right in the figure.

As a result, the input port 5c communicates with the port 5b, and the port 5a communicates with the low pressure side port 5d connected to the oil tank 12.

At this time, the flow rate of the oil discharged from the oil pump 13 is controlled by a linear solenoid valve 14 made of a linear solenoid, and then the oil is controlled in a hydraulic chamber 2a on the rear side of the left power cylinder 2 and a hydraulic chamber 3b on the front side of the right power cylinder 3. and simultaneously the front hydraulic chamber 2b of the left power cylinder 2 and the rear hydraulic chamber 3a of the right power cylinder 3.
The oil stored in the tank is returned to the oil tank 12 through ports 5a and 5d.

As a result, the output rod 3C of the right power cylinder 3 is extended, and the output rod 2C of the left power cylinder 2 is retracted, so the rear suspension member 1 turns rightward in the figure, which causes the rear wheels 18A, 18B is steered to the right.

On the other hand, when the steering wheel 9 is rotated counterclockwise in FIG. 2 to steer the front wheels 17A and 17B to the left, the pinion 6 and spool valve 5 move to the left, contrary to the above, and the input cap ) 5c communicates with the port 5a, and the port 5b communicates with the low pressure side port 5e, so that the output rod 2C of the power cylinder 2 is extended, and each time the output rod 3c of the power cylinder 3 is retracted, the rear wheels 18A, 18B are connected. is also steered to the left.

Here, the linear solenoid valve 14 has a characteristic of increasing the rate at which oil discharged from the oil pump 13 is relieved to the oil tank 12 in accordance with an increase in the supply current from the control circuit 15, and the supply current is controlled by the vehicle speed sensor. The control is performed as shown in FIG. 6 in accordance with the vehicle speed detected by 16.

That is, when the vehicle speed is below a predetermined value, the current value ■ to the linear solenoid valve 14 is maintained at the maximum value, and all the oil discharged from the oil pump 13 is returned to the oil tank 12, and in this state, the power cylinder 2.3 output lot 2c, 3c
The extension amount becomes equal at an intermediate amount, and the rear wheels 18A and 18B are held in the straight-ahead position. Thereafter, as the vehicle speed increases, the current value I to the linear solenoid valve 14 decreases, and the oil flow rate supplied to one power cylinder via the spool valve 5 increases.
.

The amount of turning of the rear wheels 18A and 18B increases relative to the amount of turning of wheel 17B. In this way, as the amount of rear wheel steering is increased in the same direction as the front wheel steering direction, the turning radius of the vehicle increases and there is a tendency for understeer, and the amount of correction of tire deformation due to centrifugal force also increases. Stable maneuverability.

Next, control of the current value to the linear solenoid valve 14 according to the vehicle speed will be explained.

Referring to FIG. 4, the control circuit 15 is controlled by the CPU 21. ROM2
2 and RAM 23. The CPU 1 detects the vehicle speed based on the signal from the vehicle speed sensor 16 according to the flowchart of FIG.
Search the current data from the data table in OM22,
This current data is output to the D/A converter 24. D/A
The current data is converted into an analog voltage in the converter 24 and into a current in the next voltage-to-current converter 25, thereby controlling the current to the linear solenoid valve 14.

Next, the flowchart shown in FIG. 5 will be explained.

Note that this is executed at predetermined intervals.

First, in step 1 (denoted as Sl in the figure; the same applies hereinafter), the vehicle speed is determined based on the signal from the vehicle speed sensor 16.
Detect SP. This step 1 corresponds to the vehicle speed detection means.

Next, in step 2, the currently detected vehicle speed Vsp is compared with the previously detected and held vehicle speed V SP +, and it is determined whether the difference between them is within a predetermined value.

This step 2 corresponds to the comparison and determination means.

When l V S P V S P + l≦predetermined value, it is considered normal, and the process proceeds to step 3, where the count value C for the timer is set to O, and then, in step 4, based on the vehicle speed SP detected this time. Search for current value I from the data table. Then, in step 5, VSP is substituted for V S P +, and in step 6, the current value I is output. Here, the part of step 4 corresponds to the current value setting means.

In the determination in step 2, l VSP-VSpal
>If it is the predetermined value, proceed to step 7 and increment the count value C for the timer by 1, and then in step 8 determine whether the count value C is below the predetermined value (that is, within a predetermined time from the occurrence of the abnormality). However, if it is less than the predetermined value, the process advances to step 9 and the vehicle speed vsp that was detected last time and is held is
, the current value ■ is searched from the data table based on .

Therefore, the current value ■ in this case is held at the previous current value. Thereafter, the process proceeds to step 6, where the current value I is output. Here, the steering knob 9 corresponds to the previous value holding means.

In addition, in the case of determination in step 8, if C>predetermined value, the process proceeds to step 4, 5.6, and the currently detected vehicle speed v
A current value I is set based on sp and output.

In this embodiment, the presence or absence of an abnormality is determined by comparing the vehicle speed detected this time with the vehicle speed detected last time, but since the current value corresponds to the vehicle speed,
Instead of directly comparing vehicle speeds, the presence or absence of an abnormality may be determined by comparing a current value set based on the detected vehicle speed with a previous current value.

<Effects of the Invention> As explained above, according to the present invention, it is possible to prevent instantaneous excessive changes in the current value due to an abnormality in the vehicle speed sensor, thereby increasing safety.

[Brief explanation of drawings]

Fig. 1 is a functional block diagram showing the configuration of the present invention, Fig. 2 is a system diagram of the automatic stability control system, Fig. 3 is a sectional view of the main parts of the same, Fig. 4 is a block diagram of the control circuit, and Fig. 5 6 is a flowchart h showing control details, and FIG. 6 is a diagram showing the relationship between vehicle speed and current value. 14...Linear solenoid valve 15...Control circuit 16...Vehicle speed sensor Patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio SasashimaFigure 3Figure 4Figure 6Taisha Liao SP

Claims (1)

[Claims] A vehicle steering control device comprising a vehicle speed detecting means for detecting a vehicle speed based on a signal from a vehicle speed sensor, and a current value setting means for setting a current value to a linear solenoid for vehicle steering control according to the detected vehicle speed. , a comparison determination means for determining whether the vehicle speed detected by the vehicle speed detection means is within a predetermined range with respect to the previously detected vehicle speed, and a current value setting means for a predetermined time when it is determined that the vehicle speed is outside the range. 1. A vehicle steering control device comprising: previous value holding means for holding a current value set at a previously set current value.