JPS6235955Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a pressure-sensing hydraulic shock absorber mainly used in vehicles such as two-wheeled vehicles.

(Prior Art and Problems to be Solved by the Present Invention) Conventionally, the applicant has proposed a hydraulic shock absorber that changes the damping force by sensing the internal pressure generated in accordance with the stroke. There is. However, in this case, since the spool valve was configured to sense the internal pressure and throttle the flow path, the damping characteristics were uniquely determined, and it was not possible to satisfy all required damping characteristics that varied depending on the operating conditions.

This idea was made to solve this problem, and by making the initial load of the relief valve and the restriction of the passage variable in accordance with the internal pressure, it was possible to provide optimal damping characteristics according to the requirements. The purpose is to provide a buffer.

(Means for solving the problem) It has a sealed volume compensation air chamber and an oil sump chamber inside, and the internal pressure changes depending on the stroke position.It damps according to the pressure generated in the oil sump chamber. In a hydraulic shock absorber equipped with a valve device that changes force,
In the middle of the oil passage connecting the inner oil chamber and the outer oil chamber, a bottomed cylindrical spool that responds to the differential pressure between the pressure in the oil reservoir chamber and atmospheric pressure is installed in the cylinder part so that it can freely slide. Forming two throttle passages whose opening degree changes with displacement, and providing a relief valve that bypasses the throttle passages and releases the pressure side hydraulic oil,
In addition, the area of the one throttle passage is made variable depending on the valve position of the relief valve.

(Example) An example of this invention will be described below based on the drawings.

First, to explain the configuration, as shown in Figure 1,
A stepped cylindrical body with a closed circumferential portion is located in the central end of the outer tube 1, and a port 2 is provided in the small diameter stepped portion 23A.
5 is provided in the radial direction, and an orifice 2 is provided in the axial direction on the flat part of the medium diameter step part 23B that contacts the small diameter step part.
6, and a port 27 at the end of the large diameter end 23C.
The cylinder part 23 provided with is arranged as a support,
The end portion of the cylinder portion 24, on which the piston 35 slides, is fixedly fitted into this medium diameter stepped portion 23B.

Further, a washer-shaped relief valve 31 is disposed in the inner diameter stepped portion 23D between the orifice 26 and the port 27 of the cylinder portion 23, supported by a spring 32 having a biasing force on the orifice 26 side.

Next, a bottomed cylindrical spool 6 is housed from the inner diameter part of the cylinder part 23 to the end hole part 22 of the outer tube 1 which is exposed to the atmosphere, and is slidable in the axial direction, and is fixed to the proximal peripheral part of the spool. A return spring 34 is interposed between the washer 33 and the terminal of the outer tube 1. Further, on the circumferential surface of the spool 6, a port 25 of the cylinder portion 23 is provided.
A throttle passage 28 is provided at a position that matches the space between the orifice 26 and the relief valve 31, a throttle passage 29 is provided at a position that matches the air space between the orifice 26 and the relief valve 31, and a passage 30 is provided between the relief valve 31 and the washer 33. be. Note that the inner oil chamber K inside the cylinder 24
are port 25, throttle passage 28 and orifice 2
6. The throttle passage 29 communicates with the outer oil chamber L via the passage 30 and the port 27. The throttle passages 28, 29 and the relief valve 31 constitute a valve device that changes the damping force according to the internal pressure. Therefore, when the inner tube is compressed and receives the pressing force of the piston 35, the inner oil chamber K contracts, and the hydraulic oil corresponding to the volume that enters the piston rod flows into the port 25, the throttle passage 28, the orifice 26,
It enters the spool 6 from both of the throttle passages 29 and flows to the outer oil chamber L side through the passage 30 and the port 27, but due to the pressure rise on the oil sump chamber side caused by this, the spool 6 is forced into the outer tube 1. It moves to the terminal hole 22 side which is exposed to the atmosphere. This amount of movement increases as the internal pressure increases, that is, as the intrusion stroke amount of the piston 35 increases.

As a result, the degree of communication between the port 25 and the throttle passage 28 decreases, and as shown in FIG.
The throttle passage 29 located just before the spool 6
As shown in FIG. 3, the relief valve 3
1 and the diameter decreases, the oil passage from the inner oil chamber K is narrowed and the flow to the outer oil chamber L is restricted, so the damping force increases. If the spool 6 continues to move due to an increase in the piston stroke amount, the diameter of the throttle passage 29 becomes close to zero in FIG. 4, and becomes zero in FIG. 5. In this way, the area of the throttle passages 28 and 29 is reduced,
When the upstream pressure of the throttle increases, the relief valve 31 opens when this pressure value exceeds the set load determined by the spring 32 of the relief valve 31, and the hydraulic oil bypasses the throttle passages 28 and 29 to the port 27.
from there to the outer oil chamber L.

This relationship is shown in FIG. 6, where the vertical axis represents the damping force C and the horizontal axis represents the speed D. E is the damping characteristic of the throttle passages 28, 29 under the condition shown in FIG. 2, F is the damping characteristic of the throttle passages 28, 29 and the relief valve 31 under the condition of FIG. This is the damping characteristic due to the throttle passage 28 and the relief valve 31 under the condition shown in FIG.
As for the damping characteristic of G, since the throttle passage 29 has a circular shape, the flow rate relative to the lift amount is smaller than that of F, so that the damping force curve becomes steeper. H is the damping characteristic due to the throttle passage 28 and the relief valve 31 under the condition shown in FIG. It gets expensive.

(Effects of the invention) As explained above, this invention makes the restriction of the passage provided in parallel with the relief valve variable according to the internal pressure, and increases the damping force as the piston stroke becomes larger. In areas where the stroke amount is large, the throttle passage is enlarged to improve ride comfort, and in areas where the stroke amount is large, the throttle passage is closed to prevent bottoming out.The optimal damping force can be obtained depending on good operating conditions, improving responsiveness and improving ride comfort. It has the effect of improving maneuverability.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of the main parts showing the valve device of a hydraulic shock absorber according to the first embodiment of the invention, FIG. 2 is a detailed view of the main parts showing the positional relationship between the throttle passage and the relief valve before the start of operation, and FIG. Figures 3A and 3B are detailed views of main parts showing the positional relationship between the throttle passage and the relief valve at the early stage of operation of the same embodiment, and Figures 4A and 4B are the positional relationship between the throttle passage and the relief valve at the middle stage of the operation of the same embodiment. Figures 5A and 5B are detailed views of the main parts showing the positional relationship between the throttle passage and the relief valve in the latter stage of operation of the same embodiment, and Figure 6 is the relationship between damping force and speed in the same embodiment. This is a graph showing. 6...Spool, 31...Relief valve, 34...
...Return spring, 32...Spring, 2
8, 29... throttle passage, 25, 27... port,
23... Cylinder part, 26... Orifice, L...
...Outer oil chamber, K...Inner oil chamber.

Claims (1)

[Scope of utility model registration request] It has a sealed volume compensation air chamber and an oil reservoir chamber inside, and is equipped with a valve device that changes the damping force according to the pressure generated in the oil reservoir chamber whose internal pressure changes according to the stroke position. In hydraulic shock absorbers,
In the middle of the oil passage connecting the inner oil chamber and the outer oil chamber, a bottomed cylindrical spool that responds to the differential pressure between the pressure in the oil reservoir chamber and atmospheric pressure is installed in the cylinder section so that it can freely slide. Two throttle passages whose opening degree changes with displacement are formed, and a relief valve is provided that bypasses these throttle passages to release the pressure side hydraulic oil, and the position of the one throttle passage is determined by the valve position of the relief valve. A hydraulic shock absorber characterized by a variable area.