JPS6337541Y2 - - Google Patents

Description

[Detailed description of the invention] Technical field The present invention is an improved anti-vibration table that can be used for mounting measuring instruments, precision instruments, etc., and can quickly and automatically adjust the height without causing hunting. The present invention relates to an air spring height control device.

Prior Art Fig. 1 is a partial schematic side view showing an example of a vibration isolation table on which the air spring height control valve according to the present invention is used, in which 1 is a mounting plate on which precision equipment is mounted;
is an air spring, 3 is an auxiliary air reservoir connected to the air spring 2, 4 is a probe fixed to the mounting plate 1, 5 is a compressed air supply pipe, 6 is a control valve, 7 is the control valve 6 and the auxiliary air A pipe that connects the reservoir 3. As is well known, precision equipment is mounted on the mounting plate 1, and in this case, the mounting plate is used to prevent external vibrations from being transmitted to the precision equipment. 1 is elastically supported by an air spring 2. Then,
In the above-mentioned vibration isolation table, there is a problem if the level of the mounting plate 1 fluctuates depending on the weight of the precision equipment mounted on the mounting plate 1. The probe 4 and the control valve 6 are provided to solve this problem. For example, when the weight of precision equipment is heavy, the level of the mounting plate 1 is lowered and the probe 4 is lowered accordingly. The level also decreases, but when the probe 4 is lowered, the supply valve of the control valve 6 operates and compressed air from a compressed air source (not shown) is supplied to the auxiliary air reservoir 3 through the pipe 5, control valve 6, and pipe 7, and the air is supplied to the auxiliary air reservoir 3. Increase the pressure within spring 2. In this way, when the pressure inside the air spring 2 increases, the mounting plate 1
rises, and the probe 4 rises accordingly. When the probe 4 reaches a predetermined level, the supply valve of the control valve 6 operates to stop the supply of air into the air spring 2, and the mounting plate 1 follows. precision equipment is maintained at its predetermined level. On the other hand, if the weight of the precision equipment mounted on the mounting plate 1 is light, the mounting plate 1 and the probe 4 will rise, the exhaust valve of the control valve 6 will open, and the air in the auxiliary air reservoir 3 will be discharged from the pipe 7. It is exhausted to the atmosphere through the exhaust valve of the control valve 6, and the air pressure in the air spring 2 is reduced. In this way, when the air pressure in the air spring 2 decreases, the mounting plate 1 descends, and the probe 4 also descends accordingly. When the probe 4 reaches a predetermined level, the exhaust valve of the control valve 6 is closed and the air is discharged. The discharge of the mounting plate 1 and therefore the precision equipment is maintained at its predetermined level.

FIG. 2 is a diagram showing an example of a conventional air spring height control device. As shown in the figure, a main body 12 has a lever or a swing plate 2 pivotally connected to its upper end with a pin 25.
6, and the swing plate 26 is always urged upward by a spring 27 so as to always engage the probe 4. A chamber 29 that accommodates the elevating body 28 (that is, a valve assembly) is provided inside the main body 12, and a port 30 bored in one side of the main body 12 communicates with the chamber 29 via a communication path 31. On the other hand, a port 32 formed on the other side of the main body portion 12 directly communicates with the chamber 29 . The air pipe 15 is connected to the port 30, and the air pipe 7 is connected to the port 32.
are now connected. Therefore, an air source (not shown) is connected to the port 30 via the air pipe 5, and an auxiliary air reservoir 3 is connected to the port 32 via the air pipe 7. The elevating body 28 housed in the chamber 29 is always urged upward by a spring 33, and is guided by a guide pin 34 protruding into the chamber 29 so that it can move vertically. It's getting old. A valve seat 35 for opening and closing the communication passage 31 is fixed to the elevating body 28, and the valve seat 35 and the communication passage 31 constitute a supply valve for supplying working air into the air spring 2. There is. The upper center of the elevating body 28 is a valve head 36 formed in a nozzle shape, and a passage 37 opening into the valve head 36 is provided. A seal member 38 is attached to the lower surface of the swing plate 26 as a valve seat for the valve head 36, and this seal member 38, the swing plate 26, and the valve head 36 serve as a valve seat for the valve head 36. It constitutes a discharge valve. Therefore, if a part of the mounting plate 1 now moves to a higher position than the equilibrium state shown in FIG. The passage 3 of the valve head 36 is pushed up.
7 is opened, the air in the air spring 2 enters the port 32 through the auxiliary air reservoir 4 and the air pipe 15 and is further discharged to the atmosphere through the passage 37 of the valve head 36. Therefore, the air spring 2 is pushed down, the mounting plate 1 is lowered, and the probe 9 is also lowered, so that the swing plate 26 is pushed down. As a result, the passage 37 of the valve head 36 is closed and the release of air from within the air spring 2 is stopped, so that the mounting plate no longer moves downward and stops at the equilibrium state shown in FIG. 2. On the other hand, when the mounting plate is displaced downward from the equilibrium state shown in FIG. 2 (when the mounted equipment is heavy), the swinging plate 26 is pushed down by the lowering of the probe 4, and the valve head 36 is pushed down. Since it is lowered, the valve seat 35, which is integrated with the elevating body 28, also moves downward. As a result, the communication path 31 is opened, the chamber 29 and the port 30 are communicated, compressed air is sent into the chamber 29 from the air source communicating with the port 30 via the air pipe 5, and furthermore, the air pipe 7 The air is fed into the air spring 2 through the air. For this reason, air spring 2
is pushed up, and the mounting plate 1 is lifted upward. Therefore, the probe 4 that is integrated with the mounting plate 1 rises, the swing plate 26 is also pushed up by the spring 27 and follows the probe 4, and the elevating body 28 is also pushed up by the spring 33 so that the valve seat 35 moves into the communication path. 31, close the second
The equilibrium state shown in the figure is reached.

In the above-mentioned vibration isolating table, if the supply and discharge passages 31 and 37 are made large, it is possible to quickly reach the vicinity of the equilibrium point, but on the other hand, hunting is likely to occur, resulting in Generally speaking, it takes time to reach an equilibrium state, and conversely, these supply and discharge passages 3
If 1,37 is made smaller, problems such as hunting will disappear, but on the other hand, it will take time to bring it near the equilibrium point, and in this case, as a result, it will take time to reach the equilibrium state. There were flaws. In particular, when hunting occurs, the movable parts of the level adjustment device operate very frequently, and as a result, the movable parts of the air spring height control device tend to wear out, and the life of the device is relatively short. There was a problem. In addition, if the valve parts were not worn uniformly, there was a problem that the levelness could not be maintained.

Purpose Therefore, the purpose of this invention is to provide an air spring height control device and an improved air spring height control device that does not cause hunting in the air spring and can quickly achieve horizontal equilibrium. Another object is to provide an improved anti-vibration table with a long service life.

Embodiment FIG. 3 is a cross-sectional view of an air spring height control device 6A for a vibration isolating table improved according to the present invention in an equilibrium state. and a first discharge valve 50 with a small flow rate made up of a sealing member 38 and a first supply valve 60 with a small flow rate made up of a communication passage 31 and a valve seat 35. second discharge valve 3
9, and a second supply valve 40 with a large flow rate arranged in parallel with the first supply valve 60. These first supply valve 60 and first discharge valve 50
As will be made clear from the following explanation, the opening is opened when the mounting plate 1 deviates within a predetermined range from the reference height position, and supplies and discharges working air to the pneumatic support device. The second supply valve 40 and the second discharge valve 39 are opened when the mounting plate is deflected beyond the predetermined range to supply and discharge working air to and from the pneumatic support device. In the illustrated example, the first discharge valve 50 and the first supply valve 60 have the same structure as those equipped in the conventional device shown in FIG.

As shown in FIG.
, a discharge port 42 communicating with the communication passage 41, a valve body 43 fixed to the rocking plate 26 and engaged with the tip of the discharge port 42, and a valve body 43 that is always directed toward the discharge port 42. It consists of a energized spring 44,
The second discharge valve 39 is opened when the mounting plate 1 rises above a predetermined range from the reference position, and serves to rapidly discharge the pressurized air in the air spring 2 into the atmosphere.

On the other hand, the second supply valve 40 provided in parallel with the first supply valve 60 is connected to the communication path 40 provided in parallel with the communication path 31.
5, a valve body 46 supported by the elevating body 28 to open and close the communication passage 45, and a spring 47 that always biases the valve body 46 toward the opening of the communication passage 45. The second supply valve 40 is opened when the mounting plate 1 deviates downward from the reference position by more than a predetermined range, and operates to increase the amount of operating air supplied to the air spring 2.

FIG. 4 shows the state of the air spring height control device 6A when the mounting plate is deviated to the upper limit position, but in this case, the probe 4 integrated with the mounting plate has also reached its own upper limit position. Since the rocking plate 26 is pressed against the probe 4 by the spring 27, the passage 37 of the valve head 36 is opened and the second discharge valve 39 is opened.
The passage in the outlet 42 is open. Therefore, the inside of the air spring includes air pipe 7, port 32, and chamber 2.
9, is opened to the atmosphere through the passage 37 of the valve head 36, the communication passage 41, and the discharge port 42, that is, through the large-flow discharge valve 39 and the small-flow discharge valve 50, so that the air inside the air spring 2 is is greatly reduced in pressure, and therefore the mounting plate 1 is rapidly lowered, and the probe 4 is also lowered at the same time, and the swing plate 26 is pushed down. When the mounting plate 1 is lowered to a predetermined level, as shown in FIG.
are fully engaged and the passageway of the outlet 42, ie, the high flow rate outlet valve 39, is completely closed, and therefore,
The flow path of the air released into the atmosphere from the air spring 2 is a passage 37 of the valve head 36, that is, a small flow discharge valve 50.
Since the downward speed of the air spring is also reduced, the downward speed of the rocking plate 26 and the mounting plate 1 is also reduced. However, the exhaust from the air spring 2 to the atmosphere still continues through the passage 37, so the mounting plate 1 slowly descends until the passage 37 is completely closed by the sealing member 38 of the rocking plate 26. do. When the passage 37 is completely closed by the seal member 38 to reach an equilibrium state (see FIG. 3), the mounting plate 1 stops lowering, and this equilibrium state is maintained. On the other hand, if the mounting plate 1 deviates significantly downward from the equilibrium state (if a heavy device is mounted on the mounting plate 1), the swing plate 26 will be greatly pushed down by the probe 4, and the The valve seat 35 of the first supply valve 60 with a small flow rate opens the communication passage 31, and the valve body 46 of the second supply valve 40 with a large flow rate also opens the communication passage 45. Therefore, working air is rapidly supplied from the air source into the chamber 29 through the port 30 and the communication passages 31 and 45, and as a result, the air spring 2 is rapidly filled with working air and the mounting plate is also rapidly filled. begins to rise. As the mounting plate rises, the probe 4 also rises, so the elevating body 28 also rises due to the action of the spring 33, and at the same time, the swing plate 26 also rises following the probe 4 due to the action of the spring 27. In this process, when the mounting plate 1 rises to a predetermined height, the valve body 46 is pressed against the opening of the communication passage 45 and the large flow communication passage 45 is closed, but at that time, the small flow communication passage 31 is still open. Since the air spring 2 is closed, the supply of working air to the air spring 2 continues. However, since the communication passage 31 has a considerably smaller cross-sectional area than the communication passage 45, the amount of air supplied to the air spring 2 after this point is reduced, so that the mounting plate 1 rises at a slower speed. At the end of the upward movement, the valve seat 35 closes the communication passage 31, and the supply of working air to the air spring 2 is cut off.
Therefore, the mounting plate reaches the predetermined reference height position at a very slow speed.

Effects As is clear from the above explanation, according to the present invention, when the air pressure is far from the equilibrium state, the air pressure is rapidly increased or decreased through the large flow supply/discharge valve, and when the equilibrium state is approached, Since the equilibrium state is achieved slowly through the small flow rate supply/discharge valve, there is very little risk of overshoot due to excessive control operation.Therefore, there is no risk of hunting, and equilibrium is quickly achieved. can be in a state. Furthermore, since hunting does not occur, there is less wear on the air spring and the movable parts of the air spring height control device, resulting in a significant improvement in durability and, at the same time, the ability to maintain levelness with high precision.

[Brief explanation of the drawing]

Fig. 1 is a partial schematic side view showing an example of a vibration isolating table to which an air spring height control device is applied, and Fig. 2 is a conventional air spring height control device equipped on the vibration isolating table shown in Fig. 1. A schematic longitudinal sectional view of the device; FIG. 3 is a sectional view of the air spring height control device according to the present invention in an equilibrium state;
4 and 5 are cross-sectional views of the apparatus of FIG. 3 in various states. DESCRIPTION OF SYMBOLS 1... Mounting plate, 2... Air spring, 3... Auxiliary air reservoir, 4... Probe, 6A... Air spring height control device, 26... Rocking plate, 28... Lifting body, 3
0, 32... Port, 35... Valve seat, 36... Valve head, 31, 41, 45... Communication passage, 39... Second discharge valve, 40... Second supply valve, 50... First Discharge valve, 60...first supply valve.

Claims (1)

[Scope of utility model registration request] A mounting plate for placing an object such as a device, an air spring support device elastically supporting the mounting plate, and supplying compressed air into the air spring by detecting a level change of the mounting plate. or a control valve for discharging the air in the air spring to maintain a constant level of the mounting plate, the control valve comprising a valve body;
2 which are rotatably pivotally connected to the valve body and which are displaced in accordance with level fluctuations of the mounting plate and which have different amounts of displacement;
a rocking plate having first and second valve seats for the discharge port at two positions, and a first valve seat for the discharge port that is disposed through the valve body and has the larger displacement amount at the tip end thereof; a valve stem having a first discharge port facing the valve body; and a spring member disposed in a chamber formed in the valve body to press the valve stem toward the rocking plate; The valve stem is configured such that the discharge port communicates with the air spring chamber through the air passage bored through the valve stem and the chamber in the valve body, and a first and second air spring chamber integral with the valve stem in the chamber of the valve body. a second inlet valve seat, and the valve body has first and second inlet valve seats each facing the first and second inlet valve seats of the valve stem in the chamber and communicating with an air pressure source. first and second valve heads having exhaust passages, the second valve head opens a second flow path of the valve stem when the amount of displacement of the valve stem is large, and further,
The chamber in the valve body is placed in the second chamber with the smaller displacement amount.
a second discharge port opening opposite to a valve seat for the discharge port, and an air supply passage and an exhaust passage formed by the second valve seat and the valve head are connected to the first discharge port. An air spring height control device characterized in that the air spring height control device is formed into a large flow passage with respect to an air supply passage and an exhaust passage formed by a valve seat and a valve head.