JPH0848257A - Power steering control device - Google Patents

Abstract

PURPOSE:To reduce the fatigue of a driver while traveling on the road between mountains by increasing the objective steering assist quantity in compliance with an increase in the degree of the severity of the road between mountains, which is detected by a means for detecting the degree of the severity of the road between mountains for reducing the force required for turning a steering wheel. CONSTITUTION:A controller 15 fetches the signals output from a car speed sensor 16 and a steering wheel angle sensor 17, as a result, input signal processing routine 18 determines car speed and a steering wheel angle and also determines lateral acceleration G. In addition, mean lateral acceleration of the lateral acceleration G is calculated. This mean lateral acceleration is applied to the map of the relation between the mean lateral acceleration and the degree of the severity of the road between mountains to determine the degree of the severity of the road between mountains. Based on this degree of the severity of the road between mountains, the characteristic line in a characteristic map indicating car speed and control current is shifted to decide the control current according to car speed. That is, when the degree of the severity of the road between mountain is high, control current is set at a higher value than that when it is low to increase steering assist quantity. An increase in steering assist quantity reduces the force required for turning a steering wheel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering control device for variably controlling a steering force of a steering wheel according to a running state of a vehicle.

[0002]

2. Description of the Related Art Some power steering control devices of this type change the steering force of a steering wheel according to the vehicle speed. The steering assist amount is increased to reduce the steering force when traveling at a low speed, and the steering assist amount is reduced to increase the steering force when traveling at a high speed.

Further, a device in which the steering force of a steering wheel is changed according to the running state of a vehicle is disclosed, for example, in Japanese Patent Publication No. 5-81467 as "a running state determination device for an automobile". . According to the present invention, it is determined whether the traveling state is urban traveling or mountain traveling, and the steering force of the steering wheel is changed according to the determination result. The steering force is lightened when the traveling state is an urban area, and the steering force is made heavy when the traveling state is a mountain road traveling.

[0004]

However, in mountain roads such as mountain roads, in general, the curves are often continuous, and the steering wheel is inevitably frequently steered. Therefore, in such a situation, if the steering force of the steering wheel is increased, the driver's fatigue may increase.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power steering control device capable of reducing driver's fatigue during traveling on a mountain road.

[0006]

A power steering control device according to the present invention comprises a steering assist amount control means for variably controlling a steering assist amount of a steering wheel of a vehicle to a target steering assist amount, and a degree to which a traveling road is a mountain road. And a mountain road degree detecting means for detecting
The steering assist amount control means increases the target steering assist amount with an increase in the detected mountain road degree.

A power steering control device according to a second aspect of the present invention comprises a vehicle speed detecting means for detecting a vehicle speed, and the steering assist amount control means decreases the target steering assist amount as the detected vehicle speed increases. To do. The power steering control device according to claim 3 is provided with a lateral acceleration detecting means for detecting a lateral acceleration acting on the vehicle from a change in a steering wheel angle, and the steering assist amount controlling means is provided with an increase in the detected lateral acceleration. The target steering assist force is reduced.

In the power steering control device according to the present invention, the mountain road degree detecting means outputs the mountain road degree based on the average value of the lateral acceleration detected by the lateral acceleration detecting means, while the output is: It is characterized in that it takes a value that increases with an increase in the average value.

[0009]

According to the power steering control device of the present invention, the steering force of the steering wheel can be reduced when traveling on a mountain road. According to the power steering control device of the second aspect, the steering force of the steering wheel can be effectively reduced during low-speed traveling, and the steering force of the steering wheel can be relatively increased during high-speed traveling.

According to the power steering control device of the third aspect, the steering force of the steering wheel can be appropriately increased when the lateral acceleration increases. Claim 4
According to the above power steering control device, the mountain road degree is obtained based on the average value of the lateral acceleration.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, there is shown a schematic configuration diagram of a power steering control device.
R is connected to a piston rod 2a of the power cylinder 2 via a tie rod 3. That is, the power cylinder 2 is composed of a double rod type hydraulic cylinder, and the other piston rod 2 of the power cylinder 2 is used.
The a is also connected to the other front wheel 1L via a tie rod 3.

The power cylinder 2 is connected to a hydraulic pressure supply source 6 via a hydraulic circuit. Here, the hydraulic pressure supply source 6 includes a hydraulic pump 7 driven by an engine 8 of the automobile, and the hydraulic pump 7 discharges the hydraulic oil sucked from the reservoir tank 14 from its discharge port. The hydraulic circuit includes a supply pipe line 101 extending from the discharge port of the hydraulic pump 7, and the supply pipe line 101 is branched into two branch pipes 102 on the downstream side of the directional control valve 5. These branch pipes 102 are respectively connected to both pressure chambers of the power cylinder 2.

The directional control valve 5 is composed of a 4-port 3-position directional control valve with throttle (actually a rotary valve), and therefore, three of the four ports have a supply line 101. And branch line 102 are respectively connected, and the remaining ports are connected to the return line 1
It is connected to the reservoir tank 14 via 03. Although not shown in detail, the switching operation of the directional control valve 5 is performed by operating the steering wheel 4,
As a result, the flow direction of the hydraulic oil supplied from the hydraulic pump 7 to the power cylinder 2 is controlled according to the operating direction of the steering wheel 4. Therefore, when the steering wheel 4 is steered, the power cylinder 2 is operated according to the steering direction, so that the steering force of the steering wheel 4 can be assisted. That is, as is well known, the piston rod 2a of the power cylinder 2 is adapted to be operated by the rack and pinion 104 which is interlocked with the operation of the steering wheel 4, and at this time, the power cylinder 2 is also operated simultaneously. Thus, the steering wheel 4 can be easily operated. When the steering wheel 4 is not operated, the directional control valve 5
Is in the neutral position, so that both pressure chambers of the power cylinder 2 are connected together via the directional control valve 5 to the low pressure side, that is, the reservoir tank 14. In FIG. 1,
The racks of the rack and pinion 104 are shown with their axes different by 90 degrees.

The power steering control system of this embodiment further comprises a steering force varying device 105 for varying the steering force (feel) of the steering wheel 4. The steering force varying device 105 includes an input shaft 4 a to which the rotation of the steering wheel 4 is input and an output shaft 1 integrally connected to the pinion gear side of the rack and pinion 104.
The hydraulic pump 7 is provided at the connecting portion between the hydraulic pump 7 and
It is designed to be operated by receiving the supply of hydraulic oil discharged from.

The input shaft 4a and the output shaft 104a of the steering wheel 4 are relatively rotatable in advance within a predetermined range, and the directional control valve is formed by the difference in the rotation angle between the input shaft 4a and the output shaft 104a. 5, the direction switching is performed. Although not shown in detail, the steering force varying device 105 includes a plurality of plungers that slide on the output shaft 104a side by hydraulic pressure, and these plungers are
Upon receiving the supply of hydraulic pressure, the input shaft 4a is pressed and the relative rotation between the input shaft 4a and the output shaft 104a is suppressed.

When the force of pressing the input shaft 4a of the plunger is strong, the degree of relative rotation between the input shaft 4a and the output shaft 104a is reduced, whereby the operation of the directional control valve 5 is suppressed. As a result, the steering force (feel) of the steering wheel 4 increases (becomes heavier). When the force pressing the input shaft 4a of the plunger is weak, the input shaft 4a
And the degree of relative rotation of the output shaft 104a is increased, which facilitates the operation of the directional control valve 5. As a result, the steering force (feel) of the steering wheel 4 is reduced (lightened).

By continuously changing the force pressing the input shaft 4a of the plunger, the steering force of the steering wheel 4 can be continuously changed. With respect to the hydraulic system of the steering force variable device 105, a branch pipe line 106 extending from the middle of the supply pipe line 101 connecting the hydraulic pump 7 and the directional control valve 5 is connected to the hydraulic pressure supply port of the steering force variable device 105. There is. Further, an electromagnetic pressure control valve 107 is provided in the middle of the branch pipe line 106, and the hydraulic oil discharged from the hydraulic pump 7 is supplied to the steering force varying device 105 via the pressure control valve 107. It has become so. Further, the hydraulic oil supplied to the steering force varying device 105 enters the pressure chamber of the plunger, and is discharged to the return pipe 103 via the pipe (108) through the orifice (not shown).

The operating oil pressure supplied to the steering force varying device 105, that is, the pressure applied to the plunger is the pressure control valve 107.
It is adapted to be adjusted based on the control current value supplied to the solenoid 107a. The solenoid 107a of the pressure control valve 107 is electrically connected to the controller 15, and the controller 15 variably controls the control current value supplied to the solenoid 107a. The control of the pressure control valve 107 is controlled by the amount of current supplied to the solenoid 107a, but on / off of energization of the solenoid 107a may be duty controlled.

Therefore, by controlling the control current value supplied to the solenoid 107a of the pressure control valve 107,
The steering force of the steering wheel 4 can be variably controlled. When the control current value supplied to the solenoid 107a is the maximum, the pressure control valve 107 is closed, the operating oil pressure is not supplied to the steering force varying device 105, and the input shaft 4
a and the output shaft 104a rotate relative to each other without resistance. As a result, the directional control valve 5 operates normally, so that the power cylinder 2 also operates normally and the steering wheel 4 operates.
The steering force is light.

When the control current value supplied to the solenoid 107a decreases, the valve opening amount of the pressure control valve 107 increases according to the decrease in the control current value, and the operating hydraulic pressure supplied to the steering force varying device 105 is increased. Is increased, and relative rotation between the input shaft 4a and the output shaft 104a is suppressed. As a result, the operation of the directional control valve 5 is suppressed, so that the operation of the power cylinder 2 is suppressed and the steering force of the steering wheel 4 becomes heavy.

The controller 15 includes a processor for executing various arithmetic processes, a memory, and an input / output circuit,
Various control programs and various data are stored in the memory. As shown in FIG. 2, the controller 15 includes a vehicle speed sensor 16 and a steering wheel angle sensor 1.
7 are connected and the respective output signals are input. The controller 15 calculates a control current value I supplied to the solenoid 107a of the pressure control valve 107 based on these output signals.

Vehicle speed sensor 16 and steering wheel angle sensor 1
The output signals of 7 are input to the input signal processing routine 18 in the controller 15, respectively. In the input signal processing routine 18, the vehicle speed is obtained based on the output signal from the vehicle speed sensor 16, and the steering wheel angle is obtained based on the output signal from the steering wheel angle sensor 17. Then, the lateral acceleration is calculated from the calculated vehicle speed and steering wheel angle. Further, in the input signal processing routine 18, the average lateral acceleration is calculated by the average lateral acceleration calculation routine based on the lateral acceleration.

The processor of the controller 15 repeatedly executes the average lateral acceleration calculation routine shown in FIG. 3 at a cycle of 100 milliseconds, for example. In each routine execution cycle, the processor reads the output signal from the vehicle speed sensor 26, inputs the vehicle speed vx, and determines whether the vehicle speed vx exceeds a predetermined vehicle speed (for example, 10 km / h) (step S1). If the determination result in step S1 is affirmative, step S2 is executed. Then, if the determination result in step S1 is negative, the process in the current cycle ends.

In step S2, the output signal from the vehicle speed sensor 26 representing the vehicle speed vx and the output signal from the steering wheel angle sensor 16 representing the steering wheel angle steera are read and expressed as a function of the vehicle speed vx with reference to a map (not shown). Done 1
The predetermined steering wheel angle gygain that gives the lateral acceleration of (G) is
Calculated based on the vehicle speed vx. Next, the processor calculates the lateral acceleration gy by dividing the steering wheel angle steera by the predetermined steering wheel angle gygain, and the calculated lateral acceleration gy is calculated by the arithmetic expression “gy”.
= Abs (gy) -0.1 ". The lateral acceleration gy is slightly reduced by this arithmetic expression. In addition, abs
(Gy) indicates the absolute value of gy.

Then, the 8 built in the controller 10
Stored values of one cumulative lateral acceleration register gysum [jj] (jj =
The lateral acceleration gy is added to each of 0 to 7). further,
The value 1 is added to the timer variable count to update the timer variable. In step S3, it is determined whether or not the value of the timer variable count is "80", and if the determination result is negative, the process in this cycle is ended.

Therefore, one cumulative lateral acceleration register
In gysum [jj], the lateral acceleration value is added over 8 seconds. 8 after starting this routine
If the determination result in step S3 becomes affirmative after the lapse of seconds, the timer variable count is reset to "0". Then, the sum of the cumulative lateral acceleration register values gysum [i] (i = 0, 7) divided by "8" is the average lateral acceleration for 64 seconds.
Calculated as gyave. Then, the index jj is updated by adding "1" to the index jj every 8 seconds.

In step S5, it is determined whether or not the updated index jj is "8". If the determination result is negative, the cumulative lateral acceleration register value at the updated index jj
The value of gysum [jj] is reset to "0" (step S
7) Then, the processing in this cycle ends. Step S5
If the determination is positive, that is, the value of the index jj is reset to "0" every 64 seconds (step S6).

As described above, the calculated lateral acceleration gy is 100 for each of the eight accumulated lateral acceleration register values gysum [jj].
It is added every millisecond, and one of the eight accumulated lateral acceleration registers gysum [jj] is updated every eight seconds, and 64 seconds worth is calculated from the eight accumulated lateral acceleration registers gysum [jj] (jj = 0, 7). As an average, the average acceleration gyave is calculated every 8 seconds.

Based on the average lateral acceleration gyave calculated by the above-described average lateral acceleration calculating routine, the mountain road degree is derived from the characteristic map showing the relationship between the average lateral acceleration and the mountain road degree shown in FIG. The average lateral acceleration gyave is "0
1G ”, and the degree of mountain road is the average lateral acceleration gyave
Takes a value of "0-100%" in proportion to. That is, as the average lateral acceleration gyave increases, the mountain road degree also increases.

Based on the mountain road degree thus calculated, the characteristic line in the characteristic map showing the relationship between the vehicle speed and the control current I shown in FIG. 5 is shifted. When the degree of mountain road is "0%", the control current value I with respect to the vehicle speed is determined based on the characteristic line shown by the solid line. Mountain road degree is "1"
When it is "00%", the control current value I with respect to the vehicle speed is determined based on the characteristic line indicated by the broken line. Further, when the value of the mountain road degree is located between “0%” and “100%”, the control current value with respect to the vehicle speed is based on the characteristic line virtually shown between the solid line and the broken line in the figure. I is determined.

According to the characteristic map of FIG. 5, the control current value I is reduced as the vehicle speed increases. Further, when the vehicle speeds are the same, the control current value I is set to a higher value when the mountain road degree is higher than when it is low. Therefore, when the vehicle speed increases, the control current value I decreases and the steering assist amount decreases, so that the steering force of the steering wheel becomes heavy. Further, as the degree of the mountain road increases, the control current value I is increased even at the same vehicle speed, so that the steering assist amount is increased and the steering force of the steering wheel is reduced. Therefore, when traveling on a mountain road, the steering force of the steering wheel is lightened, and the driver's fatigue can be reduced.

The control current value I calculated by the above calculation
Is corrected based on the following arithmetic expression. I ′ = I−Igy × Kvx In this arithmetic expression, I (A) is a control current, I ′ (A) is a correction control current, Igy (A) is a lateral acceleration control current, and Kvx is a vehicle speed correction coefficient. The control current I is obtained from the map of FIG. 5 based on the vehicle speed and the degree of mountain road.

The lateral acceleration control current Igy is obtained from the characteristic line of the characteristic map showing the relationship between the calculated lateral acceleration gy and the lateral acceleration control current value shown in FIG. The calculated lateral acceleration is calculated by multiplying the value of the lateral acceleration gy by the lateral acceleration correction coefficient obtained from the map of FIG. 7 according to the vehicle speed. According to this characteristic map, the lateral acceleration control current value Igy takes a value that proportionally increases as the calculated lateral acceleration increases. Further, the characteristic line of this characteristic map has a gentler inclination as the degree of the mountain road increases. In FIG.
When the mountain road degree is “0%”, the characteristic line is a solid line, and when the mountain road degree is “100%”, a characteristic line is a broken line. When the degree of mountain road is located between "0%" and "100%", the lateral acceleration control current value for the lateral acceleration gy is based on the characteristic line virtually shown between the solid line and the broken line in the figure. Igy is decided.

The vehicle speed correction coefficient Kvx is obtained from the characteristic line of the characteristic map showing the relationship between the vehicle speed and the vehicle speed correction coefficient shown in FIG. According to this characteristic map, the vehicle speed is "0-20".
At km / h, the vehicle speed correction coefficient takes a value of "0 to 1.0". When the vehicle speed is "20" km / h or more, the vehicle speed correction coefficient has a constant value of "1.0". Although the threshold speed is set to "20" km / h in this embodiment, it can be changed to any value.

The values of the two items (Igy × Kvx) in the above equation are particularly large when the vehicle speed is “20 km / h” or more and the lateral acceleration gy is large, for example, when the vehicle makes a sharp turn. Take a value. Therefore, when the vehicle makes a sharp turn, the correction control current I ′ is slightly reduced from the value of the control current I, and the steering assist amount is reduced accordingly, so that the steering force of the steering wheel becomes relatively heavy. , You can get a proper operation feeling.

[0036]

As described above, according to the power steering control device of the present invention, the steering force of the steering wheel is lightened as the degree of the mountain road increases, so that the vehicle can be operated while traveling on the mountain road. It is possible to reduce the fatigue of the person. According to the power steering control device of the second aspect, even when the steering force of the steering wheel is made light according to the degree of the mountain road, the steering force can be made relatively heavy at the time of high speed traveling, so that it is appropriate. A feeling of operation can be obtained.

According to the power steering control device of the third aspect, even when the vehicle is traveling on a mountain road, when the lateral acceleration increases during a sharp turn, the steering force of the steering wheel is appropriately heavy according to the lateral acceleration. Therefore, a stable operation feeling can be obtained. According to the power steering control device of the fourth aspect, it is possible to detect the degree of mountain road from the average value of the lateral acceleration by a relatively simple method, so that there is an excellent effect such as high practicality.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a power steering control device.

FIG. 2 is a system configuration diagram of a controller.

FIG. 3 is a diagram showing a flowchart of a lateral acceleration calculation routine.

FIG. 4 is a graph showing a relationship between an average lateral acceleration and a mountain road degree.

FIG. 5 is a graph showing the relationship between vehicle speed and control current.

FIG. 6 is a graph showing the relationship between calculated lateral acceleration and lateral acceleration control current amount.

FIG. 7 is a graph showing the relationship between vehicle speed and lateral acceleration correction coefficient.

FIG. 8 is a graph showing a relationship between a vehicle speed and a vehicle speed correction coefficient.

[Explanation of symbols]

 2 power cylinder 4 steering wheel 5 directional control valve 15 controller 16 vehicle speed sensor 17 steering wheel angle sensor 105 steering force varying device 107 pressure control valve

Claims (4)

[Claims] 1. A steering assist amount control means for variably controlling a steering assist amount of a steering wheel of a vehicle to a target steering assist amount, and a mountain road degree detecting means for detecting a degree to which a traveling road is a mountain road, The power steering control device, wherein the steering assist amount control means increases the target steering assist amount with an increase in the detected mountain road degree. 2. The power according to claim 1, further comprising a vehicle speed detecting means for detecting a vehicle speed, wherein the steering assist amount control means decreases the target steering assist amount as the detected vehicle speed increases. Steering control device. 3. A lateral acceleration detecting means for detecting a lateral acceleration acting on a vehicle from a change in a steering wheel angle, wherein the steering assist amount control means decreases the target steering assist amount with an increase in the detected lateral acceleration. The power steering control device according to claim 1, wherein 4. The mountain road degree detecting means outputs the mountain road degree based on an average value of lateral accelerations detected by the lateral acceleration detecting means, while the output increases with an increase in the average value. The power steering control device according to claim 1, wherein