JP3430321B2 - Damping force adjustable hydraulic 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 damping force adjustable hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile.

[0002]

2. Description of the Related Art In a hydraulic shock absorber mounted on a suspension system of a vehicle such as an automobile, a damping force can be appropriately adjusted in order to improve ride comfort and steering stability in accordance with road surface conditions, running conditions and the like. There is a damping force adjustable hydraulic shock absorber.

In this type of hydraulic shock absorber, a piston, to which a piston rod is connected, is slidably fitted in a cylinder in which an oil liquid is sealed, and two chambers in the cylinder are defined by the piston. The main oil liquid passage and the bypass passage communicate with each other, the main oil liquid passage is provided with a damping force generating mechanism (orifice, disk valve, etc.) that generates a large damping force, and the bypass passage generates a small damping force. A damping force control valve that opens and closes the generation mechanism and the bypass passage is provided.

With this configuration, when the damping force adjusting valve is opened, the oil liquid in the cylinder mainly flows through the bypass passage due to the sliding of the piston due to the expansion and contraction of the piston rod, and the small damping force is applied to both the expansion side and the compression side. Occurs, and the damping force characteristic becomes a soft characteristic. Also, when the damping force adjusting valve is closed, due to the piston sliding as the piston rod expands and contracts, the oil liquid in the cylinder flows only through the main oil liquid passage and a large damping force is generated on both the expansion side and the contraction side. The damping force characteristic becomes a hard characteristic. In this way, the damping force characteristic can be switched by opening and closing the damping force adjusting valve.

By selecting the damping force characteristic on the soft side during normal running of the vehicle, the vibration due to the unevenness of the road surface can be absorbed and the riding comfort can be improved.
By selecting the damping force characteristics on the hard side during turning, acceleration, braking, and high-speed traveling, it is possible to suppress changes in the posture of the vehicle body and improve steering stability. Furthermore, by combining a damping force adjustable hydraulic shock absorber with a control device and an actuator, the damping force is automatically switched in real time according to road conditions, running conditions, etc. to improve riding comfort and steering stability. There is a suspension control device.

In the suspension control device as described above, different types of damping force characteristics of the hydraulic shock absorber on the extension side and the contraction side are used (for example, when the extension side is a hard characteristic, the compression side is a soft characteristic). By setting the combination of soft characteristics on the extension side and hard characteristics on the contraction side, it is possible to quickly obtain an appropriate damping force for changes in road surface conditions and driving conditions, and to improve riding comfort and steering stability. It is known that it can be effectively improved.

Therefore, conventionally, two different bypass passages are provided on the extension side and the contraction side, and the passage areas of the respective bypass passages are adjusted, so that different types of damping force characteristics are obtained on the extension side and the contraction side. There have been proposed various damping force adjustable hydraulic shock absorbers capable of setting the.

[0008]

However, in the conventional damping force adjusting hydraulic shock absorber of this type, since the passage area of the bypass passage set by the damping force adjusting valve is fixed, the damping force generated is The damping force is adjusted by adjusting the damping coefficient with the piston speed as a variable, because it changes according to the magnitude of the piston speed. Therefore, in order to directly control the damping force, in the damping force control by the suspension control device as described above, first, the piston speed of the hydraulic shock absorber is detected, and the desired damping force is obtained with respect to the input of the piston speed. It is necessary to calculate a damping coefficient to be generated, and then drive the actuator so that the damping force control valve has an opening corresponding to the calculated damping coefficient. For this reason, there is a problem that the load of the control circuit is heavy and it becomes difficult to quickly switch the damping force according to changes in road surface conditions and running conditions.

Therefore, the present applicant has filed Japanese Patent Application No. 5-1414.
No. 37 proposes a damping force adjustable hydraulic shock absorber capable of directly controlling the damping force regardless of the piston speed. And the present invention further directly controls the damping force regardless of the piston speed,
An object of the present invention is to provide a damping force adjustable hydraulic shock absorber capable of generating a stable damping force even with respect to a high frequency input to a piston rod.

[0010]

[0011]

[0012]

Means for Solving the Problems] damping force of the first aspect of the present invention
The adjustable hydraulic shock absorber includes a cylinder filled with oil liquid, a piston slidably fitted in the cylinder to define two chambers in the cylinder, one end of which is connected to the piston and the other end of which is connected to the piston. A piston rod that extends to the outside of the cylinder, a communication passage that connects one chamber and the other chamber in the cylinder, and a valve that is provided in the communication passage and is opened by a unidirectional flow of oil liquid. A damping force adjusting valve having a valve body that generates a damping force, and a back pressure chamber provided on the back side of the damping force adjusting valve.
And branch from the communication passage upstream of the damping force adjusting valve.
And a back pressure passage communicating with the back pressure chamber and in series with the back pressure passage.
Of the two orifices arranged in the
Spring means provided between the valve body and the back pressure chamber
The pressure in the back pressure chamber is passed through the spring means to the valve body.
And a damping valve for adjusting the pressure of the back pressure chamber in the communication passage, which is connected between two orifices of the back pressure passage and a valve opening adjustment mechanism for changing the valve opening pressure of the valve body. And a relief valve for adjusting the pressure on the downstream side of the valve.

[0013] The damping force adjustable hydraulic shock absorber of the invention of claim 2, a cylinder hydraulic fluid sealed therein, a piston slidably fitted in the cylinder defining in the cylinder into two chambers An extension side that allows two chambers in the cylinder to communicate with a piston rod, one end of which is connected to the piston and the other end of which extends to the outside of the cylinder, and which allows the oil liquid to flow during the extension stroke of the piston rod. The communication passage communicates with the two chambers in the cylinder to allow the oil liquid to flow during the compression stroke of the piston rod, and the extension communication passage opens the valve to dampen the fluid. and stretch side damping force adjusting valve having a valve body which generates a force, a compression-side damping force adjusting valve having a valve body which generates a damping force by opening the flow of hydraulic fluid in the compression-side communication passage, wherein the elongation Side of damping force adjustment valve
The extension side back pressure chamber provided on the surface side and the extension side communication passage
From the upstream side of the extension side damping force control valve
An extension side back pressure passage communicating with the side back pressure chamber and the extension side back pressure passage
Two extension side orifices arranged in series in the path,
Between the valve body of the extension side damping force adjusting valve and the extension side back pressure chamber
An extension side spring means provided, and the extension side back pressure chamber
Is applied to the valve body via the extension side spring means.
An extension side valve opening pressure adjusting mechanism for changing the valve opening pressure of the valve body, and a compression provided on the back side of the compression side damping force adjusting valve.
Side back pressure chamber and the compression side damping force adjustment from the compression side communication passage.
Compression that branches on the upstream side of the valve and communicates with the compression-side back pressure chamber
The back pressure passage on the right side and the compression back pressure passage arranged in series 2
Two compression-side orifices and valves of the compression-side damping force adjustment valve
Compression-side spring means provided between the body and the compression-side back pressure chamber
The pressure in the compression-side back pressure chamber, and the compression-side spring hand.
Change the valve opening pressure of the valve body by acting on the valve body through a step
And a compression side valve opening pressure adjusting mechanism for connecting the two expansion side orifices, and relieving the pressure of the expansion side back pressure chamber to a downstream side of the expansion side damping force adjusting valve in the expansion side communication passage. It is connected between the extension side relief valve to be adjusted and the two compression side orifices, and the pressure in the compression side back pressure chamber is relieved and adjusted in the compression side communication passage to the downstream side of the compression side damping force control valve. The contraction side relief valve and the valve body of the extension side relief valve are biased in the valve closing direction by moving to one side, and the valve element of the compression side relief valve is biased in the valve closing direction by moving to the other side. And a proportional solenoid having a plunger.

[0014]

[0015]

[0016]

SUMMARY OF] According to the damping force adjustable hydraulic shock absorber of the invention of claim 1, during the extension or compression stroke of the piston rod, by adjusting the relief pressure of the relief valve, the back of the valve opening pressure adjusting mechanism in accordance with this adjustment Since the pressure in the pressure chamber changes and the opening of the valve body of the damping force adjusting valve is determined according to the pressure in the back pressure chamber and the pressure in the communication passage, the damping force should be controlled directly regardless of the piston speed. You can Also, the back pressure chamber is a body formed by spring means.
A first-order lag system is created by product elasticity and two orifices.
Form a low-pass filter, so the piston rod
Relief valve surging and self-excitation due to high frequency input to
Even if pulsation occurs in the oil liquid in the back pressure passage due to movement, back pressure
Room pressure rise is slowly dampened and back pressure rises excessively
Is prevented and an appropriate damping force is generated.

According to the damping force adjusting hydraulic shock absorber of the second aspect of the present invention, during the extension stroke of the piston rod, the proportional solenoid is energized to adjust the relief pressure of the extension side relief valve, and in response to this adjustment. Extension of the extension side valve opening pressure adjustment mechanism
Changes the pressure in the beauty side backpressure chamber, the opening of the extension-side damping force adjusting valve according to the pressure of the pressure and the extension-side communication passage of the extension-side backpressure chamber is determined, directly regardless piston speed The expansion side damping force can be controlled, and during the compression stroke, the relief pressure of the compression side relief valve is adjusted, and the pressure in the compression side back pressure chamber of the compression side opening pressure adjustment mechanism changes according to this adjustment. Therefore, the opening of the compression-side damping force control valve is determined according to the pressure in the compression- side back pressure chamber and the pressure in the compression-side communication passage, so it is possible to directly control the compression-side damping force regardless of the piston speed. it can. In addition, the back pressure chamber has volume elasticity and
And two orifices form a first-order lag system,
Since it forms a filter, high frequency to the piston rod
By surging of the relief valve by input or self-excited vibration
Even if pulsation occurs in the oil liquid in the back pressure passage, the pressure in the back pressure chamber
The rise is moderately dampened to prevent excessive back pressure rise
And an appropriate damping force is generated. Furthermore, since the proportional solenoid moves to one side of the plunger, the relief pressure of the extension side relief valve increases, and the movement of the proportional solenoid to the other side increases the relief pressure of the compression side relief valve. The damping force characteristic of can be set.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Reference for explaining the first embodiment of the present invention
FIG. 1 and FIG. 2 show a damping force adjusting type hydraulic shock absorber .
Will be explained. In the damping force adjusting type hydraulic shock absorber 1, a piston 3 is slidably fitted in a cylinder 2 in which an oil liquid is sealed, and the inside of the cylinder 2 is cylinder upper chamber 2a and cylinder lower chamber 2b by this piston 3. It is divided into two rooms. One end of a piston rod 4 is connected to the piston 3, and the other end of the piston rod 4 is inserted into a rod guide and a seal member (not shown) provided at the end of the cylinder 2 so that It has been extended to the outside.

The piston 3 is provided with an extension side passage 5 and a compression side passage 6 which connect the cylinder upper chamber 2a and the cylinder lower chamber 2b. The extension side passage 5 has a cylinder upper chamber.
A pressure regulating valve 7 such as a disc valve that allows a flow of oil liquid from the cylinder upper chamber 2a side to the cylinder lower chamber 2b side to generate a damping force when the inside of 2a exceeds a predetermined pressure is provided. The contraction side passage 6 is provided with a control valve such as a disk valve that allows a fluid flow from the cylinder lower chamber 2b side to the cylinder upper chamber 2a side to generate a damping force when the pressure in the cylinder lower chamber 2b exceeds a predetermined pressure. A pressure valve 8 is provided.

A communication passage 9 for communicating the cylinder upper chamber 2a and the cylinder lower chamber 2b is provided outside the cylinder 2.
In the communication passage 9, only a check valve 10 that blocks only the flow of oil liquid from the cylinder upper chamber 2a side to the cylinder lower chamber 2b side and the flow of oil liquid only from the cylinder lower chamber 2b side to the cylinder upper chamber 2a side are provided. A check valve 11 is provided to prevent this. In the communication passage 9, the extension side communication passage 12 that bypasses the check valve 10 and the check valve
A contraction side communication passage 13 that bypasses 11 is provided.
Further, in the communication passage 9, a reservoir 14 (accumulator) that compensates for a volume change in the cylinder 2 due to expansion and contraction of the piston rod 4 by compressing and expanding gas is provided with an orifice 15 and a check valve 16 arranged in parallel with each other. Connected through.

The extension side communication passage 12 is provided with a poppet valve 17 as an extension side damping force adjusting valve. Poppet valve 17
Has a poppet 19 which is a valve body slidably fitted in the guide 18, and the movement of the poppet 19 causes the expansion side passage 12 to move.
The passage area of is adjusted. Poppet 19
Receives the pressure on the upstream side (the cylinder upper chamber 2a side) in the extension side communication passage 12 and moves in the valve opening direction. Further, a back pressure chamber 20 that constitutes a valve opening pressure adjusting mechanism is provided on the back side of the poppet 19 in the guide 18, and the pressure in the back pressure chamber 20 acts in the direction to close the poppet 19. It is like this. In the back pressure chamber 20, a spring 21 that biases the poppet 19 in the valve closing direction is provided.

The back pressure chamber 20 is connected to the upstream side (the cylinder upper chamber 2a side) of the poppet valve 17 in the extension side passage 12 by the back pressure passage 22. An orifice 23 is provided in the back pressure passage 22. The downstream side of the orifice 23 of the back pressure passage 22 is connected to an extension side relief valve 25 of an electromagnetic proportional control valve 24 described later, and further, via a relief passage 26, a downstream side of the poppet valve 17 of the extension side passage 12 ( It communicates with the reservoir 14 side).

Similarly, the compression side communication passage 13 is provided with a poppet valve 27 as a compression side damping force adjusting valve. In the poppet valve 27, a poppet 29 which is a valve body is slidably fitted in a guide 28, and the passage area of the contraction side passage 13 is adjusted by the movement of the poppet 29. The poppet 29 is on the upstream side of the compression side communication passage 13 (on the side of the lower cylinder chamber 2b).
It is designed to move in the valve opening direction under the pressure of.
A back pressure chamber 30 that constitutes a valve opening pressure adjusting mechanism is provided on the back side of the poppet 29 in the guide 28.
The pressure inside acts to close the poppet 29. In the back pressure chamber 30, a spring 31 that biases the poppet 29 in the valve closing direction is provided.

The back pressure chamber 30 is connected to the upstream side (the cylinder lower chamber 2b side) of the poppet valve 27 in the compression side communication passage 13 by the back pressure passage 32. An orifice 33 is provided in the back pressure passage 32. The downstream side of the orifice 33 of the back pressure passage 32 is connected to the compression side relief valve 34 of the electromagnetic proportional control valve 24, and further, via the relief passage 26, the downstream side of the poppet valve 27 of the compression side passage 13 (the reservoir 14 Side).

Next, the electromagnetic proportional control valve 24 will be described with reference to FIG. As shown in FIG. 2, the electromagnetic proportional control valve 24
Is an extension side relief valve 25 for relief of a passage 35 connected to the back pressure passage 22, a compression side relief valve 34 for relief of a passage 36 connected to the back pressure passage 32, and an extension side relief valve 25.
And a proportional solenoid 37 for adjusting the relief pressure of the compression side relief valve 34.

The extension side relief valve 25 is a needle valve which opens and closes a communication passage between the passage 35 and the relief chamber 38 by a needle 39 which is a valve body. Similarly, the contraction side relief valve 34 is
The communication passage between the passage 36 and the relief chamber 40 is formed by a needle that is a valve element.
It is a needle valve that opens and closes by 41. Needle 39, 41
Are connected to both ends of an operating rod 43 connected to the plunger 42 of the proportional solenoid 37 via spring members 44 and 45 as spring means, respectively. And working rod
The movement of 43 compresses the spring member 44 or the spring member 45 to increase the relief pressure of either the expansion side relief valve 25 or the contraction side relief valve 34, and the relief pressure of the other decreases. Where the needles 39 and 40
Has a sufficiently small mass (about 1 g or less), and the natural frequency of the vibration system combined with the spring members 44 and 45 is sufficiently high (kH
z order).

The proportional solenoid 37 is provided with a spring 46 that urges the actuating rod 43 toward the contraction side relief valve 34 side. The proportional solenoid 37 moves the plunger according to the applied current.
The actuating rod 43 is stretched via 42 against the biasing force of the spring 46.
A force is generated to move the side relief valve 25 . Then, the compression amount of the spring member 45 is changed according to the energizing current to adjust the relief pressure of the compression-side relief valve 34, and the energizing current is increased to increase the operating rod 43.
Is moved to the extension side relief valve 25 side, the spring member 44 is compressed, and the relief pressure of the extension side relief valve 25 can be adjusted.

The relief chamber 38 and the relief chamber 40 are communicated with each other via a passage 47 in the proportional solenoid 37,
These are connected to the reservoir 14 side via a relief passage 26.

The damping force adjusting type hydraulic slack configured as described above
The operation of the impactor 1 will be described below.

During the extension stroke of the piston rod 4, the sliding of the piston 3 causes the oil liquid on the cylinder upper chamber 2a side to flow through the communication passage 9 to the cylinder lower chamber 2b side.
10 is closed and the check valve 11 is opened, so
A damping force is generated by the poppet valve 17 by flowing through the. At this time, since the oil liquid corresponding to the piston rod 4 withdrawing from the cylinder upper chamber 2a is smoothly supplied to the cylinder lower chamber 2b side from the reservoir 14 by opening the check valve, the cylinder lower chamber 2b side becomes excessively negative. There is no pressure, and it is possible to prevent bubbles from entering.

In the poppet valve 17, the pressure on the cylinder upper chamber 2a side acts to move the poppet 19 in the valve opening direction. On the other hand, the pressure on the cylinder upper chamber 2a side acts on the back pressure chamber 20 through the back pressure passage 22 to move the poppet 19 in the valve closing direction. The pressure in the back pressure chamber 20 is the electromagnetic proportional control valve 24.
When the pressure exceeds the set pressure of the extension side relief valve 25, the needle 39 moves against the elastic force of the spring member 44, and the oil liquid in the back pressure passage 22 is relieved to the relief passage 26. The pressure can be arbitrarily set by the set pressure of the expansion side relief valve 25 of the electromagnetic proportional control valve. Then, the poppet 19 has a pressure on the cylinder upper chamber 2a side and an extension side relief valve 25.
It moves to a position where the set pressure and the urging force of the spring 21 are balanced. Therefore, the poppet valve 17 is opened at an opening degree corresponding to the pressure of the cylinder upper chamber 2a, and the damping force is determined.
In this way, the passage area of the poppet valve 17 changes according to the pressure in the cylinder upper chamber 2a, and a predetermined damping force is generated regardless of the piston speed.

During the compression stroke of the piston rod 4, the sliding of the piston 3 causes the oil liquid on the cylinder lower chamber 2b side to flow through the communication passage 9 to the cylinder upper chamber 2a side.
Since 10 opens and the check valve 11 closes, the oil liquid contracts and the side communication passage
A damping force is generated by the poppet valve 27 by flowing through 13. At this time, the piston rod 4 moves into the cylinder upper chamber 2a.
The oil liquid that has entered the inside is absorbed by the reservoir 14. Here, since the orifice 15 provides an appropriate resistance to the flow of the oil liquid to the reservoir 14, the cylinder upper chamber 2a side does not become excessively negative pressure, and it is possible to prevent the inclusion of bubbles. .

In the poppet valve 27, as in the case of the poppet valve 17 on the extension side, the poppet 29 prevents the pressure on the cylinder lower chamber 2b side, the set pressure of the compression side relief valve 34 of the electromagnetic proportional control valve 24, and the spring 31. The damping force is determined by moving to a balanced position and opening the valve at an opening degree according to the pressure in the cylinder lower chamber 2b. In this way, the passage area of the poppet valve 27 changes according to the pressure in the cylinder lower chamber 2b, and a predetermined damping force is generated regardless of the piston speed.

Then, the proportional solenoid 37 of the electromagnetic proportional control valve 24 is energized to position the operating rod 43 on the compression side relief valve 34 side and adjust the relief pressure of the compression side relief valve 34, whereby the poppet valve 27 The opening degree of is adjusted, and the damping force on the contraction side can be controlled. At this time, the relief pressure of the extension side relief valve 25 becomes low, so the poppet valve 17
And the damping force on the extension side becomes smaller. Therefore, the damping force characteristics are hard characteristics on the contracting side,
The stretch side has soft characteristics.

Further, the current supplied to the proportional solenoid 37 is increased to move the operating rod 43 to the extension side relief valve 25 side, and the spring member 44 is compressed to adjust the relief pressure of the extension side relief valve 25. The opening degree of the poppet valve 17 is adjusted, and the extension side damping force can be controlled. At this time, since the relief pressure of the compression side relief valve 34 becomes low, the opening degree of the poppet valve 27 becomes large and the compression force at the compression side becomes small. Therefore, regarding the damping force characteristic, the extension side has a hard characteristic and the contraction side has a soft characteristic.

In this way, by adjusting the current supplied to the proportional solenoid 37, the damping force on the contraction side is continuously changed from the hard side to the soft side, and the extension side damping force characteristic is changed to the soft side. Can be continuously changed from the hard side. At this time, different types of damping force are generated on the extension side and the contraction side, and damping force characteristics suitable for suspension control can be obtained.

When the pressure in the cylinder upper chamber 2a exceeds a predetermined value during the extension stroke, the pressure regulating valve 7 of the piston 3 is opened and the oil liquid in the cylinder upper chamber 2a passes directly through the extension side passage 5 into the cylinder. A damping force is generated by flowing into the lower chamber 2b. Similarly, when the pressure in the cylinder lower chamber 2b becomes equal to or higher than a predetermined value during the compression stroke, the pressure regulating valve 8 of the piston 3 opens and the oil liquid in the cylinder lower chamber 2b passes directly through the compression side passage 6 into the cylinder upper chamber. A damping force is generated by flowing to 2a.

Further, the needle 39 of the electromagnetic proportional control valve 24,
Since 41 has a sufficiently small mass to sufficiently increase the natural frequency of the vibration system in combination with the spring members 44 and 45, the spring member 41 responds to a sudden increase in pressure in the back pressure passages 22 and 32. Four
Back pressure passage 2 by opening valves 4 and 45 without any delay due to bending
The rise of back pressure due to the pulsation of oil liquid in 2, 32 can be suppressed. Then, the rise in back pressure due to pulsation can be suppressed within 1 millisecond. Furthermore, since the operating rod 43 and the plunger 42 are not moved when the needles 39 and 41 are opened, it is possible to prevent a delay in response due to the inertial mass and solid friction. Therefore, it is possible to suppress an increase in back pressure due to pulsation and generate an appropriate damping force with respect to a change in the piston speed (input speed to the piston rod) of a high frequency, and prevent deterioration of the riding comfort of the vehicle. be able to.

The control of the relief pressure of the expansion side relief valve 25 and the contraction side relief valve 34 by the current supplied to the proportional solenoid 37 is performed by the operating rod 43 by the spring members 44, 45.
Since it is performed by bending the spring, a response delay of about tens of milliseconds may occur due to the spring element, but the damping force adjustment for sprung and unsprung vibrations in normal suspension control is about 1 to 10 Hz. Since it is done in terms of numbers, the response lag due to the spring element is not a problem.

Next, to explain the second embodiment of the present invention.
The damping force adjustable hydraulic shock absorber referred to in FIG. 3 will be described with reference to FIG.

As shown in FIG. 3, the damping force adjusting type hydraulic shock absorber 48 has a triple tube structure in which an inner cylinder 50 is provided outside the cylinder 49 and an outer cylinder 51 is provided outside the inner cylinder 50. Has become
An annular passage 52 is formed between the cylinder 49 and the inner cylinder 50,
A reservoir chamber 53 is formed between the inner cylinder 50 and the outer cylinder 51.

A piston 54 is slidably fitted in the cylinder 49, and the cylinder 54 is fitted by the piston 54.
The inside is divided into two chambers, a cylinder upper chamber 49a and a cylinder lower chamber 49b. One end of a piston rod 55 is connected to the piston 54 by a nut 56, and
The other end of 55 extends through the rod guide 57 and the seal member 58 provided at the upper end of the cylinder 49 to the outside of the cylinder 49. A base valve 59 is provided at the lower end of the cylinder 49, and the cylinder lower chamber 49b and the reservoir chamber 53 are connected to each other with an appropriate flow resistance via the base valve 59. The cylinder 49 is filled with oil liquid, the reservoir chamber 53 is filled with oil liquid and gas, and the volume change in the cylinder 49 due to expansion and contraction of the piston rod 55 is compressed by the gas in the reservoir chamber 53. , It is designed to compensate by expansion.

The piston 54 is provided with an extension side passage 60 and a contraction side passage 61 which connect the cylinder upper chamber 49a and the cylinder lower chamber 49b. The extension side passage 60 has a cylinder upper chamber 49a when the pressure in the cylinder upper chamber 49a exceeds a predetermined value.
A disc valve 62 that allows the flow of oil liquid from the a side to the cylinder lower chamber 2b side to generate a damping force is provided.
When the pressure in the cylinder lower chamber 49b exceeds a predetermined value, the contraction side passage 61 moves from the cylinder lower chamber 49b side to the cylinder upper chamber 49a.
A disc valve 63 is provided which allows the oil liquid to flow to the side and generates a damping force.

A substantially cylindrical passage member 64 is fitted around the lower end of the cylinder 49, and the inner cylinder 50 and the outer cylinder are joined together.
The lower end of 51 is fitted in the upper end of the passage member 64. The annular passage 52 extends between the cylinder 49 and the passage member 64, and the reservoir passage 53 axially penetrates the side wall of the passage member 64 so that the reservoir chamber 53 passes through the base valve 59 and the cylinder lower chamber 49b. Is in communication with.

An extension-side damping force adjusting mechanism 66 and an annular passage 52, which form an extension-side communication passage that connects the cylinder upper chamber 49a and the cylinder lower chamber 49b via the annular passage 52, are provided on the side surface of the passage member 64. Cylinder upper chamber 49a and cylinder lower chamber
A compression-side damping force adjusting mechanism 67 that constitutes a compression-side communication path that communicates with the valve 49b is provided. Extension side damping force generation mechanism
The bottom portion of a valve case 68 having a bottomed tubular shape is coupled to the side wall of the passage member 64, and a tubular plug 69 having a bottomed tubular shape is screwed into the opening of the valve case 68 so that the valve 66 is mounted inside the valve case 68. A chamber 68a is formed. At the bottom of the valve case 68,
A valve chamber is provided through a passage 70 provided on a side wall of the passage member 64.
A valve passage 71 and a guide hole 72 are provided for communicating the 68a with the annular passage 52.
Is communicated with the cylinder upper chamber 49a by a passage 73 provided in a side wall near the upper end of the cylinder. In addition, the valve case 68
A communication passage 76 for communicating the cylinder lower chamber 49b and the valve chamber 68a with each other through a passage 74 provided on the side wall of the passage member 64 and a passage 75 provided on the side wall near the lower end of the cylinder 49 is provided at the bottom of the. It is provided.

Inside the bottom of the valve case 68, a disc valve is provided as a damping force adjusting valve for generating a damping force by allowing only oil liquid to flow from the cylinder upper chamber 49a side of the valve passage 71 to the valve chamber 68a side. 77 are provided. Guide hole
The small diameter part on the tip side of the plunger 78 is slidably fitted into the 72, and the large diameter part on the base end side of the plunger 78 is plug 69.
It is slidably fitted in the guide hole 79 provided in
A back pressure chamber 79a forming a valve opening pressure adjusting mechanism is formed in the guide hole 79. A back pressure passage 80 extends through the plunger 78 along its axis, and the back pressure passage 80 is provided with an orifice 81. Then, the orifice 81 reduces the pressure of the oil liquid flowing to the back pressure passage 80, and a relief valve to be described later.
We try to reduce the burden on 82.

The plug 69 is provided with a relief valve 82 for relieving the pressure in the back pressure chamber 79a. Relief valve 82
The proportional solenoid 83 is attached to the opening of the plug 69, and the communication passage 85 for communicating between the relief chamber 84 formed in the plug 69 and the back pressure chamber 79a is connected to the operating rod of the proportional solenoid 83.
A needle valve that is opened and closed by a needle 86 that is a valve body connected to 83a via a spring member 83b as spring means. The proportional solenoid 83 adjusts the relief pressure of the relief valve 82 by changing the valve opening pressure of the needle 86 by urging the actuating rod 83a with a force according to the applied current to compress the spring member 83b. ing. The relief room 84 is
The relief passage 87 communicates with the valve chamber 68a. Here, the needle 86 has a sufficiently small mass (about 1 g).
In the following, the natural frequency of the vibration system combined with the spring member 83b is sufficiently high (kHz order).

A pressing member 88 that contacts the back side of the disc valve 77 is connected to the plunger 78, and the plunger 78 presses the disc valve 77 in the valve closing direction by the pressure received from the back pressure chamber 79a. By this pressing, the valve opening pressure of the disc valve 77 is adjusted.

The contraction side damping force adjusting mechanism 67 has a bottom of a bottomed tubular valve case 89 coupled to the side wall of the passage member 64, and a bottomed tubular plug 90 is screwed into the opening of the valve case 89. A valve chamber 89a is formed in the valve case 89 by being attached. A valve that connects the valve chamber 89a and the cylinder lower chamber 49b to the bottom of the valve case 89 via a passage 91 provided in a side wall near the lower end of the cylinder 49 and a passage 92 provided in a side wall of the passage member 64. A passage 93 and a guide hole 94 are provided. Furthermore, at the bottom of the valve case 89,
The valve chamber is provided through a passage 95 provided on the side wall of the passage member 64.
A communication passage 96 is provided for communicating the 89a with the annular passage 52.

Inside the bottom of the valve case 89, a disc valve is provided as a damping force adjusting valve that allows only the flow of oil liquid from the cylinder lower chamber 49b side of the valve passage 93 to the valve chamber 89a side to generate a damping force. 97 is provided. Guide hole
The small diameter part on the tip side of the plunger 98 is slidably fitted to the 94, and the large diameter part on the base end side of the plunger 98 is plug 90.
It is slidably fitted in the guide hole 99 provided in
A back pressure chamber 99a forming a valve opening pressure adjusting mechanism is formed in the guide hole 99. A back pressure passage 100 extends through the plunger 98 along its axis, and an orifice 101 is provided in the back pressure passage 100. And the orifice 101
The oil liquid flowing to the back pressure passage 100 is decompressed to reduce the load on the relief valve 102 described later.

The plug 90 is provided with a relief valve 102 for relieving the pressure in the back pressure chamber 99a. Relief valve
The proportional solenoid 103 is provided with a communication passage 105 that connects the relief chamber 104 formed in the plug 90 and the back pressure chamber 99a with the proportional solenoid 103 attached to the opening of the plug 90.
Is a needle valve which is opened and closed by a needle 106 which is a valve body connected to the operating rod 103a of the above through a spring member 103b as spring means. The proportional solenoid 103 adjusts the relief pressure of the relief valve 102 by changing the valve opening pressure of the needle 106 by urging the actuating rod 103a with a force according to the applied current and compressing the spring 103b. There is. The relief chamber 104 is connected to the valve chamber 89a by a relief passage 107. Where the needle 106 is
The mass is made sufficiently small (about 1 g or less), and the natural frequency of the vibration system combined with the spring 103b is made sufficiently high (kHz order).

The plunger 98 is connected with a pressing member 108 that abuts on the back side of the disc valve 97, and the plunger 98
The disk valve 97 is pressed in the valve closing direction by the pressure received from the back pressure chamber 99a, and the valve opening pressure of the disk valve 97 is adjusted by this pressing.

The damping force adjusting type hydraulic slack configured as described above
The operation of the impactor 48 will be described below.

During the extension stroke of the piston rod 55, the piston 54 slides to allow the oil liquid on the cylinder upper chamber 49a side to pass through.
73, passing through the annular passage 52, and further the extension side damping force adjusting mechanism
66 passage 70, valve passage 71, valve chamber 68a, communication passage 76,
Flows to the cylinder lower chamber 49b side through the passages 74 and 75.
Then, the disc valve 77 is opened by the pressure of the oil liquid on the cylinder upper chamber 49a side, and the passage area of the valve passage 71 is adjusted to generate a damping force. At this time, the disc valve 77 is pressed in the valve closing direction by the pressing member 88, so that a damping force proportional to the pressing load is generated. on the other hand,
In the compression-side damping adjusting mechanism 67, the disc valve 97 and the relief valve 102 are closed by the pressure on the cylinder upper chamber 49a side, so that the oil liquid does not flow.

The pressing load applied by the pressing member 88 is that the oil liquid on the cylinder upper chamber 49a side is transmitted to the back pressure chamber 79a via the back pressure passage 80 of the plunger 78, and the pressure of the oil liquid in the back pressure chamber 79a is transferred to the plunger 78. It is caused by acting on the pressure receiving surface of the large diameter part of the. At this time, when the pressure in the back pressure chamber 79a exceeds the set pressure of the relief valve 82, the relief valve 82 opens and the oil liquid in the back pressure chamber 79a is relieved to the relief chamber 84 and passes through the relief passage 87 to the cylinder lower chamber 49b side. Flow into the valve chamber 68a of the
The pressure of 79a can be arbitrarily set by the relief valve 82. Therefore, the damping force can be directly controlled by changing the compression amount of the spring member 83b and adjusting the valve opening pressure of the needle 86 and setting the relief pressure of the relief valve 82 by the current supplied to the proportional solenoid 83. The opening degree of the disc valve 77 changes according to the pressure in the cylinder upper chamber 49a, and a predetermined damping force is generated regardless of the piston speed.

When the pressure in the cylinder upper chamber 49a exceeds a predetermined value, the disc valve 62 of the piston 54 opens and the oil liquid in the cylinder upper chamber 49a passes directly through the extension side passage 60 and directly into the cylinder lower chamber 49b. A damping force is generated by flowing to.

During the compression stroke of the piston rod 55, the piston 54 slides to allow the oil liquid in the cylinder lower chamber 49b to pass through the passage.
Passing through 91, the passage 92 of the compression side damping force adjusting mechanism 67, the valve passage 93, the valve chamber 89a, the communication passage 96, the passage 95, the annular passage 52,
Flows through the passage 73 to the cylinder upper chamber 49a. Then, the disc valve 97 is driven by the pressure of the oil liquid on the cylinder lower chamber 49b side.
The valve is opened to adjust the passage area of the valve passage 93, so that a damping force is generated. At this time, the disc valve 97
Is pressed in the valve closing direction by the pressing member 108, so that a damping force proportional to the pressing load is generated. On the other hand, in the extension-side damping adjustment mechanism 66, the disc valve 77 and the relief valve 82 are closed by the pressure on the cylinder lower chamber 49b side, so that the oil liquid does not flow.

The pressing load of the pressing member 108 causes the oil liquid on the cylinder lower chamber 49b side to be transmitted to the back pressure chamber 99a via the back pressure passage 100 of the plunger 98, and the pressure of the oil liquid in the back pressure chamber 99a is changed to the plunger 98. It is caused by acting on the pressure receiving surface of the large diameter part of the. At this time, when the pressure in the back pressure chamber 99a exceeds the set pressure of the relief valve 102, the relief valve 102 opens and the oil liquid in the back pressure chamber 99a is relieved to the relief chamber 104, and the relief passage 107
Since it flows through to the valve chamber 89a on the cylinder upper chamber 49a side, the pressure in the back pressure chamber 99a can be arbitrarily set by the relief valve 102. Therefore, the proportional solenoid 10
The damping force can be directly controlled by changing the compression amount of the spring 103b by adjusting the valve opening pressure of the needle 106 by setting the relief pressure of the relief valve 102 by the current supplied to the cylinder 3, and the cylinder lower chamber 49b Disc valve depending on pressure
The opening of 97 changes and a predetermined damping force is generated regardless of the piston speed.

When the pressure in the lower cylinder chamber 49b exceeds a predetermined value, the disc valve 63 of the piston 54 opens and the oil liquid in the lower cylinder chamber 49b passes directly through the contraction side passage 61 to the upper cylinder chamber 49a. A damping force is generated by flowing to.

Thus, by adjusting the relief pressures of the relief valves 87 and 102 by the currents supplied to the proportional solenoids 83 and 103, the damping forces on the extension side and the compression side can be directly controlled regardless of the piston speed. You can Further, like the damping force adjusting hydraulic shock absorber 1 described above , since the natural frequencies of the needles 86, 106 and the spring members 83b, 103b are sufficiently large, the increase in back pressure due to the response delay of the relief valve is suppressed. As a result, it is possible to prevent deterioration of the riding comfort of the vehicle.

In the damping force adjusting hydraulic shock absorber 48 , an example in which both the extension side and contraction side damping force adjusting mechanisms 66, 67 are provided is shown, but either one is used for weight reduction and simplification of specifications. Only one of them may be provided.

Next, a first embodiment of the present invention will be described with reference to FIGS. 4 and 5. The first embodiment is shown in FIG.
And for the damping force adjustable hydraulic shock absorber 1 shown in FIG.
Only the poppet valve and the relief valve are different,
Hereinafter, the same members as those of the damping force adjusting hydraulic shock absorber 1 will be denoted by the same reference numerals and only different portions will be described in detail.

As shown in FIG. 4, in the damping force adjusting hydraulic shock absorber 109 of the first embodiment, the poppet valve 17 provided in the extension passage 12 has a piston 110 on the back side of the poppet 19 in the guide 18. Is slidably fitted, and a spring member 111 as spring means is interposed between the poppet 19 and the piston 110. A back pressure chamber 20 that constitutes a valve opening pressure adjusting mechanism is formed on the back side of the piston 110.

Similarly, the poppet valve 27 provided in the contraction side passage 13 has a piston on the back side of the poppet 29 in the guide 28.
112 is slidably fitted, and a spring member 113 as spring means is interposed between the poppet 19 and the piston 112. A back pressure chamber 30 that constitutes a valve opening pressure adjusting mechanism is formed on the back side of the piston 112.

The back pressure passage 22 is provided with an orifice 115 on the downstream side of the orifice 23 and has two orifices 23, 115.
A relief valve 114 is connected between the two. Relief valve 11
4, the relief pressure can be arbitrarily set, and the relief oil liquid is made to flow to the downstream side (reservoir 14 side) of the poppet valve 17 in the extension side passage 12 by the relief passage 26. Further, the orifice 23 reduces the pressure of the oil liquid flowing to the back pressure passage 22 to reduce the burden on the relief valve 114.

Similarly, in the back pressure passage 32, an orifice 117 is provided on the downstream side of the orifice 33, and two orifices are provided.
A relief valve 116 is connected between 33 and 117. The relief valve 117 is configured so that the relief pressure can be arbitrarily set, and the relief oil 26 causes the relief passage 26 to compress the relief liquid fluid in the contraction side passage 13 downstream of the poppet valve 27 (reservoir 14
Side). In addition, the relief valve 11 reduces the pressure of the oil liquid flowing to the back pressure passage 32 by the orifice 33.
The burden of 7 is reduced.

The operation of the first embodiment constructed as above will be described below.

Damping force adjusting hydraulic shock absorber 109 of the first embodiment
Then, on the extension side of the piston rod 4, the pressure in the back pressure chamber 20 of the poppet valve 19 can be arbitrarily set by the relief pressure of the relief valve 114. Then, the poppet 19 moves to a position where the pressure on the cylinder upper chamber 2a side and the pressure in the back pressure chamber 20, that is, the set pressure of the relief valve 114, are balanced. Therefore, the poppet valve 17 is opened at an opening degree corresponding to the pressure of the cylinder upper chamber 2a, and the damping force is determined. In this way, the passage area of the poppet valve 17 changes according to the pressure in the cylinder upper chamber 2a, and a predetermined damping force is generated regardless of the piston speed.

The relief side of the piston rod 4 is a relief valve.
The pressure in the back pressure chamber 30 of the poppet valve 27 can be arbitrarily set by the relief pressure of 116. And poppet 29
Moves to a position where the pressure on the cylinder lower chamber 2b side and the pressure in the back pressure chamber 30, that is, the set pressure of the relief valve 116, are balanced. Therefore, the poppet valve 27 is opened at an opening degree corresponding to the pressure in the cylinder lower chamber 2b, and the damping force is determined. In this way, depending on the pressure in the cylinder lower chamber 2b, the poppet valve
The passage area of 27 changes and a predetermined damping force is generated regardless of the piston speed.

By adjusting the relief pressures of the relief valves 114 and 116 as described above, the damping forces on the extension side and the compression side can be directly controlled regardless of the piston speed.

Further, the pistons 110 and 112 and the spring member
Since the back pressure chambers 20 and 30 have volume elasticity by 111 and 113, the amount ΔV of the oil liquid flowing into the back pressure chambers 20 and 30 from the back pressure passages 22 and 32 and the inside of the back pressure chambers 20 and 30. Increase in pressure Δ
The relationship with P is ΔP / ΔV = 1 / (V ₀ / K _V + S ² / K _S ) = K V ₀ : volume of the back pressure chamber, K _V : bulk elastic coefficient of oil liquid, S:
The cross-sectional area of the piston, K _{S is} the spring constant of the spring member, and K is the bulk elastic modulus of the back pressure chamber. Here, when a normal metal spring is used as the spring members 111 and 113, the second term (S ² / K _S ) of the denominator of the equation is used.
Is sufficiently larger than the first term (V ₀ / K _V ) (100
Therefore, the bulk modulus K of the back pressure chamber can be set to be sufficiently small. Further, the influence of the fluctuation of the bulk elastic coefficient K _V of the oil liquid due to the inclusion and separation of bubbles in the oil liquid becomes sufficiently small, and the bulk elastic modulus K becomes a stable value.

Orifices are provided in the back pressure passages 22 and 32.
115 and 117 are provided, the relief pressure P _i of the relief valves 114 and 116, the flow rate q of the oil liquid flowing to the back pressure chambers 20 and 30 through the orifices 115 and 117, and the back pressure chambers 20 and 30. The relationship with the pressure P ₀ depends on the orifice (pressure loss-flow rate).
By linearly approximating the characteristic (resistance coefficient R), it can be expressed by the following equation. _{P i (t) -P 0 (} t) = Rq (t)

[Equation 1] By the Laplace transform, the transfer function P ₀ (s) / P _i (s) becomes as follows. G (s) = P ₀ (s) / P _i (s) = 1 / (1 + s · R / K) As shown by the above equation, the pressure P _{0 of the} back pressure chamber with respect to the relief pressure P _i is It becomes a first-order lag system, and its time constant is τ = R
A low-pass filter determined by / K is formed.
Therefore, even if pulsation occurs in the oil liquid in the back pressure passages 22 and 32 due to surging of the relief valves 114 and 116 due to high frequency input to the piston rod 4 and self-excited vibration, the back pressure chamber 2
Since the rise of the pressures of 0 and 30 is gently attenuated, it is possible to prevent an excessive rise of the back pressure of the poppet valves 17 and 27 and generate an appropriate damping force.

In this case, the relationship between the piston speed frequency ω and the damping force F by the poppet valves 17 and 27 is as shown in FIG. In FIG. 7, indicates a hard characteristic (maximum damping force) and indicates a soft characteristic (minimum damping force). Then, omega ₁ is the sprung resonance frequency of the vehicle damping force adjustable hydraulic shock absorber 109 is attached, omega ₂ shows a cut-off frequency determined by the time constant tau, enough around the sprung resonance frequency omega ₁ A large damping force can be generated, and the suspension controller can control the damping force to effectively perform posture control and vibration control. Damping is performed at a frequency ω ₃ higher than the unsprung resonance frequency. Since the damping force decreases regardless of the setting of the force characteristic, vibration under the spring can be insulated and the riding comfort can be improved.

The damping force adjustable hydraulic shock absorber 109 shown in FIG.
In the above, the electromagnetic proportional control valve 118 shown in FIG. 5 can be used instead of the relief valves 114 and 116. The electromagnetic proportional control valve 118 is different from the electromagnetic proportional control valve 24 shown in FIG. 2 in that the springs 44 and 45 are omitted.
121 and 121 are integrally formed, and the relief pressures of the extension side relief valve 25 and the contraction side relief valve 34 are directly controlled by the thrust of the solenoid 37. In this case, similarly to the damping force adjusting type hydraulic shock absorber 1 , by adjusting the current supplied to the proportional solenoid 37, the damping force on the contraction side is continuously changed from the hard side to the soft side. At the same time, the damping force characteristic on the extension side can be continuously changed from the soft side to the hard side. At this time, different types of damping force are generated on the extension side and the contraction side, and damping force characteristics suitable for suspension control can be obtained.

Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment differs from the damping force adjusting hydraulic shock absorber 48 shown in FIG. 3 only in the needle valve structure of the relief valves 82 and 102 and the valve opening pressure adjusting mechanism of the disc valves 77 and 97. Hereinafter, the same members as those shown in FIG. 3 are designated by the same reference numerals, and only different portions will be described in detail.

As shown in FIG. 6, in the damping force adjusting hydraulic shock absorber 122 of the second embodiment, the spring members 83b of the relief valves 82, 102 are different from the damping force adjusting hydraulic shock absorber 48 shown in FIG.
By omitting 103b, the operating rod 83a of the proportional solenoid 83 and the needle 86, and the operating rod of the proportional solenoid 103 are omitted.
103a and needle 106 are integrally formed to form a proportional solenoid.
The relief pressure of the relief valves 82 and 102 is directly controlled by the thrust of 83 and 103.

In the extension side damping force generating mechanism 66, the back pressure passage 123 extended from the plug 69 is fitted in the guide hole 72 provided in the valve case 68, and the back pressure passage 123 is provided at the tip thereof. An orifice 124 is provided. A plunger 125 is slidably fitted in the guide hole 79 of the plug 69, and a back pressure chamber 79a that constitutes a valve opening pressure adjusting mechanism is formed in the guide hole 79. 123 is penetrated. The back pressure passage 123 communicates with the back pressure chamber 79a via the orifice 126. A relief valve 82 connected between the two orifices 124 and 126 relieves the pressure in the back pressure passage 123, that is, the pressure in the back pressure chamber 79a. The orifice 124 reduces the pressure of the oil liquid flowing from the cylinder upper chamber 49a side to the back pressure passage 123 so that the burden on the relief valve 82 is reduced.

A spring seat 127 is attached to the plunger 125, and a spring member 128 is interposed between the spring seat 127 and the disc valve 77. And the plunger 125
Presses the disc valve 77 in the valve closing direction by the pressure received from the back pressure chamber 79a to adjust the passage area, and the elastic force of the spring member 128 as the spring means causes the back pressure chamber 79a to have a volume elasticity. To have.

Similarly, in the compression-side damping force generating mechanism 67, the back pressure passage 129 extending from the plug 90 is fitted in the guide hole 94 provided in the valve case 89, and the back pressure passage is formed.
An orifice 130 is provided at the tip of 129. A plunger 131 is slidably fitted in the guide hole 99 of the plug 90, and a back pressure chamber 99a that constitutes a valve opening pressure adjusting mechanism is formed in the guide hole 99, and the plunger 131 has a back pressure passage.
129 is penetrated. The back pressure passage 129 is the orifice 13
It is communicated with the back pressure chamber 99a via 2. The relief valve 10 connected between the two orifices 130 and 132
2 relieves the pressure in the back pressure passage 129, that is, the pressure in the back pressure chamber 99a. The orifice
130 reduces the pressure of the oil liquid flowing from the cylinder lower chamber 49b side to the back pressure passage 129 so that the relief valve 102 is less burdened.

A spring seat 133 is attached to the plunger 131, and a spring member 134 as a spring means is interposed between the spring seat 133 and the disc valve 97. The pressure received by the plunger 131 from the back pressure chamber 99a presses the disc valve 97 in the valve closing direction to adjust the passage area, and the elastic force of the spring member 134 causes the back pressure chamber 99a to have a volume elasticity. To have.

With the above configuration, the damping force adjustment shown in FIG. 3 is adjusted.
Like the hydraulic shock absorber 48 , by adjusting the relief pressure of the relief valves 87, 102 by the current supplied to the proportional solenoids 83, 103, the extension side and contraction side damping forces can be directly controlled regardless of the piston speed. can do.

Also, as in the first embodiment, the spring 12
Volume elasticity is set in the back pressure chambers 79a and 99a by 8 and 134, and the orifices 126 and 132 are provided between the back pressure passages 123 and 134 and the back pressure chambers 79a and 99a.
As a result, a low-pass filter in which the pressure in the back pressure chambers 79a, 99a is a first-order lag system with respect to the relief pressures in the relief valves 87, 102 is formed, so that relief by high frequency input to the piston rod 4 is achieved. Even if pulsation occurs in the oil liquid in the back pressure passages 123, 134 due to surging of the valves 87, 102 or self-excited vibration, the rise in pressure in the back pressure chambers 79a, 99a is gently attenuated. It is possible to prevent an excessive increase in the back pressure of 97 and generate an appropriate damping force.

In the second embodiment, an example in which both the extension side and contraction side damping force adjusting mechanisms 66, 67 are provided is shown, but only one of them is provided for weight reduction and simplification of specifications. It may be provided.

[0085]

As described above in detail, according to the damping force adjusting hydraulic shock absorber of the present invention, the relief pressure of the relief valve is adjusted during the expansion or contraction stroke of the piston rod, and the opening is performed according to this adjustment. Since the pressure in the back pressure chamber of the valve pressure adjustment mechanism changes and the opening degree of the valve body of the damping force adjustment valve is determined according to the pressure in the back pressure chamber and the pressure in the communication passage, damping is performed regardless of the piston speed. The force can be controlled directly. And back pressure
The chamber is bulk elastic by spring means and two orifices
Forms a first-order lag system and forms a low-pass filter.
Relief due to high frequency input to the piston rod
Oil surging in back pressure passage due to valve surging and self-excited vibration
Even if pulsation occurs, the increase in pressure in the back pressure chamber is gently attenuated
To prevent an excessive increase in back pressure
Can cause weakness. Furthermore, from claim 2
In the damping force adjusting type hydraulic shock absorber according to the present invention, the relief pressure of the extension side relief valve increases due to the movement of the proportional solenoid to one side of the plunger, and the movement to the other side causes the movement of the compression side to the contraction side relief valve. Since the relief pressure increases,
Different types of damping force characteristics can be set for the extension side and the contraction side. As a result, the damping force can be controlled directly regardless of the piston speed, so there is no need to detect the piston speed, and the burden on the controller can be reduced.
Further, since it is possible to generate a stable damping force even with respect to a high frequency input to the piston rod, it is possible to prevent deterioration of riding comfort due to a response delay of the damping force adjusting valve.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a damping force adjusting hydraulic shock absorber which is referred to for explaining a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a side surface of an electromagnetic proportional control valve of the device shown in FIG.

FIG. 3 is a vertical cross-sectional view of a side surface of a damping force adjustable hydraulic shock absorber that is referred to in order to explain a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a damping force adjusting hydraulic shock absorber according to the first embodiment of the present invention.

5 is a vertical cross-sectional view of a side surface of an electromagnetic proportional control valve that is another embodiment of the relief valve of the apparatus of FIG.

FIG. 6 is a vertical cross-sectional view of a side surface of a damping force adjusting hydraulic shock absorber according to a second embodiment of the present invention.

FIG. 7 is a diagram showing damping force characteristics with respect to input frequency to the piston rod of the apparatus of FIGS. 4 and 6;

[Explanation of symbols]

1 Damping force adjustable hydraulic shock absorber 2 cylinders 2a Cylinder upper chamber 2b Cylinder lower chamber 3 pistons 4 piston rod 9 passages 12 Extension side communication passage 13 Contraction side communication passage 17,26 Poppet valve (damping force adjustment valve) 20,30 Back pressure chamber (valve opening pressure adjustment mechanism) 23,32 Orifice 25 Relief valve on extension side 34 Relief valve on compression side 37 Proportional solenoid 39,41 Needle (valve) 44,45 Spring member (spring means) 48 Damping force adjustable hydraulic shock absorber 49 cylinders 49a Cylinder upper chamber 49b Cylinder lower chamber 54 piston 55 Piston rod 66 Extension side damping force adjustment mechanism (communication path) 67 Shrinkage side damping force adjustment mechanism (communication path) 77,97 Disc valve (damping force control valve) 79a, 99a Back pressure chamber (valve opening pressure adjustment mechanism) 81,101 Orifice 82,102 Relief valve 83b, 103b Spring member (spring means) 86,106 Needle (Valve) 111,113 Spring member (spring means) 114,116 Relief valve 115,117 Orifice 124,126 Orifice 130,132 Orifice

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-50-153321 (JP, A) JP-A-54-133630 (JP, A) JP-A-62-28581 (JP, A) JP-A-5- 332388 (JP, A) German patent application publication 3924168 (DE, A 1) Japanese Patent Publication No. 42-17786 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) F16F 9/46 B60G 17/08

Claims (2)

(57) [Claims] 1. A cylinder in which an oil liquid is sealed, a piston slidably fitted in the cylinder to define two chambers in the cylinder, one end of which is connected to the piston and the other end of which is the cylinder. A piston rod extended to the outside of
A damping force adjusting valve having a communication passage that communicates one chamber and the other chamber in the cylinder, and a valve body that is provided in the communication passage and that opens by a flow of an oil liquid in one direction to generate a damping force. A back pressure chamber provided on the back side of the damping force adjusting valve,
Branch from the communication passage upstream of the damping force control valve and
A back pressure passage communicating with the pressure chamber, and a back pressure passage arranged in series with the back pressure passage.
Two orifices, the valve body of the damping force control valve and the front
And a spring means provided between the back pressure chamber and the back pressure chamber.
The pressure in the pressure chamber is applied to the valve body via the spring means.
And a valve opening pressure adjusting mechanism for changing the valve opening pressure of the valve body, and a pressure of the back pressure chamber connected between the two orifices of the back pressure passage downstream of the damping force adjusting valve in the communication passage. A damping force adjusting hydraulic shock absorber, comprising: a relief valve for relief adjustment. 2. A cylinder in which an oil liquid is sealed, a piston slidably fitted in the cylinder to define two chambers in the cylinder, one end of which is connected to the piston and the other end of which is the cylinder. A piston rod extended to the outside of
An extension side communication passage that allows the two chambers in the cylinder to communicate with each other and allows the oil liquid to flow during the expansion stroke of the piston rod, and the two chambers in the cylinder that communicate with each other to allow the oil liquid to flow during the compression stroke of the piston rod. An expansion-side damping force adjusting valve having a compression-side communication passage that allows flow, a valve body that opens by the flow of oil liquid in the expansion-side communication passage to generate a damping force, and an oil liquid in the compression-side communication passage Compression side damping force adjusting valve having a valve body that opens by the flow of the above to generate a damping force, and an extension side spine provided on the back side of the extension side damping force adjusting valve.
From the pressure chamber and the extension side communication passage to the extension side damping force adjusting valve
Extension side that branches on the upstream side of and communicates with the extension side back pressure chamber
Back pressure passage and two arranged in series in the extension side back pressure passage
Expansion side orifice and valve element of the expansion side damping force adjusting valve
Between the extension side back pressure chamber and the extension side spring means
And the pressure in the extension side back pressure chamber is adjusted to the extension side spring hand.
Change the valve opening pressure of the valve body by acting on the valve body through a step
Extension side opening pressure adjustment mechanism and compression side spine provided on the back side of the compression side damping force adjustment valve
From the compression chamber and the compression-side communication passage to the compression-side damping force adjusting valve
Contraction side that branches at the upstream side of and communicates with the compression side back pressure chamber
A back pressure passage and two compressed back pressure passages arranged in series
A contraction side orifice and a valve body of the contraction side damping force adjusting valve
The contraction side spring means provided between the contraction side back pressure chamber and
Having the pressure of the compression-side back pressure chamber by the compression-side spring means.
To act on the valve body via the valve to change the valve opening pressure of the valve body.
And a compression side valve opening pressure adjusting mechanism, which is connected between the two expansion side orifices and relieves the pressure of the expansion side back pressure chamber to a downstream side of the expansion side damping force control valve in the expansion side communication passage. The pressure in the compression-side back pressure chamber is connected between the expansion-side relief valve to be adjusted and the two compression-side orifices, and is adjusted by relieving the pressure in the compression-side communication passage downstream of the compression-side damping force control valve. The contraction side relief valve and the valve body of the extension side relief valve are biased in the valve closing direction by moving to one side, and the valve body of the compression side relief valve is biased in the valve closing direction by moving to the other side. A damping force adjusting hydraulic shock absorber, comprising: a proportional solenoid having a plunger.