JP2779806B2 - Automatic pressure regulator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic pressure regulator provided for adjusting the internal pressure of an air chamber of an air spring device.

(Technical Background of the Invention and its Problems) Devices that dislike vibration, such as an optical device such as an electron microscope and a device that requires precise driving, are used by being mounted on a vibration isolation table having a vibration absorbing function.

The air spring type anti-vibration table responds to such demands.The roof is supported by several air spring devices, the internal pressure of this air chamber is adjusted using a compressor, etc., and a constant attitude is maintained. Then, a predetermined vibration isolation effect is obtained. In particular, when the roof is supported by several air spring devices, it is necessary to adjust the support height, that is, the level, and an automatic pressure regulator is used for this purpose.

FIG. 6 shows a longitudinal sectional view of a conventional automatic pressure regulator.

This device includes an upper valve stem 2 disposed so as to penetrate the body case 1 from above to the inside, and a lower valve stem 3 disposed at a lower end thereof. A pressure adjusting chamber 6 is formed between these valve stems and the inner wall of the main body case 1.

The pressure regulating chamber 6 is divided into a first chamber 4 formed so as to surround the upper valve stem 2 and a second chamber 5 formed so as to surround the lower valve stem 3. The first chamber 4 has an air spring connection hole 10 connected to the air chamber 8. In addition, this air chamber 8
Is provided in the air spring device, and a roof (not shown) arranged above the figure is supported by the air spring device. Also, the upper valve stem 2 is configured to move up and down in the direction of arrow 11 following the up and down movement of the roof. On the other hand, the second chamber 5 is provided with a compressed air suction hole 9 to which a pipe from the compressor 7 for supplying compressed air is connected.

An exhaust hole 12 is provided at the center of the upper valve stem 2, and a flange 13 is provided on the outer periphery thereof. The flange 13 is configured to be urged in the upward direction by a spring 14. . An annular poppet portion 16 is provided on the upper surface of the lower valve stem 3, and a spring 18 is disposed below the flange 17 for supporting the same. The spring 18 moves the lower valve stem 3 upward in the drawing. We are pushing to push up. With this force, the poppet 16
Is pressed against the lower end 19 of the upper valve stem 2 and the rib 20 protruding from the inner wall of the main body case 1, and
And the second room 5 is hermetically sealed. An O-ring 21 is inserted between the upper valve stem 2 and the main body case 1 to hermetically seal the first chamber 4 from the outside.

First, when the roof rises above the reference position, the upper valve stem 2 rises following this, and the lower end 19 rises up from the poppet part 16 and the air pressure regulator Air is allowed to be exhausted from the chamber 8 through a path indicated by a chain line 23. When the air is discharged from the air chamber 8 to the outside by following such a path, the internal pressure of the air chamber 8 is reduced, whereby the force for supporting the roof is reduced and the roof is lowered.

On the other hand, when the roof falls from the reference position, the upper valve stem 2 descends following the downward movement. In this case, since the upper valve stem 2 pushes down the lower valve stem 3, the rib 20 protruding from the main body case 1 and the poppet portion 16 are separated, and the compressed air flows from the compressor 7 through the compressed air inflow hole 9 and along the dashed line 24. Flows into the first room 4. When the internal pressure of the first chamber 4 increases in this way, the internal pressure of the air chamber 8 communicating with the first chamber increases, and the air spring device pushes up the roof. As a result, the roof rises toward the reference position.

With the above operation, the automatic pressure regulator operates to adjust the internal pressure of the air chamber 8 of the air spring device and hold the roof at a predetermined reference position.

Meanwhile, in the conventional automatic pressure regulator as shown in FIG. 6, the upper valve stem 2 and the lower valve stem 3 are urged upward by springs 14 and 18, respectively. It will not operate unless a force that overcomes the combined force is applied. Therefore, it is necessary to carefully select the adjustment of the elastic force of each spring while taking the mutual operating conditions into consideration.

Further, in the above-described structure, the upper valve stem 2 and the lower valve stem 3 can individually move up and down, and so-called chattering may occur. If these cause chattering, a hunting phenomenon in which the roof rises or descends while vibrating easily occurs. This has an adverse effect on the stable floating and stable lowering of the vibration isolation table. In addition, since the amount of air flowing into or out of the pressure adjusting chamber 6 is substantially constant irrespective of the amount of displacement of the roof from the reference position, hunting is also likely to occur. There was a problem.

In addition, when initially in a stable state, the upper valve stem 2
The lower end 19 of the is stationary with the poppet part 16 biting into it. Here, when the upper valve stem 2 rises, the air is discharged in the direction of arrow 23 only after the lower end 19 of the upper valve stem 2 separates from the poppet portion 16, and when the upper valve stem 2 descends again. At the moment when the lower end 19 contacts the poppet portion 16, the discharge of air is stopped. If the internal pressure of the first chamber 4 does not further decrease, the lower end 19 of the upper valve stem 2 will not bite into the poppet portion 16 this time. That is, there is a problem that the bite into the poppet portion 16 that has occurred earlier remains as hysteresis, and the restoring property is poor.

In order to solve such a problem, there has been conventionally proposed an improved valve stem in which the upper valve stem 2 and the lower valve stem 3 are integrally moved up and down. On the correlation with the displacement of
Sufficient properties have not yet been obtained.

(Object of the Invention) The present invention has been made in view of the above points, and an object of the present invention is to provide an automatic pressure regulator which does not easily generate hunting and has excellent air flow characteristics.

(Summary of the Invention) The automatic pressure regulator of the present invention has a pressure regulating chamber which is communicated with an air chamber of an air spring device supporting a roof and adjusts the pressure of the air chamber. An air spring connection hole connected to the air chamber, a compressed air suction hole connected to a compressor that supplies compressed air, and an end that penetrates the outer wall of the pressure adjustment chamber and connects one end to the pressure adjustment chamber. A valve stem extending to the outside, an exhaust hole formed in a shaft portion of the valve stem, one end of which is opened inside the pressure adjustment chamber and the other end is formed outside of the pressure adjustment chamber, A cantilever for detecting the elevation of the roof, and an exhaust valve for opening and closing the other end of the exhaust hole by elevating the cantilever, wherein the pressure adjustment chamber is open at one end of the air spring connection hole and one end of the exhaust hole. A first room to be A second chamber in which a compressed air suction hole is opened, and the valve stem is covered with a removable orifice at the other end of the exhaust hole, and only when the roof is lowered,
A poppet portion for opening a boundary between the first room and the second room is provided in accordance with the movement of the valve stem following the movement of the valve stem, and a poppet portion is provided for air flowing from the first room to the second room. The cross-sectional area of the flow path is selected such that when the poppet portion is in the open state, the lowering amount of the roof is small when the descending amount is small, and wide when the descending amount is large.

(Embodiment of the Invention) FIG. 1 is a longitudinal sectional view showing an embodiment of the automatic pressure regulator of the present invention.

In the figure, the main body case 31 of this device
A pressure adjustment chamber 36 similar to that described in the drawing is formed,
The pressure adjustment chamber 36 is composed of an upper half first chamber 34 and a lower half second chamber 35. Further, a valve stem 32 is provided which penetrates an upper outer wall of the pressure adjusting chamber 36 and has one end extending outside the pressure adjusting chamber 36.

The outer wall of the main body case 31 has a compressed air suction hole 37 connected to a pipe of the compressor 7 for supplying compressed air.
And an air spring connection hole 38 connected through a pipe to an air chamber 8 of an air spring device that supports a roof (not shown).

The air spring connection hole 38 opens toward the first room 34, and the compressed air suction hole 37 opens toward the second room 35.

On the other hand, above the main body case 31, there is provided a cantilever 42 which swings following the elevating movement of a roof (not shown),
Here, a force is applied by a pin 43 and a spring 44 to swing in the direction of the arrow 50 about the shaft 48. In the shaft portion of the valve stem 32, an exhaust hole 45 having one end opened in the first chamber 34 and the other end opened outside the pressure adjustment chamber 36 is provided. An orifice 46 is detachably attached to the upper end of the exhaust hole 45 by screwing or the like. An exhaust valve 47 is provided between the cantilever 42 and the orifice 46 to open and close the orifice 46.

Further, a flange 40 is provided at a portion of the valve stem 32 housed in the second chamber 35, and a poppet 41 made of an elastic body is provided around the flange 40. And valve stem 32
Is biased upward by a spring 52 disposed at its lower end, and the poppet portion 4 is pressed against a rib 53 projecting from the inner wall of the main body case 31 by this force. In this portion, the first chamber 34 and the second chamber 35 of the pressure adjustment chamber 36 are partitioned.

In addition, between the upper part of the valve stem 32 and the main body case 31,
An O-ring 49 is inserted to hermetically seal the first chamber 34. Also, the vicinity of the lower end of the valve stem 32 and the body case 31
Similarly, O-rings 51A and 51B for maintaining airtightness are respectively inserted into the bottom of the.

The automatic pressure regulator of the present invention having the above configuration operates as follows.

First, when the roof not shown rises from the reference position,
Following the movement, the cantilever 42 swings upward to separate the exhaust valve 47 from the orifice 46. As a result, the air spring connection hole 38 and the exhaust hole are removed from the air chamber 8 of the air spring device.
Through 45, air is exhausted in a flow path indicated by a dashed line 55. When the air is discharged in this way, the internal pressure of the air chamber 8 decreases, and the force for supporting the roof decreases. In this way, the roof descends to the reference position.

On the other hand, when the roof falls from the reference position, the cantilever 42 swings and opposes the force of the spring 52 to lower the valve stem 32. At this time, the poppet unit 41
Compressed air flows into the second chamber 35 and the first chamber 34 from the compressor 7 through the compressed air suction hole 37 along the path indicated by a chain line 56 apart from the rib 53 projecting from the main body case 31.

When the internal pressure of the first chamber 34 increases due to the inflow of the compressed air, the internal pressure of the air chamber 8 communicating therewith increases, and the air spring device pushes up the roof. Thereby, the roof is returned to the reference position.

As described above, the apparatus according to the present invention includes one valve stem 32.
Rises and descends following the rise and fall of the roof, whereby the internal pressure of the air chamber 8 is adjusted.

 Further, the device of the present invention has the following features.

FIG. 2 and FIG. 3 show the state of inflow of compressed air when the amount of descent of the roof is large and small, respectively.
As shown in the figure, in the device of the present invention, the valve stem 32 has a small diameter portion 32a and a large diameter portion 32b.

Thus, as can be seen by comparing FIG. 2 and FIG. 3, when the descending amount of the roof is different, the second room is moved from the first room 34 to the second room.
The cross-sectional area of the air flow path leading to the room 35 is changed.

That is, FIG. 2 shows a case where the amount of descending of the roof is large. In this case, the compressed air passes between the main body case 31 and the small diameter portion 32a of the valve stem 32 as indicated by an arrow 56. ,
It flows from the second room 35 toward the first room 34. The cross-sectional area of this air passage is relatively large, and a large amount of compressed air flows in at one time, and as a result, the roof rises rapidly.

On the other hand, FIG. 3 shows a case where the amount of descent of the roof is small, and in this case, it passes through a relatively small air flow path formed between the large diameter portion 32b and the main body case 31, Compressed air flows as indicated by arrow 56. Since the flow rate of air in this case is smaller than that in the case of FIG. 2, the roof rises slowly.

FIG. 4 is a graph showing such a relationship between the flow rate and the displacement of the valve stem. In the figure, the range indicated by A corresponds to the operating state shown in FIG. 3, and the range indicated by B corresponds to the range shown in FIG. , Corresponds to the operation state shown in FIG.

If the flow rate characteristic is changed in a stepwise manner, a so-called hunting phenomenon that the roof moves past the reference position and returns again when the roof approaches the reference position is less likely to occur.

In addition, the sensitivity of the device can be further increased by unifying the valve stem 1 and reducing the hunting of the roof to enable stable levitation. That is, if the sensitivity is high, hunting is likely to occur, but if this hunting can be reduced by the means described above, a more sensitive pressure adjustment can be performed.

As a result, for example, the thickness of the elastic body such as rubber, which is the packing of the poppet portion 41, can be further reduced. As a result, the above-described hysteresis phenomenon and the like can be minimized. Therefore, an automatic pressure regulator with good resilience to the reference position can be provided.

In order to demonstrate the effect of the apparatus of the present invention, the state in which the load returns on the roof and a plurality of air spring devices supporting the same are applied with uneven force so that the roof returns to the original reference position. Observed over time. For such observation, a conventionally known three-dimensional measuring instrument is used, and the results are shown in FIG.

In the figure, the horizontal axis represents time, and the vertical axis represents the displacement of the air spring device that has risen too much from the exhaust side, that is, the reference position, and the displacement of the air spring device that has fallen too much from the supply side, that is, the reference position. .

As shown in the figure, when the bridge of the three-dimensional measuring device moves and stops, the air spring device on the exhaust side returns while displacing as shown in FIG. 5 (a), and the compressed air is supplied from the compressor. The air spring device returned to the reference position while being displaced as shown in FIG.

In the drawing, the portion indicated by the broken line is a dead zone, and the automatic pressure regulator does not operate for a level change of the roof below this dead zone. In the case of the device of the present invention, it is possible to set this dead zone sufficiently narrow.

 The device of the present invention is not limited to the above embodiment.

The orifice 46 at the upper end of the valve stem 32 is provided for adjusting the amount of air discharged, and can be replaced with an orifice having a different orifice diameter as needed so as to obtain predetermined characteristics.

Further, the shape of the valve stem 32 is not limited to the above embodiment. It may be a prismatic shape instead of a columnar shape. In the above embodiment, the air flow path can be adjusted in two stages.
The outer diameter of the valve stem may be tapered so that the flow path of the air gradually increases or decreases without interruption. In addition, the configuration of the poppet may be freely changed as long as the above function can be achieved.

(Effects of the Invention) The automatic pressure regulator of the present invention described above has a single valve stem and is capable of moving the second pressure from the first chamber.
By adjusting the air flow path leading to the room, the occurrence of hunting is sufficiently and effectively prevented. or,
By preventing the occurrence of hunting, the dead zone can be made as small as possible, and the sensitivity can be increased.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the automatic pressure regulator of the present invention, FIGS. 2 and 3 are longitudinal sectional views of a main part during operation, and FIG. FIG. 5 is a graph showing a relationship with displacement, FIG. 5 is a graph showing displacement of a roof of an air spring device using the device of the present invention, FIG. 6 is a longitudinal sectional view showing an embodiment of a conventional automatic pressure regulator, FIG. 7 is a graph showing the relationship between the flow rate and the displacement of the valve stem. 7 Compressor 8 Air chamber 31 Main body case 32 Valve stem 32a Small diameter part 32b Large diameter part 34 First chamber 35 Second Room, 36… Pressure adjustment chamber, 37… Compressed air intake hole, 38 …… Air spring connection hole, 40 …… Flange, 41 …… Poppet part, 42 …… Cantilever, 43 …… Pin, 44,52… ... Spring, 45 ... Exhaust hole, 46 ... Orifice, 47 ... Exhaust valve, 48 ... Shaft, 50,51 ... O-ring, 53 ... Rib.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Tanaka 2-1-1 Oda Sakae, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Inside Showa Electric Wire & Cable Co., Ltd. (58) Fields investigated (Int. Cl. ⁶ , DB name) F16F 9/00-9/32 F16K 17/196

Claims (1)

(57) [Claims] An air chamber of an air spring device for supporting a roof has a pressure adjusting chamber for adjusting the pressure of the air chamber, and the pressure adjusting chamber is connected to the air chamber. An air spring connection hole, a compressed air suction hole connected to a compressor that supplies compressed air, a valve stem that penetrates an outer wall of the pressure adjustment chamber and has one end extending outside the pressure adjustment chamber, An exhaust hole formed in the shaft portion of the valve stem, one end of which is opened inside the pressure adjustment chamber and the other end is opened outside of the pressure adjustment chamber, and a cantilever for detecting the elevation of the roof. An exhaust valve for opening and closing the other end of the exhaust hole by raising and lowering the cantilever, wherein the pressure adjustment chamber includes a first chamber in which one end of the air spring connection hole and the exhaust hole is opened, The second air opening is open The valve stem has a detachable orifice covered on the other end of the exhaust hole, and only when the roof is lowered, with the movement of the valve stem following the valve stem. And a poppet portion for opening a boundary between the first room and the second room is provided, and a cross-sectional area of a flow path of air from the first room to the second room is determined by the poppet portion. In the open state, the automatic pressure regulator is selected to be narrow when the descending amount of the roof is small and wide when the descending amount is large.