JPH0518431A - Double cylindrical vibration damper - Google Patents

Abstract

PURPOSE:To enhance the followup characteristics after motions by connecting one of the main oil chambers as partitioned with a piston moving within an inner cylinder slidingly with a reserver chamber via a detour, and furnishing this detour with a control valve which controls the damping force using a linear solenoid. CONSTITUTION:When a compressive force is applied to a damper 10, a piston 40 sinks to allow the working oil to flow from a main oil chamber 42 to another main oil chamber 44. At this time, the working oil flows out from the main oil chamber 44 to a passage 52b and reserver chamber 48 via a passage 74 associate with the intruding motion of a piston rod 30 into the main oil chamber 44. The flow path resistance this time is thus small, and the damping force is accordingly small. A selector valve 58 is, at this time, returned by a return spring so as to shut a detour 52. When a force acts on in the direction of elongation, a one-way valve 46 of the piston 40 is shut to cause boosting of the internal pressure of the main oil chamber 44, which boosts accordingly the internal pressure of an aux. oil chamber 60, and the working oil passes through the orifice 64 of the selector valve 58 to boost the internal pressure of another aux. oil chamber 62. Now a plunger 70 is depressed to decompress this aux. oil chamber 62, and the selector valve 58 opens the detour 52, and the damping force is controlled by a solenoid 68.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double cylinder attenuator having a reserve chamber between an inner cylinder and an outer cylinder.

[0002]

BACKGROUND OF THE INVENTION In vehicles such as automobiles and motorcycles, it is desirable to be able to change the damping force according to running conditions. Therefore, the applicant proposes one that detects the expansion / contraction amount (stroke) or expansion / contraction speed of the cushion unit in which the attenuator and the coil spring are integrated, and controls the opening / closing of the oil passage provided in the piston of the attenuator by the linear solenoid. (See, for example, Japanese Patent Application No. 1-1233).

The attenuator used here includes a piston that defines two main oil chambers in a cylinder, and a switching valve that is provided in the piston and defines first and second auxiliary oil chambers in the piston. And an orifice interposed between the first and second sub oil chambers to guide the hydraulic pressure of the high pressure side main oil chamber to the first sub oil chamber,
When the second auxiliary oil chamber pressure exceeds the pressure set by the linear solenoid, the switching valve is moved to open the oil passage between the two main oil chambers and control the damping force. According to this attenuator, it is possible to freely set the damping characteristics during expansion or contraction of the attenuator by changing the exciting current of the linear solenoid.

Since this attenuator was provided with a switching valve and a linear solenoid on the piston, there was a problem that the cord for electrical connection with the linear solenoid had to be passed through the piston rod, resulting in a complicated structure. Further, since the switching valve and the linear solenoid accommodated in the piston cannot be adjusted from the outside, the whole must be disassembled, and there is a problem that maintainability is poor.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-cylinder attenuator having a simple piston structure and good maintainability.

[0006]

According to the present invention, an object of the present invention is to provide a reserve chamber between an inner cylinder and an outer cylinder, and to provide a piston that slides in the inner cylinder and one direction provided on one end of the inner cylinder. In a double-cylinder attenuator that circulates hydraulic oil through an oil passage including the reserve chamber via a valve, connects one main oil chamber defined in the inner cylinder by the piston and the reserve chamber. This is achieved by a double-cylinder attenuator characterized by including a bypass and a control valve unit provided in the bypass and controlling a damping force by a linear solenoid.

[0007]

1 is a conceptual view showing an embodiment in which the present invention is applied to a strut type front suspension of an automobile, FIG. 2 is a sectional view of an attenuator thereof, and FIG. 3 is an explanatory view of its principle.

The strut type front suspension shown in FIG. 1 uses a strut 12 having a tubular attenuator 10 built-in as a part of a suspension link and is combined with a transverse link 14 and is called a so-called MacPherson type suspension. It is something that is said.

That is, the upper end of the strut 12 is rotatably supported by the suspension tower 16 of the body via a bearing 18, while the lower end of a knuckle 20 fixed to the lower end of the strut 12 is transposed via a ball shaft hand 22. It is connected to the berth link 14. The transverse link 14 is formed in a substantially A shape in a plan view, and two lower ends thereof are pivotally supported on the body side. Knuckle 2
A brake disc 24 and a front wheel 26 are attached to 0.

28 is a coil spring, and the strut 12
Is compressed between the upper spring seat 32 fixed to the piston rod 30 of the damper 10 and the lower spring seat 36 fixed to the outer cylinder 34 of the damper 10.

As shown in FIG. 2, the attenuator 10 has an outer cylinder 34.
An inner cylinder 38 is provided inside the piston, and a piston 40 that slides in the inner cylinder 38 is fixed to the lower end of the piston rod 30. As a result, the first and second main oil chambers 42, 4 are provided in the inner cylinder 38.
4 is defined. The piston 40 is provided with a first one-way valve 46 that allows an upward flow of hydraulic oil, that is, a flow from the first main oil chamber 42 to the second main oil chamber 44.

A reserve chamber 48 is formed between the inner cylinder 38 and the outer cylinder 34, and a gas such as low-pressure air is sealed in the upper portion of the reserve chamber 48. A second one-way valve 50 that allows the flow of hydraulic oil from the reserve chamber 48 to the first main oil chamber 42 is provided at the lower end of the inner cylinder 38.
The one-way valves 46 and 50 are reed valves.

Reference numeral 52 is a detour, which connects the upper portion of the second main oil chamber 44 and the lower portion of the reserve chamber 48. A control valve unit 54 for attaching a damping force to the hydraulic oil passing therethrough is attached to the bypass 52.

The control valve unit 54 includes a switching valve 58 that connects and disconnects the bypass 52 in the body 56. The first auxiliary oil chamber 60 is at the upper end of the switching valve 58, and the second auxiliary oil chamber 6 is at the lower end.
2 are formed respectively. Further, the switching valve 58 is provided with an orifice 64 interposed between the sub oil chambers 60 and 62. The first sub oil chamber 60 is provided with a second passage 66.
The oil pressure in the main oil chamber 44 is introduced.

Reference numeral 68 is a linear solenoid, and the tip end surface of the plunger 70 which moves linearly faces the second auxiliary oil chamber 62. The plunger 70 is biased upward by the excitation of the solenoid 68, and when the internal pressure of the second auxiliary oil chamber 62 becomes higher than the pressure of the plunger 70, the plunger 70 is pushed down,
The hydraulic oil in the second auxiliary oil chamber 62 escapes to the reserve chamber 48 via the passage 72.

The switching valve 58 has an annular notch portion 58a and a large diameter portion 58b adjacent to the notch portion 58a. Cutout 58a
A passage 52a communicating with the second main oil chamber 44 is exposed to the outside, and a passage 52 communicating with the reserve chamber 48 is provided on the outer peripheral surface of the large diameter portion 58b.
b is facing. The bypass 52 is formed by these passages 52a and 52b. Further, the upper portion of the second main oil chamber 44 communicates with a passage 52b communicating with the reserve chamber 42 side by a passage 74 having a small diameter.

[0017]

[Attenuator operation] When a force in the compression direction is applied to the attenuator 10, the piston 40 descends and the first main oil chamber 42 moves to the second
The hydraulic oil flows into the main oil chamber 44 of the. At this time, as the piston rod 30 enters the second main oil chamber 44, the working oil from the second main oil chamber 44 passes through the passage 74 and the passage 52b,
It flows into the reserve chamber 48. Therefore, the flow path resistance at this time is small and the damping force is small. At this time, the switching valve 58 is returned to the position shown in FIG. 2 where the bypass 52 is closed by a return spring (not shown).

When a force in the extension direction is applied to the attenuator 10, the one-way valve 46 of the piston 40 is closed, so the second main oil chamber 4
The internal pressure of 4 rises. Therefore, the internal pressure of the first sub oil chamber 60 rises, and further the internal pressure of the second sub oil chamber 62 also rises through the orifice 64 of the switching valve 58. When the internal pressure of the second auxiliary oil chamber 62 exceeds the pressure of the plunger 70, the plunger 70 is pushed down so that the working oil from the second auxiliary oil chamber 62 is reserved in the reserve chamber 4
Escape to 8. Therefore, the inside of the second auxiliary oil chamber 62 is depressurized, the switching valve 58 descends, and the bypass 52 is opened. During this time, the working oil passes through the orifice 64 and flows from the first sub oil chamber 60 to the second sub oil chamber 6
Because of the flow of the gas to No. 2, the switching valve 58 is kept open due to the pressure reducing effect of the orifice 64. Therefore, the damping force is controlled by the opening pressure of the plunger 70, that is, the exciting force of the solenoid 68.

[0019]

[Stroke Sensor] In FIG. 1, reference numeral 80 denotes a potentiometer, which may be, for example, a sliding resistance type whose electrical resistance changes depending on the amount of rotation of the lever 82. The potentiometer 80 is attached to the outer circumference of the outer cylinder 34 below the lower spring seat 36. Lever 8
The rotating end of 2 is connected to the upper spring seat 32 by a rod 84. Both ends of the rod 84 are connected by ball joints. Therefore, the stroke position p ₀ of the attenuator 10 can be detected by the resistance value of the potentiometer 80.

[0020]

[Controller] When the stroke position p ₀ is detected as described above, the position signal p is used as a low-pass filter (LPF).
It is input to the CPU 88 via 86. CPU88 is
First, the lever ratio correction means 90 corrects the ratio of the displacement amount of the front wheel 26 and the expansion / contraction amount of the attenuator 10, that is, the lever ratio, from the position signal p. The CPU 88 is speed detecting means 92.
The position signal P after this correction is time-differentiated to obtain the speed V of the piston 40. Further, the direction discriminating means 94 obtains the expansion / contraction direction from the positive / negative of this time derivative.

The duty calculation means 96 stores in advance the duty ratio of the exciting current of the linear solenoid 68 for generating the optimum damping force with respect to the speed V and the expansion / contraction direction in the form of a map. The signal d indicating the corresponding duty ratio is read from this map based on the direction. The pulse width control means (PWM) 98 outputs the pulse width control signal D based on the signal d of this duty ratio. This signal D is output from the CPU 88, and the integrating circuit 100 outputs a current command signal i whose voltage changes according to the duty ratio. The current control circuit 102 outputs the exciting current I of the linear solenoid 68 based on the signal i.

In the above-described embodiment, the potentiometer 80 is provided below the coil spring 28 and the rod 84 is arranged outside the coil spring 28. However, as shown by the phantom line in FIG. Potentiometer 80
A and the rod 84A may be arranged.

FIG. 4 is a diagram showing an embodiment applied to a cushion unit for a motorcycle. Here, attenuator 10
The lower bracket 34C fixed to the outer cylinder 34B of B is provided with a potentiometer 80B.
The lever 82B of 0B is connected to the upper spring seat 3 by the rod 84B.
Ligated to 2B. Note that, in this figure, the same parts as those in FIG. The control valve units 54, 54 in the present invention
B is not only the one directly fixed to the outer cylinder 34, 34B,
It may be separated from the outer cylinder.

[0024]

As described above, according to the present invention, a control valve unit is provided in a bypass line connecting one main oil chamber and a reserve chamber,
Since the damping force can be controlled by the linear solenoid, the piston can be made lightweight with a very simple structure, and its inertia can be reduced to improve the followability of the operation. Further, since the control valve unit is outside the outer cylinder, its maintainability is good.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment in which the present invention is applied to a front wheel suspension of an automobile.

FIG. 2 is a sectional view of the attenuator.

[Figure 3] Illustration of the principle

FIG. 4 is a diagram showing another embodiment.

[Explanation of symbols]

 10, 10B Attenuator 34, 34B Outer cylinder 38, 38B Inner cylinder 40 Piston 42, 44 Main oil chamber 46, 50 One-way valve 48 Reserve chamber 52 Detour 54, 54B Control valve unit 68 Linear solenoid

Claims (1)

Claims: 1. A reserve chamber is provided between an inner cylinder and an outer cylinder,
In a multi-cylinder attenuator that circulates hydraulic oil in an oil passage including the reserve chamber via a piston that slides in the inner cylinder and a one-way valve provided at one end of the inner cylinder,
A bypass circuit that connects the main oil chamber and the reserve chamber defined in the inner cylinder by the piston, and a control valve unit that is provided in the bypass circuit and controls the damping force by a linear solenoid. A characteristic double-tube attenuator.