JPH01190595A - Pressure side damping force adjustment mechanism for damper built-in type front fork - Google Patents

Abstract

PURPOSE:To make generated damping force to be automatically variable corresponding to load variation by forming the bypass passage of a pressure side hydraulic oil detouring the pressure side damping valve of a damper, and seriesly inserting a pressure sensing valve and orifice in the passage. CONSTITUTION:A cylinder 5 slidably housing a piston 4 engaged in an inner tube 2 is arranged to the center of an outer tube 1 in a front fork. The inside of the cylinder 5 is demarcated to two oil chambers A and B with the piston 4, and an extension side damping force generation valve 11, circulating a hydraulic oil between both chambers A and B, and a check valve 12 are provided to the piston 4. In this case, the hydraulic oil is made to flow out to an oil passage 6 from the chamber B via a main passage 9 in which a damping valve 8 is inserted, when the pressure side of the front fork operates. And a bypass passage 13 is formed in parallel to the passage 9, and an orifice 14 and a pressure sensing valve 5 closed by the pressure rise in the chamber B are seriesly inserted in the passage 13.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is a 70-ton 7-year-old motorcycle with a built-in damper that automatically changes the compression side damping force characteristics according to load changes.
4 Concerning general structure.

(Prior art) A front fork with a built-in damper has an i1! There are some with a rocky structure.

This is the 5 shilling that was used inside Outachie-11.
The main passage 9 of the pressure side hydraulic oil flowing out from the inside to the outside is composed of a plate valve 8A that serves as a pressure side damping valve that generates an infinitesimal force and is bent as the hydraulic oil pressure increases, and a cutout orifice 8B that allows the hydraulic oil to constantly flow out. A titted base valve 8 is installed, and a needle valve 30 is installed in the middle of a bypass passage 13 provided in parallel with the main passage 9 to change the oil passage cross-sectional area by external operation.

When the needle valve 30 is open, the pressure side hydraulic oil flows out from both the base valve 8 of the main passage 9 and the needle valve 30, so the damping force generated based on the outflow resistance is shown in the diagram m6 (
As shown in Figure 6 ( ), it increases gradually with the operating speed, but when the needle valve 30 is closed by external operation, the outflow path becomes only the main passage 9, so the generated reduction force increases as shown in Figure 6 (
1). Further, by operating the needle valve 30, the generated damping force can be varied steplessly by opening these valves.

(Problem to be solved by the invention) By the way, the opening degree of the needle valve 30 is 111! If the damping force characteristics are set to be optimal for normal driving, the damping force will tend to be insufficient during cornering and braking when the load on the front fork increases, and conversely, the damping force will be insufficient when cornering and braking, where the load on the front fork increases. If the force is set too high, the ride comfort during normal driving will be affected. Although it is possible to arbitrarily set the damping force characteristics in advance according to the driving conditions and the driver's preference, there is a 8! However, it was not possible to satisfy the required reduction force characteristics, which vary depending on the operating conditions.

The present invention has damping force adjustment 8! In order to solve the above problems of the structure, it is an object of the present invention to provide a damping force i111qw structure in which the generated damping force' automatically changes in response to changes in load.

(Means for Achieving the Object) The present invention provides a front fork with a built-in damper that includes gunbars inside an outer tube and an inner tube, and forms a bypass passage for pressure-side hydraulic oil by bypassing a pressure damping valve of the damper. A pressure-sensitive valve and an orifice, which close when the pressure of the hydraulic oil increases, are installed in series in this bypass passage.

(Function) Under normal conditions, the pressure-side hydraulic oil flows out from both the suppression damping valve and the bypass passage, but as the damper stroke increases, the gunbar internal pressure increases and the pressure-sensitive valve closes, causing the pressure-side hydraulic oil to flow out. Since this is performed only from the compression side damping valve, the generated damping force increases.

Therefore, during normal driving when the damper stroke is near neutral, a soft riding feel can be obtained, and during cornering and the like when the compression stroke amount increases, driving stability can be improved by the damping force.

(Example) Embodiments of the present invention are shown in FIGS. 1 to 4.

In FIG. 1, reference numeral 1 denotes a front fork tube 7 containing hydraulic oil, into which an inner tube 2 is slidably inserted from a tip opening shown in FIG. A piston 4 is supported at the center of the inner tube 2 via a piston loft 3 of a built-in damper, and a sill 5 for housing the piston 4 in a freely sliding manner is erected at the center of the inner tube 1.

In addition, the tip of the inner tube 2 opens toward a passage 6 with an annular cross section formed between the outer tube 1 and the sill 5, and the upper part of the inner tube 2 has an internal volume that 7 An oil sump chamber C is provided which is filled with gas to compensate for changes. Note that 26 is a suspension spring that urges the outer tube 1 and the inner tube 2 in the repulsion direction.

The inside of the cylinder 5 is defined by the piston 4 into an oil chamber A on the tip side and an oil chamber [3 on the base side. 12 are provided.

A hollow center rod 7 that stands upright at the bottom of the sill 5 protrudes into the oil chamber I3, and when the inner tube 2 enters the outer tube 1 (compression side operation), the hydraulic oil in the sill 5 is transferred from the oil chamber B to the oil passage. 6 is formed through the outside of this center rod 7. In the middle of the main passage 9, a base valve 8 similar to the conventional example is installed to resist the flow of pressure 1)11 hydraulic oil. In addition, 1
0 is expansion side operation 11, ? Ijll < check valve.

On the other hand, a bypass passage 13 is formed in parallel with the main passage 9 through the inside of the center rod 7, through which the pressure side hydraulic oil also flows out from the oil chamber B to the oil passage 6. This bypass passage 13 has an orifice 14 formed in the center rod 7.
After passing through the pressure sensitive valve 15 provided downstream,
It opens inside an oil hole frame 25 provided at the base end of the outer tube 1 so as to surround the base end of the sill 5.

As shown in FIG. 1, the pressure sensitive valve 15 includes a spool 17 that is housed in the base end of the spool 1 so as to be freely slidable in a right angle direction, and a valve body 17A1 formed on the outer circumference of the spool 17.
It consists of a valve seat 19 formed opposite to the rear of the spool 17, a pressure detection spring 21 that urges the spool 17 toward the 111g valve, and a stopper 20 that supports the pressure detection spring 21. It is guided along the outer periphery, passes between the valve body 17A and the valve seat 19, and reaches the inside of the oil hole frame 25. Note that the rear end of the spool 17 is open to the atmosphere, and the stopper 20 is fixed to the outer tube 1.

Next, the effect will be explained.

When operating on the pressure side, the inner tube 2 enters the inner tube 1 and the piston 4 enters the sill 5, respectively. Accordingly, the hydraulic oil in the oil chamber B flows from the valve 12 into the oil chamber A, and the hydraulic oil corresponding to the intrusion volume of the piston rod 3 flows through the oil passage 6 outside the cylinder 5 into the inner tube 2.
The oil flows out into the oil sump chamber C inside the tank.

At this time, there are two flow paths for the hydraulic oil from the oil chamber B to the oil passage 6: the main passage 9 and the bypass passage 13, and when the pressure sensitive valve 15 of the bypass passage 13 is open, the generated reducing force is As shown in FIG. 3(a), the characteristics defined by the base valve 8 are weakened by the bypass portion through the orifice 14, showing a gradual increasing characteristic, whereas when the pressure sensitive valve 15 is closed, the characteristic as shown in FIG. As shown in b), the compression side crushing force characteristic has a larger increase rate than that specified only for the base valve 8.

These two types of pressure side depletion force characteristics automatically change according to the pressure in the oil chamber 13, that is, the pressure in the oil reservoir chamber C.

When the pressure in the oil chamber B increases, the hydraulic pressure acting on the tip of the spool 17 increases, and the spool 17 eventually retreats against the pressure detection spring 21. As a result, the valve body 17A is seated on the valve seat 19, and the oil passage 13 is closed. The pressure of the hydraulic oil changes according to the expansion and contraction stroke of the damper, and therefore the compression damping force automatically increases when the front fork contracts to a certain position (Sl) as shown in Figure 4. It shows position-dependent neutrality.

For this reason, for example, if the load increases temporarily due to cornering or nose dive while driving, the compression side y-force will automatically increase in response to the increased load, which will not impede normal ride comfort. The vehicle runs stably.

In addition, without fixing the stopper 20 to the tube 1,
If it is screwed into the tube 1 so that it can move forward and backward by external operation, the setting of the spring load of the pressure detection spring 21 can be changed to adjust the closing timing of the valve 15. 4 adjustments can be made.

In the expansion side operation, the hydraulic oil in the oil passage 6 flows back to the oil chamber B from the check valve 10 without resistance, and the hydraulic oil in the oil chamber A returns to the valve 1.
1 and flows into the oil chamber B while generating a rebound damping force. Note that the pressure sensitive valve 15, which had been closed, opens due to the pressure drop in the oil chamber B and the repulsive force of the pressure detection spring 21.

(Effects of the Invention) As described above, the present invention includes a pressure-sensitive valve that closes when the pressure inside the damper increases in the pressure-side hydraulic oil bypass passage formed by bypassing the pressure-side damping valve. When deflated, a pressure-sensitive valve closes;
Subsequent annihilation power increases. For this reason, while maintaining a soft ride during normal driving when the damper stroke is near neutral, the compression side damping force is increased in response to centrifugal force during cornering and nose dive due to braking, improving the sense of stability of the vehicle body. It has a great effect on improvement.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the base end of a front oak showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of the front fork,
3 and 4 are graphs showing damping force characteristics. Further, FIG. 5 is a cross-sectional view of the base end of a front fork showing a conventional example, and FIG. 6 is a graph similarly showing damping force characteristics. 1... Outer tube, 2... Inner tube, 3
... Piston rod, 4... Piston, 5... Schilling, 8... Base valve, 8A... Plate valve,
8B...Notch orifice, 9...Main passage, 13
... Bypass passage, 14... Orifice, 15...
・Pressure sensitive valve.

Claims (1)

[Claims] In a front fork with a built-in damper that has a damper inside the outer tube and inner tube, a bypass passage for the pressure side hydraulic oil is formed by bypassing the damper's pressure side damping valve, and this bypass passage is closed by an increase in the pressure of the hydraulic oil. A pressure-side damping force adjustment mechanism for a front fork with a built-in damper that features a pressure-sensitive valve and an orifice installed in series.