JPH10141417A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of keeping a value of drag generated at a constant value and providing nearly ideal energy absorption characteristics. SOLUTION: In a shock absorber 1, an orifice control mechanism provided with an orifice valve 23 which adjusts an opening area of an orifice 9, a distortion gage 24 which is arranged at a position where it receives the pressure of viscous liquid discharged from the orifice 9 and measures a distortion amount in accordance with pressure of the viscous liquid, and a piezo element 25 which is driven and controlled based on a voltage value which corresponds to the distortion amount measured by the distortion gage 24, expands, shrinks and deforms, and controls the orifice valve 23 due to its expansion, shrinkage, and deformation is provided. By controlling an opening area of the orifice 9 in accordance with pressure generated when an object collides against the shock absorber 1, namely, a value of drag generated, it is possible to absorb collision energy at a constant value of drag, even if collision conditions are changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorber used to absorb an impact at the time of a collision of an object, and more particularly to a shock absorber capable of keeping a generated drag value constant in response to a change in a collision condition. About.

[0002]

2. Description of the Related Art Industrial shocks conventionally applied to stoppers for objects such as conveyor line stoppers, robot arm stoppers, cylinder stoppers, and the like, used to absorb the impact of collision of these objects. Absorbers are known.

[0003] In this type of shock absorber utilizing the flow resistance of a viscous liquid, a substantially cylindrical cylinder accommodating the viscous liquid is partitioned into a liquid chamber and an accumulator chamber along the axial direction thereof. A partition member having an orifice for passing viscous liquid and a piston slidably mounted in the liquid chamber in the cylinder, and a partition formed on the back side thereof by a check valve. And a piston formed with a viscous liquid flow hole that allows only the flow of the viscous liquid from the chamber to the chamber partitioned to the front side of the piston.

[0004]

However, the conventional shock absorbers described above have the following problems. In other words, the shock absorbing efficiency of the shock absorber is constant, and therefore, when the absorbed energy is constant and the collision speed of the object changes, it cannot cope with this. For example, with a single shock absorber, when the object collides at a higher speed, the generated drag value becomes extremely high and the shock is large, and when the object collides at a lower speed, the collision object cannot be decelerated. Occurs greatly.

There is also a relief valve mechanism in which a valve for varying the opening area of an orifice is controlled by a spring in response to a change in pressure inside the shock absorber. However, since the followability of the spring is poor, valve control is also difficult. Poor follow-up performance, such as repeated opening and closing of the valve at high speeds, deviates considerably from ideal energy absorption (absorption characteristics in which the generated drag value is kept constant even when the collision speed changes). There was a problem that absorption characteristics could not be obtained.

The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to provide a shock absorber capable of maintaining a generated drag value at a constant value and exhibiting a more ideal energy absorption characteristic. And

[0007]

In order to achieve the above-mentioned object, a shock absorber according to the present invention comprises a liquid chamber and an accumulator chamber in a substantially cylindrical cylinder in which a viscous liquid is hermetically stored along an axial direction thereof. A partition member having an orifice for passing viscous liquid, a piston slidably loaded in the liquid chamber, one end protruding outside the cylinder, and the other end In a shock absorber having a piston rod connected to the piston and a return means for returning the piston and the piston rod, the shock absorber is disposed at a position receiving the pressure of the viscous liquid discharged from the orifice, A strain gauge that measures the amount of strain corresponding to the pressure of the viscous liquid, and is driven and expanded and contracted based on a voltage value corresponding to the amount of strain measured by the strain gauge. A piezo element to be formed, and an orifice valve disposed at a portion facing the orifice, holding the strain gauge and the piezo element, operating along the axial direction with the expansion and contraction deformation of the piezo element, An orifice control mechanism comprising a holding member for adjusting the opening area of the orifice by a valve is provided.

In this case, it is preferable to provide a plurality of the piezo elements and arrange them in series with each other. Further, by providing an end wall member that is screw-fitted to the rear end of the cylinder and abuts against the rear end of the piezo element, by adjusting the screw fitting position of the end wall member with the cylinder inner peripheral surface, The initial position of the piezo element may be adjusted to adjust the initial position of the orifice valve attached to the holding member.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on embodiments shown in the drawings. FIG. 1 is a sectional view of a shock absorber according to one embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part thereof. In these drawings, a shock absorber 1 includes a cylinder 2 in which a viscous liquid is hermetically stored, a partition member 3, and a piston 4
, A piston rod 5 and a spring 6.

The cylinder 2 is formed in a substantially cylindrical shape.
It is composed of a cylindrical member 2A whose both ends are open, and end wall members 2B and 2C which respectively close the open ends of the cylindrical member 2A. One end wall member 2B is screw-fitted to the inner peripheral surface of the open end portion on the rear end side of the cylindrical member 2A, and the other end wall member 2C is fitted to the inner peripheral surface of the open end portion on the distal end side of the cylindrical member 2A. Then, it is pressed down and fixed by the fixing member 2D screwed to the inner peripheral surface of the open end.

The partition member 3 is disposed so as to partition the inside of the cylinder 2 along its axial direction into a liquid chamber 7 and an accumulator chamber 8, and an orifice 9 for passing viscous liquid is formed along its central axis. Have been. Further, the end wall member 2
C and the partition member 3 are connected at a predetermined distance by a cylindrical member 10 whose both ends are fitted to the respective outer peripheral surfaces. A viscous liquid flow passage 11 is formed between the outer peripheral surface of the cylindrical member 10 and the inner peripheral surface of the cylinder 2. The liquid chamber 7 is formed inside the cylindrical member 10.

The piston 4 is slidably loaded in a liquid chamber 7 in the cylinder 2. The piston 4 has a check valve 12 disposed therein to form a viscous liquid flow hole that allows the viscous liquid to flow only when the piston 4 returns. That is, a partition is formed on the back side of the piston 4, and the accumulator chamber 8 and the viscous liquid flow passage 11 are formed.
A plurality of viscous liquid flow holes are formed, which allow only viscous liquid to flow from a chamber 13 (shown as a gap in the figure) communicating with the chamber 4 to a chamber 14 partitioned on the front side of the piston 4.

The piston 4 has a first disk member 15 integrally formed with the piston rod 5 and a second disk member 17 fixedly attached to a rod portion 16 integrally formed with the member 15. Consists of In the first disk member 15,
A plurality of through holes 18 are formed, and the check valve 12 is attached to the through holes 18. Further, a plurality of through holes 19 are formed in the second disk member 17, and in the present embodiment, the through holes 18 and 19 constitute the viscous liquid flow hole. The piston 4 may have any structure as long as it allows a large amount of viscous liquid to flow only when the piston 4 returns via the viscous liquid flow hole. Needless to say, the mounting method, the formation position and number of the through holes, the structure and the mounting method of the check valve, and the like are not limited to those shown in the drawings.

The end wall member 2C has a viscous liquid flow hole so as to communicate with one chamber 13 of the liquid chamber 7 and the viscous liquid flow passage 11 between the cylindrical member 10 and the cylinder 2. A functioning communication hole 20 is formed.

A spring 6 is interposed between the partition member 3 and the piston 4 to urge the two in a separating direction. The spring 6 functions as a return means for the piston 4 and the piston rod 5, but the return means is not limited to the case where the spring 6 is provided in the cylinder 2 as described above, but may be provided outside the cylinder 2 as well. It may be configured to be disposed around the protruding piston rod 5. Also,
It is also possible to adopt a configuration in which compressed air is supplied to the piston 4 and returned without using a spring.

On the other hand, between the partition member 3 and the end wall member 2B in the cylinder 2, a cylindrical member 21 forming the accumulator chamber 8 is screwed and fixedly mounted on the inner peripheral surface of the cylinder 2. In this case, an annular groove 21A is formed on the outer peripheral surface of a substantially intermediate portion in the axial direction of the cylindrical member 21, and the accumulator chamber 8 is formed between the inner surface of the groove 21A and the inner peripheral surface of the cylinder 2. The accumulator chamber 8 communicates with the viscous liquid flow passage 11 via a gap 22 formed between the outer peripheral surface of the cylindrical member 21 and the inner peripheral surface of the cylinder 2.

The shock absorber 1 having the above configuration includes:
An orifice valve 23 that adjusts the opening area of the orifice 9 formed in the partition member 3 and a position that receives the pressure of the viscous liquid discharged from the orifice 9 and measures the amount of distortion according to the viscous liquid pressure. A strain gauge 24 and a piezoelectric element (laminated piezoelectric element) 25 that is driven and controlled to expand and contract based on a voltage value corresponding to the amount of strain measured by the strain gauge 24 and controls the orifice valve 23 by the expansion and contraction.
And an orifice control mechanism configured to include:

The configuration of the orifice control mechanism will be described in detail. The piezo element 25 is disposed inside a cylindrical holding member 26 slidably provided inside the cylindrical member 21 for forming the accumulator. In the present embodiment, a plurality of piezo elements 25 are provided, and are each arranged in series inside the holding member 26. Each piezo element 2
Although the displacement of each element is small, a large displacement can be obtained as a whole by arranging a plurality of piezo elements 25 in series.

A flange 26A is formed at the rear end of the holding member 26, and a spring 27 is interposed between the flange 26A and the rear end of the cylindrical member 21 for forming the accumulator. Is done. This spring 27
Thereby, the holding member 26 is held at a predetermined position in the cylindrical member 21 and the orifice valve 23 is held at a predetermined initial position. In this case, the initial slide position of the piezo element 25 and the holding member 26 can be adjusted by adjusting the screw fitting position of the end wall member 2B abutting on the rear end of the piezo element 25 with the inner peripheral surface of the cylinder 2. The initial position of the orifice valve 23 can be easily adjusted.

A recess 26B is formed at the tip of the holding member 26 which faces the orifice 9, and an orifice valve 23 is fixed to the tip of the holding member 26 so as to close the recess 26B. Have been. The strain gauge 24 is provided in the recess 26 </ b> B, and the strain gauge 24 is fixed to the back surface of the orifice valve 23.

The control signal input wire 28 connected to the rear end of the piezo element 25 and the detection signal output wire 29 connected to the strain gauge 24 are connected to the through hole 2 of the end wall member 2B.
B is led out of the cylinder 2 through b.

The circuit of the orifice control mechanism having such a configuration is configured as shown in FIG. That is, the detection signal (small voltage signal) output from the strain gauge 24 of the shock absorber 1 is input to the amplifier 30, the small voltage signal is amplified by the amplifier 30, and the amplified signal is converted into a control circuit (fuzzy circuit) 31. Is input to The control signal from the fuzzy circuit 31 is input to a power supply circuit 32, which supplies a control voltage to the piezo element 25.

Next, the shock absorber 1 having such a configuration will be described.
The operation of will be described. When an object collides with the piston rod 5 and the piston 4 is pressed, the piston 4 moves in the liquid chamber 7. At this time, since the through hole 18 is closed by the check valve 12 of the piston 4,
The viscous liquid in the chamber 14 is compressed, passes through the orifice 9, and flows into the chamber 13 behind the piston 4 via the viscous liquid flow passage 11 and the communication hole 20. A part of the viscous liquid corresponding to the volume expansion due to the intrusion of the piston rod 5 and the temperature change flows into the accumulator chamber 8 through the gap 22. The impact at the time of collision of the object is absorbed by the viscous resistance of the viscous liquid and the dynamic pressure resistance generated when the viscous liquid passes through the orifice 9.

When the piston 4 returns, the check valve 12 operates to open the through hole 18, so that the viscous liquid in the chamber 13 flows through the through hole 18 and the through hole 19 of the second disk member 17. While returning to the chamber 14, it also returns to the interior of the chamber 14 through the communication hole 20, the viscous liquid flow passage 11, and the orifice 9. Therefore, when the piston 4 returns, a large amount of the viscous liquid moves, so that the resistance due to the viscous liquid is small, and the piston 4 and the piston rod 5 quickly return to the original positions.

According to the present embodiment, when the piston 4 slides in the shock absorbing direction, the viscous liquid in the chamber 14 is compressed, and after passing through the orifice 9, the pressure of the viscous liquid is reduced. Applied to the strain gauge 24. When pressure is applied to the strain gauge 24, the strain gauge 24 outputs a voltage signal proportional to the applied pressure. The voltage signal is input to the amplifier 30 and amplified, and is input to the fuzzy circuit 31. From the fuzzy circuit 31, a control signal corresponding to the voltage signal is input to the power supply circuit 32, and the power supply circuit 3
2 supplies a drive voltage for controlling the piezo element 25, whereby the piezo element 25 performs a predetermined expansion / contraction operation. That is, the piezo element 25 is driven based on a voltage controlled in accordance with the pressure applied to the strain gauge 24, and expands and contracts by an amount corresponding to the pressure of the viscous liquid.

By controlling the amount of expansion and contraction of the piezo element 25, the holding member 26 moves forward and backward, and the orifice valve 23
Controls the opening area of the orifice 9. In this case, the response frequency of the piezo element 25 is fast, for example, 2
The opening area of the orifice 9 is controlled at intervals of about ms until the object collides with the piston rod 5 and stops. Therefore, as a result of controlling the opening area of the orifice 9 according to the pressure at the time when the object collides with the shock absorber 1, that is, the generated drag value, even if the collision condition changes, the collision energy is absorbed at a constant drag value. be able to.

[0027]

According to the shock absorber of the present invention, an orifice valve for adjusting an opening area of an orifice, a strain gauge for measuring a strain amount corresponding to a pressure of a viscous liquid discharged from the orifice, and a strain gauge are used. An orifice control mechanism includes a piezo element that is driven and controlled to expand and contract based on a voltage value corresponding to the amount of distortion and controls the orifice valve by the expansion and contraction. Therefore, even if the collision conditions change, the collision energy can be absorbed with a substantially constant drag value, and an energy absorption characteristic closer to the ideal one can be obtained as compared with the conventional one.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a shock absorber according to the present invention.

FIG. 2 is a partially enlarged sectional view of the shock absorber according to the first embodiment;

FIG. 3 is a schematic circuit diagram of an orifice control mechanism of the shock absorber according to the first embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shock absorber 2 Cylinder 3 Partition member 4 Piston 5 Piston rod 6 Spring 7 Liquid chamber 8 Accumulator chamber 9 Orifice 12 Check valve 23 Orifice valve 24 Strain gauge 25 Piezo element 30 Amplifier 31 Fuzzy circuit 32 Power supply circuit

Continuation of the front page (72) Inventor Norio Koharu 2-760 Hibarigaoka, Zama City, Kanagawa Prefecture (72) Inventor Ichi Kamikura 662-3-507 Nobamachi, Konan-ku, Yokohama, Kanagawa Prefecture

Claims (3)

[Claims] 1. An orifice for passing a viscous liquid is disposed so as to partition a substantially cylindrical cylinder in which a viscous liquid is hermetically stored into a liquid chamber and an accumulator chamber along an axial direction thereof. Partition member, a piston slidably loaded into the liquid chamber, a piston rod having one end protruding outside the cylinder and the other end connected to the piston, and a return operation of the piston and the piston rod. A strain gauge disposed at a position for receiving the pressure of the viscous liquid discharged from the orifice, and measuring a strain amount according to the viscous liquid pressure; A piezo element that is driven and controlled based on a voltage value corresponding to the amount of distortion measured by the above-described method and that expands and contracts, and an orifice valve is provided at a portion facing the orifice And a holding member that holds the strain gauge and the piezo element, operates in the axial direction with the expansion and contraction of the piezo element, and adjusts the opening area of the orifice by the orifice valve. Shock absorber characterized by having an orifice control mechanism. 2. The shock absorber according to claim 1, wherein a plurality of said piezo elements are provided and arranged in series with each other. 3. An end wall member, which is screw-fitted to the rear end of the cylinder and abuts on the rear end of the piezo element, adjusts the screw-fitting position of the end wall member with the cylinder inner peripheral surface. 3. The shock absorber according to claim 1, wherein the initial position of the piezo element is adjusted to adjust the initial position of the orifice valve attached to the holding member.