JP2002127727A - Suspension device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control rolling in turning without deteriorating a riding comfort in a suspension device for a vehicle. SOLUTION: An attenuation adjustment type oil hydraulic buffer 1 attached on a left and right wheel is connected mutually by a tube route 2 and by a different pressure between these cylinders under room 3b, a spool 25 is moved to adjust the attenuation. In the tube route 2, a high frequency filter 39 is installed. In going straight ahead, when a left and right piston rod 7 strokes at the same phase, the attenuation is made smaller to improve a riding comfort, and in turning when it strokes at the opposite phase, the attenuation is made larger to control the rolling. When the piston rod 7 strokes at the opposite phase by a small amplitude frequency under a spring, a magnetic fluid 42 of the high frequency filter 39 moves within the limit of a magnetic field of a permanent magnet 43 and viscosity of the magnetic fluid increases and the attenuation is made smaller by hindering the movement of the spool 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension device for a vehicle such as an automobile.

[0002]

2. Description of the Related Art In a suspension system for an automobile, for example, in a straight running state, generally, a smaller damping force of a hydraulic shock absorber is more likely to absorb vibrations, so that the riding comfort is good, and acceleration and deceleration states and turning are also good. In this state, the greater the damping force of the hydraulic shock absorber, the more the posture change such as pitching and rolling of the vehicle body is suppressed, so that the steering stability is improved. Therefore, conventionally, using a damping force adjustable hydraulic shock absorber capable of adjusting the damping force, an actuator for switching the damping force, a controller for controlling the operation of the actuator, and various sensors for detecting the acceleration of the vehicle body, etc. 2. Description of the Related Art There is known a suspension control device that improves ride comfort and steering stability by appropriately adjusting a damping force according to a road surface condition, a running condition, and the like.

[0003] This type of suspension control device requires expensive electronic equipment such as a controller and an actuator, and has a problem in that costs are required in order to ensure the reliability thereof. Therefore, for example, the hydraulic shock absorbers mounted on the left and right wheels of the vehicle are connected to each other by a pipeline, and when a differential pressure is generated in the hydraulic fluid in the left and right hydraulic shock absorbers, the spool provided inside the piston rod is moved. A suspension device has been proposed in which the damping force is increased to suppress rolling of the vehicle body during turning of the vehicle (see JP-A-10-213171).

[0004]

In the above-mentioned conventional suspension device in which the left and right hydraulic shock absorbers are connected, even when the left and right wheels pass through a protrusion on the road surface even when the vehicle is not turning.
Even when a differential pressure is generated in the left and right hydraulic shock absorbers due to unsprung high-frequency vibrations, there is a problem that the riding comfort deteriorates because the damping force increases.

Therefore, an orifice or the like is provided in a conduit connecting the left and right hydraulic shock absorbers to attenuate the transmission of the differential pressure between the left and right hydraulic shock absorbers due to unsprung high-frequency vibration, thereby preventing deterioration in ride comfort. are doing.

However, the transmission of the differential pressure between the left and right hydraulic shock absorbers due to the low frequency vibration on the spring due to the rolling of the vehicle body at the time of turning is allowed, and the transmission of the differential pressure due to the high frequency vibration under the spring is reliably attenuated. It is very difficult to determine such an optimal orifice diameter.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to provide a suspension device capable of effectively suppressing a change in posture of a vehicle body such as rolling without deteriorating ride comfort. Aim.

[0008]

According to a first aspect of the present invention, there is provided a suspension apparatus comprising: a cylinder filled with an oil liquid; and a piston slidably fitted in the cylinder. A piston rod having one end connected to the piston and the other end extending out of the cylinder;
A damping system comprising: an oil passage through which oil flows by sliding the piston; and a damping force generating mechanism that controls the flow of the oil in the oil passage to generate a damping force and adjusts the damping force. The force-adjustable hydraulic shock absorber is mounted on the front and rear or left and right wheels of the vehicle, respectively, and the oil chambers in the front and rear or left and right damping force-adjustable hydraulic shock absorbers are communicated with each other by a pipeline,
The damping force generating mechanism is switched according to the movement of the oil liquid in the pipeline caused by the pressure difference between the oil chambers, so that the stroke of the piston rod of the front-back or left-right damping force-adjustable hydraulic shock absorber is reduced. When the phase is the same, the damping force is reduced, and when the phase is reversed, the damping force is increased.Furthermore, a resistance means is provided that applies resistance only to movement of the oil liquid in the pipe within a predetermined range. It is characterized by having. With this configuration, when the piston rods of the front-rear or left-right damping-force-adjusting hydraulic shock absorber stroke in the same phase, the pressures in the cylinder chambers of the front-rear or left-right damping-force-adjusting shock absorber become substantially equal. Since the movement of the oil liquid in the pipeline is small, the damping force is small, and when the stroke is performed in the opposite phase, a differential pressure is generated in the cylinder chamber of the front-back or left-right damping force-adjustable hydraulic shock absorber. Since the movement of the oil liquid in the road increases, the damping force increases. When the piston rod is stroked in the opposite phase, the movement of the oil liquid in the pipeline is within a predetermined range for high-frequency vibration with a relatively small stroke, and the movement of the oil liquid is suppressed by the resistance means. For low-frequency vibrations in which the stroke of the piston rod is relatively large, the movement of the oil liquid in the pipeline exceeds a predetermined range and the resistance of the resistance means does not act. Strength increases. In the suspension device according to claim 2, in the configuration according to claim 1, the resistance means includes a magnetic fluid contained between a pair of free pistons slidably fitted in the pipeline, and the magnetic fluid. Magnetic field generating means for applying a magnetic field to the fluid. With this configuration, the viscosity of the magnetic fluid increases within the range of the magnetic field of the magnetic field generating means, causing a large resistance to the movement of the oil liquid in the pipeline. As a result, the viscosity decreases and the resistance to the movement of the oil liquid in the pipeline decreases. Also,
According to a third aspect of the present invention, in the configuration of the first aspect, the resistance means includes a cylinder portion formed in the pipe, and a slidably fitted inside the cylinder portion. A free piston defined in the chamber, a throttle passage communicating the two chambers in the cylinder with each other, and an axial groove disposed on both sides of the free piston at a neutral position on the inner wall of the cylinder. It is characterized by including. With this configuration, when the movement of the oil liquid in the pipeline is small, the free piston moves near the neutral position together with the oil liquid in the pipeline.
A large resistance is received through the throttle passage. Also, when the movement of the oil liquid in the pipe is large, the free piston moves beyond the vicinity of the neutral position together with the oil liquid in the pipe, and the two chambers in the cylinder communicate with each other via the groove. The oil liquid flows through the groove to reduce the resistance.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, a suspension device according to the present embodiment includes two damping force-adjustable hydraulic shock absorbers 1 (hereinafter, referred to as shock absorbers 1) mounted on left and right wheels (not shown) of a vehicle such as an automobile. ) Are connected to each other by a pipe 2.

As shown in FIGS. 1 and 2, the shock absorber 1 has a double-cylinder structure in which an outer cylinder 4 is provided
A reservoir 5 is formed between 3 and the outer cylinder 4. Cylinder 3
A piston 6 is slidably fitted therein, and the piston 6 defines the inside of the cylinder 3 into two chambers, a cylinder upper chamber 3a and a cylinder lower chamber 3b. One end of a hollow piston rod 7 is connected to the piston 6, and the other end of the piston rod 7 is inserted through a rod guide 8 and an oil seal 9 attached to the upper ends of the cylinder 3 and the outer cylinder 4 to be externally connected. Has been extended to. At the other end of the cylinder, a base valve 10 that connects the cylinder lower chamber 3a and the reservoir 5 is provided. An oil liquid is sealed in the cylinder 3, and an oil liquid and a gas are sealed in the reservoir 5.

The piston 6 is provided with an extension passage 11 and a contraction passage 12 which communicate between the cylinder upper and lower chambers 3a and 3b. At both ends of the piston 6, an extension side damping force generation mechanism 13 and a contraction side damping force generation mechanism 14 are provided. The piston 6, the extension-side damping force generating mechanism 13, and the contraction-side damping force generating mechanism 14 are integrally connected by screwing a nut 16 to a distal end of a substantially cylindrical piston bolt 15 inserted therethrough. . The piston rod 7 is screwed to the base end of the piston bolt 15.

The extension side damping force generating mechanism 13 includes a disk valve 17, a fixed member 18, and a movable member 19, and a back pressure chamber 20 is formed by these. The disc valve 17 generates a damping force by controlling the flow of the oil liquid in the extension side passage 11 in accordance with the opening degree. The back pressure chamber 20 adjusts the valve opening pressure by causing the internal pressure to act on the back side of the disc valve 17.
The extension-side oil passage 11 is communicated with a back pressure chamber 20 by a fixed orifice 21 provided in the disc valve 17, and the back pressure chamber 20 is connected to a port 2 provided on a side wall of the piston bolt 15.
It communicates with the cylinder lower chamber 3b via a check valve 24 provided on the fixing members 18 and 23. In the piston bolt 15, a spool 25 for adjusting a flow passage area between the ports 22, 23 is fitted. And port 2 by spool 25
The damping force is adjusted by changing the flow path area between 2 and 23, thereby changing the pressure of the back pressure chamber 20 and changing the valve opening pressure of the disc valve 17 to adjust the damping force characteristics. .

The compression side damping force generating mechanism 14 includes a disk valve 26, a fixed member 27, and a movable member 28, and a back pressure chamber 29 is formed by these. The disc valve 26 generates a damping force by controlling the flow of the oil liquid in the contraction side passage 12 according to the degree of opening. The back pressure chamber 29 adjusts the valve opening pressure by applying the internal pressure to the back side of the disc valve 26.
The extension-side oil passage 12 is communicated with a back pressure chamber 29 by a fixed orifice 30 provided in the disc valve 26, and the back pressure chamber 29 is further connected to a port 3 provided on a side wall of the piston bolt 15.
It communicates with the cylinder upper chamber 3a via a check valve 33 provided on the fixing members 27. The damping force is adjusted by changing the flow path area between the ports 31 and 32 by the spool 25 shared with the extension side damping force generating mechanism 13 and the spool 25, thereby changing the pressure of the back pressure chamber 29, and The damping force characteristic is adjusted by changing the valve opening pressure of the valve 26.

The spool 25 is normally held at the illustrated neutral position by return springs 34A and 34B disposed on both sides of the spool 25, and is provided between the ports 22 and 23 of the extension side damping force generating mechanism 13 and the compression side damping mechanism. The flow path between the ports 31 and 32 of the force generating mechanism 14 is both open. Then, by moving downward from the neutral position in the figure, the port 22 of the extension side damping force generation mechanism 13
By closing the flow path between 23 and moving upward in the figure, the flow path between the ports 31 and 32 of the contraction-side damping force generating mechanism 14 is closed.

An oil chamber 35 at one end of the spool 25 in the piston bolt 15 communicates with the cylinder lower chamber 3b through an oil passage 36, and an oil chamber 37 at the other end is provided inside the hollow piston rod 7. The oil passage 38 is formed to communicate with the oil passage 38. The oil passages 38 of the piston rods 7 of the shock absorbers 1 mounted on the left and right wheels are communicated with each other by the pipe 2.

A high frequency filter 39 (resistance means) is provided in the pipe 2.
Is provided. As shown in FIG. 3, the high frequency filter 3
In 9, a cylinder portion 40 is provided in the middle of the pipeline 2, and a pair of free pistons 41 are slidably fitted in the cylinder portion 40. A magnetic fluid is provided between the pair of free pistons 41.
42 are filled. The magnetic fluid 42 is a fluid whose viscosity is reversibly changed by the action of a magnetic field, and has a property that the viscosity is small when no magnetic field is applied and the viscosity is increased by applying a magnetic field. It is.

A permanent magnet 43 is attached to the outer periphery of the cylinder section 40. The permanent magnet 43 is arranged so as to be located at the axial center of the magnetic fluid 42 between the free pistons 41 in a state where the spools of the left and right shock absorbers 1 are in the neutral position.

Next, the operation of the embodiment constructed as described above will be described. If the vehicle is in a straight line,
The piston rods 7 of the left and right shock absorbers 1 stroke in the same phase (in-phase) (at the same time, expand and contract in the same direction) with respect to the vertical movement of (spring up).
The pressure in 3b will be approximately equal. As a result, the pressure acting on one end of the spool 25 via the oil passage 36 and the oil chamber 35 becomes equal, so that the spool 25 does not move from the neutral position. As a result, the damping force of the left and right shock absorbers 1 is reduced on both the extension side and the contraction side, and the unsprung vibration due to the unevenness of the road surface or the like is absorbed, and a good ride comfort can be obtained.

When the vehicle is in a turning state, the piston rods 7 of the left and right shock absorbers 1 stroke in opposite phases (opposite phases) with respect to the rolling of the vehicle body (expanding and contracting in opposite directions at the same time). That is, at the time of turning, the piston rod 7 of the outer shock absorber 1 is shortened, and the piston rod 7 of the inner shock absorber 1 is extended.
The cylinder lower chamber 3b is pressurized by the shortening of the piston rod 7, and the cylinder lower chamber 3b is depressurized by the extension of the piston rod 7 in the shock absorber 1 inside the turning. As a result, in the left and right shock absorbers 1, a differential pressure is generated in the pressure of the oil liquid acting on one end of the spool 25 via the oil passage 36 and the oil chamber 35, and in the shock absorber 1 on the outer side of the turning (shortening side), The spool 25 moves upward in the figure, and the port 3 of the compression-side damping force generation mechanism 14
1 and 32, the damping force on the compression side increases, and in the shock absorber 1 on the inner side of rotation (extension side), the spool 25 moves downward in the drawing, and the port 22 of the extension-side damping force generation mechanism 13, Closing 23 increases the damping force on the extension side. As a result, a large damping force can be applied to a change in the posture of the vehicle body, and rolling of the vehicle body can be effectively suppressed, and steering stability can be improved.

The shock absorber 1 generates a damping force having characteristics opposite to each other on the extension side and the contraction side. Therefore, the shock absorber 1 generates a small damping force with respect to a posture change in a direction in which the vehicle body returns to the horizontal position. Thus, the vehicle body can be smoothly returned to the horizontal position.

When the spools 25 of the shock absorber 1 on the left and right sides of the vehicle body move, the magnetic fluid 42 in the cylinder portion 40 moves in the same direction as the oil fluid in the piston rod 7 and the oil fluid in the pipe 2 move. Moving. At this time, the viscosity of the magnetic fluid 42 is increased by the magnetic field of the permanent magnet 43, and a viscous resistance is generated between the magnetic fluid 42 and the inner wall of the cylinder portion 40, thereby providing resistance to the movement of the spool 25.

When the piston rods 7 of the shock absorbers 1 on the left and right sides of the vehicle body are stroked in opposite phases due to unsprung vibration due to irregularities on the road surface, etc., the cylinder lower chamber 3b of the shock absorbers 1 on the left and right sides of the vehicle body
A differential pressure is generated between them, and the differential pressure causes the spool 25 and the magnetic fluid 42 to move. In this case, the unsprung vibration is usually high-frequency vibration with relatively small amplitude,
The amount of movement of the spool 25 and the magnetic fluid 42 is small,
42 moves within the range of the strong magnetic field of the permanent magnet 43. Thus, the magnetic fluid 42 is increased in viscosity by the strong magnetic field of the permanent magnet 43, and exerts a large resistance against the movement of the spool 25. As a result, the spool 25 hardly moves from the neutral position, and the damping force of the shock absorber 1 is maintained at a low damping force on both the extension side and the contraction side, so that the unsprung vibration can be sufficiently absorbed. Good ride comfort can be maintained.

On the other hand, as described above, the shock absorbers on the left and right sides of the vehicle
When the first piston rod 7 strokes in the opposite phase, such a vibration on the spring has a relatively large amplitude and a low frequency, so that the movement amount of the spool 25 and the magnetic fluid 42 is large, and the magnetic fluid 42 Therefore, the magnet moves beyond the range of the strong magnetic field of the permanent magnet 43. As a result, the magnetic fluid 42 reduces the action of the magnetic field of the permanent magnet 43, and the viscosity of the magnetic fluid 42 decreases, so that the resistance to the movement of the spool 25 decreases. as a result,
The spool 25 can be appropriately moved from the neutral position, the damping force of the shock absorber 1 is increased, the rolling of the vehicle body is suppressed, and the steering stability can be improved.

As described above, by the high frequency filter 39,
With respect to the posture change of the vehicle body during turning, by allowing the movement of the spool 25 and appropriately increasing the damping force of the shock absorber 1, it is possible to suppress the rolling of the vehicle body and improve the steering stability, In addition, with respect to unsprung vibration, good riding comfort can be obtained by suppressing the movement of the spool 25 and keeping the damping force of the shock absorber 1 low.

In the above embodiment, the high frequency filter 39
As shown in FIG. 4, step portions 44 are provided at both ends of the cylinder portion 40.
By providing the free piston 41 and the magnetic fluid 42
Stroke range can be limited.

Further, as shown in FIG.
A return spring 45 is provided between the step portions 44 at both ends of each of the free pistons 41 and the respective free pistons 41.
The chambers on both sides of 1 are connected to each other by an oil passage 46, and the oil passage 46
By providing the orifice 47, the free piston 41 and the magnetic fluid 42 can be reliably returned to the neutral position in the normal state. Thus, even if the pressures in the respective reservoirs 5 of the damping force-adjustable hydraulic shock absorbers 1 connected to both sides of the pipe line 2 are different, these pressures are not
Therefore, the free piston 41 and the magnetic fluid 42 can be reliably returned to the neutral position by the spring force of the spring 45.

As shown in FIG. 6, a magnetic field generating means is replaced by a coil instead of a permanent magnet as shown in FIG.
By providing 48 and energizing the coil 48 from the power supply 49,
A magnetic field may be generated. in this case,
Furthermore, a current control device 50 for controlling the output current of the power supply 49 is provided, and based on parameters representing the running state of the vehicle, such as the vehicle speed and the steering angle, the current supplied to the coil 48 is adjusted to provide the magnetic fluid 42 with By adjusting the strength of the applied magnetic field, the damping force of the shock absorber 1 can be optimally controlled according to the running state.

In addition, the high-frequency filter shown in FIG. 7 can be used. In the high-frequency filter 51 shown in FIG. 7, a free piston 53 is slidably fitted in a cylinder portion 52 provided in the middle of the pipeline 2, and two chambers 52L and 52R defined by the free piston 53. Is pipeline 2
Are respectively connected to the shock absorbers 1 on the left and right sides of the vehicle body. The free piston 53 is provided with an oil passage 54 for communicating between the chambers 52L and 52R, and the oil passage 54 is provided with an orifice 55 (throttle passage). Springs 56 and 57 are provided between both ends of the free piston 53 and both ends of the cylinder portion 52, respectively.
(Holding means) is interposed, and the free piston 53 is held at a neutral position with a predetermined set load by the spring force of these springs 56 and 57. On the inner wall of the cylinder portion 52, a plurality of axial grooves 58 and 59 are formed on both sides of the neutral position of the free piston 53, respectively, and when the free piston 53 moves left and right from the neutral position, The chambers 52L and 52R communicate with each other via the grooves 58 and 59.

The operation of the high-frequency filter 51 thus configured will be described below. When the piston rods 7 of the shock absorbers 1 on the left and right sides of the vehicle body stroke in opposite phases, the spool 25
As a result, the flow of the oil liquid occurs in the pipeline 2. Due to the flow of the oil liquid in the oil passage 54 of the free piston 53 due to this,
The damping force is applied by the orifice 55 to suppress the movement of the spool 25. At this time, the free piston 53 is
Due to the flow of the oil liquid, the springs 56 and 57 move against the spring force.

When the stroke of the piston rod 7 is high-frequency vibration having a relatively small amplitude, the free piston 53
Has a small moving amount and strokes near the neutral position.
Therefore, the damping force of the orifice 55 causes the spool 25
Is suppressed, and the damping force of the shock absorber 1 is maintained in a low state.

When the stroke of the piston rod 7 is a low-frequency vibration having a relatively large amplitude, the free piston 53
Has a large moving amount and strokes beyond the vicinity of the neutral position. When the free piston 53 moves beyond the vicinity of the neutral position, the grooves 52 or 59 allow communication between the chambers 52L and 52R on both sides of the free piston 53 to bypass the orifice 55 of the oil passage 54. As a result, the amount of movement of the spool 25 increases, and the damping force of the shock absorber 1 increases.

As described above, similarly to the above-described high-frequency filter using the magnetic fluid, the damping force of the shock absorber 1 is appropriately increased by allowing the movement of the spool 25 with respect to a change in the posture of the vehicle body during turning. Thereby, the rolling stability of the vehicle body can be improved by suppressing the rolling of the vehicle body.
By keeping the damping force of the vehicle low, it is possible to obtain a good ride quality. At this time, even if the pressures in the respective reservoirs 5 of the damping force-adjustable hydraulic shock absorbers 1 connected to both sides of the pipe line 2 are different, these pressures are balanced through the oil passage 54, so that the spring 56 , 57, the free piston 53 can be reliably returned to the neutral position.

In the embodiment shown in FIGS. 1 to 7, the damping force is adjusted by a pressure control valve as shown in FIG. 8 instead of the shock absorber 1 which adjusts the damping force by a spool valve (flow control valve). A damping force-adjustable hydraulic shock absorber 60 (hereinafter, shock absorber 60) can also be used. Note that, in FIG. 8, the same reference numerals are given to the same parts in the shock absorber 1 shown in FIG.

As shown in FIG. 8, in the shock absorber 60, a valve body for controlling the pressure between the ports 22 and 23 and between the ports 31 and 32 of the extension-side and contraction-side damping force generating mechanisms is provided in the piston bolt 15. 61 is slidably fitted. The valve element 61 is urged by the pressure difference between the cylinder lower chambers 3b of the left and right shock absorbers 60, and moves downward in the drawing to thereby extend the port on the extension side.
By closing the flow path between 22 and 23 and moving upward in the drawing, the flow path between the contraction side ports 31 and 32 is closed, and in the neutral position, the flow path between the extension side ports 22 and 23 and the contraction Side port
Both channels between 31 and 32 are opened.

As in the case shown in FIG. 2, by changing the flow passage area between the ports 22 and 23 and between the ports 31 and 32 by the valve body 61, the damping force on the extension side and the contraction side is adjusted. Thus, the pressure in the back pressure chambers 20, 29 can be changed, and the damping force characteristics can be adjusted by changing the valve opening pressures of the disc valves 17, 26. Function and effect can be achieved.

In the embodiment shown in FIGS. 1 to 8, the damping force-adjustable hydraulic shock absorber is disposed on the left and right sides of the vehicle.
Although a device that suppresses rolling of the vehicle has been described, in addition, by arranging a damping force-adjustable hydraulic shock absorber on the front and rear sides of the vehicle, pitching of a vehicle (including a motorcycle) (for example, turning forward or braking during braking). It is also possible to suppress a fall after acceleration).

[0037]

As described above in detail, according to the suspension device of the first aspect, the front-rear or left-right damping force-adjustable hydraulic shock absorbers are connected to each other by a pipe, and a resistance means is provided in the pipe. Accordingly, with respect to a change in the posture of the vehicle body during a turn or the like, the change in the posture of the vehicle body is suppressed by appropriately increasing the damping force of the damping force-adjustable shock absorber in accordance with the movement of the oil liquid in the pipeline. To improve steering stability,
In addition, with respect to unsprung vibration, the damping force of the damping force adjustable shock absorber is maintained low by providing resistance to the movement of the oil liquid in the pipeline by the resistance means, and a good ride comfort is provided. Obtainable. According to the suspension device of claim 2, by providing the magnetic fluid and the magnetic field generating means as the resistance means, when the movement of the oil liquid in the pipeline is small, the magnetic fluid generates the magnetic field of the magnetic field generating means. Since the magnetic fluid moves within the range, the viscosity of the magnetic fluid increases, and a large resistance can be given to the movement of the oil liquid in the pipeline. Since the magnetic fluid moves beyond the range of the magnetic field of the magnetic field generating means, the viscosity of the magnetic fluid decreases, and the resistance to the movement of the oil liquid in the pipeline can be reduced. Further, according to the suspension device of claim 3, since the free piston having the throttle passage is fitted into the cylinder having the groove as the resistance means, the movement of the oil liquid in the pipeline is reduced. When it is small, the free piston moves near the neutral position together with the oil liquid in the pipeline, so that a large resistance can be given to the movement of the oil liquid by the throttle passage. On the other hand, when the movement of the oil liquid in the pipeline is large, the free piston moves beyond the vicinity of the neutral position together with the oil liquid in the pipeline, so that the two chambers in the cylinder unit communicate with each other through the groove, thereby restricting the throttle. Since the passage is bypassed, resistance to the movement of the oil liquid can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a suspension device according to an embodiment of the present invention.

FIG. 2 is an enlarged view showing a main part of a damping force adjusting type hydraulic shock absorber of the apparatus of FIG. 1;

FIG. 3 is an enlarged schematic view showing a high-frequency filter of the apparatus of FIG. 1;

FIG. 4 is an enlarged schematic view showing a high-frequency filter according to another embodiment of the present invention.

FIG. 5 is an enlarged schematic view showing a high-frequency filter according to still another embodiment of the present invention.

FIG. 6 is an enlarged schematic view showing a high-frequency filter according to still another embodiment of the present invention.

FIG. 7 is an enlarged schematic view showing a high-frequency filter according to still another embodiment of the present invention.

FIG. 8 is a longitudinal sectional view of a main part of a damping force adjusting type hydraulic shock absorber that can be used in the apparatus of FIG. 1;

[Explanation of symbols]

 1 Damping force adjustable hydraulic shock absorber 2 Pipe line 3 Cylinder 6 Piston 11 Extension side oil path 12 Retraction side path 7 Piston rod 13 Extension side damping force generation mechanism 14 Retraction side damping force generation mechanism 39,51 High frequency filter (resistance means) 41 Free piston 42 Magnetic fluid 43 Permanent magnet (magnetic field generating means) 48 Coil (magnetic field generating means) 52 Cylinder section 53 Free piston 55 Orifice (throttle passage) 58, 59 Groove section

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16F 9/53 F16F 9/32 P Z

Claims (3)

[Claims] 1. A cylinder filled with an oil liquid, a piston slidably fitted in the cylinder, and a piston having one end connected to the piston and the other end extending outside the cylinder. A rod, an oil passage through which the oil flows by sliding of the piston, and a damping force generating mechanism that controls the flow of the oil in the oil passage to generate a damping force and adjusts the damping force. The damping force-adjustable hydraulic shock absorber provided is mounted on the front and rear or left and right wheels of the vehicle, respectively, and the oil chambers in the front and rear or left and right damping force-adjustable hydraulic shock absorbers are communicated with each other by a pipeline, and the oil chamber When the damping force generating mechanism is switched according to the movement of the oil liquid in the pipeline caused by the pressure difference between the piston rods, the strokes of the piston rods of the front and rear or left and right damping force adjusting hydraulic shock absorbers are in phase. , Reduce the damping force And a resistance means for increasing the damping force in the opposite phase and providing resistance only to movement of the oil liquid within a predetermined range in the pipeline. 2. The resistance means includes a magnetic fluid contained between a pair of free pistons slidably fitted in the conduit, and a magnetic field generating means for applying a magnetic field to the magnetic fluid. 2. The suspension device according to claim 1, wherein the suspension device is provided. 3. The cylinder according to claim 1, wherein the resistance means includes: a cylinder formed in the pipe; a free piston slidably fitted in the cylinder to define the cylinder in two chambers; A throttle passage that communicates the two chambers with each other, and an axial groove disposed on both sides of the free piston at a neutral position of the inner wall of the cylinder portion. The suspension device as described.