JP3346221B2 - shock absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber used for a suspension of a vehicle, for example.

[0002]

2. Description of the Related Art Conventionally, a suspension for a vehicle having a shock absorber and a suspension spring, in which the damping force of the shock absorber can be changed in accordance with the running state of the vehicle (so-called active suspension). Has been put to practical use. In this type of suspension, there is also provided one that performs so-called skyhook control.

[0003] The skyhook control is a control for suppressing the sprung portion (the vehicle body mass side) supported by the suspension spring from swinging up and down. That is, when the vehicle body is displaced upward, the shock absorber is prevented from operating toward the extension side, and when the vehicle body is displaced downward, the shock absorber is prevented from operating toward the compression side.

As a conventional suspension of this kind,
As shown in FIG. 29, a suspension spring 2 supporting a body mass 1
A shock absorber 3 for generating a damping force with respect to a vertical vibration, a sensor 4 for detecting a vertical acceleration of the vehicle body mass 1, an arithmetic processing circuit 5 including a microprocessor or the like, and a drive circuit 6 And so on. The shock absorber 3 includes an electric actuator 7 such as an electromagnetic solenoid or a stepping motor for switching the damping force. A wheel 8 is provided below the suspension spring 2 (under the spring). When the vehicle body mass 1 moves upward or downward, the output signal of the sensor 4 is electrically processed by the arithmetic processing circuit 5, and the electric actuator 7 is operated via the drive circuit 6.

[0005]

The above-mentioned conventional electronically controlled suspension capable of skyhook control has a large number of parts, a complicated structure, and a high cost. In addition, it takes time to process the signal from the sensor 4 in the arithmetic processing circuit 5, and it takes time for the electric actuator 7 to move to the predetermined position. For this reason, there was a disadvantage that the response to a change in the road surface was poor.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shock absorber which has a simple structure, can provide a skyhook effect at low cost, and has excellent responsiveness to a change in road surface.

[0007]

According to a first aspect of the present invention, there is provided a shock absorber according to the present invention, which has a biasing means for supporting a movable mass in a floating state at a predetermined neutral position. A first spring disposed below the movable mass and pushing up the movable mass to the neutral position; and a biasing unit disposed above the movable mass and moving the movable mass to the neutral position. And a second spring that pushes down to the side. Furthermore, the shock absorber of the present invention
It has an interlocking member that interlocks with the vertical movement of the movable mass.
The damping force according to the vertical position of the movable mass.
It is provided with a damping force generator for variably controlling. Vibration feeling
The sensing mechanism is located inside the piston rod or the piston.
The movable mat is formed inside a casing provided on the rod.
And an outer chamber of the movable mass.
The flow control unit, the internal chamber and the flow control unit
First small liquid chamber partitioned and formed on the first spring side
And the second chamber partitioned by the internal chamber and the flow control unit.
A second liquid chamber formed on the spring side of the second liquid chamber.
In the shock absorber of the present invention, when the vehicle body mass moves in the vertical direction, the movable mass of the vibration detection mechanism moves relative to the vehicle body mass. That is, if the natural frequency of the sprung system including the vehicle body mass and the suspension spring and the natural frequency of the mass spring system of the vibration detection mechanism are brought close to some extent,
When the vehicle body mass descends, the movable mass relatively rises, and accordingly, the interlocking member of the damping force generating section operates to increase the damping force on the compression side of the shock absorber. Conversely, when the vehicle body mass rises, the movable mass relatively lowers, and accordingly, the interlocking member of the damping force generating portion operates to increase the extension side damping force of the shock absorber.

As will be described later, the resonance frequency on the spring is ω
s, when the resonance frequency of the mass spring system of the vibration detecting mechanism is ωd, the resonance frequency ratio (ωd / ωs) is suitably 2.5 or less.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a suspension 10 used for a vehicle such as an automobile includes a suspension spring 11 and a shock absorber 12. The suspension spring 11 is provided between the upper seat 13 and the lower seat 14 in a compressed state.

One example of the shock absorber 12 is the outer cylinder 2
The cylinder 22 includes a double-walled cylinder 22 having an inner cylinder 21 and a hollow piston rod 23 inserted into the cylinder 22. The piston rod 23 is supported by a bearing 24 so as to be movable in the axial direction of the cylinder 22. A working fluid such as oil is contained in the cylinder 22. A base valve part 25 is provided near the bottom of the cylinder 22.
Is provided. An air chamber 26 is provided at an upper portion between the outer cylinder 20 and the inner cylinder 21 that constitute the cylinder 22.

In this specification, the movement of the piston rod 23 in the direction in which it protrudes from the cylinder 22 is referred to as "moving to the extension side".
Moving in the direction of being pushed into 2 is referred to as "moving to the pressure side".

The upper end 30 of the piston rod 23 is connected to a vehicle body-side member 32 via a mount insulator 31. Bump rubber 3 on the lower surface side of upper sheet 13
3 are provided. A knuckle mounting bracket 34 is provided at the lower end of the cylinder 22, and wheels 35 (shown in FIG. 2 and the like) are supported via knuckles (not shown) provided on the bracket 34.

A cylindrical shaft portion 41 having a through hole 40 extending in the axial direction is formed below the piston rod 23. The shaft 41 is located inside the cylinder 22. The shaft portion 41 is provided with a damping force generating portion 43 having a piston portion 42. The piston part 42 partitions the inside of the cylinder 22 into an upper first liquid chamber 45 and a lower second liquid chamber 46.

As shown in an enlarged view of the damping force generating portion 43 in FIG. 5 and the like, the piston portion 42 is provided with a piston valve 50 such as a disc valve and a flow path 51 which open when the piston rod 23 moves to the extension side. , A piston valve 52 such as a disk valve that opens when the piston rod 23 moves to the pressure side, and a flow path 53 are provided.

In the hollow shaft portion 41, a first orifice 55, a second orifice 56, and a third
An orifice 57 is formed. A sub-piston 60 is provided above the piston part 42. The internal liquid chambers 61 and 62 of the sub piston 60 are respectively provided with the first orifice 5.
5 and the second orifice 56.

The first liquid chamber 45 is provided above the sub piston 60.
A one-way valve 63 is provided to allow the working fluid inside the sub-piston 60 to flow into the internal liquid chamber 61. A one-way valve 64 that allows the hydraulic fluid in the internal fluid chamber 62 to flow out is provided below the sub-piston 60. Third orifice 57 located below sub-piston 60
Communicates with the first liquid chamber 45 via a horizontal hole 66 formed in the spacer member 65.

A cylindrical spool member 70 functioning as an interlocking member is accommodated in the through hole 40 of the shaft portion 41.
This spool member 70 is movable in the axial direction of the shaft 41. A first communication hole 71, a second communication hole 72, and a third communication hole 73 are formed in the spool member 70 in order from the top. The lower end of the spool member 70 is open, so that the working fluid can freely enter and exit the inside of the spool member 70.

As shown in FIG. 5, when the spool member 70 is at a neutral position in the vertical direction with respect to the shaft portion 41, the first orifice 55 communicates with the first communication hole 71, and the second orifice 56 communicates with the second communication hole. The third orifice 57 communicates with the third flow hole 73 by communicating with the hole 72.

When the spool member 70 moves to a predetermined position (up end) with respect to the shaft portion 41 as shown in FIG. 6, the first orifice 55 and the first flow hole 71 communicate with each other, and the second orifice 55 The communication between 56 and the second communication hole 72 is cut off, and the communication between the third orifice 57 and the third communication hole 73 is cut off.

As shown in FIG. 7, when the spool member 70 moves to a predetermined position (downward end) with respect to the shaft portion 41, the second orifice 56 and the second flow hole 72 communicate with each other and the first orifice The communication between the first orifice 55 and the first communication hole 71 is cut off, and the communication between the third orifice 57 and the third communication hole 73 is cut off.

A movable mass 80 having a predetermined mass is provided above the spool member 70. A material having a large specific gravity, such as lead, is suitable for the movable mass 80.
Are housed so as to be movable in the axial direction. Movable mass 80
Is connected to the upper end of the spool member 70. Therefore, the movable mass 80 and the spool member 70 can move in the vertical direction integrally with each other.

On the outer periphery of the movable mass 80, a ring-shaped flow control unit 82 functioning as a damping means is provided.
Small liquid chambers 83 and 84 are defined on the upper side and the lower side of the flow control unit 82, respectively. The small liquid chambers 83 and 84 are filled with the same working liquid as oil contained in the liquid chambers 45 and 46.

The small liquid chambers 83 and 84 communicate with each other via a flow control unit 82. When the movable mass 80 moves in the vertical direction, the working fluid flows through the flow control unit 82 so that the movable mass 80 reciprocating motion can be attenuated.

The movable mass 80 is prevented from moving above the above-mentioned rising end (the position shown in FIG. 6) by a stopper member 87 provided on the upper end side of the piston rod 23. The movable mass 80 is prevented from moving below the lower end (the position shown in FIG. 7) by a stopper 88 provided at the lower end of the movable mass 80.

Below the movable mass 80, there is provided a first spring 91 functioning as an urging means for pushing up the movable mass 80 toward the neutral position shown in FIG. Above the movable mass 80, there is provided a second spring 92 functioning as a biasing means for pushing the movable mass 80 back toward the neutral position. One example of these springs 91 and 92 is a compression coil spring, and both spring constants are set so that the movable mass 80 can be supported at the neutral position in a floating state.

That is, the lower first spring 91 is provided with a second spring 92 to overcome the weight of the movable mass 80 and generate a repulsive load sufficient to push the movable mass 80 to the neutral position. Also, those with a large spring constant are used. On the other hand, the second spring 92 has the movable mass 80
When the first spring 91 rises beyond the neutral position, a repulsive load sufficient to push the movable mass 80 back to the neutral position may be generated, so that a spring constant smaller than that of the first spring 91 is used.

FIG. 8 schematically shows a vibration system of the suspension 10. In this figure, a mass spring system including a movable mass 80 and springs 91 and 92, a flow control unit 82 for attenuating the vibration of the movable mass 80, and the like include a seismic system (seis) that functions as a vibration sensing mechanism 95.
mic system). On the other hand, the body mass 97 including the weight of the body 96, the suspension spring 11, the damping force generation unit 43 of the shock absorber 12, etc.
8.

Next, the shock absorber 12 having the above-described structure will be described.
The operation of the suspension 10 having the above will be described.
When the vehicle is running, as shown in FIG. 2, when the vehicle body 96 is substantially stationary in the vertical direction and the unsprung state, that is, the wheel 35 side vibrates in the vertical direction due to unevenness of the road surface, the piston rod 23 is substantially stationary. Therefore, the movable mass 80 in the piston rod 23 is maintained at a substantially neutral position. For this reason, the spool member 70 is substantially at the neutral position as shown in FIG. In this case, the first orifice 5
5, the second orifice 56 and the third orifice 57 are formed by the first through hole 71, the second through hole 72 and the third through hole 73, respectively.
Communicate with

As described above, the movable mass 80 and the spool member 7
When the cylinder 22 moves downward (extending side) with respect to the piston rod 23 when 0 is at the neutral position, the hydraulic fluid flows as shown by the solid arrow in FIG. That is, part of the working fluid in the first fluid chamber 45 is
After flowing into the internal liquid chamber 61 through the one-way valve 63,
It flows into the inside of the spool member 70 via the first orifice 55 and flows out to the second liquid chamber 46 side. A part of the working fluid in the first liquid chamber 45 flows out to the second liquid chamber 46 via the third orifice 57.

When the movable mass 80 and the spool member 70 are at the neutral position as described above, the piston rod 23
When the cylinder 22 moves in the upward direction (pressure side), the hydraulic fluid flows as indicated by the broken arrow in FIG.
That is, a part of the hydraulic fluid in the second liquid chamber 46 passes through the inside of the spool member 70 and flows out to the first liquid chamber 45 through the third orifice 57. A part of the hydraulic fluid flowing into the inside of the spool member 70 flows into the internal fluid chamber 62 of the sub-piston 60 through the second orifice 56, and then passes through the one-way valve 64 to the first fluid chamber 45 side. leak. In this way, the working fluid flows through the damping force generating section 43 in accordance with the moving direction of the piston rod 23, so that the reciprocating motion of the piston rod 23 with respect to the cylinder 22 is attenuated.

As shown in FIG. 3, when the sprung mass (body 96) moves downward, the movable mass 80 relatively rises as shown in FIG. 6, so that the spool member 70 moves to the rising end position. In this case, the communication between the second orifice 56 and the second communication hole 72 is cut off, and the communication between the third orifice 57 and the third communication hole 73 is cut off.

Therefore, when the cylinder 22 moves relatively to the extension side in this state, the hydraulic fluid flows as shown by the solid arrow in FIG. That is, part of the working fluid in the first fluid chamber 45 is
One-way valve 6 of sub-piston 60 having relatively small flow resistance
3, and flows into the inside of the spool member 70 through the first orifice 55. It flows into the second liquid chamber 46. The first liquid chamber 4
A part of the working fluid in 5 flows through the piston valve 50 to the second fluid chamber 46. Therefore, it becomes a relatively soft damping force,
The shock absorber 12 is allowed to move to the extension side.

On the other hand, when the cylinder 22 relatively moves to the pressure side, the hydraulic fluid flows as shown by the dashed arrow in FIG. That is, the hydraulic fluid in the second liquid chamber 46 flows into the first liquid chamber 45 through the piston valve 52 having a relatively large flow resistance. In this case, a relatively hard damping force is provided, and the shock absorber 12 is suppressed from moving to the compression side.

On the other hand, when the vehicle body 96 moves upward as shown in FIG. 4, since the movable mass 80 relatively descends as shown in FIG. 7, the spool member 70 moves to the lower end position. In this case, the first orifice 55 and the first flow hole 7
Communication with the first orifice 57 and the third orifice 57
The communication with the circulation hole 73 is also cut off.

Therefore, when the cylinder 22 moves relatively to the extension side in this state, the hydraulic fluid flows as shown by the solid arrow in FIG. That is, since a part of the hydraulic fluid in the first fluid chamber 45 flows into the second fluid chamber 46 only through the piston valve 50 having a relatively large flow resistance, the damping force becomes hard, and the shock absorber 12 moves toward the extension side. Movement is suppressed.

On the other hand, when the cylinder 22 relatively moves to the pressure side, the hydraulic fluid flows as shown by the dashed arrow in FIG. That is, the hydraulic fluid in the second liquid chamber 46 flows into the first liquid chamber 45 through the piston valve 52 having a relatively small flow resistance. A part of the working fluid in the second fluid chamber 46 passes through the inside of the spool member 70 and flows into the first fluid chamber 45 through the second orifice 56 and the one-way valve 64. For this reason, the damping force is relatively soft, and the shock absorber 12 is allowed to move to the extension side.

As described above, when the sprung mass (body mass 97) descends and rises, the damping force on the extension side and that on the compression side are differentiated, so that the damping force characteristic as shown in FIG. And a so-called skyhook effect can be obtained.

FIG. 10 shows a characteristic C1 of the shock absorber 12 of the above embodiment, a characteristic C2 of a general shock absorber having a soft damping force, and a characteristic C2 of a general shock absorber having a medium damping force. This is a comparison with the characteristic C3. The frequency ratio on the horizontal axis represents (the natural frequency of the vehicle mass / the road surface input frequency). The characteristic C1 of the shock absorber 12 of this embodiment was able to reduce the vibration transmissibility in a wide range of frequency ratios as compared with the characteristics C2 and C3 of a general shock absorber.

Here, the resonance frequency of the sprung system 98 (shown in FIG. 8) comprising the suspension spring 11 and the shock absorber 12 is represented by ωs, and the resonance of the vibration sensing mechanism 95 comprising the movable mass 80 and the springs 91 and 92. When the frequency is ωd, by setting the resonance frequency ratio (ωd / ωs) to 2.5 or less, as shown in FIG. 11 and FIG. The displacement could be kept to a sufficiently low level. However, if the resonance frequency ratio (ωd / ωs) is less than 0.5, a practical vibration sensing mechanism 95 cannot be established. Therefore, in the present invention, the resonance frequency ratio (ωd / ωs) is set to 0.5. , The weight of the movable mass 80 and the spring 9
A spring constant of 1,92 is set. The skyhook effect can be obtained in a wide vibration frequency range by increasing the damping ratio of the vibration sensing mechanism 95.
The Cd value in FIGS. 11 and 12 is the viscous damping coefficient of the vibration sensing mechanism 95.

Next, a second embodiment of the present invention will be described.
This will be described with reference to FIGS. The shock absorber 1 of the suspension 10A of the second embodiment
2A has the same configuration as that of the shock absorber 12 of the first embodiment except for the damping force generating section 43A.

The shock absorber 12 of the second embodiment
In A, the configuration of the damping force generator 43A is more simplified than that of the damping force generator 43 of the first embodiment.
That is, as shown in an enlarged manner in FIG. 14, the damping force generating section 43A mainly includes a piston section 110 and a cylindrical slide member 111 functioning as an interlocking member. The sliding member 111 is a piston rod 23
And is movable in the axial direction of the piston rod 23. The upper end of the slide member 111 is connected to the lower end of the movable mass 80.

The intermediate portion of the slide member 111 in the axial direction is formed by reducing the outer diameter over a predetermined length,
A flow portion 112 extending in the axial direction of the slide member 111 is formed. In the lower part of the piston rod 23, the first communication hole 11 that can communicate with the vicinity of the upper end of the flow portion 112 is provided.
5 and a second communication hole 116 that can communicate with the vicinity of the lower end of the flow portion 112. Piston rod 23
The lower end side of the through hole 40 is sealed by a stopper 117.

The piston section 110 is provided with the same piston valves 50 and 52 and flow paths 51 and 53 as in the first embodiment. The piston portion 110 has a second
A bypass passage 120 communicating with the communication hole 116 is formed.

As shown in FIG. 14, the slide member 111
Is located at a neutral position in the vertical direction with respect to the piston rod 23, the first communication hole 115 communicates with the upper end side of the flow portion 112 of the slide member 111, and the second communication hole 116 communicates with the lower end of the flow portion 112. Communicate with the side.

Further, as shown in FIG.
When the first communication hole 1 moves to a predetermined position (up end) with respect to the piston rod 23, the second communication hole 116 is connected to the slide member 111 while the first communication hole 115 is in communication with the flow portion 112.
Is to be closed by.

Then, as shown in FIG.
When the first communication hole 11 moves to a predetermined position (downward end) with respect to the piston rod 23, the first communication hole 115
11, and the second communication hole 116 and the flow portion 112 communicate with each other.

Next, the operation of the shock absorber 12A according to the second embodiment will be described. As shown in FIG.
When the vehicle body 96 is almost stationary in the vertical direction and the spring is unsprung due to the unevenness of the road surface, that is, when the wheels 35 vibrate in the vertical direction, the piston rod 23 is almost stationary and the movable mass in the piston rod 23 is 80 is maintained in a substantially neutral position. Therefore, the slide member 111 is almost at the neutral position as shown in FIG. In this case, the first communication hole 115 communicates with the upper end side of the flow portion 112 of the slide member 111 and the second communication hole 11
6 communicates with the lower end of the circulation section 112.

As described above, the movable mass 80 and the slide member 1
When the cylinder 22 moves downward (extended side) with respect to the piston rod 23 when the position 11 is in the neutral position, the hydraulic fluid flows as indicated by the solid arrow in FIG. That is, a part of the working fluid in the first fluid chamber 45 is
15, flows into the second liquid chamber 46 through the circulation part 112 and the bypass channel 120. A part of the working fluid in the first fluid chamber 45 flows into the second fluid chamber 46 through the piston valve 50.

When the movable mass 80 and the slide member 111 are in the neutral position as described above, the piston rod 23
When the cylinder 22 moves in the upward direction (pressure side), the hydraulic fluid flows as shown by the broken arrow in FIG. That is, a part of the working fluid in the second fluid chamber 46 passes through the bypass passage 120,
2 and further through the first communication hole 115 to the first liquid chamber 4.
Flow into 5. A part of the working fluid in the second fluid chamber 46 flows into the first fluid chamber 45 through the piston valve 52. Thus, the piston rod 2 with respect to the cylinder 22
3 reciprocating motion is damped.

As shown in FIG. 3, when the vehicle body 96 moves downward, the movable mass 80 relatively rises as shown in FIG. 15, so that the slide member 111 moves to the rising end position. In this case, the second communication hole 116 is closed by the slide member 111.

Accordingly, when the cylinder 22 relatively moves to the extension side in this state, the hydraulic fluid can flow as shown by the solid arrow in FIG. That is, a part of the working fluid in the first fluid chamber 45 passes through the piston valve 50 and passes through the second fluid chamber 4.
6 can flow.

When the pressure of the first liquid chamber 45 increases, as shown in an enlarged view in FIG.
The slide member 111 moves in the downward direction, that is, in the direction in which the flow path expands, due to the fluid force of the working fluid ejected from the pressure receiving portion 121 of the circulation portion 112 of FIG. Here, the fluid force will be described. At the throttle portion between the pressure receiving portion 121 of the slide member 111 and the piston rod 23, the slide member fluid force (axial force of the slide member 111) is generated by the jet of the working fluid. When A is a high-pressure section and B is a low-pressure section, the fluid force f can be represented by f = ρQ (V2−V1) when expressed by an equation. Here, V1: the flow velocity of the high-pressure section A V2: the flow velocity of the low-pressure section B ρ: the density of the fluid (working fluid) Q: the flow rate When the high-pressure section A and the low-pressure section B are reduction tubes, a fluid force acts in the flow direction The desired lower damping force can be obtained by the action of opening the throttle portion by the fluid force. In this way, the hydraulic fluid in the circulation part 112 flows out to the second liquid chamber 46 side via the second communication hole 116 and the bypass channel 120. Therefore, the damping force is relatively soft, and the shock absorber 12
A is allowed to move to the extension side.

When the cylinder 22 relatively moves to the pressure side, the second communication hole 116 is kept closed by the slide member 111 as shown in FIG. In this case, the fluid force due to the jet of the working fluid acts in a direction in which the throttle portion between the pressure receiving portion 121 and the piston rod 23 is closed, so that it is convenient to obtain a desired high damping force. In this case, the hydraulic fluid is supplied to the piston valve 52 as shown by the dashed arrow in FIG.
And flows into the first liquid chamber 45. For this reason, a hard damping force is provided, and the shock absorber 12A is suppressed from moving to the compression side.

On the other hand, when the vehicle body 96 moves upward as shown in FIG. 4, since the movable mass 80 relatively descends as shown in FIG. 17, the slide member 111 moves to the descending end position. In this case, the first communication hole 115 is closed by the slide member 111.

Accordingly, when the cylinder 22 relatively moves to the extension side in this state, the hydraulic fluid flows into the second liquid chamber 46 only through the piston valve 50 having a relatively large flow resistance as shown by a solid line arrow in FIG. I do. Therefore, a hard damping force is generated, and the piston rod 23 is suppressed from moving toward the extension side.

On the other hand, when the cylinder 22 relatively moves to the pressure side, the hydraulic fluid can flow as shown by the dashed arrow in FIG. That is, a part of the hydraulic fluid in the second fluid chamber 46 passes through the piston valve 52 to the first fluid chamber 4.
5 can flow. When the pressure of the second liquid chamber 46 increases, as shown in FIG.
The slide member 111 moves upward, that is, in the direction in which the flow path expands, due to the fluid force of the working fluid ejected from the pressure receiving portion 122 of the twelve, that is, the working fluid reaction force. Therefore, the distribution unit 112
The hydraulic fluid in the first liquid chamber 45 passes through the first communication hole 115.
Spill to the side. Therefore, the damping force is relatively soft, and the shock absorber 12A is allowed to move to the compression side.

As described above, when the sprung mass (the body mass 97) descends and ascends, the damping force on the extension side and the damping force on the compression side are made different from each other, as shown in FIG. At the time of descent and at the time of ascent, the damping force can be shifted from the characteristic indicated by the two-dot chain line to the apparent characteristic indicated by the solid line, and the skyhook effect can be obtained.

Next, a third embodiment of the present invention will be described.
This will be described with reference to FIGS. In the shock absorber 12B of this embodiment, the same members as those of the shock absorber 12A of the second embodiment are denoted by the same reference numerals, description thereof will be omitted, and different points will be described below.

The shock absorber 12B of the third embodiment has regulating members 130 and 131 for holding the springs 91 and 92 of the vibration sensing mechanism 95 in a compressed state. These regulating members 130, 131
The length is set to a predetermined length in the axial direction of the piston rod 23 so that the first and the second 92 can be held with a predetermined initial deflection.

That is, the upper end of the lower spring 91 faces the lower part of the movable mass 80 via the spring seat 132,
The upward movement of the spring seat 132 is regulated by the locking portion 130a of the regulating member 130. The lower end of the upper spring 92 faces the upper part of the movable mass 80 via the spring seat 133, and the downward movement of the spring seat 133 is regulated by the locking portion 131 a of the regulating member 131.

Accordingly, as shown in FIG. 23, when the movable mass 80 is at the neutral position, the centering force due to the initial deflection of the springs 91 and 92 can be exerted. By doing so, the movable mass 80 and the slide member 111 can be accurately held at the predetermined neutral position without being affected by the variation of the repulsive load or the free length of the springs 91 and 92. In addition, when the movable mass 80 is at the neutral position, a dead zone that is less susceptible to vibration to some extent can be set.

The shock absorber 12B of the third embodiment is different from the shock absorber 12A of the second embodiment.
Similarly, as shown in FIG. 20, when the slide member 111 is at the neutral position in the vertical direction with respect to the piston rod 23, the first communication hole 115 communicates with the upper end side of the flow portion 112 of the slide member 111. , The second communication hole 11
6 communicates with the lower end of the circulation section 112. When the cylinder 22 relatively moves to the extension side, the hydraulic fluid flows as indicated by a solid arrow, and when the cylinder 22 relatively moves to the pressure side, the hydraulic fluid flows as indicated by a broken arrow.

Then, when the vehicle body 96 is lowered, as shown in FIG.
As shown in FIG.
, The second communication hole 116 is closed by the slide member 111. Therefore, when the cylinder 22 relatively moves to the extension side in this state,
When the hydraulic fluid flows as indicated by the solid line arrow in FIG. 21 and the pressure in the first fluid chamber 45 increases, the slide member 111 slightly moves downward due to the pressure of the hydraulic fluid in the flow portion 112, so that the hydraulic fluid flows. The second through the bypass channel 120
It can flow out to the liquid chamber 46 side. Therefore, the damping force is relatively soft, and the shock absorber 12B is allowed to move to the extension side. When the cylinder 22 moves relatively to the pressure side, the hydraulic fluid flows as indicated by the dashed arrow.

When the vehicle body 96 is lifted, the
As shown in FIG.
The first communication hole 115 is closed by the slide member 111 by moving to the lower end. Therefore, when the cylinder 22 relatively moves to the extension side in this state,
The hydraulic fluid flows as indicated by the solid arrow. When the cylinder 22 moves relatively to the pressure side, the hydraulic fluid flows as indicated by a broken line arrow in FIG. 22, and when the pressure of the second fluid chamber 46 increases, the slide member 111 slightly moves upward due to the reaction force of the hydraulic fluid. Thereby, the working fluid in the circulation part 112 can flow out to the first liquid chamber 45 side. Therefore, the damping force is relatively soft, and the shock absorber 12B is allowed to move to the compression side. For this reason, the shock absorber 12B of the third embodiment can also obtain the same skyhook effect as the shock absorber 12A of the second embodiment.

Next, a fourth embodiment of the present invention will be described.
This will be described with reference to FIGS. The shock absorber 12C of the suspension 10C according to this embodiment includes:
The position where the vibration sensing mechanism 95 is provided is different from the shock absorber 12A of the second embodiment. Other configurations and operations are the same as those of the second embodiment, and therefore, members common to both are denoted by common reference numerals, and description thereof is omitted.

The shock absorber 12C of this embodiment
Is provided with a vibration sensing mechanism 95 at the upper end of the piston rod 23. As shown in FIG. 25 or FIG. 26, the vibration sensing mechanism 95 includes a casing 153 including a lower case 150, an upper case 151, an inner case 152, and the like, and a movable mass 80 housed inside the casing 153. It is composed of springs 91 and 92 for urging the movable mass 80 in a floating state at the neutral position.

The first small liquid chamber 155 is defined between the upper case 151 and the movable mass 80, and the inner case 152
A second small liquid chamber 156 is defined between the second liquid chamber 156 and the movable mass 80. Hydraulic fluid is contained in these small fluid chambers 155 and 156, and is sealed by a cap 157.

The small liquid chambers 155 and 156 communicate with each other via a flow control section 160 between the outer peripheral portion of the movable mass 80 and the inner surface of the inner case 152.
When the hydraulic fluid moves in the vertical direction, the hydraulic fluid flows through the flow control unit 160, so that the reciprocating motion of the movable mass 80 can be attenuated.

The lower case 150 is fixed to the upper end of the piston rod 23 by a nut 165. The lower case 150 and the upper case 151 are fastened to each other by a fixing member 166 such as a bolt. Movable mass 80
Is fixed to the upper end of the operating rod 170 by a nut 167. The operating rod 170 is a guide member 171
Projecting upward from the end of the.

The movable mass 80 is urged to the neutral position shown in FIG. 26 by springs 91 and 92 functioning as urging means. The lower spring 91 is held in a state where a predetermined initial deflection is given between the inner case 152 and the movable mass 80, and pushes up the movable mass 80 toward the neutral position. The upper spring 92 is held in a state where a predetermined initial deflection is given between the upper case 151 and the movable mass 80,
When the movable mass 80 rises beyond the neutral position, the movable mass 80 is pushed back to the neutral position.

The spring stopper 172 is attached to the inner case 152.
Are provided to restrict the spring seat 173 of the lower spring 91 from exceeding a predetermined height. That is, these springs 91 and 92 can exert a centering force for holding the movable mass 80 at the neutral position, as in the third embodiment.

As shown in FIG. 24, the piston rod 23
An operating rod 170 is inserted through the center of the shaft movably in the axial direction. At the lower end of the operating rod 170, the second
A damping force generator 43A having the same configuration and operation as in the embodiment is provided.

Accordingly, when the vehicle body is lowered, the movable mass 80 relatively rises as shown in FIG. 27, and the slide member 111 rises as in the second embodiment, so that in the second embodiment, The same damping force as described is obtained. When the vehicle body is raised, the movable mass 80 relatively descends as shown in FIG. 28, and the slide member 111 descends, whereby the same damping force as described in the second embodiment is obtained.

As in the shock absorber 12C of the fourth embodiment, the vibration sensing mechanism 95 is connected to the piston rod 2
In the case where the movable mass 80 is attached to the outer end of the movable mass 80, restrictions on the shape and size of the movable mass 80 are reduced, and it becomes easy to use the movable mass 80 having a desired shape or size. Further, when it is desired to change the characteristics of the vibration sensing mechanism 95 and the characteristics of the damping force generating section 43A, by removing the upper case 151,
Movable mass 80, operating rod 170 and slide member 1
It is possible to easily cope with a specification change or the like by taking out 11 or the like to the outside and replacing it with one having desired characteristics.

[0075]

According to the shock absorber of the first aspect of the present invention, the skyhook effect can be obtained by using a mechanically simple vibration sensing mechanism. According to the present invention, since the number of components is small, and the damping force is directly variably controlled by the movable mass, it is possible to provide excellent responsiveness to road surface conditions and at a low cost. Departure
Akira supports the movable mass in a floating state at a predetermined neutral position.
Movable mass in the neutral position.
When the first and second springs are initially bent.
Can demonstrate the power of tarling. Also, the movable mass is in the neutral position
At some point, a dead zone that is less susceptible to vibration
Can be set.

According to the shock absorber of the second aspect, by incorporating the vibration sensing mechanism inside the rod, it is possible to make the rod compact. In this case, since the outer shape of the shock absorber is the same as that of a normal shock absorber, the shock absorber can be directly incorporated into an existing suspension.

According to the third aspect of the present invention, since the vibration sensing mechanism is provided at the outer end of the rod, the vibration sensing mechanism can be easily changed, and a mass spring such as a movable mass or a spring can be used. Restrictions on the size and shape of the system are reduced, and it becomes easy to incorporate a desired mass spring system.

According to the shock absorbers described in claims 4 and 5, since the centering force by the spring as the urging means can be generated at the neutral position of the movable mass, the movable mass can be generated at the neutral position. It can be stably supported. Moreover, the movable mass can be accurately held at the neutral position without being affected by the variation in the spring. According to the shock absorber according to claim 6,
The configuration of the damping force generating section can be further simplified, which is more advantageous in terms of cost. According to the invention of claim 7
, The resonance frequency ratio (ωd / ωs) is reduced to 2.5 or less.
By vibrating compared to a normal shock absorber
Transmission rate and body displacement can be kept at a sufficiently low level.
it can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a suspension provided with a shock absorber according to a first embodiment of the present invention.

FIG. 2 is a side view of a part of the vehicle when a sprung state is in a neutral state.

FIG. 3 is a side view of a part of the vehicle showing a state in which a sprung portion is lowered.

FIG. 4 is a side view of a part of the vehicle showing a state in which a sprung state is raised.

FIG. 5 is a cross-sectional view when the movable mass of the shock absorber shown in FIG. 1 is at a neutral position.

FIG. 6 is a sectional view when the movable mass of the shock absorber shown in FIG. 1 is raised.

FIG. 7 is a cross-sectional view when the movable mass of the shock absorber shown in FIG. 1 is lowered.

FIG. 8 is a schematic diagram of a vibration system of the suspension shown in FIG. 1;

FIG. 9 is a diagram showing damping force characteristics of the suspension shown in FIG. 1;

FIG. 10 is a diagram showing a vibration transmissibility of the suspension shown in FIG. 1;

FIG. 11 is a diagram showing a relationship between a resonance frequency ratio and a vibration transmissibility.

FIG. 12 is a diagram showing a relationship between a resonance frequency ratio and a vehicle displacement.

FIG. 13 is a longitudinal sectional view of a suspension provided with a shock absorber according to a second embodiment of the present invention.

FIG. 14 is a sectional view when the movable mass of the shock absorber shown in FIG. 13 is at a neutral position.

FIG. 15 is a sectional view when the movable mass of the shock absorber shown in FIG. 13 is raised.

FIG. 16 is a sectional view showing a state where the slide member shown in FIG. 15 has slightly moved downward;

FIG. 17 is a sectional view of the shock absorber shown in FIG. 13 when the movable mass is lowered.

FIG. 18 is a sectional view showing a state where the slide member shown in FIG. 17 has slightly moved upward;

FIG. 19 is a view showing damping force characteristics of the shock absorber shown in FIG.

FIG. 20 is a longitudinal sectional view of a part of a shock absorber according to a third embodiment of the present invention.

FIG. 21 is a sectional view when the movable mass of the shock absorber shown in FIG. 20 is raised.

FIG. 22 is a sectional view when the movable mass of the shock absorber shown in FIG. 20 is lowered.

FIG. 23 is a view showing a relationship between displacement of a movable mass and a spring reaction force in the shock absorber shown in FIG. 20;

FIG. 24 is a longitudinal sectional view of a suspension provided with a shock absorber according to a fourth embodiment of the present invention.

FIG. 25 is an exploded cross-sectional view showing the vibration sensing mechanism of the shock absorber shown in FIG. 24;

FIG. 26 is a cross-sectional view of the shock absorber shown in FIG. 24 when the movable mass is at a neutral position.

FIG. 27 is a sectional view showing a state where the movable mass of the shock absorber shown in FIG. 24 is raised.

FIG. 28 is a sectional view showing a state where the movable mass of the shock absorber shown in FIG. 24 is lowered.

FIG. 29 is a schematic view showing a conventional suspension.

[Explanation of symbols]

 10, 10A, 10C suspension 11 suspension spring 12, 12A, 12B, 12C shock absorber 22 cylinder 23 piston rod 43, 43A damping force generator 70 spool member (interlocking member) 80 movable mass 91 , 92: spring (biasing means) 95: vibration sensing mechanism 98: sprung system 111: slide member (interlocking member)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuhiro Konishi 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Tatsuya Kamata 5-33-8 Shiba, Minato-ku, Tokyo (56) References JP-A-8-170680 (JP, A) JP-A-5-58032 (JP, U) JP-A-59-21147 (JP, U) U.S. Pat. , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F16F 9/00-9/58 F16F 15/02

Claims (7)

(57) [Claims] 1. A shock absorber interposed between a vehicle body and a wheel, comprising: a movable mass for sensing a vertical movement of the vehicle body; and a movable mass floating in a predetermined neutral position. A vibration sensing mechanism including a mass spring system including a biasing means for supporting, and an interlocking member that interlocks with the vertical movement of the movable mass, and has a damping force according to the vertical position of the movable mass. Variably controlled damping force generating section, wherein the biasing means is disposed below the movable mass and pushes up the movable mass to the neutral position side; and above the movable mass And a second spring that pushes down the movable mass to the neutral position side, wherein the vibration sensing mechanism is provided inside or on the piston rod.
The movable mass is formed inside the casing and accommodated therein.
An inner chamber, a flow control unit provided on an outer peripheral portion of the movable mass, and the first case partitioned by the inner chamber and the flow control unit.
A first small liquid chamber formed on the side of the neck, the internal chamber and the flow control section,
Variable damping force shock absorber, characterized in that it comprises a second small liquid chamber formed roots side. 2. The shock absorber according to claim 1, wherein said vibration sensing mechanism is housed inside a piston rod of the shock absorber. 3. The shock absorber according to claim 1, wherein said vibration sensing mechanism is housed in a casing provided on an upper end side of a piston rod of the shock absorber. 4. A biasing means of the vibration sensing mechanism, wherein the movable mass is set at the neutral position by applying an initial deflection to the first and second springs when the movable mass is at the neutral position. A regulating member for holding the centering force applied thereto.
4. The shock absorber according to any one of 3. 5. The lower spring is held by the regulating member in a state where it is initially bent so as to generate a repulsive load sufficient to push the movable mass to the neutral position against the own weight of the movable mass. And the second spring comprises:
When the movable mass rises beyond the neutral position, the movable mass is held by the restricting member in a state where initial deflection is given so as to generate a repulsive load to push the movable mass back to the neutral position. The shock absorber according to claim 4. 6. The damping force generating section has a slide member movable in the vertical direction in conjunction with the movable mass, the slide member being used when the shock absorber moves in either the extension side or the compression side. The sliding member also narrows the flow path of the flow part when the shock absorber moves to the pressure side in a state where the movable mass is relatively raised, and When the shock absorber moves to the extension side, the flow path is expanded by descending the slide member using the fluid force of the jet of the hydraulic fluid, and the shock absorber moves to the extension side when the movable mass is relatively lowered. When the slide member is raised by using the fluid force of the jet of the hydraulic fluid when the shock absorber moves to the pressure side by narrowing the flow path of the flow portion when Shock absorber according to claim 1, characterized in that it is configured to widen the road. 7. A suspension spring for forming a vehicle suspension in cooperation with the shock absorber, wherein a resonance frequency of a sprung system including the shock absorber and the suspension spring is ωs, 2. The shock absorber according to claim 1, wherein the resonance frequency ratio (.omega.d / .omega.s) is set to 2.5 or less when the resonance frequency is .omega.d.