JPH02102942A - Hydraulic damper controlling device - Google Patents

Abstract

PURPOSE:To control the spring constant and the damping characteristic at the same time by furnishing an adjusting means, which increases the generated damping force with displacement toward max. compression in a compression stroke and increases the same with displacement toward max. elongation in the elongation stroke. CONSTITUTION:Outputs from a car speed sensor 53 and a condition sensor 54 are read, and if it is in normal operating condition, the generated damping force is used as standard. In special operating condition, an incremental rate with respect to the displacement of damping force is selected by reference to the preset 1G value from a 1G input terminal on the basis of signals from a stroke sensor 51 and a speed sensor 52. In compression stroke, the degree of opening of a damper valve 58 (valve opening pressure) is so set as to generate a compression side damping force in accordance with the stroke position. When max. compression is attained, the damping force is changed over to the min. value set previously. In elongation stroke, on the other hand, the degree of opening of the damper valve 58 is so set as to produce an elongation side damping force in accordance with the stroke position. When max. elongation is reached, the damping force is switched to the min. value predetermined.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus for optimally controlling the suspension characteristics of a hydraulic shock absorber such as a front fork of a two-wheeled vehicle depending on operating conditions.

(Prior art) For example, by variably controlling the damping force characteristics of the front 7F and rear suspension according to driving conditions, ride comfort and steering stability are improved. Various proposals have been made, such as in Publication No.-171133.

This attempts to variably control the damping force generated by installing a solenoid valve in the passage through which hydraulic oil flows as the piston moves, and by changing the opening degree of this solenoid valve depending on the operating conditions. It is something.

By weakening the damping force when driving at low speeds, the expansion and contraction of the front 7 oaks is softened to improve ride comfort, and when driving at high speeds, the damping force is set to be strong.
This makes the expansion and contraction stiffer and improves maneuverability.

However, such hydraulic pressure H and the load of the impactor (!!J rack)
The characteristics are actually the combination of the damping force of the shock absorber and the characteristics of the suspension spring, such as an attached metal spring or air spring.

Of these, the damping force largely depends on the speed of the fluid passing through the damping valve, in other words, it is generated depending on the piston speed of the a* device, so for example, even when the opening degree of the solenoid valve is large or small, If the expansion/contraction speed is extremely slow, the generated damping force will hardly change.

Figure 5 shows the relationship between the stroke and the load when the hydraulic shock absorber expands and contracts extremely slowly.Since the resistance value due to the damping force hardly changes, the load change with respect to the stroke is due to the spring force. It depends only on the characteristics, and there is almost no difference in load between the compression side and the expansion side. The characteristic line indicated by the dashed line in the figure corresponds to the spring constant k of the suspension spring, and the higher the spring constant, the stronger the slope. In addition,
The upper side of this - point 5J\ line shows the load on the compression side including the damping force, and the lower side shows the load characteristics on the expansion side.

On the other hand, when a shock absorber is expanded and contracted at a certain speed, a damping force corresponding to the operating speed is generated, so the load characteristics of the shock absorber are the spring characteristics plus the damping force.
The result will be as shown in Figure 16.

This figure shows the characteristics when the operating speed is changed to V, V2rV3, respectively, and as the operating speed increases, the generated damping force increases, so the load difference between the compression side and the extension side with respect to the stroke F stroke position is expands. This model shows a damping valve whose characteristics are set so that the damping force generated on the expansion side is relatively larger than on the compression side, as is the case with standard hydraulic shock absorbers. There is.

In this way, the generated damping force changes depending on the operating speed,
Further, even at the same speed, the damping force can be changed by changing the opening degree of the damping valve, but the spring constant of a suspension spring such as a metal spring or an air spring in the load characteristics of the shock absorber does not change.

By the way, as shown in FIG. 7, the characteristics of the shock absorber that are required when emphasis is placed on the cushioning feel in the normal running speed range of the vehicle are that both the spring constant and the damping force are set to be low.

On the other hand, when driving at high speed, accelerating or decelerating, etc., when emphasis is placed on maneuverability, the preferred characteristics are to set both the spring constant and the damping force to a high value, as shown in FIG.

However, since it is not possible to satisfy both of these requirements with the normal type, we selected a moderate spring constant and damping force as shown in Figure 9, taking into consideration the balance between bump comfort and handling stability. are doing.

As mentioned above, the damping force can be changed depending on the operating conditions, but regarding the spring constant, the structure of varying the spring constant of metal springs and air springs is very complicated and requires a large drive Due to the power requirement, it was difficult to apply it to the front 7 oak or rear suspension system of motorcycles, and it was not practical.

Therefore, in the past, there was no way to approach the requirements even slightly by adjusting only the damping force, but the present invention solves this problem by controlling the flow of the working fluid, which substantially improves the damping characteristics as well as the suspension spring. An object of the present invention is to provide a control device for a hydraulic pressure HNn that can also variably control the spring constant of the hydraulic pressure HNn.

(Means for Solving the 7s Problem) The present invention provides means for detecting the displacement of a shock absorber, means for determining the compression side stroke and the rebound side stroke from the detected displacement, and the means for determining the compression side damping force and the rebound side damping force. means for adjusting each, and the adjusting means so as to increase the generated damping force as the displacement is in the maximum compression direction in the compression side stroke, and increase the generated damping force as the displacement in the maximum extension direction in the extension side stroke. and control means for driving.

Further, means for determining the operating state is provided, and the control means is operated according to the operating state.

(Function) What is the load characteristic of a shock absorber? In the standard state, the spring constant and damping characteristic are set with emphasis on riding comfort. For example, in driving conditions where it is necessary to improve handling stability, the damping force is set as a displacement. Control variably depending on the direction.

That is, in the compression stroke, the damping force increases as it moves toward the direction of maximum compression, and at the same time as the displacement switches from compression to the direction of extension, conversely, the damping force goes from a low state to the direction of maximum extension. Therefore, the damping force is increased.

As a result, the load characteristics of the shock absorber have a high apparent spring constant, and the damping characteristics also increase in accordance with the magnitude of the damping force, improving maneuverability.

(Example) The drawings illustrate embodiments of the invention.

In Fig. 1, 1 is a stroke sensor for detecting the expansion/contraction displacement of the 41 damper, 2 is a damper speed sensor that also detects the expansion/contraction speed, 3 is a vehicle speed sensor for detecting the speed of the vehicle, and 4 is a vehicle speed sensor for detecting the speed of the vehicle. This is a state sensor for detecting vehicle body conditions such as tilt angle, acceleration, deceleration, etc., and each of these detection signals is input to the control roller 5. Further, a signal is also input to the controller 5 from a sensor 6 for detecting the IG position (neutral position) of the shock absorber. The IG position refers to the stationary stroke position of the damper when the vehicle is stationary, and is roughly the center position of the amplitude.

As will be described later, the controller 5 generates an exciting current for the solenoid coil (driving means) 7 that adjusts the opening degree (valve opening pressure) of the damping valve (damping force adjusting means) 8 according to the displacement and direction of the shock absorber 41. and variably control the load characteristics of the shock absorber, that is, the composite load characteristics of the suspension spring characteristics and the damping characteristics.

FIG. 2 is a flowchart showing an example of the control operation of the control controller 5. As shown in FIG.

To explain this, we first read the outputs of the vehicle speed sensor 3 and condition sensor 4, and then check whether the vehicle is in normal driving mode with emphasis on end comfort.
It is determined whether the vehicle is in a special driving state that emphasizes handling stability (step S1.32). In the normal operating state, the generated damping force is maintained at the standard state in step S3.

On the other hand, during special driving conditions such as high speed driving, acceleration/deceleration, and cornering, the signals from the stroke sensor 1, speed sensor 2, and IG sensor 6 are read, and the signals are set in advance based on these signals. Select the rate of increase of the damping force with respect to the displacement (step S4.5).

At step S61, it is determined whether the compression stroke is in progress from the change in the output of the stroke sensor.

If it is a compression stroke, the pressure will be 11111 depending on the stroke position.
The opening degree (valve opening pressure) of the damping valve is set according to the stroke position so that damping force is generated (according to the selected increase rate). This operation is repeated until the maximum compression position is reached (step S7.8).

When the maximum compression position is reached, the damping force is switched to a preset minimum value in step S9.

On the other hand, if it is determined in step S6 that the compression stroke is not in progress, it is determined in step SIO whether or not the expansion stroke is in progress.

In the case of an extension stroke, similarly to the above, the opening degree of the reduction valve is set according to the stroke position so that the extension damping force increases according to the stroke position. This operation is repeated until the most extended position is reached (step Sll, 12). When the most extended position is reached, the damping force is switched to a predetermined minimum value in step S13.

After this, the process returns to step S6 and the same operation is repeated.

When it is determined in step SIO that it is not an extension process,
In other words, if it is not in the compression stroke in step S6 and is not in the extension stroke in step S10, the expansion and contraction movement has discontinued and the buffer has returned to the stationary state or is originally in the stationary state.C), Step S14 Set the damping force at the IG position and return to the initial state.

Next, a concrete example of the two buffers shown in FIG. 3 is shown. This example is 7
0n) What is the damping force of the fork? ! An inner tube 2 is slidably inserted into the inside of the hour tube 1, and a damper 3 is inserted inside these.
will be installed.

In the damper 3, a piston 5 attached to a piston rod 6 connected to an inner tube 2 is slidably housed in a sill 4, and this sill 4 is erected at the bottom of the outer tube 1.

Inside the damper 3, a lower oil chamber 7 that contracts when the damper is operated toward the compression side and an upper oil chamber 8 that contracts when the damper operates toward the extension side are defined via the piston 5. The piston 5 is provided with a check valve 5A that opens only during compression to allow hydraulic oil to flow from the lower oil chamber 7 to the upper oil chamber 8. An oil reservoir chamber 9 is formed above the damper 3 and located inside the inner tube 2, and this oil reservoir chamber 9 is connected to the annular passage 1 on the outside of the sill 4.
0 and communicates with the lower oil chamber 7 via a check valve (base valve), not shown, arranged at the bottom of the cylinder 4. This check valve is designed to allow hydraulic oil to pass from the oil reservoir chamber 9 to the lower oil chamber 7 without resistance during the extension operation.

A valve case 13 is attached to the upper end of the inner tube 2, and a valve case 13 is installed coaxially with this solenoid 11.
A damping valve 12 for both expansion and compression is provided, and the piston rod 6 passes through the center thereof. A passage 25 formed through the center of the piston mouth/throat 6 opens one end to the upper oil chamber 8 and the other end to the upstream side of the damping valve 12.

The distance between the lower surface of the valve case 13 and the upper surface of the damper 3 (
A suspension spring 14 is arranged via moss, spring sea) 14A, 14[3.

The valve case 13 also serves as a cap, and is formed in a cylindrical shape and is hinged to the inner circumference of the inner tube 2 via a screw g15, in which the solenoid 11 and damping valve 12 are housed. A bobbin 17 made of a non-magnetic material is attached to a piston rod 6 passing through the center of the solenoid 11, and a coil 16 is wound around the bobbin 17. The hollow piston rod 6
A core 18 of magnetic material is inserted inside the coil 1G and closes the end of the passage 25.

In the yoke valve 12, a disk-shaped valve 21 made of a magnetic material is arranged so as to be able to move toward and away from a valve seat 20 having a boat 22 fixed to the outer periphery of the piston rod 6. The inner periphery of the valve seat 20 is made of a magnetic material, and the valve seat 20 is made of a magnetic material.
The outer periphery of the boat 22, which is blocked by the boat 22, is made of a separate non-magnetic material. Further, the valve case 13 into which the outer circumference of the valve seat (valve seat) 20 fits is formed of a magnetic material, and when the solenoid 11 is energized, it passes from the piston rod 6 made of magnetic material to the inner circumference of the valve seat, the valve 21, and the valve case 13. By configuring a closed circuit magnetic path, the valve 21 is attracted to the valve seat 20 according to the solenoid excitation current value.

Therefore, the closing force of the damping valve 12 is controlled according to the solenoid excitation current.

The passage 251 passing through the inside of the piston rod 6,
Specifically, it opens to the upper oil chamber 8 via an orifice 2G, and communicates with a valve chamber 27 defined below the solenoid 11 via an orifice 28. It communicates with the oil reservoir chamber 9 via.

The upper end of the piston rod 6 is fixed to the upper end of the thread/id 11 fixed inside the valve case 13 by a nut 311 via a washer 30 (however, as shown in the figure, it can also be connected by caulking. ).

A lead 1i40 connected to the coil 16 is taken out from the upper end of the solenoid 11, which is open to the atmosphere. The lead wire 40 passes through a cap 41 fitted to the upper part of the valve case 13, and is connected to the external drive circuit 53 described above.

Therefore, when the front 7 oak operates on the compression side, the contracted hydraulic oil in the lower oil chamber 7 expands through the check valve 5A of the piston 5 because the check valve (not shown) at the bottom of the cylinder closes. It flows into the upper oil chamber 8. The hydraulic oil corresponding to the volume entered by the piston rod 6 flows from the passage 25 of the piston rod 6 to the oil reservoir chamber 9 via the damping valve 12.

By the way, when the solenoid 11 is energized, the coil 16 is excited, and the excitation force causes the valve 21 to open (valve seat) 20
, and the damping valve 12 closes.

Therefore, for the hydraulic oil from the passage 25, the damping valve 12
A damping force is generated according to the valve closing force (valve opening pressure). This damping force changes depending on the excitation current value for the solenoid 11, and the damping force increases as the excitation force increases.

Next, when the front 7 oak moves to the extension side, the hydraulic oil in the upper oil chamber 8 contracts as the piston 5 rises.
Since the check valve 5A is closed, oil flows from the passage 25 of the piston rod 6 through the damping valve 12 to the oil sump chamber 9.

At the same time, the hydraulic oil in the annular passage 10 is sucked into the expanding lower oil chamber 7 from the check valve 4A at the bottom of the cylinder 4 without resistance.

Therefore, the damping force during the extension operation is also determined according to the opening degree of the damping valve 12, which is also controlled by the solenoid excitation current.

The operation including specific control operations in the controller 5 will be explained.

In the standard state (normal operating state) where the damping force is maintained at a constant value, the load characteristics of the shock absorber are such that the suspension spring constant and damping force characteristics that emphasize ride comfort are obtained, as shown by ABCDEF in Figure 4. settings.

On the other hand, in special operating conditions, A
As shown by B 'C'D E 'F', switch to a load characteristic that emphasizes maneuverability.

This switching is performed by the state sensor 4 that detects the operating state
! ! The determination is made based on the signal from the vehicle speed sensor 3 that detects.

In the standard state where the opening degree of the damping valve (rjl! valve pressure) is maintained at a constant value, the t1 shock absorber is approximately 1G5! If the operation starts from the (neutral position) on the compression side, the load is expressed as O since no damping force is generated when the shock absorber is not operating. Here, POQ indicates the characteristics of suspension springs such as metal and air springs.

When compression operation is started from this state, a pressure-side fluid reduction force is generated corresponding to the operation speed. If the operation speed is set to a certain value, the generated damping force is also constant, and from the operation start position to the maximum compression position (bottom dead center). ), the load changes from the spring characteristic plus a constant damping force, that is, from A to B.

When the operating direction changes from compression to extension, a reduction force on the extension side is generated. When this direction switches, the load is B
It is only after decreasing from to C that the buffer begins to operate in the extension direction. The extension damping force also has a constant value if the operating speed is constant, and the load decreases from C to E as it operates in the extension direction from the most compressed position. Passing the neutral position to the most extended position f? After reaching f (top dead center), the direction of displacement is reversed again and operation starts on the compression side, and the load changes from E to F, and then towards A, the IG (neutral) position. It will increase.

When the generated damping force is maintained at a constant value in this manner, the load characteristic of BCEF is adopted, which emphasizes riding comfort with a low spring constant (small inclination).

On the other hand, when driving at high speeds, cornering, accelerating, and decelerating, etc., when emphasis is placed on maneuverability, the damping force is variably controlled according to the displacement and direction of the shock absorber. It can be switched to have a special loan characteristic.

That is, based on the signals from the stroke sensor 1 and the 10th position detection sensor 6, as the displacement in the compression direction increases from the 10th position, the solenoid excitation current is gradually increased, and the opening degree of the damping valve is decreased (opened). Increase the valve pressure) to increase the damping force generated on the pressure side. Therefore, the load changes from A to B' until the maximum compression position is reached. When the displacement is reversed from the maximum compression position to the extension direction, the displacement speed becomes zero, so when this is detected by the damper speed sensor 2, the Tsuremade excitation current is reduced to a predetermined value smaller than the standard state, and the extension side Switch the damping force to a value lower than the standard value. Therefore, the load when starting the operation in the extension direction is C' which is higher than C in the standard state.

Then, as the displacement in the extension direction increases, the damping force is gradually increased, and at the 10th position, the damping force is returned to the standard state D. After the 10th position, the damping force is further increased to reach the maximum. In the extended position, the load becomes Eo, which is lower than E in the standard state.

When the displacement is reversed from the most extended position in the compression direction, the speed once becomes zero as described above, so at this time the damping force is switched to a value lower than the standard state. Therefore, the load at the start of compression is F', which is lower than F in the standard state. After the compression starts, the damping force is gradually increased toward the 10th position, and returns to the standard state at the 10th position.

As a result, the load characteristic becomes B'C'E'F', which is equivalent to the load characteristic BCEF in the standard state when the spring constant of the suspension spring is increased from POQ to P'OQ'.

Therefore, in reality, a suspension spring such as a metal spring or an air spring can be made to function as a variable hydraulic spring by variably controlling the damping force in accordance with the displacement and direction.

In addition, in this example, the damping force is returned to the standard state at the 10th position, and the magnitude of the damping force in the standard state and during variable control is made the same, but of course it can be made relatively higher or lower than the standard state depending on the request. You can do it like this.

Conventionally, there is a so-called position-dependent damping force control system that detects the stroke position of the shock absorber and increases the damping force according to the amount of displacement. Even if the force is increased according to the displacement, the damping force on the expansion/retraction side remains unchanged or increases in the same way, so the load decreases significantly when the direction of displacement changes from maximum compression to expansion. The expansion operation will not start until the compression operation is completed, and as a result, the delay toward the return side (expansion side) will become large, making it impossible to respond to the next compression operation.

In the case of the present invention, with respect to displacement from compression to extension, the suspension spring with an increased spring constant provides the same effect as a strong extension, so the response to the return side is There will be no problem of delays. This also applies when the direction of displacement is reversed from the most extended position to the compression direction, and compression is immediately started.

In this way, the present invention allows variable control of the spring constant and damping characteristics at the same time, which is different from simply increasing the reducing force depending on the stroke position. α is essentially different.

The value of the damping force that is controlled in accordance with the displacement and direction of the damper may be set to an optimum value that differs depending on the driving condition of the vehicle. Even though the load characteristics are focused on maneuverability, the required suspension characteristics vary slightly depending on the vehicle speed, acceleration/deceleration conditions, cornering conditions, etc., so these characteristics are based on the optimum characteristics determined experimentally in advance. The control circuit calculates the damping force control range at each time so that ill! All you have to do is go one step.

In other words, the rate of increase in damping force, the amount of increase, etc. can be changed according to the requirements for maneuverability. : Therefore, it is possible to control the apparent spring constant to be a little higher than the standard state, or to make it very high, and at the same time, the damping characteristics can be made soft or hard.

Specifically, by increasing the rate of increase in damping force, the spring constant becomes higher, and by increasing the amount of increase relatively, hard damping characteristics are obtained.

In addition, this explanation showed an example of changing the spring constant and damping characteristics at the same time, but by keeping the generated damping force consistent with the standard state and controlling only the rate of increase, only the apparent spring constant can be changed. You can also do it. Furthermore, by changing the rate of increase in the damping force midway through, it is possible to provide nonlinear spring characteristics in which the spring constant changes midway through.

In the above example, a common damping valve was used on the compression side and the rebound side, but
Each may be provided with an independent damping valve.

(Effects of the Invention) As described above, according to the present invention, by controlling the damping force on the extension side and the compression side in accordance with the displacement and direction of the shock absorber, the spring constant and the damping characteristic can be controlled simultaneously. This makes it possible to freely set suspension characteristics that satisfy ride comfort and handling stability, depending on the driving conditions of the vehicle. In addition, since spring control does not require any large driving force, the II
I control can be realized.

[Brief explanation of drawings]

The figures show an embodiment of the present invention. Fig. 1 is a configuration diagram, Fig. 2 is a flowchart showing an example of control operation, Fig. 3 is a sectional view of a shock absorber, and Fig. 4 shows suspension characteristics as a load. Characteristic diagrams shown based on the stroke; Figure 5 is a load (suspension) characteristic diagram for a general shock absorber with extremely slow displacement speed; Figure 6 is a load characteristic diagram for different displacement speeds; PIS7 Figure is a load characteristic diagram with emphasis on ride comfort,
FIG. 8 is a load characteristic diagram when emphasis is placed on maneuverability, and FIG. 9 is a moderate load characteristic diagram when ride comfort and maneuverability are taken into consideration. l... Stroke sensor, 2... Damper speed sensor, 3... Vehicle speed sensor, 4... Driving state sensor, 5...
...Controller, 6...Bow G sensor, 8...
damping valve.

Claims (1)

[Scope of Claims] 1. means for detecting the displacement of the shock absorber, means for determining the compression side stroke and the rebound side stroke from the detected displacement, and means for adjusting the compression side damping force and the rebound side damping force, respectively; control means for driving the adjusting means so that in the compression stroke, the generated damping force is increased as the damping force is displaced in the maximum compression direction, and in the extension stroke, the generated damping force is increased as the displacement is in the maximum extension direction; A control device for a hydraulic shock absorber. 2. A control device for a hydraulic shock absorber according to claim 1, characterized in that means for determining an operating state is provided, and the control means is operated in accordance with the operating state.