JPH0243055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic shock absorber whose damping force can be freely adjusted according to driving conditions, and particularly relates to an improvement of a front fork used as a shock absorber for the front wheel of a two-wheeled vehicle.

The damping characteristics required of a hydraulic shock absorber for a vehicle vary widely depending on driving conditions, but a normal hydraulic shock absorber can only provide preset fixed characteristics.

Therefore, the present applicant proposed, in Japanese Patent Application No. 56-55213, that the opening pressure of the damping valve can be increased or decreased by the excitation attraction force of an electromagnetic solenoid, and the damping characteristics can be arbitrarily changed according to the external current value. A hydraulic shock absorber was proposed.

However, in this case, because the damping valve installed in the piston is controlled by an electromagnetic solenoid,
The wiring for the solenoid coil must pass through the piston rod, and the structure of the piston may require major modifications, so in practical terms there are problems that need to be improved, such as durability, ease of assembly, and increased cost. There were many.

The present invention was proposed to solve this problem.

To this end, the present invention forms an oil chamber between an inner tube and an outer tube in the front fork of a two-wheeled vehicle, and uses a conduit arranged outside the outer tube to collect the hydraulic oil that flows out from this oil chamber during the extension side operation. The oil is released to the oil chamber (communicated with the oil reservoir chamber) below the outer tube through the pipe, and a damping valve is interposed in the middle of this pipe, and the opening characteristics of this damping valve are increased or decreased by an electromagnetic solenoid. .

Examples will be described below based on the drawings.

Inside the outer tube 1 attached to the axle side, there is an inner tube 2, which has a piston portion 8.
The upper oil chamber 4 is slidably housed in the outer tube 1 via the bearing portion 9 of the outer tube 1, and an annular upper oil chamber 4 is defined between the outer tube 1 and the inner tube 2.

Inside the outer tube 1, a hollow tube 3 is installed coaxially with the outer tube 1, and is in sliding contact with the inner periphery of the inner tube 2 through its distal end bearing portion 7.

The lower end of the suspension spring 12 is in contact with the upper part of the hollow cylinder 3, and this part serves as an oil reservoir chamber 13 in which gas is sealed in the upper part.

A pressure side check valve 11 is provided on the inner periphery of the piston portion 8 of the inner tube 2, thereby creating an oil chamber 6 between the inner tube 2 and the hollow cylinder 3, and a lower part between the outer tube 1 and the hollow cylinder 3. Each of them defines an oil chamber 5.

The oil chamber 6 is formed through a port 1 formed in the inner tube 2.
0 communicates with the upper oil chamber 4, and the lower oil chamber 5 communicates with the oil reservoir chamber 13 through a port 14 formed in the hollow cylinder 3.

The outer tube 1 is provided with a communication port 26 that communicates with the upper oil chamber 4 and a communication port 30 that also communicates with the lower oil chamber 5. The connection is made via the pipe line 29 provided.

The expansion-side damping valve 15 is interposed in the middle of the pipe line 29.

The expansion side damping valve 15 has a cylindrical valve housing 16 fixed to the outside of the outer tube 1.
A support shaft 18 is fixed concentrically inside the housing 16, and an electromagnetic solenoid 17 is attached to the support shaft 18.
A coil 25 is wound around the bobbin 22, and a valve seat 21 made of a magnetic material is attached to the lower part of the bobbin 22.

A valve port 27 is formed in the valve seat portion 21, and a valve 19 made of a magnetic material that closes the valve port 27 with a spring 20 comes into elastic contact.

The upper part of the support shaft 18 projects outward from the housing 16, and a vertical hole 23 is coaxially formed in this projecting portion, and a rieet wire 24 connected to the coil 25 is disposed in the vertical hole 23.

A passage 32 formed in the housing 16 is connected to the communication port 26, and an outer circumferential passage 33 of the coil 25 is connected to the communication port 26.
It communicates with the valve port 27 via.

In addition, a conduit 2 is provided at the bottom of the valve housing 16.
9 connection ports 28 are provided to guide hydraulic oil from the valve chamber 34 to a conduit 29.

The other end of the conduit 29 is connected to a communication port 30 at the bottom of the outer tube 1 via a joint 31.

The system is constructed as described above, and its operation will be explained next.

In the compression side stroke in which the inner tube 2 advances into the outer tube 1 while compressing the spring 12, both the upper oil chambers 4 and 6 expand, and the lower oil chamber 5 contracts.

Therefore, part of the hydraulic oil in the oil chamber 5 moves upward via the check valve 11, and excess oil corresponding to the volume of entry into the inner tube 2 flows into the oil reservoir chamber 13.
through the port 14.

At this time, the expansion side damping valve 15
Since the pressure on the side is low, the valve 19 is closed in close contact with the valve seat portion 21, and hydraulic oil is not sucked into the oil chamber 4 from the pipe line 29.

Therefore, the damping force in the compression stroke is extremely low.

On the other hand, when the inner tube 2 is pulled out during the extension operation, the upper oil chambers 4 and 6 are contracted, and the lower oil chamber 5 is expanded.

At this time, check valve 1 is kept closed, so
The hydraulic oil in the oil chamber 6 flows into the oil chamber 4 from the passage 10, and together with the hydraulic oil in the oil chamber 4, it reaches the valve port 27 through the passage 26 of the expansion damping valve 15, the outer circumferential passage 33, and the spring 20. Valve 1 against
9 and flows into the valve chamber 34.

The resistance force of the valve 19 at this time acts as a damping force on the expansion side, and the operating oil flows from the valve chamber 34 via the conduit 29 to the expanding oil chamber 5 on the low pressure side.

When the electromagnetic solenoid 17 is energized and excited, the valve seat 21 is magnetized and the valve 19 is attracted. In order to open the valve 19, the elastic force of the spring 20 and the attraction force of the electromagnetic solenoid 17 must be overcome.

Therefore, the damping force generated by the valve 19 changes according to the excitation force of the electromagnetic solenoid 17, and as the excitation current is strengthened, the generated damping force increases proportionally.

The amount of current supplied to the electromagnetic solenoid 17 may be controlled by a control circuit (not shown) based on the outputs of various sensors that detect operating conditions.

As described above, according to the present invention, the rebound damping force of the front fork can be freely controlled according to the driving conditions, improving handling and riding comfort. Since it can be attached to the piston rod, there is no need to wire the electromagnetic solenoid inside the piston rod or modify the piston part, and it can be easily installed using the existing front fork.
It has excellent productivity and ease of assembly, as well as improved durability and reliability.

[Brief explanation of the drawing]

The drawings are cross-sectional views showing embodiments of the present invention. 1... Outer tube, 2... Inner tube, 3... Hollow cylinder, 4, 5, 6... Oil chamber, 8...
... Piston part, 10 ... Port, 11 ... Check valve, 15 ... Extension side damping valve, 17 ... Electromagnetic solenoid, 19 ... Valve, 20 ... Spring,
21... Valve seat portion, 25... Coil, 26, 30...
...Communication port, 29...Pipe line.

Claims (1)

[Claims] 1. An upper oil chamber is formed between the inner tube and the outer tube via the piston part, and a lower oil chamber communicating with the oil reservoir chamber is formed on the lower surface of the piston, and a pipe line arranged on the outside of the outer tube is formed. communicating the upper oil chamber and the lower oil chamber through the
A front fork characterized in that a growth-side damping valve is interposed in the middle of the conduit, and an electromagnetic solenoid is provided to increase or decrease the opening pressure of the growth-side damping valve in accordance with an exciting current.