JPS6236715Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hydraulic shock absorber suitable for use in front forks of two-wheeled vehicles.

Generally, a front fork is installed between the front body of a motorcycle or other vehicle and the wheels to absorb and reduce shock from the wheel side.Furthermore, in order to improve riding comfort, a front fork is installed between the front body of a motorcycle, etc. and the wheels, and is a position-dependent type that changes the damping force depending on the position of the piston to improve riding comfort. The front fork is known.

For example, there is a position-dependent front fork of this type disclosed in Japanese Utility Model Application Publication No. 1757-1757, but in such a front fork, the flow velocity in the cylinder increases and the hydraulic oil in the upper liquid chamber passes through the hollow cylinder. The air in the air chamber is drawn into the hollow cylinder as the liquid rapidly flows out into the lower liquid chamber.
When the inner tube hole passes through the piston part provided on the outer periphery of the upper end of the hollow cylinder, the end of this hole is hooked on the piston part, which causes durability and durability.
This impairs work efficiency, and even if it is possible to generate a damping force near the IG, the magnitude of the damping force cannot be arbitrarily adjusted.

Therefore, the purpose of the present invention is to prevent air ration from occurring, and to prevent the tube hole from getting caught on the piston part and deteriorating durability and operability.
The damping force can be adjusted arbitrarily in the normal operating range near the IG, and when operating further to the extension side beyond the vicinity of the IG, the necessary damping force can be obtained and the shock of extension can be alleviated. It is an object of the present invention to provide a hydraulic shock absorber suitable for use in a front fork, rear action unit, etc. of a two-wheeled vehicle.

To achieve this objective, the structure of the present invention is that an inner tube is slidably inserted into an outer tube, a hollow cylinder is erected at the lower end of the outer tube toward the inner tube, and the upper end of the hollow cylinder is provided. The outer periphery of the piston is brought into sliding contact with the inner periphery of the inner tube via a check valve, and the outer tube and inner tube are divided into two upper and lower liquid chambers via a check valve provided at the bottom of the inner tube. In a hydraulic shock absorber, an annular groove of a predetermined width is formed between an inner tube and an outer tube in a hydraulic shock absorber having an upper liquid chamber and a lower liquid chamber above and below the cylinder, each having orifices that communicate with the inside of the hollow cylinder. , this annular groove communicates with the upper liquid chamber through a hole bored in the inner tube and opening into the upper liquid chamber, and this bypass passage communicates the upper liquid chamber with the lower liquid chamber in the normal operating range. Further, an externally adjustable orifice is disposed in the bypass flow path to make the damping force variable only within the normal operating range.

An embodiment of the present invention will be described below with reference to the drawings.

An inner tube 2 is slidably inserted into an outer tube 1, and the lower end of the outer tube 1 is fixed to a wheel of a motorcycle or the like via a mounting bracket 4 and an eye 5, and the inner tube 2 is fixed to the vehicle body side. .

A hollow cylinder 6 stands up in the inner tube 2 from the center of the lower end of the outer tube 1, a piston part is formed at the upper end of the hollow cylinder 6, and a check valve 7 is formed on the outer periphery of the piston part, which is movable up and down.
It comes into contact with the inner periphery of the inner tube 2 via. A spring 9 is interposed between the upper spring receiver 8 of the inner tube 2 and the upper end of the hollow cylinder 6 to constantly push the inner tube 2 upward.

Inside the inner tube 2 and outer tube 1, there is a check valve 1 installed at the bottom of the inner tube.
9 and the two lower liquid chambers 1 via the lock piece 3.
The hollow cylinder 6 and the inner tube 2 are filled with hydraulic oil up to the oil level 12 to form a liquid chamber 13, and the inner tube 2 is further filled with hydraulic oil above the oil level 12. gas chamber 14
This gas chamber 14 is filled with air or other gas through a valve 5.

The upper liquid chamber 10 and the liquid chamber 13 in the hollow cylinder 6 communicate with each other via an orifice 16 bored above the hollow cylinder 6, and the lower liquid chamber 11 communicates with the liquid chamber 13 in the hollow cylinder 6.
communicates through an orifice 17 bored below the
The upper orifice 16 cooperates with the variable orifice 35 in the bypass in the normal operating range during extension, and when this range is exceeded, it independently generates the damping force on the extension side, and the lower orifice 17 produces the damping force on the compression side. is beginning to occur.

A passage 18 is formed in the vertical direction in the lock piece 3, and a check valve 19 is disposed in this passage 18. During compression, oil in the lower liquid chamber 11 passes through the passage 18 and the check valve 19 to the upper liquid chamber 10. It's starting to leak out.

A spring 20 is loosely fitted above the lock piece 3 and has a cushioning effect to prevent the lock piece 3 from colliding with the upper end of the hollow cylinder 6 when the inner tube 2 is fully extended. Also, an oil hole rod 21 is erected on the outer periphery of the lower end of the hollow cylinder 6, and when the inner tube 2 is fully compressed, it is fitted into the passage 18 of the lock piece 3 to restrict the flow of oil, thereby preventing the inner tube 2 from bottoming out. I'm starting to do that.

Next, an annular groove 22 is defined between the outer periphery of the inner tube 2 and the inner periphery of the outer tube 1 by forming an annular groove of a predetermined width corresponding to the normal operating range near the IG on the outer periphery of the inner tube 2. 22 is connected to the upper liquid chamber 10 through a hole 23 bored into the inner tube 2 and opened to the upper liquid chamber 10.
It communicates with However, the annular groove may be cut out in the inner circumference of the outer tube 1.

Port blocks 24 and 25 are connected to the outside of the outer tube 1 via connecting members 32 and 33 that are integrally attached to the pipe 28, and the annular groove 22 is connected to the port block 24 and the connecting member 32 located above. Passages 26a and 26b communicating with the lower liquid chamber 11 are bored, and passages 27a and 27a communicating with the lower liquid chamber 11 are formed in the lower port block 25 and the connecting member 33.
7b, and these passages are communicated with each other by the pipe 28 to form a bypass passage.

Furthermore, 30 and 31 are port blocks 24 and 25.
This is a seal that prevents oil from leaking between the connecting members 32 and 33.

A hollow valve body 34 is rotatably fitted from the outside into the passage 26a of the upper port block 24, and a plurality of orifices 35 having different diameters are provided at the tip of the valve body 34. The valve body 34 is pushed toward the port block 24 side by a spring 36 at the outer end, and a locking ball 37 is interposed between the valve body 34 and the port block 24, so that when the valve body 34 is rotated with a screwdriver etc. This locking ball 37 is fitted into a locking means such as a groove so that the valve body 34 can be positioned at any desired position. When the valve body 34 is rotated to a certain position, one of the orifices 35 faces the pipe 28 side corresponding to the position 26b.
through the orifice 35 and the passage 26
a, 26b and the pipe 28 communicate with each other. This orifice 35 generates a damping force during expansion within the normal operating range, and by rotating the valve body 34 and selecting an arbitrary orifice 35, a damping force corresponding to the size of the orifice 35 can be freely generated externally. can be adjusted.

Next, we will discuss the operation.

Fig. 4 is a graph showing the spring characteristics (P) when the Y axis is the spring load (W) and the X axis is the stroke (S), where point a is the most extended position, point b is the most compressed position,
Further, point O indicates the balance position of the inner tube 2, that is, the IG state. Fig. 5 is a graph showing the damping force characteristics at the same speed when the Y-axis is the extension damping force (F) and the X-axis is the stroke (S), and depending on the selection of the orifice 35 the damping force characteristics Q1, Q
2...Qn, where point a is the most extended position, point b is the most compressed position, and point O is the balance position of the inner tube 2. However,
FIGS. 1 and 2 show cross-sectional views of the hydraulic shock absorber in a balanced state at point O, and the normal operating range is centered around this position.

In the figure, the extension stroke l from the balance position of point O
1. In the stroke range of the compression stroke l2, the upper liquid chamber 10 includes the hole 23, the circular groove 22, the passage 26a, the orifice 35, the passage 26b, the pipe 28, and the passage 27.
b. It communicates with the lower liquid chamber 11 via the passage 27a. In the extension stroke in the range l1 from the balance position, when the largest diameter of the orifice 35 faces the passage 26b, the damping force characteristic is Q1, and
When the smallest diameter is set, the damping force characteristic becomes Qn.

Therefore, when the inner tube extends within the stroke range l1, the hydraulic oil in the liquid chamber 10 flows into the orifice 1.
6 to the liquid chamber 13 on the hollow cylinder 6 side, and some of it flows through the hole 23, the annular groove 22, the passage 26a,
It is discharged to the lower liquid chamber 11 side via the orifice 35, the passage 26b, the pipe 28, the passage 27b, and the passage 27a.
By this action, a damping force as set in the range l1 in FIG. 5 is obtained. Furthermore, when the inner tube 2 extends beyond the range l1, the outer periphery of the inner tube 2 below the annular groove 22 becomes the passage 2.
6a is sealed, and in this case, a high damping force is generated by the orifice 16 as shown in section n in FIG. obtained,
Further, when the inner tube 2 is further expanded and the valve 19 of the lock piece 3 closes the orifice 16, a high damping force as shown in section m due to oil leakage is obtained. In the range r where the state moves from the most compressed position b to the extended state, the outer periphery above the annular groove 22 of the inner tube 2 closes the passage 26a in advance, so the hydraulic oil in the liquid chamber 10 flows from the orifice 16 to the hollow cylinder 6. The liquid flows out to the liquid chamber 13 side, and at that time, the damping force characteristic is obtained only by the orifice 16. For this reason, even if the orifice 16 is bored in the lock piece portion 3, the practical effect is the same.

Furthermore, when the inner tube 2 expands, the upper end of the annular groove 22 opens into the passage 26a, and in the range l2 shown in FIG.
…One of Qn occurs.

Note that when the inner tube 2 is compressed, the liquid chamber 11
The hydraulic oil flows out from the orifice 17 into the liquid chamber 13 of the hollow cylinder 6, and also flows into the liquid chamber 10 through the passage 18 and the valve 19, and at this time, the orifice 17 provides a damping force on the pressure side.

Furthermore, the check valve 7 closes the upper liquid chamber 10 during expansion, but opens during compression to suck hydraulic oil from the upper oil chamber into the upper liquid chamber 10.

The present invention has the following effects.

The damping force can be adjusted arbitrarily only within the normal operating range near the IG. This allows the optimum damping force to be obtained depending on the road surface and driving conditions. Furthermore, in the latter half of the stroke where the spring constant is high or near the end of extension, the necessary damping force can be obtained by the orifice provided in the hollow cylinder, regardless of the damping force adjustment, and the impact of the end of extension can be alleviated.

By connecting the bypass flow path for damping force adjustment from the upper liquid chamber to the lower liquid chamber via external piping, the flow velocity inside the hollow cylinder during the extension stroke is reduced, thereby minimizing air entrainment. , which can prevent the occurrence of aeration.

The orifice of the hollow cylinder does not interfere with the check valve or lock piece of the inner tube, and the check valve provided on the outer periphery of the piston at the upper end of the hollow cylinder does not interfere with the hole of the inner tube, so it cannot be hooked on the piston ring as in the conventional case. There is no deterioration in durability or operability.

[Brief explanation of the drawing]

The attached drawings relate to one embodiment of the present invention, and FIG. 1 is a longitudinal side view, FIG. 2 is a partially cutaway longitudinal plan view, FIG. 3 is a partially enlarged plan view of FIG. 2, and FIG. The figure is a graph showing spring characteristics, and FIG. 5 is a graph showing rebound damping force characteristics. 1... Outer tube, 2... Inner tube, 3... Lock piece, 6... Hollow cylinder, 10... Upper liquid chamber, 11... Lower oil chamber, 1
6, 17... Orifice, 22... Annular groove, 23
... Hole, 24, 25 ... Port member, 28 ... Pipe, 34 ... Valve body, 35 ... Variable orifice.

Claims (1)

[Claims for Utility Model Registration] (1) An inner tube is slidably inserted into an outer tube, a hollow cylinder is erected toward the inner tube at the lower end of the outer tube, and a hollow cylinder is provided at the upper end of the hollow cylinder. The outer periphery of the piston is brought into sliding contact with the inner periphery of the inner tube via a check valve, and the outer tube and inner tube are divided into two upper and lower liquid chambers via a check valve provided at the bottom of the inner tube. In a hydraulic shock absorber, an annular groove of a predetermined width is formed between an inner tube and an outer tube in a hydraulic shock absorber equipped with orifices above and below the cylinder that allow the upper liquid chamber and the lower liquid chamber to communicate into the hollow cylinder, respectively. , this annular groove communicates with the upper liquid chamber through a hole bored in the inner tube and opening into the upper liquid chamber, and the annular groove and the lower liquid chamber are communicated with each other through a bypass passage provided by external piping for normal operation. A hydraulic shock absorber in which an upper liquid chamber communicates with a lower liquid chamber in the range, and a variable orifice that can be adjusted from the outside is disposed in the bypass flow path. (2) The hydraulic shock absorber according to claim 1, wherein the annular groove is formed on either the outer circumference of the inner tube or the inner circumference of the outer tube. (3) Two port members are provided in the outer tube, and these port members communicate with the upper and lower liquid chambers through a bypass, respectively, and a variable orifice is incorporated in one of the port members.Claim 1 of Utility Model Registration Hydraulic shock absorber as described in section. (4) The hydraulic shock absorber according to claim 1 or 3, wherein the variable orifice comprises a plurality of orifices of different diameters bored in a hollow valve body.