JPH09268989A - Muffler for liquid sealed vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a muffler for reducing noise (liquid discharge nose, impeller blade passing noise in particular) given from a liquid sealed vacuum pump, in a simple structure and at a low cost. SOLUTION: A muffler which is mounted on an outlet pipe 5 for a liquid sealed vacuum pump in use has the first chamber 11 connected to the outlet pipe 5, the second chamber 12 connected to the first chamber 11 via a communication passage 13 and a liquid discharge pipe 15 and an air exhaust pipe 16 connected to the second chamber 12. The cross section of the first chamber 11 is set larger than that of the outlet pipe 5 and the cross section of the communication passage 13 is set smaller than those of the first and second chambers 11, 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a muffler attached to a discharge pipe of a liquid ring vacuum pump for use.

[0002]

2. Description of the Related Art As is well known, in a liquid ring vacuum pump, a liquid (for example, water) in a casing forms an annular flow along an inner wall of the casing as the impeller rotates, and the liquid is impeller. The gas (for example, air) is sucked and discharged as the gas moves in the radial direction, and the gas is pumped or removed. In this type of liquid ring vacuum pump, since the liquid (sealing liquid) in the casing is discharged together with the exhaust gas, it is necessary to replenish it sequentially. Further, in this liquid ring vacuum pump, since the pumping action is performed by using the liquid, it is also used for sucking the gas containing the liquid droplets.

By the way, in such a liquid ring vacuum pump, since a small amount of the sealing liquid is discharged together with the discharge of the gas, the flow in the drain pipe is a gas-liquid two-phase flow. Moreover, this flow pattern changes variously depending on the intake air amount. For example, when the intake air amount is large, the liquid flow in the drain pipe becomes an annular flow along the inner wall surface of the drain pipe, and the sound inside the pump (for example, the sound of the impeller blades passing through) passes through the air layer. And leaks out. Further, at this time, the noise of the drainage flowing through the drain pipe is loud, and the problem of noise occurs. In addition, the pressure loss of the two-phase flow increases the back pressure of the liquid ring vacuum pump. In such a liquid ring vacuum pump, if the back pressure increases,
Since the amount of work applied to the vacuum pump increases, the driving force increases, and in this vacuum pump, the ultimate vacuum pressure becomes high because the compression ratio is substantially constant.

Generally, a liquid-sealed vacuum pump tends to have larger noise and back pressure as it has a larger capacity. Therefore, a silencer may be attached to the discharge pipe of the liquid-sealed vacuum pump. As this silencer, a centrifugal separator is generally widely used as a standard. This centrifugal separation type muffler-type separator has a discharge pipe of a vacuum pump connected to an inlet pipe provided in a tangential direction substantially at the center of a side wall portion of the separation cylinder, and the gas-liquid two-phase is introduced into the separation cylinder through the introduction pipe. Liquid and gas are separated by introducing a flow and swirling inside the separation cylinder,
The liquid is discharged through a drain pipe connected to the lower end of the separation cylinder, and the gas is discharged through an exhaust pipe connected to the upper end of the separation cylinder. However, such a centrifugal separation type sound deadening separator requires a large space and is expensive because the separation cylinder tends to have a large diameter.

[0005]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to reduce the noise of a liquid ring type vacuum pump (especially drainage noise,
(EN) It is an object to provide a muffling device that reduces (passing sound of a wing) with a simple configuration and provide it at a low cost.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a sound deadening device mounted on a discharge pipe of a liquid ring vacuum pump for use.
A first chamber connected to the discharge pipe, a second chamber connected to the first chamber via a communication passage, and a drain pipe and an exhaust pipe connected to the second chamber. The above problem is solved by a configuration in which the cross-sectional area of one chamber is set to be larger than that of the discharge pipe and the cross-sectional area of the exhaust pipe is set to be smaller than that of the second chamber. Further, in the present invention, the first chamber and the second chamber are constituted by T-shaped pipe members having branch portions on the side surfaces, and the branch portions of the T-shaped pipe members are internally provided with communication passages. The T-shaped piping member constituting the first chamber is connected to the discharge pipe of the liquid-sealed vacuum pump, and the other opening of the T-shaped pipe member constituting the first chamber is closed. And the second
The above problem is solved by a configuration in which a drainage pipe is connected to one of two opposing opening portions of a T-shaped pipe member forming a chamber and an exhaust pipe is connected to the other opening portion.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiment of the present invention, a muffler attached to a discharge pipe of a liquid ring vacuum pump for use is connected to a first chamber connected to the discharge pipe and to the first chamber. The second chamber is connected via a passage, and the drain pipe and the exhaust pipe are connected to the second chamber. The cross-sectional area of the first chamber is set larger than that of the discharge pipe. It is realized by setting the cross-sectional area of (1) smaller than the cross-sectional area of the first and second chambers. That is, the present invention introduces the gas-liquid two-phase flow from the discharge pipe of the liquid ring vacuum pump into the first chamber, which is a large space having a larger cross-sectional area than the discharge pipe,
Separate into gas and liquid. The separated gas and liquid flow into the second chamber through the communication passage, and the liquid is discharged from the drain pipe and the gas is discharged from the exhaust pipe. On this occasion,
Since the gas discharged from the second chamber is discharged from the second chamber to the atmosphere through the exhaust pipe having a small cross-sectional area, noise accompanying the discharge of the gas is reduced. In other words, the structure is such that the cross-sectional area is reduced using the principle of the expansion silencer before exhausting. Here, the cross-sectional area refers to the cross-sectional area of the flow path, and is a cross-section for the gas-liquid two-phase flow from the liquid ring vacuum pump and the flow directions of gas and liquid contained in the gas-liquid two-phase flow. It particularly refers to the area.

Further, the present invention can be easily realized by combining the silencer with existing piping parts. That is, the first chamber and the second chamber are configured by a T-shaped pipe member (generally called cheese) having a branched portion on a side surface, and the branched portions of each T-shaped pipe member are internally formed. The first chamber and the second chamber are connected by connecting with a communication pipe having a communication passage formed therein. Further, one of the two facing openings of the T-shaped piping member forming the first chamber is connected to the discharge pipe of the liquid ring vacuum pump, and the other opening is closed, and the first opening is closed. The drain pipe is connected to one of the two opposing opening portions of the T-shaped pipe member forming the two chambers, and the exhaust pipe is connected to the other opening portion. As described above, the silencer for the liquid ring vacuum pump according to the present invention can be easily configured by the existing piping parts.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of a silencer for a liquid ring vacuum pump according to the present invention will be described in detail below with reference to FIGS. 1 is a drawing for explaining a side surface shape of an embodiment of a silencer for a liquid ring vacuum pump according to the present invention, and FIG. 2 is a plan view of FIG.

In the embodiment shown in the drawings, a liquid-sealed vacuum pump 1 has a structure in which a drive unit 3 is connected to a pump body 2, and a suction pipe of the liquid-sealed vacuum pump 1 and a supply port for the sealed water. Etc. are omitted. The silencer 10 according to the present invention is connected to the discharge pipe 5 of the liquid ring vacuum pump 1. The silencer 10 in this specific example shows an example constituted by existing piping parts.

The silencer 10 includes a first chamber 11 connected to the discharge pipe 5 of the liquid ring vacuum pump 1, and a second chamber 12 connected to the first chamber 11 via a communication passage 13. Equipped with. Further, a drain pipe 15 and an exhaust pipe 16 are connected to the second chamber 12. Here, the cross-sectional area of the first chamber 11 is set larger than that of the discharge pipe 5 of the liquid ring vacuum pump 1, and the cross-sectional area of the exhaust pipe 16 is set smaller than that of the second chamber 12. There is.

The first chamber 11 is constituted by a T-shaped pipe member 20 having a branch portion 20a on its side surface, and the lower opening of the two opposed opening portions of the T-shaped pipe member 20. The discharge pipe 5 from the liquid ring vacuum pump 1 is connected to the portion 20b, and the opening 20c on the upper side is provided with the lid member 2
It is closed by providing 2. The second chamber 12 also
Like the first chamber 11, the T having the branch portion 21a on the side surface
The drain pipe 15 is connected to the lower opening 21b of the two opposing openings of the T-shaped piping member 21, and the upper opening 21 is formed.
An exhaust pipe 16 is connected to c. A communication pipe 23 is connected between the branch portions 20a, 21a of the T-shaped pipe members 20, 21, and the first chamber 11 and the second chamber 12 communicate with each other by a communication passage 13 inside the communication pipe 23. To do.

In the above construction, the discharge pipe 5 and the communication passage 13 are in a direction intersecting with each other (in this embodiment, they are substantially orthogonal to each other), and the communication passage 13, the drain pipe 15 and the exhaust gas are exhausted. The pipe 16 and the communication passage 13 are in a direction intersecting with each other (in this embodiment, a substantially orthogonal state). Therefore, the discharge pipe 5, the drainage pipe 15, and the exhaust pipe 16 are in a substantially parallel state. In addition, each T-shaped pipe member 20, 2
1, the branch portions 20a and 21a and the openings 20
The inner diameters of b, 20c, 21b and 21c are substantially the same. Further, in the branch portions 20a and 21a, the communication pipe 23
Since they are inserted inside and connected to each other, the flow passage cross-sectional area of the communication passage 13 inside the communication pipe 23 is equal to each of the openings 20b and 20.
It is slightly smaller than the flow passage cross-sectional area at c, 21b, and 21c. Further, in the first chamber 11, the flow passage cross-sectional area is set to be larger than that of the discharge pipe 5 of the liquid ring vacuum pump 1, but in order to obtain a predetermined gas-liquid separation performance,
At least the area ratio is set to about 10 or more. Further, the cross-sectional area of the exhaust pipe 16 is equal to that of the second chamber 12
The muffling performance is improved as the cross-sectional area is set to be smaller than the cross-sectional area. However, for example, the muffling performance is obtained when the exhaust noise is reduced to the same level as the noise of the pump itself (there is usually a difference of about 10 db). In order to achieve this, at least the area ratio is set to about 0.1 or more.

In the above structure, the liquid ring vacuum pump 1
When the operation is started, a small amount of the sealing liquid is discharged from the discharge pipe 5 together with the gas sucked and discharged by the liquid ring vacuum pump 1, so that the flow in the discharge pipe 5 becomes a gas-liquid two-phase flow. Become. This gas-liquid two-phase flow passes from the discharge pipe 5 to the first chamber 1
At the time of flowing into 1, the gas contained in the gas-liquid two-phase flow expands rapidly due to the difference in cross-sectional area, so that the gas and the liquid are separated. Here, even if a gas-liquid two-phase flow is ejected from the discharge pipe 5 and flows into the first chamber 11, the gas-liquid two-phase flow is separated into a gas and a liquid by colliding with the lid member 22. The second chamber 1 is left in the gas-liquid two-phase flow.
It never flows into 2. The gas and the liquid separated in the first chamber 11 in this way pass through the communication passage 13 to the second chamber 1
2, liquid is discharged from the drain pipe 15, and gas is discharged from the exhaust pipe 16, respectively. At this time, the gas flowing into the second chamber 12 has a smaller cross-sectional area than the second chamber 12.
The exhaust gas is exhausted through the space 3 in a wide space during standby, but at this time, since the exhaust pipe 16 is once throttled, noise accompanying exhaust of gas is reduced.

[0015]

As described above, in the silencer for a liquid ring vacuum pump according to the present invention, the gas-liquid two-phase flow from the discharge pipe of the liquid ring vacuum pump has a larger cross-sectional area than this discharge pipe. , And is separated into a gas and a liquid by being introduced into the first chamber, which is a wide space, and the separated gas is further separated into the second chamber.
By exhausting gas from the chamber to the atmosphere through an exhaust pipe with a small cross-sectional area, noise accompanying gas exhaust and noise inside the pump (for example, the sound of impeller blades passing through) leaks out through the air layer. Can be prevented. Further, since it is possible to prevent an increase in back pressure in the liquid ring vacuum pump, it is possible to prevent problems such as an increase in driving force and an increase in vacuum ultimate pressure. Further, the sound deadening device for a liquid ring vacuum pump according to the present invention can be easily configured by a general commercially available piping member, and is therefore inexpensive and space-saving.

[Brief description of drawings]

FIG. 1 is a view for explaining a side surface shape of an embodiment of a silencer for a liquid ring vacuum pump according to the present invention.

FIG. 2 is a plan view of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid-sealed vacuum pump 5 Discharge pipe 10 Silencer 11 First chamber 12 Second chamber 13 Communication passage 15 Discharge pipe 16 Exhaust pipe 20 T-shaped piping member 20a Branch 20b Opening 20c Opening 21 T-shaped piping Member 21a Branch part 21b Opening part 21c Opening part 23 Communication pipe

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshifumi Kuniwa 7 Horie-cho, Matsuyama-shi, Ehime Miura Industry Co., Ltd.

Claims (2)

[Claims] 1. A muffler mounted on a discharge pipe 5 of a liquid ring vacuum pump for use, comprising: a first chamber 11 connected to the discharge pipe 5; and a communication passage 13 connected to the first chamber 11. The second chamber 12 connected to the first chamber 11 and the drain pipe 15 and the exhaust pipe 16 connected to the second chamber 12.
The cross-sectional area of the exhaust pipe 16 is set to be larger than that of the exhaust pipe 5, and the cross-sectional area of the exhaust pipe 16 is set to be smaller than that of the second chamber 12. 2. The first chamber 11 and the second chamber 12,
T-shaped piping member 2 having branch portions 20a and 21a on the side surface
0 and 21, and each T-shaped pipe member 2
0, 21 branching portions 20a, 21a are internally connected to each other through a communication passage 1
One of the two opposing openings 2 of the T-shaped piping member 20 which is connected by the communication pipe 23 forming the third chamber and constitutes the first chamber.
0b is connected to the discharge pipe 5 of the liquid ring vacuum pump 1 and the other opening 20c is closed, and the second chamber 12
2. The drain pipe 15 is connected to one of the two openings 21b of the T-shaped pipe member 21 facing each other, which is opposed to the drain pipe 15, and the exhaust pipe 16 is connected to the other opening 21c. A silencer for the liquid ring vacuum pump described.