JP2003049889A - Front fork - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To control a reaction force of a vehicle body side tube or a piston rod according to a road surface condition, and also to control a spring load characteristic of a suspension spring. SOLUTION: A free piston 8 having a throttle 9 formed corresponding to a vehicle body side tube or a piston rod is provided, and the free piston (8) is biased to one side by a spring (11, 30) or a suspension spring. (15, 18).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front fork that is also interposed between a vehicle body and a front wheel of a motorcycle and absorbs and absorbs shock such as vibration from a road surface.

[0002]

2. Description of the Related Art As a front fork of this type, for example, one disclosed in Japanese Patent Laid-Open No. 2000-27921 has been developed.

In this front fork, an inner tube is slidably inserted into an outer tube, a damper cylinder is erected at the bottom of the inner tube, and a piston rod is movably inserted into the damper cylinder via a piston. The outer end of the rod is connected to the outer tube, and the outer tube and the piston rod are constantly urged in the extending direction via a suspension spring. A cylindrical guide is erected on the upper end of the damper cylinder, and a free piston is movably arranged vertically along the guide. The free piston divides an upper reservoir and a lower oil chamber in an inner tube. In addition, one end of the suspension spring is carried.

In the conventional front fork described above, the suspension spring is compressed by the compression stroke and the movement of the free piston due to the change in the amount of oil in the excess volume caused by the rod entering the damper cylinder. It is possible to increase the internal pressure of the damper cylinder depending on the stroke to increase the reaction force acting on the rod and increase the load characteristic of the suspension spring.

[0005]

In the above-mentioned conventional front fork, since the rod reaction force and the load characteristics of the suspension spring become large depending on the compression operation stroke, for example, when traveling in a wasteland such as a motocross specification, When there is a high-speed large input from the road surface, the shock absorption is improved, but when traveling on a good road where a high-speed large input does not occur, there is a problem that the riding comfort becomes worse.

Therefore, a first object of the present invention is to increase the reaction force against the tube or piston rod on the vehicle body side during running such as a motocross specification in which a high-speed large input is generated, and conversely a high-speed large input is not generated. It is an object of the present invention to provide a front fork that improves the riding comfort by reducing the reaction force during traveling to obtain the reaction force of the vehicle body side tube or the piston rod according to the road surface condition.

Similarly, the second purpose is to increase the reaction force against the tube or piston rod on the vehicle body side and increase the spring load characteristic of the suspension spring in the traveling in which a large high-speed input is generated by utilizing the suspension spring. Provide a front fork that improves the riding comfort by reducing the reaction force and the spring load characteristic to obtain the reaction force and the spring load characteristic corresponding to the road surface condition when traveling on a good road where a high-speed large input does not occur. That is.

[0008]

In order to achieve the above object, a first means of the present invention is that a vehicle body side tube and a wheel side tube are slidably fitted and a damper is provided at the bottom of the wheel side tube. The cylinder is erected, the piston rod is movably inserted into the damper cylinder via the piston, the piston rod is interlocked with the vehicle body side tube, and the suspension spring is interposed between the damper cylinder and the vehicle body side tube. In a front fork provided with a reservoir consisting of a lower oil chamber and an upper gas chamber communicating with the oil chamber in the damper cylinder outside the cylinder, a free piston is movably inserted into the lower oil chamber. A spring that urges the free piston downward is provided between the upper part of the free piston and the damper cylinder. In which it characterized in that a stop which through.

Similarly, the second means is that the tube on the vehicle body side and the tube on the wheel side are slidably fitted, the damper cylinder is erected at the bottom of the wheel side tube, and the piston rod is inserted in the damper cylinder via the piston. In a front fork that is movably inserted, a piston rod is interlocked with a vehicle body side tube, and a reservoir including a lower oil chamber and an upper gas chamber that communicate with an oil chamber in the damper cylinder is provided outside the damper cylinder. The free piston carried on the upper part of the damper cylinder is movably inserted into the lower oil chamber, and a suspension spring is interposed between the upper part of the free piston and the body side tube. It is characterized in that a diaphragm passing therethrough is provided.

Similarly, the third means is that the vehicle body side tube is slidably inserted into the wheel side tube, the seat pipe is erected at the bottom of the wheel side tube, and the vehicle body side tube and the upper gas chamber are inside the seat pipe. And a lower oil chamber are provided, and an upper oil chamber and a lower oil chamber, which are partitioned by a check valve provided at the lower portion of the vehicle body side tube, are provided outside the seat pipe, and an upper oil chamber and a lower oil chamber are provided. In a front fork communicating with the lower oil chamber through an orifice formed in the seat pipe, a free piston slidingly contacting the inner circumference of the seat pipe is vertically movably inserted into the lower oil chamber, A spring that urges the free piston downward is provided between the upper portion of the free piston and the seat pipe, and a throttle that vertically penetrates the free piston is provided. The one in which the features.

Similarly, the fourth means is that the vehicle body side tube is slidably inserted into the wheel side tube, the seat pipe is erected at the bottom of the wheel side tube, and the upper gas chamber is provided in the vehicle body side tube and the seat pipe. A reservoir consisting of a lower oil chamber is provided, and an upper oil chamber and a lower oil chamber, which are partitioned by a check valve provided at the lower part of the vehicle body side tube, are provided outside the seat pipe, and the upper oil chamber and the lower oil chamber are connected. A front fork communicating with the lower oil chamber through an orifice formed in the seat pipe, and a free piston that is carried on the seat pipe in the lower oil chamber and slidably contacts the inner circumference of the vehicle body side tube. The suspension spring is provided between the upper part of the free piston and the tube on the vehicle body side, and the free piston is provided with a throttle that penetrates vertically. It is an.

In each of the above means, it is preferable that the downward stroke of the free piston is restricted.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The front forks shown in FIGS. 1 and 3 are of a type for increasing the reaction force of the piston rod or the vehicle body side tube at the time of large input at high speed.

The front fork shown in FIGS. 2 and 4 is of a type in which the reaction force of the piston rod or the vehicle body side tube and the spring load characteristic of the suspension spring are increased at high speed and large input.

Each embodiment will be described below.

FIG. 1 relates to an embodiment of the present invention, in which an inner tube, which is a wheel-side tube 2, is slidably inserted into an outer tube, which is a vehicle-body-side tube 1. The damper cylinder 3 is erected, and the piston rod 4 is movably inserted into the damper cylinder 3 via the piston 12,
Is connected to the vehicle body side tube 1, a suspension spring 15 is interposed between the damper cylinder 3 and the vehicle body side tube 1, and the lower side communicating with the piston side oil chamber 5 in the damper cylinder 3 is provided outside the damper cylinder 3. It is a front fork provided with a reservoir R composed of an oil chamber 6 and an upper gas chamber 7.

In the present invention, a free piston 8 which slidably contacts the inner circumference of the wheel-side tube 2 and the outer circumference of the damper cylinder 3 is movably inserted into the lower oil chamber 6, and the upper portion of the free piston 8 and the damper cylinder are inserted. A spring 1 for urging the free piston 8 downward between it and the collar 10 on the 3 side.
1, a free piston 8 is further provided with a diaphragm 9 such as an orifice penetrating in the vertical direction.

In the damper cylinder 3, a piston 12 is provided inside the damper cylinder 3 by means of a lower piston side oil chamber 5 and an upper rod side oil chamber 5b.
The two oil chambers 5 and 5b communicate with each other through the expansion side port 12a provided in the piston 12, a pressure side port (not shown), and the oil passage 13 provided in the piston rod 4, and the expansion side port 12a. A compression-side damping valve 14 and an expansion-side damping valve 15 are openably and closably provided at the outlet end of a compression-side port (not shown), and a needle valve 16 is provided in the middle of the oil passage 13. The needle valve 16 is driven from the outside in the vertical direction via the control rod 17 to adjust the opening area of the oil passage 13.

A cylinder head 18 is screwed onto the upper part of the damper cylinder 3 and stands upright, and a collar 10 is formed on the outer circumference of the cylinder head 18.

As described above, the collar 10 and the free piston 8
A spring 11 is provided between the flange 10 and the vehicle body side tube 1, and a suspension spring 15 is provided between the flange 10 and the vehicle body side tube 1. The collar 10 may be provided on the damper cylinder 3 itself.

The lower oil chamber 6 in the reservoir R communicates with the piston-side oil chamber 5 via a port provided in the damper cylinder 3 or a compression side damping force generating mechanism.

The free piston 8 is composed of a main body having a diaphragm 9 and a seal provided on the outer periphery of the main body. The free piston 8 is constantly urged downward by a spring 11 and a snap ring provided on the damper cylinder 3 or the like. The lowering stroke is restricted by the stopper 19 of.

In the above-mentioned front fork, the oil in the rod side oil chamber 5b flows out to the piston side oil chamber 5 through the extension port 12a and the oil passage 13 during the extension operation, and at this time, the extension side damping valve 15 and the needle valve. 16 produces a damping force on the extension side. Oil corresponding to the withdrawal volume of the piston rod 4 is introduced from the reservoir R into the piston side oil chamber 5. During the compression operation, the oil in the piston side oil chamber 5 is not shown in the drawing, and the pressure port and oil passage 13
Through the rod side oil chamber 5b, and at this time, the pressure side damping valve 14 and the needle valve 16 generate a pressure side damping force. The amount of oil that has entered the piston rod 4 is discharged from the piston-side oil chamber 5 to the reservoir R.

By the way, in the above compression operation, the piston rod 4 slowly descends when the vehicle is traveling on a good road where a high-speed large input does not occur. At this time, the amount of oil that has entered the piston rod 4 is stored in the reservoir R from the piston side oil chamber 5.
In the lower oil chamber 6 and the oil in the lower oil chamber 6 flows out to the upper side of the reservoir R through the throttle 9 of the free piston 8. Flow resistance is small. Therefore, riding comfort on a good road does not deteriorate.

On the other hand, the piston rod 4 descends at a high speed when the vehicle travels in a wasteland like a motocross and there is a large high-speed input from the road surface. At this time, similarly to the above, the oil in the piston side oil chamber 5 flows out to the lower oil chamber 6, but in this case the flow velocity of the oil is high and a differential pressure is generated before and after the throttle 9, and the flow resistance is reduced in the throttle 9. At the same time, since the free piston 8 is urged downward by the spring 11 and its upward movement is restricted, the lower oil chamber 6 and the piston side oil chamber 5 are generated.
The internal pressure rises, the reaction force against the piston rod 4 increases, and the shock absorbability for high-speed and large input can be improved. That is,
A piston rod reaction force that depends on the speed of the piston rod can be obtained.

FIG. 2 relates to another embodiment of the present invention, in which the basic structure of the front fork is the same as that in FIG. 1, but in addition to the reaction force control of the piston rod, the load characteristic of the suspension spring is also provided. It can be controlled according to the compression speed.

In this embodiment, the damper cylinder 3
The cylinder head 18 is erected on the upper part of the cylinder head 18, and the free piston 8 is slidably contacted vertically between the outer circumference of the cylinder head 18 and the inner circumference of the wheel side tube 2, and the upper part of the free piston 8 and the body side tube 1 Suspension spring 1 between
5 is interposed. However, the free piston 8 may be in sliding contact with the outer circumference of the damper cylinder 3 itself. The downward stroke of the free piston 8 is restricted by a step portion 19a formed on the lower outer periphery of the cylinder head 18, and the suspension spring 15 has a load carried by the damper cylinder 3 via the free piston 8 and the step portion 19a.

In this front fork, even if the piston rod descends during running on a good road, almost no differential pressure is generated before and after the free piston 8, so flow resistance due to the throttle 9 such as an orifice is small, and the compression amount of the suspension spring 15 is also small. Few. Therefore, the reaction force against the piston rod is small, and the thrust for bending the suspension spring 15 is also small or zero.

On the other hand, when a high-speed large input is input from the road surface while traveling on a wasteland, the piston rod 4 descends at a high speed, thereby generating a differential pressure before and after the free piston 8, and the lower oil chamber 6 and the oil on the piston side. The internal pressure of the chamber 5 is increased and the reaction force of the piston rod 4 is increased.

On the other hand, in addition to the compression stroke associated with the compression operation, the suspension spring 15 raises the free piston 8 by the internal pressure of the lower oil chamber 6 and compresses the suspension spring 15, thereby increasing the spring load characteristic.

That is, in this embodiment, the reaction force of the piston rod and the spring load characteristic of the suspension spring can be controlled according to the compression speed of the piston rod.

Other structures, actions and effects are the same as those of the embodiment shown in FIG. Therefore, the same reference numerals are given to the same structures, and the details are omitted.

In the embodiments shown in FIGS. 1 and 2, the inverted front fork in which the wheel side tube 2 is slidably fitted in the vehicle body side tube 1 has been described.
On the contrary, the present invention can be applied to an upright front fork in which the vehicle body side tube 1 is slidably fitted in the wheel side tube 2 and the operation and effect are the same. Therefore, the free piston 8 is in sliding contact with the inner circumference of the tube arranged inside.

FIG. 3 relates to another embodiment of the present invention, which relates to a front fork provided with a seat pipe. Similar to a general front fork, this front fork has a vehicle body side tube 21 slidably inserted into a wheel side tube 22, a seat pipe 23 is erected at the bottom of the wheel side tube 22, and the vehicle body side tube 21 and the seat Inside the pipe 23, an upper gas chamber 24 and a lower oil chamber 25
A check valve 2 provided with a reservoir R composed of and a lower part of the vehicle body side tube 21 outside the seat pipe 23.
An upper oil chamber 27 and a lower oil chamber 28 divided by 6 are provided,
The upper oil chamber 27 and the lower oil chamber 28 are communicated with the lower oil chamber 25 via orifices 29 formed in the seat pipe 23, respectively. Further, in the present invention, the free piston 8 slidingly contacting the inner circumference of the seat pipe 23 is inserted into the lower oil chamber 25 so as to be vertically movable,
A spring 30 for urging the free piston 8 downward is provided between the upper portion of the free piston 8 and the seat pipe 23, and the free piston 8 is further provided with a throttle 9 penetrating vertically.

In the above-mentioned front fork, a suspension spring 31 is further interposed between the upper end of the seat pipe 23 and the vehicle body side tube 21 to constantly bias the vehicle body side tube 21 in the extending direction. A piston portion 32 is provided above the seat pipe 23, and the inner circumference of the vehicle body side tube 21 is in sliding contact with the outer circumference of the piston portion 32. A cushion spring 33 is provided below the piston portion 32 so that the cushion is effective when it is fully extended.

The free piston 8 is composed of a main body and a seal on the outer circumference of the main body. The free piston 8 is constantly urged downward by a spring 30 and its downward stroke is restricted by a stopper 34 provided on the inner circumference of the seat pipe 23. ing.

The upper end of the spring 30 is the seat pipe 23.
It is supported by a stopper 35 including a snap ring, a stepped portion, etc. provided on the inner circumference of the upper part of the.

In the above-mentioned front fork, the vehicle body side tube 21 rises during extension operation, at which time the check valve 26 shuts off the passage, and the oil in the upper oil chamber 27 makes the orifice 2
The expansion side damping force is generated by flowing out to the reservoir R via 9 and oil corresponding to the withdrawal volume of the vehicle body side tube 21 is introduced from the lower oil chamber 25 in the reservoir R via the orifice below the seat pipe 23. .

During the compression operation, the vehicle body side tube 21 descends, and the oil in the lower oil chamber 28 flows out to the upper oil chamber 27 via the check valve 26 and to the reservoir R via the lower orifice so that the pressure side damping force is exerted. To occur.

In the above compression operation, the vehicle body side tube 21 slowly descends while the vehicle is traveling on a good road. Therefore, the oil that has flowed from the lower oil chamber 28 to the lower oil chamber 25 of the reservoir R flows to the upper side of the reservoir R via the throttle 9, but there is almost no differential pressure before and after the throttle 9 and the lower oil chamber is not generated. Since the internal pressure of 25 does not rise, the reaction force against the vehicle body side tube 21 is small. Therefore, the riding comfort while traveling on a good road is improved. On the other hand, when a high-speed large input is input during traveling on a wasteland, the vehicle body side tube 21 descends at high speed. At this time, the lower oil chamber 2
When oil flows from the lower oil chamber 25 into the lower oil chamber 25, a differential pressure is generated before and after the throttle 9.
Since the upward movement is restricted by, the free piston 8 moves only slightly, and the internal pressure of the lower oil chamber 25 rises. Therefore, the reaction force against the vehicle body side tube 21 is increased, and the shock absorption at the time of compression can be improved. That is, in this embodiment, the reaction force can be controlled depending on the compression speed of the vehicle body side tube.

FIG. 4 relates to another embodiment of the present invention. The basic structure of this front fork is the same as that of FIG. 3, but the load characteristic of the suspension spring is compressed in addition to the pressure control of the vehicle body side tube. It can be controlled according to the speed.

In this embodiment, the free piston 8 is carried by the upper end of the seat pipe 23, and a suspension spring is interposed between the upper portion of the free piston 8 and the vehicle body side tube 21. The free piston 8 is provided with a vehicle body and a seal on the outer circumference, forms a diaphragm 9 that penetrates the vehicle body in the vertical direction, and the outer circumference of the free piston 8 is slidably contacted with the inner circumference of the vehicle body side tube 21.

At the time of expansion / contraction movement, damping force is generated by the upper orifice 29 and the lower orifice as in the embodiment of FIG. Tube 2 on the vehicle body side during compression operation when driving on a good road
1 slowly descends, as a result, no differential pressure is generated before and after the throttle 9, and the internal pressure of the lower oil chamber 25 hardly rises.
Therefore, the free piston 8 hardly rises. Therefore, the reaction force to the vehicle body side tube 21 is small, and the spring load characteristic of the suspension spring 31 only corresponds to the compression stroke. On the other hand, when a high-speed large input is input from the road surface due to traveling on a wasteland, the vehicle body side tube 21 descends at a high speed, which causes a differential pressure before and after the free piston 8, and an increase in the internal pressure of the lower oil chamber 25 causes a vehicle body side tube. 21, the free piston 8 is also slightly pushed up to compress the suspension spring 31, and the suspension spring 31 is added to the descending stroke amount.
The spring load characteristic is increased by the amount of compression by being pressed by the free piston 8. That is, in this embodiment, it is possible to obtain a reaction force and a spring load characteristic that depend on the compression speed of the vehicle body side tube 21.

[0045]

According to the present invention, the following effects can be obtained.

(1) According to the invention of each claim, when the speed of the descending stroke of the piston rod or the tube on the vehicle body side is slow, a differential pressure is not generated before and after the free piston, so that the vehicle runs on a good road. In this case, the reaction force against the piston rod or the vehicle body side tube is small, and conversely, when the speed of the descending stroke is high, a differential pressure is generated before and after the free piston to increase the reaction force against the piston rod or the vehicle body side tube. it can. In other words, the reaction force can be reduced when traveling on a good road, the reaction force can be increased when traveling on a wasteland, and the reaction force can be controlled according to the compression speed and the road surface condition, so that the riding comfort of the vehicle can be improved.

(2) According to the second and fourth aspects of the present invention, in addition to the above effects, the spring load characteristics of the suspension spring can be controlled in magnitude depending on the compression speed and the road surface condition, so the shock absorption can be improved. The ride quality can be improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway vertical front view of a front fork according to an embodiment of the present invention.

FIG. 2 is a partially cutaway vertical front view of a front fork according to another embodiment.

FIG. 3 is a partially cutaway vertical front view of a front fork according to another embodiment.

FIG. 4 is a partially cutaway vertical front view of a front afork according to another embodiment.

[Explanation of symbols]

1,21 Body tube 2,22 Wheel side tube 3 damper cylinder 4 piston rod 5 oil chamber 6 lower oil chamber 7 Upper gas chamber 8 free piston 9, aperture 11,30 spring 12 pistons 15,31 suspension spring 23 seat pipe 24 gas chamber 25 Oil chamber below 26 Check valve 27 Upper oil chamber 28 Lower oil chamber 29 Orifice R reservoir

Claims (5)

[Claims] 1. A vehicle body side tube and a wheel side tube are slidably fitted, a damper cylinder is erected at the bottom of the wheel side tube, and a piston rod is movably inserted into the damper cylinder via a piston. , A piston rod is interlocked with the vehicle body side tube, a suspension spring is interposed between the damper cylinder and the vehicle body side tube, and a lower oil chamber and an upper gas chamber that communicate with the oil chamber inside the damper cylinder are provided outside the damper cylinder. In a front fork provided with a reservoir composed of a free piston, a free piston is movably inserted into the lower oil chamber, and a spring for urging the free piston downward is provided between the upper portion of the free piston and the damper cylinder. A front fork characterized in that a free piston is further provided with a throttle penetrating vertically. 2. A vehicle body side tube and a wheel side tube are slidably fitted together, a damper cylinder is erected at the bottom of the wheel side tube, and a piston rod is movably inserted into the damper cylinder via a piston. In the front fork provided with a reservoir composed of a lower oil chamber and an upper gas chamber communicating with an oil chamber in the damper cylinder, the piston fork is interlocked with the tube on the vehicle body side, and the lower oil is A free piston carried by the upper part of the damper cylinder is movably inserted into the room, and a suspension spring is interposed between the upper part of this free piston and the tube on the vehicle body side. A front fork characterized by being provided. 3. A vehicle body side tube is slidably inserted into a wheel side tube, a seat pipe is erected at a bottom portion of the wheel side tube, and an upper gas chamber and a lower oil chamber are provided in the vehicle body side tube and the seat pipe. And an upper oil chamber and a lower oil chamber, which are partitioned by a check valve provided in the lower portion of the vehicle body side tube, are provided outside the seat pipe, and the upper oil chamber and the lower oil chamber are respectively formed by the seat pipe. In the front fork communicating with the lower oil chamber through the orifice formed in, the free piston that slides in contact with the inner circumference of the seat pipe is vertically movably inserted into the lower oil chamber, and the upper portion of the free piston A Freon characterized in that a spring for urging the free piston downward is provided between the seat and the seat pipe, and that the free piston is provided with a throttle penetrating vertically. Tofolk. 4. A vehicle body side tube is slidably inserted into a wheel side tube, a seat pipe is erected at the bottom of the wheel side tube, and an upper gas chamber and a lower oil chamber are provided in the vehicle body side tube and the seat pipe. Is provided, and an upper oil chamber and a lower oil chamber, which are partitioned by a check valve provided in the lower portion of the vehicle body side tube, are provided outside the seat pipe, and the upper oil chamber and the lower oil chamber are respectively provided in the seat pipe. In the front fork communicating with the lower oil chamber through the formed orifice, a free piston that is carried on the seat pipe and slidably contacts the inner circumference of the vehicle body side tube is provided in the lower oil chamber. A front spring is characterized in that a suspension spring is interposed between the upper part and the tube on the vehicle body side, and a free piston is provided with a throttle penetrating vertically. Ku. 5. The front fork according to claim 1, 2, 3 or 4, wherein the descending stroke of the free piston is restricted.