JP7632918B2 - Silencers and vacuum pumps - Google Patents

Description

The present invention relates to a silencer used to reduce vibrations and noise caused by exhaust gas discharged from a vacuum exhaust device incorporating a vacuum pump. More specifically, the present invention relates to a silencer in which one or more stages of expansion chambers for silencing are formed in the exhaust flow path, and to a vacuum exhaust device equipped with the silencer.

A mechanical device, for example, a vacuum pump, is a noise source that generates vibrations and noise due to exhaust. In order to suppress noise due to exhaust, a silencer is attached to the exhaust side of the mechanical device that is the noise source. There are two types of silencers: a built-in type that is built into the mechanical device that is the noise source and exhaust passes through the silencer before being discharged to the outside, and an external type that is attached to the exhaust port of the mechanical device. In addition, a mechanism for silencing is known in which one or more expansion chambers for silencing are arranged along the exhaust passage. Patent documents 1 and 2 propose a vacuum pump equipped with an external type silencer. The silencer described in Patent document 1 introduces outside air from the exhaust port of the vacuum pump through a check valve and discharges exhaust to the outside through an expansion chamber (expansion chamber) for silencing. In the silencer described in Patent document 2, the exhaust of the vacuum pump discharged through the check valve is introduced into the silencer through a throttle valve mechanism, and the silencer characteristics can be adjusted by the throttle valve mechanism.

International Publication No. 2018/220943 JP 2001-289167 A

Built-in type mufflers do not require space to be secured around the periphery of the machinery for mounting the muffler. External type mufflers require space to be secured around the periphery of the machinery, and securing the space to mount the muffler may be difficult depending on the installation location. In either type of muffler, the muffler characteristics, such as the exhaust flow passage diameter and the volume of the expansion chamber, are set in advance according to the frequency of the noise generated by the machinery to be mounted, which is the noise source, so that a specified muffler effect can be obtained. In order to change the muffler's muffler characteristics and performance without replacing it, it is necessary to attach a throttle valve mechanism, as described in Patent Document 2.

In view of these points, the object of the present invention is to provide a silencer having a compact configuration whose silencing characteristics and performance can be easily changed and which requires a relatively small installation space.

In order to solve the above problems, the present invention provides a silencer for reducing noise caused by exhaust gas discharged from a mechanical device such as a vacuum pump, comprising:
an exhaust flow path through which the exhaust gas flows;
a silencer case having the exhaust passage formed therein;
It has
the exhaust flow path includes an upstream flow path portion, a downstream flow path portion, and a sound-deadening extension chamber formed between the upstream flow path portion and the downstream flow path portion,
the silencer case includes an apparatus-side case that is integrally formed with or fixed to a component of the mechanical device, and an external case that is detachably connected to the apparatus-side case,
the upstream flow path portion is formed inside the device case,
The downstream flow path portion is formed inside the external case,
The expansion chamber is characterized in that it is formed inside the device side case, inside the external side case, or inside a case connecting portion between the device side case and the external side case.

In the silencer of the present invention, a downstream flow passage portion of the exhaust flow passage is formed inside the external case. In addition, for example, a part or all of an expansion chamber is formed inside the external case. A high silencing effect can be obtained by using an external case with a downstream flow passage portion of a predetermined flow passage diameter and flow passage length, or an external case capable of forming an expansion chamber of a predetermined volume, depending on the noise frequency, etc., of the mechanical device to which the silencer is attached. The silencing characteristics of the silencer can be easily changed by replacing the external case as necessary.

In addition, because the device-side case of the silencer case is integrally formed or fixed to the components of the mechanical device that is the noise source, it is effective in reducing the cost of the silencer. All that is required is to secure the installation space required for attaching the external case that constitutes the remaining part of the silencer on the outside of the mechanical device to which it is to be attached.

In the silencer of the present invention, the case connection portion between the device-side case and the external-side case is configured, for example, as follows: the device-side case has a first cylindrical end portion with an open end face, the external-side case has a second cylindrical end portion with an open end face, one of the first cylindrical end portion and the second cylindrical end portion has a male thread formed on its outer circumferential surface, and the other has a female thread formed on its inner circumferential surface into which the male thread can be screwed, and the second cylindrical end portion is screwed and fixed to the first cylindrical end portion.
In this case, the external case can be attached to the device case without the need for additional fasteners such as bolts or screws, and replacement work is also easy.

The silencer of the present invention is provided with a communication passage forming part in which a communication passage is formed that connects the upstream flow path portion and the expansion chamber, and the communication passage forming part may be removably attached inside the device side case or the external side case.
In this case, a high noise reduction effect can be obtained by installing a communication passage forming part that has a communication passage with a flow passage diameter and flow passage length suitable for reducing noise from the mechanical device. The noise reduction characteristics and performance of the silencer can be changed by replacing the installed communication passage forming part with a communication passage with a different flow passage diameter and flow passage length.

The silencer of the present invention is provided with a check valve capable of blocking a communication passage connecting the upstream flow path portion and the expansion chamber from the side of the expansion chamber, and the check valve may have a spherical valve body arranged inside the expansion chamber.
For example, in the case where the mechanical device is a vacuum exhaust device used in a semiconductor manufacturing system, the vacuum inside the mechanical device can be maintained without installing a separate check valve.

1 is an explanatory diagram showing a dry vacuum pump equipped with a silencer according to an embodiment of the present invention; FIG. 2 is a schematic vertical cross-sectional view showing the muffler of FIG. 1 . FIG. 2 is a half-sectional perspective view showing a main portion of the silencer of FIG. 1 . FIG. 2 is an exploded view showing the main components of the silencer of FIG. 1 .

Below, an embodiment of a silencer to which the present invention is applied will be described with reference to the drawings. Note that the embodiment described below shows one example of the present invention, and is not intended to limit the present invention to the embodiment.

Figure 1 is an explanatory diagram showing a vacuum exhaust device equipped with a silencer according to an embodiment. The vacuum exhaust device 1 is equipped with two dry vacuum pumps connected in series inside a rectangular parallelepiped device housing 2. For example, the vacuum exhaust device 1 is equipped with a mechanical booster pump 3 in the front stage and a dry vacuum pump 4 in the rear stage. Of course, various types of dry vacuum pumps can be used, such as a screw type vacuum pump, a roots type, a claw type, or a scroll type.

The intake port 5 and exhaust port 6 of the vacuum exhaust device 1 are arranged, for example, on the housing top surface 2a of the device housing 2. An intake pipe 8 is connected to the intake port 5 via an intake port joint (not shown). A silencer 10 according to the embodiment is attached to the exhaust port 6. The exhaust from the exhaust port 6 passes through the silencer 10 and is then discharged via an exhaust pipe 9 connected to the silencer 10.

Figure 2 is a schematic vertical cross-sectional view showing the silencer 10, Figure 3 is a half-sectional perspective view showing the main parts of the silencer 10, and Figure 4 is an exploded view showing the main components of the silencer 10. The silencer 10 has a silencer case 10A in which an exhaust flow path 11 is formed, through which the exhaust gas discharged from the exhaust port 6 flows. The silencer case 10A is composed of a cylindrical device-side case 20 and a cylindrical external case 30 that is coaxially connected to the device-side case 20 in a removable form.

In the exhaust flow path 11, an inlet 12, an inlet passage 13, an upstream expansion chamber 14, a communication passage 15, a downstream expansion chamber 16, an outlet passage 17, and an outlet 18 are formed along the exhaust flow direction. An upstream flow path portion (inlet 12, inlet passage 13, upstream expansion chamber 14, and communication passage 15) is formed inside the device side case 20. In this example, the communication passage 15 is defined by a through hole formed in the communication passage forming plate 40 (communication passage forming part) attached inside the device side case 20. Meanwhile, a downstream expansion chamber 16 and a downstream flow path portion (outlet passage 17 and outlet 18) are formed inside the external case 30.

In addition, the silencer 10 in this example is a silencer device with a check valve, and is equipped with an upstream check valve 50 that can seal the space between the inlet passage 13 and the upstream expansion chamber 14 from the upstream expansion chamber 14 side, and a downstream check valve 60 that can seal the space between the connecting passage 15 and the expansion chamber 16 from the downstream expansion chamber 16 side.

When the external case 30 is attached to the device-side case 20, an expansion chamber 16 sealed from the outside is formed, and when the external case 30 is removed from the device-side case 20, the downstream expansion chamber 16 opens to the outside. A case connection portion between the device-side case 20 and the external case 30 is configured so that. Also, when the external case 30 is removed from the device-side case 20, the communication passage forming plate 40 can be removed from the device-side case 20.

The exhaust gas from the vacuum exhaust device 1 flows from the exhaust port 6 through the inlet 12 in the exhaust flow path 11 of the silencer 10 into the inlet 13, and flows into the upstream expansion chamber 14 through the upstream check valve 50. The upstream expansion chamber 14 has a predetermined volume with a larger flow path area than the inlet 13. The exhaust gas flows from the upstream expansion chamber 14 through the connecting passage 15 with a narrowed flow path area and the downstream check valve 60 into the downstream expansion chamber 16 with a wide flow path area and a predetermined volume. The exhaust gas that flows into the downstream expansion chamber 16 is discharged from the outlet 18 through the outlet path 17 with a narrowed flow path area. The exhaust gas that flows out from the outlet 18 is discharged into the exhaust pipe 9 connected to the outlet 18. By discharging the exhaust gas from the vacuum exhaust device 1 into the exhaust pipe 9 through the silencer 10 with a two-stage silencing expansion chamber structure, the vibration and noise caused by the exhaust gas are suppressed. Furthermore, the upstream check valve 50 and the downstream check valve 60 can prevent backflow of exhaust gas, making it possible to maintain a vacuum on the upstream side even when the vacuum exhaust device 1 is not in operation.

2 to 4, the device side case 20, the external side case 30, and the communication passage forming plate 40 will be described. First, the device side case 20 is a part integrally formed with device components 19, such as the housing components that define the housing top surface 2a of the device housing 2 of the vacuum exhaust device 1, and the pump housing components of the downstream dry vacuum pump 4 that are arranged inside the housing, or a part fixed to the device components 19. This device side case 20 comprises, from the upstream side to the downstream side in the exhaust flow direction, an upstream side tubular section 21, an intermediate tubular section 22, and a downstream side tubular section 23.

An inlet port 12 opens at the upstream end face of the upstream cylindrical portion 21, and an inlet passage 13 is formed inside the upstream cylindrical portion 21. An upstream expansion chamber 14 is formed inside the intermediate cylindrical portion 22 and has a rectangular parallelepiped shape with a predetermined volume and a larger flow passage area than the inlet passage 13. In the upstream cylindrical portion 21, a tapered seating surface 51 is formed on the inner circumferential surface between the inlet passage 13 and the upstream expansion chamber 14, with the inner diameter gradually increasing from the inlet passage 13 toward the upstream expansion chamber 14. The seating surface 51 and a spherical valve body 52 inserted in a freely movable state into the upstream expansion chamber 14 constitute an upstream check valve 50.

The downstream cylinder 23 of the device case 20 has a screw hole 23b of a predetermined depth formed on the downstream side thereof, which opens to the end face 23a. That is, a female screw 26 is formed on the circular inner peripheral surface of the downstream cylinder 23 over a predetermined range from the end face 23a side. In addition, a receiving portion 27 for the communication passage forming plate 40 is formed at the bottom of the screw hole 23b by protruding the inner peripheral surface of the screw hole inward by a certain width.

The communication passage forming plate 40 has a through hole penetrating in the thickness direction in the center of the disk, which is large enough to be inserted into the screw hole 23b, and this through hole defines the communication passage 15. The communication passage forming plate 40 is inserted into the screw hole 23b opening in the end face 23a of the downstream side cylindrical portion 23 of the device side case 20, and is positioned by abutting against the receiving portion 27 formed at the bottom. The communication passage forming plate 40 has a tapered seating surface 61 formed on its downstream end face 43, which widens toward the downstream side in a state surrounding the communication passage 15. The downstream check valve 60 is composed of the seating surface 61 and a spherical valve body 62 that is movably inserted into the downstream expansion chamber 16.

Next, the external case 30 comprises an upstream tubular portion 31 that can form the downstream expansion chamber 16 by attaching it to the device case 20, and a downstream tubular portion 32 in which the outflow passage 17 is formed and the outflow port 18 opens to the downstream end face. A circular mounting flange 33 is formed on the outer periphery of the downstream end of the downstream tubular portion 32, to which the exhaust pipe 9 can be connected.

A connecting cylindrical portion 34 protrudes coaxially from the end face 31a of the upstream side tube portion 31 of the external case 30. The connecting cylindrical portion 34 (second cylindrical end portion) has an opening at its end face 34a, and a male screw 35 is formed on its circular outer circumferential surface. The male screw 35 can be coaxially screwed into the screw hole 23b of the downstream side tube portion 23 (first cylindrical end portion) of the device side case 20 and fixed. In this example, the length of the upstream side tube portion 31 of the external case 30 is shorter than the depth of the screw hole 23b of the downstream side tube portion 23 of the device side case 20. The connecting passage forming plate 40 is sandwiched between the end face 34a of the connecting cylindrical portion 34 screwed into the screw hole 23b and the annular receiving portion 27 formed at the bottom of the screw hole 23b of the device side case 20, so that the connecting passage forming plate 40 is attached inside the device side case 20.

When attaching the external case 30, the spherical valve body 52 is inserted into the upstream expansion chamber 14 of the device-side case 20. The communication passage forming plate 40 is inserted into the screw hole 23b of the downstream cylindrical portion 23 of the device-side case 20 and placed on the annular receiving portion 27, and the spherical valve body 62 is inserted and placed on the seating surface 61 of the communication passage forming plate 40. Next, the communication passage forming plate 40 is sandwiched, and the connecting cylindrical portion 34 (second cylindrical end) of the external case 30 is screwed coaxially into the screw hole 23b of the downstream cylindrical portion 23 (second cylindrical end) of the device-side case 20 and fixed. As a result, the internal space of the upstream cylindrical portion 31 of the external case 30 is sealed from the outside, and the downstream expansion chamber 16 is formed between the inner peripheral surface of the upstream cylindrical portion 31 and the downstream end surface 43 of the communication passage forming plate 40 attached to the device-side case 20. Furthermore, a downstream check valve 60 equipped with a spherical valve body 62 is incorporated inside the downstream expansion chamber 16 .

O-ring mounting grooves 44, 28 are formed on the outer peripheral edge of the upstream end face 42 of the communication passage forming plate 40 and on the end face 23a of the downstream cylindrical portion 23 of the device side case 20, respectively. With O-rings 71, 72 mounted in the O-ring mounting grooves 44, 28, respectively, the external case 30 is screwed and fixed to the device side case 20. This seals the screw fastening surface of the case connection part between the device side case 20 and the external case 30, ensuring airtightness of the exhaust flow path 11.

As described above, the silencer case 10A of the silencer 10 of this example is composed of the device-side case 20 formed or fixed on the side of the components of the vacuum exhaust device 1, and the external case 30 removably connected to the device-side case 20. When the external case 30 is removed from the device-side case 20, the exhaust flow path 11 is separated at the downstream expansion chamber 16, and the downstream expansion chamber 16 is open to the outside. That is, the opening of the downstream end face 23a of the device-side case 20 and the opening of the upstream end face 34a of the external case 30 are exposed to the outside. Through the opening of the end face 23a of the device-side case 20, the spherical valve body 52 of the upstream check valve 50 can be inserted and removed, and the communication passage forming plate 40 can be inserted and removed. Through the opening of the end face 34a on the external case 30 side, the spherical valve body 62 of the downstream check valve 60 can be inserted and removed.

By sandwiching the communication passage forming plate 40 and attaching the external case 30 to the device side case 20, an exhaust flow path 11 for silencing is obtained in which the downstream expansion chamber 16 is connected to the upstream expansion chamber 14 via the communication passage 15. The external case 30 and the communication passage forming plate 40 that provide appropriate sound silencing characteristics can be attached to the device side case 20 according to the noise frequency of the vacuum exhaust device 1, which is the noise source. In addition, if necessary, the downstream expansion chamber 16 can be changed to an expansion chamber of a different volume by replacing the external case 30. The communication passage 15 can be changed to a different flow path diameter or flow path length by replacing the communication passage forming plate 40.

For example, multiple types of replacement external cases 30 are prepared, each of which has a common male thread 35 formed on the outer circumferential surface of the connecting cylindrical portion 34, but has different inner diameters and lengths of the portion forming the downstream expansion chamber 16, and different inner diameters and lengths of the outflow passage 17. In this case, the replacement part that is most effective in reducing the noise of the mechanical device to be silenced can be selected from these replacement parts and attached to the device case 20.

In addition, in the silencer 10 of this example, screw fastening is used as a mechanism for detachably fastening the external case 30 to the device case 20. Compared to a fastening mechanism that uses fastening metal fittings such as bolts and nuts, the number of parts required is smaller, and increases in the dimensions and costs of the silencer 10 can be suppressed. In addition, airtightness can be ensured by applying sealing tape to the threaded portion and coating it with a sealant.

Furthermore, in this example, the communication passage forming plate 40, which defines the communication passage 15 that connects the upstream expansion chamber 14 and the downstream expansion chamber 16, is sandwiched between the external case 30 and the device side case 20. This simplifies the structure for fixing the communication passage forming plate 40 to the device side case 20, reducing the cost of the silencer 10 and suppressing an increase in size. In addition, since the communication passage forming plate 40 is a disc-shaped part with a predetermined thickness, it is effective in suppressing an increase in size of the silencer 10.

On the other hand, the silencer 10 of this example is attached to the exhaust port 6 of the vacuum exhaust device 1 for use. In order to prevent exhaust gas from flowing back into the vacuum exhaust device 1, spherical valve bodies 52, 62 for forming the upstream check valve 50 and downstream check valve 60 are inserted into the upstream expansion chamber 14 and downstream expansion chamber 16 of the silencer 10, respectively. The spherical valve bodies 52, 62 are seated on the tapered seating surfaces 51, 61 from the downstream side, thereby preventing or suppressing the backflow of exhaust gas. The internal space of the upstream expansion chamber 14 and downstream expansion chamber 16 is used as the installation space for the spherical valve bodies 52, 62, and these seating surfaces 51, 61 are formed on the inner peripheral surface at the upstream end of the upstream expansion chamber 14 and the downstream end surface of the communication passage forming plate 40. Therefore, since there is no need to install a separate check valve between the exhaust port 6 and the silencer 10, a small and compact check valve mechanism can be realized that can maintain a vacuum even when the vacuum exhaust device 1 is not in operation.

Other Embodiments
(1) The above-mentioned silencer 10 functions as a check valve by inserting the spherical valve bodies 52, 62 into the upstream expansion chamber 14 and the downstream expansion chamber 16 formed therein. When used in fluid machinery other than a vacuum exhaust device, the check valve can be omitted.
(2) In the silencer 10, the communication passage forming plate 40 is a replaceable part, but the communication passage 15 may be formed integrally with the device-side case 20.
(3) The silencer 10 has a two-stage expansion chamber structure, but the present invention is similarly applicable to a silencer having a single stage of expansion chamber, or a silencer having three or more stages of expansion chambers.
(4) In the silencer 10, the exhaust flow path 11 can be divided into two parts, the upstream side and the downstream side, in the exhaust flow direction at the downstream expansion chamber 16. In addition, the external case 30 can also be a case with a divided structure.

Claims (5)

A silencer for reducing noise caused by exhaust from a mechanical device, comprising:
an exhaust flow path through which the exhaust gas flows;
a silencer case having the exhaust passage formed therein;
It has
the exhaust flow path includes an upstream flow path portion, a downstream flow path portion, and a sound-deadening extension chamber formed between the upstream flow path portion and the downstream flow path portion,
the silencer case includes an apparatus-side case that is integrally formed with or fixed to a component of the mechanical device, and an external case that is detachably connected to the apparatus-side case,
Furthermore,
a communication passage forming component in which a communication passage that communicates between the upstream flow path portion and the expansion chamber is formed, and a check valve capable of closing the communication passage from the expansion chamber side, the check valve having a spherical valve body disposed inside the expansion chamber,
The expansion chamber is formed inside a case connection portion between the device case and the external case,
the communication passage forming component is removably attached to the inside of the device-side case,
The device side case has a first cylindrical end face with an opening on the downstream side, and the external attachment side case has a second cylindrical end face with an opening on the upstream side, and a male thread is formed on the outer peripheral surface of one of the first cylindrical end and the second cylindrical end, and a female thread that can be screwed into the male thread is formed on the inner peripheral surface of the other , and the case connection part is formed by screwing and fixing the second cylindrical end into the first cylindrical end. 2. The silencer according to claim 1,
The external case includes a plurality of replacement external cases capable of forming the expansion chambers having different volumes,
A silencer capable of selectively attaching one of the replacement external cases to the device case. The silencer according to claim 1, further comprising:
A silencer comprising an upstream expansion chamber for silencing noise formed midway through the upstream flow passage portion. 2. The silencer according to claim 1,
The communication passage forming parts include a plurality of replacement communication passage forming parts each having the communication passage with a different flow path diameter,
A silencer in which one of the replacement communication passage forming parts can be selectively attached to the apparatus side case. 5. A vacuum exhaust system comprising the silencer according to claim 1 attached to an exhaust port.

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