JP2000120755A - Damping force variable control type buffer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve responsiveness, simplify a structure, lower a cost, and certainly avoid operational failure caused by biting of refuse. SOLUTION: In this damping force variable control type buffer, a back pressure chamber A communicated with an extension side oil chamber, a pilot valve 6 opening/closing a pilot passage 26a communicating the back pressure chamber A with a reservoir 70c and control means variably controlling pilot passage 26a closing force by the pilot valve 6 are equipped. A main valve 18 is so formed that an introducing hole 19a communicating the extension side oil chamber with the back pressure chamber A is formed in a base plate 19 forming the back pressure chamber A together with the pilot valve 6 and a plate valve laminated body 20 formed by laminating a plurality of plate valves 20a made of a plate spring and having different diameter is arranged on the back pressure chamber A side of the base plate 19 so as to open and close the introducing hole 19a, and the channel resistance of a communicating passage 72 is variably controlled by the spring force of the plate valve laminated body 20 and back pressure in the back pressure chamber A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable damping force control type hydraulic shock absorber in which a damping force is variably controlled according to running conditions and the like.

[0002]

2. Description of the Related Art In recent years, automobiles and motorcycles sometimes employ a variable damping force control type hydraulic shock absorber that freely controls a damping force according to road surface conditions, running conditions and the like. As this type of shock absorber, as shown in FIG. 5, there is a so-called recirculation type in which hydraulic oil flows in the same direction in both the extension stroke and the compression stroke. This type of hydraulic shock absorber 10
0 is a cylinder 102 and an outer cylinder 103 defined by a piston 101 into a growth side oil chamber 101a and a compression side oil chamber 101b.
A storage chamber 105 for storing hydraulic oil in an amount equal to or more than the volume of the piston rod 104 is provided between the expansion oil chamber 101a and the storage chamber 105 through a communication path 106. The configuration is such that a control valve 107 for variably controlling the flow path resistance of the hydraulic oil is provided at 106.

As a specific structure of the control valve, the present applicant has proposed a structure in which a desired back pressure is applied to a main valve that opens and closes the communication passage (for example, Japanese Patent Application No. Hei 8 (1996) -108).
-334181). The main valve is configured to open and close a valve hole that forms a part of the communication path with a cylindrical valve body that is disposed to be able to advance and retreat, and the main valve is provided in a back pressure chamber formed on a back side of the valve body. The pressure in the communication passage is introduced, and a pilot passage communicating the back pressure chamber and the storage chamber is opened and closed by a pilot valve.

[0004]

However, in the case of the control valve according to the above proposal, the valve element of the main valve that slides forward and backward is made cylindrical, and a return spring is housed in a limited space in the cylinder. Therefore, a spring having a large spring constant cannot be used, and the responsiveness of the main valve is not sufficient. In addition, the structure is complicated and expensive,
Further, there is a possibility that dust or the like may bite into the sliding portion, and it is considered that improvement in these points is necessary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional circumstances, and can improve responsiveness, has a simple structure and is inexpensive, and reliably avoids the problem of malfunction due to biting of dust or the like. It is an object of the present invention to provide a variable damping force control type shock absorber that can be used.

[0006]

According to the first aspect of the present invention, there is provided a main valve which opens and closes a communication passage for communicating between an extension oil chamber defined by a piston in a cylinder and a storage chamber for storing excess hydraulic oil. ,
A back pressure chamber formed on the back side of the main valve and communicating with the extension oil chamber; a pilot valve for opening and closing a pilot passage communicating the back pressure chamber and the storage chamber; and closing a pilot passage by the pilot valve. In the damping force variable control type shock absorber provided with control means for variably controlling the force, the main valve, the pilot valve and the base plate forming a back pressure chamber, the extension side oil chamber and the back pressure chamber, An introduction hole communicating with the plate valve is formed by stacking a plurality of leaf valves made of leaf springs having different diameters on the back pressure chamber side of the base plate, and the introduction hole is opened and closed. The flow path resistance of the communication passage is variably controlled by the spring force of the plate valve laminate and the back pressure in the back pressure chamber.

According to a second aspect of the present invention, in the first aspect, an annular seal ring made of an elastic body is disposed so as to abut on an outer peripheral edge of the back surface of the plate valve, and the elastic force of the seal ring makes the plate seal. It is characterized by applying an initial load to the valve.

[0008]

According to the first aspect of the present invention, the main valve is
Since the laminated body of a plurality of leaf valves made of leaf springs and having different diameters is arranged on the back pressure chamber side of the base plate and the introduction hole can be opened and closed, the spring constant of the leaf valve laminated body can be easily set. Because it can be made larger, the response to changes in hydraulic pressure can be improved, and the main valve is constructed simply by laminating flat and easy-to-machine plate valves.The structure is simple, cost can be reduced, and sliding parts can be reduced. Because of the absence, it is possible to avoid the problem of malfunction due to dust being caught.

According to the second aspect of the present invention, since the seal ring made of an elastic member is brought into contact with the outer peripheral edge of the rear surface of the plate valve, an initial load corresponding to the spring constant (elastic force) of the seal ring is applied to the plate valve. And it is easy and reliable to set the damping force in the area where the piston speed is low (rise area).
Desired attenuation characteristics can be obtained.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIGS. 1 to 4 are views for explaining a damping force variable control type shock absorber according to an embodiment of the present invention. FIG. 1 is a schematic diagram of a suspension device in which the shock absorber of the embodiment is adopted. 2 is a schematic cross-sectional view of the shock absorber, FIG.
FIG. 4 is a sectional side view and a sectional plan view of a control valve portion of the shock absorber.

In FIG. 1, reference numeral 1 denotes a shock absorber 12 of the present embodiment.
Reference numeral 0 denotes a suspension device, and the suspension device 1 pivotally supports a suspension arm 3 on which wheels 2 are pivotally supported by a vehicle body 4 so as to be vertically swingable, and a coil is provided between the suspension arm 3 and the vehicle body. It is configured with a spring 5 and a shock absorber 120 interposed.

The shock absorber 120 has an extension-side oil chamber 70a in which the hydraulic pressure increases during the extension stroke of the cylinder 70 whose lower end is connected to the suspension arm 3 by the piston 90.
And a pressure side oil chamber 70b in which the hydraulic pressure increases during the compression stroke. The upper end of the piston rod 10 connected to the piston 90 is connected to the vehicle body 4. The piston 90 is provided with a one-way valve 90a that allows only the flow of hydraulic oil from the compression-side oil chamber 70b to the expansion-side oil chamber 70a and blocks the flow in the opposite direction.

The suspension device 1 includes a damping force control valve 110 for variably controlling a damping force generated by the relative movement of the piston 90, a relative moving speed and position of the piston 90 with respect to the cylinder 70, a running speed of the vehicle, Various sensors 11 for detecting data indicating running conditions such as steering angle and acceleration / deceleration, and the control valve 1 according to the running conditions.
There is provided a control device (controller) 12 for controlling 10 based on a preset attenuation characteristic pattern. The damping force characteristic may be input to the control device 12 by a user using a manual switch or the like as appropriate. Reference numeral 13 denotes an electric wiring connecting the control device 12 and the control valve 110.

An outer cylinder 71 is mounted on the outer periphery of the cylinder 70 so as to surround it. The upper ends of the cylinder 70 and the outer cylinder 71 are closed by a rod guide 71a, and the lower ends are closed by a base plate 71b. The space formed by the outer cylinder 71 and the cylinder 70 serves as a storage chamber 70c for storing hydraulic oil of an amount equal to or greater than the volume of the piston rod 10 that has entered the cylinder. The storage chamber 70c is filled with a gas having a predetermined pressure.

As shown in FIG. 2, the base plate 71b is provided with a supply passage 63 for communicating the pressure side oil chamber 70b with the storage chamber 70c.
A check valve 64 that allows only the flow of hydraulic oil from 0c to the pressure side oil chamber 70b is provided.

A guide pipe (communication passage) 72 is inserted between the cylinder 70 and the outer cylinder 71 in the axial direction. The upper end opening of the guide pipe 72 communicates with the extension oil chamber 70a through an annular communication hole 72a formed in the rod guide 71a, and the lower end opening has an introduction hole 74a and an outlet hole 74b of the guide member 74. Through the storage chamber 70c.

The guide member 74 is a plate-like member having an outer surface formed in an arc shape when viewed in the cylinder axis direction (see FIG. 4), and the guide member 74 and the guide member 74 are attached before the rod guide 71a is mounted. By inserting the guide pipe 72 between the cylinder 70 and the outer cylinder 71, the guide pipe 72 is held by the support pieces 73 a of the support body 73. The support body 73 has a cylindrical shape, and is inserted into the outer cylinder 71 in a direction perpendicular to the cylinder axis and fixed by welding.

The damping force control valve 110 is a so-called external type mounted on a lower portion of the outer surface of the outer cylinder 71, and the hydraulic oil in the cylinder 70 is supplied to the guide pipe 72 during both the compression stroke and the expansion stroke. , Introduction hole 74
a, it flows into the storage chamber 70c through the main valve 18 of the control valve 110 and the outlet hole 74b.

The damping force control valve 110 is assembled in the following procedure. First, rubber seals 75 a, 7 are provided on the outer peripheral surface and the inner peripheral surface in the support body 73.
5b inserts the sealing member 75 to which the baking is fixed, and the inner surface of the sealing member 75 in the arc shape is guided by the guide member 74.
To the outer surface of the circular arc. And the outer body 15
A sub-assembly unit in which a main valve 18, an intermediate body 16, a pilot valve 6, a linear solenoid 7, and the like are pre-assembled in the outer and inner bodies 15, 17 is inserted into the support body 73. Insert from. Further, the tip of the inner body 17 is pressed against the seal member 75 by screwing the lid body 8 onto the support body 73. The space between the outer body 15 and the support member 73 is sealed by a seal member 76.

The main valve 18, the intermediate body 16, and the pilot valve 6 are arranged in a stack in the inner body 17, and a space surrounded by the main valve 18, the intermediate body 16, and the pilot valve 6 is formed. A back pressure chamber A for applying a back pressure to the main valve 18 is provided.

The inner body 17 has a cylindrical shape with a bottom. The bottom wall of the inner body 17 communicates with an introduction hole 74a of the guide member 74 to apply the pressure of the expansion oil chamber 70a to the main valve 18. An introduction opening 17a is formed.

The main valve 18 is provided on a back surface of the base plate 19 with a plurality of leaf valves 20a made of leaf springs and having different thicknesses and diameters.
The plate-valve laminated body 20 formed by laminating them is brought into contact with each other, and the bolt 21 and the nut 22 inserted into the shaft center are tightened and fixed by interposing a ring 21c between the head 21b and the plate-valve laminated body 20. Things. The bolt 21 is formed with a pressure guiding hole 21a for introducing the pressure on the extension oil chamber 70a side into the back pressure chamber A.

The base plate 19 is disk-shaped, and has a plurality of introduction holes 19a formed therein at predetermined angular pitches, and a plurality of notch grooves 19b formed at the outer peripheral edge at predetermined angular pitches. Is formed. In the plate valve laminate 20, the introduction hole 19a is closed by a predetermined initial urging force to be described later by the outer peripheral edge of the plate valve 20a having the maximum diameter.

A dump plate 23 is disposed on the back surface of the plate valve laminate 20 of the bolt 21. The dump plate 23 defines the back pressure chamber A into a portion on the pilot valve 6 side and a portion A ′ on the plate valve laminate 20 side of the main valve 18 and has a function of an orifice to form the plate valve laminate 20. Vibration is prevented. An orifice 23a for damping the main valve (for preventing vibration) is formed between the outer peripheral edge of the dump plate 23 and the annular projection 16d of the intermediate body 16. The inner peripheral edge of the dump plate 23 is slightly slidable in the axial direction of the bolt 21 by the thickness of the ring 21c, so that when the pressure of the back pressure chamber portion A 'reaches a predetermined value, the dumping The inner peripheral edge portion of the plate 23 opens to function as a relief valve.

The intermediate body 16 has an opening 16a at the center of the disk where the head 21b of the bolt 21 is located, and is formed in an annular shape with a flange 16b formed upright on the periphery. An annular shim 25 is interposed between the flange portion 16b of the intermediate body 16 and the outer peripheral edge of the base plate 19 of the main valve 18. A seal ring 24 made of an elastic member is inserted and disposed in a portion surrounded by the shim 25, the flange portion 16b of the intermediate body 16, and the bottom surface. The seal ring 24 is made of rubber and has an annular shape having a groove having a V-shaped cross section. One lip 24 a constituting the groove is in contact with the bottom surface of the intermediate body 16. The other lip 24b is pressed against the back surface of the valve plate 20a with a predetermined elastic force, and an initial load is applied to the valve plate 20a of the main valve 18 by the elastic force.

Here, the plate valve 20a of the present embodiment is formed flat and is set to an initial load of 0, and the initial load of the entire plate valve laminate 20 is determined by the above-described seal ring 24. The initial load can be adjusted by replacing the seal ring 24 with one having a different hardness and elastic force, or by changing the shim 25 with a different thickness.

The pilot valve 6 has a valve seat plate 26
And a valve element 27 for opening and closing the valve hole 26a.
The valve seat plate 26 has a disk shape, and the valve hole 26a is formed through the axis thereof. A relief hole 26 formed in the valve seat plate 26 is provided downstream of the valve hole 26a.
b, a relief groove 16c recessed in the intermediate body 16, an orifice 29 for adjusting the flow rate, a gap between the inner body 17 and the seal member 75, and a lead-out hole 74b, which communicate with the storage chamber 70c.

The valve body 27 is a rod having a conical sealing surface 27a for opening and closing the valve hole 26a.
The plunger portion 27b of the valve body 27 is connected to the linear solenoid 7. The linear solenoid 7 is built in the outer body 15 and, when excited, applies a closing direction force corresponding to the exciting force to the valve body 27 via the plunger 27b. By controlling the exciting force, the pressure in the back pressure chamber A at which the valve body 27 starts to open changes, and the control of the exciting force functions as a damping force varying unit. The exciting force is controlled by the magnitude of the current transmitted to the linear solenoid 7 via the electric wiring 13.

Next, the operation of the shock absorber 120 of the present embodiment will be described. When the wheel 2 is pushed up by a convex portion of a road surface and the shock absorber 120 is in a compression stroke, the piston rod 10 and the piston 90 are moved into the cylinder 70 as shown in FIG.
2, the cylinder volume is reduced by the volume of the piston rod 10 and the one-way valve 90a is provided.
b and the expansion-side oil chamber 70a are boosted, and this cylinder pressure acts on the main valve 18 via the guide pipe 72 and the introduction hole 74a, and is introduced into the back pressure chamber A through the pressure introduction hole 21a. The pressure in the back pressure chamber A is also increased, and this pressure is applied to the plate valve laminate 2.
Acts on the back of 0. The elastic force of the seal ring 24 also acts on the outer peripheral edge of the plate valve 20a having the maximum diameter.

When the opening direction force acting on the valve body 27 due to the internal pressure of the back pressure chamber A exceeds the urging force of the linear solenoid 7, the valve body 27 opens the valve hole 26a and the back pressure chamber A
The main valve 18 is pushed open by the difference between the pressure of the introduction hole 19a and the elastic force of the seal ring 24, whereby the hydraulic oil is supplied by the guide pipe 72 and the control valve 110 by an amount corresponding to the piston rod entry volume. Through the storage room 70
and at this time, a pressure damper damping force corresponding to the above-mentioned cylinder pressure × piston rod cross-sectional area is generated.

When the wheel 2 is lowered and the shock absorber 120 is extended, the piston 90 is relatively pulled upward. In this case, since the one-way valve 90a is closed, the expansion side oil chamber 70a is pressurized, and the expansion side pressure is increased by the guide pipe 72,
It acts on the main valve 18 through the introduction hole 74a, and is introduced into the back pressure chamber A through the pressure guiding hole 21a, and the pressure in the back pressure chamber A also increases.

When the opening force acting on the valve body 27 due to the internal pressure of the back pressure chamber A exceeds the biasing force of the linear solenoid 7, the valve body 27 opens the valve hole 21a and the internal pressure of the back pressure chamber A decreases. The main valve 18 is pushed open by the difference between the pressure of the introduction hole 19a and the elastic force of the seal ring 24, whereby the hydraulic oil flows from the expansion oil chamber 70a into the storage chamber 70c. X: An extension damper damping force corresponding to (piston area-piston rod area) is generated. The hydraulic oil in the reservoir 70c is filled with the check valve 64 in the pressure side oil chamber 7b.
Replenished through.

In the present embodiment, the main valve 18 has a structure in which the introduction hole 19a is closed by the plate valve laminated body 20, so that the conventional main valve is formed in a cylindrical shape, and is provided in a limited space in the cylinder. The spring constant of the main valve 18 can be easily increased as compared with the one accommodating the return coil spring, and the responsiveness when a damping force occurs can be improved.

The initial load of the plate valve laminate 20 itself is set to 0, and the seal ring 24 made of an elastic member is brought into contact with the back surface of the plate valve 20a to set the initial load.
The initial load can be set more accurately than the conventional coil spring, the setting of the damping force in the rising region is easy and reliable, the main valve 18 opens smoothly, and the ride comfort is improved. Can be improved. That is, the plate valve 20a of the present embodiment is simply formed of a flat plate, and it is easy to accurately set the initial load to zero. On the other hand, when trying to set the initial load with a coil spring, an error tends to occur in the initial load depending on the diameter and length of the coil spring.

The main valve 18 of the present embodiment has a structure in which the introduction hole 19a is opened and closed by a plate valve 20a having a simple shape. Therefore, the structure is simple and the cost can be avoided. Even if dust is caught between the hole 19a and the peripheral portion thereof, the dust easily flows, so that there is no problem of malfunction due to the dust being caught.

[0035]

[Brief description of the drawings]

FIG. 1 is a schematic view of a suspension system employing a damping force variable control type shock absorber according to an embodiment of the present invention.

FIG. 2 is a sectional side view of the shock absorber.

FIG. 3 is a sectional side view of a damping force control valve of the shock absorber.

FIG. 4 is a sectional plan view of the damping force control valve.

FIG. 5 is a schematic configuration diagram showing a conventional general damping force variable control type shock absorber.

[Explanation of symbols]

 Reference Signs List 6 pilot valve 7 solenoid (control means) 18 main valve 19 base plate 19a introduction hole 20 plate valve laminated body 20a plate valve 24 seal ring 26a valve hole (pilot passage) 70 cylinder 70a extension oil chamber 70b pressure oil chamber 70c storage chamber 72 Guide pipe (communication passage) 90 Piston 120 Variable damping force control type shock absorber A Back pressure chamber

Claims (2)

[Claims] A main valve that opens and closes a communication path that communicates between an expansion-side oil chamber defined by a piston in a cylinder and a storage chamber that stores excess hydraulic oil; and a main valve that is formed on a back side of the main valve. A back pressure chamber communicating with the extension oil chamber; a pilot valve for opening and closing a pilot passage communicating the back pressure chamber with the storage chamber; and control means for variably controlling a pilot passage closing force by the pilot valve. In the variable damping force control type shock absorber, the main valve has a base plate that forms a back pressure chamber with the pilot valve, and an introduction hole that connects the extension side oil chamber and the back pressure chamber is formed. And a plate valve stack formed by stacking a plurality of plate valves having different diameters from each other on the back pressure chamber side of the base plate and the introduction hole can be opened and closed. The flow resistance of the communication passage is determined by the force and the back pressure in the back pressure chamber. A damping force variable control type shock absorber characterized in that it is variably controlled. 2. The plate valve according to claim 1, wherein an annular seal ring made of an elastic body is disposed so as to abut against an outer peripheral edge of a back surface of the plate valve, and an initial load is applied to the plate valve by the elastic force of the seal ring. A damping force variable control type shock absorber characterized by being acted on.