JP2002257179A - Hydraulic buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain desired effect as preset by means of selection of hardware and software while damping force on an extension side as well as on a compression side can be controlled. SOLUTION: A control valve 10 performing switching operation by means of inputting and releasing external signals is arranged in a bottom portion 5 of a cylinder body 1. The control valve 10 is connected with an oil passage L formed between an intermediate tube 9 and inner tube 4 that form the cylinder body 1 and a reserving chamber R in which a pressurized chamber R2 within the inner tube 4 forming the cylinder body 1 is formed between an outer tube 3 and the intermediate tube 9 via orifices 12b and 12c, or this connection is connected with the control valve 10 while this connection is shut off. The end of an opening of a port 15 being open to the reserving chamber R is blocked openably and closably by means of a sub-valve 20 which is released when hydraulic pressure from the control valve 10 acts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic shock absorber, and more particularly, to an improvement in a hydraulic shock absorber capable of controlling a generated damping force to a high level and a low level.

[0002]

2. Description of the Related Art For example, it is preferable that a hydraulic shock absorber mounted on a vehicle to absorb road surface vibration can control the generated damping force to a high level and a low level. Various types of hydraulic shock absorbers have been proposed.

Among them, for example, the hydraulic shock absorber shown in FIG. 2 has a control valve 10 at a bottom portion of the cylinder body 1, and the switching operation of the control valve 10 increases or decreases the compression side damping force. It is stated that control, that is, selection of hardware and software of the compression side damping force can be realized.

[0004] To briefly explain, first, it is assumed that the hydraulic shock absorber is configured such that a rod body 2 is inserted into and retractable from a cylinder body 1. Having.

[0005] Then, the lower ends of the outer cylinder 3 and the inner cylinder 4 are sealed with a bottom member 5 constituting the above-mentioned bottom portion.
The upper end of the inner cylinder 4 constitutes a head portion of the cylinder body 1 and is sealed with a head member 6 that allows the rod body 2 to penetrate the shaft core.

[0006] A reservoir chamber R is provided between the outer cylinder 3 and the inner cylinder 4, and the reservoir chamber R has a gas chamber G bounded by an oil level O.

A piston 7 connected to the lower end of the rod body 2 is slidably housed in the inner cylinder 4, and the piston 7 allows the extension side chamber R 1 and the compression side chamber to be accommodated in the inner cylinder 4. R2 is defined.

Further, the piston 7 is provided with an expansion-side damping valve 7a and a compression-side damping valve 7b.
When the oil No. 1 flows out to the compression side chamber R2 through the extension side damping valve 7a, the oil in the pressure side chamber R2
It is stated that a damping force having a valve characteristic having a predetermined magnitude is generated when the gas flows out to the extension side chamber R1 through the b.

Further, a pressure-side damping valve 8a constituting the base valve 8 and a pressure-side check valve 8b arranged in parallel with the base valve 8 are arranged in the bottom member 5, that is, at the bottom of the cylinder body 1.

Therefore, in this hydraulic shock absorber, when the oil in the pressure side chamber R2 passes through the pressure side damping valve 8a and flows out to the reservoir chamber R, the oil pressure in the pressure side damping valve 7b provided in the piston 7 is equal to that of the pressure damping valve 7b. In this way, a pressure-side damping force having a valve characteristic having a predetermined magnitude is generated.

On the other hand, the control valve 10 has a communication position 12 maintained by the urging force of the urging spring 11, and a solenoid 13.
When the switch position is in the communication position 12, the communication between the pressure side chamber R2 and the reservoir chamber R is permitted. When the switch position is switched to the cut off position 14, the pressure side chamber R2 and the reservoir chamber are switched. It is stated that communication of R is blocked.

Incidentally, in the control valve 10, the communication position 12 has a throttle 12a, so that when the control valve 10 is in the pressure side when the control valve 10 is in the communication position 12, a so-called hydraulic pressure is established in the pressure side chamber R2. And the extension side chamber R
In No. 1, care is taken not to cause an oil supply shortage.

Therefore, when the control valve 10 is located at the communication position 12 shown in the drawing, a bypass passage is formed in parallel with the base valve 8, and therefore, the oil in the pressure side chamber R2 is discharged. , Can flow out into the reservoir chamber R without passing through the pressure-side damping valve 8 a constituting the base valve 8.

As a result, the control valve 10 is set to the communication position 1
Even if this hydraulic shock absorber operates on the compression side in the state of 2, the damping force generated at that time is smaller than when the oil in the compression side chamber R2 flows out to the reservoir chamber R via the compression side damping valve 8a. The damping force becomes low, and a so-called soft damping force is generated.

On the other hand, when the control valve 10 is switched to the shut-off position 14 (not shown), there is no so-called bypass path, so that the oil in the pressure side chamber R2 flows out to the reservoir chamber R via the pressure side damping valve 8a. Will do.

As a result, the control valve 10 is switched to the shut-off position 1
4, the damping force when the hydraulic shock absorber operates on the compression side becomes so high as to be set by the compression side damping valve 8a, so that a so-called hard damping force is generated.

As a result, in the vehicle on which the hydraulic shock absorber is mounted, the switching control of the control valve 10 is appropriately performed for each of the hydraulic shock absorbers disposed in each of the four wheels, so that the generation damping during the pressure-side operation is reduced. By making the force high and hard, for example, the occurrence of a nose dive phenomenon when the vehicle suddenly brakes and a squat phenomenon when the vehicle suddenly starts can be prevented.

Further, a vehicle on which the hydraulic shock absorber is mounted is
For example, when traveling on a flat road at high speed, the control valve 10
Is maintained at the communication position 12, the compression-side damping force is maintained at a low and soft level, and the ride comfort of the vehicle can be maintained in a favorable state.

[0019]

However, in the above-mentioned hydraulic shock absorber, there is a problem that only the damping force at the time of the compression side operation can be controlled, and the damping force at the time of the extension side operation cannot be controlled. Of course, there is a problem that the desired effect cannot be obtained even if the damping force at the time of the pressure side operation is controlled to be high or low.

That is, in the above-mentioned hydraulic shock absorber,
In the communication position 12, the control valve 10
a, so-called oil pressure is raised in the compression-side chamber R2 when the hydraulic buffer is operated on the compression side, in which the piston 7 descends in the inner cylinder 4, so that insufficient oil supply does not occur in the expansion-side chamber R1. I am careful.

Therefore, in the control valve 10, the opening of the throttle 12a at the communication position 12 cannot be increased.

As a result, when the control valve 10 is in the communication position 12 during the operation of the hydraulic shock absorber on the pressure side, a damping force having a square characteristic is generated by the throttle 12a.

Therefore, when the control valve 10 is in the shut-off position 14 during the same pressure side operation, the difference between the damping force of the valve characteristics generated by the pressure side damping valves 8a and 7b becomes small, and the hardware There is a problem that the difference in ride comfort is reduced.

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to control the level of the generated damping force, thereby enabling not only the compression side but also the extension side. Needless to say, it is an object of the present invention to provide a hydraulic shock absorber which is optimal for expecting an improvement in versatility by enabling a desired effect to be obtained as selected by selecting hardware and software.

[0025]

Means for Solving the Problems To achieve the above-mentioned object, according to the present invention, basically, a cylinder body into which a rod body is inserted so as to be able to protrude and retract has an intermediate cylinder inside an outer cylinder. An inner cylinder is provided inside the intermediate cylinder, and a space between the outer cylinder and the intermediate cylinder is set as a reservoir chamber, and a space between the intermediate cylinder and the inner cylinder is set as an oil passage. A piston slidably housed in the inner cylinder defines an extension side chamber and a compression side chamber in the inner cylinder, and the extension side chamber and the compression side chamber are connected via an extension side damping valve and a compression side damping valve disposed on the piston. The hydraulic shock absorber is configured such that the pressure side chamber and the reservoir chamber can communicate with each other via a pressure side damping valve disposed at the bottom portion of the cylinder body and a pressure side check valve arranged in parallel with the pressure side damping valve. External signal input and While the control valve switches between the oil passage and the pressure side chamber to the reservoir chamber or selects the communication to the reservoir chamber through the throttle, It is assumed that an opening end of a port communicating with the control valve and opening to the reservoir chamber is opened and closed by a sub-valve that opens when a hydraulic pressure is applied from the control valve.

In the above structure, more specifically, it is assumed that the sub-valve is disposed in a cutout formed in a side surface of the bottom member forming the bottom portion. And a leaf valve for improving the supply of oil to the expansion side chamber by setting the compression side chamber to a predetermined pressure state while keeping the cracking pressure smaller than the cracking pressure in the compression side damping valve.

Incidentally, it is assumed that the extension damping valve and the compression damping valve arranged on the piston and the compression damping valve arranged on the bottom portion are set to generate damping force having valve characteristics.

It is preferable that an actuator for activating the control valve by an external signal is held on the outer periphery of the bottom portion.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on the illustrated embodiment. However, the hydraulic shock absorber according to the present invention is similar to the conventional hydraulic shock absorber shown in FIG. It has a configuration.

Therefore, parts having the same structure as that shown in FIG. 2 are denoted by the same reference numerals in the figure, and detailed description thereof will be omitted except where necessary. The following description focuses on the features of the present invention.

However, in the hydraulic shock absorber according to the present invention, the cylinder body 1 has an intermediate cylinder 9 between the outer cylinder 3 and the inner cylinder 4 as shown in FIG. 3 and the intermediate cylinder 9 are set in the reservoir chamber R, while the intermediate cylinder 9
And the inner cylinder 4 is set as an oil passage L.

The oil passage L communicates with a control valve 10 to be described later, while, as shown in the drawing, an extension side chamber R1 defined in the inner cylinder 4 through an oil passage L1 formed in the head member 6. To communicate with

The control valve 10 is arranged at the bottom portion of the cylinder body 1 and is set so as to be switched when an external signal is input and released. It is set so that not only the communication cutoff of the oil passage L formed between the inner cylinder 9 and the inner cylinder 4 to the reservoir chamber R can be selected, but also the communication cutoff of the pressure side chamber R2 and the oil passage L can be selected. ing.

That is, when the control valve 10 is in the communication position 12, the pressure side chamber R2 and the oil passage L communicate with the reservoir chamber R, while the pressure side chamber R2 and the oil passage L communicate with each other. On each route, an aperture 12
b and 12c are provided.

When the control valve 10 is in the shut-off position 14, the control valve 10 cuts off the communication between the pressure side chamber R2 and the oil passage L to the reservoir chamber R and also cuts off the communication between the pressure side chamber R2 and the oil passage L. I have to.

In the control valve 10, although not shown, an actuator for activating the control valve by an external signal is held on the outer periphery of the bottom member 5 constituting the bottom portion. In the hydraulic shock absorber, compared to a case where this type of actuator is continuously provided at the upper end of the rod body 2 or the lower end of the cylinder body 1, that is, the lower end of the bottom member 5, the axial direction of the hydraulic shock absorber This is advantageous in that the length is not increased.

On the other hand, in this hydraulic shock absorber, a port 1 is connected to the control valve 10 and opens to the reservoir chamber R.
At the open end of 5, the pressure side chamber R2 is brought into a predetermined pressure state,
In other words, the sub-valve 20 for bringing the compression-side chamber R2 to a predetermined pressure state so as not to cause a shortage of oil supply to the expansion-side chamber R1 during the compression-side operation is provided adjacently.

Therefore, by setting the sub-valve 20 so as to realize the above-mentioned predetermined pressure state, even if the opening degree of the throttle 12b is increased, the oil supply in the expansion side chamber R1 during the pressure side operation may be insufficient. Will not be invited.

At this time, the sub-valve 20 is specifically arranged in a notch 5a formed on the side surface of the bottom member 5.

The sub-valve 20 is connected to the port 1
5 is provided with a leaf valve 21 for opening and closing the open end of the leaf member 5. The leaf valve 21 has a so-called fixed end fixed to the bottom member 5 with a screw 22 as an appropriate fixing means.

Therefore, in the sub-valve 20, the design change required for disposing the sub-valve 20 in the hydraulic shock absorber is, in principle, sufficient for the bottom member 5 forming the bottom portion. This is advantageous in that it does not cause unnecessarily high cost due to the design change.

The sub-valve 20 is opened when the hydraulic pressure from the control valve 10 acts on the rear surface of the leaf valve 21 via the port 15 when the pressure becomes a predetermined pressure. Conversely, when the pressure inside the port 15 tends to be negative, the leaf valve 21 is closed to prevent the oil from the reservoir chamber R from flowing to the control valve 10 side.

As described above, in the control valve 10, even if the throttle 12b is provided in the communication position 12 and is provided on the route from the compression side chamber R2, the expansion valve R1 is not operated when the compression side is operated as in the conventional example. Since there is no shortage of oil supply, there is a fear of this shortage of oil.
There is no need to select the opening of b.

In the hydraulic shock absorber formed as described above, a predetermined damping force is generated as follows.

That is, first, when the piston 7 descends in the inner cylinder 4 while the control valve 10 remains at the communication position 12, a part of the oil in the pressure side chamber R 2 is removed from the communication position 12 of the control valve 10. And the oil flow through the oil passages L, L1 to the extension side chamber R1.
Since the pressure side chamber R2 is brought into a predetermined pressure state by disposing the sub-valve 20, there is no need to worry about insufficient oil supply in the expansion side chamber R1.

At this time, an excess amount of oil corresponding to the rod invading volume integral in the pressure side chamber R2 flows out to the reservoir chamber R via the throttle 12b and the sub-valve 20, and the pressure side damping constituting the base valve 8 Valve 8a
Can not pass.

At this time, the flexural rigidity of the leaf valve 21 constituting the sub-valve 20 is set to be small in order to only bring the compression-side chamber R2 into a predetermined pressure state so as not to cause insufficient oil supply to the expansion-side chamber R1. , And the aperture 12b is
As compared with the conventional throttle 12a (see FIG. 2), even if the opening degree is increased, the supply of oil to the expansion side chamber R1 will not be insufficient, so that the so-called low pressure side damping force, that is, the soft A state in which a large compression side damping force is generated.

On the other hand, when the piston 7 moves up in the inner cylinder 4 while the control valve 10 is at the same communication position 12, the oil from the expansion chamber R1 is supplied to the oil passage L.
1, L and the throttle valve 12b, 12c of the control valve 10 flow out to the pressure side chamber R2, so that the oil does not pass through the expansion side damping valve 7a provided in the piston 7.

As a result, the generation of the so-called high damping force by the extension-side damping valve 7a cannot be expected, and a low extension-side damping force, that is, a soft extension-side damping force is generated.

Incidentally, at this time, an amount of oil corresponding to the rod retreating volume integral, which is insufficient in the pressure side chamber R2, is supplied from the reservoir chamber R via the pressure side check valve 8b constituting the base valve 8. Become.

Next, although not shown, when the control valve 10 switches to the shut-off position 14, the so-called bypass path is shut off.

Therefore, in this state, at the time of the compression side operation in which the piston 7 descends in the inner cylinder 4, a part of the oil in the compression side chamber R2 is transferred to the expansion side chamber R1 via the compression side damping valve 7b provided in the piston 7. At the same time, the excess oil in the pressure side chamber R2 flows out to the reservoir chamber R via the pressure side damping valve 8a constituting the base valve 8, and the pressure side damping valve 7
When the oil passes through b and 8a, a predetermined so-called high pressure-side damping force, that is, a hard pressure-side damping force is generated.

When the piston 7 moves up in the inner cylinder 4, the oil in the expansion side chamber R1 flows out to the compression side chamber R2 via the expansion side damping valve 7a provided in the piston 7, and the compression side chamber R1. Insufficient oil in R2 flows from the reservoir chamber R through the pressure side check 8b constituting the base valve 8, and the oil passes through the expansion side damping valve 7a, so that a predetermined so-called high expansion side attenuation is obtained. A force, that is, a hard extension damping force is generated.

Therefore, in the illustrated hydraulic shock absorber, in the vehicle on which the hydraulic shock absorber is mounted, the control valve 10 is switched for each of the hydraulic shock absorbers disposed in each part of the four-wheels, so that the pressure side is changed. When the generated damping force at the time of operation is made high and hard, for example, the occurrence of a nose dive phenomenon when the vehicle suddenly brakes and a squat phenomenon when the vehicle suddenly starts can be prevented beforehand. .

The vehicle on which the hydraulic shock absorber is mounted is:
For example, when traveling on a flat road at high speed, the control valve 1
By maintaining 0 as the communication position 12, the compression-side damping force can be maintained at a low and soft level, and the riding comfort of the vehicle can be maintained in a good state.

[0056]

As described above, in the hydraulic shock absorber according to the present invention, the generated damping force can be adjusted not only at the time of the compression side operation but also at the time of the extension side operation. Not only can the damping force be selected according to the running conditions of the vehicle, but the vehicle, for example,
When traveling on a flat road at high speed, the compression side damping force can be maintained at a low and soft level, and the ride comfort of the vehicle can be maintained in a good state. Thus, even when the hydraulic shock absorber operates at a high speed on the compression side, a high compression-side damping force is not generated even instantaneously, and a soft ride comfort in the vehicle can be maintained.

According to the present invention, since the sub-valve is disposed in the cutout formed in the side surface of the bottom member forming the bottom portion, in principle, the design in the bottom member described above is performed. The change is sufficient, which is advantageous in that it does not lead to unnecessarily high costs associated with the design change.

Further, by providing the sub-valve, the pressure side chamber is brought into a predetermined pressure state at the time of the pressure side operation, ie, it is possible to prevent shortage of oil supply to the expansion side chamber at the time of the pressure side operation. , It is possible to provide a throttle with a large opening area in the route leading to the compression side chamber, so that the compression side damping force during high-speed compression side operation can be provided with a difference that can be clearly distinguished by selecting hardware and software become.

As a result, according to the present invention, in controlling the level of the generated damping force in the hydraulic shock absorber, not only the compression side but also the extension side is made possible, and the selection of hardware and software is made possible. A desired effect can be obtained as set, which is optimal for expecting improvement in versatility of the hydraulic shock absorber.

[Brief description of the drawings]

FIG. 1 is a principle view of a hydraulic shock absorber according to an embodiment of the present invention, which is partially cut away.

FIG. 2 is a view showing a hydraulic shock absorber as a conventional example, similarly to FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder body 2 Rod body 3 Outer cylinder 4 Inner cylinder 5 Bottom member 5a which constitutes the bottom part in a cylinder body 5a Notch 6 Head member which constitutes a head part in a cylinder body 7 Piston 7a Extension damping valve 7b, 8a Pressure damping valve Reference Signs List 8 Base valve 8b Pressure side check valve 9 Intermediate cylinder 10 Control valve 11 Energizing spring 12 Communication position 12b, 12c Restrictor 13 Solenoid 14 Shut off position 15 Port 20 Sub-valve 21 Leaf valve 22 Screw as fixing means G Gas chamber L, L1 Oil passage O Oil surface R Reservoir room R1 Extension side room R2 Pressure side room

Claims (3)

[Claims] A cylinder body through which a rod body is inserted so as to be able to protrude and retract has an intermediate cylinder inside the outer cylinder and an inner cylinder inside the intermediate cylinder, and a reservoir chamber is provided between the outer cylinder and the intermediate cylinder. At the same time, set the oil passage between the intermediate cylinder and the inner cylinder,
A piston connected to the lower end of the rod body and slidably housed in the inner cylinder defines an extension side chamber and a compression side chamber in the inner cylinder, and the extension side chamber and the compression side chamber are disposed on the piston. It is possible to communicate with the damping valve via the compression side damping valve, and the communication between the compression side chamber and the reservoir chamber via the compression side damping valve arranged at the bottom portion of the cylinder body and the pressure side check valve parallel to the compression side damping valve. In the hydraulic shock absorber of the present invention, a control valve is provided at the bottom for switching operation by inputting and releasing a signal from the outside, and the control valve cuts off communication between the oil passage and the pressure side chamber to the reservoir chamber. Alternatively, while choosing to communicate with the reservoir through a throttle,
A hydraulic shock absorber characterized in that an opening end of a port communicating with the control valve and opening to the reservoir chamber is openably and closably closed by a sub-valve that opens when a hydraulic pressure is applied from the control valve. 2. The hydraulic shock absorber according to claim 1, wherein the sub-valve is disposed in a notch formed in a side surface of the bottom member forming the bottom. 3. A sub-valve having a leaf valve which has a cracking pressure smaller than a cracking pressure of a pressure side damping valve disposed at a bottom portion and has a valve opening larger than a valve opening of the pressure side damping valve. Hydraulic shock absorber according to 1