JP2011226367A - Dry vacuum pump device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dry vacuum pump device including a multi-stage root type dry vacuum pump, which can shorten the air discharging time by restricting the lowering of the number of revolution due to an overload by providing an over-compression preventing mechanism for preventing over-compression inside the pump at a proper position.SOLUTION: This dry vacuum pump device including the multi-stage root type dry vacuum pump includes: a final stage outlet port (an outlet port 18) for discharging a gas in the final stage of the multi-stage dry vacuum pump; and an intermediate release outlet port (a pressure release hole 19) at a position where a compression ratio is high. A check valve (an exhaust section check valve 51) is connected to the final stage outlet port (the outlet port 18) so as to release the gas into an atmospheric air region, and an over-compression preventing check valve (an intermediate section check valve 52) is connected to the intermediate release outlet port (the pressure release hole 19) so as to release the gas into the atmospheric region.

Description

  The present invention relates to a dry vacuum pump apparatus provided with a multistage roots type dry vacuum pump, and more particularly to a dry vacuum pump apparatus provided with a multistage roots type dry vacuum pump provided with a mechanism for releasing overcompressed gas.

  In recent years, dry vacuum pumps that can operate from atmospheric pressure and can easily obtain a clean vacuum environment have been used in a wide range of fields such as semiconductor manufacturing facilities. In particular, the manufacture of semiconductor devices consists of more than 300 processes, and the number of vacuum pumps used therein is very large. Therefore, the footprint saving of the vacuum pump device is very important for effective use of the site area in the factory. In particular, since a plurality of vacuum pump devices are often installed side by side in accordance with the width of the vacuum pump device, it is important to reduce the width. As a dry vacuum pump that meets such demands, there is a multi-stage roots type dry vacuum pump.

  When a large-capacity chamber is evacuated with such a multi-stage roots type dry vacuum pump, a large flow of gas flows, and the inside of the pump is overcompressed due to the difference in the exhaust speed of each stage of the pump. As a result, the compression power is increased and the rotational speed control is performed to prevent overload, and the rotational speed is decreased. When the rotational speed decreases, the exhaust speed also decreases. As a result, the evacuation time of the chamber becomes longer, and the semiconductor and liquid crystal device manufacturing lead time becomes longer. As a countermeasure against this, an intermediate discharge outlet is provided in the middle stage of the pump, and an overcompression prevention mechanism is provided for discharging overcompressed gas from the intermediate intermediate outlet and preventing overcompression inside the pump.

JP 2001-289167 A

  In a multi-stage roots type dry vacuum pump, the volume of the first stage rotor chamber is generally determined by the pumping speed of the designed vacuum pump. For this reason, when designing a vacuum pump with a high exhaust speed, it is necessary to increase the volume of the first-stage rotor chamber. On the other hand, the volume of the rotor chamber at the final stage suppresses heat generation (compression heat) due to the pressure difference before and after the rotor chamber at the final stage and the power consumption of the motor that rotates the rotor against the pressure difference. It is necessary to make it smaller. However, if the volume of the rotor chamber at the final stage is reduced, the exhaust cannot be performed smoothly. As described above, since the volume ratio and the heat generation are in a trade-off relationship, it is determined whether to increase or decrease the volume ratio (compression ratio) depending on which point is important to design the vacuum pump. Become. The volume ratio (compression ratio) and the mounting position of the overcompression prevention mechanism are important in reducing the exhaust speed.

  The present invention has been made in view of the above-mentioned points, and an exhaust time can be shortened by providing an over-compression prevention mechanism for preventing over-compression in the pump at an appropriate position and suppressing a decrease in the rotational speed due to overload. It aims at providing the dry vacuum pump apparatus provided with the multistage roots type dry vacuum pump.

  In order to solve the above-mentioned problems, the present invention is a dry vacuum pump apparatus provided with a multi-stage roots type dry vacuum pump, which discharges gas to the final stage of the multi-stage roots type dry vacuum pump, a compression ratio The middle discharge outlet is provided at a high position, a check valve is connected to the final stage discharge opening to the atmosphere area, and an over-compression prevention check valve is connected to the middle discharge outlet to the atmosphere area. It is characterized by.

  Further, the present invention is the above-described dry vacuum pump, wherein the multi-stage root-type dry vacuum pump is a 5-stage root-type dry vacuum pump comprising a 5-stage rotor chamber and a rotor disposed in each stage of the rotor chamber. An outlet is provided in communication with the second-stage rotor chamber, and the axial width of the first-stage rotor is set to be twice or more the axial width of the second-stage rotor.

  Further, the present invention provides the above dry vacuum pump device, wherein the check valve discharge port and the over-compression prevention check valve discharge port are connected to the exhaust flow path, and a silencer is provided in the exhaust flow path, downstream of the silencer. The exhaust passage is connected to the exhaust port of the apparatus and opened to the atmospheric region.

  Further, the present invention is characterized in that, in the dry vacuum pump device, the check valve, the overcompression prevention check valve, the exhaust passage, and the silencer are integrally configured as an exhaust unit.

  In the dry vacuum pump apparatus according to the present invention, the multi-stage roots type dry vacuum pump includes a booster pump and a main pump. The first stage suction port of the main pump is connected to the final stage discharge port of the booster pump, and the exhaust gas is exhausted. The unit is provided in the main pump.

  According to the present invention, the multi-stage roots-type dry vacuum pump is provided with a hollow discharge port at a high compression ratio, and an over-compression prevention check valve is connected to the hollow discharge port and opened to the atmosphere region. A decrease in the number of rotations due to the load can be suppressed, and the exhaust time can be shortened.

  According to the present invention, the multi-stage root-type dry vacuum pump is a 5-stage root-type dry vacuum pump, in which the hollow discharge port is provided in communication with the second-stage rotor chamber, and the axial width of the first-stage rotor. Is set to more than twice the axial width of the second stage rotor, the compression ratio of the second stage rotor chamber is high, and over-compression prevention is reversed at the hollow discharge port communicating with the second stage rotor chamber. By connecting the stop valve and opening it to the atmosphere, it is possible to effectively suppress a decrease in the rotational speed due to an overload and to shorten the exhaust time.

  Further, according to the present invention, the discharge port of the check valve and the discharge port of the overcompression prevention check valve are connected to the exhaust flow path, the silencer is provided in the exhaust flow path, and the exhaust flow path on the downstream side of the silencer Is connected to the apparatus exhaust port, so that the noise of the gas discharged from the final discharge port and the noise of the overcompressor body discharged from the hollow discharge port can be silenced (reduced).

  Further, according to the present invention, the check valve, the over-compression check valve, the exhaust flow path, and the silencer are integrally configured as an exhaust unit, so that the number of parts of the exhaust system of the dry vacuum pump can be reduced and the size can be reduced. Thus, the entire apparatus can be reduced in size and cost.

It is a figure which shows the longitudinal cross-section of the multistage roots type dry vacuum pump with which the dry vacuum pump apparatus which concerns on this invention is provided. It is a figure which shows the cross-sectional structure of the multistage roots type dry vacuum pump of FIG. It is a figure which shows the axial direction width dimension of each rotor of a multistage root type dry vacuum pump. It is a figure which shows the flow sheet of the dry vacuum pump apparatus which concerns on this invention. It is a figure for demonstrating the structure of an exhaust unit. It is a top view which shows the cross-section of an exhaust unit. It is a front view which shows the cross-section of an exhaust unit. It is a figure which shows the structure of the silencer part of an exhaust unit. It is a figure which shows the flow sheet of the dry vacuum pump apparatus which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described in detail. First, a multi-stage roots type dry vacuum pump provided in a dry vacuum pump apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view showing the overall configuration of a multi-stage roots type dry vacuum pump, and FIG. 2 is a sectional view taken along line AA in FIG. The multi-stage roots-type dry vacuum pump 10 is a five-stage pump, and a pair of five-stage root-type rotors 12a, 12b, 12c, 12d, and 12e are fixed to two rotating shafts 11a and 11b, respectively. The rotary shafts 11a and 11b are rotatably supported by bearings 20 and 21, respectively. In the following description, the pair of rotors 12a, 12b, 12c, 12d, and 12e are collectively referred to as rotors 12 and 12 as appropriate.

  Minute gaps are formed between the rotors 12 and 12 and between the rotors 12 and 12 and the inner peripheral surface of the rotor casing 14, and the rotors 12 and 12 are not centered on the respective rotation shafts 11a and 11b. It is designed to rotate by contact. Rotor chambers 13a, 13b, 13c, 13d, and 13e that accommodate the rotors 12a, 12b, 12c, 12d, and 12e, respectively, and transfer gas, respectively, have one rotor casing 14 in series along the two rotation shafts 11a and 11b. Is placed inside. A cover member (not shown) is attached to the upper surface of the rotor casing 14. A suction port 17 is formed in the upper part of the rotor casing 14, and the suction port 17 communicates with the first-stage rotor chamber 13 a. A first side casing 26 is fixed to the discharge port side surface of the rotor casing 14, and a bearing casing 23 is fixed to the side surface of the side casing 26. In the side casing 26, a discharge port 18 communicating with the rotor chamber 13e at the final stage is formed. As will be described in detail later, the discharge port 18 discharges gas to the atmosphere through an exhaust check valve and a silencer.

  As shown in FIG. 1, a motor (for example, a brushless DC motor) 22 is disposed on the left side of the bearing 20 in the drawing. That is, the motor rotor 22a is fixed to one end of the rotary shafts 11a and 11b, and the motor stator 22b is disposed around the motor rotor 22a. The motor 22 is supplied with variable frequency power by a power supply device such as an inverter device (not shown), and controls the rotation speed of the vacuum pump including soft start. The motor 22 is disposed inside the motor casing 24. When a brushless DC motor is adopted as the motor 22, the rotors 12 and 12 are synchronously reversed by the brushless DC motor 22 via the rotating shafts 11a and 11b. The timing gear 29 and the discharge-side bearing 21 are accommodated in a bearing casing 23 at the other end of the rotary shafts 11a and 11b, respectively. The bearings 20 and 21 are respectively held by bearing cases 40 and 41, and these bearing cases 40 and 41 are accommodated in the motor casing 24 and the bearing casing 23, respectively.

  In each of the rotor chambers 13a to 13e, the gas trapped between the rotors 12 and 12 fixed to the two rotary shafts 11a and 11b and the inner peripheral surface of the rotor casing 14 is transferred from the suction side to the discharge side. Is done. The rotor casing 14 is a double casing, and gas flow paths 15a, 15b, 15c, 15d, and 15e are provided between the inner and outer peripheral walls constituting the double casing. The discharge side of the rotor chamber 13a and the suction side of the rotor chamber 13b at the next stage communicate with each other by a gas flow path 15a, and the gas compressed by the rotor 12a in the rotor chamber 13a passes through the gas flow path 15a and the rotor chamber 13b. It is transferred to the suction side. In this way, the gas compressed by the rotors 12, 12 of each stage is sequentially transferred to the discharge side through the gas flow paths 15 a to 15 e and transferred to the discharge port 18.

  In general, in a multi-stage roots type dry vacuum pump, the volume of the first stage rotor chamber is determined by the pumping speed of the designed vacuum pump. For this reason, when designing a vacuum pump with a high exhaust speed, it is necessary to increase the volume of the first-stage rotor chamber. On the other hand, the volume of the rotor chamber at the final stage suppresses heat generation (compression heat) due to the pressure difference before and after the rotor chamber at the final stage and the power consumption of the motor that rotates the rotor against the pressure difference. It is necessary to make it smaller. However, if the volume of the rotor chamber at the final stage is reduced, the exhaust cannot be performed smoothly. As described above, since the volume ratio and the heat generation are in a trade-off relationship, it is determined whether to increase or decrease the volume ratio (compression ratio) depending on which point is important to design the vacuum pump. Become. Here, the width dimension in the axial direction of the first-stage rotor chamber 13a is at least twice the width dimension of the second-stage rotor chamber 13b. That is, as shown in FIG. 3, the width dimension in the axial direction of the first stage rotor 12a is set to be twice or more the width dimension of the second stage rotor 12b. Then, the third-stage rotor 12c, the fourth-stage rotor 12d, and the fifth-stage rotor 12e are sequentially reduced in axial width by a predetermined ratio.

  When a brushless DC motor is adopted as the motor 22, by controlling the rotational speed of the motor 22, the exhaust speed can be increased while the volume of the rotor chamber 13e at the final stage is reduced, and the heat generation and the motor power consumption are reduced. Can be suppressed. That is, as compared with a conventional vacuum pump using a normal motor, the volume ratio (compression ratio) can be increased while achieving the same exhaust speed, and the heat generation amount can be suppressed. Further, by using the brushless DC motor 22 as described above as a drive source for rotationally driving the two rotary shafts 11a and 11b, not only the efficiency as a motor is good, but also a large load fluctuation can be dealt with. It is also possible to cope with an increase in compression power at the time of startup.

  A bearing 21 is disposed in the vicinity of the discharge port 18 of the dry vacuum pump, and rotatably supports the rotary shafts 11a and 11b together with the bearing 20 on the suction side. The bearing 21 is accommodated in a bearing casing 23, and a side casing 26 is disposed between the bearing casing 23 and the rotor casing 14. An O-ring seal (seal part) (not shown) is disposed between the bearing casing 23 and the side casing 26, thereby sealing a minute gap between the bearing casing 23 and the side casing 26. Further, an O-ring seal (seal part) (not shown) is also disposed between the side casing 26 and the rotor casing 14, thereby sealing a minute gap between the side casing 26 and the rotor casing 14. The bearing 20 is accommodated in a motor casing 24, and a second side casing 30 is disposed between the motor casing 24 and the rotor casing 14. An O-ring seal (seal part) (not shown) is disposed between the side casing 30 and the rotor casing 14. Further, an O-ring seal (seal part) (not shown) is disposed between the side casing 30 and the motor casing 24.

  In the dry vacuum pump having the above-described configuration, when the motor 22 is started and the rotary shafts 11a and 11b are rotated, the rotors 12a, 12b, 12c, 12d, and 12e rotate, and the gas sucked from the suction port 17 becomes the rotor chamber 13a. , 13b, 13c, 13d, and 13e, compressed by the rotors 12a, 12b, 12c, 12d, and 12e, sequentially transferred to the discharge side through the gas flow paths 15a to 15e, and discharged from the discharge port 18 to the atmospheric compression region Is done. An exhaust unit 50 is connected to the discharge port 18, and the gas discharged from the discharge port 18 is discharged through the exhaust unit 50. The exhaust unit 50 is provided with an exhaust check valve (final check valve) 51, an intermediate check valve 52 with a second-stage outlet hollowed out, and a silencer 53. The intermediate check valve 52 releases the gas in which the gas in the dry vacuum pump is compressed to the external pressure or more into the outside air, and the pressure relief hole 19 (see FIG. 4) provided to suppress the power loss of the dry vacuum pump. This is an overcompression prevention valve provided in the reference).

  FIG. 4 is a view showing a flow sheet of the dry vacuum pump 10 and the exhaust unit 50. As shown in the drawing, when the multi-roots type dry vacuum pump 10 is operated, the gas sucked into the suction port 17 flows into the exhaust unit 50 from the discharge port 18 through the gas flow paths 15a to 15e, and the exhaust check valve (final) It is discharged to the outside (atmosphere region) through a stage check valve 51 and the silencer 53. Further, when the inside of the dry vacuum pump 10 is overcompressed, such as when the dry vacuum pump 10 is started up, an exhaust unit is connected to the gas flow path 15b (communication with the second-stage rotor chamber 13b) through a pressure relief hole 19 The gas flowing into the gas 50 is sent to the silencer 53 through an intermediate check valve (overcompression prevention check valve) 52. As will be described in detail later, the exhaust check valve 51, the intermediate check valve 52, and the silencer 53 are integrally disposed in the exhaust unit 50, and by attaching the exhaust unit 50 to the dry vacuum pump 10, The exhaust check valve 51, the intermediate check valve 52, and the silencer 53 can be attached to the dry vacuum pump 10.

  FIG. 5 is a diagram for explaining the structure of the exhaust unit 50. As described above, the dry vacuum pump 10 is provided with the rotor chambers 13a, 13b, 13c, 13d, and 13e. Although not shown, rotors 12a, 12b, 12c, 12d, and 12e are arranged as shown in FIG. The gas compressed in each rotor chamber of the dry vacuum pump 10 and discharged from the discharge port 18 communicating with the rotor chamber 13e at the final stage passes through the gas flow path 54 provided in the exhaust unit 50, and the reverse of the exhaust section. The gas that flows into the stop valve 51 and exits from the exhaust check valve 51 is sent to the silencer 53 through the gas flow path 56 provided in the exhaust unit 50. Further, the pressure relief hole 19 that communicates with the second stage rotor chamber 13b of the dry vacuum pump 10 communicates with the intermediate check valve 52 through the gas passage 55 provided in the exhaust unit 50, so that the dry vacuum When the inside of the pump 10 is overcompressed, the overcompressed gas passes through the intermediate check valve 52 and is sent from the gas flow path 56 to the silencer 53.

  FIG. 6 is a diagram showing the configuration of the exhaust unit 50, and FIG. 6 (a) is a plan view of the plan view 6 (b). The exhaust unit 50 includes a valve unit 50a and a silencer unit 50b. An exhaust check valve 51 and an intermediate check valve 52 are arranged in the valve portion 50a. As shown in FIG. 5, the inlet portion of the exhaust check valve 51 communicates with the discharge port 18 through the gas passage 54, and the inlet portion of the intermediate check valve 52 passes through the gas passage 55. It communicates with the pressure relief hole 19 through. The discharge ports of the exhaust check valve 51 and the intermediate check valve 52 communicate with the gas flow path 56. Moreover, the gas flow path 56 is connected to the gas flow path 61 of the silencer part 50b.

  FIG. 7 is a diagram showing the configuration of the silencer 53 in the silencer 50b. Fig.7 (a) is a figure which shows the side cross-section structure of this silencer, FIG.7 (b) is AA sectional drawing. This silencer 53 is a composite silencer in which a resonance type silencer 53-1 and an expansion type silencer 53-2 are integrally formed, and a wall 70 is provided between the resonance type silencer 53-1 and the expansion type silencer 53-2. Intervene. The resonance-type silencer 53-1 and the expansion-type silencer 53-2 are provided in communication with a gas flow path 61 that communicates with a gas flow path (not shown) of the exhaust unit 50. In addition, the expansion type silencer 53-2 is arranged on the downstream side.

  The silencer 53 includes a thick plate-like silencer casing 60 and a lid 69. On one side surface of the silencer casing 60, a groove-like gas flow channel 61 having an upper opening communicating with the gas flow channel 56, a concave resonance chamber 62 having an upper opening constituting the resonance silencer 53-1, an expansion silencer 53, and the like. A concave first expansion chamber 63 and a second expansion chamber 64 which are open at the upper part constituting -2 are formed. Further, a groove-shaped resonance port 65 having an upper opening communicating with the resonance chamber 62 and the gas flow path 61, a groove-shaped first throttle port 66 having an upper opening communicating with the first expansion chamber 63 and the gas flow path 61, A second throttle port 67 having an open upper portion communicating with the first expansion chamber 63 and the second expansion chamber 64 and a third throttle port 68 communicating with the second expansion chamber 64 and the outside are provided.

  The surface of the silencer casing 60 on which the gas flow path 61, the resonance chamber 62, the first expansion chamber 63, the second expansion chamber 64, and the like are formed is covered with a lid 69, so that the gas flow path 61 and the resonance chamber 62 are covered. The first expansion chamber 63 and the second expansion chamber 64 are spaces in which the upper opening is closed. The resonance chamber 62 and the first expansion chamber 63 whose upper opening is closed communicate with the gas flow path 61 through the resonance port 65, respectively. The first expansion chamber 63 and the second expansion chamber 64 whose upper opening is closed are the second throttle. The second expansion chamber 64 communicates with the outside through the third throttle port 68.

  The silencer 53 is a composite having a configuration in which the resonance silencer 53-1 and the expansion silencer 53-2 are integrally formed on the thick silencer casing 60 as described above, and the opening is closed by the lid 69. Type silencer. Further, since the silencer 53 is constituted by the thick plate-like silencer casing 60 and the lid body 69, the silencer is flat and miniaturized. The noise of the gas flow that has flowed into the gas flow path 61 from the gas flow path of the exhaust unit 50 resonates with the natural frequency of the resonance type silencer 53-1 including the resonance port 65 and the resonance chamber 62 and is reduced (reduced). ) The gas flow that has passed through the resonance type silencer 53-1 flows into the first expansion chamber 63 through the first throttle port 66, and is expanded and silenced (reduced) in the first expansion chamber 63. By flowing into the second expansion chamber 64 through the second restrictor 67, the sound is expanded and silenced (reduced) in the second expansion chamber 64, and further flows out to the outside air through the third restrictor 68 and expands to silence. (Reduced).

  The resonance silencer 53-1 can be reduced in size and has a feature that the flow of gas flowing through the gas flow path 61 is not obstructed, but the frequency range of noise that can be silenced is narrower than that of the expansion type. In contrast, the expansion silencer 53-2 can mute noise in a wide frequency range, but the frequency that can be muffled is inversely proportional to the length of the silencer. Therefore, when silencing in the low frequency range, the silencer becomes longer. End up. Therefore, by reducing the noise in the low frequency region of the gas flow with the resonance type silencer 53-1, which can be reduced in size, and reducing the noise in the remaining high frequency region with the expansion silencer 53-2 in which the length of the silencer is inversely proportional to the silence frequency, Both the resonance type silencer 53-1 and the expansion type silencer 53-2 are reduced in size, and the entire silencer 53 can be reduced in size, and noise can be silenced (reduced) in a wide frequency band.

  Further, since the resonance type silencer 53-1 is provided on the upstream side of the gas flow path 61, the resonance type silencer 53-1 has a feature that does not hinder the flow of the gas flowing into the gas flow path 61. Even if such a complex silencer is provided on the gas discharge side of the gas flow path of the exhaust unit 50, the gas discharge function of the exhaust unit 50 can be reduced and suppressed as much as possible.

  The valve unit 50a and the silencer unit 50b of the exhaust unit 50 are configured integrally, and are configured as one component that configures the dry vacuum pump device. Accordingly, parts such as piping for connecting the exhaust check valve 51 to the discharge port 18 of the dry vacuum pump 10, parts such as piping for connecting the intermediate check valve 52 to the pressure relief hole 19, and a silencer part Parts such as piping for connecting to the gas flow path 61 of the 50b and the gas flow path 56 of the valve 50a are unnecessary, the number of parts for constituting the exhaust part of the dry vacuum pump 10 is reduced, and the cost is also reduced. .

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Can be modified. For example, as shown in the flow sheet of FIG. 8, a multi-stage root-type dry vacuum pump 10-2 is provided as the main pump MP, a multi-stage root-type dry vacuum pump 10-1 is provided as the booster pump BP, and the suction port 17 of the main pump MP is provided. Connected to the discharge port 18 of the booster pump BP, the exhaust unit 50 is mounted on the main pump MP, the discharge port 18 of the main pump MP is connected to the exhaust check valve 51, and the pressure relief hole 19 is connected to the intermediate check valve 52. Make it connected.

  In the present invention, a multi-stage roots-type dry vacuum pump is provided with a hollow discharge port at a high compression ratio, and an over-compression check valve is connected to the hollow discharge port and opened to the atmosphere region. It can be used as a dry vacuum apparatus equipped with a multi-stage roots type dry vacuum pump capable of suppressing a decrease in the number of rotations and shortening the exhaust time.

DESCRIPTION OF SYMBOLS 10 Dry vacuum pump 11a Rotating shaft 11b Rotating shaft 12 Rotor 12a-12e Rotor 13a-13e Rotor chamber 14 Rotor casing 15a-15e Gas flow path 17 Suction port 18 Discharge port 19 Pressure relief hole 20 Bearing 21 Bearing 22 Motor 22a Motor rotor 22b Motor Stator 23 Bearing casing 24 Motor casing 26 Side casing 29 Timing gear 30 Side casing 40 Bearing case 41 Bearing case 50 Exhaust unit 51 Exhaust check valve 52 Intermediate check valve 53 Silencer 53-1 Resonant silencer 53-2 Expansion type Silencer 54 Gas flow channel 55 Gas flow channel 56 Gas flow channel 60 Silencer casing 61 Gas flow channel 62 Resonance chamber 63 First expansion chamber 64 Second expansion chamber 65 Resonance port 66 First throttle port 67 Second throttle Opening 68 Third throttle 69 Cover
70 walls

Claims (5)

A dry vacuum pump device equipped with a multi-stage roots type dry vacuum pump,
The final stage discharge port for discharging gas to the final stage of the multi-stage roots type dry vacuum pump, and a hollow discharge port at a position with a high compression ratio,
Connect a check valve to the final stage outlet and open it to the atmosphere,
A dry vacuum pump device characterized in that an overcompression check valve is connected to the hollow discharge port and is opened to the atmosphere. The dry vacuum pump according to claim 1,
The multi-stage root-type dry vacuum pump is a 5-stage root-type dry vacuum pump provided with a 5-stage rotor chamber and a rotor disposed in each stage of the rotor chamber.
The hollow discharge port is provided in communication with the second-stage rotor chamber,
The dry vacuum pump device characterized in that the axial width of the first-stage rotor is set to be twice or more the axial width of the second-stage rotor. In the dry vacuum pump device according to claim 1 or 2,
The discharge port of the check valve and the discharge port of the overcompression check valve are connected to an exhaust flow path, a silencer is provided in the exhaust flow path, and the exhaust flow path on the downstream side of the silencer is connected to the apparatus exhaust port A dry vacuum pump device characterized by being opened to the atmosphere. In the dry vacuum pump device according to any one of claims 1 to 3,
A dry vacuum pump device, wherein the check valve, the overcompression prevention check valve, the exhaust passage, and the silencer are integrally configured as an exhaust unit. In the dry vacuum pump device according to claim 4,
The multi-stage roots type dry vacuum pump is composed of a booster pump and a main pump, the first-stage suction port of the main pump is connected to the final-stage discharge port of the booster pump, and the exhaust unit is provided in the main pump. A dry vacuum pump device characterized by

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