JP2000052735A - Control device for vehicle suspension mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To vary the damping force of a hydraulic shock absorber and/or the spring constant of an air spring according to a ride-on time. SOLUTION: This control device comprises a vertical acceleration sensor to detect sprung vertical acceleration of a vehicle, land at least one of a damping force variable type hydraulic shock absorber A and a spring constant variable type air spring B. When the sprung vertical acceleration detected by the vertical acceleration sensor exceeds a threshold G0, at least one of the damping force of the damping force variable type hydraulic shock absorber A and the spring constant of a spring constant variable type air spring B is switched to a high value state. When a continuous running time exceeds a prescribed value, by increasing the threshold G0, the damping force of the damping force variable type hydraulic shock absorber A and the spring constant of the spring constant variable type air spring B are hardly switched to a high value state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension mechanism applied to an automobile, a train or the like, which is used for riding, and more particularly to a damping force of a variable damping force type hydraulic shock absorber in consideration of the occupant's familiarity with vibration. Alternatively, the present invention relates to a control device for a vehicle suspension mechanism that switches a spring constant of a spring constant variable spring.

[0002]

2. Description of the Related Art In a vehicle suspension mechanism disclosed in Japanese Patent Application Laid-Open No. 7-266825, when the vertical acceleration exceeds a predetermined value, the damping force of a hydraulic shock absorber and the spring constant of an air spring are increased.
However, when the occupants get on the vehicle for a long time, they get used to the vibration,
Vibration (frequency) that makes you feel uncomfortable depending on the vibration of the vehicle
Also change. That is, the occupant feels discomfort mainly in the "fluffy feeling" of low-frequency vibration (about 2 Hz or less) in the early stage of boarding.
This low frequency vibration is also a vibration that easily induces motion sickness. However, as the ride time increases, you get used to low-frequency vibration,
The user feels uncomfortable due to the “stiffness” of high-frequency vibration (about 10 Hz or more).

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle in which the damping force of a hydraulic shock absorber and / or the spring constant of a spring constant variable spring is changed according to the riding time in view of the above-mentioned problems. A control device for a suspension mechanism is provided.

[0004]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a vehicle behavior detecting sensor for detecting the behavior of a vehicle, a variable damping force type hydraulic shock absorber and a variable spring constant type spring. A control device for a vehicle suspension mechanism that adjusts at least one of a damping force and a spring constant when a behavior of the vehicle detected by the vehicle behavior detection sensor exceeds a threshold value. When the continuous running time exceeds a predetermined value, the threshold value is changed so that the damping force and the spring constant are hardly increased.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally, low-frequency vibrations are suppressed by:
The damping force of a variable damping force type hydraulic shock absorber (hereinafter, simply referred to as a hydraulic shock absorber) of a suspension mechanism and the damping force of a spring constant variable type spring (hereinafter, simply referred to as a spring) and the spring constant variable type spring It is effective to increase the spring constant, and to suppress high-frequency vibration, it is effective to reduce the damping force of the hydraulic shock absorber of the suspension mechanism and the spring constant of the spring.

According to the present invention, the damping characteristics of the suspension mechanism are controlled in accordance with the occupant's familiarity with the vehicle vibration. When the continuous running time without opening / closing of the entrance door exceeds a predetermined value (for example, 30 minutes),
A set value of a relational expression for switching a damping force of a hydraulic shock absorber of a suspension mechanism or a spring constant of a spring with respect to a behavior of the vehicle such as a vertical vibration of the vehicle is changed. Specifically, the condition when the damping force of the hydraulic shock absorber of the suspension mechanism or the spring constant of the spring should be switched, that is, the threshold value (sensitivity) for the behavior of the vehicle such as vertical vibration is reduced, and the damping force or the spring constant is increased. Make it difficult to switch to the state.

If the suspension mechanism is controlled based only on the continuous running time, it may be inconvenient depending on the road condition. In other words, when the continuous running time exceeds a predetermined value (for example, 30 minutes), it is difficult to switch the damping force of the hydraulic shock absorber and the spring constant of the spring to a large state. I will. Therefore, whether the vehicle is in a high-speed running state is determined based on whether or not the vehicle speed is higher than a predetermined value (for example, 70 km / h).
km / h) for more than a predetermined period of time, it is determined that the road surface is stable enough to allow high-speed driving, and the damping force of the hydraulic shock absorber or the spring It is difficult to switch the spring constant to a large state.

[0008]

FIG. 1 is a side view showing a schematic configuration of an air spring type suspension mechanism for each wheel according to a first embodiment of the present invention. An eyeball 14 a formed by winding the front end of a beam 14 composed of two upper and lower leaf springs into a cylindrical shape is inserted between the bifurcated support plates 7 fixed to the vehicle frame 2, and connected by pins 8. The rear half of the lower leaf spring of the beam 14 is bent downward, and the rear end 14 b is supported by the vehicle frame 2 by the air spring B and the hydraulic shock absorber A.

The air springs B are connected to each other with the cup-shaped piston 19 on the lower side and the bellows 18 on the upper side, and the lower end of the piston 19 is fixed to the rear end 14b of the beam 14 by bolts with the extension plate 45 interposed therebetween. While bellows 18
Is fixed to the vehicle frame 2. An air pressure sensor for detecting the air pressure of the air spring B, specifically, a pressure switch 46 for closing the circuit when the air pressure is lower than a predetermined value, is provided inside the upper end of the bellows 18. The hydraulic shock absorber A has a lower end supported by the extension plate 45 of the beam 14 and an upper end supported by the support plate 20 of the vehicle frame 2. The hydraulic shock absorber A has a damping force adjuster 36 supported at a portion extending upward from the support plate 20.

The beam 14 is connected to the center of the axle 13 by a pair of U-bolts 41 at the front and rear. That is, while the pad 42 is superimposed on the upper side of the beam 14, the pad plate 4 sandwiching the upper and lower surfaces of the axle 13 is disposed on the lower side of the beam 14.
3 and 44 are applied, and the U-bolt 41
Are supported through, and the nut 41a is screwed and fastened.

The air chamber 17 of the air spring B is connected to the main air tank 3 via a known height adjustment valve 4. In order to increase or decrease the spring constant of the air spring B, the auxiliary air tank 5 is connected to the air chamber 17 via the solenoid valve 6. When the solenoid on-off valve 6 is opened, the spring constant becomes small (soft), and conversely, when the solenoid on-off valve 6 is closed, the spring constant becomes large (hard). Further, if two or more auxiliary air tanks 5 and two electromagnetic on-off valves 6 are provided on each wheel, and one or two of the electromagnetic on-off valves 6 are opened, the spring constant can be switched in three stages.

As shown in FIG. 2, the hydraulic shock absorber A has a cylinder 60 in which a piston 60 is inserted and an oil chamber 58 is formed above the piston 60, and an oil chamber 59 is formed below the piston 60.
The oil chamber 74 of the accumulator 70 is connected to one of the pressure valves 8 and 59 via a known bidirectional check valve 71 (may be omitted). The pressure accumulator 70 is partitioned into an oil chamber 74 and a compressed air chamber 75 by a diaphragm 73 inside the container 72. A hollow rod 53 integral with the piston 60 protrudes upward from the upper end wall 56a via a seal member 55. The outer end of the rod 53 is connected to the support plate 20 or the vehicle frame 2 via rubber bushes 49, 50, while the lower end wall 56b of the cylinder 56 is connected to the beam 14.

The principle configuration of the control valve C for adjusting the damping force of the hydraulic shock absorber A is as follows: a valve chamber 67 formed inside a piston 60; and a valve body rotatably fitted to the valve chamber 67. 66
The control rod 52 is connected to the rod 53 from the valve body 66.
And a damping force adjuster 36 composed of an electric motor is connected to the upper end of the control rod 52. An annular groove is formed in the inner peripheral surface of the intermediate portion of the valve chamber 67 and communicates with the oil chamber 58 via the passage 61. Also, arc-shaped grooves 63 a and 69 a formed on the inner peripheral surfaces of the upper and lower ends of the valve chamber 67 are communicated with the oil chamber 59 through the passage 68. A passage 62 extending radially outward from an intermediate portion of the axial passage 76 of the valve body 66 always communicates with the passage 61 via the annular groove, while a check valve 64,
A plurality of passages 6 extending radially outward from upper and lower ends than the upper and lower ends 65
Some of the members 3 and 69 can be selectively communicated with the grooves 63a and 69a, respectively.

When the hydraulic shock absorber A is extended, the oil in the oil chamber 58 flows through the passages 61 and 62, the check valve 65, and the passages 69 and 68 to the oil chamber 59, and when the hydraulic shock absorber A is contracted, the oil in the oil chamber 59 is discharged. Through the passages 68 and 63, the check valve 64 and the passages 62 and 61
Flow to 8. The valve body 66 is rotated by the damping force adjuster 36, and the grooves 63a, 6 of the passages 63, 69 extending from the passage 76.
As the number of communication with the passage 9a increases, the damping force decreases (softens), and the passages 63, 69 extending from the passage 76.
When the number communicating with the grooves 63a and 69a becomes smaller, the damping force becomes larger (harder).

FIG. 3 is a diagram for explaining the operation of the embodiment, and FIG. 4 is a block diagram of a control device of the vehicle suspension mechanism of the embodiment.
At least one of the damping force of the hydraulic shock absorber A and the spring constant of the spring B is obtained by the electronic control unit 26 from the signal of the vertical acceleration sensor 24 for detecting the vertical acceleration on the spring. The damping force adjuster 36 or the electromagnetic opening / closing valve 6 is driven to control the damping force or the spring constant to an optimum value, and the traveling time and traveling conditions (vehicle speed) are controlled.
The condition for switching the damping force of the hydraulic shock absorber A or the spring constant of the spring B is changed in accordance with.

FIGS. 5 to 8 are flow charts of a control program for performing the above-described control by the electronic control unit 26 comprising a microcomputer in the first embodiment. Figures 5-8
In p11-p20, p31-p41, p51-p62, p71
.About.p82 and p91.about.p98 represent each step of the control program. This program is repeatedly executed at predetermined time intervals. The control program is started at p11 in FIG. 5, and it is determined at p12 whether the door switch 21 is closed by the door switch 21 or not.
If the door is not closed, the process returns to p12. If the door is closed, the timer 23 measures the elapsed time from when the door is closed at p13, and a predetermined time (for example, 30)
Minutes) is determined. If a predetermined time has elapsed since the entrance door was closed, the threshold value (set value) G0 of the vertical acceleration on the sprung is set to G2 at p14, and if the predetermined time has not elapsed since the entrance door was closed, the spring is released at p15. Is defined as G1 (G1 <G2).

The vertical acceleration G on the spring is detected by the vertical acceleration sensor 24 at p16, and the vertical acceleration G on the spring is detected at p17.
Is larger than the threshold value G0. If the vertical acceleration G on the spring is smaller than the threshold value G0, the damping force of the hydraulic shock absorber A and the spring constant of the air spring B are switched softly at p19. If the vertical acceleration G on the spring is greater than the threshold value G0, the damping force of the hydraulic shock absorber A and the spring constant of the air spring B are switched to hardware at p19, and the control program is terminated at p20.

In the embodiment shown in FIG. 6, in order to determine whether or not the vehicle has started, the vehicle speed is detected by a vehicle speed sensor 22 instead of the door switch 21.
That is, the control program is started at p31, the vehicle speed V is detected by the vehicle speed sensor 22 at p32, and it is determined at p33 whether the vehicle speed V is higher than a predetermined value V0 (for example, a value of 5 km / h or less). . If the vehicle speed V is lower than the predetermined value V0, p32
When the vehicle speed V is higher than the predetermined value V0, it is determined whether or not a predetermined time has elapsed since the vehicle speed V became higher than the predetermined value V0 (after departure) at p34. ~ P41
Then, a control program similar to p14 to p20 in FIG. 6 is executed.

In the embodiment shown in FIG. 7, the control program is started at p51, and it is determined at p52 whether the door switch 21 is closed by the door switch 21 or not. If the door is not closed, return to p52. If the door is closed, p53.
It is determined whether or not a predetermined time has passed since the door was closed. If the predetermined time has not elapsed since the entrance door was closed, the process proceeds to p56, and if the predetermined time has elapsed since the entrance door was closed, the vehicle speed V is detected by the vehicle speed sensor 22 at p54, and the vehicle speed V becomes the predetermined value at p55. It is determined whether it is greater than V1 (for example, 70 km / h). If the vehicle speed V is lower than the predetermined value V1, the threshold value G0 of the sprung vertical acceleration is set to G1 at p56.
If the vehicle speed V is higher than a predetermined value V1 (for example, 70 km / h), the threshold value G0 of the vertical acceleration on the spring is set to G by p57.
2 (G1 <G2).

The vertical acceleration G on the spring is detected by the vertical acceleration sensor 24 at p58, and the vertical acceleration G on the spring is detected at p59.
Is larger than the threshold value G0. If the vertical acceleration G on the spring is smaller than the threshold value G0, the damping force of the hydraulic shock absorber A and the spring constant of the air spring B are switched softly at p60. If the vertical acceleration G on the spring is larger than the threshold value G0, the damping force of the hydraulic shock absorber A and the spring constant of the air spring B are switched to hardware at p61, and the control program ends at p62.

In the embodiment shown in FIG. 8, in order to determine whether or not the vehicle has started, the vehicle speed is detected by a vehicle speed sensor 22 instead of the door switch 21.
That is, the control program is started at p71, the vehicle speed V is detected by the vehicle speed sensor at p72, and the vehicle speed V is set to the predetermined value V0 at p73.
It is determined whether the value is greater than or not. When the vehicle speed V is lower than the predetermined value V0, the process returns to p72. When the vehicle speed V is higher than the predetermined value V0, the vehicle speed V becomes higher than the predetermined value V0 at p74 (after departure). It is determined whether a predetermined time has elapsed. If the predetermined time has not elapsed since the vehicle speed V became higher than the predetermined value V0, the process proceeds to p76.

If the predetermined time has elapsed since the vehicle speed V became higher than the predetermined value V0, the vehicle speed V is increased to the predetermined value V at p75.
It is determined whether it is greater than 1 (for example, 70 km / h). If the vehicle speed V is smaller than the predetermined value V1, the threshold value G0 of the vertical acceleration on the sprung is set to G1 at p76, and the vehicle speed V becomes equal to the predetermined value V1.
If it is greater than (for example, 70 km / h), the threshold G0 of the vertical acceleration on the spring is set to G2 (G1 <G2) at p77. Hereinafter, in p78 to p82, the same control program as in p58 to p62 in FIG. 7 is executed.

In each of the above embodiments, the damping force of the hydraulic shock absorber A and the spring constant of the air spring B are adjusted according to the running time and the running conditions (vehicle speed). The ride comfort of the occupant can be improved in accordance with the running time or the riding time only by increasing or decreasing one of the air spring B and the spring constant. Further, instead of the air spring, a metal spring with a variable spring constant can be used.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and is applicable to various control devices for controlling the rigidity of the suspension device according to the vehicle behavior. You. For example, a configuration in which each of the bounce, pitch, and roll modes of the vehicle is detected by a plurality of acceleration sensors as vehicle behavior detection means, and the system is applied to control for changing the rigidity of the suspension device, and a stroke sensor is used as the vehicle behavior detection means The present invention does not depart from the gist of the present invention, such as a configuration applied to control for changing the stiffness of the suspension device according to the stroke of the suspension device, a configuration applied to a so-called active suspension capable of continuously adjusting the stiffness of the suspension device. Of course, it can be implemented in various ways within the scope.

[0025]

As described above, the present invention comprises a vehicle behavior detection sensor for detecting the behavior of a vehicle, and at least one of a variable damping force type hydraulic shock absorber and a variable spring constant type spring. A vehicle suspension for switching at least one of the damping force of the variable damping force type hydraulic shock absorber and the spring constant of the variable spring constant type spring to a large state when the vehicle behavior value detected by the behavior detection sensor exceeds a threshold value; In the control device of the mechanism, by increasing the threshold value when the continuous running time exceeds a predetermined value, the damping force of the variable damping type hydraulic shock absorber and the spring constant of the variable spring constant spring are switched to a large state. This makes it difficult to change, and enables control of the suspension mechanism optimal for ride comfort in consideration of the occupant's familiarity with vehicle vibration.

[Brief description of the drawings]

FIG. 1 is a side view showing a schematic configuration of a vehicle suspension mechanism according to the present invention.

FIG. 2 is a side sectional view showing a schematic configuration of a variable damping force type hydraulic shock absorber employed in the vehicle suspension mechanism.

FIG. 3 is an operation explanatory view of the vehicle suspension mechanism.

FIG. 4 is a block diagram showing an outline of a control device for a vehicle suspension mechanism according to the present invention.

FIG. 5 is a flowchart of a program for controlling a damping force of a hydraulic shock absorber and a spring constant of an air spring by an electronic control device including a microcomputer.

FIG. 6 is a flowchart of a program for controlling a damping force of a hydraulic shock absorber and a spring constant of an air spring by an electronic control device including a microcomputer.

FIG. 7 is a flowchart of a program for controlling a damping force of a hydraulic shock absorber and a spring constant of an air spring by an electronic control device including a micro computer.

FIG. 8 is a flowchart of a program for controlling a damping force of a hydraulic shock absorber and a spring constant of an air spring by an electronic control device including a microcomputer.

[Description of Signs] A: Hydraulic shock absorber B: Air spring C: Control valve 2: Car frame 3: Main air tank 4: Vehicle height adjustment valve 5: Sub air tank 6:
Solenoid on-off valve 13: Axle 14: Beam 17: Air chamber 18: Bellows 19: Piston 21: Door switch 22: Vehicle speed sensor 23: Timer 24: Vertical acceleration sensor 26: Electronic control device 36: Damping force controller 41: U bolt 46 : Pressure switch (pneumatic pressure sensor) 52: control rod 53: rod 56: cylinder 58: oil chamber 59: oil chamber 60: piston 66:
Valve 67: Valve room 70: Accumulator

Claims (5)

[Claims] 1. A vehicle behavior detection sensor for detecting the behavior of a vehicle, and at least one of a variable damping force type hydraulic shock absorber and a variable spring constant type spring. When the behavior exceeds a threshold, the control device of the vehicle suspension mechanism adjusts at least one of a damping force and a constant of a spring. When the continuous running time exceeds a predetermined value, the threshold is changed, and the damping force is changed. A control device for a vehicle suspension mechanism, wherein a force and a spring constant are hardly increased. 2. The vehicle behavior detecting sensor according to claim 1, wherein the vertical acceleration on the spring is detected by an acceleration sensor. When the vertical acceleration on the spring exceeds a threshold value, at least one of a damping force and a spring constant. 2. The control method according to claim 1, wherein the control is performed such that one is increased, and when the continuous running time exceeds a predetermined value, the value of the vertical acceleration on the spring, which is the threshold value, is changed to be increased. Control device for vehicle suspension system. 3. The continuous running time is obtained by measuring an elapsed time since a door of a vehicle is closed.
Or the control device of the vehicle suspension device according to 2. 4. The control device for a vehicle suspension system according to claim 1, wherein said continuous running time is obtained by measuring an elapsed time of a vehicle speed equal to or more than a predetermined value. 5. The control device for a vehicle suspension according to claim 3, wherein the change of the threshold value is prohibited when the current vehicle speed does not exceed a predetermined value.