JP3428619B2 - Vehicle damping force control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a sprung member for a vehicle.
Hydraulic shock absorber (shock) disposed between the
Damping force control system for vehicles that controls the damping force of
About the installation. [0002] 2. Description of the Related Art An example of a conventional damping force control device is, for example,
It is disclosed in JP-A-5-294122. This attenuation
The force control device adopts the so-called skyhook control theory
To control the damping force of the hydraulic shock absorber,
The relative speed between the member and the unsprung member and the vertical direction of the sprung member
The damping force is controlled based on the speed of
Vibration of the sprung member based on the vertical input from the road surface
Increases the effect of suppressing movement. [0003] In addition, in order to ensure the riding comfort of the vehicle,
The displacement speed of the piston rod that composes the hydraulic shock absorber is low.
It is desirable that the damping force be small in the region where the pressure is low. On the other hand,
To ensure good steering stability, the piston rod
It is desirable that the damping force be large in a region where the displacement speed is high.
Generally, the displacement speed of the piston rod is 0.1 to 0.3.
m / s, the damping force characteristic (change in piston rod
The slope of the characteristic that shows the relationship between damping force and position velocity)
By doing so, it is possible to achieve both ride comfort and steering stability
It is known that [0004] SUMMARY OF THE INVENTION As a result of research, the
Comfort and steering stability are not affected by the displacement speed of the piston rod.
Always low area (for example, an area of 0.02 m / s or less;
Lower, called low speed range)
I found out. [0005] However, as described above, the damping force characteristics in the low-speed range are
The vehicle's riding comfort and steering stability.
And has not been recognized in the past,
In order to improve steering stability,
It is important how the damping force characteristic is controlled. Therefore, in the present invention, in this low speed range,
By controlling the damping force characteristics, the vehicle's riding comfort and steering
To provide a vehicle damping force control device capable of further improving qualitativeness
The porpose is to do. [0007] [Means for solving the problem]Of the present inventionFor vehicles
The damping force control device is provided between the sprung member and the unsprung member of the vehicle.
Vibration occurring between them is damped with a predetermined damping force.
Region where the relative speed between the spring member and the unsprung member is low(0.
02m / s or less)Hydraulic pressure with variable damping force function
A shock-absorbing means and a hydraulic-pressure damping means,
Displacement detection to detect relative displacement between member and unsprung member
Means and relative obtained from the detection result of the displacement state detecting means
Based on the displacement direction and the change in relative displacement speed, the hydraulic pressure
Control means for controlling the damping force of the buffer means.
You. [0008] From the detection result of the displacement state detecting means, sprung
The relative displacement direction and relative displacement speed of the member and the unsprung member
An acceleration that causes a change is obtained. The control means
Based on these results, is the hydraulic buffer
Judge whether it is the contraction stroke and make the relative displacement speed
Judge whether the vehicle is accelerating or decelerating.
Perform damping force control according to the result. [0009]Of the present inventionVehicle damping force control devicesoIsFurther
ToWhen the relative displacement speed is accelerating in the control means
In the case of deceleration, increase the damping force of the hydraulic buffer
Control to reduce the damping force of the hydraulic buffer
You. The relative displacement speed is accelerated by the control means.
Increase the damping force when the vehicle is decelerating, and increase the damping force when the vehicle is decelerating.
By reducing the relative force between the sprung member and the unsprung member.
Fluctuations in displacement speed are suppressed, thereby improving the ride comfort of the vehicle.
And steering stability. [0011] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the accompanying drawings. FIG. 1 shows damping force control according to a first embodiment.
1 schematically shows a vehicle equipped with the device. Left and right of body 200
, Via the suspension arm 210, respectively
Wheels L and R are connected. Body 200 and left and right suspension
Generated on the vehicle body 200 between the pension arm 210
Shock absorber 1 for damping vertical vibration
0 is arranged. This shock absorber 10 will be
As described in FIG.
By driving and controlling the actuator 2
It is a mechanism that can adjust the damping force. Also, the steering hand
A steering shaft 202 connected to the dollar 201 has a steering hand.
A steering angle sensor 203 for detecting the operation amount of the
are doing. Further, a stroke sensor corresponding to each wheel is provided.
220 is provided, and the sensor body is fixed to the vehicle body 200
Then, the tip of the detection rod 221 extending from the sensor body is supported.
It is connected to the spence arm 210. Suspension
The detection rod 221 swings with the swing of the arm 210.
And the movement of this detection rod 221 is built into the sensor body.
It is a mechanism to detect with a potentiometer. Obedience
Therefore, the stroke sensor 220
The relative stroke amounts of the wheels L and R are detected. What
The detection rod 2 for the suspension arm 210
21 is located at a position from the center of the vehicle body 200.
The actual wheel relative stroke amount
The value is a constant multiple of the detection result of the work sensor 220. this
Therefore, a predetermined constant is added to the detection result of the stroke sensor 220.
The multiplied value is obtained as the relative stroke amount Y of the wheel. FIG. 1 schematically shows only the structure on the front wheel side.
However, the wheels L and R, shock absorber 10,
Arm 210, stroke sensor 220, etc.
Has a similar configuration on the rear wheel side. And in FIG.
As shown, an electronic control unit (hereinafter, referred to as “ECU”).
230 includes a steering angle sensor 203 and a stroke sensor for each wheel.
Vehicle speed sensor 20 for detecting the vehicle speed
4. Vertical direction acting on the vehicle body 200 as a sprung member
Such as a vertical acceleration sensor 205 that detects the acceleration of
The detection result from the sensor is given. In the ECU 230,
Based on these detection results, the following processing is executed,
Based on this calculation result, the shock absorber corresponding to each wheel
Drive control of the actuator 2 in the
ing. Here, the shock absorber 10 is described.
explain. As shown in FIG. 3, the shock absorber 10
Has a piston rod 16 and an outer cylinder 18. Outside
A guide 10a is fixed to the outer periphery of the cylinder 18, and the piston
A bracket 10b is hung on the upper end of the pad.
You. Also, between the guide 10a and the bracket 10b,
A coil spring 10c is provided.
The body is elastically supported by the spring 10c
You. Inside the outer cylinder 18, an inner cylinder 20 is provided.
And are arranged coaxially. Between the outer cylinder 18 and the inner cylinder 20
Has an annular chamber 21 formed therein. At the upper end of the outer cylinder 18
Has a rod guide 22 fitted therein. Rod guide
Reference numeral 22 denotes a columnar shape having a large diameter portion 22a and a small diameter portion 22b.
It is a rigid member. The outer peripheral surface of the small diameter portion 22b is inside the inner cylinder 20.
The outer peripheral surface of the large-diameter portion 22a is engaged with the peripheral surface of the outer cylinder 18.
Engaged with the surface. The rod guide 22 has a central part
Are provided with through holes. The through hole has a piston lock
1 is slidably inserted in a liquid-tight manner. Also outside
At the upper end of the tube 18, a cap 24 is fixed at its center.
Rod 16 is fixed so as to pass therethrough. The lower end of the piston rod 16 is small.
It is a cylindrical member having a diameter. The piston rod 16
Is arranged so that the small diameter portion of
ing. The piston rod 16 is housed inside the inner cylinder 20.
The rebound stopper 26 and the rebound
A stopper plate 28 is mounted. The rebound stopper plate 28 has an annular shape.
A rigid member fixed to the outer periphery of the piston rod 16
ing. Further, the rebound stopper 26 has elasticity.
An annular member, above the rebound stopper plate 28
Mounted on the unit. Predetermined piston rod 16 upward
When the distance is changed, the rebound stopper 26
Contact with the rod 22 and further displacement of the piston rod 16 is regulated.
Is controlled. The lower end of the piston rod 16 has a sub
The piston 30 and the main piston 32 are fixed,
From the sub piston 30 and the main piston 32
It is attached. The inner space of the inner cylinder 20 is a sub piston
30 and the main piston 32, the sub piston 30
Upper chamber 34 above, sub piston 30 and main piston
From the middle chamber 36 between the ton 32 and the main piston 32
It is partitioned into a lower chamber 38 below. Sub piston 30 and main piston 32
Are respectively between the upper chamber 34 and the middle chamber 36, and
Orifice allowing fluid to flow between the lower chamber 38 and the lower chamber 38
The piston rod 16 is provided with a
A damping force is generated according to the retreat. These sub pistons
The details of the configuration of the main piston 30 and the main piston 32 will be described later.
Will be described. The axial direction of the piston rod 16 is
A passage 40 penetrating in the opposite direction is provided. Passage 40
A large-diameter portion 40a and a small-diameter portion 4 extending below the large-diameter portion 40a
0bb. Large diameter portion 40a and small diameter of passage 40
A step 40c is formed at the boundary with the portion 40b.
You. The large diameter portion 40a of the passage 40 has an adjustment rod 42
Is inserted. A base valve 41 is provided at the lower end of the outer cylinder 18.
Fixed. The base valve 41 is annular with the lower chamber 38.
It is configured to allow fluid to flow through the chamber 21.
You. The working fluid is provided inside the outer cylinder 18 inside the inner cylinder 20.
Fill the space and fill the annular chamber 21 to the predetermined height.
It is housed as if it were cool. The upper end of the adjusting rod 42 is a piston rod
16 and was attached to the car body 200
It is engaged with the actuator 2. Actuator 2
Equipped with, for example, a stepping motor as a drive source
And adjusting rod 42 in accordance with a signal from ECU 230.
To rotate. Next, referring to FIG.
0, the configuration of the main piston 32 and its peripheral parts
Will be described. FIG. 4 shows the sub piston 30 and the main piston.
It is an enlarged view of the ton 32 and its peripheral part. The figure
4 has a fluid flow from the upper chamber 34 side to the lower chamber 38 side.
The components that allow distribution are shown, and in the right half of FIG.
Allows the fluid to flow from the lower chamber 38 side to the upper chamber 34 side
The components are shown. As shown in FIG. 4, the adjustment rod 42 is reduced.
It is one of the damping force variable mechanisms, and is a large diameter portion 40a of the passage 40.
A small-diameter portion 42a having an outer diameter smaller than the inner diameter;
And a conical portion 42b formed at the lower end portion of 42a.
I have. The adjusting rod 42 is configured such that the tip of the conical portion 42 b is
It is arranged so as to enter the small-diameter portion 40b of zero. Circle
Between the outer peripheral surface of the conical portion 42b and the step 40c of the passage 40
Is formed with a clearance C. From the small diameter portion 42a on the outer periphery of the adjusting rod 42
An O-ring 43 is mounted on the upper part. O phosphorus
The outer circumference of the small diameter portion 42a of the adjustment rod 42 is
An annular communicating air is provided between the passage 40 and the inner periphery of the large diameter portion 40a.
A gap 44 is defined. This communication space 44 is clear
Internal space of small diameter portion 40b of passage 40 via lance C
Is in communication with The piston rod 16 extends in the radial direction.
And a communication passage 46 for communicating the upper chamber 34 with the communication space 44.
Is provided. Further, the piston rod 16 has
Inside the small diameter portion 40b of the passage 40
A communication passage 47 is provided for communicating the air passage with the middle chamber 36. The adjusting rod 42 is attached to a thread (not shown).
And is screwed with the large diameter portion 40a of the passage 40,
The end is engaged with the actuator 2. For this reason,
The adjusting rod 42 is rotated by the actuator 2, and
This changes the opening position (vertical position) of the adjustment rod 42
By doing so, the clearance C can be adjusted
You. On the outer periphery of the small diameter portion of the piston rod 16
Are stored in order from the large diameter portion 16a side (the upper side in FIG. 4).
Pa plate 48, leaf seat 49, leaf valve 5
0, sub piston 30, leaf valve 54, and leaf
The seat 56 is fitted. The leaf valves 50 and 54 are made of a thin plate.
This is a member having low bending rigidity. Sub pist
The upper end face and the lower end face of the
And 60 are provided. Leaf valves 50 and 54
Are arranged to close the annular grooves 58 and 60, respectively.
Has been established. The sub-piston 30 has an annular groove 5.
8, a through passage 62 that communicates the internal space with the middle chamber 36;
And a through hole communicating the inner space of the annular groove 60 with the upper chamber 34.
A passage 64 is provided. When the hydraulic pressure in the middle chamber 36 rises, the leaf valve 50
It is higher than the hydraulic pressure in the chamber 34 by a predetermined valve opening pressure P1.
The valve opens by bending and deforming when it is
The flow of the working fluid toward 34 is allowed. Also leaf
The valve 54 is configured so that the hydraulic pressure of the upper chamber 34 is
Bends and deforms when the pressure becomes high by the predetermined valve opening pressure P2.
To open, and the working flow from the upper chamber 34 toward the middle chamber 36
Allow body flow. On the outer periphery of the sub piston 30, a piston
Ring 66 is mounted. By piston ring 66
Sealability between the sub piston 30 and the inner cylinder 20 is ensured.
Have been. Leaf sheet 5 around piston rod 16
6, a communication member 68 and a lead
Sheet 70, spacer 72, spring seat 74,
And a spacer 76 are fitted. The communication member 68 penetrates in the radial direction, and
A communication passage 77 communicating with the communication passage 47 of the ston rod 16
Have. A spring is provided around the outer periphery of the spacer 76.
A seat 78 is slidably fitted in the axial direction. S
Between the pulling seat 74 and the spring seat 78
Is provided with a spring 80. The spacer 76 on the outer periphery of the piston rod 16
Further below, is a leaf valve 82 and a
The in-piston 32 and the leaf valve 86 are fitted.
ing. The upper end surface of the main piston 32 has a plurality of seals.
A contact surface 92 is provided. Also, the main piston 32
A plurality of sheet surfaces 94 are provided on the lower surface of the
It is provided at a position that does not correspond. Leaf valve 82
And 86 are members formed by stacking a plurality of thin plate materials.
Arranged to abut the top surfaces of sheet surfaces 92 and 94, respectively
Have been. Also, a piston is provided on the outer periphery of the main piston 32.
A ton ring 95 is mounted. Piston ring 95
The seal between the main piston 32 and the inner cylinder 20
Is ensured. The main piston 32 passes through its axial direction.
Through passages 96 and 98 are provided therethrough. Through
The path 96 has a recess at its upper end between the seat surfaces 92.
At the lower end of the seat surface 94.
It is configured to talk. In addition, the through passage 98
At its upper end, it opens at the top of the seat surface 92,
At the lower end, an opening is formed in the recess between the seat surfaces 94.
Is configured. The most main pin constituting the leaf valve 82
The leaf valve 82 is seated on the thin plate material on the ston 32 side.
With the through-passage 98 and the middle chamber 36 in contact with the surface 92,
A first orifice (not shown) for communication is formed.
You. In addition, the most main pi
The leaf valve 86 has a sheet surface on the sheet material on the ton 32 side.
With the abutment 94 in contact, the through passage 96 and the lower chamber 38 are connected.
A second orifice (not shown) through which the
You. A leaf valve on the outer periphery of the piston rod 16
Spacer 99 is fitted below 86.
In addition, a screw portion 16c is provided at the lower end of the piston rod 16.
A spring seal is formed on the threaded portion 16c.
100 is screwed. The outer circumference of the spacer 99
Pulling sheet 102 is fitted slidably in the axial direction.
I have. Spring seat 102 and spring seat 10
A spring 104 is provided between the spring 104 and the spring. At the lower end of the small diameter portion of the piston rod 16
Is equipped with a screw 105 for closing the passage 40.
You. Therefore, communication between the passage 40 and the lower chamber 38 is cut off.
The passage 40 communicates only with the upper chamber 34 and the middle chamber 36.
You. Outside the small diameter portion at the lower part of the piston rod 16
The members arranged around the periphery are
To the step surface at the boundary between the large diameter portion 16a and the small diameter portion.
By being pressed, it is integrally fixed to the piston rod 16.
Have been. The leaf valves 82 and 86 have springs
By the urging forces of 80 and 104, the main piston 32
It is pressed against the top surfaces of the seat surfaces 92 and 94.
The hydraulic pressure of the lower chamber 38 is equal to the hydraulic pressure of the middle chamber 36.
When the pressure becomes higher than the predetermined valve opening pressure P3 as compared to
Flexing upward against the urging force of the ring 80
The valve is opened, and the working fluid flows from the lower chamber 38 to the middle chamber 36.
Tolerate. Further, the leaf valve 86 is provided with the liquid in the middle chamber 36.
The pressure is higher than a predetermined valve opening pressure P4 compared to the hydraulic pressure of the lower chamber 38.
When it comes to pressure, it faces downward against the biasing force of the spring 104
The valve opens by bending and deforming from the middle chamber 36 to the lower chamber 38.
Allows the flow of the working fluid to go. In this embodiment, the leaf valve 50 and the
And 54 are made of a low-rigidity thin plate member,
These valve opening pressures P1 and P2 are set to very small values.
ing. On the other hand, the leaf valves 82 and 86
By being pressed by the rings 80 and 104,
The valve opening pressures P3 and P4 are set to relatively large values.
I have. Next, the operation of the shock absorber 10 will be described.
Will be described. FIG. 5 shows the results obtained by the shock absorber 10.
4 shows the damping force characteristics to be exhibited. In FIG. 5, the horizontal axis is the pi
The vertical axis indicates the displacement speed V of the ton rod 16.
The damping force F generated by the shock absorber 10 is shown.
You. In FIG. 5, the piston rod 16 is
A field that is displaced in the direction to exit from 0, that is, in the extension direction
The combined damping force F is shown as positive. The piston rod 16 is displaced in the extension direction.
And the volume of the upper chamber 34 decreases and the volume of the lower chamber 38 decreases.
Increases. Activate to compensate for these volume changes
Fluid flows from the upper chamber 34 through the middle chamber 36 to the lower chamber 38
You. Further, the piston rod 16 retreats from the inner cylinder 20.
Thus, the volume of the inner cylinder 20 increases. Contents of this inner cylinder 20
In order to compensate for the increase in product, the working fluid
It flows into the lower chamber 38 via the one-way valve 41. When the displacement speed V of the piston rod 16 is sufficient
At low speeds, the differential pressure between the upper chamber 34 and the middle chamber 36, and
And the differential pressure between the middle chamber 36 and the lower chamber 38 is small,
The valve 54 and the leaf valve 86 are both closed.
Is held. For this reason, the working fluid in the upper chamber 34
Communication passage 46, communication space 44 of the stone rod 16, clear
Lance C, small diameter portion 40b of passage 40, communication passage 47,
And a flow path (hereinafter referred to as
(Referred to as an ipass passage), and flows into the middle chamber 36. Ma
In addition, the working fluid in the middle chamber 36 passes through the main piston 32.
Flow into the lower chamber 38 through the passage 96 and the second orifice
I do. In this case, the working fluid is supplied to the bypass passage and the second passage.
Due to distribution resistance when circulating through two orifices
A damping force is generated. The shock absorber 10 demonstrates
The damping force F causes the working fluid to flow from the upper chamber 34 to the middle chamber 36.
The damping force Fa generated according to the flow resistance R1 at the time of
Flow resistance when the moving fluid flows from the middle chamber 36 to the lower chamber 38
This is the sum with the damping force Fb generated according to R2. others
Me. As shown by reference numeral A1 in FIG. 5, the damping force F is the displacement speed.
It rises with a large gradient as V increases. The working fluid flows from the upper chamber 34 to the middle chamber 36.
When the flow resistance R1 at the time of increase, the upper chamber 34 and the middle chamber 36
And the pressure difference between them rises. Also, if the working fluid is
When the flow resistance R2 when flowing from the lower chamber 38 to the lower chamber 38 increases,
The pressure difference between the middle chamber 36 and the lower chamber 38 increases. And
The differential pressure between the upper chamber 34 and the middle chamber 36
When the displacement speed V increases until the valve opening pressure P2 is reached,
The valve 54 opens. Hereinafter, the leaf valve 54 is opened.
The displacement velocity V of the piston rod 16 and the shock
The damping force F generated by the absorber 10 is set to the first
These are referred to as a valve opening speed V1 and a first valve opening damping force F1. The above
As described above, the first valve opening damping force F1 has a very small value, for example,
The valve opening pressure of the leaf valve 54 so that the pressure becomes 3 to 5 kgf.
P2 is set sufficiently small. Like this
When the valve opening pressure P2 of the lube 54 is set, the first valve opening speed
V1 is a very low speed of 0.05 m / s or less. When the leaf valve 54 opens, the upper chamber 34
The movement of the fluid from the inner chamber 36 to
This is performed through the passage 64. For this reason,
When the working fluid flows from the upper chamber 34 toward the middle chamber 36
The flow resistance R1 decreases. And the distribution resistance R1 decreases
As a result, as shown in FIG.
In the region where the speed V exceeds the first valve opening speed V1, the damping force
The increasing slope of F decreases. The displacement speed V further increases, and the middle chamber 36 and the lower chamber 36
38 reaches the valve opening pressure P4 of the leaf valve 86
Then, the leaf valve 86 opens. Below, leaf bar
The displacement speed V and the damping force F when the valve 86 opens are determined.
The second valve opening speed V2 and the second valve opening damping force F2, respectively.
Called. In the present embodiment, the second valve opening damping force F2 is, for example,
Open the leaf valve 86 so that the pressure becomes about 50 kgf.
The pressure P4 is set. In this case, the second valve opening speed V2 is
The value is about 0.2 m / s. When the leaf valve 86 is opened, the middle chamber 36
By increasing the flow passage area of the flow passage from the lower chamber 38 to the lower chamber 38,
When the working fluid flows from the middle chamber 36 to the lower chamber 38
The flow resistance R2 decreases. For this reason, FIG.
, The displacement speed V exceeds the second valve opening speed V2.
In the region where the damping force F increases, the increasing gradient of the damping force F further decreases. On the other hand, the piston rod 16 advances to the inner cylinder 20.
In the direction of entering, that is, when displacing in the contraction direction,
As the volume of the upper chamber 34 increases, the volume of the lower chamber 38 decreases.
Less. To compensate for these volume changes, the working fluid
Flows into the upper chamber 34 from the lower chamber 38 via the middle chamber 36.
You. Further, the piston rod 16 may enter the inner cylinder 20.
Thus, the volume of the inner cylinder 20 decreases. The volume of the inner cylinder 20
In order to compensate for the product decrease, the working fluid is
It flows out into the annular chamber 21 via the valve 41. In the present embodiment, the leaf valve 50
The valve opening pressure P1 is substantially equal to the valve opening pressure P2 of the leaf valve 54.
It is provided to match. Therefore, the displacement velocity V
It reaches v1, which is almost equal to the first valve opening speed V1, and the damping force F becomes
At the time when f1 becomes substantially equal to the first valve opening damping force F1,
The leaf valve 50 opens. Also, the leaf valve 82
Is higher than the valve opening pressure P4 of the leaf valve 86.
It is provided to be slightly smaller. Because of this,
The position speed V is smaller than the second valve opening speed V2 by v2 (for example,
0.15m / s), and the damping force F becomes the second valve opening damping
F2 smaller than the force F2 (for example, about 30 kgf)
At this point, the leaf valve 82 opens. Note that
The piston lock when the leaf valves 50 and 82 are opened
The displacement speeds v1 and v2 of the arm 16 are also
These are called 1st valve opening speed and 2nd valve opening speed.
F1, which is the damping force F when the valves 50 and 82 open, and
f2 is also the first valve opening damping force and the second valve opening reduction, respectively.
It is referred to as decay. Therefore, the piston rod 16 moves in the contraction direction.
Even when the piston rod 16 is displaced,
Displacement of the piston rod 16 as in the case of displacement in the
Until the speed V reaches the first valve opening speed v1, the reference numeral in FIG.
As shown by B1, the damping force F has a relatively large gradient.
Get up with. Then, the displacement speed V becomes equal to the first valve opening speed v1.
, The leaf valve 50 is opened, and FIG.
, The increasing gradient of the damping force F is
Decrease. Further, the displacement speed V reaches the second valve opening speed v2.
Then, when the leaf valve 82 opens, the symbol in FIG.
As shown by B3, the increasing gradient of the damping force F is further reduced.
Less. As described above, according to the shock absorber 10,
For example, when the displacement speed V of the piston rod 16 is in a low speed region (first
From the valve opening speeds V1 and v1 and lower, the high speed range (first opening
(Valve speed V1, region exceeding v1)
And the damping force such that the increasing gradient of the damping force F gradually decreases.
The characteristics are realized. By the way, the opening degree of the bypass passage is clear.
It changes according to the size of the lance C. Opening the bypass passage
The greater the degree, the more the working fluid flows through the bypass passage.
, The flow resistance becomes smaller. When flowing through the bypass passage
When the flow resistance decreases, a constant displacement velocity V
The differential pressure between the slippery upper chamber 34 and the middle chamber 36 decreases, and the damping occurs.
The force F decreases. That is, in FIG.
As shown by the broken line, the slope of the damping force characteristic is small.
It becomes Therefore, adjusting the clearance C
Therefore, the displacement speed V of the piston rod 16 becomes the first valve opening speed V
1, in a region larger than v1, that is, in a high speed region
While maintaining the damping force characteristic substantially constant, the first valve opening speed V
It is possible to change the damping force characteristics at 1, v1 or less.
Wear. As described above, the first valve opening speed V1, v1 is 0.05
It is set to a low value of m / s or less. Therefore, this implementation
According to the shock absorber 10 according to the embodiment, the clearer
By changing the capacitance C, the attenuation in the high-speed region
0.05m / s or less without affecting the force characteristics
Of the damping force characteristics of the shock absorber 10 in the low speed range.
Can only be adjusted. In addition, the actuator 2
The clearance C can be changed stepwise by controlling the drive.
As a result, in the low speed range of the piston rod 16,
The gradient of the damping force characteristic of the absorber 10 is varied stepwise.
It is also possible. The shock absorber 10 according to the present embodiment
According to the experiment performed using the
Depending on the characteristics, the ride comfort and handling stability of the vehicle are large
It is known to change. For example, clearance
Decrease C to increase slope of damping force characteristics in low speed range
This will increase the steering holding force during turning.
As a result, the feeling of steering response increases. Ma
In addition, in response to changes in the damping force characteristics at low speeds,
Rolling speed of the vehicle at the time of driving and the vehicle at the time of steering
The responsiveness of both yaw changes varies sensitively. Follow
Thus, according to the shock absorber 10 according to the present embodiment,
By adjusting the clearance C, the damping force
Optimum riding comfort and driving comfort by changing
Qualitative. In each embodiment described below
Is mainly reduced by the ECU 230 in this low speed range.
Control the decay characteristics. Here, the operation is executed by the ECU 230.
Control for changing the damping force of the shock absorber 10 (damping force
Change routine) based on the flowchart of FIG.
Will be described. The flowchart of FIG. 6 is shown in FIG.
Damping Force of Shock Absorber 10 Corresponding to Wheel L
The change control is shown representatively, and the other three wheels are also controlled.
Similar damping force control is performed. The routine shown in FIG.
Between when the switch is turned on and when it is turned off.
It is repeatedly performed. First, step 100 (hereinafter, the steps are referred to as
In “S”), the shock generated by the shock absorber 10
Temporarily set the number of control steps to determine the damping force to be applied
However, the respective processes executed in S100 are described in the flowchart shown in FIG.
Explanation will be made based on the chart. First, the process proceeds to S102, where the steering angle sensor 20
3, stroke sensor 220, vertical acceleration sensor 20
4. Each section indicating the running state of the vehicle, such as a vehicle speed sensor 205,
Read the sensor detection result. At S104, the stroke sensor 22
Based on the relative stroke amount Y of the wheel L detected at 0,
The relative stroke speed of the wheel L (hereinafter referred to as the stroke speed)
Calculate Vi and mount it on the vehicle body 200.
Based on the detection result of the lower acceleration sensor 205,
The sprung speed Zd which is the speed in the direction is calculated. At S106, the value calculated at S104 is calculated.
Speed ratio Zd / stroke speed Vi and sprung speed Zd
Based on Vi and the vehicle speed read in S102, the sky
Set the number of control steps step based on hook control theory
I do. The number of control steps, step, is
Step 10 serving as a drive source of the actuator 2 in 10
To set the stopping position of the motor
Therefore, the number of control steps is equal to the number of shock absorbers 1
0 corresponds to the vertical position of the adjustment rod 42.
You. The larger the number of control steps, the larger the adjustment lock.
The clearance C of the oil passage formed by the
And the damping force increases (damping force changes to the hard side),
The smaller the number of control steps, the larger the clearance C of the oil passage
And the damping force decreases (damping force shifts to the soft side).
Mechanism. At S108, the data read at S102 is read.
The vehicle is in a turning state based on the detection result of the steering angle sensor 203.
Is determined. For example, let the detected steering angle be θ.
Then, when | θ | is larger than a predetermined turning determination constant θs
Then, it is determined that the vehicle is in a turning state. If "No" in S108 (the vehicle is
The state) includes the control step number step set in S106.
It is maintained, and S100 ends as it is. If "Yes" in S108, S11
0, and determines whether the stroke speed Vi is Vi> 0.
Set. If “Yes” is determined in S110,
The piston rod 16 of the shock absorber 10 extends.
In this case, the process proceeds to S112.
Only one step for the number of control steps set in S106.
Update the increased value as a new control step number step
You. On the other hand, if it is determined “No” in S110,
In this case, the process proceeds to S114, where the stroke speed Vi is Vi <
It is determined whether it is 0. It is determined as “No” in S114
In this case, the control step number step set in S106
Is maintained as it is, and S100 ends. At S114
If "Yes" is determined, the shock absorber
Shrinking stroke in which 10 piston rods 16 are displaced to the shrinking side
In this case, the process proceeds to S116, and is set in S106.
The value obtained by subtracting 1 step from the set number of control steps step
It is updated as the control step number step. At the time of turning of the vehicle, the turning of the vehicle
The shock absorber 10 on the outer wheel becomes the contraction stroke,
When the shock absorber 10 on the turning inner wheel side is extended,
You. Therefore, in S100, the turning inner wheel side, which is the extension stroke,
S112 for the shock absorber 10 of
Outer wheel side, which is a contraction stroke so that the damping force increases
For the shock absorber 10 of
Control step number st so that the damping force decreases
ep is set. The number of control steps step is changed in this way
The shock absorber 10 on the turning inner wheel side
The amount of elongation is suppressed, and the shock absorber 1 on the turning outer wheel side
The amount of shrinkage of 0 increases. By such action, turning
Sometimes the height of the center of gravity of the vehicle body 200 decreases, improving the maneuverability when turning.
Can be up. S100 was performed as described above.
Then, the process proceeds to S202 in FIG.
Thus, the determination flag Fc is set. Vi is the speed determination constant
If Vs or more, Fc = 1 is set, and Vi is
When the constant is equal to or less than -Vs, Fc = -1 is set, and-
When Vs <Vi <Vs, Fc = 0 is set. At S204, the acceleration dVi of the wheel L is obtained.
/ Dt is calculated. The calculated acceleration dVi / d
t is a relative acceleration between the vehicle body 200 and the wheel L.
You. In the following S206, the judgment flag Fc is set to 1
Is there, that is, the shock absorber 10
It is determined whether or not there is, and if “Yes” is determined, S2
08, the acceleration dVi of the wheel L calculated in S204
It is determined whether / dt is 0 or more. In the case where "Yes" is determined in S208,
Is a strike toward the direction of extension of the shock absorber 10.
In such a case, the roking speed Vi is in an accelerating state.
First, the process proceeds to S210, and the temporary setting is performed in this routine.
Number of control steps set in the previous routine.
Compare with the specified number of control steps step old. S21
0, the control step number step is old
If it is larger (“Yes” in S210), the process proceeds to S212.
The number of control steps temporarily set in this routine
Step is set as the number of control steps step. this
Then, the process proceeds to S214, in which the control set in this routine is performed.
The value of the number of steps step is stored as step old. one
On the other hand, when it is determined “No” in S210,
Number of control steps temporarily set in this routine step
Is the number of control steps set in the previous routine step old
In the following cases, the process proceeds to S216, where the temporarily set control mode is set.
The previous control in which the value of step number step becomes a value equal to or greater than the current value
The number of steps is replaced by step old.
Step 14 is executed. On the other hand, the determination at S208 is “No”.
In the direction of extension of the shock absorber 10
Since the traveling stroke speed Vi is in a deceleration state,
In such a case, the process proceeds to S218, and in this routine
The number of control steps temporarily set and the previous route
Is compared with the number of control steps step old set by the control unit.
In step S218, the control step number step becomes the control step number step.
 If smaller than old (“Yes” in S218), S21
Proceed to step 2 to set the control step temporarily set in this routine.
The number of steps is set as the number of control steps.
Thereafter, the process proceeds to S214, in which the setting made in the current routine is performed.
The value of the control step number step is stored as step old.
On the other hand, if “No” is determined in S218,
The number of control steps temporarily set in this routine
step is the number of control steps set in the previous routine
 If it is older than or equal to old, the process proceeds to S216, and the temporarily set system
Set the value of the number of steps, step, to a value less than the current value.
The number of control steps is replaced by step old.
Execute S214. Steps S208 to S218 are executed as described above.
By doing so, when the shock absorber 10 is in the extension stroke,
When the stroke speed Vi is in an accelerating state, the control
The number of steps increases, and the acceleration tendency of the stroke speed Vi
Is suppressed, and the stroke speed Vi is in a decelerating state.
If the number of control steps decreases, the stroke speed
The deceleration tendency of Vi is suppressed. Therefore, the stroke speed
The fluctuation of the degree Vi is suppressed and the sprung member
Since the amplitude of the vertical movement of the vehicle body 200 is also suppressed,
Both comfort and steering stability can be improved. On the other hand, it was judged "No" in S206.
If it is determined, the process proceeds to S220, where the determination flag Fc is
−1, that is, the shock absorber 10 has contracted.
It is determined whether it is a process. Determined as "Yes" in S220
If so, the process proceeds to S222, and the vehicle calculated in S204
It is determined whether the acceleration dVi / dt of the wheel L is 0 or less.
You. In the case where "Yes" is determined in S222,
Is a strike toward the shrinking direction of the shock absorber 10.
In such a case, the roking speed Vi is in an accelerating state.
First, the process proceeds to S224, and the temporary setting is performed in this routine.
Number of control steps set in the previous routine.
Compare with the specified number of control steps step old. S22
In 4, the control step number step is the control step number step old
If it is larger (“Yes” in S224), the process proceeds to S226.
The number of control steps temporarily set in this routine
Step is set as the number of control steps step. this
Then, the process proceeds to S228, in which the control set in this routine is performed.
The value of the number of steps step is stored as step old. one
On the other hand, when it is determined “No” in S222,
Number of control steps temporarily set in this routine step
Is the number of control steps set in the previous routine step old
In the following cases, the process proceeds to S230, where the temporarily set control mode is set.
The previous control in which the value of step number step becomes a value equal to or greater than the current value
The number of steps is replaced by step old.
Execute 28. On the other hand, if the result of determination in S222 is "No",
In this case, the shock absorber 10 moves toward the contraction direction.
Since the stroke speed Vi is in a deceleration state,
In this case, the process proceeds to S232, and the temporary setting is performed in this routine.
Number of control steps set in the previous routine.
Compare with the specified number of control steps step old. S23
In 2, the control step number step is the control step number step old
If it is smaller (“Yes” in S232), the process proceeds to S226.
The number of control steps temporarily set in this routine
Step is set as the number of control steps step. this
Then, the process proceeds to S228, in which the control set in this routine is performed.
The value of the number of steps step is stored as step old. one
On the other hand, when it is determined “No” in S232,
Number of control steps temporarily set in this routine step
Is the number of control steps set in the previous routine step old
In the above case, the process proceeds to S230, where the temporarily set control mode is set.
The previous control in which the value of the step number step becomes a value less than the current value
The number of steps is replaced by step old.
Execute 28. Steps S222 to S232 are executed as described above.
By doing so, when the shock absorber 10 is in the contraction stroke,
When the stroke speed Vi is in an accelerating state, the control
The number of steps increases, and the acceleration tendency of the stroke speed Vi
Is suppressed, and the stroke speed Vi is in a decelerating state.
If the number of control steps decreases, the stroke speed
The deceleration tendency of Vi is suppressed. Therefore, the stroke speed
The fluctuation of the degree Vi is suppressed and the sprung member
Since the amplitude of the vertical movement of the vehicle body 200 is also suppressed,
Both comfort and steering stability can be improved. Note that if the result of determination in S220 is "No",
In other words, if Fc = 0, the process proceeds to S234,
The number of control steps temporarily set to the number of control steps
Set this as a step, proceed to S236,
The value of the number of control steps set by
To remember. Thus, the shock absorber 10
By executing the damping force change control, the graph shown in FIG.
In addition, in both the extension and contraction strokes, the stroke speed Vi is
Shock absorbers are used in the area indicated by accelerating hatching.
10, the damping force is increased, and the stroke speed Vi is reduced.
The number of control steps is reduced in the area indicated by
become. FIG. 7 shows the embodiment described above.
In the flowchart, in S112 or S116
Example of 1 step as the number of steps to increase or decrease
Although shown, the present invention is not limited to this example.
Pre-determined multiple steps in
The number may be increased or decreased, and the number of steps to increase or decrease
Is set according to the magnitude of the stroke speed Vi.
Is also possible. [0081] As described above,Of the present inventionFor vehicles
According to the damping force control device, the relative displacement direction and the relative displacement speed
Control the damping force of the hydraulic pressure buffer based on the change state
By providing control means, the expansion and contraction of the hydraulic buffer
Optimal control can be performed for each stroke
Becomes Also,Of the present inventionIn vehicle damping force control device
Isfurther,Acceleration of relative displacement speed by control means
Increase the damping force when the vehicle is decelerating, and decrease it when the vehicle is decelerating.
Since control is performed to reduce the damping force,
The fluctuation of the relative displacement speed between the material and the unsprung member is suppressed,
Sudden changes in vehicle height are suppressed, thereby improving the riding comfort of the vehicle.
And steering stability can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view schematically showing a vehicle equipped with a damping force control device according to a first embodiment. FIG. 2 is a block diagram showing an input / output target in damping force change control and an ECU that performs control calculation. FIG. 3 is a longitudinal sectional view of a shock absorber used in each embodiment. FIG. 4 is an enlarged sectional view showing a main part of the shock absorber. FIG. 5 is a graph showing a relationship between a displacement speed V of a piston rod and a generated damping force F. FIG. 6 is a flowchart illustrating damping force change control. FIG. 7 is a flowchart showing S100 in FIG. 6; FIG. 8 is a graph showing an example of transition of a stroke speed, a vehicle height, and a speed derivative of a stroke speed. [Description of Signs] 2 ... Actuator, 10 ... Shock absorber, 20
0: body, 201: steering wheel, 203: steering angle sensor, 210: suspension arm, 220: stroke sensor, 230: electronic control unit.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masahiro Murata 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Satoshi Suzuki 1 Toyota Town Toyota City, Aichi Prefecture Toyota Motor Corporation ( 72) Inventor Yoshiyuki Hashimoto 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Co., Ltd. (56) References JP-A-6-147963 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B60G 1/00-25/00

Claims (1)

(57) Claims 1. A vibration generated between a sprung member and a unsprung member of a vehicle is attenuated by a predetermined damping force, and a relative force between the sprung member and the unsprung member is reduced. Speed less than 0.02m / s
Hydraulic buffer having a damping force variable function in a lower region, Displacement state detecting means arranged corresponding to the hydraulic buffer and detecting relative displacement between the sprung member and the unsprung member, Control means for controlling the damping force of the hydraulic pressure buffer means based on the relative displacement direction and the change state of the relative displacement speed obtained from the detection result of the displacement state detection means, the control means comprising: In the case of acceleration
When the damping force of the hydraulic buffer is increased and the vehicle is in a deceleration state
A damping force control device for a vehicle, wherein the damping force of the hydraulic pressure reducing means is reduced .