JPH05193321A - Damping force control device for vehicle - Google Patents

Abstract

PURPOSE:To fully restrain generation of a sense of incongruity at control or noise in restraining an oscillating state of a vehicle using a shock absorber. CONSTITUTION:At a valve opening degree calculation part of an ECU, it is judged whether a sprung speed dX and a sprung-unsprung relative speed dY are in the same phase or not at Step 200, and when dX and dY are less than 0, it goes to step 260, where a valve opening degree P is set as a minimum valve opening degree Pmin. Also, when they are judged to be in the same phase at Step 200, it is judged from Step 210 to Step 250 whether a calculated coordinate (dY, dX) belongs to which area on a area dividing map for sprung-unsprung relative speed dY - spring upper speed dX, and the valve opening degree P is calculated according to this belonged area using a three-dimensional map constituted by a characteristic curve fA (dY, dX) to fN (dY, dX) (Step 270 to Step 320) which is set so that the opening degree at a boundary of the whole area is continuously changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force control device for a vehicle, and is used, for example, in a damping force control device for electronically controlling the damping force of a shock absorber.

[0002]

2. Description of the Related Art Conventionally, as a damping force control device for electronically controlling the damping force of a shock absorber, as an example,
There is a damping force control device that applies the so-called skyhook theory, which controls the damping force based on the sprung speed dX and the sprung-unsprung relative speed dY (relative speed between the sprung member and the unsprung member) (for example, , JP-A-3-104726). Note that dX = dx / dt and dY = dy / dt.

In this device, as shown in FIG.
Product of sprung speed dX and sprung-unsprung relative speed dY,
That is, the valve opening of the variable throttle valve that adjusts the opening area of the oil passage to change the damping force by the sign of the sprung speed dX and the unsprung-unsprung relative speed dY is the maximum valve opening P.
It is switched between max and minimum valve opening Pmin.

[0004]

However, in the above-described conventional control device, the skyhook theory for determining whether the sprung speed and the unsprung speed are in phase is applied to apply the maximum valve opening Pmax and the minimum valve opening. Since the valve opening degree of the variable throttle valve is controlled by both extreme valve opening degrees of Pmin, 3 in FIG.
As shown in the dimensional map, there is a problem that a control discomfort or noise is generated by abruptly changing the damping force from the minimum valve opening Pmin to the maximum valve opening Pmax.

Therefore, the present invention has been made in view of the above problems, and when the vibration state of the vehicle is suppressed by the shock absorber, the damping force control of the vehicle capable of suppressing the occurrence of control discomfort and noise as much as possible. The purpose is to provide a device.

[0006]

Therefore, the present invention is a vehicle damping force control device for controlling the damping force of a shock absorber in order to suppress the vibration state of the vehicle, and is installed between the vehicle body and the wheels. A shock absorber for varying the damping force, a vibration state detecting means for detecting a vertical vibration state of the vehicle, and a damping force of the shock absorber based on the vertical vibration state detected by the vibration state detecting means. In the setting, a damping force control device for a vehicle is used, which comprises: setting means for continuously and gradually variably setting the damping force as the vibration state changes.

[0007]

With the above construction, the setting means continuously and gradually changes the damping force as the vibration state changes when setting the damping force of the shock absorber based on the vertical vibration state detected by the vibration state detecting means. Is set to.

Therefore, the damping force of the shock absorber is set continuously and gradually by the setting means as the vibration state changes.

[0009]

The present invention will be described below with reference to the embodiments shown in the drawings. In this embodiment, a case where the present invention is applied to a strut type suspension will be described.

FIG. 1 is a block diagram of a strut type suspension system showing an embodiment of the present invention. In FIG. 1, a coil spring 6 is provided between the vehicle body 1 and the unsprung member 3 connected to the wheel 7 so as to soften the impact from the road surface so as not to be transmitted directly to the vehicle body, and a shock absorber for damping vibration. A cylinder device (mainly composed of the cylinder 5 and the piston 31) is arranged.

A cross-sectional view of this cylinder device is shown in FIG.
In FIG. 3, 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 connected to the cylinder 5. The piston rod 31 is supported by the upper support 33 and the cushion damper 32.

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 communicate 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 flows through this communication port 37a.

A pipe line 36 is formed inside the cylinder rod 31, and the pipe line 36 communicates with a communication port 37.
It communicates with the lower chamber 34 via c, and communicates with the upper chamber 35 via a communication port 37b.

As shown in FIG. 1, the conduit 36 is connected to the accumulator 8 via a variable throttle valve 114 provided in the oil passage 39. A cross-sectional view of this accumulator 8 is shown in FIG.

In FIG. 4, a left cap 41 is screwed to the left end of the cylinder 40, and a right cap 42 is screwed to the right end thereof. 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 portion of the cylinder 40 by a left cap 41, and the hydraulic chamber 45 a of the free piston 44.
It regulates sliding in the 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 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 in the cylinder 5, the volume in the cylinder 5 changes by the volume of the piston rod 31 that moves in and out of the cylinder 5. When this capacity decreases, the surplus hydraulic oil is discharged to the accumulator 8. On the other hand, when the capacity increases, a shortage of hydraulic oil is supplied from the accumulator 8 to the upper and lower chambers 34, 35.

The accumulator 8 has a hydraulic chamber 45a.
When hydraulic oil flows into or out of the hydraulic chamber 45a, it also functions as a gas spring due to the compression elasticity of the gas sealed in the gas chamber 45b. 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, the oil passage 3 connecting the accumulator 8 and the upper and lower chambers 34, 35 of the cylinder 5 is connected.
The valve 9 is provided with a variable throttle valve 114 that makes the damping force variable by adjusting the opening area of the oil passage 39. A sectional view of the variable throttle valve 114 is shown in FIG.

In FIG. 5, a bush 51 is press-fitted into the right end portion of the housing 50, and the outside of the bush 51 is screwed with a bolt 53 via a stopper 52. Inside the housing 50, the bush 5
A hollow shaft 54 pivotally supported by 1 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, a connector block 63 is attached to the housing 50 by screws 64 in order to take out the wire 61 for supplying a current to the coil 60 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 connector block 63
A sealing material is injected into the inner side 65a and the outer side 65b.

A plate 56 is press-fitted into the left end portion of the housing and fixed by 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 59a communicating with the upper and lower chambers 34, 35 of the cylinder 5 and a port 59b communicating with the accumulator 8.

Port 59a is connected to oil ports 66a and 6
It communicates with the triangular hole 58 and the circular hole 67 formed in a part of the shaft 54 via 6b. On the other hand, the port 59b is connected to the shaft 5 through the hollow portion of the shaft 54.
4 communicates with the triangular hole 58 and the circular hole 67. That is, the ports 59a and 59b communicate 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 at 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 a shaft 5 having a triangular hole 58 on its side surface.
4 and the oil port 66b is configured to communicate with the surface portion of the shaft 54 having a circular hole 67 on the side surface.

Therefore, when the rotating magnetic field is generated by the coil 60 and the rotor 55 is rotated, the shaft 54 is also rotated together with the rotor 55. By rotating the shaft 54 to change the position of the triangular hole 58, it is possible to adjust the opening area of the hydraulic fluid passage.

That is, for example, when the working oil flows from the port 59a to the port 59b, the working oil is first fed to the oil port 6
It flows to 6a and 66b. The hydraulic oil that has flowed into the oil port 66b has a circular hole 67 on the side surface of the shaft 5
4 to the surface part. Further, the hydraulic oil is a circular hole 67.
Through the hollow shaft 54 to reach the port 59b.

On the other hand, the oil flowing into the oil port 66a is
If a 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, the triangular hole 58 has an oil port 6
If it is not in contact with 6a, hydraulic fluid will not flow through the triangular hole 58. In this way, the triangular hole 58
The valve opening of the variable throttle valve 114 is determined according to the area of the oil port 66a that opens. However, circular hole 6
Since 7 is normally open, 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, and detects the relative displacement amount between the vehicle body 1 and the unsprung member 3. It is output to an electronic control unit (hereinafter referred to as ECU) 9. Acceleration sensor 2
Is arranged at a lower portion of the vehicle body 1, detects vertical acceleration acting on the vehicle, and outputs it to the ECU 9.

The ECU 9 includes a central processing unit (CPU), R
It is a well-known device configured by OM, RAM, etc., and adjusts the valve opening degree of the variable throttle valve 114 based on the detection signals from the acceleration sensor 2, the vehicle height sensor 4, and other sensor groups.

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. In FIG. 2, 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, and the block 110 moves the sprung member. The sprung speed dX, which is the speed, is obtained. The sprung speed dX indicates the vibration state of the vehicle body.

On the other hand, the block 111 is a block for digitally differentiating the detection signal Y of the vehicle height sensor 4 (that is, the relative displacement amount between the vehicle body and the unsprung member) Y. The sprung-unsprung relative speed dY, which is the relative speed between the upper member and the unsprung member, is obtained. The sprung-unsprung relative speed dY indicates the amount of displacement of the coil. The acceleration sensor 2, the vehicle height sensor 4, the block 110, and the block 111 described above correspond to a vibration state detecting unit. In the present embodiment, dX = dx / dt, dY = dy / dt, ddX
= D ² x / dt ² .

Then, the valve opening calculation unit 1 corresponding to the setting means
12, the sprung speed dX calculated in block 110 and the sprung-unsprung relative speed d calculated in block 111.
Based on Y, it is determined to which region on the sprung-unsprung relative speed dY-sprung speed dX region division map shown in FIG. 7 the calculated coordinate (dY, dX) belongs, and according to this belonging region Then, for example, the valve opening degree P is calculated by a three-dimensional map that is set so that the valve opening degree at the boundary of the entire region continuously changes as shown in FIG. The detailed operation of this block will be described later.

Next, in block 113, block 11
The damping force F corresponding to the valve opening degree P obtained by 2 is converted into a driving voltage V of the variable throttle valve 114, and a current is passed through the coil 60 (FIG. 5) of the variable throttle valve 114 by this voltage V. The valve opening of the variable throttle valve 7 is changed to control the damping force.

Next, the detailed operation of the above-mentioned valve opening calculation unit 112 will be described. FIG. 6 is a flowchart showing the calculation process of the valve opening degree calculation unit 112 of the ECU 9. In FIG. 6, in step 200, block 11
It is determined whether or not the product of the sprung speed dX obtained at 0 and the sprung-unsprung relative speed dY obtained at block 111 is greater than 0. This step determines whether the sprung speed dX and the unsprung speed are in phase. It is determined whether or not. And
If dX · dY is greater than 0, the process proceeds to step 210, and if dX · dY is 0 or less, step 260.
Then, the valve opening degree P is set to the minimum valve opening degree Pmin.

In steps 210 to 250, it is determined which of the areas on the sprung-unsprung relative speed dY-sprung speed dX area division map shown in FIG. 7 the calculated coordinate (dY, dX) belongs to. This is an area determination step, and steps 270 to 320 are the characteristic curves (f _A (dY, dX) to f _N (dY, d) set corresponding to the area.
X)) is a valve opening degree calculating step for calculating the valve opening degree P. Since the areas A to F and the areas I to N shown in FIG. 7 appear symmetrically, FIG. 8 shows only the three-dimensional map concerning the areas A to F and omits the three-dimensional map concerning the areas I to N. And In addition, the above-mentioned f _A (dY, d
X) to f _N (dY, dX) may be a straight line.

That is, when the calculated coordinates (dY, dX) belong to the area A or the area I (step 210), the valve opening P is calculated based on the characteristic curve f _A (step 270).
Then, when belonging to the region B or the region J (step 220), the valve opening P is calculated based on the characteristic curve f _B (step 280), and belongs to the region C or the region K (step 2).
30), the valve opening degree P is calculated based on the characteristic curve f _C (step 290), and the valve opening degree P is determined based on the characteristic curve f _D when belonging to the region D or the region L (step 240). The calculation (step 300) is performed, and the area E or the area M is calculated.
When it belongs to (step 250), the valve opening degree P is calculated based on the characteristic curve f _E (step 310), and when it does not belong to any of the above areas (that is, the area F or the area N), the characteristic curve The valve opening degree P is calculated based on f _F (step 320). In the case of the calculated coordinates (dY, dX), the region in which dX · dY is 0 or less as a result of the determination in step 200 is the region G or the region H.

That is, in the above-described embodiment, when the valve opening P is calculated from the sprung speed dX and the sprung-unsprung relative speed dY, the process of switching from the minimum valve opening Pmin to the maximum valve opening Pmax. By adopting the valve opening calculation based on the characteristic curve in (1), the valve opening can be switched continuously (gradually), and the damping force can be continuously changed as shown by the valve opening locus in FIG.

Therefore, for example, the distribution of a three-dimensional map is calculated by setting the actuator valve opening near the origin to the minimum valve opening Pmi.
n and the maximum valve opening Pmax apart from the origin, and by providing a continuous valve opening variable region based on the characteristic curve in the switching process of the minimum valve opening Pmin and the maximum valve opening Pmax, It is possible to suppress an abrupt change in the control, to reduce the occurrence of control discomfort or noise, and to reduce the vibration of the vehicle body near the sprung and unsprung resonance points.

As another example of the three-dimensional map in FIG. 8, as shown in FIG. 9, a region S in which the valve opening P is held at the minimum valve opening Pmin near the origin of the dY-dX plane. May be set. By setting this region S, it is possible to prevent extra damping force control due to sensor noise when the vehicle is stopped, and to prevent abnormal noise and vibration when the vehicle is stopped.

Next, the second embodiment will be described. In the second embodiment, as shown in the block diagram for explaining the operation of the ECU 9 in FIG. 10, the vehicle speed is input from the vehicle speed sensor 115 to the valve opening calculation unit 112 to improve the riding comfort in a wide vehicle speed range. It is what makes them.

That is, as shown in the three-dimensional map of FIG. 11, in the second embodiment, the boundary L between the valve opening calculation by the characteristic curve and the maximum valve opening Pmax is changed according to the current vehicle speed. ing. In this way, for example, when the vehicle speed is low, the boundary L is moved in a direction away from the origin, so that even if the piston speed increases at low speed due to being caught in a hole or the like, the ride comfort is not increased so much. With emphasis on, it is possible to obtain a softer riding comfort combined with a smooth feeling due to continuous change of damping force in a wide piston speed range. Further, when the vehicle speed increases, the boundary L is moved in a direction closer to the origin to positively suppress the vehicle behavior, which is combined with the smooth feeling due to the continuous change of the damping force, to improve the maneuverability. You can get a comfortable ride.

As another example of the three-dimensional map in FIG. 11, instead of the boundary L, as shown in FIG.
The maximum valve opening P _max may be changed according to the vehicle speed. That is, when the vehicle speed is low, the maximum valve opening P
It goes without saying that if _max is decreased and the maximum valve opening P _max is increased when the vehicle speed is high, the same effects as those described above can be obtained, and further, the damping force can be accurately set in all regions of dY-dX. Can be controlled.

Next, a third embodiment will be described. In the third embodiment, as shown in the block diagram for explaining the operation of the ECU 9 of FIG. 13, in addition to the vehicle speed sensor 115 described above for the valve opening calculation unit 112, the steering sensor 11
A signal (steering angle signal) from No. 6 is also input to improve the riding comfort in a wide range of vehicle speeds and also the maneuverability.

That is, as shown in FIG. 13, the valve opening calculation unit 112 defines the mapping boundary L on the front side and the rear side according to the input vehicle speed and steering angle.
The signals are moved in a direction away from the origin and a direction closer to the origin, the signals are converted into a voltage by the F / V converter 113, and then the variable throttle valves 114 and 117 on the front and rear sides are operated. . As a result, the understeer characteristic and the oversteer characteristic of the vehicle body can be tuned by the damping force control. As an example,
A front side three-dimensional map is shown in FIG. 14 (a), and a rear side three-dimensional map is shown in FIG. 14 (b).

[0044]

As described above, in the present invention, the damping force of the shock absorber is set continuously and gradually as the vibration state changes by the setting means. It is continuously and gradually changed and does not change abruptly, and when the vibration state of the vehicle is suppressed by the shock absorber, there is an excellent effect that it is possible to suppress the occurrence of control discomfort and noise as much as possible.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an operation of an ECU 9 in the above embodiment.

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

FIG. 4 is a sectional view of an accumulator 8 in the above embodiment.

FIG. 5 is a sectional view of a variable throttle valve 114 in the above embodiment.

FIG. 6 is a flowchart showing a calculation process of a valve opening calculation unit 112 of the ECU 9.

7 is a sprung-unsprung relative speed dY-sprung speed dX region division map used in the calculation process of the valve opening calculation unit 112. FIG.

8 is a three-dimensional map of sprung-unsprung relative speed dY-sprung speed dX-valve opening P used in the calculation process of the valve opening calculation unit 112. FIG.

9 is another example of a three-dimensional map of sprung-unsprung relative speed dY-sprung speed dX-valve opening P used in the calculation process of the valve opening calculation unit 112. FIG.

FIG. 10 is a block diagram illustrating an operation of an ECU 9 in the second embodiment.

FIG. 11 is a three-dimensional map of sprung-unsprung relative speed dY-sprung speed dX-valve opening P used in the calculation process of the valve opening calculation unit 112 of the ECU 9 in the second embodiment.

FIG. 12 is a valve opening calculation unit 112 according to the second embodiment.
Sprung-unsprung relative velocity dY used in the calculation process of
-Spring speed dX-It is another example of a three-dimensional map of valve opening P.

FIG. 13 is a block diagram illustrating the operation of the ECU 9 in the third embodiment.

FIG. 14 is a three-dimensional map of sprung-unsprung relative speed dY-sprung speed dX-valve opening P used in the calculation process of the valve opening calculation unit 112 of the ECU 9 in the third embodiment.

FIG. 15 is a flowchart showing a process of calculating the valve opening of a conventional variable throttle valve.

FIG. 16 is a three-dimensional map of sprung-unsprung relative speed dY-sprung speed dX-valve opening P in the conventional example.

[Explanation of symbols]

 2 Acceleration sensor 4 Vehicle height sensor 112 Valve opening calculation unit

Claims (1)

[Claims] 1. A damping force control device for a vehicle, which controls a damping force of a shock absorber in order to suppress a vibration state of the vehicle, comprising: a shock absorber installed between a vehicle body and a wheel for varying the damping force. A vibration state detecting means for detecting a vertical vibration state of the vehicle, and the vibration state changes when the damping force of the shock absorber is set based on the vertical vibration state detected by the vibration state detecting means. A damping force control device for a vehicle, comprising: setting means for continuously and gradually varying the damping force.