JPH06106945A - Damping force variable shock absorber control device - Google Patents

Abstract

PURPOSE:To provide a damping force variable shock absorber control device wherein smooth control with a small control physical disorder feeling can be performed. CONSTITUTION:Sprung part acceleration DDX from an acceleration sensor 2 and a relative displacement Y from a car height sensor 4 are read in an ECU9, to calculate a sprung part speed DX and a relative speed DY between sprung and unsprung parts. A map corrected by a signal from a car speed sensor 11 is selected, to obtain an actuator signal indicating value P based on the DX, DY by the ECU9. A variable throttle valve 114 is controlled by this calculated value, to suitably adjust damping force. In correction, by decreasing the damping force smaller in accordance with decreasing a car speed, a device can cope with a rapid change of sprung part acceleration, to improve riding comfort. Vibration damping control of attaching importance to a stable feeling is obtained by increasing the damping force in accordance with increasing of the car speed. In this way, this control device obtained smooth control by preventing generation of a control physical disorder feeling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber control device capable of switching damping force settings used in a vehicle.

[0002]

2. Description of the Related Art Conventionally, skyhook control is one of damping force controls for a shock absorber mounted on a vehicle. In this control, the action direction of the damping force is determined based on the sign comparison between the sprung speed and the sprung-unsprung relative speed,
Stroke (stretch / shrink) based on the sign of the relative speed at that time
Determine the direction. The control is such that the damping force is varied according to these determination results, and the steering stability and the riding comfort are made compatible at a high level. For example, the one disclosed in Japanese Patent Laid-Open No. 3-104726 "Vehicle Suspension" is known.

[0003]

By the way, in the conventional control, since the control is performed based on the sprung speed and the sprung-unsprung relative speed, the reduction of the sprung speed is emphasized. The behavior was supposed to be controlled. At this time, even if a sudden change in sprung acceleration occurs, there is no special control. That is, the control for coping with the above change was not performed. According to such vibration suppression control, the vehicle vibration is quickly attenuated, so that the occupant does not feel fluffy, but on the other hand, the driver feels a lumpy feeling. At this time, it feels preferable when the vehicle speed is high because the sense of stability of the vehicle increases. However, when the vehicle speed is low, it suddenly pushes up from the road surface (a sudden change in sprung acceleration), and thus has a great influence on human sensitivity. That is, the vibration suppression control for the vehicle behavior causes a discontinuity of sprung acceleration (hereinafter, referred to as control uncomfortable feeling), which is a problem that an occupant feels uncomfortable.

The present invention has been made to solve the above problems, and an object thereof is to provide a damping force variable shock absorber control device capable of performing smooth control with less control discomfort. It is to be.

[0005]

The structure of the invention for solving the above-mentioned problems is to provide a shock absorber which is installed between a vehicle body and a wheel and whose damping force is variable, and a vertical sprung vibration state of the vehicle. The damping force is varied based on the sprung vibration detection means for detecting, the sprung speed guided by the sprung vibration detection means, and the sprung-unsprung relative speed which is the relative speed of the sprung speed to the unsprung speed. And a variable means for varying the damping force of the shock absorber based on the signal from the signal setting means, and the damping force of the shock absorber is controlled to control the damping force of the vehicle. A damping force variable shock absorber control device for suppressing a vibration state, comprising vehicle speed detecting means for detecting a vehicle speed, and a finger set by the signal setting means as the detected vehicle speed is lower. Characterized in that a damping force correction means for correcting such that the magnitude of the damping force based on the signal is reduced.

[0006]

According to the above means, the instruction signal for varying the damping force is set based on the sprung speed and the sprung-unsprung relative speed. Here, the magnitude of the damping force based on the instruction signal is set to be small by correction so as to cope with the case where the sprung mass acceleration changes abruptly as the vehicle speed decreases. In other words, the lower the vehicle speed, the softer the vibration with the emphasis on control discomfort, and the higher the vehicle speed, the harder the vibration suppression control with the emphasis on the feeling of stability of the vehicle.

[0007]

EXAMPLES The present invention will be described below based on specific examples. FIG. 1 is a configuration diagram showing a case where the damping force variable shock absorber control device according to the present invention is applied to a strut suspension. Between the vehicle body 1 and the unsprung member 3 connected to the wheel 7, a coil spring 6 which works so as to soften the impact from the road surface and not transmit it directly to the vehicle body, and a cylinder device which constitutes a shock absorber for damping vibration (mainly, (Cylinder 5 and piston rod 31)
Are arranged.

FIG. 3 is a sectional view showing the cylinder device. The coil spring 6 is arranged between the upper support 33 provided in the lower portion of the vehicle body 1 and the spring receiving member 38 coupled to the cylinder 5. Further, the piston rod 31 includes an upper support 33 and a cushion damper 32.
It is supported by.

A piston 31a is connected to one end of the piston rod 31, and the piston 31a is slidably arranged inside the cylinder 5. Therefore, the cylinder 5 is divided into the upper chamber 35 and the lower chamber 34 by the piston 31a. The upper chamber 35 and the lower chamber 34 are communicated with each other through a communication port 37a provided on the piston 31a. As a result, the piston 31a moves into the cylinder 5
When sliding inside, hydraulic fluid is circulated through this communication port 37a.

In addition, the pipe 3 is provided inside the piston rod 31.
6 is formed, and this pipeline 36 has a communication port 37c.
To the lower chamber 34, and to the upper chamber 35 via a communication port 37b. As shown in FIG. 1, this pipe line 36 is a variable throttle valve 1 provided in an oil line 39.
It is connected to the accumulator 8 via 14.

FIG. 4 is a sectional view showing the accumulator 8. At the left end of the cylinder 40, a left cap 41,
A right cap 42 is screwed to the right end. A free piston 44 is slidably arranged inside the cylinder 40. Therefore, the interior of the cylinder 40 is partitioned by the free piston 44 into a hydraulic chamber 45a and a gas chamber 45b. The stopper 43 is fixed to the left end of the cylinder 40 by a left cap 41,
The free piston 44 is restricted from sliding in the hydraulic chamber 45a direction. The hydraulic oil from the cylinder 5 is introduced into the hydraulic chamber 45a via the pipe 36 and the oil passage 39, and the gas is enclosed in the gas chamber 45b.

The accumulator 8 stores the working oil discharged from the upper and lower chambers 34 and 35 of the cylinder 5 and supplies the working oil to the upper and lower chambers 34 and 35 of the cylinder 5. That is, when the piston 31 a slides inside the cylinder 5, the piston rod 3 that moves in and out of the cylinder 5
The volume in the cylinder 5 is changed by the volume of 1. When this capacity decreases, the surplus hydraulic oil is discharged to the accumulator 8, and conversely, when the capacity increases, the shortage hydraulic oil is discharged from the accumulator 8 into the upper and lower chambers 34, 35.
Is supplied to.

The accumulator 8 serves as a gas spring due to the compression elasticity of the gas enclosed in the gas chamber 45b when the hydraulic oil flows into the hydraulic chamber 45a or flows out of the hydraulic chamber 45a. Also works. Therefore, it is possible to mitigate the hydraulic shock that accompanies the opening and closing of the variable throttle valve 114, and it is also possible to mitigate the shock when the wheel 7 rides on the protrusion. Further, as described above, in the oil passage 39 that connects the accumulator 8 and the upper and lower chambers 34, 35 of the cylinder 5, the variable throttle valve 114 that adjusts the opening area of the oil passage 39 to make the damping force variable. It is provided.

FIG. 5 is a sectional view showing the variable throttle valve 114. A bush 51 is press-fitted into the right end portion of the housing 50, and the stopper 5 is provided outside the bush 51.
It is screwed with a bolt 53 through 2. Inside the housing 50, a hollow shaft 54 pivotally supported by a bush 51 and a rotor 55 integrated with the shaft 54 are rotatably arranged. The shaft 54 and the rotor 55 are rotated by the rotating magnetic field generated by the coil 60.

Further, the wire 6 for passing a current through the coil 60
A connector block 63 is attached to the housing 50 with screws 64 in order to take out 1 to the outside. The connector block 63 is provided with a terminal 62 that is connected to the wire 61, so that an electric current can be supplied from the outside. The inside 6 of the connector block 63
A sealant is injected into the outer side 5a and the outer side 65b.

A plate 56 is provided at the left end of the housing 50.
Is press-fitted and fixed with screws. A bush 57 is press-fitted into the plate 56, and one end of the shaft 54 is rotatably supported by the bush 57. Further, the plate 56 is formed with a port 59 a communicating with the upper and lower chambers 34, 35 of the cylinder 5 and a port 59 b communicating with the accumulator 8.

The port 59a is a triangular hole 5 formed in a part of the shaft 54 through the oil ports 66a and 66b.
8 and a circular hole 67. Meanwhile, port 5
9b includes the shaft 5 through the hollow portion of the shaft 54.
4 communicates with the triangular hole 58 and the circular hole 67 formed in the nozzle 4. That is, the ports 59a and 59b are communicated with each other through the triangular hole 58 and the circular hole 67. The space 69 is filled with hydraulic oil.

Here, the outer diameter of the shaft 54 in the portion where the triangular hole 58 is provided on the side surface is set so that the outer periphery of the shaft 54 contacts the outer member 68 and can rotate in a liquid-tight state. There is. On the other hand, the outer diameter of the shaft 54 in the portion where the circular hole 67 is provided on the side surface is set smaller than the outer diameter of the portion where the triangular hole 58 is provided in the side surface. Further, the oil port 66 communicating with the port 59a
a is connected to a part of the surface of the shaft 54 having a triangular hole 58 on the side surface, and the oil port 66b is connected to a surface part of the shaft 54 having a circular hole 67 on the side surface. Is configured.

Therefore, when a rotating magnetic field is generated by the coil 60 to rotate the rotor 55, the shaft 54 is also rotated together with the rotor 55. When the position of the triangular hole 58 is changed by the rotation of the shaft 54, the opening area of the hydraulic fluid passage can be adjusted. That is, for example,
When hydraulic oil flows from port 59a to port 59b,
First, the hydraulic oil flows to the oil ports 66a and 66b. The hydraulic oil flowing into the oil port 66b has a circular hole 6 on its side surface.
7 to the surface portion of the shaft 54 where it is provided. Further, the hydraulic oil is supplied to the hollow shaft 54 through the circular hole 67.
It flows inward and reaches the port 59b.

On the other hand, the oil flowing into the oil port 66a is
If part of the triangular hole 58 is in contact with the oil port 66a, it flows into the hollow shaft 54 from that portion and reaches the port 59b. However, if the triangular hole 58 is not in contact with the oil port 66a, the hydraulic oil does not flow through the triangular hole 58. In this way, the triangular holes 5
The valve opening degree of the variable throttle valve 114 is determined according to the area of the oil port 66a which opens to the oil port 66a. However, the circular hole 67
Is normally open, so even if the triangular hole 58 is fully closed, the hydraulic oil flows to the port 59b little by little.

Further, as shown in FIG. 1, the vehicle height sensor 4 is arranged between the vehicle body 1 and the unsprung member 3 to detect the relative displacement amount between the vehicle body 1 and the unsprung member 3. , To an electronic control unit (hereinafter referred to as ECU) 9. Acceleration sensor 2
Is arranged in the lower portion of the vehicle body 1, detects vertical acceleration acting on the vehicle, and outputs it to the ECU 9. Vehicle speed sensor 11
Detects the speed of the vehicle body 1 from the rotational speed of the wheels and detects the ECU 9
Output to. The ECU 9 is a central processing unit (CPU), R
The variable throttle valve 114 is a well-known device including an OM, a RAM, etc., and is based on detection signals from the acceleration sensor 2, the vehicle height sensor 4, the vehicle speed sensor 11, and other sensor groups.
Adjust the valve opening of.

Next, the operation of the ECU 9 in the strut type suspension system having the above structure will be described. FIG. 2 is a block diagram illustrating the operation of the ECU 9. A block 110 is a block that digitally integrates a detection signal of the acceleration sensor 2 (that is, vertical acceleration acting on the vehicle) DDX. The speed DX is calculated. The sprung speed DX indicates the vibration state of the vehicle body.

On the other hand, a block 111 digitally differentiates the detection signal of the vehicle height sensor 4 [that is, the relative displacement amount of the sprung member (vehicle body) with respect to the unsprung member (wheel)] Y. In this block 111, the sprung-unsprung relative speed DY, which is the relative speed of the sprung member with respect to the unsprung member, is calculated. The sprung-unsprung relative velocity DY indicates a displacement velocity with the extending direction of the coil spring 6 being positive. Further, block 115
Is a block for selecting a target calculation map described later based on the detection signal of the vehicle speed sensor 11. The acceleration sensor 2, the vehicle height sensor 4, the block 110, and the block 111 described above form a sprung vibration detection unit. The vehicle speed sensor 11 serves as vehicle speed detecting means, and the block 115 serves as damping force correcting means. In the present embodiment, DX = dx / dt,
DY = dy / dt and DDX = d ² x / dt ² .

Next, the actuator signal instruction value calculation unit 112 which achieves the signal setting means reads the target calculation map selected in the block 115 according to the vehicle speed. or,
(DX / DY) is calculated from the sprung speed DX calculated in block 110 and the sprung-unsprung relative speed DY calculated in block 111. Then, the actuator signal instruction value P for (DX / DY) is set based on the target calculation map. As a result, the correction of the actuator signal instruction value P, which is the control target value according to the vehicle speed, is achieved. The detailed operation of the block 112 will be described later.

Subsequently, in block 113, block 1
The actuator signal instruction value P obtained by 12 is converted into the driving voltage V of the variable throttle valve 114, and this voltage V
The coil 60 of the variable throttle valve 114 (see FIG. 5)
The damping force is variably controlled by applying a current to the valve to change the valve opening of the variable throttle valve 114 and change the damping coefficient.

Next, the detailed operation of the ECU 9 will be described with reference to the flowchart of FIG. 6 showing the processing procedure of the ECU 9. First, in step 600,
Initial settings are executed. Next, in step 602, the sprung acceleration DDX is read from the acceleration sensor 2. Then, the routine proceeds to step 604, where the integration processing for the sprung mass acceleration DDX is executed to calculate the sprung mass speed DX. Next, in step 606, the relative displacement Y with respect to the unsprung portion on the spring is read from the vehicle height sensor 4. Then, the process proceeds to step 608, and the differential processing for the relative displacement Y is executed to calculate the sprung-unsprung relative speed DY.

Next, in step 610, the vehicle speed signal is read from the vehicle speed sensor 11. Then, the process proceeds to step 612, and the map for performing the target calculation is selected. In this map selection, as shown in FIG. 7, a map in which the maximum actuator signal instruction value Pmax in the actuator signal instruction value P which is the control target value is variable based on the vehicle speed Vs read in step 610 is selected. . Next, the routine proceeds to step 614, where the sprung speed DX calculated at step 604 and step 60
Actuator signal instruction value P for (DX / DY) based on the sprung-unsprung relative velocity DY calculated in 8
Is calculated. Then, after the actuator signal instruction value P is output to the block 113 in step 616,
Returning to step 602 described above, the same processing is repeatedly executed. By executing the arithmetic processing as described above, the actuator signal instruction value is corrected according to the vehicle speed, and a skyhook control system with less control discomfort can be provided.

Next, the detailed operation of the ECU 9 will be described based on the flowchart of FIG. 8 showing the processing procedure of the ECU 9. First, in step 800,
Initial settings are executed. Next, in step 802, the sprung acceleration DDX is read from the acceleration sensor 2. Then, the process proceeds to step 804, the integration process for the sprung mass acceleration DDX is executed, and the sprung mass speed DX is calculated. Next, in step 806, the relative displacement Y with respect to the unsprung portion on the spring is read from the vehicle height sensor 4. Then, the process proceeds to step 808, the differentiation process for the relative displacement Y is executed, and the sprung-unsprung relative velocity DY is calculated.

Next, in step 810, the vehicle speed signal is read from the vehicle speed sensor 11. Then, the process proceeds to step 812, where the dead zone region corresponding to the vehicle speed Vs is shown in FIG.
As shown in, the sprung speed DX and the sprung-unsprung relative speed DY are set on a coordinate plane (hereinafter referred to as DX-DY plane). The size of the dead zone is set to be wide at low speed and narrow at high speed. Next, the process proceeds to step 814, and the sprung speed DX and the sprung mass-
It is determined whether the unsprung relative speeds DY are both within the dead zone set in step 812. Step 81
When the sprung speed DX and the sprung-unsprung relative speed DY are both within the dead zone in step 4, the process proceeds to step 816, and the actuator signal instruction value Pfix that is a predetermined fixed value is set.

On the other hand, if both the sprung speed DX and the sprung-unsprung relative speed DY are not within the dead zone in step 814, the process proceeds to step 818, and in step 804, as in the first embodiment. The sprung speed DX calculated and the sprung-unsprung relative speed D calculated in step 808.
An actuator signal instruction value P for (DX / DY) based on Y and Y is calculated. After the processing in step 816 or step 818, the process proceeds to step 820, and the actuator signal instruction value Pfix or P is set to the above block 11
3 is output, the process returns to step 602 described above, and the same processing is repeatedly executed. By executing the arithmetic processing as described above, the actuator signal instruction value is corrected to Pfix or P according to the vehicle speed, and a skyhook control system with less control discomfort can be provided as in the first embodiment.

In the above-described first embodiment, the example in which the maximum actuator signal instruction value Pmax is changed according to the vehicle speed when the target calculation map is selected has been shown, but the present invention is not limited to this, and the following is set forth. The same effect can be obtained even if the correction is performed according to the vehicle speed. (1) The gradient (sensitivity) in the calculation map of the actuator signal instruction value P according to the vehicle speed is made variable as shown in FIG. (2) The maximum actuator signal instruction value Pmax and the slope in the calculation map of the actuator signal instruction value P corresponding to the vehicle speed are made variable as shown in FIG. (3) An offset is made variable as shown in FIG. 12 with respect to (DX / DY) on the horizontal axis in the calculation map of the actuator signal instruction value P corresponding to the vehicle speed.

Further, as an effect similar to that shown in FIG. 7, an actuator signal instruction value P corresponding to the vehicle speed is obtained.
Instead of selecting the calculation map of 1, the output limiter may be provided to limit the magnitude of the output according to the vehicle speed at the time of output. Also in FIG. 10, it is possible to obtain the same effect as changing the gradient by multiplying the input signal by the gain instead of selecting the calculation map of the actuator signal instruction value P according to the vehicle speed. In FIG. 11, this can also be achieved by a combination of the above-mentioned corrections at the input / output unit.

In the second embodiment, an example in which a predetermined fixed value is set in the dead zone area has been shown, but this fixed value can be varied according to the vehicle speed. Further, in the second embodiment, an example in which only the dead zone area is changed is shown.
As shown in FIG. 13, the continuous control area set around the dead zone area can be changed according to the vehicle speed.
Further, as shown in FIG. 14, the time gradient of the actuator signal instruction value P output can be changed depending on the vehicle speed.
Furthermore, similar effects can be obtained by appropriately combining the above-described embodiments and the like.

[0034]

As described above, the lower the vehicle speed, the smaller the damping force is corrected. That is, when the vehicle speed is low, the shock absorber is soft. In this case, it is possible to cope with a sudden change in sprung acceleration, so that the riding comfort is improved. When the vehicle speed is high, the shock absorber is made stiff. In this case, the damping control is performed with an emphasis on the sense of stability. In the variable damping force shock absorber control device of the present invention, since the control instruction signal is corrected according to the vehicle speed, it is possible to achieve a skyhook control system with less control discomfort.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a case where a damping force variable shock absorber control device according to a specific embodiment of the present invention is applied to a strut suspension.

FIG. 2 is a block diagram illustrating an operation of an ECU used in the apparatus of the embodiment.

FIG. 3 is a cross-sectional view showing a cylinder device used in the device of the embodiment.

FIG. 4 is a sectional view showing an accumulator used in the apparatus of the embodiment.

FIG. 5 is a sectional view showing a variable throttle valve used in the apparatus of the embodiment.

FIG. 6 is a flowchart of a first embodiment showing a calculation process of an actuator signal instruction value calculation unit of the ECU.

FIG. 7 is a map corresponding to FIG. 6, showing a relationship between (DX / DY) and an actuator signal instruction value.

FIG. 8 is a flowchart of a second embodiment showing a calculation process of an actuator signal instruction value calculation unit of the ECU.

FIG. 9 is a map corresponding to FIG. 8 showing the size of the dead zone region corresponding to the vehicle speed on the DX-DY plane.

10 is a map showing a first modified example of FIG. 7 in relation to the actuator signal instruction value with respect to (DX / DY).

11 is a map showing a second modified example of FIG. 7 in relation to the actuator signal instruction value with respect to (DX / DY).

FIG. 12 is a map showing a third modification example of FIG. 7 in relation to the actuator signal instruction value with respect to (DX / DY).

FIG. 13 is a map showing a modification of FIG. 9 showing the sizes of the dead zone area and the continuous control area corresponding to the vehicle speed on the DX-DY plane.

FIG. 14 is a map when the time gradient of the actuator signal instruction value output is changed according to the vehicle speed.

[Explanation of symbols]

 1 ... Vehicle body 2 ... Acceleration sensor 4 ... Vehicle height sensor 5 ... Cylinder 7 ... Wheel 8 ... Accumulator 9 ... ECU 31 ... Piston rod 114 ... Variable throttle valve

Claims (1)

[Claims] 1. A shock absorber which is installed between a vehicle body and a wheel and whose damping force is variable, a sprung vibration detecting means for detecting a vertical sprung vibration state of the vehicle, and the sprung vibration detecting means. Guided sprung speed,
Signal setting means for setting an instruction signal for varying the damping force based on the sprung-unsprung relative speed which is the relative speed of the sprung speed to the unsprung speed; and the shock based on the signal from the signal setting means. A damping force variable shock absorber control device having a varying means for varying the damping force of the absorber and suppressing the vibration state of the vehicle by controlling the damping force of the shock absorber, the vehicle speed detecting means for detecting the vehicle speed, And a damping force correction unit that corrects so that the magnitude of the damping force based on the instruction signal set by the signal setting unit becomes smaller as the detected vehicle speed becomes lower. Absorber control device.