JP4540833B2 - Hydraulic shock absorber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is suitable for the use of a front fork interposed between a front wheel axle and a vehicle body such as a motorcycle or a bicycle, or a rear cushion unit interposed between a rear wheel axle and a vehicle body, and particularly compression. The present invention relates to a hydraulic shock absorber capable of changing a damping force depending on a stroke position during operation.
[0002]
[Prior art]
Examples of hydraulic shock absorbers used as a front fork of a motorcycle include, for example, Japanese Utility Model Laid-Open No. 60-20493, Japanese Utility Model Laid-Open No. 60-148791, Japanese Utility Model Laid-Open No. 52-146461, and Japanese Patent Application Laid-Open No. 1-190595. Has been developed.
[0003]
The hydraulic shock absorber shown in Japanese Utility Model Publication No. 60-20493 uses the pressure change in the damper to change the damping force, and the suspension spring characteristic of this hydraulic shock absorber compensates the coil spring and the volume change inside. The combined characteristics with the air spring of the air chamber to be used.
[0004]
The hydraulic shock absorber disclosed in Japanese Utility Model Laid-Open No. 60-184791 changes the damping force by using the change of the suspension spring load.
[0005]
The hydraulic shock absorber disclosed in Japanese Utility Model Laid-Open No. 52-146461 changes the damping force by sequentially changing the throttle flow area for generating the damping force according to the stroke position, and corresponds to the stroke position. It is possible to change the damping force with certainty, and a damping force characteristic depending on the position can be obtained in both directions of stretching.
[0006]
Further, the hydraulic shock absorber disclosed in Japanese Patent Application Laid-Open No. 1-190595 also electrically changes the damping force in accordance with the stroke position, and is provided with an electric control system for that purpose.
[0007]
[Problems to be solved by the invention]
However, each of the hydraulic shock absorbers disclosed in the above publication has the following problems, and improvements are desired.
[0008]
First, the hydraulic shock absorber disclosed in Japanese Utility Model Laid-Open No. 60-20493 is based on a compression operation because the damping force is changed by utilizing the pressure change in the damper to obtain the characteristics of synthesis with the gas spring. If the valve characteristic of the pressure side valve for generating the pressure side damping force for increasing the pressure in the damper is changed, the gas spring characteristic is changed. That is, there is no flexibility in setting gas spring characteristics and valve characteristics. If the extension side damping force is also changed depending on the internal pressure, the extension side valve must be configured like the compression side valve, resulting in a structural complexity.
[0009]
Secondly, in the hydraulic shock absorber shown in Japanese Utility Model Laid-Open No. 60-184791, the damping force of the compression side valve is changed by utilizing the increase of the suspension spring load based on the compression operation. The damping force characteristics of the compression side valve will also change, and there is no flexibility in setting the suspension spring characteristics and valve characteristics. Furthermore, if the extension side damping force is changed depending on the suspension spring load, the extension side valve must be configured like a compression side valve, and the structure becomes complicated.
[0010]
Thirdly, the hydraulic shock absorber disclosed in Japanese Utility Model Laid-Open No. 57-146461 can change the damping force reliably in accordance with the stroke position, and obtain the damping force characteristic in accordance with the stroke position in both directions of pressure expansion. However, there is a problem that the damping force of the square characteristic suddenly increases due to an increase in the flow rate due to high-speed operation and the ride comfort of the vehicle becomes worse.
[0011]
Fourthly, the hydraulic shock absorber disclosed in Japanese Patent Application Laid-Open No. 1-190595 can also obtain a damping force corresponding to the stroke position using the electric control system, but the electric control system is absolutely necessary, resulting in an increase in cost. There is a problem.
[0012]
Accordingly, an object of the present invention is to provide a hydraulic buffer that is flexible in setting damping force characteristics, does not suddenly increase damping force, has a simple structure, can reduce costs, and can obtain damping force that depends on the compression stroke position. Is to provide a vessel.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, one means of the present invention is to movably insert a piston rod into a cylinder through a piston and guide the piston rod through a seal provided at the end of the cylinder. The piston partitions the rod-side oil chamber and the anti-rod-side oil chamber in the cylinder, and the two oil chambers communicate with each other via an extension-side damping valve and a pressure-side check valve provided in the piston, and the anti-rod-side oil chamber Is a hydraulic shock absorber that communicates with the reservoir via a base valve composed of a compression side damping valve and an extension side check valve, and in which the piston rod is always urged in the extension direction via a suspension spring. a small diameter portion of arbitrary length of the neighborhood, the small-diameter portion is continuously provided with a conical portion whose diameter increases upward constituted by a large diameter portion, the enlarged diameter or diametrically contractible band or ring the seal Or stretchable is configured lip rubber material having the above conical portion and the large diameter portion from the middle of the time compressed working is due to the increase of the rod intrusion volume upon entering the cylinder through the compression side damping valve The passing flow rate of the hydraulic oil is increased, and the damping force by the compression side damping valve is increased depending on the position of the compression stroke of the piston rod.
[0014]
Similarly, the other means is that the axle side inner tube is slidably inserted into the vehicle body side outer tube, the cylinder is erected at the bottom center of the inner tube, and the piston rod is movably inserted into the cylinder via the piston. The piston rod is guided through a seal provided at the end of the cylinder , the piston partitions the rod side oil chamber and the anti-rod side oil chamber in the cylinder, and the two oil chambers are provided in the piston. The extension side damping valve communicates with the pressure side check valve, the non-rod side oil chamber communicates with the reservoir via the base valve composed of the pressure side damping valve and the extension side check valve, and the piston rod is always connected via the suspension spring. In a hydraulic shock absorber biased in the extending direction, the piston rod has a small-diameter portion of an arbitrary length near the piston, and the small-diameter portion expands upward. It is composed of a large-diameter part continuously provided by a conical part having a diameter, and the seal is composed of a band or ring that can be expanded or contracted, or a rubber material provided with an extendable lip, and is in the middle of compression operation When the large diameter portion enters the cylinder, the flow rate of hydraulic oil passing through the compression side damping valve is increased due to an increase in the rod entry volume, and the pressure side depends on the compression stroke position of the piston rod. The damping force of the damping valve is increased.
[0017]
Similarly, the piston rod may be guided through a seal provided at the end portion of the piston and the cylinder, and the seal may be made of a rubber material provided with a telescopic lip.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
In the present embodiment, a front fork having an outer tube and an inner tube will be described. However, the present invention is also applied to a rear cushion unit and other general hydraulic shock absorbers that do not have an outer tube and an inner tube. Needless to say.
[0020]
FIG. 1 shows an embodiment of a hydraulic shock absorber applied as a front fork of a motorcycle.
[0021]
This hydraulic shock absorber is used as an inverted front fork, and its basic structure is such that an axle inner tube 2 is slidably inserted into a vehicle body outer tube 1 and a damper is provided at the bottom center of the inner tube 2. As a cylinder 3 is erected, a piston rod 5 interlocking with the outer tube 1 is movably inserted into the cylinder 3 through a piston 4 and a seal 17. The anti-rod side oil chamber 7 is partitioned, the two oil chambers 6 and 7 communicate with each other via an extension side damping valve 9 provided on the piston 4 and a pressure side check valve 10, and the anti-rod side oil chamber 7 is a pressure side damping valve. The piston rod 5 and the outer tube 1 are connected via a suspension spring 14 to a reservoir 8 via a base valve 13 composed of a cylinder 11 and an extension side check valve 12. It is one that is biased in the direction of growth time.
[0022]
In the present invention, the piston rod 5 is further formed into a small-diameter portion 5a having an arbitrary length near the piston 4 and a large-diameter portion 5b continuous above the small-diameter portion 5a. In this case, the small-diameter portion 5a and the large-diameter portion 5b are integrally formed smoothly and continuously through a conical portion 5c having an arbitrary length whose diameter increases toward the upper outside in the present embodiment. is there. However, the large diameter part 5b may be directly connected to the upper part of the small diameter part 5a, and the outer periphery of the lower end step part of the large diameter part may be tapered or bent.
[0023]
The reservoir 8 is constituted by an outer gas chamber 8 a in the outer tube 1 and the inner tube 2, and a lower oil chamber 8 b. The reservoir 8 is an oil chamber below the base valve 13 via a port 18 formed below the cylinder 3. 19 is connected. In this case, in a general hydraulic shock absorber, the oil chamber 19 is connected to a tank serving as a reservoir disposed outside the cylinder 3. The suspension spring 14 is interposed between the upper end of the cylinder 3 and the upper end cap 20 of the outer tube 1. In a general hydraulic shock absorber, the suspension spring is interposed between the seat on the cylinder 3 side and the seat on the piston rod 15 side.
[0024]
The piston rod 5 is guided through a seal 17 provided at the end of the piston 4 and the cylinder 3, and the seal 17 is composed of a band or ring made of metal, rubber, or synthetic resin that can be expanded or reduced in diameter. ing. The seal 17 may be provided with a lip. For example, the piston rod 5 is guided through the seal 17 provided at the ends of the piston 4 and the cylinder 3, and the seal 17 is a rubber material provided with a lip that can be freely bent. Then, if the diameter is increased or decreased following the surface of the piston rod 5, the lip can also follow and the leakage of hydraulic oil can be prevented.
[0025]
When the hydraulic shock absorber is used as an inverted front fork of a motorcycle, the outer tube 1 is coupled to the vehicle body side, and the inner tube 2 is coupled to the front wheel side axle.
[0026]
On the other hand, when used as a general hydraulic shock absorber without the outer tube 1 and the inner tube 2, the piston rod 5 is coupled to the vehicle body side, and the cylinder 3 is coupled to the axle side.
[0027]
Next, the operation will be described.
[0028]
During the extension operation, the piston rod 5 and the outer tube 1 rise. At this time, the oil in the rod side oil chamber 6, which becomes high pressure, flows out to the anti-rod side oil chamber 7 through the extension side damping valve 9, and the extension side damping valve 9. Generates extensional damping force due to The oil corresponding to the withdrawal volume of the piston rod 5 is introduced from the reservoir 8 into the anti-rod side oil chamber 7 via the port 18 -the oil chamber 19 -the extension side check valve 12. On the other hand, at the time of compression operation, the piston rod 5 and the outer tube 1 descend against the suspension spring 14, and the oil in the anti-rod side oil chamber 7, which becomes high pressure, flows out to the rod side oil chamber 6 through the pressure side check valve 10, The oil corresponding to the intrusion volume of the piston rod 5 flows out from the pressure side damping valve 11 to the reservoir 8 through the oil chamber 19 and the port 18, and a pressure side damping force is generated by the pressure side damping valve 11. When the compression operation of the piston rod 5 proceeds halfway, the conical part 5 c enters the cylinder 3, and the large diameter part 5 b further enters the cylinder 3 while expanding the seal 17. For this reason, the rod intrusion integral increases by an amount corresponding to a large change in the rod diameter corresponding to the conical portion 5c and the large diameter portion 5b, so that the flow rate passing through the compression side damping valve 11 increases and the damping force increases.
[0029]
In this case, the piston rod 5 smoothly passes through the seal 17 by connecting through the conical portion 5c as shown in the figure, and the change of the damping force is smooth and uncomfortable. Further, if the conical portion 5c is set longer, the compression side damping force gradually increases according to the intrusion stroke of the piston rod 5, and the damping force can be increased depending on the stroke position. Accordingly, in the latter half of the stroke of the compression operation, in other words, the compression side damping force can be increased near the time of the most compression, so that the bottoming phenomenon can be suppressed. Further, when switching from the most compressed state to the extension operation, the outer diameter of the piston rod 5 is reduced, so that the extension side damping force is small and the recovery is quick, and the absorption capacity is high even if there is a repeated input action.
[0030]
FIG. 2 shows another embodiment of the present invention, which is used as a rear cushion unit of a motorcycle.
[0031]
The rear cushion unit includes a shock absorber main body A and a tank B serving as a reservoir communicating with the shock absorber main body A.
[0032]
As in the case of FIG. 1, the shock absorber main body A has a piston rod 25 movably inserted into a cylinder 23 via a piston 24, and the piston 24 is inserted into the cylinder 23 with a rod-side oil chamber 26 and an anti-rod-side oil chamber. 27, the two oil chambers 26, 27 communicate with each other via a first extension side valve 28 provided on the piston 24 and a first pressure side valve 29, and the anti-rod side oil chamber 27 is provided on the partition wall 30. A suspension spring 35 in which a piston rod 25 is interposed between spring seats 37 is communicated with a tank B composed of a gas chamber 33 and an oil chamber 34 via a second extension side valve 31 and a second pressure side valve 32. It is urged | biased by the extending direction always through.
[0033]
As in the embodiment of FIG. 1, the piston rod 25 is formed into a small diameter portion 25 a, a conical portion 25 c, and a large diameter portion 25 b near the piston 24, and is movably inserted into the cylinder 23 via the piston 24 and the seal 38. Has been.
[0034]
The expansion and contraction operation of the piston rod 25 and the operation and effect thereof are the same as those in the embodiment of FIG.
[0035]
【The invention's effect】
The present invention has the following effects.
[0036]
(1) According to the inventions of claims 1 and 2, the piston rod is composed of a small-diameter portion having an arbitrary length in the vicinity of the piston and a large-diameter portion connected to the small-diameter portion via a conical portion that expands upward. Since it comprised, when the compression operation of a piston rod progressed to the middle, a cone part will penetrate | invade in a cylinder, and a large diameter part will penetrate | invade in a cylinder, expanding a seal | sticker. For this reason, the rod intrusion integral is increased by an amount corresponding to a large change in the rod diameter corresponding to the conical portion and the large diameter portion, so that the flow rate passing through the compression side damping valve increases and the compression side damping force can be increased. In other words, the damping force can be increased depending on the position of the compression stroke of the piston rod.
[0037]
(2) Similarly , because the rod diameter of the piston rod changes so as to gradually increase along the conical outer peripheral surface via the conical portion, the compression side damping force changes smoothly, and the compression side damping force changes during the compression operation. Even so, it will not give the rider any discomfort or discomfort.
[0038]
(3) Similarly, only the outer diameter of the piston rod is changed, and no special structure is added to the valve mechanism, so the overall structure is simple, the number of parts is low, the cost is low, the workability is Assembly can be improved.
[0039]
(4) Similarly, the valve characteristics are flexible because a damping force depending on the compression stroke position can be obtained regardless of the gas spring characteristics and suspension spring characteristics.
[0040]
(5) Similarly, the seal expands and contracts in response to changes in the rod diameter when the piston rod enters and exits, so it can always slide in contact with the outer peripheral surface of the piston rod, and hydraulic oil in the cylinder leaks to the outside. Can be prevented.
[0041]
(6) Similarly, when the seal is made of a rubber material having a lip, the diameter of the oil is increased or reduced concentrically in response to a change in the outer diameter of the piston rod, so that the hydraulic oil can be further leaked to the outside. It can be done reliably.

[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional front view of a hydraulic shock absorber according to an embodiment of the present invention.
FIG. 2 is a schematic longitudinal sectional view of a hydraulic shock absorber according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Car body side outer tube 2 Axle side inner tube 3, 23 Cylinder 4, 24 Piston 5, 25 Piston rod 5a, 25a Small diameter part 5b, 25b Large diameter part 5c, 25c Conical part 6, 26 Rod side oil chamber 7, 27 Rod side oil chamber 8 Reservoir 9, 28 Extension side damping valve 10, 29 Pressure side check valve 11, 31 Pressure side damping valve 12, 32 Extension side check valve 13 Base valve 14, 35 Suspension spring 17 Seal

Claims (2)

A piston rod is movably inserted into the cylinder via a piston, and the piston rod is guided through a seal provided at the end of the cylinder. The piston is inserted into the cylinder in the rod side oil chamber and the anti-rod side oil chamber. The two oil chambers communicate with each other via an extension side damping valve and a pressure side check valve provided on the piston, and the anti-rod side oil chamber passes through a base valve composed of a pressure side damping valve and an extension side check valve. In a hydraulic shock absorber that communicates with the reservoir and the piston rod is constantly urged in the extending direction via a suspension spring, the piston rod has a small-diameter portion of an arbitrary length near the piston and the small-diameter portion upward. towards constituted by a large diameter portion which is continuously provided with a conical portion which increases in diameter, it is made of rubber material having the seal diameter or diameter can be a band or ring, or a telescopic lip, The tapered part and the large diameter portion from the middle during contraction operation is due to the increase of the rod intrusion volume upon entering the cylinder to increase the passing flow of working oil passing through the compression side damping valve, a compression stroke of the piston rod A hydraulic shock absorber, wherein the damping force by the compression side damping valve is increased depending on the position of the hydraulic shock absorber. The axle side inner tube is slidably inserted into the vehicle body side outer tube, the cylinder is erected at the center of the bottom of the inner tube, and the piston rod is movably inserted into the cylinder via the piston. Guided through a seal provided at the end of the cylinder, the piston partitions the rod side oil chamber and the anti-rod side oil chamber in the cylinder, and the two oil chambers are the extension side damping valve and pressure side check provided on the piston. The non-rod side oil chamber communicates with the reservoir via a base valve consisting of a compression side damping valve and an extension side check valve, and the piston rod is always urged in the extending direction via a suspension spring. hydraulic shock absorber at a piston rod continuously provided and the small diameter portion of arbitrary length of the piston near a conical portion whose diameter increases toward the small diameter portion upwardly are Is constituted by a large diameter portion, the seal diameter or diameter can be a band or ring, or retractable is configured lip rubber material having the above from the middle of the time compressed working large diameter portion in the cylinder Increases the flow rate of hydraulic oil passing through the compression side damping valve due to the increase in the rod entry volume when it enters the cylinder, and increases the damping force by the compression side damping valve depending on the compression stroke position of the piston rod. A hydraulic shock absorber characterized by that.

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