JPS5865340A - Oil hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To always efficiently absorb fine vibration of high frequnecy, by providing a damping chamber in the lower part of a base valve, housing a sub- piston in the damping chamber and communicating a lower chamber of the sub- piston to the damping chamber and reservoir chamber. CONSTITUTION:A slidable sub-piston 24 is housed in a casing 23, provided between a body 19 and plug unit 25 of a base valve 16, and an internal part of the casing 23 is partitioned to a damping chamber D, communicated to a lower oil chamber C, and a lower chamber E of the sub-piston 24, while the damping chamber D and the lower chamber E are communicated through an orifice 27 formed in the sub-piston 24. Then the lower chamber E is communicated to a reservoir chamber A by passages F1 and F2. A piston speed is increased, if communication of the lower oil chamber C to the reservoir chamber A is shut off, working oil in the lower oil chamber C opens a damping valve 21, interposed in an oil passage 20, to flow as shown by arrow heads of broken lines, and relatively high prescribed damping force can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a hydraulic shock absorber for a vehicle that has a shock absorbing performance that satisfies both the characteristics of the original specified damping force range when the piston speed is above a predetermined value and the low damping force range when the piston speed is very small. Regarding the improvement of hydraulic shock absorbers with conventional hydraulic shock absorbers of this type, for example, there is a hydraulic shock absorber as shown in FIG.
80541, etc.).

This is provided with a chamber below the pace pulp (check pulp) 2 provided at the bottom of the cylinder 1, which communicates with the lower oil chamber C of the cylinder 1 through an orifice 3, and a spring 4 inside the chamber. A sub-piston 5 is provided which is always urged in a direction to contract the volume of the chamber, and a lower chamber E of this sub-piston 5 is configured to communicate with the reservoir chamber A via passages Fl and F2.

According to this, in the compression stroke, the hydraulic oil in the lower oil chamber C first flows into the chamber above the sub-piston 5 through the orifice 3, and moves the sub-piston 5 downward against the spring 4, while As a result, the oil in the lower chamber E of the sub-piston 5 escapes to the reservoir chamber A via the passages Fl and F2.

Therefore, the volume of the chamber increases by the amount of descent of the piston 5, and this increased amount of hydraulic fluid escapes into the chamber, and the resistance caused by the orifice 3 at this time generates a damping force in a region where the piston speed is low. Therefore, hydraulic damping is performed at the beginning of the piston stroke and in the minute stroke range, thereby suppressing the transmission of high-frequency minute vibrations to the vehicle body due to minute irregularities on the road surface.

On the other hand, when the piston stroke becomes large, the sub-piston 5 eventually closes the passage F1 with its skirt portion 5A, and the inside of the lower chamber E becomes oil-locked.

As a result, when the pressure inside the lower oil chamber C reaches the set pressure of the pace pulp (check pulp) 2 and it opens, the hydraulic oil flows through the pace pulp 2 to the reso-pa chamber A, and the operation is stabilized. to obtain the required damping force.

In this way, both the low damping force range in the small stroke range at the beginning of the piston stroke and the original specified damping force range are achieved, improving ride comfort and handling, especially in high-speed driving ranges. It's getting older.

However, in such conventional hydraulic shock absorbers,
When the piston stroke becomes large to a certain extent regardless of its speed, the lower chamber E of the sub-piston 5 becomes oil-locked, so when driving at high speed on a good road with gentle undulations, low-frequency vibrations can occur. When high-frequency micro vibrations are combined, as mentioned above, the secondary piston 5 bottoms out according to the piston stroke 2 and the volume of the chamber above the secondary piston 5 remains unchanged. There was a problem that it could not absorb the minute vibrations of .

Therefore, this invention stores a pressurized secondary piston in a buffer chamber that communicates with the lower oil chamber of a cylinder provided at the lower part of the pace pulp, and also inserts the compressed secondary piston into the buffer chamber through an orifice formed in the secondary piston. By communicating the lower chamber of the sub-piston with the lower chamber of the sub-piston, and communicating the royal part of the sub-piston with the reservoir chamber, high-frequency micro-vibration can always be efficiently absorbed regardless of the stroke position of the piston. The purpose is to

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

As shown in FIG. 2, the hydraulic shock absorber lO includes an inner cylinder 11 forming a cylinder and an outer cylinder 1 disposed outside the inner cylinder 11.
A main piston 13 for generating damping force is slidably fitted into the cylinder 11, a piston rod 14 projects above the cylinder 11 and is connected to the vehicle body, and a lower part of the outer cylinder 12 is connected to the wheel side.

The piston 13 is provided with pulp, an orifice, etc., and a pace pulp 16 is provided on the bottom of the inner and outer cylinders 11 and 12, and a pace pulp 16 is provided on the body 15, and the upper ends of the inner and outer cylinders 11 and 12 are They are concentrically connected by a front guide 17. In the figure, 18 is an oil seal.

Among the above, the outer cylinder 11 and 12 are provided with a beam data tZ chamber, and the inside of the cylinder 11 is partitioned by a piston 13, and lower oil chambers B and C are formed, and the oil chambers B and C are filled with hydraulic oil. is full of. A suspension spring (not shown) is interposed between the upper end of the piston rod 17 and the bottoms of the inner and outer cylinders 11 and 12.

The pace pulp 16 is provided at the bottom of the cylinder 11, as shown in FIG. The oil passage 20 is provided with a damping pulp 21 that opens the kernel oil passage 20 at 9:00 when the piston speed during the compression stroke is blocked and the hydraulic oil in the lower oil chamber C rises to a predetermined value. Similarly, a damping pulp 22 is provided which opens during the extension stroke.

Since the structure and function of these pulps 21 and 22 are known, their explanation will be omitted. .

A cylindrical casing (piston nut) 23 is provided in the axial direction between the body 19 and the plug 15, and the casing 23 is moved by a susol-like sub-piston 24 that is slidably housed in the casing 23. A buffer chamber communicating with the lower oil chamber C via a passage 26 formed in the center core 25 to which the casing 23 of the valve body 19 is screwed, and an orifice 27 formed in the sub-piston 24 in this buffer chamber. The sub-piston 240 communicates with the lower chamber E through the sub-piston 240.

The lower chamber E of the auxiliary piston 24 is integrated into a passage F1 and a diode 19 formed in the casing 23, and communicates with the reservoir chamber A through a water passage F2 as required.

That is, normally, the secondary piston 24 is urged upward in the figure by the spring 28 whose base end is supported on the bottom wall -23A of the casing 23, so that the passage F1
is opened, and the lower chamber E of the sub-piston 24 becomes the reservoir chamber All+.
Conversely, the outer peripheral portion 24B of the sub-piston 24 closes the passage F1, thereby blocking the sub-piston 240 lower-E from the reservoir chamber A side.

Because of this structure, in the low piston speed range during the compression stroke of the piston 13, the hydraulic oil in the lower oil chamber C is slowly flowing as shown by the solid line arrow in FIG. D to the lower chamber E of the sub-piston 24 via the orifice 27 of the sub-piston 24, and from there via the passages F1 and F3.
- Outflows into chamber A.

At this time, if the above-mentioned orifice is not installed, the opening area of the key 7 is such that the working pressure of the lower oil chamber C is
In order not to overcome the force, that is, the secondary piston 24
is set in advance to a predetermined value so that it does not move down to the position where it closes the passage Fl, so in the low speed range, the lower oil chamber C is always connected to the pressure chamber A side via the orifice 27 regardless of the piston stroke. communicate.

As a result, a low damping force characteristic determined by the orifice 27 is obtained in the low piston speed range, as shown in characteristic 0) in the figure. It can effectively absorb and attenuate even minute irregularities on the road surface, and suppress transmission of high-frequency minute vibrations to the vehicle body. -1-\,
' On the other hand, as the piston speed increases, the above-mentioned pressure difference between the front and rear of the orifice overcomes the force of the megging ring 28 and moves downward, and the outer peripheral part of the piston is moved downward at the position where the lower end part 24A of the piston comes into contact with the stopper 15 as mentioned above. 24B closes the passage F1 and blocks communication between the lower oil chamber C and the reservoir chamber A.

Therefore, above the piston speed at this time, the above-mentioned hydraulic oil flow path system is always shut off, and after that, the hydraulic oil in the lower oil chamber C, whose pressure increases according to the piston speed, flows into the oil passage 2o as indicated by the broken line arrow. When the interposed damping pulp 21 is opened and allowed to flow, the damping force characteristics at this time are determined by the pulp 21, and the damping force rapidly rises to the normal damping force (
Characteristics of the 4th MJ (a) Reference R).

As a result, a relatively high predetermined damping force is obtained in the high piston speed range, thereby maintaining good steering stability.

As explained above, according to the present invention, the compressed sub-piston is housed in the buffer chamber communicating with the lower oil chamber of the cylinder provided at the lower part of the base pulp. The buffer chamber and the lower chamber of the auxiliary piston communicate with each other, and the lower chamber of the auxiliary piston communicates with the reservoir chamber through a passage, so that damping is low in the low piston speed range regardless of the piston stroke. It is possible to maintain force characteristics, reliably absorb high-frequency micro-vibrations from the road surface, and improve riding comfort, while also exerting a predetermined high damping force in the piston high-speed range.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main part of the conventional example, FIG. 2 is a sectional view showing the entire embodiment of the present invention, FIG. 3 is a sectional view of the main part, and FIG.
(2) is also a comparative explanatory diagram of damping force characteristics. 11... Cylinder (inner cylinder), 13... Piston, A
...Reso-p<M,,, 16-Base pulp, 21
...Check pulp, 1o...Hydraulic shock absorber, C...
・Lower oil chamber, D...buffer chamber, 28...sgeling,
24... Sub-piston, 27... Orifice, E...
・Lower chamber of sub-piston, Fl, Fx...passage.
' Patent applicant Senba Kogyo Co., Ltd. Figure 1 Figure 2 Figure 3 214- Figure 4

Claims (1)

[Claims] In a hydraulic shock absorber equipped with a piston that slides in a cylinder filled with hydraulic oil, and a pace pulp at the bottom of the cylinder that opens in the specified damping force range of the piston compression stroke and allows the hydraulic oil to flow out into the reservoir/chamber 9.・A buffer chamber is provided at the bottom of the pace pulp that communicates with the lower oil chamber of the cylinder, and a pressurized secondary piston is housed in this buffer chamber, and the connection between the buffer chamber and the secondary piston is established through an orifice formed in the secondary piston. A hydraulic shock absorber characterized in that the lower chamber of the auxiliary piston is communicated with the reservoir chamber through a passage.