Vacuum pump

Abstract

This invention provides a vacuum pump that can improve the function of a silencer. The vacuum pump has a silencer structure with a gas exhaust flow path. The silencer structure has a flat base plate forming the bottom of the exhaust flow path. The exhaust flow path is a planar flow path formed on the base plate.

Description

Technical Field

[0001] This invention relates to a vacuum pump. Background Technology

[0002] Dry vacuum pumps, as an example of vacuum pumps, are used in semiconductor manufacturing equipment to expel gas from a vacuum chamber. A representative example of a dry vacuum pump is a positive displacement vacuum pump, which uses a motor to rotate a pair of pump rotors in opposite directions, moving the gas in the vacuum chamber from the upstream side (i.e., the pump's suction side) to the downstream side (i.e., the pump's exhaust side). In this way, the vacuum pump creates a vacuum in the vacuum chamber.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1: Japanese Patent No. 7350398.

[0006] Patent document 2: Japanese Patent No. 6997719.

[0007] Patent document 3: Japanese Patent No. 6473283.

[0008] The technical problem that the invention aims to solve

[0009] Vacuum pumps sometimes have silencers to reduce the noise generated by the gas they expel (exhaust noise). Even a general silencer can achieve a noise reduction effect, but from the point of view of improving the performance of the vacuum pump, it is important to improve the function of the silencer.

[0010] Depending on the type of gas discharged from the vacuum pump, byproducts may sometimes be generated through chemical reactions, and sometimes the gas may contain moisture. In such cases, as the gas is discharged, byproducts and moisture gradually accumulate in the exhaust path formed in the muffler, potentially causing blockage. To improve the muffler's performance, it is important to prevent muffler malfunctions caused by the discharged gas. Summary of the Invention

[0011] Therefore, the object of the present invention is to provide a vacuum pump that can improve the function of a silencer.

[0012] Technical means for solving technical problems

[0013] In one embodiment, a vacuum pump is provided. The vacuum pump comprises: a pair of pump rotors that compress a gas; a pump housing that houses the pair of pump rotors; and a silencer structure having an exhaust flow path for the gas, the silencer structure having a flat base plate that forms the bottom of the exhaust flow path, the exhaust flow path being a planar flow path formed on the base plate.

[0014] In one embodiment, the muffler structure includes: an expansion chamber forming part of the exhaust flow path; a resonance chamber connected to the expansion chamber; and a thin tube connecting the expansion chamber and the resonance chamber.

[0015] In one embodiment, the capillary portion is formed by a space created on the base plate.

[0016] In one embodiment, the muffler structure includes a water storage section for retaining moisture in the gas, the water storage section being configured adjacent to the capillary section.

[0017] In one embodiment, the muffler structure includes: an inlet flow path for introducing the gas into the exhaust flow path; and an exhaust port for discharging the gas that has passed through the exhaust flow path, the inlet flow path and the exhaust port extending downward in a vertical direction, respectively.

[0018] In one embodiment, the base plate is inclined from the inlet flow path toward the exhaust port.

[0019] In one embodiment, the vacuum pump includes a check valve configured in an inlet path for introducing the gas into the exhaust path. The check valve includes: a ball that opens and closes the inlet path; and a spring that applies force to the ball.

[0020] In one approach, a vacuum pump is provided. The vacuum pump comprises: a pair of pump rotors that compress a gas; a pump housing that houses the pair of pump rotors; and a silencer structure having an exhaust flow path for the gas, the silencer structure comprising: an expansion chamber that forms part of the exhaust flow path; and a resonance chamber connected to the expansion chamber.

[0021] In one embodiment, when the expansion chamber is defined as a first expansion chamber, the muffler structure has a second expansion chamber, and when the muffler structure is viewed from the side, the first expansion chamber and the second expansion chamber are configured such that a portion of the first expansion chamber and a portion of the second expansion chamber overlap.

[0022] In one configuration, the first expansion chamber and the second expansion chamber have different lengths.

[0023] In one embodiment, the resonant chamber is disposed between the first expansion chamber and the second expansion chamber.

[0024] In one embodiment, when the resonant chamber is defined as a first resonant chamber, the muffler structure has a second resonant chamber disposed adjacent to the second expansion chamber.

[0025] The effects of the invention

[0026] According to the above technical solution, the vacuum pump can improve the function of the silencer. Attached Figure Description

[0027] Figure 1 This is a diagram illustrating one embodiment of a vacuum pump.

[0028] Figure 2 This is a diagram showing an example of a pump rotor.

[0029] Figure 3 This is a diagram showing the inlet flow path and the check valve configured in the inlet flow path.

[0030] Figure 4 This is a diagram showing the exhaust flow path formed in the muffler structure.

[0031] Figure 5 This is a diagram showing the thin tubular portion formed between the expansion chamber and the resonance chamber.

[0032] Figure 6 This is a diagram showing the water storage section arranged adjacent to the narrow tube section.

[0033] Figure 7 This is a diagram showing the water storage section arranged adjacent to the narrow tube section.

[0034] Figure 8 This is a diagram showing another embodiment of the muffler structure.

[0035] Figure 9 It means possessing Figure 8 A diagram of a vacuum pump with a silencer structure.

[0036] Symbol Explanation

[0037] 1. Vacuum pump

[0038] 2. Pump rotor

[0039] Rotors 2A and 2B

[0040] 3 Pump casing

[0041] 3A Rotor Housing

[0042] 3B Silencer Reception Section

[0043] 5. Drive motor

[0044] 10. Air intake

[0045] 15. Exhaust pipe

[0046] 15a Fluid Inlet

[0047] 15b Fluid outlet

[0048] 20 Import Flow Path

[0049] 20a small flow path

[0050] 20b Large flow path

[0051] 20c Throttling section

[0052] 30 Check valve

[0053] 31 balls

[0054] 32 Springs

[0055] 40 base plate

[0056] 40a upper surface

[0057] 40b Water storage section

[0058] 50 Muffler Structure

[0059] 55, 56 Thin tubular sections

[0060] 60 Exhaust port

[0061] 100 Exhaust Flow Path

[0062] EC1 and EC2 expansion chambers

[0063] RC1 and RC2 resonant chambers

[0064] L1 and L2 are horizontal widths. Detailed Implementation

[0065] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in the drawings described below, the same or equivalent structural elements are labeled with the same reference numerals, and repeated descriptions are omitted. In the various embodiments described below, the structure of one embodiment is the same as that of the other embodiments unless otherwise specified, and therefore repeated descriptions are omitted.

[0066] Figure 1 This is a diagram illustrating one embodiment of a vacuum pump. (As shown) Figure 1 As shown, the vacuum pump 1 includes: a pair of pump rotors 2 (i.e., rotors 2A and 2B) for compressing gas, a pump housing 3 for housing the pair of pump rotors 2, and a drive motor 5 for rotating the pair of pump rotors 2.

[0067] Figure 2 This is a diagram showing an example of a pump rotor. In Figure 1 and Figure 2 In the illustrated embodiment, the pump rotor 2 is a screw rotor, but the pump rotor 2 is not necessarily limited to a screw rotor. In one embodiment, the pump rotor 2 can be a Roots rotor.

[0068] When driven by the motor 5, a pair of pump rotors 2 rotate in opposite directions via a synchronizing gear (not shown). Through the rotation of the pump rotors 2, gas is drawn into the pump housing 3 through the intake port 10, compressed by the pump rotors 2, and moved downstream. The gas is then discharged to the outside through the exhaust port 60.

[0069] like Figure 1 As shown, the vacuum pump 1 has an exhaust pipe 15 connected to an exhaust port 60. The exhaust pipe 15 has an elbow shape that bends midway and is connected to the lower part of the vacuum pump 1. The exhaust pipe 15 has a fluid inlet 15a connected to the exhaust port 60 and a fluid outlet 15b that opens to the side of the vacuum pump 1.

[0070] As described above, depending on the type of gas discharged from the vacuum pump 1, byproducts are sometimes generated through chemical reactions, and sometimes the gas contains moisture. Even in this case, foreign matter such as moisture and byproducts falls from the exhaust port 60 in the direction of gravity (i.e., vertically downward) and is introduced into the exhaust pipe 15 through the fluid inlet 15a located below the exhaust port 60.

[0071] Foreign matter introduced into exhaust pipe 15 flows through exhaust pipe 15 along with gas and is moved to the outside through fluid outlet 15b. In one embodiment, a branch pipe (not shown), such as a tee, may be connected to fluid outlet 15b. In this case, gas and foreign matter are discharged through different paths. For example, gas flows horizontally, and foreign matter flows vertically downward. Therefore, vacuum pump 1 can operate continuously.

[0072] like Figure 1 As shown, the vacuum pump 1 has a silencer structure 50, which has an exhaust flow path 100 for the gas transferred by the pump rotor 2. The silencer structure 50 is formed in the lower part of the pump housing 3 and has a flat bottom plate 40 forming the bottom of the exhaust flow path 100. (Refer to the following description...) Figure 4 The exhaust flow path 100 is described.

[0073] The pump casing 3 has a rotor housing 3A that houses the pump rotor 2 and a silencer housing 3B disposed below the rotor housing 3A. The rotor housing 3A and the silencer housing 3B are integrally formed. A silencer structure 50 is formed in the silencer housing 3B and disposed below the pump rotor 2. A base plate 40 is mounted on the silencer housing 3B of the pump casing 3.

[0074] From the viewpoint of improving the performance of the vacuum pump 1, the silencer structure 50 has a first structure to prevent malfunction and a second structure to effectively exert the silencing effect. The silencer structure 50 may have at least one of the first and second structures. The structure of the silencer structure 50 will be described below.

[0075] Figure 3 This is a diagram showing the inlet flow path and the check valve configured within it. (Example) Figure 3 As shown, the silencer structure 50 has an inlet flow path 20 for introducing gas transferred by a pair of pump rotors 2 into the exhaust flow path 100. The vacuum pump 1 has a check valve 30 disposed in the inlet flow path 20.

[0076] The check valve 30 has a ball 31 for opening and closing the inlet flow path 20 and a spring 32 for applying force to the ball 31. The inlet flow path 20 has: a small-diameter flow path 20a, a large-diameter flow path 20b, and a throttling flow path 20c disposed between the small-diameter flow path 20a and the large-diameter flow path 20b.

[0077] Ball 31 has a diameter larger than that of the narrow-diameter flow path 20a and is disposed in the throttling flow path 20c. Spring 32 is disposed on the base plate 40 and applies force to ball 31 in the direction away from the base plate 40 (i.e., in the direction of pressing towards the narrow-diameter flow path 20a).

[0078] In this embodiment, ball 31 moves upward via spring 32 during the shutdown of vacuum pump 1, closing the inlet flow path 20. After vacuum pump 1 starts operating, ball 31 moves downward by the pressure of the transferred gas, opening the inlet flow path 20. During operation of vacuum pump 1, check valve 30 prevents backflow of gas.

[0079] The inlet flow path 20 extends vertically downwards as a whole, and the gas flows in the direction of gravity (i.e., vertically downwards). Therefore, foreign matter (byproducts, moisture) contained in the gas does not block the inlet flow path 20 and passes through it.

[0080] In this embodiment, the check valve 30 is arranged vertically along the inlet flow path 20, but the arrangement direction of the check valve 30 is not particularly limited as long as the inlet flow path 20 can be opened and closed using the ball 31. In one embodiment, the check valve 30 may be arranged perpendicular to the inlet flow path 20, i.e., horizontally.

[0081] Figure 4 This is a diagram showing the exhaust flow path formed as a muffler structure. Figure 4 For ease of viewing, the illustration of the base plate 40 is omitted. The flat base plate 40 has a flat upper surface 40a that forms the bottom of the exhaust flow path 100 (see reference). Figure 1 and Figure 3Therefore, the exhaust flow path 100 is a planar flow path formed on the upper surface 40a of the base plate 40.

[0082] With this structure, the exhaust flow path 100 does not have a flow path extending vertically upward, but is formed on the base plate 40. Therefore, the gas flowing in the exhaust flow path 100 does not flow vertically upward, but can always flow horizontally on the base plate 40.

[0083] As a result, the exhaust flow path 100 is not blocked due to the gradual accumulation of foreign matter (byproducts, moisture) contained in the gas. According to this embodiment, the vacuum pump 1 can prevent the silencer structure 50 from malfunctioning due to the gas flowing in the exhaust flow path 100.

[0084] like Figure 4 As shown, the muffler structure 50 includes: expansion chambers EC1 and EC2 forming part of the exhaust flow path 100; resonance chambers RC1 and RC2 connected to the expansion chambers EC1 and EC2; and narrow tubes 55 and 56 connecting the expansion chambers EC1 and EC2 and the resonance chambers RC1 and RC2. Hereinafter, in this specification, the expansion chambers EC1 and EC2 will sometimes be referred to as expansion chamber EC without special distinction. Similarly, the resonance chambers RC1 and RC2 will sometimes be referred to as resonance chamber RC without special distinction.

[0085] The muffler structure 50 has a connecting flow path 51 that connects the inlet flow path 20 and the expansion chamber EC1, and a connecting flow path 52 that connects the expansion chamber EC1 and the expansion chamber EC2. The exhaust flow path 100 is composed of connecting flow paths 51 and 52, expansion chamber EC, resonance chamber RC, and thin tubes 55 and 56, and extends from the inlet flow path 20 to the exhaust port 60.

[0086] like Figure 4 As shown, exhaust port 60 is connected to expansion chamber EC2. Gas passing through exhaust path 100 is transferred to the outside of vacuum pump 1 through exhaust port 60. Figure 1 As shown, the exhaust port 60 is a through hole formed in the base plate 40 and connected to the exhaust pipe 15. The exhaust port 60 extends downwards in the vertical direction, similar to the inlet flow path 20. Therefore, foreign matter contained in the gas does not block the exhaust port 60 but passes through it.

[0087] exist Figure 4 In the illustrated embodiment, the muffler structure 50 has two expansion chambers EC1, EC2 and two resonance chambers RC1, RC2, but the number of expansion chambers EC and resonance chambers RC is not limited to... Figure 4The illustrated embodiment may have a muffler structure 50 having at least one expansion chamber EC and at least one resonance chamber RC. In other words, the muffler structure 50 having an expansion chamber EC and a resonance chamber RC is a combination of an expansion-type muffler and a Helmholtz-type muffler.

[0088] Expansion chamber EC1 has a wider space than connecting flow path 51. Expansion chamber EC2 has a wider space than connecting flow path 52. Expansion chambers EC1 (and EC2) are configured to reduce the pressure of the gas flowing into expansion chambers EC1 (and EC2) from connecting flow path 51 (and connecting flow path 52), thereby attenuating the sound energy and reducing exhaust noise.

[0089] The resonant chambers RC1 (and RC2) reduce exhaust noise by canceling out specific frequencies of sound contained in the exhaust noise of the gas flowing into the resonant chambers RC1 (and RC2) through the thin tube section 55 (and thin tube section 56).

[0090] Expansion chambers EC1 and EC2 have different lengths (dimensions) (see...) Figure 4 Specifically, when comparing the width L1 of expansion chamber EC1 and the width L2 of expansion chamber EC2, the width L1 is smaller than the width L2.

[0091] Additionally, when viewing the muffler structure 50 from the side (from... Figure 4 When viewed in the direction of arrow A, expansion chambers EC1 and EC2 are configured such that a portion of expansion chamber EC1 and a portion of expansion chamber EC2 overlap. This configuration contributes to the compactness of the muffler structure 50 and enables effective reduction of exhaust noise in two stages.

[0092] Resonance chamber RC1 is positioned between expansion chambers EC1 and EC2. Resonance chamber RC2 is positioned adjacent to expansion chamber EC2 along the length of the muffler structure 50 and is aligned in a straight line with expansion chamber EC2. That is, from Figure 4 When viewed in the direction of arrow A, the resonant chamber RC2 is positioned in the space where expansion chambers EC1 and EC2 do not overlap. The connecting flow path 52 bends in a manner that avoids the resonant chamber RC1 to connect expansion chambers EC1 and EC2.

[0093] With this configuration, the muffler structure 50 can effectively arrange multiple expansion chambers EC1, EC2 and multiple resonance chambers RC1, RC2 within the limited space formed by the muffler housing 3B of the pump housing 3. As a result, the vacuum pump 1 has a compact size and can effectively reduce exhaust noise.

[0094] The gas passing through the inlet flow path 20 flows into the expansion chamber EC1 through the connecting flow path 51. At this time, the expansion chamber EC1 reduces exhaust noise. In the space at the end of the expansion chamber EC1, the gas pressure increases. Therefore, from the viewpoint of preventing anti-resonance, the connecting flow path 52 is connected to the middle of the expansion chamber EC1.

[0095] The resonant chamber RC1, connected to the expansion chamber EC1 via the thin tube 55, precisely reduces exhaust noise at specific frequencies. The thin tube 55 is formed by a narrow space on the upper surface 40a of the base plate 40.

[0096] Gas flowing through connecting flow path 52 enters expansion chamber EC2. Expansion chamber EC2 further reduces the exhaust noise reduced in expansion chamber EC1. Gas flowing into expansion chamber EC2 enters resonant chamber RC2 through capillary section 56. Resonant chamber RC2 is configured to cancel out specific frequencies of sound contained in the exhaust noise of the gas. The specific frequencies of sound canceled out by resonant chamber RC2 are different from those canceled out by resonant chamber RC1.

[0097] Figure 5 This is a diagram showing the narrow tubular section formed between the expansion chamber and the resonance chamber. (Example) Figure 5 As shown, the thin tube portion 55 (and the thin tube portion 56) is formed between the expansion chamber EC1 (and the expansion chamber EC2) and the resonance chamber RC1 (resonance chamber RC2).

[0098] When the moisture contained in the gas flowing into the expansion chamber EC condenses, it eventually forms water on the upper surface 40a of the base plate 40. The water accumulation causes a change in the opening area of ​​the capillary section 55 (and capillary section 56).

[0099] Due to this change in the opening area, the resonant frequency of the resonant chamber RC1 (or RC2), which resonates with a specific frequency of the exhaust noise, changes, and the silencing effect produced by the resonant chamber RC1 (or RC2) changes (e.g., decreases). As a result, the vacuum pump 1 produces an operating sound different from that when there is no water accumulation. Furthermore, the accumulation of byproducts generated by the gas also produces the same phenomenon.

[0100] By observing changes in the operating sound generated by the vacuum pump 1, the operator can identify the accumulation of foreign matter such as moisture and byproducts in the muffler structure 50. Therefore, the operator can prevent malfunctions of the muffler structure 50 caused by foreign matter from occurring in advance.

[0101] Figure 6 and Figure 7 This is a diagram showing a water storage section arranged adjacent to the narrow tube section. (Example) Figure 6 and Figure 7As shown, the silencer structure 50 is configured to retain the moisture contained in the gas and has a water storage section 40b formed on the upper surface 40a of the base plate 40. The water storage section 40b is adjacent to the capillary section 55 (and the capillary section 56) and is disposed in the expansion chamber EC1 (and the expansion chamber EC2).

[0102] exist Figure 6 In the illustrated embodiment, the water storage portion 40b has a smoothly curved concave shape. Figure 7 In the embodiment shown, the water storage section 40b has a slit shape. Figure 6 The embodiments shown and Figure 7 The embodiments shown can also be combined. For example, the water storage section 40b can also have a slit shape formed at the bottom of the concave shape.

[0103] The thin tube section 55 (and the thin tube section 56) is, for example, a space with a height of a few millimeters (see reference). Figures 5 to 7 Therefore, when the upper surface 40a is flat, the capillary section 55 (and capillary section 56) may become clogged immediately due to the surface tension of water. Therefore, the water storage section 40b is configured to maintain a constant amount of water. The water storage section 40b can prevent the capillary section 55 (and capillary section 56) from becoming clogged immediately.

[0104] Figure 8 This is a diagram showing another embodiment of the muffler structure. Figure 9 It means possessing Figure 8 A diagram of a vacuum pump with a silencer structure is shown. Figure 8 As shown, the muffler structure 50 can also have a single expansion chamber EC and a single resonant chamber RC connected to the expansion chamber EC. Figure 8 In the embodiment shown, the inlet flow path 20 is connected to one end of the expansion chamber EC via the connecting flow path 51, and the exhaust port 60 is connected to the other end of the expansion chamber EC.

[0105] like Figure 9 As shown, the base plate 40 slopes downwards from the inlet flow path 20 toward the exhaust port 60. Specifically, the base plate 40 has a thickness D2 at one end and a thickness D1 at the other end, with thickness D1 being thinner than thickness D2. Therefore, foreign matter contained in the gas passing through the inlet flow path 20 flows downwards in the exhaust flow path 100 of the muffler structure 50 under the influence of gravity and is discharged into the exhaust pipe 15 through the exhaust port 60. With this structure, the muffler structure 50 can more effectively prevent malfunction caused by blockage of foreign matter.

[0106] The above embodiments are described with the aim of enabling those skilled in the art to implement the present invention. Various modifications of the above embodiments can, of course, be made by those skilled in the art, and the technical concept of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but the technical concept defined by the scope of protection claimed according to the present invention is interpreted in the broadest sense.

Claims

1. A vacuum pump, characterized in that, have: A pair of pump rotors that compress gas; Pump casing, which houses the pair of pump rotors; and A muffler structure having an exhaust flow path for the gas. The muffler structure has a flat base plate that forms the bottom of the exhaust flow path. The exhaust flow path is a planar flow path formed on the base plate.

2. The vacuum pump as described in claim 1, characterized in that, The silencer structure has the following features: An expansion chamber that forms part of the exhaust flow path; A resonant chamber, which is connected to the expansion chamber; and A thin tube section connects the expansion chamber and the resonance chamber.

3. The vacuum pump as described in claim 2, characterized in that, The thin tube section is formed by a space created on the base plate.

4. The vacuum pump as described in claim 3, characterized in that, The silencer structure includes a water storage section for retaining the moisture content in the gas. The water storage section is configured to be adjacent to the thin tube section.

5. The vacuum pump as described in claim 1, characterized in that, The silencer structure has the following features: An inlet flow path is provided for introducing the gas into the exhaust flow path; and An exhaust port that discharges the gas that has passed through the exhaust flow path. The inlet flow path and the outlet extend downwards in the vertical direction, respectively.

6. The vacuum pump as described in claim 5, characterized in that, The base plate is inclined from the inlet flow path toward the exhaust port.

7. The vacuum pump as claimed in claim 1, characterized in that, The vacuum pump includes a check valve configured in the inlet flow path for introducing the gas into the exhaust flow path. The check valve includes: A ball that opens and closes the inlet flow path; and A spring that exerts a force on the ball.

8. A vacuum pump, characterized in that, have: A pair of pump rotors that compress gas; Pump casing, which houses the pair of pump rotors; and A muffler structure having an exhaust flow path for the gas. The silencer structure has the following features: An expansion chamber, which forms part of the exhaust flow path; and A resonance chamber, which is connected to the expansion chamber.

9. The vacuum pump as described in claim 8, characterized in that, When the expansion chamber is defined as the first expansion chamber, the muffler structure has a second expansion chamber. When the muffler structure is viewed from the side, the first expansion chamber and the second expansion chamber are configured such that a portion of the first expansion chamber and a portion of the second expansion chamber overlap.

10. The vacuum pump as claimed in claim 9, characterized in that, The first expansion chamber and the second expansion chamber have different lengths.

11. The vacuum pump as claimed in claim 9, characterized in that, The resonant chamber is positioned between the first expansion chamber and the second expansion chamber.

12. The vacuum pump as claimed in claim 11, characterized in that, When the resonant chamber is defined as the first resonant chamber, the muffler structure has a second resonant chamber disposed adjacent to the second expansion chamber.

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