JPH06330977A - Damping force regulation type hydraulic buffer - Google Patents

Abstract

PURPOSE:To set damping forces on the expansion side and on the contraction to values different from each other and to perform direct control of a damping force despite of the speed of a piston. CONSTITUTION:A piston 3 to which a piston rod 4 is coupled is fitted in a cylinder 2. A cylinder upper chamber 2a and a cylinder lower chamber 2b are intercommunicated through a communicating passage 9 having check valves 10 and 11. A poppet valve 15 is arranged in a communicating passage 12 on the expansion side bypassing the check valve 10 and a poppet valve 24 is located in a passage 13 on the contraction side running around the check valve 11. A portion situated upper stream from the poppet valve 15 and a back pressure chamber 18 are intercommunicated through a back pressure passage 20 and a relief valve 22 is provided. A portion situated upper stream from the poppet valve 24 is communicated with a back pressure chamber 18 through a back pressure passage 29, and a relief valve 31 is arranged. On the expansion side, the poppet valve 15 is opened at an opening responding to the pressures of the cylinder upper chamber 2a and the back pressure chamber 18 and on the contraction side, the poppet valve 24 is opened at an opening responding to the pressures of the cylinder lower chamber 2b and the back pressure chamber 27 to generate a damping force. Through regulation of the relief pressures of the relief valves 22 and 31, the damping forces on the elongation side and the contraction side are directly controllable.

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. Is connected to the main oil liquid passage and the bypass passage, and a damping force generating mechanism (orifice, disk valve, etc.) for generating a large damping force is provided in the main oil liquid passage,
In the bypass passage, a damping force generating mechanism having a small damping force and a damping force adjusting valve for opening and closing the bypass passage are 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 accompanying the expansion and contraction of the piston rod, and a small damping force is applied to both the expansion side and the contraction 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 It changes according to the magnitude of the piston speed. Therefore, the conventional damping force adjustment is to adjust the damping coefficient with the piston speed as a variable,
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 so that the desired damping force is generated with respect to the input of the piston speed. Calculate the damping coefficient,
Further, it is necessary to take a procedure of driving the actuator so that the damping force adjusting valve has an opening degree 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.

The present invention has been made in view of the above points, and an object thereof is to provide a damping force adjustable hydraulic shock absorber capable of directly controlling the damping force regardless of the piston speed.

[0010]

In order to solve the above-mentioned problems, a damping force adjustable hydraulic shock absorber of the present invention is provided with a cylinder in which an oil liquid is sealed and a slidable fitting member. A piston that defines the inside of the cylinder into two chambers, a piston rod that has one end connected to the piston and the other end that extends to the outside of the cylinder, and a damping force that communicates between the two chambers and generates a damping force. In a hydraulic shock absorber having a generating mechanism, a communication passage that communicates one chamber and the other chamber in the cylinder, and a valve that is provided in the communication passage and that opens by a unidirectional flow to generate a damping force. A valve body, a back pressure chamber communicating with the upstream side of the valve body through an orifice, and a valve opening pressure adjusting mechanism for changing the valve opening pressure of the valve body according to the pressure of the back pressure chamber; The pressure of the back pressure chamber can be adjusted by connecting the pressure chamber and the downstream side of the valve body. Characterized in that it includes a that relief valve.

[0011]

With this construction, the relief pressure of the relief valve is adjusted during the expansion or contraction stroke of the piston rod, and the pressure in the back pressure chamber changes in accordance with this adjustment.
Since the opening degree of the valve element is determined according to the pressure in the back pressure chamber and the pressure in the communication passage, it is possible to directly control the opening regardless of the piston speed.

[0012]

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

The first embodiment will be described with reference to FIG. As shown in FIG. 1, the damping force adjustable hydraulic shock absorber 1 is
A piston 3 is slidably fitted in a cylinder 2 in which oil liquid is sealed.
The inside is divided into two chambers, a cylinder upper chamber 2a and a cylinder lower chamber 2b. One end of a piston rod 4 is connected to the piston 3, and the other end of the piston rod 4 is connected to the cylinder 2
It is inserted into a rod guide and a seal member (not shown) provided at the end of the cylinder 2 and extends to the outside of the cylinder 2.

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. A reservoir 14 (accumulator) is connected to the communication passage 9 for compensating the volume change in the cylinder 2 due to the expansion and contraction of the piston rod 4 by compressing and expanding gas.

The extension side communication passage 12 is provided with a poppet valve 15 for adjusting the passage area. Poppet valve 15
A poppet 17, which is a valve body, is slidably fitted in the guide 16, and the passage area of the extension side passage 12 is adjusted by the movement of the poppet 17. The poppet 17 is adapted to move in the valve opening direction by receiving pressure on the upstream side (the cylinder upper chamber 2a side) in the extension side communication passage 12. Further, a back pressure chamber 18 is provided on the back side of the poppet 12 in the guide 16, and the pressure in the back pressure chamber 18 acts in a direction to close the poppet 17, thereby providing a valve opening pressure adjusting mechanism. Is formed. Further, in the back pressure chamber 18, a spring 19 that biases the poppet 17 in the valve closing direction is provided.

A back pressure passage 20 is provided for connecting the back pressure chamber 18 to the upstream side of the poppet valve 15 in the extension side passage 12 (the cylinder upper chamber 2a side). The back pressure passage 20 has an orifice
21 and a relief valve 22 are provided. Relief valve 22
, The relief pressure can be set arbitrarily,
The relief oil 23 is made to flow to the downstream side (the reservoir 14 side) of the poppet valve 15 in the extension side communication passage 12 by the relief passage 23. Further, the orifice 21 reduces the pressure of the oil liquid flowing to the back pressure passage 20 so that the relief valve 22 is less burdened.

Similarly, the contraction side communication passage 13 is provided with a poppet valve 24 for adjusting the passage area. In the poppet valve 24, a poppet 26, which is a valve body, is slidably fitted in a guide 25, and the passage area of the contraction side passage 13 is adjusted by the movement of the poppet 26. Poppet
26 receives the pressure on the upstream side (the cylinder lower chamber 2b side) of the compression side communication passage 13 and moves in the valve opening direction. In addition, a back pressure chamber 27 is provided on the back side of the poppet 26 in the guide 25, and the pressure in the back pressure chamber 27 acts in the direction to close the poppet 26, whereby a valve opening pressure adjusting mechanism. Is formed. Further, in the back pressure chamber 27, a spring 28 that biases the poppet 26 in the valve closing direction is provided.

A back pressure passage 29 is provided for connecting the back pressure chamber 27 to the upstream side of the poppet valve 24 (the cylinder upper chamber 2a side) of the contraction side communication passage 13. An orifice 30 and a relief valve 31 are provided in the back pressure passage 29. Relief valve
Reference numeral 31 allows the relief pressure to be set arbitrarily, and the relief oil 32 is made to flow to the downstream side (reservoir 14 side) of the poppet valve 24 in the compression side passage 13 by the relief passage 32. Further, the orifice 30 reduces the pressure of the oil liquid flowing to the back pressure passage 29 so that the burden on the relief valve 31 is reduced.

The operation of the first embodiment constructed as above 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 15 by flowing the flow.

In the poppet valve 15, the pressure on the cylinder upper chamber 2a side acts to move the poppet 17 in the valve opening direction. On the other hand, the pressure on the cylinder upper chamber 2a side acts on the back pressure chamber 18 via the back pressure passage 20 to move the poppet 17 in the valve closing direction. When the pressure in the back pressure chamber 18 exceeds the set pressure of the relief valve 22, the relief valve 22 opens and the oil liquid in the back pressure passage 20 flows through the relief passage 23 to the cylinder lower chamber 2b side.
The pressure in the back pressure chamber 18 can be arbitrarily set by the relief valve 22. Then, the poppet 17 is the cylinder upper chamber 2a.
It moves to a position where the side pressure, the set pressure of the relief valve 22 and the biasing force of the spring 19 are balanced. Therefore, the poppet valve 15 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 cylinder upper chamber
The passage area of the poppet valve 15 changes according to the pressure of 2a, and a predetermined damping force is generated regardless of the piston speed.

When the pressure in the cylinder upper chamber 2a exceeds a predetermined value, the pressure regulating valve 7 of the piston 3 opens and the oil liquid in the cylinder upper chamber 2a passes directly through the extension side passage 5 and directly into the cylinder lower chamber 2b. A damping force is generated by flowing to.

During the contraction 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 24 by flowing through 13.

In the poppet valve 24, the poppet 26 is moved to a position where the pressure on the cylinder lower chamber 2b side, the set pressure of the relief valve 31 and the spring 28 are balanced, and the cylinder bottom The damping force is determined by opening the valve at an opening degree according to the pressure in the chamber 2b. In this way, the passage area of the poppet valve 24 changes according to the pressure in the cylinder lower chamber 2b, and a predetermined damping force is generated regardless of the piston speed.

When the pressure in the lower cylinder chamber 2b exceeds a predetermined value, the pressure regulating valve 8 of the piston 3 opens and the oil liquid in the lower cylinder chamber 2b passes directly through the contraction side passage 6 to the upper cylinder chamber 2a. A damping force is generated by flowing to.

In this way, by adjusting the relief pressure of the relief valves 22 and 31, the extension side and the contraction side damping forces can be directly controlled regardless of the piston speed.

Next, an embodiment in which the electromagnetic proportional control valve 33 shown in FIG. 2 is used in place of the relief valves 22 and 31 in the damping force adjusting hydraulic shock absorber 1 shown in FIG. 1 will be described.

As shown in FIG. 2, an electromagnetic proportional control valve 33
Is a relief valve 35 for relieving the back pressure passage 34 connected to the poppet valve 15 and a back pressure passage connected to the poppet valve 24.
The relief valve 37 that relieves the relief valve 36 and the proportional solenoid 38 that opens and closes the relief valves 35 and 37 are roughly configured.

The relief valve 35 includes the back pressure passage 36 and the relief chamber.
39 is a needle valve that opens and closes with a needle 40,
Similarly, the relief valve 37 is a needle valve that opens and closes the back pressure passage 36 and the relief chamber 41 with the needle 42. The needles 40 and 42 are provided at both ends of a rod 44 connected to the plunger 43 of the proportional solenoid 38, and when the rod 44 is moved to close one of the relief valves 35 and 37, the other is opened. Has become.

The proportional solenoid 38 is provided with a spring 45 for urging the rod 44 toward the relief valve 37, and normally the relief valve 37 is closed and the relief valve 35 is opened. The proportional solenoid 38 generates a force in the direction of moving the rod 44 toward the relief valve 35 side against the biasing force of the spring 45 via the plunger 43 according to the energized current. And
It is possible to adjust the relief pressure of the relief valve 37 by adjusting the relief pressure of the relief valve 37 according to the energization current and further increasing the energization current to move the rod 44 to the relief valve 35 side.

The relief chamber 39 and the relief chamber 41 are communicated with each other via a passage 46 in the proportional solenoid 38, and further connected to the reservoir 14 side via a relief passage 47 provided in the relief valve 37. There is.

Electromagnetic proportional control valve 33 configured as described above
The action of will be described below.

The proportional solenoid 38 is energized and the relief valve 37
By adjusting the relief pressure of, the opening degree of the poppet valve 24 is adjusted, and the damping force on the compression side can be controlled. At this time, since the relief valve 35 is in the open state, the opening degree of the poppet valve 15 increases and the damping force on the extension side decreases. Therefore, the damping force characteristic is as shown by in FIG. In addition, in the figure, a case is shown in which the current I supplied to the proportional solenoid 38 is minimized so that the damping force on the contraction side is maximized.

Further, the current flowing to the proportional solenoid 38 is increased to move the rod 44 to the relief valve 35 side and the relief pressure of the relief valve 35 is adjusted, whereby the opening degree of the poppet valve 15 is adjusted and expanded. The damping force on the side can be controlled. At this time, since the relief valve 37 is in an open state, the opening degree of the poppet valve 24 increases and the compression force on the compression side decreases. Therefore, the damping force characteristic is as shown by in FIG. In the figure, the case is shown in which the energization current I to the proportional solenoid 38 is maximized so that the damping force on the extension side is maximized.

In this way, by adjusting the current supplied to the proportional solenoid 38, the damping force characteristic can be continuously adjusted between and in FIG. In addition, 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.

By using two electromagnetic proportional control valves as the relief valves 22 and 31 of the embodiment shown in FIG. 1, the respective energizing currents are adjusted to independently control the damping force on the extension side and the compression side. You can also do it.

Next, a second embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 3, the damping force adjusting type hydraulic shock absorber 48 has a triple cylinder 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 expansion-side passage 60 and a compression-side passage 61 that 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 77 is provided as a valve element that allows only the flow of oil liquid from the cylinder upper chamber 49a side of the valve passage 71 to the valve chamber 68a side to generate a damping force. It is provided. In the guide hole 72,
The small diameter part on the tip side of the plunger 78 is slidably fitted,
The large diameter portion of the plunger 78 on the base end side is slidably fitted in a guide hole 79 provided in the plug 69.
A back pressure chamber 79a is formed inside 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. And
The orifice 81 reduces the pressure of the oil liquid flowing into the back pressure passage 80 so that the relief valve 82, which will be described later, is less burdened.

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 to open and close the communication passage 85 for communicating between the relief chamber 84 formed in the plug 69 and the back pressure chamber 79a by the needle 86 connected to the proportional solenoid 83. It is a needle valve. The proportional solenoid 83 is configured to urge the needle 86 in the valve closing direction with a force according to the energizing current to adjust the relief pressure of the relief valve 82. The relief chamber 84 is connected to the valve chamber 68a by a relief passage 87.

A pressing member 88, which abuts on the back side of the disc valve 77, is connected to the plunger 78, and the disc valve 77 receives pressure from the back pressure chamber 79a.
77 is pressed in the valve closing direction, and this pressing forms a valve opening pressure adjusting mechanism for adjusting the valve opening pressure of the disc valve 77.

The compression side damping force adjusting mechanism 67 has a bottom portion 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 97 is provided as a valve body that allows only the oil liquid to flow from the cylinder lower chamber 49b side of the valve passage 93 to the valve chamber 89a side to generate a damping force. It is provided. In the guide hole 94,
The small diameter part on the tip side of the plunger 98 is slidably fitted,
The large diameter portion of the plunger 98 on the base end side is slidably fitted in a guide hole 99 provided in the plug 90.
A back pressure chamber 99a is formed inside 99. A back pressure passage 100 is penetrated through the plunger 98 along its axis,
An orifice 101 is provided in the back pressure passage 100. Then, the orifice 101 reduces the pressure of the oil liquid flowing to the back pressure passage 100 so that the load on the relief valve 102 described later is reduced.

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 that opens and closes by a needle 106 connected to. The proportional solenoid 103 adjusts the relief pressure of the relief valve 102 by urging the needle 106 in the valve closing direction with a force according to the applied current. Relief room 10
The relief passage 107 communicates with the valve chamber 89a.

The plunger 98 is connected with a pressing member 108 that abuts against the back side of the disc valve 97, and the plunger 98 presses the disc valve 97 in the closing direction by the pressure received from the back pressure chamber 99a. Thus, a valve opening pressure adjusting mechanism for adjusting the valve opening pressure of the disc valve 97 by this pressing is formed.

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

During the extension stroke of the piston rod 55, the piston 54 slides so that the oil liquid on the cylinder upper chamber 49a side passes through the passage.
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 adjusting the urging force of the needle 86 by setting the relief pressure of the relief valve 82 by the current supplied to the proportional solenoid 83, and the disc pressure can be controlled according to the pressure in the cylinder upper chamber 49a. The opening degree of the valve 77 changes 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 to the cylinder lower chamber 49b. A damping force is generated by flowing to.

During the compression stroke of the piston rod 55, the sliding of the piston 54 causes 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 by 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 adjusting the urging force of the needle 106 by setting the relief pressure of the relief valve 102 by the current supplied to the valve 3, and the disc valve 97 can be opened depending on the pressure of the cylinder lower chamber 49b. The degree changes and a predetermined damping force is generated regardless of the piston speed.

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

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

Next, the control of the vehicle suspension control system to which the damping force adjusting hydraulic shock absorber 48 of the second embodiment is applied will be described with reference to FIGS. 5 to 7. In addition,
The basic theory of control described below is the same as the content shown in Japanese Patent Application No. 5-2148 filed by the present applicant.

As shown in FIG. 5, the acceleration signal A from the acceleration sensor for measuring the vertical acceleration provided on the vehicle body of the automobile is integrated in a block to calculate the vertical velocity V of the vehicle, and the block is calculated. And this speed V gain K
The target damping force F is calculated by multiplying by. Here, the target damping force F has a positive value when the vehicle body is moving upward, and a negative value when the vehicle body is moving downward. Then, the block calculates the energizing current I ₁ to the expansion side proportional solenoid 83 corresponding to the target damping force F, and the block energizes the contracting side proportional solenoid 103 corresponding to the target damping force F to the contracting side.
Calculate I ₂ . At this time, the block calculates the current I ₁ according to the target damping force F when the target damping force F is positive, and sets the current I ₁ = 0 when the target damping force F is negative. In the block, the current I ₂ corresponding to the target damping force F is calculated when the target damping force F is negative, and the current I ₂ = 0 is set when the target damping force F is positive.

In this way, the target damping force F is generated by one of the expansion side damping force adjusting mechanism 66 and the contraction side damping force adjusting mechanism 67 of the damping force adjusting hydraulic shock absorber 48 according to the vertical speed of the vehicle body. By making the other damping force smaller, it is possible to effectively suppress the vibration of the vehicle body based on the basic theory.

Further, as shown in FIG. 6, in addition to that shown in FIG. 5, the block performs a fast Fourier transform on the acceleration signal A to calculate the level value E of the spectrum in a predetermined frequency region, and the block A damping force correction value Z is calculated by multiplying the level value E by a function having a dead zone, and the damping force correction value Z is output by a current I ₁ ,
Add to I ₂ .

Here, the unsprung resonance point (10 to 10) of the automobile is set to the predetermined frequency region of the spectrum calculated by the block.
By setting it to about 15 Hz), it is possible to judge the road surface condition such as a bad road that causes the deterioration of the ground contact of the wheels and the full stroke of the suspension device based on the level value E. By appropriately increasing or decreasing the damping force on both the extension side and the contraction side of the damping force adjusting hydraulic shock absorber 48 according to the road surface condition, it is possible to eliminate the insufficient unsprung damping.

Next, the control of the suspension control device when a failure occurs will be described with reference to FIG. Figure 7
As shown in FIG. 5, in addition to the one shown in FIG. 5 or 6 (only the one for FIG. 5 is shown in FIG. 7), an abnormality of each sensor of the suspension control device (only the acceleration is shown in FIG. 7) is shown by a block. The control gain K of the block is set to 0 for the signal, and further, the damping force adjusting hydraulic shock absorber 48 generates a damping force capable of sufficiently ensuring the steering stability of the vehicle on both the extension side and the contraction side.
Outputs currents I ₁ and I ₂ to 83 and 103.

Thus, even when a failure occurs, by supplying the predetermined energizing currents I ₁ and I ₂ to the proportional solenoids 83 and 103, sufficient damping force can be obtained on both the extension side and the contraction side. It does not impair steering stability.

In the control of this embodiment, the energizing current I ₁ ,
When I ₂ = 0, the damping force of the damping force adjustment type hydraulic shock absorber 48 is minimum, but proportional to the needles 86 and 106 of the relief valves 82 and 102 by applying an initial load in the valve closing direction with a spring or the like. A predetermined damping force is generated when the energizing currents I ₁ and I ₂ to the solenoids 83 and 103 are set to 0, so that the control gain K of the block is set to 0 when a failure occurs, and a predetermined relief is provided by a spring. Pressure can be obtained and sufficient damping force can be obtained. In such a case, in the normal control, when a smaller damping force than that at the time of failure is required, the directions of the energizing currents I ₁ and I ₂ are reversed and the proportional solenoid 83,
The needles 86 and 106 may be biased in the valve opening direction by 103.

Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is the same as the damping force adjusting hydraulic shock absorber 48 shown in FIG. 3 except that the extension side damping force adjusting mechanism 67 and the contraction side damping force adjusting mechanism 68 are different. The same members as those of the embodiment are designated by the same reference numerals and only different portions will be described in detail.

As shown in FIG. 8, an inlet passage 112 (described later) communicates with the cylinder upper chamber 49a side and an outlet passage 113 (described later) communicates with the cylinder lower chamber 49b side on the side surface of the passage member 64. An extension-side damping force adjusting mechanism 109 that constitutes an extension-side communication passage is provided. A compression-side damping force adjusting mechanism (not shown) is provided on the opposite side surface of the passage member 64 to form a compression-side communication passage when the cylinder upper chamber 49a and the cylinder lower chamber 49b are communicated with each other. However, this contraction-side damping force adjusting mechanism is not limited to the extension-side damping force adjusting mechanism except that the inlet passage communicates with the cylinder lower chamber 49b side and the outlet passage communicates with the cylinder upper chamber 49a side. Since it has the same structure as 109, only the extension side damping force adjusting mechanism will be described in detail below.

In the damping force adjusting mechanism 109, the bottom of a cylindrical valve case 110 having a bottom is coupled to the side wall of the passage member 64, and the proportional solenoid 111 is provided in the opening of the valve case 110.
The cylindrical fitting portion 111a is fitted and screwed to form the valve chamber 110a in the valve case 110. At the bottom of the valve case 110, there are provided an inlet passage 112 and an outlet passage 113 for communicating the valve chamber 110a with the passage 70 and the passage 74 of the passage member 64, respectively.

An annular valve seat 114 is formed inside the bottom of the valve case 110.
An annular disc valve 115 is seated at 4 as a valve element that allows only the flow of oil liquid from the inlet passage 112 side to the valve chamber 110a side to generate a damping force and prevents the flow in the opposite direction. There is. The disc valve 115 is formed by laminating a plurality of discs, and the outer periphery of the disc valve 115 is supported and positioned by a disc guide 116.

In the fitting portion 111a of the proportional solenoid 111,
A substantially cylindrical guide member 117 having a guide hole 117a is fitted therein, and a bottomed cylindrical plunger 118 forming a valve opening pressure adjusting mechanism is slidably fitted in the guide hole 117a. . The bottom of the plunger 118 is in contact with the inner peripheral edge of the disc valve 115. A valve seat member 119 is attached to the opening of the guide hole 117a, and a back pressure chamber 120 is formed by the valve seat member 119 on the back side of the plunger 118 in the guide hole 117a. A relief chamber 121 is formed by the guide member 117 and the valve seat member 119, and the guide member 117 is provided with a relief passage 122 that allows the valve chamber 110a and the relief chamber 121 to communicate with each other. At the bottom of the plunger 118, an orifice 123 is provided as a back pressure passage that connects the inlet passage 112 and the back pressure chamber 120.
Then, the pressure of the oil liquid to the back pressure chamber 120 is reduced by the orifice 123 so that the load on the relief valve described later is reduced. Plunger 118 and valve seat member 119
A spring 124 for urging the plunger 118 toward the disc valve 115 is interposed between them.

The valve seat member 119 is provided with a valve hole 125 which connects the back pressure chamber 120 and the relief chamber 121 to each other.
The tip of a needle 126 connected to an actuating rod (not shown) of the proportional solenoid 111 is inserted into 125. The valve hole 125 and the needle 126 constitute a relief valve 127 that relieves the pressure in the back pressure chamber 120, and the proportional solenoid 111 urges the needle 126 in the valve closing direction with a force according to the energizing current. To adjust the relief pressure.

The operation of the present embodiment configured as described above will be described below.

Similarly to the second embodiment, during the extension stroke of the piston rod 55, the oil liquid on the cylinder upper chamber 49a side flows into the inlet passage 112 of the damping force adjusting mechanism 109 through the passage 70. The oil liquid flowing from the inlet passage 112 opens the disc valve 116, flows into the valve chamber 110a, passes through the outlet passage 113,
Flows to the cylinder lower chamber 49b side through the passage 74. And
The disc valve 116 is driven by the pressure on the cylinder upper chamber 49a side.
The flexure causes a gap to form with the valve seat 114, and a damping force is generated according to the passage area of this gap. At this time, since the disc valve 116 is pressed against the valve seat 114 by the plunger 118, the valve opening pressure is adjusted by this pressing load, and a damping force proportional to the pressing load is generated.

The pressing load of the plunger 118 is such that the pressure of the oil liquid on the cylinder upper chamber 49a side is the orifice 12 of the plunger 118.
3 is transmitted to the back pressure chamber 120 and is generated by the pressure of the oil liquid in the back pressure chamber 120 and the elastic force of the spring 124. At this time, when the pressure in the back pressure chamber 120 exceeds the set pressure of the relief valve 127, the relief valve 127 opens and the oil liquid in the back pressure chamber 120 is relieved to the relief chamber 121 and passes through the relief passage 122 to the valve chamber 110a. Since it flows, the pressure in the back pressure chamber 120 can be arbitrarily set by the relief valve 127. Therefore, the current applied to the proportional solenoid 111 causes the needle 12
The damping force can be directly controlled by adjusting the biasing force of 6 and setting the relief pressure of the relief valve 127.
The opening of the disc valve 115 changes according to the pressure in the cylinder upper chamber 49a, and a predetermined damping force is generated regardless of the piston speed.

Further, since the plunger 118 is constantly pressed against the disc valve 115 by the elastic force of the spring 124, the rattling of the plunger 118 and the disc valve 115 can be prevented. Even if it does not operate, a predetermined minimum damping force can be secured.

The disc valve 115, as shown in FIG.
By using a stack of a plurality of disks, an appropriate damping force can be applied to the flexure due to the friction between the disks, and the disk valve 115 can be prevented from oscillating.

On the other hand, during the compression stroke of the piston rod 55, the disc valve 115 and the relief valve 127 are closed by the pressure of the oil liquid on the cylinder lower chamber 49b side, so that the oil liquid does not flow through the damping force adjusting mechanism 109 and the cylinder The oil liquid on the lower chamber 49b side passes through the damping force adjusting mechanism on the contraction side, and the cylinder upper chamber
By flowing to the side of 49a, a predetermined damping force is generated in the same manner as above regardless of the piston speed.

Therefore, similarly to the second embodiment, the proportional solenoid 111 of the extension side damping force adjusting mechanism 109 is used.
By adjusting the relief pressure according to the current supplied to the proportional solenoid of the contraction-side damping force adjusting mechanism, the extension-side and contraction-side damping forces can be directly controlled regardless of the piston speed.

[0080]

According to the damping force adjusting type 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 pressure in the back pressure chamber changes in accordance with this adjustment. Thus, since the opening degree of the valve element is determined according to the pressure of the back pressure chamber and the pressure of the communication passage, direct control can be performed regardless of the piston speed. As a result, when applied to the suspension control device, the damping force can be directly controlled regardless of the piston speed, so that it is not necessary to detect the piston speed, and the load on the controller can be reduced, which is an excellent effect.

[Brief description of drawings]

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

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

FIG. 3 is a front vertical sectional view of a damping force adjusting hydraulic shock absorber according to a second embodiment of the present invention.

FIG. 4 is a diagram showing damping force characteristics when the apparatus of FIG. 1 is combined with the electromagnetic proportional control valve of FIG.

5 is a block diagram showing an example of control by a controller of a suspension control device to which the damping force adjusting hydraulic shock absorber of FIG. 3 is applied.

6 is a block diagram showing another example of control by the controller of the suspension control device to which the damping force adjusting hydraulic shock absorber of FIG. 3 is applied.

7 is a block diagram showing an example of control when a failure occurs in the control by the controller of FIG.

FIG. 8 is a vertical sectional view of a damping force adjusting mechanism of a damping force adjusting hydraulic shock absorber according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Damping force adjustable hydraulic shock absorber 2 Cylinder 2a Cylinder upper chamber 2b Cylinder lower chamber 3 Piston 4 Piston rod 12 Extension side communication passage 13 Compression side communication passage 17,26 Poppet (valve body) 18,27 Back pressure chamber 20,29 Back pressure passage 22,31 Relief valve 48 Damping force adjusting hydraulic shock absorber 49 Cylinder 49a Cylinder upper chamber 49b Cylinder lower chamber 54 Piston 55 Piston rod 66 Extension side damping force adjusting mechanism (communicating passage) 67 Compression side damping force adjusting mechanism ( 77,97 Disc valve (valve) 79a, 99a Back pressure chamber 80,100 Back pressure passage 82,102 Relief valve 109 Damping force adjustment mechanism (communicating passage) 115 Disc valve (valve) 120 Back pressure chamber 123 Orifice 127 Relief valve

Claims (1)

[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
In a hydraulic shock absorber having a damping force generation mechanism that communicates between the two chambers and generates a damping force, a communication passage that communicates one chamber and the other chamber in the cylinder, and a communication passage that is provided in the communication passage, A valve body that opens by a flow in one direction to generate a damping force, and a back pressure chamber that communicates with the upstream side of the valve body via an orifice. The valve body opens according to the pressure of the back pressure chamber. A valve opening pressure adjusting mechanism for changing the valve pressure, and a relief valve for communicating the back pressure chamber and the downstream side of the valve body and adjusting the pressure of the back pressure chamber are provided. Damping force adjustable hydraulic shock absorber.