JPS6118266Y2 - - Google Patents

Description

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

As a hydraulic shock absorber with variable damping characteristics, for example, the applicant has already filed an application as shown in FIG. 1 is an outer tube, 2 is an inner tube that slides on the inner periphery of the outer tube 1, and 3 is a hollow pipe whose base end is fixed to the outer tube 1 and that slides relatively on the inner periphery of the inner tube 2 via a piston 4. , 5 is a suspension spring that is interposed between the inner upper end of the inner tube 2 and the piston 4 and urges the inner tube 2 toward the expansion side. In addition, below the piston 4, there are provided an oil chamber C whose volume expands during pressure side operation and an oil chamber D whose volume contracts in the opposite direction. It communicates with an oil passage E provided in the base part 6 through the inside of the base part 6.

Then, the flow path 7 communicating between the oil reservoir chamber B and the oil chamber D is throttled in response to the pressure generated in the oil reservoir chamber B, whose internal pressure changes according to the change in the intrusion volume depending on the stroke position of the inner tube 2. A valve device 8 is provided on the outside of the outer tube 1 so that a large amount of energy can be absorbed during sudden pressure-side operation, thereby simultaneously improving riding comfort and maneuverability.

That is, since the pressure of the hydraulic oil in the oil reservoir chamber B rises in proportion to the compression stroke of the inner tube 2, for example, if the vehicle rides on a large bump on the road surface or suddenly stops, the inner tube 2 When the compressor is operated with a large stroke, the hydraulic oil level rises, the air chamber A is compressed, and the internal pressure rises to a predetermined pressure.
act on the end surface 9a of the spool 9, and move the spool 9, which is open to the atmosphere with the other end protruding outside, in the valve closing direction against the biasing force of the spring 30, thereby opening the flow path (port) 7. Narrow down. As a result, when the oil reservoir chamber B rises to a predetermined pressure after the start of compression,
The flow of hydraulic oil pushed out from the oil chamber D to the oil chamber F and directed toward the oil reservoir chamber B is immediately restricted, and significant sinking of the inner tube 2 is suppressed, resulting in improved maneuverability. Note that the shape of the spool 9 is such that the inner diameter of the port 7 on one side of the oil chamber F and the external protruding diameter of the spool 9 on the other side are approximately the same to maintain hydraulic balance, so that the inner tube 2 does not enter the oil chamber D. Even if pressure fluctuations that occur depending on the speed act on the oil chamber F, the spool 9 does not generate thrust in the axial direction. It is almost independent, and depends only on the internal pressure (strictly speaking, on the differential pressure between the internal pressure and the atmospheric pressure), which increases in accordance with the penetration stroke.

However, in such a conventional hydraulic shock absorber, the valve portion (valve body) 10 of the spool 9 that throttles the flow path 7
Since the initial position of the flow path 7 is always set at a predetermined position, the initial opening area (initial effective area) of the flow path 7 is always constant, and the damping force characteristics can be adjusted arbitrarily according to the riding state, riding conditions, rider preference, etc. The problem was that it couldn't be changed.

Therefore, this invention solves the above problem by forming the spool from a cylindrical outer spool and an inner spool that is screwed onto the inner circumference of the outer spool, and by making the initial position of the valve part freely adjustable. It is intended to.

Hereinafter, embodiments of this invention will be described based on the drawings.

In FIGS. 2 and 3, 11 is a valve device fixed to the outer circumference of the outer tube 1 that makes the compression side damping force variable; 12 is the body of the valve device 11; and 13 is a valve screwed inside the body 12. The upper bearing 14 is also a lower bearing 1 which is secured to the inside of the body 12 with a pin or washer 15 or the like.
6a is an annular outer spool that slides on the inner periphery of both bearings 13 and 14; 16b is an inner spool that is inserted into the inner periphery and screwed through threaded portion 35;
A port (flow path or orifice) 17 formed in the lower bearing 14 partitions an upstream chamber 18 and a downstream chamber 19 . The upstream chamber 18 communicates with an oil chamber D at the inner end of the outer tube 1 that contracts during pressure side operation, and the downstream chamber 19 communicates with an oil reservoir chamber B through an oil passage E provided in the base portion 6. .

Port 17 is located at the rear of the inner spool 16b.
An annular conical valve (valve body) 20 that relatively narrows the effective cross-sectional area of the spool in accordance with the working oil pressure is slidably mounted, and the valve 20 is disposed on the downstream chamber 19 side and is attached to the spool. It is urged to abut against the stepped portion 24 by a coil spring 22 interposed between the valve 20 and a nut 21 screwed onto the base end of the valve 16b.

A tapered surface 23 formed on the upstream chamber 18 side of the valve 20 serves as a hydraulic pressure receiving surface that receives the working oil pressure of the upstream chamber 18, while the nut 21 allows the initial load of the spring 22 to be freely adjusted.
Further, the upper end surfaces 25 of both spools 16a, 16b serve as air pressure receiving surfaces that receive pressure from the atmosphere or sealed pressure gas.

A return spring 26 is interposed between the upper bearing 13 and an annular spring receiver 123 fixed to the outer periphery of the outer spool 16a that moves integrally with the inner spool 16b.
6 is both spools 16a, 16 against the hydraulic pressure.
b is normally urged downstream until the spring receiver 123 comes into contact with the bearing. In addition, the upper bearing 13
A spring chamber 27 is formed between the lower bearing 14 and the spring 26 is disposed between both spools 16a and 1.
It communicates with the downstream chamber 19 through an oil passage 28 penetrating through 6b. The rest of the configuration is substantially the same as that of the conventional example shown in FIG. 1, so it is omitted.

With the configuration described above, when the upper bearing 13 is screwed forward relative to the body 12, the spring 26 expands and contracts, and its set load changes. Similarly, by threading the inner spool 16b relative to the outer spool 16a, the initial position of the valve 20 relative to the port 17 changes. Furthermore, by adjusting the position of the nut 21 before assembly, the set load of the spring 22 that biases the valve 20 can be changed.

In a stationary state, the port 17 has a predetermined effective cross-sectional area and is open due to the balance between the differential pressure between the pressure receiving surfaces 23 to 25 and the biasing forces of the springs 22 and 26.

Next, the inner tube 2 is compressed and the oil chamber D
At the same time as the oil is compressed, the hydraulic oil is pushed out from the oil chamber D and flows from the oil passage E to the oil reservoir chamber B through the valve device 11, or when adjusting the damping force characteristics, an orifice ( (not shown) to the oil reservoir chamber B through the hollow pipe 3.
At the same time, the air chamber A is compressed by an amount corresponding to the intrusion volume of the inner tube 2, thereby increasing the pressure in the oil reservoir chamber B. This pressure increase in the oil reservoir chamber B is instantaneously transmitted to the hydraulic pressure receiving surfaces of the spools 16a and 16b, and the axial thrust obtained by the pressure increase acting on the radial cross-sectional area of both spool seals 36, that is, the spool 16a, 16b
At this time, the spool upper end surface 25 remains at approximately atmospheric pressure and the force pushing back the spools 16a, 16b does not change, so the spools 16a, 16b are moved by the spring 26. moves upward against the urging force of As a result, the valve 20 throttles the effective cross-sectional area of the port 17 in proportion to the pressure rise according to the compression stroke amount, restricts the flow from the oil chamber D to the oil reservoir chamber B during compression operation, and corresponds to the stroke. generates a damping force.

In this case, the spools 16a, 16b do not move due to pressure fluctuations depending on the speed of entry of the inner tube 2, as in the conventional case. That is, port 1
7 and the spool 16 passing through the seal portion 36
Since the effective cross-sectional areas of the spools a and 16b are equal, the pressure of the spools 16a and 16b is balanced in the axial direction in the upstream chamber 18, and the spools 16a and 16b are not subjected to axial thrust due to the above pressure fluctuation. Even if the pressure change D acts on the spools 16a, 16b, no axial thrust is generated, so the spools 16a, 16b do not move depending on this.

However, during this compression operation, the valve 20 fitted into the spool 16b is not connected to the spool 1.
6b, but the oil pressure in the upstream chamber 18 that communicates with the oil chamber D and the downstream chamber 1 that communicates with the oil reservoir chamber B.
9 can be received by the pressure-receiving surface 23 and released independently of the spool 16b downward (to the right in the drawing) against the spring 22, so that the opening degree of the valve 20 can be changed is determined based on the balance between the differential pressure generated at the spool position and the spring 22. Therefore, the opening degree of the valve 20 that generates the damping force basically depends on the stroke position, and as the compression stroke amount increases, the higher the damping force is generated, but it also depends on the penetration speed of the inner tube 2 at that time. When the pressure in the oil chamber D suddenly increases beyond the value set by the spring 22, it opens to prevent shocks from the road surface from being transmitted to the vehicle body.

By the way, in this invention, especially the inner spool 1
6b to the outer spool 16a through the threaded portion 35 (of course, the inner spool 16b can also be moved forward and backward relative to the outer spool 16a using a cam member, etc.), the valve for the port 17 The initial position of 20 changes and port 1
The initial opening area of 7 can be varied.

As a result, the damping force characteristics can be variably set depending on the course state, driving conditions, driver's preference, etc.

As explained above, according to this invention, the initial opening area of the port can be changed arbitrarily, so the attenuation characteristics can be variably set according to the requirements.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a conventional device, FIG. 2 is a longitudinal sectional view of a main part of an embodiment of the present invention, and FIG. 3 is a right side view of FIG. 2. A...Air chamber, B...Oil reservoir chamber, C, D...Oil chamber, E...Oil passage, 11...Valve device, 12...
Body, 13, 14...Bearing, 16a, 16b...
...Spool, 17...Port, 18...Upstream chamber,
19... Downstream chamber, 20... Valve, 21... Hot, 22... Spring, 23, 24... Hydraulic pressure receiving surface, 25... Air pressure receiving surface, 26... Spring, 35... Threaded portion.

Claims (1)

[Scope of utility model registration request] It has an internal air chamber and an oil reservoir chamber, as well as an oil chamber whose internal pressure changes depending on the stroke position, and the flow between the oil reservoir chamber and oil chamber is adjusted in response to the pressure generated in the oil reservoir chamber. In a hydraulic shock absorber equipped with a valve device that narrows the flow path, a spool that narrows the flow path according to the pressure generated in the oil reservoir chamber is arranged on a cylindrical outer spool and a valve that is movable in the axial direction on the inner circumference of the spool. A hydraulic shock absorber comprising: an inner spool having an inner spool;