JPS6342139B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a damping force generating device in a hydraulic shock absorber, and more specifically, in a hydraulic shock absorber incorporating a hollow piston rod, a plurality of compression side damping force generating mechanisms are provided in the hollow piston rod. The present invention relates to a damping force generating device in which a compression side damping force is increased or decreased depending on an excitation position.

Generally speaking, in a hydraulic shock absorber in which a hollow piston rod is disposed within a cylinder via a piston, and hydraulic oil and gas chambers are provided within this piston rod, this hydraulic shock absorber is disposed between the vehicle wheels and the vehicle body. In this case, the weight of the vehicle varies between when it is loaded and when it is empty, so it is necessary to have optimal damping force characteristics according to each weight. However, when there is only one damping force generation mechanism, such as in a conventional hydraulic shock absorber, the damping force can only be obtained according to the damping force generation mechanism, and the damping force can only be obtained according to the vehicle weight, or in other words, the vehicle height position. It is impossible to obtain damping force.

In addition, if the oil level is in direct contact with the air chamber in the hollow piston rod, a jet flow will be generated in the gas in the air chamber when the piston rod expands and contracts, and if this gets mixed into the hydraulic oil, aeration will occur and the damping force characteristics will change. It has the disadvantage that it decreases.

Therefore, an object of the present invention is to arrange a plurality of bubble stopper plates in a hollow piston rod, and to provide a compression side damping force generating mechanism consisting of an orifice or a valve on the bubble stopper plates, thereby controlling the damping force when the car is loaded and when the car is empty. A two-wheeled vehicle, a four-wheeled vehicle, etc., which can obtain a damping force according to the vehicle height position even when the vehicle height position changes, and the gas in the air chamber is blocked by a bubble stopper plate to prevent aeration. It is an object of the present invention to provide a damping force generating device in a hydraulic shock absorber suitable for use in a damper.

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, a hollow piston rod 3 is slidably inserted into a cylinder 1 via a piston 2, the piston 2 partitions two upper and lower oil chambers 4 and 5 into the cylinder 1, and the piston rod 3 is slidably inserted into the cylinder 1 via a piston 2. Seal 6
and protrudes to the outside via the bearing 7.

Built into the piston 2 are a valve 8 for generating a damping force on the rebound side, and a check valve 9 that allows oil to flow from the oil chamber 5 to the oil chamber 4.

There are two bubble stoppers 1 inside the hollow piston rod 3.
0 and 11 are fixed horizontally, and this bubble stopper plate 10,
11, there is a chamber 12,1 in the piston rod 3.
3 and 14 are divided. In these chambers 12, 13, and 14, for example, when the vehicle is empty, the oil level of the hydraulic oil is at the position _l1 , and at this time, the chambers above the oil level _l1 serve as gas chambers. When the vehicle is loaded, the piston rod 3 is lowered and the oil level rises to _l2 , and a gas chamber is defined above this oil level _l2 . Note that the chamber 12 opens into the lower oil chamber 4 via a hollow portion 18.

In the embodiment shown in FIG. 1, two bubble stopper plates 10 and 11 are provided, but more than that number can also be used.

The bubble stopper plates 10 and 11 have built-in an orifice 15 as a throttle mechanism for generating compression damping force, and a check valve 16 that allows oil to flow from the upper chamber 13 or 14 to the lower chamber 12 or 13. .

When the hydraulic shock absorber shown in Fig. 1 is installed on the axle side of the vehicle through the eye 17, and the upper end of the piston rod 3 is installed on the vehicle body side through the bracket, for example, when the vehicle is empty, piston rod 3
The oil level inside is at position _l1 , the only thing that generates damping force is the lower bubble stopper plate 10, and the upper bubble stopper plate 11 is in the gas chamber.

For this reason, for example, when the piston 2 extends, the oil chamber 4 contracts and the lower oil chamber 5 expands.
The internal pressure of the oil chamber 4 rises, and the discharged oil flows out into the lower oil chamber 5 through the valve 8, and this valve 8 generates a damping force during expansion. In addition, the oil in the oil chambers 12 and 13 inside the piston rod 3 also flows from the hollow portion 18 to the lower oil chamber 5.
leaks into

Also, when the piston 2 descends, the lower oil chamber 5 contracts,
Since the upper oil chamber 4 expands, the oil in the oil chamber 5 flows into the upper oil chamber 5 through the check valve 9, and the oil in the oil chamber 5 and chamber 12 also flows through the orifice 15 of the lower bubble stopper plate 10. The fluid is discharged into the chamber 13, and the flow resistance of the orifice 15 generates a compression damping force. The compression side damping force orifice characteristic at this time is shown by curve a in FIG.

Next, when the vehicle is loaded, the piston rod 3 is compressed, and if the vehicle height is lowered, the piston rod 3 is compressed.
The oil level inside fluctuates to the l ₂ position. Therefore, the two bubble stopper plates 10 and 11 are located in the oil, and the two orifices 15 and 15 all generate damping force.

That is, during compression, the oil in the chamber 12 is absorbed by the bubble stopper plate 10.
The oil in the chamber 13 flows out through the orifice 15 of the upper bubble stopper plate 11 into the chamber 13.
Since the damping force flows out into the chamber 14 through the two orifices 15, 15, a compression side damping force is generated, and the damping force orifice characteristic at this time is shown by curve b in FIG.

As can be seen from the above characteristics a and b, the compression side damping force can be automatically changed depending on the excitation position of the piston rod 3, that is, the oil level positions l ₁ and l ₂ depending on whether the car is loaded or empty. Because it is possible, vehicle ride comfort,
Good handling stability and ground contact.

Moreover, since the bubble stopper plates 10 and 11 block the gas jet in the air chamber, aeration due to fluctuations in the oil level can be prevented, and the damping force characteristics can be stabilized.

Next, FIG. 2 shows another embodiment of the present invention, which incorporates valves 19, 20 as throttling mechanisms in place of the orifices 15, 15 provided in the bubble stopper plates 10, 11 of FIG. In this case, substantially the same as the orifices 15, 15 of FIG. 1, the compression side damping force can be obtained by the optimum valve characteristics depending on the loaded state and the empty state, respectively. The rest of the structure is exactly the same as that shown in FIG. 1, so the same reference numerals are given to each member.

Furthermore, FIG. 3 shows another embodiment of the present invention, in which the piston 2 is provided with a valve 8 for generating damping force on the rebound side.
Then, a valve 23 for generating a compression side damping force is provided, and the valve 8 opens when the pressure in the oil chamber 4 increases, for example, by the pilot pressure, and conversely, the valve 23 opens the oil chamber when the pressure rises. When the pressure at 5 increases, for example, the pilot pressure opens the valve body, and a damping force is generated depending on the degree of opening. However, the restriction of this valve 23 is such that the pressure in the oil chamber 4 during compression does not become lower than that in the chamber 14 of the piston rod 3.

Also, a plurality of bubble stopper plates 21 and 22 are horizontally fixed inside the hollow piston rod 3, and the bubble stopper plates 2
Orifices 24 and 25 are vertically bored in the holes 1 and 22 as throttling mechanisms, and compared to the one shown in FIG. 1, the check valve is eliminated. When the vehicle is empty, the oil level is _l1 , and when the vehicle is loaded, the oil level is _l2 , and the air chamber above the oil level _l1 or _l2 is prepressurized.

Therefore, during the extension operation, the oil chamber 4 contracts, the oil chamber 5 expands, and the operation of the valve 8 generates an extension-side damping force. Also, during compression operation, the oil chamber 5 contracts and the oil chamber 4 expands, but at this time, the pressure in the oil chamber 5 closes the valve 23.
opens, and the throttle generates a compression damping force due to the valve characteristics, and a portion of the hydraulic oil in the oil chamber 5 flows out from the chamber 12 to the chamber 13 or 14 via the orifices 24 or 25. , 25, a compression side damping force is generated due to the orifice characteristics.

That is, when the oil level is _l1 when the car is empty, the compression side damping force has a composite characteristic by the valve 23 and the orifice 24 as shown by curve c in Fig. 5, and when the oil level is loaded when the car is loaded,
When it is at _l2 , a composite characteristic d is obtained by the valve 23 and the orifices 24, 25 as shown by the curve d.

As described above, in the present invention, the compression side damping force increases or decreases depending on the excitation position of the hollow piston rod, so even if the weight of the vehicle changes, for example when it is loaded or empty, the optimum damping force characteristics can be obtained according to the weight. , vehicle ride comfort, handling stability, and ground contact are improved. In addition, the bubble stopper plates 10, 11, 21, and 22 block air jets, thereby preventing aeration and preventing deterioration of damping force characteristics.
This improves pressure rise delay.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are longitudinal sectional front views of a hydraulic shock absorber according to an embodiment of the present invention, and FIG.
FIG. 5 is a graph showing the characteristics of compression damping force with respect to piston speed. 1... Cylinder, 2... Piston, 3... Hollow piston rod, 4, 5... Oil chamber, 12, 13,
14... Chamber, 10, 11, 21, 22... Bubble stopper plate, 15, 24, 25... Orifice, 16...
Check valve, 19, 20...valve.

Claims (1)

[Claims] 1. A hollow piston rod is slidably inserted into the cylinder via the piston, and the piston defines two upper and lower oil chambers in the cylinder, and the chamber in the hollow piston rod communicates with the lower oil chamber. A damping force generating device for a hydraulic shock absorber in which a plurality of bubble stopper plates are installed at intervals within a hollow piston rod, and the bubble stopper plates are provided with a throttle mechanism for generating compression side damping force. 2. A damping force generating device in a hydraulic shock absorber according to claim 1, wherein the throttle mechanism is an orifice. 3 Claim 1 in which the throttle mechanism is a valve
A damping force generating device in the hydraulic shock absorber described in 2. 4. A damping force generating device in a hydraulic shock absorber according to claim 1, wherein a check valve is provided on the bubble stopper plate.