JPH0469423A - Damping force variable shock absorber - Google Patents

Abstract

PURPOSE:To sufficiently change damping force by providing a valve for opening/ closing the respective ports of each case, rotary valve arranged in a passage of a piston rod to switch a flow direction of fluid between two fluid chambers and an actuator for actuating this rotary valve. CONSTITUTION:A flow direction of fluid between two fluid chambers A, B is switched by arranging a rotary valve 60 in a passage 22 of a piston rod 14. The valve 60 is rotated by an actuator 62 like a solenoid valve built in space 24. The rotary valve 60 is provided with a flange part 61a and a shaft part 61b of circular section integrally formed with the flange part 61a, and three passages 64, 66, 68 are provided in a condition where the shaft part 61b is notched at 120 deg. spaces in the peripheral directions, in the shift part 61b. When flow amount pressure characteristic by valves 38, 40 correlated to an upper case 16 is made different from blow amount pressure characteristic by valves 42, 44 correlated to a lower case 18, damping force speed characteristic as shown by the drawing is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a shock absorber with variable damping force, and particularly to a shock absorber suitable for use in a vehicle suspension system.

(Prior art) A piston disposed inside the cylinder partitions the inside of the cylinder into two liquid chambers, a piston rod connected to the piston is provided with a passage communicating the two liquid chambers, and the inside of this passage is A rotary valve having a plurality of orifices with different orifice diameters is disposed, and a first expansion side damping valve and a compression side damping valve are provided in parallel on the piston,
Furthermore, a second expansion side damping valve and a compression side damping valve are provided in series in the piston via an auxiliary liquid chamber, and the auxiliary liquid chamber and the two liquid chambers are communicated and cut off by a rotary valve and a switching valve. A shock absorber with variable damping force has been proposed (Japanese Patent Publication No. 2-3053).

(Problem to be Solved by the Invention) In the buffer, the liquid flowing through the rotary valve generates a damping force due to the restriction of the orifice, and the differential pressure generated between upstream and downstream of the orifice is equal to 2 Since it is proportional to the power of the piston speed, it is not possible to sufficiently change the damping force in the high piston speed range where the flow rate is large while ensuring the damping force in the low piston speed range where the flow rate is small.

Further, in the shock absorber, a case including second expansion side and compression side damping valves is coupled to the piston, and a switching valve is disposed within the case, and a rotary valve is disposed within the passage of the piston rod. The structure is complicated, and two switching valves are required.

Therefore, an object of the present invention is to provide a variable damping force shock absorber that can sufficiently change the damping force, has a simple structure, and can reduce the number of parts.

(Means for Solving the Problems) A variable damping force shock absorber according to the present invention includes a cylinder, a piston that is movably arranged inside the cylinder and partitions the inside of the cylinder into two liquid chambers, and a piston rod coupled to the piston and having a passage communicating two liquid chambers; and two cases disposed one above the other with the piston in between, each case allowing liquid to flow when the piston rod is extended. two cases that together with the piston define an auxiliary liquid chamber that communicates with the passage of the piston rod and the port of the case; and a port that allows liquid to flow during contraction. , a valve for opening and closing each port of each case, a rotary valve disposed in the passage of the piston rod to switch the direction of liquid flow between the two liquid chambers, and an actuator for operating the rotary valve. including.

(Function and Effect) By rotating the rotary valve, the direction of the flow between the two liquid chambers changes, so that the liquid passes through one valve, two valves in parallel, or two valves in series. It passes through the target and generates different damping forces.

Since the rotary valve switches the direction of liquid flow and does not include an orifice, the flow rate can be determined without considering differential pressure. As a result, it is easy to ensure the damping force in the low piston speed range where the flow rate is low and to sufficiently change the damping force in the high piston speed range where the flow rate is high.

The parts that generate the damping force are the piston, two cases arranged above and below with the piston in between, and valves that open and close the ports of these cases, so the overall structure is simple. In addition, since the piston does not have a port for flowing liquid, it is easy to process the piston, and the upper and lower cases can be used with the same shape as they are, or they can be used upside down. , production efficiency can be improved.

A single rotary valve switches the direction of flow, reducing the number of parts.

(Example) As shown in FIG. 1, the shock absorber includes a cylinder 10, a piston 12, a piston rod 14, and two cases 16 and 18.

The piston 12 is movably arranged inside the cylinder 10, and has a piston bunt 20 attached to its outer peripheral surface. This partitions the inside of the cylinder 10 into an upper liquid chamber A and a lower liquid chamber B. The piston 12 is not provided with a port for flowing liquid.

The piston rod 14 is connected to the piston 12 as described later.
It has a passage 22 that communicates the two liquid chambers A and B. In the illustrated embodiment, the passage 22 has a passage portion 23a communicating with the upper liquid chamber A and extending in the radial direction, and a passage portion 23b communicating with the lower liquid chamber B and extending in the axial direction beyond the piston 12. Consisting of The passage section 23b extends upward into the space 24, and the passage section 23a opens into the passage section 23b.

The two cases 16 and 18 are arranged one above the other with the piston 12 in between. The case 16 has a port 26 through which liquid can flow when the piston rod 14 is extended, and a port 28 through which liquid can flow when the piston rod 14 is retracted. and,
The case 18 has a port 30 through which liquid can flow when the piston rod 14 is extended, and a port 32 through which liquid can flow when the piston rod 14 is retracted.

The case 16 has a hole 35 in the passage 22 of the piston rod 14.
defines an auxiliary liquid chamber 34 communicating with the piston 12 and communicating with the port 26.28 of the case;
On the other hand, the case 18 communicates the hole 37 with the passage 22 through an eaves,
Together with the piston 12, it defines an auxiliary liquid chamber 36 which communicates with the ports 30, 32 of the case. Auxiliary liquid chamber 34
．． 36 is preferably formed using a hollow hole provided in the piston 12, as shown in the figure.

The holes 35 and 37 are located at different positions in the circumferential direction, and have a phase difference in the circumferential direction.

Valve 3 opens and closes ports 26 and 28 of case 16, respectively.
8.40 is located on the lower side and upper side of the case 16, and the valve 4 that gently opens and closes the ports 30 and 32 of the case 18.
2.44 are arranged on the lower and upper sides of the case 18. These valves are formed by leaf springs, and the spring constant of each can be determined in consideration of the flow of liquid.

Spacer 46, valve 40, case 1 on piston rod 14
6. Insert the valve 3B, the piston 12 with the O-ring 48 attached, the valve 44, the case 18, the valve 42, and the spacer 50 in this order, and screw the nut 52 into the end of the piston rod 14 to complete the assembly.

A rotary valve 60 is disposed in the passage 22 of the piston rod 14 and switches the direction of liquid flow between the two liquid chambers A, B. The rotary valve 60 is rotated by an actuator 62, such as a solenoid valve known per se, installed in the space 24.

The rotary valve 60 shown in FIG. 2 includes a flange portion 61a and a shaft portion 61b that is integral with the flange portion 61a and has a circular cross section.
Three passages 64, 66, and 68 are provided in the shaft portion 61b by cutting out the shaft portion at intervals of 120° in the circumferential direction.

In the illustrated embodiment, the passage 64 communicates the passage portion 23a of the piston rod 14 with the hole 35 of the auxiliary liquid chamber 34 and the hole 37 of the auxiliary liquid chamber 36, and the passage 66 communicates with the hole 35 of the auxiliary liquid chamber 34 and the passage It communicates with the portion 23b. And passage 68
The hole 35 of the auxiliary liquid chamber 34 and the hole 37 of the auxiliary liquid chamber 36 are communicated with each other. Further, the passage 64 and the passage 66 may work together. In this case, the passage 64 communicates the passage portion 23a with the hole 37 of the auxiliary liquid chamber 36, and the passage 66 communicates with the hole 37 of the auxiliary liquid chamber 34. and the passage portion 23b are communicated with each other. Furthermore, the passage 66 is located in the auxiliary liquid chamber 3 due to its rotational position.
4 hole 35 and auxiliary liquid chamber 36 hole 37 and passage portion 23
b.

As shown in FIG. 3, the passage 64 of the rotary valve 60 is connected to the passage portion 23a, the hole 35 of the auxiliary liquid chamber 34, and the auxiliary liquid chamber 3.
6 (a), piston rod 1
In the extension stroke of 4, the valve 38 does not open because no differential pressure is generated between the upper and lower sides of the valve 38. Therefore, the liquid in the liquid chamber A above 5 passes from the passage portion 23a through the passage 64 and the hole 37 to the auxiliary liquid chamber 3.
6, and then the valve 42 is pushed open from the port 30 to flow into the liquid chamber B as shown by the arrow D1.

During the contraction stroke of the piston rod 14, there is no differential pressure between the upper and lower sides of the valve 40, so the valve 40 does not open.
The liquid in the liquid chamber B passes through the port 32, pushes open the valve 44, enters the auxiliary liquid chamber 36, and then flows to the liquid chamber A through the hole 37, the passage 64, and the passage portion 23a as shown by arrow D2.

When the passage 64 of the rotary valve 60 communicates between the passage section 23a and the hole 37, and the passage 66 communicates between the hole 35 and the passage section 23b (b), in the extension stroke of the piston rod,
The liquid chamber A passes through the passage portion 23a, the passage 64, and the hole 37 to reach the auxiliary liquid chamber 36, and then the valve 42 is pushed open from the port 30 and flows toward the liquid chamber B. 38 is pushed open and enters the auxiliary liquid chamber 34, after which a flow D3 from the passage 66 to the passage portion 23b and the liquid chamber B is generated. During the retraction stroke of the piston rod, the piston rod passes through the port 32 from the liquid chamber B, pushes open the valve 44 and enters the auxiliary liquid chamber 36, and then enters the hole 37, the passage 64, and the passage part 23.
Out of the flow D2 directed to the liquid chamber A through a, the flow D2 enters the auxiliary liquid chamber 34 from the liquid chamber B through the passage section 23b, the passage 66, and the hole 35, and then the valve 40 is pushed open from the port 28 to open the liquid chamber A.
A flow D4 directed toward is generated.

When the passage 66 of the rotary valve 60 communicates the passage portion 23b with the hole 35 of the auxiliary liquid chamber 34 and the hole 37 of the auxiliary liquid chamber 36 (C), in the extension stroke of the piston rod 14, there is a difference between the upper and lower sides of the valve 42. Since the valve 42 does not open because no pressure is generated, the liquid in the liquid chamber A pushes open the valve 38 from the port 26 and enters the auxiliary liquid chamber 34, and then flows through the hole 35, the passage 66,
The liquid flows through the passage portion 23b toward the liquid chamber B as indicated by D3. In the contraction stroke of the piston rod, the valve 4
Since the valve 44 does not open because there is no pressure difference between the upper and lower sides of the valve 4, the liquid in the liquid chamber B flows through the passage portion 23b, the passage 66, and the hole 3.
5 and enters the auxiliary liquid chamber 34, then pushes open the valve 40 from the port 28 and flows toward the liquid chamber A as shown in D4.

When the passage 68 of the rotary valve 60 or the hole 35 of the auxiliary liquid chamber 34 and the hole 37 of the auxiliary liquid chamber 36 communicate with each other (d), during the extension stroke of the piston rod, the liquid in the liquid chamber A flows from the port 26 to the valve. 38 to enter the auxiliary liquid chamber 34, and then pass through the hole 35, passage 68, and hole 37 to reach the auxiliary liquid chamber 36,
Push open the valve 42 from the port 30 and direct it to the liquid chamber B.
It flows like 5. Then, during the contraction stroke of the piston rod, the liquid in the liquid chamber B pushes open the valve 44 from the port 32 and enters the auxiliary liquid chamber 36, and then enters the hole 37, the passage 68,
The liquid passes through the hole 35 and reaches the auxiliary liquid chamber 34, then pushes open the valve 40 from the port 28 and flows toward the liquid chamber A as shown in D6.

If the flow pressure characteristics due to the valves 38.40 associated with the upper case 16 are made different from the flow pressure characteristics due to the valves 42.44 associated with the lower case 18, the damping force velocity characteristics shown in FIG. 4 can be obtained. It will be done.

A% d in Fig. 4 corresponds to states a and Nd in Fig. 3, respectively, or in a low piston speed range, the damping force is reduced by an orifice (not shown) provided in association with each port. The diagram is shown assuming that this has occurred.

In FIG. 4, a is a characteristic due to the port and valve of the lower case 18, and b is a characteristic due to the port and valve of the lower case 18 in addition to the characteristic due to the port and valve of the upper case 16, Since the liquids are flowing in parallel and the flow rate is increased, low damping force can be obtained. C is due to the ports and valves in the upper case 16. In addition to the characteristics of the ports and valves in the upper case 16, d is due to the characteristics of the ports and valves in the lower case 18, and the liquid is flowing in series and the differential pressure is high. High damping force can be obtained.

According to the rotary valve of the embodiment, depending on its rotational position, 4
Different types of damping force characteristics can be selected. The damping force characteristic in this case is approximately linear since the damping force is obtained by the valve associated with each port, and a sufficient damping force switching width can be obtained over the entire range of piston speed.

In the above embodiment, the valve is made of a leaf spring, and is operated only by the spring force. Alternatively, the valve may be formed of a leaf spring and the spring force of a coil spring may be added to increase the relief pressure of the valve.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the main parts of a shock absorber with variable damping force, Figure 2 is a perspective view of the rotary valve, and Figure 3 is a z.
d shows the flow at four different rotational positions of the rotary valve; the upper side shows a cross-sectional view of the vicinity of the piston, and the lower side shows a schematic bottom view of the rotary valve in the passage of the piston rod and the hole in the auxiliary liquid chamber. 1. FIG. 4 is a damping force speed characteristic diagram obtained in the state shown in FIG. 3. 10 cylinder, 12: piston, piston rod, 16, : case, double passage, 26. 28. 30, : Port, 34, : Auxiliary liquid chamber, 38. 40. 42, valve, rotary valve.

Claims (1)

[Claims] a cylinder, movably disposed within the cylinder;
A piston that partitions the inside of a cylinder into two liquid chambers, a piston rod that is connected to the piston and has a passage that communicates the two liquid chambers, and two cases that are arranged one above the other with the piston in between. and each case has a port through which liquid can flow when the piston rod is extended and a port through which liquid can flow when the piston rod is contracted;
and two cases that together with the piston define an auxiliary liquid chamber that communicates with the passage of the piston rod and the port of the case, a valve for opening and closing each port of each case, and a passage of the piston rod. A shock absorber having a variable damping force, the damping force being variable, the shock absorber comprising: a rotary valve that is disposed in the liquid chamber and switches the direction of liquid flow between the two liquid chambers; and an actuator that operates the rotary valve.