JPH0137245Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a damping force generating device for a shock absorber, and more particularly to a damping force generating device suitable for use in a strut-type shock absorber for vehicles, particularly four-wheeled vehicles.

As a damping force generating device for a strut-type shock absorber suspended between a vehicle body and an axle of a four-wheeled vehicle, for example, one having a valve structure as shown in FIG. 1 is known.

In the shock absorber shown in FIG. 1, a piston rod 3 is slidably inserted into a cylinder 1 via a piston 2, and the piston 2 partitions two liquid chambers 4 and 5 into the cylinder 1. , 5 communicate with each other through through holes 6 and 7 provided in the piston 2.

A leaf valve 8 is provided at the upper end of one of the through holes 6 so as to be openable and closable, and a main leaf valve 9 is provided at the lower end of the other through hole so as to be openable and closable. The leaf valve 9 is biased in the closing direction by a spring 11 interposed between the leaf valve 10 and the leaf valve 9, and the other leaf valve 9 is biased in the closing direction via a spring 12 and a spring seat 13.

On the other hand, a valve case 2a of a base valve is held in the lower part of the cylinder 1, and through holes 6a and 7a are formed in the valve case 2a to communicate the liquid chambers 5 and 5a, and a leaf valve 8a is formed at the upper mouth end of the through hole 6a.
A leaf valve 9a is provided at the lower end of the other through hole 7a so as to be openable and closable. The leaf valve 8a is placed on a protrusion 14', in which a stamped orifice 14a is formed.

The damping force of the extension stroke in the above-mentioned shock absorber is generated by the resistance when the piston rod 3 and piston 2 move to the left in the figure and the hydraulic oil flows out from the liquid chamber 4 to the liquid chamber 5 through the valve and the through hole. . in general
At a piston speed of around 0.1 m/s, a damping force is generated due to fluid resistance when passing through the orifice 14a carved into the upper surface protrusion 14 of the piston 2, and at a speed of around 0.3 m/s, damping force is generated by the force of the spring 12 against the leaf valve 9. Damping force is generated by the fluid resistance that overcomes the set load and pushes it open, and also by the fluid resistance when passing through the through hole 7 at a speed of 0.6 m/s or more.

Similarly, in the compression stroke, the stamped orifice 14a' of the base valve produces a damping force of around 0.1 m/s, and the rigidity of the leaf valve 9a produces a damping force of around 0.3 m/s.
A damping force of around 0.6 m/s or more is generated in the through hole 7a.

As mentioned above, the damping force in the low speed range of around 0.1 m/s is generated by the fluid resistance when passing through the stamping orifices 14a and 14a'.
a and 14a' are narrow in width (approximately 2 mm) and shallow in depth (0.15 mm), so even if three of them are formed, the total area is small and is easily affected by the viscosity of the oil. This is especially true at low temperatures, and when the temperature drops to about -30°C, the fluid resistance increases significantly, for example, by about 3 to 8 times.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a damping force generating device for a shock absorber that reduces the influence of increased viscosity of oil in a low temperature environment.

In order to achieve the above object, the present invention arranges a sub-leaf valve and a main leaf valve in series at the end of one of the liquid chambers of a through hole that communicates two liquid chambers, and also A bypass port communicating with one of the liquid chambers is opened on the downstream side, and the hydraulic oil discharged from the other liquid chamber by opening a sub-leaf valve flows out into one liquid chamber via the bypass port in a low speed region. , the main leaf valve is opened at medium speed range or above, and the liquid flows out to one of the chambers.

The embodiment of the present invention will be described below with reference to FIG. 2 and subsequent figures.

FIG. 2 shows a half-sectional view of a shock absorber damping force generating device according to a preferred embodiment of the present invention.

That is, the piston rod 3 is slidably inserted into the cylinder 1 via the piston 2, and the piston rod 3 is slidably inserted into the cylinder 1 via the piston 2.
The inside of the cylinder 1 is divided into two liquid chambers 4 and 5 on the left and right.

A plurality of through holes 6, 7 are bored in the piston 2 in the axial direction, and these through holes 6, 7 communicate the two liquid chambers 4, 5.

An annular projection 14 is provided on the upper left side of the piston 2.
is formed, and an opening 8 is formed in the center on this protrusion 14.
A leaf valve 8, which is a non-return valve, is mounted to open and close one of the through holes 6.

A valve holder 10 is held on the piston rod 3, and a spring 11 is interposed between the valve holder 10 and the leaf valve 8.
When the leaf valve 8 is at rest, it is energized in the direction of closing the through hole 6.

On the lower right side of the piston 2, an annular projection 15 with a high seating height stands up inside the opening end of the through hole 6, and an annular projection 15 with a low seating height stands at the lower opening end of the other through hole 7.
6 stands up, and the sitting height of one of these projections 15, 16 is higher and protrudes downward by that height.

On the annular protrusion 16 on the side of the through hole 7, the outer peripheral seat part of a sub-leaf valve 17 is placed so as to be openable and closable, and on the other annular protrusion 15, the main leaf valve 9 is placed so as to be openable and closable. The proximal ends of 9 and 17 are stacked with a spacer interposed therebetween. However, between the base end seat surface of the sub-leaf valve 17 and the seat surface of the outer peripheral seat portion, the outer peripheral seat surface is higher.

Each leaf valve 9, 17 and spacer are held between the upper end of a cylindrical spring seat 18 whose base end is screwed into the piston rod 3 and the lower end surface of the piston 2. The spacer forms a gap between the sub-leaf valve 17 and the main leaf valve 9, and regulates the amount of deflection of the sub-leaf valve 17 by its thickness.

Main leaf valve 9 has spring seat 18
Spring 12 interposed between the flange part of
It is biased in a direction to close the through hole 7 via a spring seat 13 having an L-shaped cross section.

Furthermore, a diagonal bypass port 19 is formed in the piston 2, and one end of this port 19 is connected to the through hole 6.
The other end is opened between the protrusions 15 and 16, in other words, between the sub-leaf valve 17 and the main leaf valve 9 on the downstream side of the sub-leaf valve 17.

Although the structure of FIG. 2 is illustrated so that a damping force is generated during an extension operation, it can also be used as a damping force generating device during a compression operation, for example, when it is incorporated into a base valve. That is, in this case, the same mechanisms as the bypass port 19 and sub-leaf valve 17 shown in FIG. 2 are incorporated into the same valve case as shown in FIG. 1. Therefore, it is applicable to both stretching and compression, but since the operation is the same, the operation during stretching will be described below.

When the piston rod 3 extends to the left in the figure, the hydraulic oil in the upper liquid chamber 4 passes through the valve holder 10, the non-return spring 11, the opening 8a of the leaf valve 8, and the through hole 7 to the subleaf that controls the low-speed damping force. The valve 17 is pushed open and the water flows out to the upper surface side of the main leaf valve 9. At this time, the main leaf valve 9 still does not open due to the load of the spring 12, and the hydraulic oil flowing out from the sub-leaf valve 17 passes through the bypass port 19 and the through hole 6 to the lower liquid chamber 5.
leaks into The through holes 6, 7 and the port 19 are sized so as to cause almost no fluid resistance against flow rates in a low speed range. The amount of oil in the liquid chamber 5 corresponding to the volume of the piston rod coming out is the cylinder 1.
It is supplied from a reservoir below the outer periphery via a base valve.

By the way, when the outer peripheral seat part that contacts the protrusion 16 of the sub-leaf valve 17 is pushed open and the hydraulic oil flows out, the differential pressure between the upstream and downstream sides of the sub-leaf valve 17 is determined by the rigidity of the sub-leaf valve 17. . In other words, by changing the plate thickness of the sub-leaf valve 17, the damping force in the low speed range can be controlled. Regarding the inner and outer seat surfaces of the sub-leaf valve 17, as described above, the outer circumferential seat surface is made higher downward than the base end seat surface to control the pressing force against the outer circumferential seat surface. Due to the height difference in the seat surface and the rigidity of the sub-leaf valve 17 itself,
The differential pressure between the upstream and downstream sides is almost fixed and is not easily affected by the viscosity of the hydraulic oil. That is, when the viscosity of the hydraulic oil increases and the differential pressure across the sub-leaf valve 17 increases, the deflection of the sub-leaf valve 17 increases, increasing the opening area and balancing the differential pressure with the rigidity of the sub-leaf valve 17. When the viscosity decreases and the differential pressure decreases, the deflection of the sub-leaf valve 17 decreases, reducing the opening area and preventing the differential pressure from decreasing. By adopting this structure, it is possible to reduce the increase and decrease in differential pressure, that is, damping force, due to temperature changes.

The bypass port 19 is a communication hole determined by the damping force in the low to medium speed range, and is made larger when the damping force value is small, and smaller when the damping force value is large. This bypass port 19 is a choke hole in fluid mechanics and is affected by viscosity, so it is preferable to have a cross-sectional area that is at least larger than the area equivalent to a conventional orifice punch.

The piston speed increases and the subleaf valve 17
When the differential pressure before and after overcomes the set load of the spring 12 and the rigidity of the main leaf valve 9 itself,
The outer peripheral seat portion of the main leaf valve 9 opens,
Controls the damping force in the medium speed range.

Further, the damping force in the high-speed range of, for example, around 0.6 m/s or more is controlled by the fluid resistance passing through the through hole 7. That is, in a speed range where changes in damping force due to temperature changes (temperature characteristics) are small, the operation is the same as in the conventional case shown in FIG.

The main leaf valve 9 has a single plate valve biased in the closing direction by a spring 12 in FIG. The plurality of plate valves may be stacked on top of the sub-leaf valve 17 with a spacer interposed therebetween, and the damping force may be produced by utilizing the rigidity of the plurality of plate valves themselves.
If a so-called notch leaf valve is used, which has a notch passage on the outer circumference of the innermost leaf valve that contacts the protrusion 15 that is the seat surface of a plurality of plate valves,
Since the cutout passage serves as a bypass passage, the bypass passage can be eliminated. This also applies to other embodiments described below.

Next, FIG. 3 shows another embodiment of the present invention, in which the bypass port 19 of FIG. 2 is modified, and all other configurations are the same as the damping force generating mechanism of FIG. 2. That is, one or more bypass ports 19a are bored in parallel with the through holes 6 and 7 in the axial direction of the piston 2, and the upper opening end of the bypass port 19a is inserted through the upper surface of the piston 2. It is opened on the same plane as the mouth end of the hole 6, and the lower mouth end is opened downstream of the sub-leaf valve 17. Therefore, in the low to medium speed range, the hydraulic oil that flows out by deflecting the sub-leaf valve 17 is introduced into the lower liquid chamber 5 through the bypass port 19a, the liquid chamber on the upper side of the piston 2, and the through hole 6. . It goes without saying that the sub-leaf valve 17 and the bypass port 19a can be provided in the valve case of the base valve to generate compression-side damping force.

Next, FIG. 4 shows another embodiment of the present invention. In the embodiments shown in FIGS. 2 and 3, the bypass ports 19 and 19a are provided in the body of the piston 2, but in the embodiment shown in FIG. A bypass port 20 with a notch that is not easily affected is formed in the radial direction. This bypass port 20 is the second
If configured to have an area equivalent to the bypass ports 19, 19a in FIGS. It is. This configuration facilitates machining, and the operation is performed by the second
It is the same as that in Fig. 3. All other structures are the same as in the case of FIG. It is also possible to adopt this configuration to a base valve.

As described above, the present invention provides a sub-leaf valve and a main leaf valve that can be opened and closed freely at the mouth end of a through hole that communicates two liquid chambers, and a bypass port is formed downstream of the sub-leaf valve, and a bypass port is formed downstream of the sub-leaf valve. In this case, the hydraulic oil discharged from one liquid chamber against the rigidity of the sub-leaf valve flows into the other liquid chamber via the bypass port.In other words, the rigidity of the leaf valve is utilized. Since the damping force is generated by controlling the pressure difference between the upper and lower working chambers, the influence of increased viscosity in a low-temperature environment can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a half-sectional view of a damping force generating device for a conventional shock absorber, FIG. 2 is a half-sectional view of a damping force generating device for a shock absorber according to an embodiment of the present invention, FIGS. 3 and 4, FIG. 2 is a half-sectional view of a shock absorber damping force generating device according to another embodiment. 2...Piston, 2a...Valve case, 4,
5, 5a...Liquid chamber, 9...Main leaf valve,
13... Spring seat, 15... Annular projection,
17...Sub leaf valve, 19, 19a, 20
...Bypassport.

Claims (1)

[Claims for Utility Model Registration] (1) A subreamer valve and a main leaf valve are sequentially arranged in series at the end of one of the liquid chambers of a through hole that communicates two liquid chambers, and the subleaf valve is A bypass port communicating with one of the liquid chambers is opened on the downstream side, and the hydraulic oil discharged from the other liquid chamber by opening a sub-leaf valve flows out into one liquid chamber via the bypass port in a low speed region. , a shock absorber damping force generator that opens the main leaf valve to allow liquid to flow out to one chamber at medium speeds or above. (2) The damping force generating device for a shock absorber according to claim 1, wherein a through hole is provided in the piston. (3) The damping force generating device for a shock absorber according to claim 1, wherein the through hole is provided in the valve case. (4) Scope of utility model registration claim No. 1 where the bypass port is provided in the piston or valve case
A damping force generating device for a shock absorber as described in 2. (5) A damping force generating device for a shock absorber according to claim 1 of the utility model registration, in which a bypass port is provided on an annular protrusion that holds a main leaf valve.