JPS6340675Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a hydraulic shock absorber suitable for use in preventing vibrations of vehicles, industrial equipment, etc.

Conventionally, oil dampers have been widely used as this type of hydraulic shock absorber. However, conventional oil dampers have a constant damping force that dampens vibrations, so although they have the function of damping vibrations at a specific resonance point, they have the opposite effect when it comes to vibrations that are outside the resonance point. The drawback was that it reduced the anti-vibration effect.

Therefore, this idea provides a hydraulic shock absorber that can always exhibit a sufficient vibration isolation effect against any type of vibration. It is designed to automatically change according to the vibration state of the object to be vibration-isolated.

An embodiment of this invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall structure of a hydraulic shock absorber according to this invention. In this figure, 1 is an object to be vibration-isolated, and a coil spring 3 and an oil damper 4 are inserted between the lower surface of the object to be vibration-isolated and the mounting base 2, and the upper surface of the object 1 to be vibration-isolated is inserted. A vibration sensor 5 is attached to detect a vibration state (for example, vibration frequency). The oil damper 4 is provided with a control mechanism 4a that controls the damping force characteristics of the oil damper 4. This control mechanism 4a controls the damping force characteristics of the oil damper 4 based on the air pressure supplied to the air supply port, and has a pressure sensor that detects the air pressure supplied to the air supply port. The output of is supplied to the control section 6. The control unit 6 creates a control signal S based on the output of the vibration sensor 5 and the output of the pressure sensor, and outputs it to the pneumatic servo valve 7. The servo valve 7 controls the air pressure corresponding to the signal S to the control mechanism 4.
Supplied to the air supply port a.

Next, FIGS. 2A and 2B are a plan sectional view and a front view showing the structure of the servo valve 7, respectively. In these figures, reference numeral 9 is a servo valve main body, and this main body 9
A fluid chamber 10 penetrating in the front-back direction is formed in the center of the body. This fluid chamber 10 includes a fluid chamber 12
and cylindrical fluid chambers 13 to 15, the front surface of which is separated from the outside air by a diaphragm membrane 16, and a cap 17 attached to the rear surface. Further, the fluid chamber 12 is connected to the diaphragm membrane 1
8 to the front fluid chamber 12a and the rear fluid chamber 12b.
It is divided into two parts. The air supply port 20 to which compressed air is supplied is communicated with the fluid chambers 14 and 12a, and the output port 21 is connected to the fluid chambers 13 and 12a.
5, and the exhaust port 22 is communicated with the fluid chamber 12b.

Next, numeral 24 is a nozzle part, and nozzle 2
5, a protruding portion 26 and a sliding portion 27. The tip of the nozzle 25 communicates with the fluid chamber 12a, the diaphragm membrane 18 is attached to the protruding portion 26, and the sliding portion 27 is fitted in the fluid chamber 13 in an airtight manner. In addition, a flow path 2 that communicates the fluid chambers 12b and 13 is provided at the rear of the nozzle portion 24.
8 is formed.

Reference numeral 30 indicates a guide valve, and the guide valve 30 includes a first valve body 31, a sliding portion 32, and a second valve body 33. The first valve body 31 is adapted to be able to engage with the rear end opening of the flow path 28 in an airtight manner, the sliding portion 32 is fitted in the fluid chamber 14 in an airtight manner, and the second valve body The body 33 is adapted to engage the rear end opening of the fluid chamber 14 in an airtight manner.
Also, the second valve body 33 and the above-mentioned cap 17
A spring 34 is inserted between them, and the guide valve 30 is urged forward by this spring 34.

On the other hand, on the right side of the servo valve body 9 mentioned above,
A permanent magnet 39 and a coil 4 inserted into the permanent magnet 39 and supplied with a control signal S (FIG. 1).
0 and the locking member 4 attached to this coil 40
1 is provided, and the tip of the rod-shaped projection 41a of the locking member 41 is attached to the armature 43. armature 43
The right end portion thereof is attached to a shaft 44 so as to be rotatable in the front and rear direction, and the center portion thereof is locked to a locking plate 46 via a spring 45. A right end portion of a flapper 48 is attached to the left end portion of the armature 43, and the left end portion of the flapper 48 is arranged opposite to the tip of the nozzle 25 described above.

In the above configuration, when the control signal S is zero, the flapper 48 is at the reference position (the position shown in FIG. 2), and the rear end opening of the first valve body 31 and the flow path 28, the second valve body 33 and the rear end opening of the fluid chamber 14 are engaged with each other. Here, for example, when a positive control signal S is supplied to the coil 40, the coil 40 is attracted into the permanent magnet 39, so that the left end of the flapper 48 approaches the tip of the nozzle 25. As a result, the back pressure inside the fluid chamber 12a increases, and the nozzle part 24 and the guide valve 30
The second valve body 33 and the fluid chamber 14 are moved rearward against the repulsive force, and a gap between the second valve body 33 and the fluid chamber 14 is opened. As a result, the air supplied to the air supply port 20 is supplied to the control mechanism 4a (FIG. 1) through the fluid chambers 14, 15 and the output port 21, and the air pressure within the control mechanism 4a increases. On the other hand, when the negative control signal S is supplied to the coil 40, the flapper 48 moves away from the tip of the nozzle 25,
The back pressure in the fluid chamber 12a decreases. As a result, the back pressure in the fluid chamber 12a becomes lower than the pressure in the output port 21 and the flow path connected thereto, and the nozzle part 2
4 moves forward. As a result, the control mechanism 4a
The air inside the output port 21, flow path 28, fluid chamber 1
The air is exhausted from the exhaust port 22 through 2b, and the air pressure inside the control mechanism 4a decreases.

Next, FIG. 3 is a sectional view showing the structure of the oil damper 4 and the control mechanism 4a. As shown in this figure, the oil damper 4 has a double cylinder structure. That is, in the figure, numerals 51 and 52 are an outer cylinder and an inner cylinder, respectively, and a piston 5 is installed in the inner cylinder 52.
3 is slidably fitted, and this piston 53 connects the inside of the inner cylinder 52 with the first cylinder chamber 54 and the second cylinder chamber 54.
The cylinder chamber 55 is divided into two parts. Further, an oil reservoir 56 is formed between the outer cylinder 51 and the inner cylinder 52. Check valves 59 and 60 are provided on the piston 53 and the bottom plate 57 of the inner cylinder 52, respectively. 55 and the oil reservoir 56 are communicated with each other via a check valve 60. Further, the first cylinder chamber 54 is communicated with an oil reservoir 56 via an orifice 58. The tip of the piston rod 61 attached to the piston 53 and the bottom plate 62 of the outer cylinder 51 have attachment portions 63,
64 are formed, and these mounting portions 63 and 64 are respectively attached to the vibration-isolated object 1 and the mounting base 2 shown in FIG.
mounted on. Note that the reference numeral 65 is a cap. Further, the cross-sectional area of the piston rod 61 is 1/2 that of the piston 53.

A control mechanism 4a is attached to the side surface of the outer cylinder 51. The control mechanism 4a has an oil chamber 68 and an air chamber 69. The oil chamber 68 and the first cylinder chamber 54 communicate with each other through a flow path 70, and the oil chamber 68 and the oil reservoir 56 communicate with each other through a flow path 71. communicated through. A pressure regulating valve 73 is slidably and airtightly fitted into the wall surface 72 that partitions the oil chamber 68 and the air chamber 69, and the left end surface of the pressure regulating valve 73 is formed at the opening end of the flow path 70. The valve seat 75 can be brought into airtight contact with the valve seat 75. In addition, the pressure regulating valve 7
A large diameter portion 73a is formed at the right end of the air chamber 3, and a diaphragm membrane 77 is attached between this large diameter portion 73a and the peripheral wall of the air chamber 69.
7 divides the air chamber 69 into two, a first air chamber 69a and a second air chamber 69b. An air supply port 78 is provided on the wall surface of the first air chamber 69a, and a pressure sensor 79 for detecting the air pressure within the air chamber 69a is attached.
An exhaust port 80 is formed on the wall surface b. The output of the pressure sensor 79 is then supplied to the control section 6 shown in FIG. In addition, the pressure regulating valve 73 described above
A spring 81 is inserted between the large diameter portion 73a and the wall surface 72, and the valve body 73 is urged in the direction of the arrow X shown in the figure.

In the above configuration, when a predetermined air pressure is supplied to the first air chamber 69a through the air supply port 78, the pressure regulating valve 73 moves in the direction of the arrow Y shown in the figure against the biasing force of the spring 81, Its left end surface abuts against the valve seat 75. In this state, when the piston rod 61 moves slowly in the direction of arrow Y, the check valve 59 is closed and the check valve 60 is opened, and the oil in the first cylinder chamber 54 passes through the orifice 58 and enters the oil sump.
The oil in the oil reservoir 56 also flows into the second cylinder chamber 55 through the check valve 60. next,
When the piston rod 61 moves at high speed in the direction of arrow Y, the pressure of the oil in the first cylinder chamber 54 increases. Then, when the sum of the oil pressure in the first cylinder chamber 54 and the biasing force of the spring 81 exceeds the air pressure in the first air chamber 69a, the space between the pressure regulating valve 73 and the valve seat 75 opens, and the pressure in the first cylinder chamber The oil in 54 flows into the flow path 70
and flows into the oil reservoir 56 through the oil chamber 68. Further, the oil in the oil reservoir 56 flows into the second cylinder chamber 55 through the check valve 60. Here, the damping force against the vibration of the object 1 to be vibration-isolated is determined by the movement resistance of the oil, and therefore, the damping force can be changed by changing the air pressure in the first air chamber 69a. On the other hand, when the piston rod 61 moves in the direction of the arrow X, the check valves 59 and 60 are in the open state and
In the closed state, oil in the second cylinder chamber 55 flows into the first cylinder chamber 54 via the check valve 59, and the resistance to movement of the oil at this time acts as a damping force. In addition,
FIG. 4 shows the damping force characteristics of the oil damper 4. In this figure, the vertical axis is the damping force W, the horizontal axis is the moving speed V of the piston 53, and the curves _l1 to _l5 are damping force characteristic curves when the air pressure in the first air chamber 69a is changed. be. Note that the curve l ₁ is the case when the air pressure is the highest, and the curve l ₅ is the case when the air pressure is the lowest.

Next, the overall operation of the hydraulic shock absorber shown in FIGS. 1 to 3 will be described.

When the control unit 6 is powered on, the control unit 6
First, based on the output of the vibration sensor 5, the vibration-isolated object 1 is
detects the vibration state of the vibration state, and determines a command signal corresponding to the detected vibration state. Next, a control signal S corresponding to the difference between this command signal and the output of the pressure sensor 79 (FIG. 3) is output to the coil 40 of the servo valve 7. Now, for example, if a positive control signal S is output to the servo valve 7, the flapper 48 of the servo valve 7
approaches the nozzle 25, the gap between the valve body 33 and the fluid chamber 14 opens, the air supplied to the air supply port 20 is introduced into the air chamber 69a of the control mechanism 4a, and the pressure inside the air chamber 69a increases. Then, when the pressure within this air chamber 69a reaches a pressure corresponding to the command signal, and thereby the damping force of the oil damper 4 reaches a value corresponding to the command signal, the difference between the command signal and the output of the pressure sensor 79 increases. Therefore, the control signal S becomes zero, the flapper 48 returns to the reference position, and the space between the valve body 33 and the fluid chamber 14 is closed. On the other hand, if the pressure within the air chamber 69a is higher than the pressure corresponding to the command signal, a negative control signal S is output from the control section 6, and the flapper 48 moves the nozzle 25.
, thereby reducing the pressure within the air chamber 69a. When the pressure within the air chamber 69a reaches the pressure corresponding to the command signal, the control signal S becomes zero and the flapper 48 returns to the reference position. Next, when the vibration state of the vibration-isolated object 1 changes, the control unit 6
determines a command signal corresponding to the changed vibration state, and outputs a control signal S corresponding to the difference between this command signal and the pressure sensor 79 to the servo valve 7. As a result, the pressure within the air chamber 69a of the control mechanism 4a changes to a pressure corresponding to the command signal, and therefore the damping force of the oil damper 4 changes to a value corresponding to the command signal.

As explained above, according to this invention, the damping force characteristics of the oil damper attached to the object to be vibration-isolated are changed according to the vibration state of the object to be vibration-isolated, so that the vibration of the object to be vibration-isolated is A sufficient vibration damping effect can always be obtained even when conditions change in various ways. In addition, since this invention uses pneumatic control, it is easier to handle than hydraulic control, and the pressure in the air chamber that provides back pressure to the diaphragm provided in the pressure regulating valve is controlled by the valve. Since the bypass path is apparently outside the control loop, control is performed using a servo valve for pneumatic control, which is cheaper and simpler than a servo valve for hydraulic control. This has the effect of improving control responsiveness and reducing device costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of this invention; FIGS. 2A and 2B are a plan sectional view and a front view respectively showing the configuration of the servo valve 7 in FIG.
3 is a sectional view showing the structure of the oil damper 4 and control mechanism 4a in FIG. 1, and FIG. 4 is a diagram showing the damping force characteristics of the oil damper 4. 1...Object to be vibration-isolated, 4...Oil damper, 4a
... Control mechanism, 5 ... Vibration sensor, 6 ... Control unit, 7 ... Servo valve, 78 ... Air supply port, 79 ...
pressure sensor.

Claims (1)

[Scope of utility model registration request] In hydraulic shock absorbers that prevent vibrations of objects,
an oil damper having a double structure consisting of an inner cylinder and an outer cylinder, and configured by connecting two chambers defined by a piston reciprocably provided in the inner cylinder through a bypass passage; By energizing a pressure regulating valve provided in the middle of the bypass passage, which opens and closes the bypass passage, and which is displaced in the opening direction by fluid pressure in the bypass passage, and a diaphragm that operates the pressure regulation valve, the bypass passage is opened and closed. Based on signals from an air chamber that displaces a pressure regulating valve in the closing direction, a servo valve that adjusts the pressure of the air chamber, a pressure sensor that detects the pressure of the air chamber, and a vibration sensor that detects vibrations of the object. and a control unit that controls the servo valve based on the signal from the vibration sensor, and the control unit calculates a command signal corresponding to the pressure to be set in the air chamber based on the signal from the vibration sensor, and also calculates a command signal corresponding to the pressure to be set in the air chamber based on the signal from the vibration sensor. A hydraulic shock absorber characterized in that a control signal is supplied to the servo valve in order to make the difference between the supplied pressure signal and the command signal zero.