JPH0783265A - Damping force adjusting type hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To lessen the operating and holding forces of a shutter in the damping force adjusting valve of an attenuation adjusting type hydraulic shock absorber. CONSTITUTION:A piston 8 connected with a piston rod 9 is fitted in a cylinder 7 filled with hydraulic oil. The piston 8 is provided with an extension/ contraction side main oil passages 11 and 14 (great damping force), and the piston rod 9 is provided with a bypass passage B (small damping force). A shutter 23 is rotated, and the area of a passage communicating guide ports 21 and 22 with shutter ports 24 and 25 is changed to adjust the passage area of the bypass passage B, so that damping force is thereby changed over. A bulkhead 34 is provided within the shutter 23, so that guide wall sections 35 faced to the shutter ports 24 and 25 are thereby formed. Hydraulic oil flowing into the shutter 23 from the shutter ports 24 and 25 is turned over by the guide wall section 35, hydraulic oil is concurrently directed roughly to the vertical direction with respect to the circumferential direction of the shutter 23, and fluid force acting to the rotating direction of the shutter 23 is made small, so that the operating and holding forces of the shutter 23 are thereby lessened.

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. As shown in FIGS. 5 to 7, the damping force adjusting 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 FIGS. 6 and 7, the guide port 4 and the shutter port 5
Are provided on the side walls of the guide member 2 and the shutter 3 at positions different from each other by 180 °, and the shutter 3 is balanced by balancing the pressure of the oil liquid acting on the shutter 3.
Can rotate smoothly.

[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
When 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 flows in the radial direction through the shutter port 5 and flows into the shutter port 5 along the outer peripheral surface of the shutter 3. 7 and the resultant force of these oil liquid flows results in a jet flow in the direction indicated by the arrow in FIG.
Flows into the inside of. The oil liquid passing through this orifice has a very high flow velocity, and near the end of the shutter port 5 on the guide port 4 side (the portion indicated by a in FIG. 7), the momentum associated with the increase in the flow velocity of the oil liquid is The pressure decreases due to the change, and in the vicinity of the end portion on the opposite side of the shutter port 5 (the portion indicated by b in FIG. 7), the pressure increases due to the dynamic pressure of the oil liquid flowing into the shutter 3. And the shutter 3
A fluid force is generated by a change in the internal pressure, and a clockwise rotational force in FIG. 7 acts on the shutter 3, which causes a problem that the positioning accuracy of the shutter 3 is reduced. 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.

Incidentally, the guide port 4 and the shutter port 5
The steady-state fluid force F in the circumferential direction of the shutter 3, which is generated by the oil liquid flowing through the orifice formed by, is the density ρ of the oil liquid, the flow rate Q, the flow velocity V, the sliding surface between the guide member 2 and the shutter 3, and the oil. When the liquid flow angle is θ, it can be approximately expressed by the following equation. F = ρQV · cos θ (1) Since the guide port 4 and the shutter port 5 are provided in pairs, if the diameter of the shutter 3 is d, a rotational force F · d is applied to the shutter 3 by a fluid force. Will work.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a damping force adjustable hydraulic shock absorber designed to reduce the fluid force acting on the shutter of the damping force adjusting valve. To do.

[0009]

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 container, the damping force adjusting valve includes a cylindrical guide member having a guide port on the side wall, and a shutter having a shutter port rotatably fitted to the guide member and facing the guide port on the side wall, By rotating the shutter, the orifice area formed by the guide port and the shutter port is changed to adjust the passage area of the bypass passage. A guide for generating a swirl flow in the oil liquid flowing from the shutter port in the shutter and guiding the oil liquid so that the oil liquid flow is in a direction substantially perpendicular to the circumferential direction of the shutter. It is characterized by having a wall portion.

[0010]

With this structure, the oil liquid flowing into the shutter from the orifice formed by the guide port and the shutter port forms a swirl flow by the guide wall portion, and the inflow direction is the circumferential direction of the shutter. On the other hand, since it is in a substantially vertical direction, the fluid force acting in the rotation direction of the shutter becomes small.

[0011]

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.

Inside the passage member 10, a substantially cylindrical guide member is provided.
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, and as the shutter 23 is rotated to one side from this state, 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, and the damping force adjusting hydraulic shock absorber 6 is provided. 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, the guide member 16 and the shutter 23 constituting the damping force adjusting valve, which is the main part of this embodiment, will be described in more detail.

The shutter 23 is provided with a partition wall 34 that divides the interior of the shutter 23 into two parts.
In the shutter 23, a pair of guide wall portions 35 facing the pair of shutter ports 24, 25 arranged at 180 ° different positions are formed. As shown in FIG. 1, the guide wall portion 35 includes the guide ports 21, 22 and the shutter port 24,
25 and (in FIG. 1, guide port 21 and shutter port 24
(Only shown in the figure) forms a space having a shape and volume such that the oil liquid flowing into the shutter 23 flows along the wall surface to generate a swirling flow, and flows into the shutter 23 from the orifice. The flow of the oil liquid is substantially perpendicular to the circumferential direction of the shutter 23 (the angle θ between the flow direction of the oil liquid shown by the arrow in FIG. 1 and the circumferential direction of the shutter 23 is substantially right angle). It is designed to guide the flow of liquid.

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 guide wall portion 35 provided on the shutter 23 of the damping force adjusting valve, which is an essential part of the present invention, will be described. Since the guide wall portion 35 acts similarly on the orifice formed by the guide port 21 and the shutter port 24 and the orifice formed by the guide port 22 and the shutter port 25, the guide port 21 and the shutter port will be described below. Only 24 will be explained.

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 orifices of and is reduced, during the extension stroke of the piston rod 9, the oil liquid in the oil passage 19 passes through the orifice formed by the guide port 21 and the shutter port 24 to form a jet flow into the shutter 23. Inflow. This jet is
As indicated by the arrow in FIG. 1, a swirling flow is generated in the flow guide wall portion 35 along the partition wall 34. Then, the inflow direction of the jet from the orifice is substantially perpendicular to the circumferential direction of the shutter 23 (approximately θ = 90 °) due to the flow of the oil liquid swirling in the guide wall portion 35. Therefore, in the equation (1), since θ = 90 °, the fluid force F acting on the shutter 23 becomes almost 0, and the rotational force due to the fluid force hardly acts on the shutter 23. Power is reduced.

The shapes of the partition wall 34 and the guide wall portion 35 formed on the shutter 23 are not limited to those shown in FIG. 1, and flow into the shutter 23 through the orifice formed by the guide port 21 and the shutter port 24. Swirl the jet of oil liquid,
It suffices that the inflow direction be substantially perpendicular to the circumferential direction of the shutter 23.

Another embodiment of the shapes of the partition wall 34 and the guide wall portion 35 will be described with reference to FIG. As shown in FIG. 4, the surface of the partition wall 34 facing the shutter port 24 is a flat surface,
The width W ₂ of the guide wall 35 is the width W ₁ of the opening of the shutter port 24.
The corners of the bottom of the guide wall 35 are rounded (R ₁ , R ₂ ), so that the swirling flow is smoothly formed. Here, the width W ₂ of the guide wall portion 35, when the difference between W ₁ and W ₂ is about 7% of W _1, i.e., becomes substantially _{(W 2 -W 1) / W} 1 = 0.07 In such a case, the swirling flow can be effectively generated. Further, when the depth D of the bucket is about one half of the radius R inside the shutter 23, that is, when D / R = 0.5, the swirl flow is effectively formed. If you are deeper than this, the effect will be less, and if it is deeper than this, the effect will not change much.

In the present 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.

In the present embodiment, the case where the damping force adjusting valve is provided in the piston 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.

[0035]

As described above in detail, in the damping force adjusting hydraulic shock absorber of the present invention, since the shutter of the damping force adjusting valve is provided with the guide wall portion, the orifice formed by the guide port and the shutter port. The oil liquid flowing from the inside of the shutter into the shutter generates a swirling flow by the guide wall portion, and its inflow direction is guided in a direction substantially perpendicular to the circumferential direction of the shutter, so that the fluid force acting in the rotating direction of the shutter is generated. Becomes smaller. 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]

FIG. 1 is a view showing a cross section of a damping force control valve, which is a main part of an embodiment of the present invention, and is a cross section of the guide member and the shutter of FIG.

FIG. 2 is a front view of a guide member and a port portion of a shutter of the apparatus of FIG.

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 lateral cross-sectional view showing an enlarged guide wall of a shutter of another embodiment of the present invention.

FIG. 5 is an exploded perspective view of a guide member and a shutter, which are damping force adjusting valves of a conventional damping force adjusting hydraulic shock absorber.

FIG. 6 is a longitudinal sectional view of a guide member and a shutter, which are damping force adjusting valves of a conventional damping force adjusting hydraulic shock absorber.

FIG. 7 is a cross-sectional view of the guide member and the port portion of the shutter 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 35 Guide wall B Bypass passage

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. -Shaped guide member and a shutter rotatably fitted to the guide member and having a shutter port on the side wall facing the guide port, and the orifice area formed by the guide port and the shutter port by the rotation of the shutter. Is adjusted to adjust the passage area of the bypass passage, and the oil flowing from the shutter port into the shutter is further adjusted. Damping force characterized by including a guide wall portion that generates a swirl flow in the liquid flow and guides the oil liquid so that the flow of the oil liquid is substantially perpendicular to the circumferential direction of the shutter. Adjustable hydraulic shock absorber.