JPH0777233A - Damping force adjustable hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To relieve the operating force and holding force of a shutter in a damping force adjusting valve of a damping adjustable hydraulic shock absorber. CONSTITUTION:A piston 8 connected with a piston rod 9 is fitted in a cylinder 7 sealed with a hydraulic fluid. Two main hydraulic fluid passages 11 and 14 (large in damping force) at both expansion and contraction sides are installed in this piston 8, installing a bypass passage B (small in damping force) is installed in the piston rod 9. A shutter 23 is rotated, and an orifice area between two guide ports 21 and 22 and shutter ports 24 and 25 is varied, thereby adjusting a passage area of the bypass passage B, and thereby damping force is selected. Each of inclined walls 34 and 35 along an inflow angle of a hydraulic fluid flowing into the shutter 23 from an orifice is installed in an end part forming this orifice in and around a valve-close position of these shutter ports 24 and 25. Since the hydraulic fluid flows into the shutter 23 along these inclined walls 34 and 35, a low pressure part is hard to be produced nearby these shutter ports 24 and 25, so that fluid force acting on the shutter 23 becomes lessened, whereby operating force and holding force are well relieved.

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 both the expansion side and the contraction side are small. A damping force is generated, and the damping force characteristic becomes a soft characteristic. When the damping force adjustment valve is closed, the piston slides as the piston rod expands and contracts, causing the oil in the cylinder to flow only through the main oil passage, producing a large damping force on both the expansion and contraction sides. 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.

An example of the damping force adjusting valve of the conventional damping force adjusting type hydraulic shock absorber as described above will be described below with reference to FIGS. 4 and 5. As shown in FIGS. 4 and 5, the damping force control valve 1 includes a cylindrical guide member 2 and a guide member 2.
The guide member 4 is provided with a guide port 4 on the side wall of the guide member 2, and the shutter port is opposed to the guide port 4 on the side wall of the shutter 2. 5 are provided. The guide port 4 and the shutter port 5 form a part of the bypass passage. By rotating the shutter 3 to change the area of the orifice formed by the guide port 4 and the shutter port 5, the bypass passage is formed. The passage area of is adjusted. As shown in FIG. 5, a pair of the guide port 4 and the shutter port 5 are provided at positions different by 180 ° on the side walls of the guide member 2 and the shutter 3 to balance the pressure of the oil liquid acting on the shutter 3. By doing so, the shutter 3 can be smoothly rotated.

[0006]

However, the damping force adjusting hydraulic shock absorber having the conventional damping force adjusting valve 1 has the following problems. That is, the guide port 4
In the vicinity of the valve opening start position where the area of the orifice formed by the shutter port 5 and the shutter port 5 is small, the oil liquid passing through this orifice has a very high flow velocity and becomes a jet flow in the direction indicated by the arrow in FIG. Flows into the inside of. Then, in the vicinity of the port opening start side port wall 5A of the shutter port 5 (the portion indicated by a in FIG. 5), the pressure decreases due to the change in momentum accompanying the increase in the flow rate of the oil liquid, and the shutter port 5 In the vicinity of the port wall 5B on the side opposite to the valve opening start position side port wall 5A (the portion indicated by b in FIG. 5), the pressure rises due to the dynamic pressure of the oil liquid flowing into the shutter 3. Then, a fluid force is generated by the pressure change in the shutter 3,
A clockwise rotational force in FIG. 5 acts on the shutter 3, and this rotational force causes a problem that the positioning accuracy of the shutter 3 decreases. Therefore, it is necessary to increase the output of an actuator (not shown) that operates the shutter 3 in order to operate and position the shutter 3 against the rotational force of the fluid force. Further, since this fluid force changes depending on the area of the communication passage between the guide port 4 and the shutter port 5, there arises a problem that it becomes difficult to control the passage area.

The present invention has been made in view of the above points, and provides a damping force adjustable hydraulic shock absorber that reduces the rotational force due to the fluid force acting on the shutter of the damping force adjusting valve. With the goal.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention makes two cylinder chambers communicate with each other by a main oil liquid passage and a bypass passage, and the piston in the cylinder slides to cause the main oil liquid to flow. A damping force adjustable hydraulic buffer capable of adjusting the damping force by controlling the flow of the oil liquid generated in the passage and the bypass passage to generate a damping force and adjusting the passage area of the bypass passage by the damping force adjusting valve. In the device, the damping force adjusting valve includes a cylindrical guide member having a guide port on a side wall, and a shutter having a shutter port rotatably fitted in the guide member and facing the guide port on the side wall. In the transverse cross section of the valve opening start position at the time of opening the damping force adjusting valve,
The line formed by the port opening start position side port wall of the shutter port is on the side facing the valve opening start position side port wall of the shutter port with respect to the line formed by the guide port valve opening start position side port wall. It is characterized by being inclined toward the port wall.

[0009]

With this structure, the oil liquid flowing into the shutter from the orifice formed by the guide port and the shutter port smoothly flows along the inclination of the port wall on the shutter port opening start position side. Since the low pressure portion is less likely to be generated in the vicinity of the valve opening start position side port wall of the shutter port in the guide member, the generation of the low pressure portion reduces the fluid force acting in the rotational direction of the shutter.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 3, in the damping force adjusting hydraulic shock absorber 6 of this embodiment, a piston 8 is slidably fitted in a cylinder 7 in which an oil liquid is sealed.
The inside of the cylinder 7 depends on the cylinder upper chamber 7a and the cylinder lower chamber.
It is divided into two rooms, 7b. One end side of a piston rod 9 penetrates through the piston 8, and the piston rod 9
The cylindrical passage member 10 is fixed to the piston 8 by screwing the cylindrical passage member 10 at its tip. The other end of the piston rod 9 is inserted into a rod guide (not shown) and a seal member (not shown) provided at the end of the cylinder 7 and extends to the outside of the cylinder 7. In addition, the cylinder 7 has a piston rod 9 that moves in and out.
A reservoir chamber (not shown) is provided for compensating the volume change therein by compressing and expanding the gas.

The piston 8 is provided with an extension-side main oil liquid passage 11 and a compression-side main oil liquid passage 12 which connect the cylinder upper chamber 7a and the cylinder lower chamber 7b. And piston 8
A damping force generation mechanism 13 including an orifice and a disc valve that controls the flow of the oil liquid in the extension-side main oil liquid passage 11 to generate a damping force is provided on the end surface of the cylinder lower chamber 7b side of the piston. A damping force generation mechanism 14 including a disk valve that controls the flow of the oil liquid in the compression-side main oil liquid passage 12 to generate a damping force is provided on the end surface of the cylinder 8 on the cylinder upper chamber 7a side.

The piston rod 9 has a passage member whose one end communicates with the cylinder upper chamber 7a and whose other end communicates with the cylinder lower chamber 7b.
An oil liquid passage 15 communicating with the inside of 10 is provided.
A bypass passage B that connects the cylinder upper chamber 7a and the cylinder lower chamber 7b is constituted by 15 and the passage member 10.

A substantially cylindrical guide member is provided in the passage member 10.
16 is mated. Then, one end of the guide member 16 is provided with a check valve 17 that allows the flow of the oil liquid from the inside of the guide member 16 to the cylinder upper chamber 7a side and blocks the flow in the opposite direction, and the other end thereof. A check valve 18 is provided in the guide member 16 to allow the oil liquid to flow from the guide member 16 to the cylinder lower chamber 7b side and prevent the oil liquid from flowing in the opposite direction.

In the bypass passage B, between the passage member 10 and the guide member 16, an oil liquid passage 19 communicating with the cylinder upper chamber 7a side and an oil liquid passage 20 communicating with the cylinder lower chamber 7b side.
Are formed on the side wall of the guide member 16 at 180 ° different positions communicating with the pair of guide ports 21 communicating with the oil liquid passage 19 and 180 ° different positions. A pair of guide ports 22 are provided. The oil liquid passage 19 and the guide port 21 bypass the check valve 17, and the oil liquid passage 20 and the guide port 22 bypass the check valve 18.

A cylindrical shutter 23 is provided in the guide member 16.
Are rotatably fitted together. On the side wall of the shutter 23,
A pair of shutter ports 24 are provided facing the guide port 21 of the guide member 16, and a pair of shutter ports 25 are provided facing the guide port 22. The shutter ports 24 and 25 are each extended in the circumferential direction of the shutter 23, and the shutter port 24 is formed in a substantially wedge shape whose diameter increases toward one side. It is formed in a substantially wedge shape whose diameter increases toward the opposite side. Then, by rotating the shutter 23, the guide port 21 and the shutter port 24
The area of the orifice formed by the alignment of the guide port 22 and the shutter port 25 is adjusted by changing the area of the orifice formed by the alignment of the guide valve 22 and the shutter port 25. Check valve
The passage area of the oil passage for bypassing 18 is adjusted.

In this case, when the orifices of the guide port 21 and the shutter port 24 are fully opened, the orifices of the guide port 22 and the shutter port 25 are fully closed. From this state, as the shutter 23 is rotated to one side, the guide port is closed.
The area of the orifice between the guide port 22 and the shutter port 24 becomes small at the same time as the area of the orifice between the guide port 22 and the shutter port 24 becomes large.
The orifice between the shutter port 25 and the shutter port 25 is fully opened.

An operating rod 26 is connected to the shutter 23, and the operating rod 26 penetrates the check valve 17 and extends along the piston rod 9 to the outside thereof. The shutter 23 can be rotated from the outside by an actuator (not shown) or the like via the operation rod 26. The shutter 23 is made up of three members.
23a, 23b, 23c are joined by an operating rod 26. In the figure, 27 is a bearing that rotatably supports the shutter 23 with a small torque, and an oil liquid passage is formed in the inner peripheral portion thereof.

A valve body 28 is fitted into an opening of the passage member 10 on the cylinder lower chamber 7b side, and is fixed by a screw member 29. The valve body 28 is provided with an oil liquid passage 30 and an oil liquid passage 31 which connect the inside of the passage member 10 and the cylinder lower chamber 7b. Then, at both ends of the valve body 28, a damping force generating mechanism 32 including an orifice for controlling the flow of the oil liquid in the oil liquid passage 30 to generate a damping force and a disc valve, and a cylinder lower chamber of the oil liquid passage 31. A check valve that allows the oil liquid to flow from the 7b side to the inside of the passage member 10.
33 are provided.

Next, regarding the guide member 16 and the shutter 23 which constitute the damping force adjusting valve which is the main part of this embodiment, it is a concave cross-sectional view of the valve opening start position at the time of starting the opening of the damping force adjusting valve. This will be described in more detail with reference to FIG. 1 and FIG. 2 which is a front view of the port portion when the damping force adjusting valve field is opened.

As shown in FIGS. 1 and 2, the shutter 23
When the shutter port 24 of the shutter valve 24 is at the valve opening start position, the wedge-shaped end portion of the wedge forming an orifice with the guide port 21 is inclined so that the inclined wall 34 (the port wall of the shutter 23 at the valve opening start position side) is inclined. ) Has been formed. That is, the inclined wall 34 is a port wall on the side where the line formed by the inclined wall 34 faces the inclined wall 34 by an angle α with respect to the line m formed by the port wall 21A on the valve opening start position side of the guide port 21. It is inclined toward the 34A side. And again, this inclined wall 34
Guide port 21 and shutter port at the valve opening start position
The angle is substantially along the inflow angle θ of the oil liquid (indicated by the arrow in FIG. 1) flowing into the shutter 23 from the orifice formed by 24 and.

The shutter port 25 is also provided with an inclined wall 35 similar to the shutter port 24.

The operation of this embodiment having the above-mentioned structure will be described below.

The shutter is operated by operating the operation rod 26 from the outside.
The damping force characteristics can be switched by rotating 23.

The shutter 23 is rotated to fully open the orifices of the guide port 21 and the shutter port 24.
When the orifice between 22 and the shutter port 25 is fully closed, the bypass passage B is used when the piston rod 9 extends.
In the inside, the oil liquid on the cylinder upper chamber 7a side is closed by closing the check valve 17 and the oil liquid passage 19, the guide port 21, and the shutter port.
24, and further, the check valve 18 is opened to flow through the oil liquid passage 30 of the valve body 28 to the cylinder lower chamber 7b side. Therefore, a small damping force is generated by the area of the orifice between the guide port 21 and the shutter port 24 and the damping force generation mechanism 32. On the other hand, during the contraction stroke of the piston rod 9, the check valve 18 is closed and the orifices of the guide port 22 and the shutter port 25 are closed, so the bypass passage B is closed. Therefore, the oil liquid flows only through the compression-side main oil liquid passage 12 of the piston 8, and a large damping force is generated by the damping force generation mechanism 14. Therefore, the damping force characteristic is a soft characteristic on the extension side and a hard characteristic on the contraction side.

The shutter 23 is rotated to one side from the above position to reduce the area of the orifice between the guide port 21 and the shutter port 24, and the guide port 22 and the shutter port 25.
When the orifices of and are opened, during the extension stroke of the piston rod, in the bypass passage B, the oil liquid on the cylinder upper chamber 7a side flows to the cylinder lower chamber 7b side in the bypass passage B, and the guide port 21 and the shutter are released. The damping force increases as the area of the orifice with the port 24 decreases. On the other hand, during the compression stroke of the piston rod 9, the bypass passage B
In the inside, the oil liquid on the cylinder lower chamber 7b side is
The check valve 33 is opened, the check valve 18 of the guide member 16 is closed to flow through the oil passage 20, the guide port 22 and the shutter port 25, and the check valve 17 is opened to the cylinder upper chamber 7a side. Flowing. Therefore, a portion opened by the guide port 22 and the shutter port 25 becomes an orifice, and a small damping force (orifice characteristic) corresponding to the orifice area is generated. Therefore, the damping force characteristics are medium characteristics on both the extension side and the contraction side.

When the shutter 23 is rotated further to the one side from the above position, the orifices of the guide port 21 and the shutter port 24 are fully closed, and the orifices of the guide port 22 and the shutter port 25 are fully opened, the piston rod 9 During the extension stroke, the check valve 17 is closed and the orifices of the guide port 21 and the shutter port 24 are closed, so the bypass passage B is closed. Therefore, the oil liquid flows only through the extension side main oil liquid passage 11 of the piston 8 and a large damping force is generated by the damping force generation mechanism 13. On the other hand, during the compression stroke of the piston rod 9, in the same way as above, the oil liquid on the cylinder lower chamber 7b side flows to the cylinder upper chamber 7a side in the bypass passage B, and the orifices of the guide port 22 and the shutter port 25 are formed. Damping force (orifice characteristic) as much as the area of
Becomes smaller. Therefore, the damping force characteristics are hard characteristics on the extension side and soft characteristics on the contraction side.

In this way, different damping force characteristics can be set on the expansion side and the contraction side, and further, the guide port 21 and the shutter port 24, the guide port 22 and the shutter port 25 can be set according to the rotation angle of the shutter 23. Since the area of the orifice formed in 1 can be continuously changed, the damping force characteristics can be continuously adjusted by changing the passage areas of the extension side and contraction side bypass passages B. In addition,
Guide port 21 and guide port 22 by shutter 23
Can be closed and the bypass passage B can be closed to expand and contract to provide hard characteristics on both sides.

Next, the operation of the inclined walls 34 and 35 provided on the shutter ports 24 and 25 of the damping force adjusting valve, which is the main part of the present invention, will be described. Since the inclined walls 34 and 35 act similarly on the oil liquid that forms the orifice formed by the guide port 21 and the shutter port 24 and the oil liquid that flows through the orifice formed by the guide port 22 and the shutter port 25, Hereinafter, only the one inclined wall 34 will be described.

As shown in FIGS. 1 and 2, the shutter 23
1 side to rotate the guide port 21 and shutter port 24
When the area of the orifice of and is made small near the valve closing position, the oil liquid in the oil liquid passage 19 flows through the orifice formed by the guide port 21 and the shutter port 24 during the extension stroke of the piston rod 9. And flows into the shutter 23. At this time, the shutter port that forms the orifice
Since the inclined wall 34 of 24 is inclined along the inflow angle θ of the oil liquid, the jet of the oil liquid smoothly flows along the inclined wall 34. Therefore, in the vicinity of the shutter port 24, the conventional example of FIG. It becomes difficult for a pressure drop portion such as the portion a shown in FIG. Therefore,
Since the rotational force due to the fluid force hardly acts on the shutter 23, the operating force and the holding force of the shutter 23 are reduced.

In this embodiment, the case where the present invention is applied to the damping force adjusting type hydraulic shock absorber capable of setting different damping force characteristics on the extension side and the contraction side has been described. It can be similarly applied to a normal damping force adjusting hydraulic shock absorber that adjusts the damping force by adjusting the passage area of the bypass passage common to the extension side and the contraction side.

In this embodiment, the case where the damping force adjusting valve is provided in the piston portion has been described, but the present invention is not limited to this, and the bypass passage is provided outside the cylinder and the damping force adjusting valve is provided in the cylinder. It can also be applied to those provided outside the.

[0033]

As described in detail above, in the damping force adjusting hydraulic shock absorber of the present invention, the shutter opening of the damping force adjusting valve is provided with the port wall on the valve opening start position side inclined.
The oil liquid flowing into the shutter from the orifice formed by the guide port and the shutter port smoothly flows along the slope of the port wall on the valve opening start position side of the shutter port. Since the portion is less likely to be formed, the fluid force acting in the sliding direction of the shutter is reduced due to the generation of the low pressure portion. As a result, the positioning accuracy of the shutter can be improved, and the output of the actuator for operating the shutter can be small, so that the actuator can be miniaturized.

[Brief description of drawings]

1 is a cross-sectional view of a valve opening start position at the time of starting valve opening of a damping force control valve, which is a main part of one embodiment of the present invention, and a cross section taken along line AA of a guide member and a shutter in FIG. It is a side view.

FIG. 2 is a front view of a port portion of the device of FIG. 3 at the start of opening the damping force adjusting valve.

FIG. 3 is a vertical cross-sectional view of a damping force adjusting hydraulic shock absorber showing an embodiment of the present invention.

FIG. 4 is a front view of a port portion of a damping force adjusting valve of a conventional damping force adjusting hydraulic shock absorber.

5 is a cross-sectional view of a port portion of the damping force control valve of FIG.

[Explanation of symbols]

6 Damping force adjustable hydraulic shock absorber 7 Cylinder 7a Cylinder upper chamber (cylinder chamber) 7b Cylinder lower chamber (cylinder chamber) 8 Piston 11 Extension side main oil liquid passage (main oil liquid passage) 12 Compression side main oil liquid passage (main Oil liquid passage) 16 Guide member 21,22 Guide port 23 Shutter 24,25 Shutter port 34,35 Inclined wall (port opening opening side port wall) B Bypass passage m Guide port opening side port wall is formed Line n A line along the inclined wall (a line formed by the port wall on the valve opening start position side of the shutter port)

Claims (1)

[Claims] 1. A damping force by connecting two cylinder chambers with a main oil liquid passage and a bypass passage to control the flow of oil liquid generated in the main oil liquid passage and the bypass passage by sliding of a piston in the cylinder. And a damping force adjusting valve capable of adjusting the damping force by adjusting the passage area of the bypass passage by a damping force adjusting valve, wherein the damping force adjusting valve is a cylinder having a guide port on its side wall. A guide member and a shutter that is rotatably fitted in the guide member and has a shutter port on the side wall that faces the guide port. In the cross-section, the line formed by the port opening start position side port wall of the shutter port is in front of the line formed by the valve opening start position side port wall of the guide port. The damping force adjusting hydraulic shock absorber, wherein the shutter port is inclined toward the port wall on the side opposite to the valve opening start position side port wall.