JPH0719642U - Vehicle shock absorber - Google Patents

Abstract

(57) [Summary] [Object] To provide a damping force variable type vehicle shock absorber capable of smoothly changing the damping force. [Structure] Inside the damper cylinder 11, main fluid chambers 12, 13
Housing 2 provided integrally with the piston 14 for partitioning
7, spools 32 and 33 that are slidably fitted in the housing 27 to partition the inside of the housing 27 into two sub-fluid chambers 34 and 38, one sub-fluid chamber 34 and one main fluid chamber 12 Communicating passages 35 to 37 communicating with each other, and a communicating passage 3 communicating with the other sub-fluid chamber 38 and the main fluid chamber 13.
9, a non-linear member that is interposed between the spools 32 and 33 and the housing 27 to hold the spools 32 and 33 in the neutral position and to increase the spring constant as the displacement amount of the spools 32 and 33 increases. Spring member 4 having spring characteristics
It has 0 and 41.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a damping force variable type vehicle shock absorber capable of smoothly changing the damping force.

[0002]

[Prior art]

 BACKGROUND OF THE INVENTION A damper (hereinafter referred to as a shock absorber) that constitutes a part of a suspension device that is assembled between a vehicle body and wheels of an automobile or the like is used to reduce the impact of an irregular road surface and the vibration of the vehicle body to reduce the occupant's riding time. In addition to improving comfort, it protects the load and enhances the ground contact of the tire to ensure steering stability.The damper cylinder filled with fluid such as oil and the inside of this damper cylinder It is generally of a cylindrical shape having a piston rod to which a piston that slides is fixed.

Generally, in such a shock absorber, a fluid is flown between two fluid chambers in a damper cylinder partitioned by a piston through an orifice passage formed in the piston as the wheel moves up and down. Although it goes back and forth, the resistance of the fluid flowing through the orifice passage at this time damps the vibration that accompanies the vertical movement of the wheel.

Further, in such a shock absorber, a free piston, which makes an inertial motion with respect to a vertical movement of the piston, is incorporated in a piston rod, and the inertial motion of the free piston is used to cause a space between two fluid chambers in a damper cylinder. A variable damping force type in which the rate of change of the damping force with respect to the amount of movement of the piston is appropriately adjusted by adjusting the movement of the fluid in the piston independently of the piston described above is, for example, Japanese Patent Publication No. 47-37759. It is proposed in the official gazette and Japanese Examined Patent Publication No. 44-2008.

In the case of the shock absorber disclosed in Japanese Patent Publication No. 47-37759, a small damping force is generated until the floating piston contacts the stopper against the spring force of the restoring spring. A large damping force is generated when the floating piston comes into contact with the stopper.

Further, in the case of the shock absorber disclosed in Japanese Patent Publication No. 44-29808, the communication hole formed in the sleeve valve that strokes against the spring force of the valve spring communicates with the communication hole formed in the lock nut. While in the state, a small damping force is generated, and a large damping force is generated when the communication hole of the three-way valve and the communication hole of the lock nut are moved to the non-communication state.

[0007]

[Problems to be solved by the device]

 In the conventional damping force variable type shock absorber disclosed in Japanese Patent Publication No. 47-37759, the displacement of the piston and the floating piston is only because the spring force of the restoring spring is biased to the floating piston. As shown in Fig. 3 in which the relationship between the amount and the damping force is shown by a chain double-dashed line, the state in which a small damping force is generated and the state in which a large damping force is generated suddenly switch. As a result, the riding comfort of the vehicle is deteriorated, and if the switching of the damping force occurs during steering of the vehicle, the behavior of the vehicle becomes unstable and the driver may feel uncomfortable with the steering. It was

In this respect, the conventional damping force variable type shock absorber disclosed in Japanese Patent Publication No. 44-29088 is formed in the communication hole formed in the sleeve valve and the lock nut as the sleeve valve moves. As a result, there is a displacement with the communication hole, and these passages are constricted.Therefore, a restraining force is generated against the movement of the sleeve valve, and the relationship between the displacement amount of the piston and the sleeve valve and the damping force is indicated by the broken line. As shown in FIG. 3, which is represented, there is an advantage that the change of the damping force is performed more smoothly than that of the above-mentioned Japanese Patent Publication No. 47-37759. However, as a practical matter, a smooth increase in the restraining force against an increase in the displacement of the sleeve valve due to the shape of the communication hole, etc. can hardly be expected, and as in the previous example, a small damping force is generated. , Switching to a state where a large damping force occurs occurs relatively rapidly. As a result, the riding comfort of the vehicle is deteriorated, and if the switching of the damping force occurs during the steering of the vehicle, the behavior of the vehicle becomes unstable and the driver may feel uncomfortable with the steering. It was

Moreover, the above-described conventional shock absorber has a structure in which the damping force changes only in the direction in which the shock absorber extends, and the damping force does not change in the direction in which the shock absorber contracts.

[0010]

[The purpose of the device]

 An object of the present invention is to provide a damping force variable type vehicle shock absorber that can smoothly change the damping force.

[0011]

[Means for Solving the Problems]

 A shock absorber for a vehicle according to the present invention comprises a damper cylinder having a shock absorbing fluid filled therein, a piston rod slidably passing through one end of the damper cylinder, and one end of which is located in the damper cylinder. A piston integrally fixed to one end of the piston rod and slidably fitted in the damper cylinder to partition the damper cylinder into two main fluid chambers; In a vehicle shock absorber having a passage communicating with two main fluid chambers and a damping force generating means provided in the passage for limiting the flow of the fluid in the passage, the shock absorber for a vehicle is integrally provided on one end side of the piston rod. And a cup-shaped spool that is fitted in the housing in a sliding manner to partition the interior of the housing into two sub-fluid chambers. Between the sub-fluid chamber and the one main fluid chamber, a communication passage that communicates the other sub-fluid chamber and the other main fluid chamber, and between the spool and the housing. The present invention is characterized in that it is provided with a spring member which is interposed and holds the spool in a neutral position and which has a non-linear spring characteristic in which a spring constant increases with an increase in displacement of the spool. .

[0012]

[Action]

 According to the present invention, when the piston moves to one main fluid chamber side, the inertial force displaces the spool to the other sub fluid chamber side against the spring force of the spring member. As the amount of displacement of the spool increases, the resistance to the displacement of the spool gradually increases due to the spring member having a non-linear spring characteristic, and the moving speed of the spool becomes slow. Next, the damping force generating means provided in the passage communicating with the two main fluid chambers partitioned by the piston acts and flows from one main fluid chamber to the other main fluid chamber through the passage. As a result of the restriction of the fluid flow, the damping force smoothly changes from a small state to a large state.

Similarly, when the piston moves toward the other main fluid chamber, the inertial force displaces the spool toward the one sub fluid chamber against the spring force of the spring member. As the amount of displacement of the spool increases, the resistance to displacement of the spool gradually increases due to the spring member having a non-linear spring characteristic, and the moving speed of the spool becomes slow. Then, the damping force generating means provided in the passage communicating with the two main fluid chambers partitioned by the piston acts, and the flow of the fluid flowing from one main fluid chamber to the other main fluid chamber through the passage. As a result, the damping force smoothly transitions from a small damping force to a large damping force.

[0014]

【Example】

 FIG. 1 shows a fracture structure of a main part of an embodiment of a vehicle shock absorber according to the present invention. That is, the buffer of the present embodiment is interposed between a swinging arm (not shown) that supports an axle (not shown) and a body frame (not shown) that supports the swinging arm and the like while being suspended from the body frame together with the axle. In the device, the lower end of a damper cylinder 11 is fixed to the above-described swing arm or the like via a bracket (not shown). The damper cylinder 11 has an interior filled with a buffer fluid such as hydraulic oil as an upper chamber. A piston 14 which is partitioned into 12 and a lower chamber 13 is slidably accommodated. An annular rod guide (not shown) that slidably holds the piston rod 15 is attached to the upper end of the damper cylinder 11. The rod guide and the piston 14 make the piston rod 15 coaxial with the damper cylinder 11. Holding in a shape.

A stopper 16, a collar 17, an upper reed valve 18, a piston 14, a lower reed valve 19, and an auxiliary reed valve 20 are arranged at the lower end of a piston rod 15 whose upper end is connected to a vehicle body (not shown). Then, the collar 21 is fitted, and these are integrally fitted to the piston rod 15 by the nut 22 screwed into the lower end of the piston rod 15. Further, the above-mentioned piston 14 is provided with an orifice passage 23 capable of communicating the upper chamber 12 and the lower chamber 13 with each other via the upper reed valve 18, and with the upper chamber 12 with the lower reed valve 19 and the auxiliary reed valve 20. An orifice passage 24 that can communicate with the chamber 13 is formed.

That is, in a region where the moving speed of the piston 14, which moves up and down relatively largely with respect to the damper cylinder 11 following the unevenness of the road surface, is relatively slow, the orifice passages 23 and 24 are reed valves 18 to 20. Since each is in the closed state, the increasing rate of the damping force tends to be large relative to the increasing rate of the moving speed of the piston 14. However, when the relative vertical movement speed of the piston 14 with respect to the damper cylinder 11 exceeds a preset value, the reed valves 19 to 20 are elastically deformed to open the orifice passages 23 and 24. The rate of increase of the damping force tends to be smaller than the rate of increase of the moving speed, and the characteristics as a general shock absorber known from the past can be obtained.

On the other hand, an upper end portion of a spool housing 27 in which an upper sealing plate 25 and a lower sealing plate 26 are fitted to both upper and lower end portions is integrally joined to a lower end of the nut 22. An outer peripheral edge portion of an annular spring receiver 30 is held between a pair of upper and lower cylindrical spacers 28 and 29 which are integrally fitted inside. That is, the upper spacer 28 is interposed between the upper sealing plate 25 and the spring bearing 30, and the lower spacer 29 is interposed between the lower sealing plate 26 and the spring bearing 30. A pair of upper and lower spools 32 and 33 slidably fitted to the spacers 28 and 29 are integrally attached to both upper and lower ends of a spool shaft 31 which slidably penetrates the spring receiver 30. . Further, in the upper damper chamber 34 formed between the upper spool 32 and the upper sealing plate 25, the communication passages 35 and 36 formed in the piston rod 15 and the orifice formed in the central portion of the upper sealing plate 25. The upper chamber 12 is in communication via 37. Similarly, a lower damper chamber 38 formed between the lower spool 33 and the lower sealing plate 26 is in communication with the lower chamber 13 via an orifice 39 formed in the central portion of the lower sealing plate 26. ing.

An annular rubber-like elastic body 40 made of synthetic rubber, synthetic resin, or the like is interposed between the upper spool 32 and the spring receiver 30, and similarly, the lower spool 33 is provided. An annular rubber-like elastic body 41 made of synthetic rubber, synthetic resin, or the like is also interposed between and the spring receiver 30. As shown in FIG. 2, which shows the relationship between the amount of compressive deformation of these rubber-like elastic bodies 40, 41 for holding the spools 32, 33 in the neutral state and their spring constants, these rubber-like elastic bodies 40, 41 are compressed. The spring constant has a non-linear spring characteristic in which the spring constant rapidly increases in a quadratic curve as the amount of deformation increases, and these spring constants are set to be smaller than the spring constants of the reed valves 18 to 20 described above. ing. Therefore, in a region where the reed valves 18 to 20 are not elastically deformed, the upper spool 32 and the lower spool 32 are adapted to vertically move in the spool housing 27 in response to a small vertical movement of a wheel (not shown). There is.

Therefore, when the piston 14 moves up and down relative to the damper cylinder 11 with a short stroke along with the piston cylinder 15 following a minute unevenness of the road surface, the spools 32 and 33 are spooled by inertia due to inertia. It moves up and down in the housing 27 in reverse.

For example, in the process in which the piston 14 rises with respect to the damper cylinder 11, the spools 32 and 33 descend in the spool housing 27 against the spring force of the rubber-like elastic body 41, and the upper chamber 12 side A part of the working fluid of the above is introduced into the upper damper chamber 34 through the communication passages 35 and 36 and the orifice 37, while the working fluid in the lower damper chamber 38 is pushed out from the orifice 39 to the lower chamber 13 side, A damping force is generated according to the resistance of the working fluid passing through 37 and 39 and the compression resistance of the rubber-like elastic body 41. The compression resistance force of the rubber-like elastic body 41 rapidly increases as the descending amount of the spools 32 and 33 increases, and the descending of the spools 32 and 33 is gradually restrained. As a result, the piston 14 and the spool As shown by the solid line in FIG. 3 showing the relationship between the displacement amount of 32 and 33 and the damping force, a smooth change in the damping force can be obtained.

Similarly, in the process in which the piston 14 descends with respect to the damper cylinder 11, the spools 32, 33 rise in the spool housing 27 against the spring force of the rubber-like elastic body 40, and the lower chamber 13 While a part of the working fluid on the side is introduced into the lower damper chamber 38 through the orifice 39, the working fluid in the upper damper chamber 34 is pushed out from the orifice 37 to the upper chamber 12 side through the communication passages 36 and 35. At this time, a damping force corresponding to the resistance of the working fluid passing through the orifices 37 and 39 and the compression resistance of the rubber elastic body 40 is generated. The compression resistance of the rubber-like elastic body 40 rapidly increases as the amount of rise of the spools 32, 33 increases, and the rise of the spools 32, 33 is gradually restrained. As a result, as in the previous case, It is possible to obtain a smooth change in damping force as shown by the solid line in 3.

Incidentally, with respect to the movement of the piston 14 beyond the stroke ends of the spools 32 and 33, the above-described reed valves 18 to 20 operate and a high damping force is obtained.

As described above, in the rubber-like elastic bodies 40 and 41 functioning as the spring members in the present invention, the relative amount of vertical movement of the spools 32 and 33 with respect to the spool housing 27 increases from the neutral state shown in FIG. Accordingly, as long as it has a characteristic that the resistance force against the movement of the spools 32 and 33 increases rapidly, not only the rubber-like elastic bodies 40 and 41 described above but also rubbers filled with fluid inside It is also possible to employ a linear elastic body, an unequal pitch coil spring, or a coil spring whose wire diameter or coil diameter changes.

For example, the sectional structure of another embodiment of the portion of the spool housing 27 as shown in FIG. 4 can be adopted. That is, the upper and lower ends of the inner cylinder 42 integrally fitted to the inside of the spool housing 27 in which the upper and lower sealing plates 25 and 26 are fitted to the upper and lower end portions are the upper and lower sealing plates 25 and 26. Are in contact with each other. A spool 43 having a cup-shaped cross section that divides the inner cylinder 42 into an upper damper chamber 34 and a lower damper chamber 38 is slidably fitted in the inner cylinder 42. The upper damper chamber 34 accommodates a taper coil spring 44 having a smaller wire diameter toward the lower end side, and the lower damper chamber 38 accommodates a conical coil spring 45 having a larger coil diameter toward the lower end side. Each of the springs 44 and 45 has a non-linear spring characteristic as shown in FIG. The members having the same functions as those of the previous embodiment shown in FIG. 1 are designated by the same reference numerals.

As a result, a smooth change of the damping force as shown by the solid line in FIG. 3 is produced in the same manner as in the previous embodiment with respect to the relative vertical movements of the damper cylinder 11 and the piston 14 that follow the unevenness of the road surface. Obtainable. Further, in this embodiment, since the coil springs 44 and 45 are housed in the damper chambers 34 and 38 respectively and the single spool 43 and the like are adopted, the number of parts can be reduced as compared with the previous embodiment. In addition, the spool housing 27 can be made shorter.

[0026]

[Effect of device]

 According to the vehicle shock absorber of the present invention, the spool is incorporated in the housing integrated with the piston, and the spring having a non-linear spring characteristic in which the spring constant increases between the spool and the housing as the displacement of the spool increases. Since a member is interposed, the restraining force against the movement of the spool gradually increases as the spool approaches its stroke end due to inertia, and as a result, the damping force changes smoothly with the movement of the spool. Can be realized.

Further, since the spool is moved by inertia when the shock absorber is compressed, it is possible to gradually change the damping force even during the compression operation of the shock absorber.

[Brief description of drawings]

FIG. 1 is a cutaway view showing main parts of an embodiment of a vehicle shock absorber according to the present invention.

FIG. 2 is a graph schematically showing a relationship between a displacement amount of a rubber-like elastic body and a spring constant in the present embodiment shown in FIG.

FIG. 3 shows the relationship between the displacement amount of the spool and the damping force in the present embodiment shown in FIG. 1, and the relationship between the displacement amount of the free piston and the damping force in the conventional damping force variable type vehicle shock absorber. It is a graph showing typically.

FIG. 4 is a cutaway view showing a main part of another embodiment of the vehicle shock absorber according to the present invention.

[Explanation of symbols]

 11 Damper Cylinder 12 Upper Chamber 13 Lower Chamber 14 Piston 15 Piston Rod 16 Stopper 17 Collar 18 Upper Reed Valve 19 Lower Reed Valve 20 Auxiliary Reed Valve 21 Collar 22 Nut 23, 24 Orifice Passage 25 Upper Seal Plate 26 Lower Seal Plate 27 Spool Housing 28 upper spacer 29 lower spacer 30 spring bearing 31 spool shaft 32 upper spool 33 lower spool 34 upper damper chamber 35, 36 communication passage 37 orifice 38 lower damper chamber 39 orifice 40, 41 rubber-like elastic body 42 inner cylinder 43 spool 44 taper coil spring 45 conical coil spring

Claims (1)

[Scope of utility model registration request] 1. A damper cylinder in which a buffer fluid is filled, a piston rod slidably penetrating one end of the damper cylinder and one end of which is located in the damper cylinder, and a piston rod of the piston rod. A piston integrally fixed to one end side and slidably fitted in the damper cylinder to partition the inside of the damper cylinder into two main fluid chambers; and the two main fluid chambers formed in the piston. In a shock absorber for a vehicle having a passage communicating with the piston rod and a damping force generating unit provided in the passage for limiting the flow of the fluid in the passage, and a housing integrally provided on one end side of the piston rod. A spool having a cup shape that is slidably fitted in the housing to partition the interior of the housing into two sub-fluid chambers, and one of the sub-fluid chambers A communication passage that communicates with the main fluid chamber, a communication passage that communicates the other sub fluid chamber with the other main fluid chamber, and a neutral passage that is interposed between the spool and the housing. A shock absorber for a vehicle, comprising: a spring member having a non-linear spring characteristic which is held in a position and whose spring constant increases with an increase in displacement of the spool.