JP2695816B2 - Damping force adjustable front fork - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a front fork with a built-in damper that can freely change a generated damping force on a compression side.

(Conventional technology) As a motorcycle front fork with a built-in damper,
For example, there is Japanese Utility Model Application No. 61-1445698. The front fork with built-in damper is a telescopic outer tube,
The load is supported between the inner tube and the inner tube, and the damping force is generated by a built-in damper.

(Problems to be Solved by the Invention) However, in this case, in order to control the generated damping force on the extension side and the compression side, respectively, an extension side and a compression side attenuation valve are required, and one is the bottom of the cylinder of the damper and the other is the piston. Since it is incorporated in the horn, not only the structure becomes complicated but also the adjustment of the damping force is very troublesome.

In order to solve such a problem, an object of the present invention is to enable a single damping valve to generate a damping force on the extension side and a compression side.

(Means for Solving the Problems) The present invention accommodates the inner tubes in the outer tubes and incorporates a damper located inside these tubes,
In the front fork, which defines an oil reservoir for compensating the flow of hydraulic oil for the volume of the piston rod entering the damper inside the inner tube, a passage is formed through the piston rod of the damper, and the passage is formed above the inner tube. The oil reservoir communicates with the oil reservoir through a damping force adjustable damping valve provided at the end of the damper, and the piston side end of this passage is opened to the rod side oil chamber of the damper. A check valve for flowing hydraulic oil to the side oil chamber is provided,
In addition, a check valve is provided at the bottom of the cylinder for flowing hydraulic oil from the oil reservoir side to the opposite rod-side oil chamber.

(Operation) When the front fork operates, for example, on the compression side, the hydraulic oil in the non-rod-side oil chamber, which contracts, passes through the check valve of the piston to the rod-side oil chamber, and further flows into the rod-side oil chamber. Recirculates from the passage of the piston rod to the oil reservoir via the damping valve, and at this time, a compression damping force is generated according to the resistance of the damping valve.

On the other hand, when operating to the extension side, the hydraulic oil from the oil reservoir flows into the non-rod side oil chamber through the check valve without resistance, while the hydraulic oil in the contracting rod side oil chamber is Flows through the damping valve to the oil reservoir, and at this time, the extension-side damping force is generated in the same manner as described above.

(Embodiment) As shown in Fig. 1, an inner tube 2 is slidably inserted into an outer tube 1, and a damper 3 is housed inside these.

In the damper 3, a piston 5 attached to a piston rod 6 connected to the inner tube 2 is housed slidably in a cylinder 4, and the cylinder 4 stands upright on the bottom of the outer tube 1.

A non-rod side oil chamber 7 contracting at the time of the compression side operation and a rod side oil chamber 8 contracting at the time of the extension side operation are defined through the piston 5 inside the damper 3. The piston 5 is provided with a check valve 5A that opens only at the time of operation on the pressure side and allows the operating oil to flow from the non-rod side oil chamber 7 to the rod side oil chamber 8. An orifice 5B is formed in the valve plate of the check valve 5A,
A part of hydraulic oil is released from the rod-side oil chamber 8 to the non-rod-side oil chamber 7 during the extension-side operation.

Above the damper 3, an oil reservoir 9 is formed inside the inner tube 2, and the oil reservoir 9 is formed from an annular passage 10 outside the cylinder 4 through a check valve 4 </ b> A disposed at the bottom of the cylinder 4 ( (Base valve) and communicates with the non-rod side oil chamber 7. The check valve 4A allows the hydraulic oil to pass from the oil reservoir 9 to the non-rod side oil chamber 7 without resistance during the extension side operation.

A solenoid 11 is attached to the upper end of the inner tube 2, and a damping valve 12, which is used for pressure expansion and accommodated in a valve case 13, is disposed coaxially with the solenoid 11, and the piston rod 6 passes through the center of these. A passage 25 formed through the center of the piston rod 6 has one end open to the rod-side oil chamber 8 and the other end connected to the damping valve 12.
Open upstream of

A suspension spring is provided between the lower surface of the valve case 13 and the upper surface of the damper 3 via spring seats 14A and 14B.
14 is arranged.

The valve case 13 also serves as a cap, is formed in a cylindrical shape, and is screwed to the inner periphery of the inner tube 2 via a screw portion 15, and the solenoid 11 and the damping valve 12 are housed therein. I have. A bobbin 17 made of a non-magnetic material is attached to a piston rod 6 penetrating the center of the solenoid 11, and a coil 16 is wound around the bobbin 17.
Inside the hollow piston rod 6, a magnetic core 18 is inserted and fixed inside the coil 16 to close the end of the passage 25. The damping valve 12 has a valve seat 20 having a port 22 fixed to the outer periphery of the piston rod 6.
On the other hand, a disk-shaped valve 21 made of a magnetic material is arranged freely to come and go. The valve seat 20 has an inner peripheral portion formed of a magnetic material, and an outer peripheral portion having a port 22 closed by the valve 21 formed of a separate non-magnetic material.

Also, a valve case in which the outer periphery of the valve seat 20 is fitted.
13 is made of a magnetic material, and when the solenoid 11 is excited, a closed circuit magnetic path is formed from the piston rod 6 made of the magnetic material through the inner peripheral portion of the valve seat, the valve 21, and the valve case 13, The valve 21 is attracted to the valve seat 20 according to the value of the solenoid excitation current.

The passage 25 penetrating the inside of the piston rod 6 opens in detail through the orifice 26 to the rod-side oil chamber 8 and has an orifice with respect to a valve chamber 27 defined below the solenoid 11. The valve chamber 27 communicates with the oil reservoir 9 via the port 22.

The upper end of the piston rod 6 is fixed to the upper end of the solenoid 11 fixed inside the valve case 13 by a nut 31 via a washer 30 (however, as shown in the drawing, it can be crimped).

A lead wire 40 connected to the coil 16 is taken out from the upper end of the solenoid 11 which is open to the atmosphere. Lead
Reference numeral 40 penetrates a cap 41 fitted to the upper part of the valve case 13 and is connected to an external control circuit (not shown). The control circuit is for adjusting the damping force according to the operating conditions and the like. For example, at the time of braking, high-speed running, cornering, etc., the exciting current is supplied to the solenoid 11 to increase the generated damping force.

The operation is described below. First, when the front fork moves to the extension side, the hydraulic oil in the rod-side oil chamber 8 that contracts with the rise of the piston 5 closes the check valve 5A. Therefore, the oil flows from the passage 25 of the piston rod 6 to the oil reservoir 9 through the damping valve 12. In this case, when the damping valve 12 is open, the resistance to the flow of the hydraulic oil corresponds to the opening degree of the orifices 26 and 28,
Generates relatively small damping force.

On the other hand, when the solenoid 11 is energized, the coil 16 is excited, and the exciting force causes the valve 21 to be attracted to the valve seat 20 and the damping valve 12 to close. Therefore, in this state, the resistance against the hydraulic oil from the passage 25 increases, and a large damping force is generated. This damping force changes depending on the value of the exciting current to the solenoid 11, and the greater the exciting force, the greater the damping force.

A part of the hydraulic oil in the rod-side oil chamber 8 flows from the orifice 5B provided in the check valve 5A into the expanding non-rod-side oil chamber 7, and the check valve 4A at the bottom of the cylinder 4 connects the annular passage 10 to the annular passage 10. Hydraulic oil is sucked in without resistance. Therefore, the basic value of the extension side damping force can be adjusted by the opening degree of the orifice 5B.

On the other hand, when the front fork is operated on the pressure side, the hydraulic oil in the non-rod-side oil chamber 7 that contracts is all the check valve of the piston 5 because the check valve 4A at the cylinder bottom is closed.
5A is pushed open to flow into the expanding rod-side oil chamber 8.
Hydraulic oil corresponding to the integral volume of the piston rod 6 flows from the passage 25 of the piston rod 6 to the oil reservoir 9 via the damping valve 12. Therefore, a damping force is generated by the damping valve 12 in the same manner as described above.

In this manner, the damping force is controlled by the common damping valve 12 on both the extension side and the compression side, and in this embodiment, the excitation force of the solenoid 11 is adjusted to operate the extension side and the compression side generated damping force. It can be freely changed according to conditions and the like. For example, the damping force is increased by exciting the solenoid 11 at the time of braking, high-speed running, and even at the time of sudden start, so that the stability of the vehicle body posture is ensured, and at the time of low-speed running, the solenoid 11 is de-energized. The ride comfort can be improved by reducing the damping force.

Next, the embodiment of FIG. 2 is an example in which, instead of the damping valve 12 for automatically adjusting the damping force by the solenoid 11, a damping valve 12 capable of adjusting the damping force by manual operation is provided.

The valve element 50 of the damping valve 12 is biased by a spring 51 so as to close the seat 49 at the end of the passage 25 of the piston rod 6. A body that houses the valve body 50 and the spring 51
53 is screwed into the valve case 13 and has a nut 54 at its head.
By rotating, the initial compression force of the spring 51 changes.

The hydraulic oil from the passage 25 of the piston rod 6 is supplied to the damping valve 12
To open and flow from the valve chamber 27 to the oil reservoir 9.

Therefore, a damping force based on the resistance of the damping valve 12 is generated for the hydraulic oil in both the extension side and the compression side stroke. This damping force depends on the amount of screwing of the body 53 and the spring 51
It can be adjusted freely by increasing or decreasing the load.

(Effect of the Invention) As described above, according to the present invention, the hydraulic oil flows from the passage formed in the piston rod via the damping valve in any of the strokes on the extension side and the compression side. Thereby, the damping force on the extension side and the compression side can be generated. And since the damping valve was provided on the upper part of the inner tube,
Adjustment from the outside can be easily performed, and optimum damping force characteristics can be provided as required.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIG. 2 is a sectional view of a main part of another embodiment. 1 ... outer tube, 2 ... inner tube, 3
…… Damper, 4 …… Cylinder, 4A, 5A …… Check valve,
6 ... Piston rod, 7,8 ... Oil chamber, 9 ... Oil chamber, 1
2 ... damping valve, 14 ... suspension spring, 25 ... passage.

Claims (1)

(57) [Claims] An oil reservoir for accommodating an inner tube in an outer tube, a damper built inside the inner tube, and compensating for the flow of hydraulic oil into and out of the inner tube by an amount corresponding to a piston rod penetration volume of the damper. In the front fork defining the chamber, a passage is formed through the piston rod of the damper, and this passage is communicated with the oil reservoir via a damping force adjustable damping valve provided above the inner tube, The piston-side end of this passage is opened to the rod-side oil chamber of the damper, a check valve is provided for the damper piston to flow hydraulic oil from the rod-side oil chamber to the rod-side oil chamber, and the oil reservoir side is provided at the bottom of the cylinder. A damping force-adjustable front fork, characterized in that a check valve is provided for flowing hydraulic oil from an oil chamber to a non-rod side oil chamber.