JPS5916131B2 - hydraulic shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hydraulic shock absorber installed on two-wheeled vehicles, four-wheeled vehicles, etc., and more specifically, an inner tube connected to the vehicle body side can be freely slid into an outer tube connected to the wheel side. This invention relates to a hydraulic shock absorber inserted into a hydraulic shock absorber.

Conventionally, this type of hydraulic shock absorber has an inner tube 2 slidably inserted into an outer tube 1, as shown in FIG.
A hollow pipe 3 is protruded inward, and at the tip of the hollow pipe 3 there is an auxiliary piston 4 that slides into the inner tube 2, and below the inner tube 2 there is a piston 5 that slides into the hollow pipe 3. The outer tube 1, inner tube 2, hollow pipe 3, auxiliary piston 4, and piston 5 form a chamber A and a chamber B that generate a damping force when the hydraulic shock absorber is extended.

In the compression operation in which the inner tube 2 descends against the spring 6, a check valve 5 disposed on the piston 5
Oil is sucked from chamber B into chamber A through a, and at the same time oil is discharged into the oil reservoir chamber C through the hollow pipe 3 through the through hole 7 in an amount corresponding to the volume of the inner tube 2 entering the chamber B.

In addition, in the extension operation in which the inner tube 2 rises, a damping force is generated by discharging the oil in the chamber A into the hollow pipe 3 through the orifice 8, and at the same time, a damping force is generated due to the insufficient volume of the inner tube 2 in the chamber B. The amount of oil is compensated from the oil reservoir chamber C through the hollow pipe 3 and the through hole 7.

Furthermore, when the inner tube 2 is at its maximum extension, the piston 5 passes through the orifice 8 to put the chamber A in a hydraulically locked state to reduce the impact, and even at its maximum compression, the hollow body 9 at the lower end of the inner tube 2 is closed to the oil hole. By fitting into the rod 10, the chamber B is placed in a hydraulically locked state, thereby mitigating the impact.

In the hydraulic shock absorber configured in this way, the flow rate of oil from the hollow pipe 3 to the oil reservoir chamber C during compression operation is extremely high, causing the oil to blow up into the air chamber above the oil reservoir chamber C or cause the oil to flow into the oil reservoir chamber C. Room C
Air is drawn into the oil surface and the oil and air mix due to the internal stirring action.

As a result of the oil mixed with air flowing into chambers A and B during expansion, the resistance passing through the orifice 80 decreases, making it impossible to obtain the desired damping force, or compressing the air on the oil surface, causing the hydraulic shock absorber to It had drawbacks such as a decrease in impact mitigation ability at the time of maximum expansion and contraction.

The present invention focuses on the fact that the above-mentioned drawback is caused by compensating for the oil amount change in the oil sump chamber C due to the large protrusion of the inner tube. The embodiment shown in FIGS. 1 to 3 will be described below.

In the main body, an inner tube 2 is slidably inserted into an outer tube 1 as in the conventional case, and a hollow pipe 3 is provided protruding from the bottom of the outer tube 1 into the inner tube 2. At the tip, there is an auxiliary piston 4 that slides into inner tube 2, and below the inner tube 2, there is a piston 5 that slides into hollow pipe 3.
These outer tube 1, inner tube 2, hollow pipe 3, auxiliary piston 4, and piston 5 define a chamber A and a chamber B that generate a damping force when the hydraulic shock absorber is extended.

A movable partition member 11 is inserted into a case 12 fixedly provided below the outer tube 1 to form a chamber B/.

The chamber E is separated from oil to compensate for changes in oil amount due to the protruding volume of the inner tube 2, and is configured to balance the pressure of the air chamber through the hollow pipe 3. .

Reference numeral 13 denotes a valve body for generating a damping force during compression operation, and a passage 14 communicating between the chamber B and the chamber B' below it is bored, and a valve 1 for generating a damping force is installed above the passage 14.
5 are arranged.

In the compression operation of the hydraulic shock absorber, the valve 15 causes the oil corresponding to the volume entered into the inner tube to flow into the chamber B' side while generating a damping force by the orifice 15' bored in the valve 15, and in the expansion operation, the valve 15 moves upward. The oil in chamber B' is moved to chamber B and opened, and the oil in chamber B' is supplied to chamber B without resistance.

A hollow bolt 17 fixes the hollow pipe 3 to the inner tube 2 via the valve body 13.

The partition wall member 11 moves within the case 12 due to the inflow and outflow of oil in the chamber Bk, thereby compensating for the change in the amount of oil corresponding to the volume of the protruding inner tube 2.

As mentioned above, when the hydraulic shock absorber expands and contracts, the chamber E compensates for the change in oil amount due to the protruding volume of the inner tube 2, and the fluctuation of the oil level d in the oil reservoir chamber C is suppressed as much as possible, and the air chamber is connected to the inner tube. 2. It is designed to expand and contract only by vertical movement of the cap 16 at the upper end.

When setting the volume of the air chamber and chamber E, The volume of the air chamber is VD The volume of chamber E is VE AD the cross-sectional area of the inner tube AE the inner diameter cross-sectional area of the inner tube Then It is desirable to make it so that

That is, since the air chamber and chamber B' communicate through the hollow pipe 3 and are configured to always maintain a pressure equilibrium state through oil, for example, in the relationship of the above equation, the air chamber When the volume VD of is large, part of the oil corresponding to the intrusion volume of the inner tube 2 flows into the oil reservoir chamber C during the compression operation of the hydraulic shock absorber and the pressure is balanced, and on the other hand, the volume of the air chamber VD is small. The oil corresponding to the intrusion volume of the inner tube 2 and a part of the oil in the oil reservoir chamber C flow into the chamber W side, and the pressure is balanced.

If the volumes of the air chamber and chamber E are set at a ratio that prevents oil volume changes in oil sump chamber C, an optimal hydraulic shock absorber can be created without causing oil volume changes in oil sump chamber C. It will be understood that a telescopic action can be obtained.

However, in actual design, it is necessary to take into consideration the operating resistance of the partition wall member 11, oil leakage from the sliding contact portion between the auxiliary piston 4 and the inner tube 2, and the like.

In FIG. 1, the partition wall member 11 is composed of a free piston that moves the case 12, but in FIG.
The interior is divided into chambers B' and E', and above the bellows 11a,
In order to prevent the bellows 11a from blocking the passage 17' of the bolt 170, a guide plate 18 having an appropriate number of through holes 18a is provided.

FIG. 3 shows another embodiment of the present invention, in which a case 12 is integrally connected to the lower part of the outer cylinder.
Inside z, a bellows 11b that bulges out from the bottom to the top is arranged to be expandable and retractable, thereby dividing the chamber pi and r in the case 12'.In this case, the bellows 11b bulges out to the maximum. Since the holes 17' of the bolts 17 are not blocked even when the bolts 17 are inserted, there is no need for a guide plate as shown in FIG.

FIG. 4 shows another embodiment of the present invention, in which case 1
It is easy to understand that the hole 20 is provided at the lower end of 2 to open it to the atmosphere, and the partition wall member 11 is supported by a spring 19 that approximates the spring characteristics of the air chamber, and that it has the same effect as described above. .

As mentioned above, in the present invention, in order to minimize changes in the amount of oil in the oil reservoir chamber C, a chamber E for compensating for changes in the amount of oil corresponding to the volume of the protruding inner tube is provided separately from the air chamber, with oil communicating therewith. , the change in the amount of oil in the oil reservoir chamber C is minimized to prevent oil from entering or being dragged into the reservoir, thereby obtaining suitable hydraulic shock absorbing characteristics.

Furthermore, the air chamber and the inner tube protrusion/input volume compensation chamber E
By setting the volume ratio by the ratio of the inner diameter cross-sectional area of the inner tube to the cross-sectional area of the inner tube, changes in the amount of oil in the oil reservoir chamber C can be further reduced and empty packages can be prevented from getting mixed in or caught in the reservoir. The aim is to obtain suitable hydraulic damping characteristics.

In addition, by movably disposing a partition wall member that seals oil in opposition to the air chamber, and supporting the partition wall member with a spring member that approximates the spring characteristics of the air chamber, the amount of oil in the oil storage chamber C can be reduced. The purpose is to reduce the change in pressure, prevent air from entering the pond, and obtain suitable hydraulic shock absorbing characteristics.

Further, by disposing a valve for generating a damping force during the compression operation of the hydraulic shock absorber between the chambers B and W, it is possible to obtain damping force characteristics with a relatively simple structure. It's a big deal.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional side view of a hydraulic shock absorber according to one embodiment of the present invention, FIGS. 2, 3, and 4 are partially cutaway vertical side views of hydraulic shock absorbers according to other embodiments, FIG. 5 is a longitudinal sectional side view of a conventional hydraulic shock absorber. 1... Outer tube, 2... Inner tube, 11... Partition member, ILa...
...Bello, 15...Valve, 18a...
...Guide plate, 19...Spring member,
D...air chamber, E...chamber.

Claims (1)

[Claims] 1. In a hydraulic shock absorber in which an inner tube is slidably inserted into an outer tube, an oil reservoir chamber located above the inner tube and an air chamber located above the oil reservoir chamber are provided. and a chamber that is independent from the air chamber and communicates with the lower oil chamber in the outer tube, and a hollow pipe that communicates the oil reservoir chamber and the lower oil chamber with each other, and the volume ratio of the air chamber and the chamber is adjusted. Hydraulic shock absorber set according to the ratio of the inner diameter cross-sectional area of the inner tube to the cross-sectional area of the inner tube. 2. The hydraulic shock absorber according to claim 1, wherein the volume ratio of the air chamber to the chamber is equal to the ratio of the inner diameter cross-sectional area of the inner tube to the cross-sectional area of the inner tube. 3. The hydraulic shock absorber according to claim 1, wherein the chamber is located at the lower end of the outer tube and partitioned by a partition member. 4. The hydraulic shock absorber according to claim 3, wherein the partition member is constituted by a free piston. 5. The hydraulic shock absorber according to claim 3, wherein the partition member is constituted by a bellows made of rubber.