JPH0224989Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement of a front fork in a two-wheeled vehicle that can adjust the expansion damping force.

(Prior Art) An anti-nose dive mechanism is known as a mechanism for preventing front wheels from sinking during braking.

This is designed to prevent the front forks from contracting by providing a valve that closes the pressure-side hydraulic fluid flow path of the front fork during braking.

A front fork equipped with such an anti-nose dive valve and whose rebound damping force can be adjusted from the outside was proposed by the present applicant in Japanese Patent Application No. 1983-
It was proposed as No. 227698, and this is now the fifth issue.
This will be explained based on FIG.

1 is an outer tube, 2 is an inner tube, 3 is a cylinder fixed to the outer tube 1, and 4 is a check valve attached to the inner tube, which define upper and lower oil chambers A, B and an oil reservoir chamber C. There is.

The oil chamber B and the oil reservoir chamber C communicate from an oil passage 5 at the bottom of the outer tube 1 through the inside of the cylinder 3, and an anti-nose dive valve 6 is interposed in the middle of the oil passage 5, and this valve 6 is used for braking. The oil passage 5 is closed in conjunction with the action, and the oil passage 5 is closed at other times.
is open.

The oil chamber A communicates with an oil reservoir chamber C via an orifice 7 at the upper end of the cylinder 3, and a rotary valve 8 is provided to adjust the opening area of the orifice 7.

The rotary valve 8 is rotatably locked to a control rod 9 disposed coaxially with the inner tube 2, but is slidably connected in the axial direction.

When the rotary valve 8 is rotated, the effective area of the orifice 7 is finely adjusted depending on the amount of overlap with the valve opening. Therefore, the resistance given to the hydraulic oil flowing out from the oil chamber A to the oil reservoir chamber C through the orifice 7, which contracts during the extension-side operation, changes, and the extension-side damping force can be freely adjusted.

On the other hand, during pressure side operation, part of the hydraulic oil in the oil chamber B flows into the oil chamber A through the check valve 4, but the intrusion volume of the inner tube 2 is absorbed into the oil passage 5.
The oil flows from there through the inside of the cylinder 3 to the oil reservoir chamber C, and in this pressure side stroke, no particular damping force is generated, and the impact input is smoothly absorbed.

By the way, when braking, anti-nose dive valve 6
For example, if it closes in conjunction with the brake wire,
The hydraulic oil in the oil chamber B cannot escape to the cylinder 3 side, but when the inner tube 2 tries to sink, the check valve 4 opens, so the hydraulic oil in the oil chamber A
The oil flows out through the orifice 7 into the oil sump chamber C, making the anti-nose dive mechanism less effective.

Therefore, when the anti-nose dive valve 6 is closed, the rotary valve 8 is slid upward so as to close the orifice 7.

For this purpose, a pipe 10 is disposed coaxially on the inner circumference of the cylinder 3, a passage 12 is provided that communicates an annular gap 11 between the pipe 10 and the cylinder 3 with the oil chamber B, and an upper opening of this gap 11 is provided. is fixed ring 1
3 to seal.

A piston 14 connected to a stopper ring 15 is slidably fitted into a hole communicating with the gap 11 in the fixing ring 13, and the piston 14 is pushed up according to the hydraulic pressure generated in the gap 11.

The stopper ring 15 receives the rotary valve 8 which is urged downward via a spring 16, and normally the rotary valve 8 is pushed downwardly as shown in the figure.
is supported, and in this state open the opening 8 of the rotary valve 8.
The amount of overlap between a and the orifice 7 is adjusted to a predetermined value.

When the anti-nose dive valve 6 closes during braking, the inner tube 2 enters the oil chambers A and B.
The hydraulic oil tends to flow out into the oil reservoir chamber C only through the orifice 7, and at this time, the pressure in the oil chambers A and B increases according to the orifice restriction.

This pressure acts on the piston 14 from the opening 12 through the gap 11, and when it overcomes the acting force of the spring 16, the rotary valve 8 is pushed upward via the stop ring 15 and closes the orifice 7.

As a result, the outflow of the hydraulic oil from the oil chambers A and B is completely stopped, and thereafter, the intrusion of the inner tube 2 is stopped.

In this way, the anti-nose dive function is secured, and when the operation is performed to the extension side immediately after this, the pressure decreases as the oil chamber B expands, but due to the resistance in the gap 11, the piston 14 does not fall immediately, and therefore the lowering of the rotary valve 8 is delayed, and by delaying the opening of the orifice 7, the damping force immediately after the transition to the expansion side can be increased.

(Problem to be solved by the invention) However, when the pipe 10 is arranged inside the cylinder 3 in this way, the effective cross section of the cylinder internal passage becomes small, and as the inner tube 2 expands and contracts, the pipe 10 passes through the cylinder. Since the flow velocity of the hydraulic oil increases accordingly, cavitation is likely to occur and the generation of damping force becomes unstable.

Additionally, since the rise of the anti-nose dive changes depending on the internal pressure generated by the opening area of the orifice 7 when the mechanism is activated, the start of the anti-nose dive's effectiveness varies depending on the opening degree of the orifice 7. It was hot.

In other words, it is preferable that the effectiveness of the anti-nose dive and the rebound damping force be made independent of each other.

The present invention aims to solve such problems.

(Means for Solving the Problem) The present invention has an inner tube slidably inserted into an outer tube, a cylinder located inside the inner tube, and a check valve provided at the tip of the inner tube. An upper oil chamber and a lower oil chamber are defined through the oil chamber, and an oil reservoir chamber is formed.
An anti-bird dive valve is installed in the middle of the passage that communicates the lower oil chamber and the oil reservoir chamber, while a rotary valve is placed on the inner circumference of the orifice formed in the cylinder to communicate the upper oil chamber and the oil reservoir chamber. In the front fork, the rotary valve is configured to be rotatable via a rod coaxially provided in the inner tube, and the rebound damping force can be adjusted based on the degree of communication opening between the rotary valve and the orifice. A sleeve is placed on the inner periphery of the rotary valve so that it can slide freely, and two check valves are provided that lock onto protrusions provided on the inside of the sleeve and open oppositely and in different directions. Each valve is energized by a spring so as to close each other at the locked position and cut off communication between the inside of the cylinder and the oil reservoir chamber, while a through hole communicating with the orifice and the opening of the rotary valve is provided in the sleeve. and the through hole is provided at a position that constantly communicates with the internal passage of the cylinder across the check valve.

(Function) Therefore, hydraulic oil is sucked from the cylinder internal passage into the lower oil chamber which expands during expansion side operation, and one check valve opens to allow oil from the oil reservoir chamber to flow into the upper oil chamber. The hydraulic oil flows into the cylinder internal passage through the orifice, rotary valve opening, and through hole, generating a predetermined damping force.

During pressure side operation, part of the hydraulic oil in the lower oil chamber flows into the upper oil chamber, and the rest flows out from the cylinder internal passage into the oil reservoir chamber by opening the other check valve with almost no resistance.

On the other hand, when the anti-nose dive valve closes during braking, the hydraulic oil in the upper and lower oil chambers flows into the cylinder internal passage through the orifice, but this increases the pressure in the internal passage and causes the sleeve to rise together with the check valve. to shut off the rotary valve opening.

Therefore, the upper and lower oil chambers are disconnected from the oil reservoir chamber, and the invasion of the inner tube is stopped.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

Rotary valve 8 located on the inner circumference of cylinder 3
rotates together with the control rod 9, but is held against a step 20 formed on the inner periphery of the cylinder 3 by a retaining pin (c-pin) 21 to prevent it from moving in the axial direction. .

In addition, 22 is the cylinder 3 and the inner tube 2.
Below the ring 23, which seals the sliding surface of the cylinder 3, is an elastic ring that is fitted into the cylinder 3, and a force acting in the direction of contraction is always acting on the ring 23, which presses the ball 26 fitted into the hole 25 of the cylinder 3 from the outside. The rotary valve 8 is brought into contact with the outer periphery of the rotary valve 8, and the rotary valve 8 is elastically fixed and held at the position where rotation is stopped.

The rotary valve 8 has an outer cylindrical portion 27 supported by a stay 28 extending in the radial direction, and the control rod 9 is inserted into the center boss portion 29 of the stay 28.
Rotation of the rod 9 causes the rotary valve 8 to rotate.

A valve opening 8a is formed in the outer cylindrical portion 27, and a sleeve 30 is slidably disposed on the inner periphery of the valve opening 8a.

The sleeve 30 slides between a step 32 and a stopper 31 fitted to the lower end of the rotary valve.

A through hole 33 communicating with the orifice 7 is formed in the sleeve 30, and an annular protrusion 34 is provided on the inner periphery of the sleeve 30. Check valves 36 with different opening directions are provided on both sides of the protrusion 34. 37 is locked.

The upper check valve 36 is connected to the internal passage 38 of the cylinder 3.
The lower check valve 37 only allows flow from the oil reservoir chamber C to the internal passage 38.

The upper check valve 36 includes a flange-shaped valve plate 41 whose inner circumference slides against a cylindrical valve guide 40 disposed on the outer circumference of the rod 9, and the valve guide 40 and the valve plate 4.
1, and the valve plate 41 contacts and seats on the other check valve 37 to close the valve.

A through hole 43 is formed in the inner periphery of the valve plate 41, and communicates the internal passage 38 with the oil reservoir chamber C when the valve plate 44 of the lower check valve 37 is lowered.

The valve plate 44 of the lower check valve 37 is biased by a spring 45 so that the outer periphery of the valve plate 44 comes into sliding contact with the sleeve 30 and is engaged with the protrusion 34 .

The spring 42 is set to have a stronger spring load than the spring 45, and with the valve plates 44 and 45 in contact with each other, the sleeve 30 is moved to the lower stopper 31.
It is moved to the lower position until it is locked.

In this state, the orifice 7, the valve opening 8a, and the through hole 33 communicate with each other, and the hydraulic oil in the oil chamber A is transferred to the check valve 36,
37 into an internal passageway 38 below.

However, when the sleeve 30 moves upward, the through hole 33 disengages from the valve opening 8a, cutting off communication.

The device is configured as described above, and its operation will be explained next.

During pressure side operation when the inner tube 2 enters, a portion of the hydraulic oil from the contracting oil chamber B flows into the upper oil chamber A, and the remaining surplus oil flows out from the oil passage 5 to the cylinder internal passage 38. However, due to this flow, the check valves 36 and 37 are pushed up together, and rise together with the sleeve 30 until they come into contact with the stepped portion 32. When the sleeve 30 is locked to the stepped portion 32, the lower check valve 37 remains locked and only the upper check valve 36 opens while compressing the spring 42, causing the cylinder to open. The hydraulic oil in the internal passage 38 is allowed to flow out into the oil reservoir chamber C with almost no resistance.

On the other hand, during the expansion side operation, the hydraulic oil from the cylinder internal passage 38 is sucked into the expanding lower oil chamber B through the oil passage 5, while from the contracting upper oil chamber A, the orifice 7, the valve opening 8a, The hydraulic oil flows out into the internal passage 38 through the through hole 33, but the pressure in the internal passage 38 becomes low due to the shortage corresponding to the volume extracted from the inner tube 2. 45, and at this time, since the sleeve 30 is also stationary in the lower position, the upper check valve 36 also remains in that position, and eventually passes through the gap created between the valve plates 44 and 41. As a result, the hydraulic oil flows from the oil reservoir chamber C to the internal passage 38 side with almost no resistance.

Therefore, the hydraulic oil is smoothly sucked into the lower oil chamber B, and a predetermined rebound damping force is generated based on the resistance of the hydraulic oil flowing out from the upper oil chamber A through the orifice 7.

In this case, by rotating the rotary valve 8 and increasing or decreasing the amount of overlap between the valve opening 8a and the orifice 7, the effective area of the orifice can be freely adjusted. It can be set freely depending on the rotation angle.

On the other hand, when the anti-nose dive valve 6 closes and blocks the oil passage 5 during braking, the front fork tends to sink due to the forward movement of the center of gravity of the vehicle due to braking. The hydraulic oil in the lower oil chamber B only flows into the upper oil chamber A through the check valve 4, and eventually flows through the orifice 7 and attempts to flow out into the internal passage 38. This spilled oil increases the pressure in the internal passage 38, pushing up the upper and lower check valves 36 and 37 together with the sleeve 30, as in the case of the pressure side operation.

However, as the sleeve 30 rises, the through hole 33
Since the communication between the valve opening 8a and the valve opening 8a is cut off before contacting the stepped portion 32, the flow of hydraulic oil from the oil chamber A is stopped without the need for the check valve 36 to open.

In this way, when the flow of hydraulic oil to the oil reservoir chamber C side is stopped, the inner tube 2 cannot enter any further, and the front fork is prevented from sinking.

In this case, the sleeve 30 closes the valve opening 8a when the hydraulic oil flowing out from the orifice 7 reaches a certain amount at the beginning of braking, so the anti-nose dive effect is effective regardless of the effective area of the orifice 7. The situation will always be the same.

(Effect of the invention) As described above, according to the invention, a constant and stable anti-nose dive function can always be exhibited regardless of the adjustment of the rebound damping force.

The rebound damping force can be adjusted independently and freely, and the sleeve narrows down the effective area of the orifice and fully closes the orifice for the rebound operation immediately after the anti-nose dive operation, so the rebound damping force is adjusted freely. It can also increase your power.

In addition, the structure is simpler than that of the conventional one, and in particular, by pre-installing a check valve and a sleeve inside the rotary valve, productivity during assembly is improved and the weight is also reduced.

Note that the effective cross-sectional area of the internal passage of the cylinder can be expanded due to the lack of a conventional pipe, which has the effect of reducing cavitation and aeration during suction.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the main parts of the embodiment of the present invention, Figure 2
Figure 3 is a cross-sectional view along the X and Y arrows in Figure 1, Figure 4 is a cross-sectional view along the Z arrow, Figure 5 is a vertical cross-sectional view of the conventional example, and Figure 6 is a cross-sectional view of its main parts. It is a diagram. 1... Outer tube, 2... Inner tube, 3... Cylinder, 4... Check valve, 5... Oil passage, 6... Anti-nose dive valve, 7...
Orifice, 8... Rotary valve, 8a... Valve opening, 9... Rod, 30... Sleeve, 3
1...Stopper, 32...Step part, 33...Through hole,
34...Protrusion, 36, 37...Check valve, 38...
Internal passage, 41, 44... Valve plate, 42, 45...
spring.

Claims (1)

[Scope of utility model registration request] An inner tube is slidably inserted into the outer tube, and a cylinder is arranged inside the inner tube, and an upper oil chamber and a lower oil chamber are defined through a check valve provided at the tip of the inner tube. An anti-nose dive valve is installed in the middle of the passage that communicates the lower oil chamber and the oil reservoir chamber, and an orifice is formed in the cylinder to communicate the upper oil chamber and the oil reservoir chamber. A rotary valve is arranged on the inner circumference of the inner tube, and this rotary valve is configured to be rotatable via a rod coaxially installed in the inner tube, and the rebound damping force is generated based on the degree of communication opening between the rotary valve and the orifice. In the adjustable front fork, a sleeve is placed in sliding contact with the inner circumference of the rotary valve,
Two check valves are provided that lock onto protrusions provided inside the sleeve and open oppositely and in different directions,
The check valves are each energized by a spring so as to close each other at the locked position and cut off communication between the inside of the cylinder and the oil reservoir chamber, while the through hole that communicates with the orifice and the opening of the rotary valve is biased by a spring. is provided in the sleeve, and the through hole is provided in a position that constantly communicates with the internal passage of the cylinder across the check valve.