JPS6175007A - Vehicle suspension device - Google Patents

Abstract

PURPOSE:To enhance the running characteristic of a vehicle, by controlling a damper in such a way that the damping force on one side which receives acting force subjecting a vehicle body to variations is made greater than that on the other side which recovers the vehicle body. CONSTITUTION:Data concerning the running of a vehicle is delivered from various sensors to a control circuit which operates each actuator 17. For example, upon anti-dive operation the actuator 17 rotates a movable plate 15 in each front side hydraulic damper U, and a third communication passage 11 is confronted with an orifice a1 while a fourth communication passage 12 is confronted with an orifice a2. Meanwhile, in a rear side damper U the third communication passage 22 is confronted with an orifice C1 while the fourth communication passage 12 is confronted with an orifice C2. Accordingly, on the front side the damper becomes hard upon retraction of a piston rod 6 while it becomes soft upon extension of the same. Meanwhile on the rear side the damper acts reverse to the above.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to improvements in suspension systems.

(Prior Art) It is widely known that a suspension system is located between an axle and a vehicle body, and connects the two to absorb shock from the road surface and improve ride comfort. It is generally composed of a coil spring and a hydraulic shock absorber that moderately suppresses the vibration by damping force generated as the piston rod expands and contracts.

By the way, in recent suspension systems, as part of improving riding comfort, anti-dive (preventing the vehicle body from leaning forward during braking), anti-a-roll (preventing misappropriation during turning), There is a tendency for vehicles to have the function of squatting (preventing the vehicle from rolling downwards due to acceleration). As for the configuration that provides each of these functions, when driving off the coast where any of the phenomena of nose dive, CII jetting, and squatting occur, each hydraulic shock absorber in the suspension system of each wheel (four axles and all wheels) is The damping force when the piston/rod expands and contracts is switched so that both are extremely large. With this configuration, each hydraulic shock absorber has a large damping force that acts as a resistance against the phenomena of nose dive, rolling, and squat, and attempts to prevent the occurrence of these phenomena as much as possible.

(Problems to be Solved by the Invention) However, the phenomena of nose dive, a-ring, and squat occur when the vehicle is in a running state, and in that running state, the phenomena are unpredictable depending on the road surface condition, road conditions, etc. Simply increasing the damping force when the piston/rod expands and contracts in order to prevent nose dive, A-ring, and squat phenomena is not enough to deal with unexpected situations. Not only will this not be possible, but once these phenomena occur on the vehicle body, the ability to restore the vehicle body will be hindered. To explain such a specific example regarding the A-ring in detail, when turning to the right while moving forward, in order to prevent the vehicle from collapsing, it is necessary to The blowing damping force when the piston/rod is shortened must be large.However, in the above configuration, the damping force when the piston/rod is shortened is also large in each hydraulic shock absorber on the right side in the forward direction. If the right wheel happens to run onto a convex part of the road surface in the forward direction, the vehicle body will be thrown up due to the synergistic effect of the centrifugal force exerted on the outside g11.

In addition, in each hydraulic shock absorber on the left side in the forward direction, once the piston rod is shortened, regardless of the damping force that occurs when the piston/rod is shortened due to a sudden right turn, etc., once the piston rod is shortened, the Since the damping force is also large, it becomes difficult for the piston/rod to extend, which hinders the ability of the vehicle body to restore its tilt when the degree of turning becomes gradual.

The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to improve the running performance of a vehicle.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a method of causing the body of the shock absorber to move when the vehicle is running in a state that causes rolling, nose dive, or squat. The structure is such that the damping force (11) against the acting force is controlled to be larger than the damping force (11) against the acting force that moves the vehicle body forward.

(Function) With the above-described configuration, the hydraulic shock absorber U of the suspension system for each wheel can be used for nose dive, rolling, and squat.
! 1. 10,000 measures to prevent each phenomenon as much as possible depending on the situation.
To quickly restore a vehicle body even if each IU phenomenon occurs once.

(Effects of the Invention) Therefore, in the present invention, it is possible to prevent nose dive, -1 ring, and squat valley phenomena as much as possible.
By quickly restoring the vehicle body, driving performance can be dramatically improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

In Figures 1 to 4 (2), 1 is a cylinder of a hydraulic shock absorber U, and a free piston 2 is movable in the cylinder 1. It is divided into two parts: a gas chamber 3 and an oil chamber 4.

The gas chamber 3V is filled with high pressure gas, and the oil chamber 4V is filled with oil.

A piston 5 is slidably inserted into the oil chamber 4, and the oil chamber 4 is defined by the piston 5 into a lower chamber 1 and an upper chamber R2. A piston rod 6 is connected to the piston 5, and the piston/rod 6 extends out of the cylinder 1 through the upper chamber 2.

The piston 5 has a first pipe that communicates the lower chamber R1 and the upper chamber 2.
A communication path 7 and a second communication path 8 are provided. The upper part of the piston 5 is provided with a first communication passage 7 when the pressure in the lower chamber Rt increases and the pressure difference between the lower chamber 1 and the upper chamber 2 reaches a certain value when the piston/rod 6 is shortened. Open normally closed first
A damping valve 9 is attached to the lower part of the piston 5, and when the piston rod 6 is extended, the pressure in the upper chamber increases and there is a pressure difference between the lower chamber 1 and the upper chamber 2. A normally closed second damping valve 10 opening each second passage 8 is installed.

The piston 5Vc is formed with third and fourth communication passages 11.12 that face each other with the narrow center of the piston/rod 6 in between, and the third and fourth communication passages 11.12 are respectively connected to the upper chamber 2. It communicates with the lower room No. 1.

Each of the third and fourth communication passages 11 and 12 is provided with a check valve 14, and the check valve 13 allows only the flow of oil from the lower chamber 1 to the upper chamber 1LL2. 14 only allows oil to flow from the upper chamber 2 to the lower chamber Rx. A disk-shaped movable plate 15 is held inside the piston 5 so as to be rotatable around the axis of the piston/rod 6, and the plate surface of the movable plate 150 is connected to the third and fourth communication passages 11.
．． 12 t-crossing. This movable plate 15 has a plurality of orifices al*a2eb1mb in its axial direction.
2*C1s'2 are drilled in each orifice a1.
a2*blsbItC1, C2 can face the third and fourth communicating paths 11 and 12 by rotating the movable plate 15 about its axis. Each orifice a1m&@, bl +b2m'1eC2 is a pair of orifices that face each other with the axis of the movable plate 15 in between. , and when the -10,000 orifice faces the third communication path 11, the other orifice faces the fourth communication path 12. Each orifice alsa2+b1 tb2
s'l *The opening area of C2 is the orifice a1 and C2)
Orifices b1 and b2) Orifices cl and C2 are equal to each other, and the orifices al, b1, and C1 become smaller.

The movable plate 15 has its axis Vci? operating rod 16
The operating rod 16 rotatably passes through the piston/rod 6 in its axial direction.

An actuator 17 is connected to the operating rod 16, and the actuator 17 allows the operating rod 16 to rotate as appropriate about its axis.

The hydraulic shock absorber U according to the present invention is used as a part of a suspension system for each wheel, and accordingly, the actuator 17 is used for each hydraulic shock absorber U. Each actuator 17a, 17b#17C#17d is connected to various sensors 19 to 26 and an off switch 27vC via a control circuit 18, as shown in FIG. 4, and the control circuit 1s)
In addition to this, a display lamp 28 is connected to C.

The control circuit 18 controls each actuator 17a according to output signals from various sensors 19 to 26 and an off switch 27.
~17d is activated, and the paired orifices ax and aa
, bx and b! 1. Connect C and C2 to third and fourth communication paths 1L
It has a function that allows you to see 12 times. This switching selection of each orifice will be described later.

Here, in the case where the hydraulic shock absorber U has the orifice b5 facing the third communication path 11 and the orifice b2 facing the fourth communication path 12, the hydraulic shock absorber U is shown as Bl and B2 in FIG. The characteristic curves Bz and B2 are normal and custom-made damping force. In addition, the hydraulic shock absorber U has the orifice a1 facing the third communication path 11 and the fourth communication path 1.
In the case of 7'C with orifice a2 facing 2, the characteristic curve A1 has a gentler rise than the characteristic curve B1, and the characteristic curve A2 has a steeper rise than the characteristic curve B2.
When the orifice C1 faces the fourth communication passage 11 and the orifice C2 faces the fourth communication passage 12, the characteristic curve B
A characteristic curve C1 with a steeper rise than L, and a characteristic curve B2
This shows a characteristic curve C2 with a gentler rise than the curve C2. When each damping force at this initial rise reaches a predetermined value or more, the first and second damping valves 9 and 10 open, and the hydraulic shock absorber U exhibits each predetermined damping force. This first and second
The opening points of the contraction valves 9 and 1o are points Pi where each characteristic curve bends.

Corresponds to B2.

The various sensors 19 to 26 include a vehicle speed sensor 19, a brake sensor 20, a shift position sensor 21, and a blinker sensor 22.
) Handle angle sensor 23, accelerator opening sensor 24, longitudinal acceleration sensor 25, lateral acceleration sensor 26,
and an off switch 27.

As the vehicle speed sensor 19, a sensor used for an energized speedometer, a speed control, etc. is used. A brake lamp switch is used as the brake sensor 20. In the soft position, the sensor 21 detects which stage of forward, temporary, and forward movement the 77 Treper is located.

As the turn signal sensor 22, a turn signal inch is used. As the steering wheel angle sensor 23, a dip/shimimeter that rotates together with the steering wheel shaft, an absolute type a-tally encoder, or an incremental type a-tary encoder with or without a zero position is used. As the accelerator opening height 24, a switch whose contacts close when the accelerator is opened beyond a predetermined level is used. The longitudinal acceleration sensor 25 and the lateral acceleration sensor 26 utilize the inertia of a weight or the like to detect an acceleration of a predetermined amount or more and its direction using a switch contact or a phototransistor. Off switch 27! 'f This switch 27 is installed in the driver's seat, and is used when the driver wants to drive with the suspension characteristics during submersible driving.
By inputting, the normal damping force is changed by 1 level (2nd
In the figure, orifice bx, B2 is selected. ).

The display lamp 28 indicates the selection of switching of the eggplant characteristics (selection of each orifice at, a2.bt, b2.cx, and cz) and the occurrence of failures of various sensors 19 to 2G.

Next, basic controls, priority relationships of input information from each ship sensor, and basic 1δ processing will be explained.

1) Basic restrictions (&) Anti-dive When the brake pedal is depressed when the vehicle speed is above a predetermined value, the vehicle speed sensor 19 and the brake sensor 2o detect the state, and the longitudinal acceleration sensor 25 detects the state, and each detection signal is sent to the control circuit. 18
'lc people are fired. The control circuit 18 outputs a corresponding output signal to each actuator 17a to 17d based on both of the detection signals, and outputs a corresponding output signal to each actuator 17a to 17d.
t-actuate. That is, in each hydraulic shock absorber U on the front side, the movable plate 15.15 is rotated by the actuators 17a, 17b, and the third communication path 11
The orifice aX faces the fourth communication path 12, and the orifice a2 faces the fourth communication path 12. - In each hydraulic shock absorber U on the rear side, 15 orifices C1 facing the movable plate 1 face the third communication path 11, and orifices C2 face the fourth communication path 12.

Therefore, in each hydraulic shock absorber U on the front side, when the piston rod 6 is shortened, the damping force is larger than in the normal state (when orifices bx, bz are selected), and when the piston rod 6 is extended, the damping force is larger than the normal state (when orifices bx, bz are selected). smaller than the normal state. Therefore, its shortening motion becomes hard, and its extension motion becomes soft. In addition, in each hydraulic shock absorber U on the rear side, the piston rod 6
When extending, the damping force becomes larger than the normal state,
When the piston rod 6 is shortened, the damping force becomes smaller than in the normal state. Therefore, the extension motion is hard and the shortening motion is soft. This makes it possible to adequately deal with nose dives, and even if nose dives occur, the vehicle body quickly recovers.

In addition, when Mugishin is used, the anti-dive effect is opposite to the above.

Φ) Anti-roll At a predetermined vehicle speed or higher and at a predetermined angle or higher...When the steering wheel is turned to the left or right or either the left or right turn signal is turned on, this condition is detected by the vehicle speed sensor 19, steering wheel angle sensor 23, and left/right acceleration sensor. 26, the turn signal, and the sensor 22 detect, and each detection signal is input to the control circuit 18. The control circuit 18 outputs corresponding output signals to each of the actuators 17a to 17d based on each of the detection signals, and operates each actuator 1'''-17° to 17d.
That is, when you turn the steering wheel to the right or turn on the power line indicating the right turn signal, 7 on the right side in the forward direction (27) In each hydraulic shock absorber tJ on the rear side, the third communicating path 11 is connected to the movable plate 1. The orifice C2 faces the fourth communication path 12.On the other hand, the orifice C2 faces the fourth communication path 12.On the left front rear side in the forward direction.In each hydraulic shock absorber, the orifice a1 of the movable plate 15. The fourth communicating path 12 has an orifice a facing the third communicating path 11.
2 is coming. For this reason, 7 on the right side when facing the forward direction.
In each hydraulic shock absorber U on the 0/tria side, the damping force is larger than in the normal state when the piston rod 6 is extended, and the VC+J damping force when the piston rod 6 is short is smaller than in the normal state. Therefore, the extension motion is hard and the shortening motion is soft. In addition, in each hydraulic shock absorber U on the front and rear side on the left side in the forward direction, the damping force becomes larger than the normal state when the piston rod 6 is shortened, and the damping force becomes larger than the normal state when the piston rod 6 is extended. will also become smaller.

Therefore, the shortening motion becomes hard and the extension motion becomes soft. (If you turn the steering wheel to the left or turn on the left turn indicator, the driver will be facing 70 meters on the right side in the forward direction.) In each hydraulic shock absorber U on the IJA side, the third and fourth communication passages 11
．． Predetermined orifices al, a2 face 12, and predetermined orifices C1, C2 face third and fourth communication passages 11, 12 in each hydraulic shock absorber on the front and rear side on the left side in the forward direction.

Therefore, in the former case, the shortening motion becomes hard and the extension motion becomes soft. In Mugiya, the shortening motion is soft and the extension motion is hard. As a result, it is possible to sufficiently deal with rolling, and even if rolling occurs, the recovery is quickly performed. In the case of anti-roll, the turning direction determination based on the steering wheel operation is given priority over the blinker operation.

(C) Anti-squat When the accelerator pedal is depressed by a predetermined amount or more at a predetermined vehicle speed or less, the vehicle speed sensor 19, shift position sensor 21,
Accelerator opening sensor 24, longitudinal acceleration sensor 25,
Each detection signal is input to the control circuit 18.

The control circuit 18 outputs an output signal to each actuator 17a to 17d based on the detection signal. this【
Therefore, in each front-side hydraulic shock absorber UVc, the orifice C1 of the movable plate 15.15 faces the third communication path 11, and the orifice C2 faces the fourth communication path 12. on the other hand,
In the rear hydraulic shock absorber, the orifice a1 of the movable plates 15, 15 faces the third communication path 11, and the orifice a
2 faces the fourth communication path 121C. Therefore, in each hydraulic sharp sea bream device U on the front side, the damping force is made larger than the normal state when the piston rod 6 is extended, and the damping force is smaller than the normal state when the piston rod 6 is shortened. Therefore, the extension motion is hard and the shortening motion is soft.

Further, in each rear hydraulic shock absorber U having a diameter of 1 μm1, the damping force becomes larger than the normal state when the piston rod 6 is shortened, and becomes smaller than the normal state when the piston rod 6 is extended. Therefore, its shortening motion becomes hard, and its extension motion becomes a knot. As a result, it is possible to sufficiently deal with squats, and even if a squat occurs, the vehicle body can quickly recover. still,
When moving in reverse, the anti-squat effect is the opposite of the above case.

In the anti-nose dive action, anti-roll action, and anti-squat action, when acceleration is detected from the acceleration sensor 25.26 K, the detection signal is given priority over the detection signals from other sensors. This is because the acceleration sensors 25 and 26 cannot detect the acceleration that has already occurred, especially when the vehicle body spins when braking or when turning the vehicle's trunk. This is because the direction of acceleration can be detected more accurately than other indirect means in cases such as when the driver turns the steering wheel in the opposite direction due to a flow of gas.

Nose dive and cyljing, or squat and a-
The rings overlap and the orifices ax, ag, bt
, ba, ct, and cz, if the switching selection directions (direction of rotation of the movable plate 15) are contradictory, one should be selected depending on the motion characteristics of the vehicle body depending on the individual vehicle model, or if the magnitude of acceleration can be detected. The priority can be determined by referring to that value. Of course, in the above case, the normal damping force characteristics may be left as is.

In addition, the control circuit 18 determines that conflicting driving conditions, such as nose dive and squat, occur simultaneously based on the brake signal and the accelerator opening signal, and outputs the output from the acceleration sensor 25, 26 to the control circuit. 1
When 8 is not input, orifice al and @2. bi and b2. The selection of C1 and C2 may be determined, or the normal damping force characteristics may be left as is (selection of orifices b1 and b2).

Various types? The output signals from 19 to 26 are processed as follows to prevent chattering of the sensor contacts or minute signal fluctuations and noise present in the sensor output signals from leading to meaningless minute movements of the actuator 17. administer.

For analog quantitative signals such as vehicle speed and steering wheel angle,
Hysteresis is added to the threshold value. Furthermore, in order to prevent loss of connectivity with respect to signals generated by the -switch contact, a delay time element is provided that acts only when the signal disappears. In addition, this delay time element can be used for signals that the analog signal exceeds the threshold instead of the hysteresis described above, or for signals that appear as a result of signal judgment, such as the result of a vehicle speed signal and a brake signal. It can also be used for the nose dive signal output from the control circuit 18.

The signal processing of the steering wheel angle sensor 23 during anti-roll is basically performed to determine whether or not the steering wheel has been turned by a predetermined angle or more, but due to coordination, the steering wheel can rotate at a predetermined rotational speed or higher even if the predetermined angle has not been reached. When this happens, an equivalent judgment is made.

When using an a-tary encoder without zero position output as a steering wheel angle sensor, the steering wheel angle position corresponding to straight driving is determined from the past steering wheel angle position, but this determination depends on the vehicle speed and the presence or absence of lateral acceleration. It is also corrected by confirming straightness.

Although one embodiment has been described above, the present invention also includes the following aspects.

■ The orifice switching selection may be done in two stages. For example, a combination of a normal damping force characteristic and a damping force characteristic that is thicker than the normal state when the piston rod 6 is shortened and smaller than the normal state when the piston rod 6 is extended.

■ The switching selection of Oriais may be set to 4 or more stages.

For example, if the normal damping force characteristic is divided into two stages, one is a slightly larger case and the other is a slightly smaller one when the piston rod is extended and shortened, and either one is set as the normal damping force characteristic and installed in the driver's seat. selected by the switch.

(2) The normal damping force characteristics may be divided into two stages, one for high speed and one for low speed, and the low speed orifice may be switched to the high speed orifice at a predetermined vehicle speed or higher. In this case, the damping force is made slightly larger when the piston rod 6 is extended for high speeds than for low speeds.

Brief explanation of the four factors FIG. 1 is a longitudinal cross-sectional view showing a hydraulic shock absorber according to the present invention, FIG. 2 is a plan view showing a movable plate, and FIG. 3 is a diagram showing a hydraulic shock absorber according to the present invention. Figure 4, a characteristic diagram showing damping force characteristics, is an electrical system diagram according to the present invention.

U...- Hydraulic shock absorber

Claims (4)

[Claims] (1) When the vehicle is running in a state that causes rolling, nose dive, or squat, the damping force on the side of the shock absorber that responds to the acting force that moves the heavy body is lower than the damping force that responds to the acting force that restores the vehicle body. A vehicle suspension system characterized in that the vehicle suspension system is controlled to increase the size of the vehicle. (2) In claim 1, when the vehicle is running in fluctuations, the acting force that increases the damping force against the acting force that causes the vehicle body to fluctuate, as compared to the damping force that occurs during steady running, and also causes the vehicle body to recover. A vehicle suspension system characterized by reducing the damping force on the opposite side. (3) A vehicle as set forth in claim 1, characterized in that when the vehicle is running in fluctuations, only the damping force on the side that is responsive to the force that causes the vehicle body to fluctuate is greater than the damping force that is in steady running. Suspension system. (4) A vehicle as set forth in claim 1, characterized in that when the vehicle is running in fluctuations, only the damping force on the side that deals with the acting force that restores the vehicle body is made smaller than the damping force during steady running. Suspension system.