JP2606837B2 - Front fork - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a front fork capable of adjusting both a generated damping force on an extension side and a generated damping force on a compression side.

(Prior Art) As a front fork of a motorcycle, there have been proposed various types of front forks capable of adjusting a damping force to an optimum state in accordance with driving conditions.

For example, JP-A-59-3409 discloses a stroke position-dependent damping force adjusting device in which a position detecting spring is arranged in series with a suspension spring, and a compression damping force is changed according to the amount of deflection of the detecting spring. Is disclosed.

According to this, as the stroke amount increases, the damping force automatically increases, so that a soft riding comfort can be exhibited at normal times, and running stability can be maintained by the high damping force when the vehicle greatly vibrates.

Also, select the orifice interposed in the passage through which the hydraulic oil passes during extension operation so that the extension side damping force of the front fork can be adjusted arbitrarily from the outside, and adjust the extension damping force according to the orifice area. A damping force adjusting device capable of increasing or decreasing the pressure is disclosed in Japanese Utility Model Laid-Open No. 57-174190.

(Problems to be Solved by the Invention) However, each of these devices has a damping force adjusting device mounted alone, and none has a damping force characteristic combining both functions.

This is because the mechanism for adjusting the damping force is located in the central part inside the front fork, so combining both functions complicates the structure and hinders the flow of hydraulic oil, or expands the front fork This is because there is a problem that the user has to do so.

Therefore, an object of the present invention is to provide a front fork provided with a damping force adjusting device that can be installed in a small space inside the front fork and has both a function of adjusting the extension-side and compression-side damping forces.

(Means for Solving the Problems) In the present invention, the inner tube is slidably inserted into the outer tube, and the lower end of the cylinder that slides on the inner periphery of the inner tube is concentrically fixed to the outer tube. The piston provided at the tip of the inner tube defines an upper oil chamber and a lower oil chamber between the cylinder and the inner tube and between the cylinder and the outer tube. In a front fork having an oil reservoir communicating with the lower oil chamber, a rotary valve for adjusting a communication area between the upper oil chamber and the cylinder internal passage is rotatably arranged on the inner periphery of the upper end of the cylinder, and the rotary valve is rotated. The operation rod with the stepped bolt inserted from the top of the inner tube can slide freely with each other and cannot rotate relative to each other. On the other hand, a spring holder is arranged between the suspension spring and the position detection spring interposed in series between the cylinder and the inner tube, and the stepped bolt slidably penetrates the spring holder, A sleeve is disposed between the position detection spring and the cylinder, and a spool that forms a variable passage for the hydraulic oil flowing out of the cylinder internal passage into the oil reservoir chamber between the sleeve and the stepped bolt is provided. The spool is movably inserted and urges the spool in a direction of decreasing its effective passage area via a spring whose one end is supported by the spring holder.

(Operation) Therefore, when the front fork is operated on the pressure side, the operating oil corresponding to the volume of the inner tube that has flowed out flows into the oil reservoir through the variable passage of the spool, and a pressure-side damping force is generated by the resistance at this time.

Since the position of the spool is displaced in accordance with the amount of compression of the suspension spring to narrow the pressure-side passage, the generated damping force increases as the amount of approach stroke of the inner tube increases.

On the other hand, at the time of the extension side operation, the hydraulic oil in the upper oil chamber flows into the cylinder internal passage via the rotary valve, and at this time, the extension side damping force is generated according to the opening degree of the rotary valve.

The rotary valve rotates via an operation rod and a stepped bolt operated from the outside, and can adjust a damping force according to a passage area selected by a rotation position.

(Example) An example of the present invention will be described with reference to the drawings.

The inner tube 2 is slidably inserted into the outer tube 1. The lower end of the cylinder 3 is concentrically fixed inside the outer tube 1.

An upper oil chamber 5 is provided between the inner circumference of the inner tube 2 and the outer circumference of the cylinder 3 by the piston 4 at the tip of the inner tube 2, and a lower oil chamber 6 is provided between the outer circumference of the cylinder 3 and the inner circumference of the outer tube 1. Is partitioned.

An oil reservoir 7 is formed in the upper part of the inner tube 2,
The oil reservoir 7 communicates with the lower oil chamber 6 via an internal passage 8 of the cylinder 3.

An enlarged diameter portion 10 is formed at the upper end of the cylinder 3, and a cylindrical rotary valve 11 is rotatably arranged on the inner periphery of the enlarged diameter portion 10.

The rotary valve 11 has a passage 9 passing therethrough in the axial direction, and a plurality of orifices 12 having different opening degrees are formed on a peripheral wall thereof.
A, 12B ... are formed, and these orifices 12A ...
0, the upper oil chamber 5 and the internal passage 8 communicate with a predetermined opening area,
This generates a damping force at the time of the extension side operation.

In the rotary valve 11, the orifices 12A, 12B...

At the center of the rotary valve 11, a deformed engaging portion (notched circular section) 16 of a stepped bolt 15 is slidably inserted.
Orifice 12A of rotary valve 11 depending on the rotation position of 15
... is selected.

A long cylindrical holder 17 is screwed to the upper part of the stepped bolt 15 and is connected by a pin 18.

On the upper part of the holder 17, an odd-shaped engagement portion 20 of the operation rod 19 is provided.
Although they cannot be rotated relative to each other, they are slidably inserted, and when the operation rod 19 is rotated, the stepped bolt 15 rotates.

The upper end of the operating rod 19 air-tightly penetrates a cap 22 that closes the upper end of the inner tube 2, and an adjustment dial 23 is attached to the shaft end.

Therefore, when the dial 23 is rotated, the operation rod
19, holder 17, rotary valve 11 via stepped bolt 15
Are rotated, and the orifices 12A ... communicating with the passage 13 are selected, whereby the extension-side damping force can be adjusted.

A suspension spring between the inner tube 2 and the cylinder 3
24 and a position detection spring 25 are arranged in series. In this case, a cylindrical spring holder 26 with a flange is interposed between the suspension spring 24 and the position detection spring 25, and a cylindrical sleeve 28 is provided between the lower end of the position detection spring 25 and the cylinder 3. Interposed.

Accordingly, when the inner tube 2 enters while compressing the suspension spring 24, the position detection spring 25 is also compressed in proportion to the intrusion stroke.

A check valve 29 that opens when the extension side is operated is arranged on the inner periphery of the sleeve 28.

A spool 30 is inserted into the stepped bolt 15, and a spring 31 for urging the spool 30 toward the stepped portion of the bolt.
Is locked to the inner peripheral flange 32 of the spring holder 26.

A cutout groove 33 whose sectional area changes in a tapered shape extending in the axial direction is formed on the outer periphery of the spool 30, and the cutout groove 33 is inserted into the sleeve 28.

When the position detection spring 25 is compressed, the spool 30 advances toward the sleeve 28 together with the stepped bolt 15, and the passage area formed by the cutout groove 33 decreases according to the advance position of the spool 30, The compression damping force is increased.

By the way, the position detecting spring 25 interposed between the spring holder 26 and the sleeve 28 is housed in a cylindrical spring stopper 34 having a through hole 36 in the outer peripheral portion, and the maximum length is regulated.

For this reason, the front fork extends completely and the suspension spring 24
Even when the load of the spring becomes minimum, the length of the position detecting spring 25 does not extend beyond the value regulated by the spring stopper 34, and therefore, the spring holder 26 and the stepped bolt
A predetermined gap is always maintained between the holder 17 and the holder 17 connected to the step 15, and the rotation of the stepped bolt 15 can be smoothly performed without receiving a spring load.

The piston 4 at the tip of the inner tube 2 is provided with a check valve 35 that opens when the pressure side is actuated, and allows hydraulic oil to flow from the lower oil chamber 6 into the upper oil chamber 5 without resistance.

 The configuration is as described above. Next, the operation will be described.

At the time of the pressure side operation in which the inner tube 2 enters the outer tube 1, a part of the operating oil in the lower oil chamber 6 flows into the upper oil chamber 5, and the operating oil corresponding to the integral volume of the inner tube 2 enters, It flows out into the upper oil reservoir 7 via the internal passage 8 of the cylinder 3.

During this outflow process, the pressure side hydraulic oil is
When passing through the notch groove 33 of the spool 30 from the passage 9 of 11,
The passage resistance is received according to the opening area.

Front fork load is suspension spring 24 and position detection spring
The suspension spring 24 and the position detecting spring 25 are compressed in accordance with the amount of the inner tube 2 entering.

The spring holder 26 moves with the compression of the position detection spring 25, and compresses the spring 31.

Therefore, the spool 30 is pushed by the spring 31 and enters the inside of the sleeve 28 integrally with the stepped bolt 15.

The passage formed by the sleeve 28 and the notch groove 33 is narrowed by the entry of the spool 30, and the passage resistance to the flow of the pressure-side hydraulic oil gradually increases.

Therefore, the generated damping force at the time of the compression side operation varies depending on the position of the approaching stroke of the inner tube 2, and the greater the amount of approach, the stronger the damping force.

In this manner, the damping force characteristic depending on the stroke position can be exhibited, and when the average stroke position of the inner tube 2 is near neutral, such as when traveling on a flat road,
On the other hand, when the vehicle travels on a rough road where the stroke amount is large, a high damping force is generated in a region where the pressure side operation amount of the inner tube 2 is large, thereby preventing bottom bumps and the like.

Since the spool 30 is urged by the spring 31, when the pressure generated upstream of the spool 30 exceeds the set load of the spring 31, the spool 30 is pushed up, so that the spool 30 is pushed up from the road surface during the pressure side operation. For example, when a shock is applied, the high pressure can be absorbed so that the impact is not transmitted to the vehicle body side.

Next, when the inner tube 2 moves out of the outer tube 1 to the extension side operation, the hydraulic oil from the upper oil chamber 5 that contracts flows from the passage 13 through the orifice 12 of the rotary valve 11.
It passes through A and flows out into the internal passage 8 of the cylinder 3.

When this hydraulic oil passes through the orifice 12A, it receives resistance, and this becomes the extension side damping force.

The opening of the rotary valve 11, that is, the area of the orifice 12A, can be freely selected by rotating the rotary valve 11, and the generated damping force increases as the valve opening decreases.

In order to adjust the opening of the rotary valve 11, the dial 23 is rotated to rotate the rotary valve 11 via the operating rod 19, the holder 17, and the stepped bolt 15, and the orifices 12A, 12B... Select as appropriate.

In this manner, the driver can freely adjust the extension-side damping force according to running conditions and the like.

While the rotary valve 11 is mounted on the upper end of the cylinder 3, the dial 23 and the operating rod 19 are mounted on the inner tube 2 side and relatively displaced, but the stepped bolt 15 is attached to the holder 17 and the rotary valve 11. Since these members are slidably fitted to each other with a different diameter, these relative displacements in the axial direction can be absorbed.

The position detection spring 25 interposed between the suspension spring 24 and the cylinder 3 is stopped by the rotary valve since the maximum amount of extension is regulated by the spring stopper 34.
When adjusting the position 11, even if the load of the suspension spring 24 is small, the position detecting spring 25 does not push up the spring holder 26 more than necessary.
A predetermined gap is always formed between the upper surface of the stepped bolt and the lower surface of the holder 17 connected to the stepped bolt 15, so that the friction by the spring 25 does not work and the stepped bolt 15 can rotate smoothly.

The hydraulic oil that has passed through the orifice 12A of the rotary valve 11 compensates for the volume of the inner tube 2 that has escaped.
Flows into.

At this time, most of the hydraulic oil from the oil reservoir 7 can flow smoothly through the check valve 29 because the pressure downstream of the notch groove 33 of the spool 30 is reduced and the check valve 29 is opened. .

(Effects of the Invention) As described above, according to the present invention, it is possible to control the compression-side damping force in a position-dependent manner and to adjust the extension-side damping force by an external operation, and to set the optimum damping force characteristics according to the operating conditions. can do.

In addition, a mechanism for generating a compression side damping force is provided above the rotary valve that generates the extension side damping force, and a stepped bolt for rotating the rotary valve is disposed so as to penetrate the spool for generating the compression side damping force. Therefore, the two damping force generating mechanisms can be installed in a narrow space above the cylinder while securing the flow path of the hydraulic oil.

[Brief description of the drawings]

The drawings are sectional views showing an embodiment of the present invention. 1 ... outer tube, 2 ... inner tube, 3
... cylinder, 5 ... upper oil chamber, 6 ... lower oil chamber, 7 ...
... oil reservoir, 8 ... internal passage, 11 ... rotary valve, 15
…… stepped bolt, 17… holder, 19 …… operation rod, 24
... suspension spring, 25 ... position detection spring, 26 ... spring holder, 30 ... spool, 31 ... spring.

Claims (1)

(57) [Claims] An inner tube is slidably inserted into an outer tube, a lower end of a cylinder slidingly in contact with an inner periphery of the inner tube is fixed concentrically to the outer tube, and a piston provided at a tip of the inner tube. Thereby, an upper oil chamber and a lower oil chamber are defined between the cylinder and the inner tube and between the cylinder and the outer tube, and an oil reservoir communicating with the lower oil chamber via an internal passage of the cylinder is provided above the inner tube. In the formed front fork, a rotary valve that adjusts the communication area between the upper oil chamber and the cylinder internal passage is rotatably arranged on the inner periphery of the upper end of the cylinder, and a stepped bolt that rotates the rotary valve is inserted from the top of the inner tube. While being slidably and relatively non-rotatable with each other,
A spring holder is arranged between the suspension spring and the position detection spring interposed in series between the cylinder and the inner tube, and the stepped bolt slidably penetrates the spring holder, and the position detection spring and A sleeve is arranged between the cylinder and the stepped bolt, and a spool forming a variable passage of hydraulic oil flowing out of the cylinder internal passage to the oil reservoir between the sleeve and the sleeve is slidably inserted into the stepped bolt. A front fork, wherein a spool is urged in a direction of decreasing an effective passage area thereof via a spring whose one end is supported by the spring holder.