JPH05231463A - Shock absorber - Google Patents

Abstract

PURPOSE:To prevent the number of members and weight from being increased by disposing a pilot upstream valve and a pilot downstream valve at a pilot passage to lead oil pressure between both valves to the back face side of a damping valve, and forming an orifice for generating first-order lag oil pressure, at the pilot upstream valve. CONSTITUTION:In a low oscillation frequency region, first-order lag oil pressure is supplied as back pressure to an expanding side pressure chamber R1 on the back face side of an expanding side damping valve 10 through the orifice 12a of a pilot upstream valve 12 in a pilot passage, so that the oil pressure on the pressure receiving face side of the valve 10 rises. The oil pressure of the valve 12 also rises to open the valve 12, and back face pressure to the valve 10 further rises to obtain high damping force. In a medium oscillation frequency region, operating oil cannot pass easily through the orifice 12a, nor the first-order lag oil pressure is supplied to the pressure chamber R1, so that damping force is stopped low. In a high oscillation frequency region, the valve 12 is opened by the bending of the outer peripheral end, and back pressure acts upon the back face of the valve 10 to obtain high damping force. With this constitution, there is no need to provide an oscillation frequency sensing valve so as to prevent increase in the number of part items.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a vibration frequency-dependent shock absorber which is optimal for mounting on a vehicle or the like.

[0002]

2. Description of the Related Art As shock absorbers mounted on vehicles and the like, various shock absorbers have been proposed so far, but in recent years, the generated damping force is changed depending on the vibration frequency. A structure having a structure is proposed.

For example, in a shock absorber disclosed in Japanese Utility Model Publication No. 63-11401, a compression side damping valve provided in a base valve portion of a cylinder is designed to generate a predetermined damping force during its operation. On the other hand, depending on the vibration frequency in the cylinder,
It is formed so that the initial load on the compression side damping valve is changed.

That is, in the above-mentioned conventional shock absorber, the compression side damping valve is composed of an annular leaf valve, and the inner peripheral end of the annular leaf valve valve serves as a bending end, and The lower end of the push member that descends due to the first-order hydraulic action is abutted.

The hydraulic pressure from the upstream side of the compression side damping valve is supplied as a primary delay hydraulic pressure by passing through the orifice to the pressure chamber defined on the upper surface side of the push member.

Therefore, according to this conventional shock absorber, the vibration frequency in the cylinder is from 1 to 1.
When the vibration frequency is in the low vibration frequency range of about 2 Hertz, a primary delay hydraulic pressure is supplied to the pressure chamber, and the push member descends due to the primary delay hydraulic action so that its lower end is pressed against the inner peripheral end of the annular leaf valve. As a result, the initial load at the inner peripheral end of the annular leaf valve is changed, and a high damping force can be generated.

When the vibration frequency in the cylinder exceeds the low vibration frequency range, the hydraulic effect of the first-order lag is canceled and the push member is not lowered. As a result, at the inner peripheral end of the annular leaf valve valve. After the initial load is returned to the initial setting, after that, the lower damping force is generated as compared with the above high damping force, that is, the so-called high cut phenomenon is exhibited.

Therefore, according to the above-mentioned conventional shock absorber, a high damping force is generated near the sprung resonance point where the vibration frequency in the cylinder is in the low vibration frequency region, and vibration suppression on the spring in the vehicle is possible. At the same time, when the vibration frequency in the cylinder is in the low vibration frequency range or higher, a low damping force is generated and the riding comfort of the vehicle is improved.

[0009]

However, in the above-mentioned conventional shock absorber, it is impossible to suppress the vibration in the vicinity of the unsprung resonance point, and it is not possible to secure the grounding property of the vehicle.

That is, in the shock absorber as the above-mentioned conventional example, it is the orifice that generates the hydraulic pressure of the first order lag, and the orifice is a so-called fixed orifice.

Therefore, if the diameter of the orifice is set so as to fit in the low vibration frequency region for damping on the spring,
It becomes impossible to use the orifice above the low vibration frequency region, and as a result, it is impossible to generate a hydraulic oil with a first-order lag particularly in the high vibration frequency region near the unsprung resonance point.

As a result, in the above-mentioned conventional shock absorber, it becomes impossible to generate a high damping force in the high vibration frequency region near the unsprung resonance point, and the unsprung portion of the vehicle suppresses a so-called flap phenomenon. It will not be possible.

Of course, while the so-called high-cut valve described above is installed in the shock absorber, the so-called low-cut valve formed so as to generate a high damping force near the unsprung resonance point may also be installed in the shock absorber. For example, a high damping force is generated in the high vibration frequency region to enable the unsprung vibration to be suppressed, and the unsprung in the vehicle can suppress the flap phenomenon.

However, if the vibration frequency sensitive valves are provided for damping the unsprung part and the unsprung part, the number of members is increased and the overall weight of the shock absorber and the product cost are increased. It is not preferable because it is caused.

Further, even if a high damping force is generated near the unsprung resonance point by the low-cut valve, as long as the vibration frequency in the cylinder is in the high vibration frequency region, it is still high even after passing the unsprung resonance point. A damping force is generated, which rather causes a disadvantage that the riding comfort of the vehicle is deteriorated.

The present invention was devised in view of the present situation as described above, and the purpose thereof is, of course, to enable predetermined unsprung and on-spring damping,
An object of the present invention is to provide a shock absorber that is most suitable for mounting on a vehicle without causing an increase in the total weight and an increase in product cost due to an increase in the number of unnecessary members.

[0017]

In order to achieve the above-mentioned object, the structure of the present invention is used to generate a predetermined damping force by a damping valve provided in the piston portion when the piston portion slides in the cylinder. At the same time, the hydraulic pressure depending on the vibration frequency in the cylinder is guided to the back side of the damping valve through a pilot flow path branched and extended from the pressure receiving surface side of the damping valve to open the damping valve with respect to the upstream pressure. In a shock absorber formed so as to be able to change
A pilot upstream valve consisting of a leaf valve and a pilot downstream valve consisting of a leaf valve are arranged in the pilot flow path, and the oil pressure between the pilot upstream valve and the pilot downstream valve is guided to the back side of the damping valve. It is assumed that an orifice is formed in the pilot upstream valve to generate a hydraulic pressure with a primary delay.

[0018]

Therefore, when the vibration frequency in the cylinder is in the low vibration frequency region of about 1 to 2 hertz, a predetermined amount is provided through the orifice opened in the pilot upstream valve provided in the pilot passage. The first-order lag hydraulic pressure is supplied to the back side of the damping valve, and the damping valve is backed up.

Since the hydraulic pressure on the pressure receiving surface side of the damping valve is increased by the backup, the hydraulic pressure acting on the pilot upstream valve is increased, the pilot upstream valve is opened, and the hydraulic pressure on the rear side of the damping valve is further increased. As a result, the backup force in the damping valve becomes large, and the damping force generated in the damping valve becomes high damping force.

When the vibration frequency in the cylinder is in the medium vibration frequency range of 3 to 8 Hertz, it becomes difficult for the working oil to pass through the orifice, so that the hydraulic pressure of the first order lag is not supplied to the back side of the damping valve.

As a result, the backup force in the damping valve is canceled, the initial load in the damping valve is maintained at the initial setting, and low damping force is generated.

Further, when the vibration frequency in the cylinder is in the high vibration frequency range of 9 hertz or more, the pilot upstream valve is apparently closed, but the hydraulic oil acting on the pilot upstream valve is apparently closed. The pilot upstream valve is opened due to an increase in inertial force.

As a result, the pilot flow in the pilot channel is secured, and the damping force generated by the damping valve is made high damping force as in the case of the low vibration frequency region described above.

When the vibration frequency in the cylinder is in the ultra-high vibration frequency range, the opening / closing of the pilot upstream valve due to the inertial force of oil cannot follow the input due to its own response delay, and as a result, the damping valve As a result, it becomes impossible to build up the backup force of the above, and the damping force generated by the damping valve is gradually reduced.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a shock absorber according to an embodiment of the present invention is inserted into a cylinder 1 under a shaft-sealing structure so that the shock absorber can be retracted and retracted. Lower end spigot 2a of piston rod 2
While the piston portion 3 held by the cylinder 1 is slidably accommodated in the cylinder 1, the expansion side chamber A and the compression side chamber B are accommodated in the cylinder 1.
And are divided into sections.

The piston part 3 has an expansion side damping valve 10 as a damping valve for generating a predetermined expansion side damping force during the expansion side stroke in which the piston part 3 rises in the cylinder 1, and the piston part 3 moves inside the cylinder 1. And a compression side damping valve 20 as a damping valve that generates a predetermined compression side damping force during the descending compression side stroke.

Incidentally, the expansion side damping valve 10 is composed of an annular leaf valve, and constitutes the piston portion 3 of the piston body 3.
0 is arranged so as to close the lower end opening of the expansion side port 30a of the perforation, and the compression side damping valve 20 is also an annular leaf valve.
It is arranged so as to close the upper end opening of 0b.

The expansion side port 30a is oblique to the piston body 30 via an annular groove 30c formed in the lower end surface of the piston body 30 so as to face the pressure receiving surface of the expansion side damping valve 10. And is communicated with a sub port 30d opened at the inner periphery of the piston body 30.

The pressure side port 30b also has an annular groove 30e formed in the upper end surface of the piston body 30 so as to face the pressure receiving surface of the pressure side damping valve 20.
When the piston body 30 is obliquely opened, the piston body 30
Is communicated with the sub-port 30f which is open to the inner circumference of.

By the way, in the present invention, the expansion side pressure chamber R1 and the compression side pressure chamber R2, which are back pressure chambers, are formed on the respective back sides of the expansion side damping valve 10 and the compression side damping valve 20. However, the hydraulic pressure is supplied to the pressure chambers R1 and R2 on the respective sides through the pilot flow passages on the respective sides.

Therefore, the structure of the pilot flow passage on each side will be described. The structure of the pilot flow passage on each side is basically the same structure. Only the structure of the pilot channel is described, and the structure of the pilot channel on the pressure side is only indicated as necessary, and the detailed description thereof is omitted.

Incidentally, the sub-ports 30d and 30f opened in the piston body 30 are also the parts constituting the pilot flow passage on each side.

First, an inner hollow portion 2c is formed in the shaft core portion of the piston rod 2 from the lower end spigot portion 2a to the lower end threaded portion 2b so that the lower end is opened to the pressure side chamber B. , A valve seat member 11 for expansion, a valve seat member 21 for compression, and a partition member 40 arranged so as to be sandwiched between the valve seat members 11 and 21 in the inner space 2c. Are arranged.

Between the partition member 40 and each of the valve seat members 11 and 21, there are arranged pilot upstream valves 12 and 22 each of which is a leaf valve and used for the pilot flow passage on each side. ing.

Incidentally, pins 13 and 23 are arranged between the partition wall member 40 and the valve seat members 11 and 21, and the pilot upstream valves 12 and 22 are connected to the pins 13 and 23. Will be installed.

The pilot upstream valves 12,
As shown in FIG. 2, an orifice 12a (a pilot upstream valve 2 for the pressure side is provided with an orifice 12a so as to penetrate its thickness.
The second orifice is not shown) and the orifice 12a functions as a first-order lag hydraulic pressure in the expansion side pressure chamber R1.

Next, as shown in FIG. 2, the inner peripheral end of the extension side damping valve 10 and the inner peripheral side lower end of the piston body 30 are
The lower end thread portion 2 of the piston rod 2 is arranged so as to face this.
It is sandwiched between the upper end of the piston nut 31 screwed to b and the fixed end, so to speak.

On the other hand, the outer peripheral end of the expansion side damping valve 10 is adjacent to the outer peripheral side lower end of the piston body 30, and is an annular valve arranged on the upper peripheral side of the piston nut 31. The upper end of the seat member 14 is abutted against the lower end of the piston body 30 on the outer peripheral side.

That is, since the valve seat member 14 is constructed so as to be movable by being urged by the urging force from the urging spring 15 disposed at the lower end of the valve seat member 14, the outer periphery of the extension side damping valve 10 is The end is set to the flexible end.

On the other hand, the valve seat member 14 has an annular gap 14a as a flow path on the inner peripheral side thereof between the upper end side of the piston nut 31 and the outer peripheral side thereof, and the outer periphery thereof is Is slidably contacted with the inner circumference of the upper end of the annular housing member 16 disposed adjacent to the.

The housing member 16 has a port 16b formed in the partition wall 16a formed on the lower side thereof, and the gap 14a serving as the flow path is provided in the port 16b.
The pressure side chamber B can be communicated via b.

Further, at the lower end of the housing member 16, a pilot downstream valve 1 formed of an annular leaf valve so as to close the lower end opening of the port 16b.
7 are provided.

Incidentally, the pilot downstream valve 17 has its inner peripheral end clamped between the lower end of the inner peripheral side of the housing member 16 and the lower end side of the piston nut 31 with a washer 32 interposed therebetween. At the same time, the outer peripheral edge is adjacent to the outer peripheral side lower end of the housing member 16 to form a flexible edge.

By the way, the lower end spigot portion 2a of the piston rod 2 is provided with upper and lower two-stage communication holes 2d and 2e which are opened so as to penetrate through the thickness thereof in the radial direction. The communication hole 2d communicates with the subport 30d formed in the piston body 30, and also communicates with the annular groove 40a formed on the outer periphery of the partition member 40.

The annular groove 40a is communicated with a port 40b for opening the partition wall member 40, and the port 40b
Communicates with the pressure receiving surface side of the pilot upstream valve 12 arranged at the lower end of the partition member 40 so as to close the lower end opening.

Incidentally, the pilot upstream valve 12 has its inner peripheral end sandwiched between the inner peripheral lower end of the partition wall member 40 and the inner peripheral upper end of the valve seat member 11 to be a fixed end. At the same time, its outer peripheral edge is adjacent to the lower peripheral edge of the partition wall member 40 to form a flexible end.

On the other hand, on the outer periphery of the upper end side of the valve seat member 11, there is provided a space portion 11a which is formed by cutting out the space portion 11a, and the space portion 11a is provided with operating oil through the pilot upstream valve 12. And the lower end inlay portion 2a of the piston rod 2 is communicated with the lower communication hole 2e.

The communicating hole 2e is opposed to the communicating hole 31a which is opened at the upper end side of the piston nut 31, and the communicating hole 31a is the communicating hole 31a.
4 is communicated with the annular gap 14a as a flow path formed on the inner peripheral side.

As a result, the expansion side pilot flow passage has a sub-port 30d communicating with the annular groove 30c, a communicating hole 2d opened in the piston rod 2, an annular groove 40a and a port 40b formed in the partition member 40, a valve seat. The space 11a formed in the member 11 and the communication hole 2 opened in the piston rod 2
e, a communication hole 31a opened in the piston rod nut, an annular gap 14 formed on the inner peripheral side of the valve seat member 14
a and a port 16a formed in the housing member 16.

A pilot upstream valve 12 is provided upstream of the expansion-side pilot passage formed as described above, and a pilot downstream valve 17 is provided downstream of the pilot passage. As a result, the extension side pressure chamber R1 is formed between the pilot upstream valve 12 and the pilot downstream valve 17.

Therefore, since the expansion side pressure chamber R1 is formed as described above, according to the present invention, the expansion of the piston body 30 occurs during the expansion side stroke in which the piston portion 3 rises in the cylinder 1. A main flow for supplying hydraulic oil to the pressure receiving surface side of the expansion side damping valve 10 via the side port 30a and a pilot flow for supplying a predetermined hydraulic pressure to the expansion side pressure chamber R1 occur. You will get it.

The relationship between the main flow and the pilot flow is as follows depending on the vibration frequency range in the cylinder 1.

First, when the vibration frequency is in the low vibration frequency region of about 1 to 2 hertz, the orifice 12a opened in the pilot upstream valve 12 disposed in the pilot flow path.
1st delay hydraulic pressure as a back pressure via expansion side damping valve 1
It is supplied to the extension side pressure chamber R1 which is the back side of 0.

Therefore, the expansion side damping valve 10 is so-called backed up by the back pressure acting on the rear surface side thereof, and the hydraulic pressure on the pressure receiving surface side of the expansion side damping valve 10 is increased.

As a result, along with this, the hydraulic pressure acting on the pilot upstream valve 12 also rises, the pilot upstream valve opens, and the back pressure to the extension side damping valve 10 further rises. The backup power increases.

Therefore, the damping force generated by the extension side damping valve 10 is made high damping force.

Next, when the vibration frequency is in the medium vibration frequency range of 3 to 8 Hz, it becomes difficult for the hydraulic oil to pass through the orifice 12a and the pilot upstream valve 12 is not opened. Extension side pressure chamber R
The oil pressure with the first-order lag will not be supplied to 1.

As a result, the backup force in the extension side damping valve 10 is eliminated, and the initial load in the extension side damping valve 10 is maintained at the initial setting,
Therefore, a low damping force is generated as compared with the above high damping force generation.

When the vibration frequency is in the high vibration frequency range of 9 hertz or higher, the pilot upstream valve 12
Even when the valve is still closed, the inertial force from the hydraulic oil acting on the pilot upstream valve 12 becomes large, so that the pilot upstream valve 12 is opened by the outer peripheral end bending.

As a result, the oil flow in the pilot passage, that is, the pilot flow toward the expansion side pressure chamber R1 is ensured, and the expansion side damping valve is the same as in the case of the low vibration frequency region described above. The back pressure acts on the back surface of the valve 10, so that the damping force generated by the extension side damping valve 10 becomes a high damping force.

When the vibration frequency is in the ultra-high vibration frequency range, the pilot upstream valve 12 due to the inertial force of oil
The opening and closing of the valve cannot follow the input due to its own response delay, and as a result, the backup force to the extension side damping valve 10 cannot be established, and the damping force generated by the extension side damping valve 10 gradually increases. Be lowered.

That is, according to the present invention, in the above-mentioned ultra-high vibration frequency range, the backup force for the extension side damping valve 10 is lost, and a reduction phenomenon of the damping force is caused.

Although the above description of the operation has been made by taking the case of the expansion side damping valve 10 as an example, the same operation as that described above is also realized in the compression side damping valve 20 and the pressure side pressure chamber R2. Of course.

[0064]

As described above, according to the present invention, the damping valve that enables the sprung mass damping at the sprung resonance point also enables the unsprung mass damping at the unsprung resonance point. It is possible to avoid in advance such a problem that a vibration frequency sensitive valve is provided for vibration suppression on the unsprung part and on the sprung part, so that the number of members does not increase unnecessarily.
There is an advantage that the general versatility of the shock absorber can be expected without increasing the total weight and the product cost of the shock absorber.

Further, according to the present invention, when a high damping force near the unsprung resonance point is generated by the low cut valve, the high damping force is still generated even after passing through the unsprung resonance point. There is also an advantage that the ride comfort of the vehicle is not deteriorated without causing such a problem.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a shock absorber according to the present invention partially broken away.

FIG. 2 is an enlarged partial vertical sectional view partially showing a main part of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 cylinder 3 piston part 10 expansion side damping valve as a damping valve 12 pilot upstream valve 12a orifice 17 pilot downstream valve 20 pressure side damping valve as a damping valve

Claims (1)

[Claims] 1. A damping valve provided in a piston part generates a predetermined damping force when the piston part slides in the cylinder, and a hydraulic pressure depending on a vibration frequency in the cylinder is applied to a pressure receiving surface of the damping valve. In a shock absorber formed so as to be able to change the opening area of the damping valve with respect to the upstream pressure by guiding it to the back side of the damping valve via a pilot flow path branched from the side and extending to the pilot flow path. A pilot upstream valve consisting of a leaf valve and a pilot downstream valve consisting of a leaf valve are arranged and formed so as to guide the hydraulic pressure between the pilot upstream valve and the pilot downstream valve to the back side of the damping valve. In addition, the shock absorber is characterized in that the pilot upstream valve is formed with an orifice for generating a first-order hydraulic pressure. Absorber