JPH0426751Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention relates to a hydraulic shock absorber, and in particular to a hydraulic shock absorber whose generated damping force is lowered or increased depending on its vibration frequency. Regarding improvements.

[Conventional technology]

Various types of hydraulic shock absorbers have been proposed in the past in which the damping force generated in the hydraulic shock absorbers is lowered or increased depending on the vibration frequency of the hydraulic shock absorbers.

For example, the applicant of the present application also proposed the following.

One of them is that when the vibration frequency exceeds a certain range, a so-called high-cut action is performed to reduce the high damping force that was previously generated and suppress the generation of damping force to a low level (as disclosed in Japanese Patent Application Laid-Open No. 61
-109933), and the other one generates a low damping force until the vibration frequency falls into a certain range, but when it exceeds the above range, a so-called low-cut action is performed that generates a high damping force. Yes (Special Application No. 161640, Showa 60).

In any of the above proposals, the free piston is lowered by the hydraulic pressure in the first-order lag pressure chamber that communicates with the cylinder oil chamber through one orifice, and the lower part is lowered by the lowering of the free piston. The bending rigidity of the peripheral end of the leaf valve is changed, thereby enabling the above-mentioned so-called high-cut action or low-cut action.

Therefore, even when the vibration frequency is in an extremely low range, if the diameter of the orifice that sets the oil pressure in the first-order lag pressure chamber is selected to be smaller, the desired value can be achieved based on the extremely low vibration frequency range. This means that either high-cut or low-cut action can be achieved.

[Problem that the invention attempts to solve]

However, it is a theoretical problem that if the orifice diameter is set smaller, the desired high-cut or low-cut action can be achieved based on an extremely low vibration frequency range; This causes the following inconveniences.

That is, first of all, it is extremely difficult to realize an extremely small orifice diameter, and even if it were achieved, precise work would be required and the productivity of the hydraulic shock absorber itself would be likely to be reduced. There is a certain inconvenience.

In addition, if the above-mentioned extremely small orifice diameter is used, the so-called clogging of the orifice due to sludge etc. is likely to occur when the hydraulic shock absorber is used, and when such clogging occurs, the value of the hydraulic shock absorber itself is reduced. There are inconveniences that will be lost.

Therefore, in view of the above-mentioned circumstances, the present invention enables a desired so-called high-cut action or low-cut action based on an extremely low vibration frequency range, without selecting an extremely small orifice diameter that would cause so-called clogging. The purpose is to provide a new hydraulic shock absorber.

[Means for solving problems]

In order to solve the above-mentioned problems, the configuration of the hydraulic shock absorber according to the present invention is made such that a damping force of a predetermined magnitude can be generated by bending the peripheral end of the leaf valve when the piston inside the cylinder slides. and a hydraulic shock absorber configured to reduce or increase the damping force of the predetermined magnitude by changing the amount of deflection of the peripheral end of the leaf valve by applying a pressing force from above to the leaf valve. In this case, the pushing force is obtained by lowering a push valve disposed on the upper surface of the leaf valve, and the push valve has a spring that supports at its upper end a spool that slides in the inner chamber of a pressure chamber that acts on the upper surface of the push valve. The lower ends are in contact with each other, and the pressure chamber is formed so as to communicate with the front chamber which communicates with the oil chamber in the cylinder through one orifice through another orifice. It is something.

[Effect]

Since the pressing force applied to the leaf valve from above is obtained by the hydraulic pressure in the pressure chamber that is generated through the two orifices, the timing for generating the specified hydraulic pressure in the pressure chamber is extremely low. It becomes possible to set it in the vibration frequency domain.

〔Example〕

Hereinafter, the present invention will be explained based on the illustrated embodiments.

As shown in FIG. 1, the hydraulic shock absorber according to the present invention has a piston rod 2 inserted into a cylinder 1.
It is assumed that the piston has a piston portion 3 at the lower end thereof, and a damping valve portion 4 is formed in the piston portion 3 to enable generation of a rebound damping force.

The inside of the cylinder 1 is divided into an upper oil chamber A and a lower oil chamber B by the piston part 3, and
An outer tube 10 is provided outside the cylinder 1, and a reservoir chamber C is defined between the cylinder 1 and the outer tube 10.

The lower oil chamber B and reservoir chamber C are as follows:
They communicate with each other via a base valve section 11 disposed inside the lower end of the cylinder 1.

The base valve section 11 is also provided with a pressure side valve 11a to enable generation of a desired pressure side damping force, and also provided with a check valve 11b and a relief valve 11c.

A bearing 12 is disposed at the upper end of the cylinder 1 and inside the upper end of the outer tube 10, and the piston rod 2 passes through the center of the bearing 12. is said to be able to slide freely.

Further, a seal 13 is interposed above the bearing 12, and the outer tube 1
A gas chamber D is located above the reservoir chamber C in the chamber 0.

Note that a mounting eye 14 is connected to the lower end of the cylinder 1, that is, the lower end of the outer tube 10.

Although not shown, the piston rod 2 is formed so that its upper end side can be connected to other parts, and in particular, in this embodiment, there is a vertical hole 2a inside from the lower end to the vicinity of the lower end. It has a side passage E consisting of a horizontal hole 2b, through which the upper oil chamber A can communicate with the lower oil chamber B.

The piston part 3 has a piston main body 30 interposed in the lower end spigot part 20 of the piston rod 2, and the piston main body 30 is attached to a piston nut 31 screwed into the lower end threaded part 21 of the piston rod 2. Therefore, it is fixed in a predetermined position.

The piston body 30 divides the inside of the cylinder 1 into an upper oil chamber A and a lower oil chamber B, and the piston body 30 has a port 30a at its lower end that opens into the lower oil chamber B. This allows communication between the upper oil chamber A and the lower oil chamber B.

A check valve 32 is adjacent to the upper end opening of the port 30a of the piston body 30,
In the check valve 32, the lower end of a non-return spring 34 whose upper end is engaged with a valve stopper 33 which is engaged with the stepped portion 22 of the piston rod 2 is brought into contact, and its outer peripheral end is urged downward. It is formed so that an initial load is applied.

Note that the valve stopper 33 is formed with a notch 33a through which oil can pass, and a piston ring 35 is interposed on the outer periphery of the piston body 30.

Therefore, the port 30a serves as a pressure-side oil passage through which oil in the lower oil chamber B flows to the upper oil chamber A during the pressure stroke in which the piston portion 3 descends within the cylinder 1.

The lower end of the side passage E formed in the piston rod 2 opens into an inner chamber 31a formed in the lower half of the piston nut 31.
A damping force valve section 4 is disposed within 1a.

In this embodiment, the damping valve section 4 has the following features:
As shown in FIG. 2, the annular leaf valve is used as a rebound damping force generating section and is located adjacent to the lower end opening of the port 40a of the block 40 disposed within the inner chamber 31a. 41, and the annular leaf valve 41 has a piston nut 3
A support point 42a of a disk 42 screwed inside the lower end of the disk 1 is supported so as to be in contact with the lower surface.

The support point 42a is positioned so as to come into contact with the inner lower surface of the upper annular leaf valve 41, and there is no surface on the outer upper end surface of the disk 42 having the support point 42a. , a ring seat 43 having the same wall thickness as the leaf valve 41;
is installed.

The annular seat 43 is provided in advance by attaching the leaf valve 41 to the upper end of the outer circumferential side of the disk 42, by omitting its arrangement.
It is also possible to form a protrusion having the same wall thickness as the disk, but if the ring seat 43 is provided as in this embodiment, the upper surface of the disk 42 can be easily finished, and the machining accuracy can be controlled. This has the advantage of making it easier.

The outer peripheral end of the annular leaf valve 41 is a free end, and the port 40 of the upper block 40
A, that is, the oil from the inner chamber 31a is allowed to flow into the lower oil chamber B through the port 42b of the lower disk 42 by bending the outer peripheral end of the leaf valve 41. A desired expansion damping force is generated when the outer peripheral end of the leaf valve 41 is bent.

The expansion-side damping force is made variable by applying a pressing force from above to the inner peripheral end of the annular leaf valve 41.

That is, a push valve 44 is in contact with the upper surface of the inner peripheral end of the annular leaf valve 41, a lower end of a spring 45 is in contact with the upper surface of the push valve 44, and a spool 46 is in contact with the upper end of the spring 45. is in contact.

The push valve 44, spring 45 and spool 46 are housed in the block 40, and a pressure chamber R is formed above the upper surface of the spool 46.

The pressure chamber R is defined by a check valve 47 arranged to close a central opening 40b at the upper end of the block 40.

An orifice 47a is bored in the center of the check valve 47, and the pressure chamber R communicates with the front chamber r formed above the orifice 47a through the orifice 47a. There is.

The front chamber r is formed in a downwardly concave shape on the lower surface of the center of the spacer 48 disposed on the upper surface of the check valve 47, and is arranged so as to close the central opening 48a at the upper end of the spacer 48. It is divided by a check valve 49 provided therein.

In the center of the check valve 49,
An orifice 49a is bored, and the front chamber r and the inner chamber 31 are connected through the orifice 49a.
It communicates with a.

Incidentally, in this embodiment, the check valves 47 and 49 that define the pressure chamber R and the front chamber r are identically formed.

That is, as shown in FIG. 3, each check valve 47, 49 is formed into a disk shape as a whole, and has orifices 47a, 49a in the center.

Each of the check valves 47 and 49 has cutout holes 47b and 49b in the circumferential direction on the outer circumferential side thereof, and the inner chamber 31a, the port 48b of the spacer 48, and the port 40 of the block 40.
Communication between a and a is possible.

In addition, the check valves 47, 49 have notch holes 47c, 49c in the circumferential direction on the inner peripheral side, and when the upper surface side of each check valve 47, 49 becomes negative pressure, each of the notch holes 47c , 49c, the hydraulic pressure in the pressure chamber R and the front chamber R is released to the upper surface side of each check valve 47, 49.

That is, in this embodiment, each check valve 4
7 and 49 each have a spring action.

Therefore, when the piston part 3 moves upward in the cylinder 1 and the hydraulic pressure in the upper oil chamber A becomes high, the high pressure reaches the inside of the inner chamber 31a via the side passage E. , the orifice 49 of the check valve 49 where the internal pressure in the internal chamber 31a is above
The pressure is reduced through a and extends into the front chamber r.

Then, the internal pressure in the front chamber r is further reduced through the orifice 47a of the check valve 47 below and reaches the pressure chamber R.

As a result, the pressure chamber R acts as a pressure reduction chamber, and this reduced hydraulic pressure acts as a pressing force on the push valve 44 via the spool 46 and spring 45, and the lower annular leaf valve 41. The inner peripheral end is pressed downward.

Then, due to the pressing force applied to the inner peripheral end from above, the upper surface of the outer peripheral end of the leaf valve 41 is urged to be pressed against the lower surface of the upper block 40, that is, the leaf valve 41 The deflection characteristics of the outer peripheral edge of the material will be changed.

The operation of the hydraulic shock absorber according to the present invention formed as described above will be briefly explained.

During the extension stroke in which the piston part 3 moves up inside the cylinder 1, the upper oil chamber A becomes a high pressure side, and the oil in the upper oil chamber A flows into the piston nut 31 through the side passage E in the piston rod 2. It flows into the chamber 31a.

A part of the oil that has flowed into the inner chamber 31a flows through the orifice 49 of the upper check valve 49.
At the same time, other oil flows into the port 48a of the lower spacer 48 through the notch hole 49b on the outer circumferential side of the upper check valve 49, and the other oil flows into the port 48a of the lower spacer 48. The oil flowing into the check valve 48a flows into the lower block 4 through the cutout hole 47b on the outer peripheral side of the lower check valve 47.
0 into the port 40a, and the corresponding port 40a
The oil flowing inside bends the outer peripheral end of the leaf valve 40 and flows into the lower oil chamber B.

When the outer circumferential end of the leaf valve 41 is bent to induce oil flow, a predetermined extension-side damping force is generated.

At this time, if the vibration frequency in the upper oil chamber A in the cylinder is in an extremely low range, the oil is allowed to flow through the upper orifice 49a and the lower orifice 47a, and the pressure A reduced internal pressure will be generated within the chamber R.

Then, due to the generation of the internal pressure, the spool 4
6 descends within the block 40, and the spool 46
The lowering of the lower push valve 44 via the spring 45 causes the lower push valve 44 to be lowered.

The lowering of the push valve 44 presses the inner peripheral end of the leaf valve 41 downward, so that the upper surface of the outer peripheral end of the leaf valve 41 is pressed against the lower end surface of the outer peripheral side of the upper block 40. Become.

That is, in contrast to the situation where the outer circumferential end of the leaf valve 41 is deflected and deformed by the above-mentioned oil flow to enable generation of a predetermined rebound damping force, the deflection characteristics of the outer circumferential end of the leaf valve 41 are will be changed.

Therefore, when the vibration frequency in the upper oil chamber A in the cylinder is in an extremely low range, internal pressure is generated in the pressure chamber R, which changes the outer circumferential end deflection characteristics of the leaf valve 41, resulting in a high expansion side. This means that damping force can be generated.

When the vibration frequency in the upper oil chamber A in the cylinder moves to a high range, oil flow no longer occurs through the orifices 47a and 49a, and no internal pressure is generated in the pressure chamber R. As a result, the outer circumferential end deflection characteristic of the leaf valve 41 is returned to its original state, and from then on, a high damping force is no longer generated, that is, a so-called high-cut effect is exerted in which the generation of a low damping force is suppressed.

In addition, during the pressure side stroke in which the piston part 3 descends within the cylinder 1, the check valve 32 of the piston part 3 is opened and oil from the lower oil chamber B is sucked into the upper oil chamber A, and the piston rod 2
An amount of oil corresponding to the intrusion volume flows into the reservoir chamber C via the pressure side valve 11b of the base valve section 11.

Furthermore, during the aforementioned extension stroke, an amount of oil corresponding to the volume of the piston rod 2 that is insufficient in the lower oil chamber B is replenished from the reservoir chamber C.

FIG. 4 shows a piston part 3 and a damping valve part 4 connected to the piston part 3 according to another embodiment of the present invention, in which the piston part 3 is attached to the piston rod 2 in the same manner as in the above-mentioned embodiment. It is fixed to the lower end by a piston nut 31, and the piston nut 3
The damping valve section 4 is provided in the inner chamber 31a of the first embodiment.

The damping valve section 4 is used as a damping force generating section on the expansion side, as in the case of the above-mentioned embodiment, but in this embodiment, contrary to the so-called high-cut action, the damping force is generated in an extremely low frequency region. Within this range, a low damping force is generated, but when the above range is exceeded, a high damping force is generated, which is a so-called low-cut effect.

Hereinafter, the differences between this embodiment and the above-described embodiments will be mainly explained.

First, the piston rod 2, which has a piston portion 3 at its lower end that divides the inside of the cylinder 10 into an upper oil chamber A and a lower oil chamber B, is provided with a side passage E (see FIG. 1) as in the above embodiment. I don't have it, but
The piston body 30 forming the piston part 3 includes
In addition to port 30a on the outer circumference side, port 3 on the inner circumference side
0b, and the upper oil chamber A and the lower oil chamber B
It is now possible to communicate with

The check valve 32 adjacent to the upper end openings of the ports 30a, 30b has a notch 32a at a portion opposite to the upper end opening of the inner ports 30b.
The oil in the upper oil chamber A is connected to the port 30b.
It is now possible for it to flow inside.

Further, the lower end opening of the inner port 30b is connected to a port 30 formed at the upper end side of the piston nut 31.
It faces the upper end opening of b.

Next, the leaf valve 4 in the damping valve section 4
1 is formed in a disk shape instead of being formed in an annular shape as in the above-described embodiment (see FIG. 2), and has a support point 42 on the upper surface of the lower disk 42.
a is in contact with the lower surface of the leaf valve 41 closer to the inner periphery, and the pressing point 44a of the upper push valve 44 is on the upper surface of the inner periphery of the leaf valve 41, and is located on the outer periphery of the contact area of the support point 42a. It abuts at a position near the edge.

Therefore, when a downward pressing force is applied to the pressing point 44a of the push valve 44,
The outer circumferential end of the leaf valve 41 will be deflected to a greater extent than the set deflection amount.

The pressure chamber R that applies a pressing force to the push valve 44 is located at the orifice 47 of the check valve 47.
a, and the front chamber r communicates with the inner chamber 31a through an orifice 49a of the check valve 49, but the check valves 47, 49 and the spacer forming the front chamber r 4
8. Furthermore, a non-return spring 50 that energizes these is housed in a valve case 51 adjacent to the upper end of the block 40.

The inside of the valve case 51 communicates with the inner chamber 31a through an opening 51a at the center of the upper end, and the port 40a of the block 40 communicates with the inner chamber 31a through a port 51b on the outer peripheral side of the valve case 51. It is communicated.

In this embodiment, the disk 42 is fixed to the inner periphery of the lower end of the piston nut 31 by caulking.

Further, it is assumed that the upper and lower check valves 37, 39 and the intermediate spacer 38 are energized by the upper non-return spring 50, but that no spring effect is imparted to each check valve 37, 39.

Therefore, in the embodiment described above, each check valve 37, 39 is formed with a thin wall to provide a spring effect, and therefore it is expected that the oil pressure in the so-called upstream oil chamber will be extremely high. In contrast to the above-mentioned embodiments, which are not preferred, this embodiment has the advantage that it can be used even when the upstream oil chamber is under high pressure.

[Effect of idea]

As described above, according to the present invention, the hydraulic pressure generated in the pressure chamber is set via the double orifice. This means that the same effects as those obtained when generating an orifice can be obtained, eliminating the need for forming an extremely small orifice diameter, and eliminating the risk of clogging that can occur when using an extremely small orifice diameter. There are advantages to being able to do so.

As a result, the productivity of the hydraulic shock absorber itself is improved, and the reliability of use of the hydraulic shock absorber is improved.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway vertical sectional view of a hydraulic shock absorber according to an embodiment of the present invention; FIG. 2 is an enlarged longitudinal sectional view of a piston portion and a damping valve portion in FIG. 1; FIG. 3 is a plan view showing a check valve in the damping valve section, and FIG. 4 is a view similar to FIG. 1 showing a hydraulic shock absorber according to another embodiment of the present invention. 1...Cylinder, 2...Piston rod, 3...
...Piston part, 4...Dampening valve part, 31...Piston nut, 41...Leaf valve, 44...
Push valve, 45...Spring, 46...
Spool, 47a, 49a... Orifice, A...
...Upper oil chamber, B...Lower oil chamber, R...Pressure chamber, r
……Front chamber.

Claims (1)

[Claims for Utility Model Registration] (1) A damping force of a predetermined magnitude can be generated by bending the peripheral end of the leaf valve when the piston inside the cylinder slides, and an upward force applied to the leaf valve can be generated. In a hydraulic shock absorber formed in such a way that the damping force of the predetermined magnitude can be reduced or increased by changing the amount of deflection of the circumferential end of the leaf valve with a pushing force from above, the pushing force is applied to the upper surface of the leaf valve. is obtained by lowering a push valve disposed in the push valve, and the push valve is brought into contact with the lower end of a spring whose upper end supports a spool that slides due to the internal pressure of the pressure chamber acting on the upper surface of the push valve, and A hydraulic shock absorber characterized in that the pressure chamber is formed so as to communicate with a front chamber which communicates with the oil chamber in the cylinder through one orifice through another orifice. (2) The hydraulic shock absorber according to claim 1, wherein the leaf valve is disposed within a piston nut that fixes a piston portion to the lower end of a piston rod inserted into a cylinder. (3) The hydraulic shock absorber according to claim 1, wherein the leaf valve is formed in an annular or disc shape.