JPH0222510Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a compression side damping force adjustment device for a hydraulic shock absorber for a two-wheeled vehicle.

In double-tube hydraulic shock absorbers used in front forks of motorcycles, etc., the flow of hydraulic oil corresponding to the volume of entry into the inner tube that flows into the oil reservoir chamber during compression side operation is controlled, and the compression side damping force is adjusted according to the driving conditions. There are some that can be adjusted.

Conventionally, such a compression damping force adjusting device has been shown in FIG.

This double-tube hydraulic shock absorber 1 has an outer tube 2
An upper oil chamber A and a lower oil chamber B are defined by a piston section 5 provided at the tip of an inner tube 4 that penetrates into the outer tube 2 with a hollow rod 3 interposed therein. Room C is provided.

An orifice 6 is formed in the lower part of the hollow rod 3 to communicate the oil chamber B and the oil reservoir chamber C, and a compression side damping force adjustment device 9 is housed in parallel thereto.

This compression side damping force adjustment device 9 includes a valve body 8 that passes through the base portion of the outer tube 2 and the oil hole rod 10 and is screwed into the inner peripheral surface of the hollow rod 3. A cylinder part 11 is formed which opens into the cylinder part 11.
The oil reservoir chamber C and the oil chamber B communicate with each other through a port 12 formed in the valve body 8, an annular oil passage 13, and a port 14 formed in the hollow rod 3.

A substantially cylindrical valve 7 is slidably housed in the cylinder portion 11, and an annular valve seat 15 against which the valve 7 abuts is fixed.

Valve body 8 has valve 7 and valve seat 1
A return spring 16 is interposed to urge the return spring 16 in the direction of contacting the spring 5, and a spring seat 17 that supports one end of the spring 16 is screwed into the spring seat 17. The initial load of the spring 16 can be adjusted by rotating the spring seat 17 from the outside using a screwdriver or the like.

During low-speed operation on the pressure side stroke in which the inner tube 4 enters the outer tube 2, hydraulic oil corresponding to the volume of entry of the inner tube 4 passes through the orifice 6 and is stored in the oil reservoir chamber C.

FIG. 2 shows the relationship between the operating speed of this shock absorber 1 and the compression side damping force. Due to the flow path resistance of the orifice 6, in the low speed operating range, a damping force proportional to the square of the speed is obtained.

As the operating speed increases, the pressure in the lower oil chamber B upstream of the orifice 6 increases, and when this increased pressure received by the pressure receiving surface 18 exceeds the set load of the spring 16, the valve 7 opens while compressing it. The valve opening resistance generates a damping force that is primarily proportional to the operating speed.

The operating speed may further increase and the valve 7 may reach its maximum opening, but at this time the valve 7 acts as a fixed orifice, so the damping force is 2 times the speed.
It increases rapidly in proportion to the power of

Therefore, when the shock absorber 1 operates at a high speed exceeding a predetermined value, there is a problem in that the compression side damping force becomes too high suddenly and the feeling deteriorates.

The present invention was developed in view of the above problems, and an object of the present invention is to provide a compression side damping force adjusting device that can provide a stable damping force even during high-speed operation.

In this invention, a valve body is screwed onto the inner peripheral surface of a hollow rod from the bottom of a double-tube hydraulic shock absorber, and an annular valve seat is fixed inside this valve body, and this valve seat is attached around a main port that passes through the center. A cylindrical main relief valve that opens and closes the main port is provided with multiple sub-ports, and is brought into contact with one side of the valve seat via a return spring.The initial load of the return spring can be adjusted from the outside, while the sub-port opens and closes. An annular support relief valve is brought into contact with the valve seat from the side opposite to the main relief valve via a return spring.

Therefore, when the support relief valve in parallel with the main relief valve opens during high-speed operation of the shock absorber, it is possible to suppress a sudden increase in the compression side damping force, and stable damping force characteristics can be obtained from low speeds to high speeds.

Embodiments of the present invention will be described below based on the accompanying drawings. Note that the same reference numerals are given to the same components as in the conventional example.

As shown in FIG. 3, the valve body 8 is formed with a cylinder portion 11 that slidably accommodates the valve 7, and a valve seat 21 is press-fitted into the terminal end of the cylinder portion 11.

This annular valve seat 21 has a cylindrical rising portion 22 that extends to the vicinity where the port 12 opens, and a seat surface 23 on which the valve 7 comes into contact is formed at the tip, while a base portion 24 that fits into the valve body 8 has an outer periphery. A plurality of notches 25 are formed on the surface.

Here, the inside of the valve body 8 is the valve seat 2.
1 between the left oil chamber L and the right oil chamber R, the main port 27 is defined by the inner peripheral surface of the valve seat 26, the notch 25 and the inner peripheral surface of the valve body 8. The left and right oil chambers L and R communicate with a plurality of sub-ports 28 defined by.

An annular support relief valve 29 for opening and closing the sub-port 28 is provided, and a return spring 31 is interposed for bringing the valve 29 into contact with the end surface of the valve seat 21 on the side opposite to the main relief valve 7. One end of the return spring 31 contacts the valve 29, and the other end is supported by a spring seat portion 30 formed at the end of the valve body 8.

The approximately cylindrical main relief valve 7 that opens and closes the main port 27 is connected to the seat surface 2 as shown in FIG.
3 by a return spring 16.

A spring seat 17 supporting one end of the return spring 16 is screwed into the valve body 8, and a pin 33 is fixed to the base end of the spring seat 17. A plug 35 that engages with this pin 33 is rotatably housed within the valve body 8.
A hole 37 is formed on the inner circumferential surface of the valve body 8 that comes into sliding contact with the plug 35, and a ball 38 that engages with this hole 37 and a ball 38 are formed inside the plug 35.
A spring 39 is inserted to press and bias the plug 35 against the hole 37, thereby preventing the plug 35 from freely rotating.

When the shock absorber operates on the pressure side, in a region where the operating speed is low after the start of operation, the hydraulic oil corresponding to the volume that enters the inner tube passes from the oil chamber B to the oil reservoir chamber C through the orifice 6 formed in the hollow rod 3. 2 of the operating speed, similar to the conventional example described earlier.
A damping force proportional to the power is obtained.

As the pressure side operating speed of the inner tube increases, the pressure in the oil chamber B on the upstream side of the orifice 6 increases, and this increased pressure acting on the annular pressure receiving surface 18 of the main relief valve 7 opposes the spring 16. The valve 7 is biased in the opening direction. When this valve 7 begins to open, a damping force that is linearly proportional to the operating speed is obtained.

Furthermore, when the pressure-side operating speed of the inner tube increases and the pressure increases to such an extent that the main relief valve 7 reaches its maximum opening and proportional characteristics cannot be obtained,
The support relief valve 29 is also opened, and the hydraulic oil flows into the oil reservoir chamber C through both the main port 27 and the sub-port 25.

By opening the support relief valve 29, as shown by the two-dot chain line in FIG. Proportional damping force is obtained.

Also, when the plug 35 is rotated from the outside using a tool such as a screwdriver, the spring seat 17
can be screwed in the axial direction to change the initial load of the return spring 16.

Thereby, the set pressure of the main relief valve 7 can be adjusted, and the compression side damping force can be relatively strengthened or weakened or changed as shown in FIG.

Furthermore, when the set pressure of the main relief valve 7 is set higher than that of the support relief valve 29, as shown in FIG. The main relief valve 7 opens in this region.

In this way, by adjusting the initial load of the spring 16, the damping force in the high-speed operation range can be changed.

In addition, when the set pressures of the main relief valve 7 and the support relief valve 29 are made equal, the sixth
As shown by the solid line in the figure, a relatively high damping force can be set in the low speed range, and a flat damping characteristic with a small rate of change can be obtained over the entire range.

In summary, the present invention provides a main relief valve, and a sub-port parallel to the main port that penetrates through the center of the spring seat where the main relief valve opens and closes, and an annular sub-port that abuts the spring seat from the opposite side of the main relief valve. Since the support relief valve is provided, a stable damping force can be obtained even in the high-speed operation range, and by relatively changing the set pressure of each relief valve, various damping force characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing a conventional example;
The figure is a graph showing compression side damping force characteristics. FIG. 3 is a sectional view showing an embodiment of the present invention, and FIG.
FIG. 5 and FIG. 6 are graphs showing respective compression side damping force characteristics. 2...Outer tube, 3...Hollow rod,
7... Main relief valve, 8... Valve body, 16... Return spring, 17... Valve spring, 21... Valve seat, 27...
Main port, 28...Sub port, 29...Support relief valve, 31...Return spring, C...Oil sump chamber.

Claims (1)

[Scope of utility model registration request] In a double-tube hydraulic shock absorber with an oil reservoir inside a hollow rod, a valve body is housed at the bottom of the hollow rod, an annular valve seat is fixed inside the valve body, and a valve seat formed in the center of the valve seat is installed. A cylindrical main relief valve that opens and closes the main port is slidably housed inside the valve body, and a return spring that presses the main relief valve against the valve seat is interposed. A plurality of sub-ports are provided around the main relief valve, and an annular support relief valve for opening and closing the sub-ports is brought into pressure contact with the valve seat from the side facing the main relief valve via a return spring. Compression side damping force adjustment device for hydraulic shock absorbers.