WO2011039812A1

WO2011039812A1 - Positive displacement dry vacuum pump

Info

Publication number: WO2011039812A1
Application number: PCT/JP2009/005055
Authority: WO
Inventors: 小沢修; 花岡隆; 岩根松美
Original assignee: 樫山工業株式会社
Priority date: 2009-09-30
Filing date: 2009-09-30
Publication date: 2011-04-07
Also published as: TW201111634A

Abstract

A decompression chamber (3) of a positive displacement dry vacuum pump (1) can be communicated with a site (16a) of the suction side of a third-stage pump chamber (16) of a pump body (2) through a second hose (5) and a second vacuum valve (7), and can be communicated with a site (18b) of the exhaust side of a final-stage pump chamber (18) through a first hose (4) and a first vacuum valve (6). During the drive, the second vacuum valve (7) is opened only for a predetermined time period to evacuate the decompression chamber (3), and the first vacuum valve (6) is then opened to evacuate the pump body (2) side using the decompression of the decompression chamber (3), causing the drive load to be reduced. Pump power consumption can be reduced without the need for an auxiliary pump by repeating the evacuation of the decompression chamber (3), and the evacuation of the pump body (2) side using the decompression chamber (3).

Description

Volumetric dry vacuum pump

The present invention relates to a single-stage or multi-stage positive displacement dry vacuum pump, and more particularly to an improved technique for reducing the power consumption without using an auxiliary pump.

Root-type, screw-type and claw-type types are known as volume transfer type dry vacuum pumps. In these positive displacement vacuum pumps, the following three methods are mainly employed in order to reduce power consumption.

In the first method, the pump elements are multistaged, and the exhaust volume of the pump elements is sequentially reduced according to the compression performance of each stage from the intake port side to the exhaust port side. Since the pump element in the final stage placed in the pressure environment on the atmospheric pressure side (exhaust port side) has a smaller power consumption as the exhaust volume of the pump rotor is smaller, the power consumption can be reduced as a whole. This method is disclosed in FIG. 7 to FIG. 13 in the column of the prior art in Patent Document 1 (Japanese Patent No. 4045362).

The second method is to reduce the power consumption of the entire pump by reducing the pressure on the rear stage side (exhaust port side, atmosphere port side) of the pump with a separately prepared auxiliary pump. A method using a mechanical vacuum pump as an auxiliary pump is disclosed in FIGS. A method of reducing the power consumption of the entire pump by reducing the exhaust space in the final stage of the pump by using an ejector pump which is an injection pump instead of the mechanical vacuum pump has been proposed. This method is disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2007-100562).

The former method using a mechanical vacuum pump is advantageous in reducing the power consumption compared to other methods, but it is necessary to prepare another pump, which increases the cost of the vacuum system, and the pump There is a drawback that the necessity of maintenance of itself occurs. Also, in the method of reducing the power consumption of the entire pump by depressurizing the exhaust space in the final stage of the pump using the latter ejector pump, in order to drive the ejector pump separately from the pump system, a predetermined flow rate is required. It is necessary to prepare a compressed driving gas (for example, nitrogen gas).

The third method is to reduce power consumption by controlling the motor current, voltage, and rotation speed in a complex manner corresponding to the load using a pump drive source. This method has a drawback that the control power supply (device) becomes expensive.

Japanese Patent No. 4045362 JP 2007-1000056

SUMMARY OF THE INVENTION An object of the present invention is to provide a positive displacement dry vacuum pump capable of reducing power consumption during operation at low cost and effectively without using an auxiliary pump or a complicated drive control method, and drive control thereof. To propose a method.

In order to solve the above problems, the present invention provides:
The gas sucked from the intake port is transferred to the exhaust port while being compressed via the pump chamber, and is discharged from the exhaust port to the atmosphere side through the exhaust path. In a single-stage positive displacement dry vacuum pump to which a check valve is attached in order to prevent backflow of gas toward the mouth,
A vacuum chamber;
A first communication path having one end communicating with the decompression chamber and the other end communicating with a portion on the exhaust side of the pump chamber;
A second communication path having one end communicating with the decompression chamber and the other end communicating with a portion on the intake side of the pump chamber;
And a switching mechanism that switches each of the first communication path and the second communication path between a communication state and a cutoff state.

When the volume transfer type dry vacuum pump is driven in a state where both the first and second communication paths are held in the shut-off state by the switching mechanism, the suction port side is brought into a predetermined reduced pressure state. After that, when only the second communication path is opened (switched to the communication state), the decompression chamber is evacuated by the pump chamber through the second communication path, and the decompression chamber becomes a predetermined decompression state. Thereafter, when the second communication path is shut off and the first communication path is opened, the exhaust side portion of the pump chamber communicating with the decompression chamber is evacuated by the decompression chamber. By alternately performing evacuation of the decompression chamber by the pump chamber and evacuation of the pump chamber by the decompression chamber, the power consumption of the whole volume transfer type dry vacuum pump can be reduced.

In addition, the multistage type volume transfer type dry vacuum pump to which the present invention is applied,
The gas sucked from the intake port is transferred toward the exhaust port while being sequentially compressed through a plurality of pump chambers connected in series, and is discharged from the exhaust port to the atmosphere side through the exhaust path. In the exhaust passage, a check valve is attached to prevent a back flow of gas from the atmosphere side toward the exhaust port.
A vacuum chamber;
A first communication path having one end communicating with the decompression chamber and the other end communicating with a portion on the exhaust side of the first pump chamber that is one of the plurality of pump chambers;
One end communicates with the decompression chamber, and the other end is one of the pump chambers disposed on the intake side of the first pump chamber or on the inlet side of the first pump chamber. A second communication passage communicating with the suction side portion of the second pump chamber,
And a switching mechanism that switches each of the first communication path and the second communication path between a communication state and a cutoff state.

When the volume transfer type dry vacuum pump is driven in a state where both the first and second communication paths are held in the shut-off state by the switching mechanism, the suction port side is brought into a predetermined reduced pressure state. After that, when only the second communication path is opened (switched to the communication state), the decompression chamber is evacuated by the second pump chamber via the second communication path, and the decompression chamber becomes a predetermined decompression state. Thereafter, when the second communication path is shut off and the first communication path is opened, the exhaust side portion of the first pump chamber communicating with the decompression chamber is evacuated by the decompression chamber. By alternately evacuating the decompression chamber by the first pump chamber and evacuating the first pump by the decompression chamber or evacuating the second pump chamber, the power consumption of the whole volume transfer type dry vacuum pump is reduced. can do.

Here, as the switching mechanism, a first on-off valve inserted in the first communication path and a second on-off valve inserted in the second communication path can be used.

When the first communication path and the second communication path are selectively opened, the switching mechanism includes a first position that opens only the first communication path, a second position that opens only the second communication path, A three-way switching valve that can be switched to a third position that blocks both the first communication path and the second communication path can be used.

Further, in order to prevent the gas from flowing back to the decompression chamber through the second communication passage, the second communication passage is prevented from flowing back to the decompression chamber via the second communication passage. It is desirable that a check valve is attached.

In a multistage positive displacement vacuum pump, the first pump chamber to which the first communication path is connected can be the final pump chamber communicating with the exhaust port. In this case, the first communication passage can be connected to a portion upstream of the check valve in the exhaust passage communicating with the exhaust side of the first pump chamber.

Also in the single-stage positive displacement dry vacuum pump, the first communication path can be connected to the upstream side of the check valve in the exhaust path.

Next, the present invention is a drive control method for a single-stage or multi-stage volumetric transfer type dry vacuum pump configured as described above,
A first step of driving the volume transfer type dry vacuum pump in a state where the first and second communication passages are held in a shut-off state;
After the predetermined decompression state is formed at the intake port, only the second communication path is switched to the communication state, and the decompression chamber is continued for a predetermined time or until the decompression chamber is in the predetermined decompression state. A second step of evacuating
Thereafter, a third step of blocking the second communication path and opening the first communication path;
A fourth pressure reducing the pressure on the discharge side using the pressure difference between the pressure reduction chamber and the discharge side of the first pump chamber (in the case of a single-stage pump). A process,
The second step, the third step, and the fourth step are repeatedly performed.

In the positive displacement vacuum pump of the present invention, a decompression chamber that can be evacuated by a pump body comprising a single-stage or multi-stage pump chamber is attached. After the vacuum chamber is evacuated, the pump body side is evacuated using the vacuum of the vacuum chamber to reduce the driving load. Therefore, power consumption can be reduced with a simple configuration as compared with the case where an auxiliary pump such as a mechanical vacuum pump or an ejector pump is provided. In addition, since it is only necessary to repeatedly switch the decompression chamber and the pump chamber on the pump body side between the communication state and the shut-off state, power consumption can be reduced without requiring complicated drive control.

It is a schematic diagram which shows the structure of the multistage type volume transfer type dry vacuum pump which concerns on embodiment of this invention. (A) is a partial cross-sectional side view showing a partial cross section of the pump body of the multi-stage Roots type dry vacuum pump of FIG. 1, and (b) is a schematic cross-sectional view of a portion cut along the line AA. . It is a graph which shows the characteristic of the power consumption by the roots type dry vacuum pump of FIG. It is a graph which shows the characteristic of the power consumption by the roots type dry vacuum pump of FIG. It is a schematic diagram which shows the structure of the multistage type volume transfer type dry vacuum pump which concerns on the modification of this invention. It is a schematic diagram which shows the structure of the single stage type volume transfer type dry vacuum pump to which this invention is applied.

Embodiments to which the present invention is applied will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the configuration of a multi-stage roots type dry vacuum pump to which the present invention is applied. 2A and 2B are a partial cross-sectional side view showing the pump body in a partial cross section and a schematic cross-sectional view taken along the line AA.

(Description of configuration)
Referring to these drawings, the Roots type dry vacuum pump 1 includes a pump body 2, a decompression chamber 3 attached to the pump body 2, and an airtight connection between the pump body 2 and the decompression chamber 3. The first hose 4 (first communication path) and the second hose 5 (second communication path), the first vacuum valve 6 (first open / close valve) inserted in the first hose 4, and the second hose 5 It has the inserted 2nd vacuum valve 7 (2nd on-off valve). In this example, a check valve 8 is also inserted in the second hose 5.

As shown in FIG. 2, the pump main body 2 includes a cylindrical case 11 having a substantially elliptical cross section. The cylindrical case 11 has one intake side end in the direction of the central axis 2a. An intake port 12 is formed on the outer peripheral surface of 11a, and an exhaust port 13 is formed on the outer peripheral surface of the other exhaust side end portion 11b. Inside the cylindrical case 11, a plurality of pump chambers, in this example, five pump chambers 14 to 18 are formed coaxially from the inlet 12 side to the exhaust port 13 side. Are connected in series. The pump chambers 14 to 18 of each stage constitute an energy-saving pump main body 2 that is arranged so that the exhaust volume gradually decreases from the intake port 12 side to the exhaust port 13 side.

A pair of root rotors R1, R2, R3, R4 and R5 are arranged in each pump chamber 14-18. These roots rotors R1 to R5 are rotationally driven by a motor 19 attached to the end surface of the cylindrical case 11 on the exhaust port side. In the first-stage pump chamber 14, an intake side portion 14 a partitioned by a roots rotor R <b> 1 disposed there communicates with the intake port 12. In the pump chamber 18 of the fifth stage (final stage), an exhaust side portion 18b defined by a roots rotor R5 disposed therein communicates with the exhaust port 13.

The main exhaust pipe 20 (exhaust passage) is connected to the exhaust port 13, and the front end of the main exhaust pipe 20 is opened to the atmosphere side via a check valve 21. The check valve 21 prevents the backflow of gas flowing from the atmosphere side to the exhaust port 13 side. In other words, the check valve 21 is attached so that the direction toward the atmosphere side is the forward direction.

Next, the decompression chamber 3 is a sealed container having a fixed volume, and one ends 4a and 5a of the first hose 4 and the second hose 5 are connected to the decompression chamber 3, respectively. The other end 4b of the first hose 4 communicates with a portion 18b on the exhaust side of the fifth-stage pump chamber 18 (first pump chamber). In this example, the main exhaust pipe 20 communicates with a portion upstream of the check valve 21. When the first vacuum valve 6 inserted in the first hose 4 is opened, the decompression chamber 3 and the exhaust side portion 18b of the fifth-stage pump chamber 18 are in communication with each other, and the first vacuum valve 6 is closed. And between these, it will be in the state interrupted | blocked by the airtight state. The first vacuum valve 6 can be a fluid pressure drive type or an electromagnetic type.

The other end 5b of the other second hose 5 is connected to a portion 18a on the intake side of the fifth-stage pump chamber 18 or a pump chamber 14 to a front-stage side (intake port side) of the fifth-stage pump chamber 18. 17 communicates with a portion on the intake side. In this example, it communicates with the portion 16a on the intake side in the third-stage pump chamber 16 (second pump chamber) which is the middle stage. When the second vacuum valve 7 inserted in the second hose 5 is opened, the decompression chamber 3 and the suction side portion 16a of the third-stage pump chamber 16 are in communication with each other, and the second vacuum valve 7 is closed. And between these, it will be in the state interrupted | blocked by the airtight state. The second vacuum valve 7 can also be a fluid pressure drive type or an electromagnetic type. Further, the check valve 8 inserted in the second hose 5 is located between the end 5b and the second vacuum valve 7, and enters the decompression chamber 3 from the third-stage pump chamber 16 side. The flow of the gas which goes is blocked.

The first and

second vacuum valves

6 and 7 are two-way valves, but a three-way valve can be used instead of these. In this case, only the first hose 6 is opened at the first switching position in the three-way valve, only the second hose 7 is opened at the second switching position, and the first and second hoses 6 are opened at the third switching position. , 7 can be blocked.

(Description of operation)
The operation in the case of evacuating the vacuum vessel 22 indicated by the alternate long and short dash line in FIG. 1 using the multistage roots type dry vacuum pump 1 having this configuration will be described. The exhaust port 22 a of the vacuum vessel 22 is connected to the intake port 12 of the multi-stage roots type dry vacuum pump 1 through the main intake pipe 23. A main vacuum valve 24 is inserted in the main intake pipe 23.

When the motor 19 is driven in a state where the first and

second vacuum valves

6 and 7 are closed, for example, suction is performed through the air inlet 12 at an exhaust speed of 8000 L / min. When the motor 19 is driven and the suction of the gas in the vacuum vessel 22 is started, the sucked gas flows through the pump body 2 from the first-stage pump chamber 14 to the fifth-stage pump chamber 18, and the roots rotor. It is transferred while being compressed by the rotation of R1 to R5. The gas sent to the exhaust-side portion 18 b of the final-stage fifth-stage pump chamber 18 is exhausted to the atmosphere side through the main exhaust pipe 20 and the check valve 21.

At this time, when the second vacuum valve 7 of the second hose 5 capable of communicating between the decompression chamber 3 (for example, the chamber volume 21L) and the third-stage pump chamber 16 of the pump body 2 is opened, an airtight second The gas in the decompression chamber 3 is exhausted through the hose 5 (for example, the inner diameter is 10 mm and the length is 60 cm).

Here, when the vacuum vessel 14 is evacuated, a large amount of gas flows into the suction port 12 of the pump body 2 and temporarily becomes higher in pressure than the decompression chamber 3, so that the gas flows into the third stage pump chamber 16. There is a possibility of backflow from the intake side toward the decompression chamber 3. In this example, the backflow of gas is prevented by the check valve 8 attached to the second hose 5.

By opening the second vacuum valve 7 for a predetermined time (for example, about 30 seconds), the pressure in the decompression chamber 3 is reduced from 101.08 kPa which is atmospheric pressure. When the pressure in the decompression chamber 3 reaches a predetermined decompressed state (for example, when the pressure is reduced to 13.30 kPa), the second vacuum valve 7 is closed.

Next, the first vacuum valve 6 inserted in the first hose 4 (for example, an inner diameter of 10 mm and a length of 60 cm) connecting the exhaust-side portion 18b of the pump final stage and the decompression chamber 3 is opened. The inside of the decompression chamber 3 communicates with the portion 18b on the exhaust side. As a result, the exhaust-side portion 18b is depressurized by the differential pressure between them. By reducing the pressure on the exhaust-side portion 18b, the burden of the work of compressing and transferring the gas in the roots rotor R5 in the fifth-stage pump chamber 18 which is the final stage is greatly reduced.

FIG. 3 is a graph showing an example of the results of experiments conducted by the present inventors using the multi-stage roots type dry vacuum pump 1 having the above-described configuration, and shows the elapsed time and power consumption during energy-saving operation performed during steady operation. It shows a change.

First, the power consumption during steady operation with the standard roots-type dry vacuum pump 1 was 5.78 kW (time points t1 to t2 in FIG. 3).

In this state, the second vacuum valve is opened for approximately 30 seconds (time t2 in FIG. 3), the decompression chamber 3 in the atmospheric pressure state is decompressed to 13.30 kPa, and the second vacuum valve 7 is closed (in FIG. 3). Time t3). At the same time, the first vacuum valve 6 is opened, and the exhaust side portion 18b of the fifth pump chamber 18 of the first final stage is communicated with the decompression chamber 3 (internal pressure: 13.30 kPa) to decompress the exhaust side portion 18b. did. The electric power immediately after depressurization when the first vacuum valve 6 was opened was 1.83 kW, which is about 32% of the electric power in the steady state (time point t4).

If this state is maintained, the gas on the exhaust side of the pump chamber 18 at the final stage flows into the decompression chamber 3, so that the pressure in the decompression chamber 3 increases with time. In this example, the power consumption after 4.4 hours (time t5) was 4.42 kW. This is 77% of the steady state power, and it was confirmed that the energy saving operation is still maintained. That is, the average energy saving effect in one hour was about 50%.

In this example, it was confirmed that it took about 90 minutes for the decompression chamber 3 with a capacity of 21 L to return to the atmospheric pressure (time t6 in FIG. 3). Therefore, it was confirmed that by reducing the pressure of the 21 L decompression chamber 3 to 13.30 kPa, an energy saving operation of about 90 minutes at the maximum can be performed without the need for other power such as an auxiliary pump.

Here, the amount of power required to depressurize the 21 L decompression chamber 3 from atmospheric pressure (101.80 kPa) to 13.30 kPa was about 0.125 kW. In the graph of FIG. 3, S0 indicates the amount of power during steady operation, the hatched portion S1 indicates the power saving amount, and the vertical line portion S2 indicates the amount of increase in power for decompression of the decompression chamber 3.

Note that the amount of power consumption that can be reduced depending on the amount of gas flowing in from the inlet of the pump may differ from the above-mentioned values.

Next, FIG. 4 is a graph showing another example of the experimental results performed by the present inventors using the multi-stage roots type dry vacuum pump 1 having the above-described configuration, and the decompression operation of the decompression chamber 3 is constant after steady operation. It shows changes in elapsed time and power consumption when repeated at intervals of. In this example, the decompression operation of the decompression chamber 3 was performed by switching between opening and closing of the second vacuum valve 7 and the first vacuum valve 6 every 23 minutes. The decompression time of the decompression chamber 3 was 0.25 minutes (15 seconds). In the figure, S0 indicates the amount of power during steady operation, hatched portions S1 (1), S1 (2), S1 (3)... Indicate the power saving amount, and S2 (1) indicates the initial pressure of the decompression chamber 3. The electric power increase amount at the time of exhaust is shown, and S2 (2), S2 (3), S2 (4). As can be seen from FIG. 4, it was confirmed that the energy saving operation of 50% or more can be continued intermittently when the operating power of the standard pump is 100%.

(Modification)
FIG. 5 is a schematic diagram showing a modification of the multi-stage roots type dry vacuum pump 1. The basic configuration of the multi-stage roots type dry vacuum pump 1A is the same as that of the multi-stage roots type dry vacuum pump 1. Accordingly, the corresponding parts are denoted by the same reference numerals, and description of those parts is omitted.

In the multi-stage roots-type dry vacuum pump 1A, the decompression chamber 3 can communicate with a portion 17a on the intake side of the fourth-stage pump chamber 17 via the second hose 5 and the second vacuum valve 7. Also in this case, the effect of reducing power consumption can be obtained as in the case of the multi-stage roots type dry vacuum pump 1 described above.

Here, as a pump chamber communicating with the decompression chamber 3 in order to evacuate the decompression chamber 3, as shown by a broken line in FIG. 4, a portion 14a on the intake side of the first-stage pump chamber 14 or the second stage It may be a portion 15 a on the intake side of the pump chamber 15. Further, in some cases, it may be the intake side portion 18a of the fifth-stage pump chamber 18.

On the other hand, the pump chamber (the connection destination of the first hose 4) to be evacuated by the decompression chamber 3 is not limited to the exhaust-side portion 18b of the fifth-stage pump chamber 18 in the final stage. For example, the exhaust-side portion 17b of the fourth-stage pump chamber 17 can be used. In this case, the second hose 5 is connected to the intake side portion 17a of the fourth-stage pump chamber 17 or the intake-side portions 14a to 16a of the pump chambers 14 to 16 before the fourth stage. That's fine. Similarly, when the connection destination of the first hose 4 is the exhaust-side portion 16b of the third-stage pump chamber 16, the connection destination of the second hose 5 is the intake-side portion of the third-stage pump chamber 16. 16a or the

portions

14a and 15a on the intake side of the

pump chambers

14 and 15 in the preceding stage may be used.

(Other embodiments)
As described above, the embodiment of the present invention has been described by taking the multi-stage root type dry vacuum pump as an example. The method of the present invention for reducing the power consumption of the pump by reducing the pressure in the exhaust side space of the pump using the pressure difference with the decompression chamber is a screw type that is a volume transfer type dry vacuum pump of another type. The present invention can be similarly applied to a claw-type dry vacuum pump, and the same effect can be obtained.

Also, the present invention can be similarly applied to a single-stage positive displacement dry vacuum pump according to each method. FIG. 6 is an explanatory view showing an example of a single-stage roots type dry vacuum pump to which the present invention is applied. The single-stage roots-type dry vacuum pump 1B has the same configuration as that of the multi-stage roots-type dry vacuum pump 1 shown in FIG. 1 except that the pump body 2A includes a single-stage pump chamber 30. Accordingly, in FIG. 6, the corresponding parts are denoted by the same reference numerals.

The roots type dry vacuum pump 1B includes a pump body 2A having a single-stage pump chamber 30, a decompression chamber 3 attached to the pump body 2A, and an airtight first connecting the pump body 2A and the decompression chamber 3. 1 hose 4 (first communication path) and 2nd hose 5 (second communication path), a first vacuum valve 6 (first on-off valve) interposed in the first hose 4, and a second hose 5. And a second vacuum valve 7 (second on-off valve). A check valve 8 is inserted in the second hose 5. A pair of roots rotor R is disposed in the pump chamber 30. The roots rotor R is rotationally driven by a motor 19. In the pump chamber 30, an intake side portion 30 a defined by a roots rotor R disposed therein communicates with the intake port 12, and an exhaust side portion 30 b communicates with the exhaust port 13. A main exhaust pipe 20 (exhaust passage) is connected to the exhaust port 13, and the front end of the main exhaust pipe 20 is opened to the atmosphere side via a check valve 21. The check valve 21 prevents the backflow of gas flowing from the atmosphere side to the exhaust port 13 side.

The decompression chamber 3 is connected to one ends 4a and 5a of the first hose 4 and the second hose 5, respectively. The other end 4 b of the first hose 4 communicates with a portion 30 b on the exhaust side of the pump chamber 30. In this example, the main exhaust pipe 20 communicates with a portion upstream of the check valve 21. When the first vacuum valve 6 inserted in the first hose 4 is opened, the decompression chamber 3 and the exhaust side portion 30b of the pump chamber 30 are in communication with each other, and when the first vacuum valve 6 is closed, these The space is shut off in an airtight state.

The other end 5 b of the other second hose 5 communicates with a portion 30 a on the intake side of the pump chamber 30. When the second vacuum valve 7 inserted in the second hose 5 is opened, the decompression chamber 3 and the portion 30a on the intake side of the pump chamber 30 are in communication with each other, and when the second vacuum valve 7 is closed, these The space is shut off in an airtight state. The check valve 8 inserted in the second hose 5 is located between the end 5b and the second vacuum valve 7, and prevents the flow of gas from the pump chamber 30 toward the decompression chamber 3. To do.

Similarly to the multi-stage type, the single-stage roots-type dry vacuum pump 1B having this configuration also alternately performs vacuuming of the decompression chamber 3 and vacuuming of the site on the exhaust side of the pump chamber 30 by the decompression chamber 3. Thus, power consumption can be reduced.

DESCRIPTION OF

SYMBOLS

1, 1A, 1B Roots type

dry vacuum pump

2, 2A Pump main body 3 Decompression chamber 4

1st hose

4a, 4b End 5

Second hose

5a, 5b End 6 First vacuum valve 7 Second vacuum valve 8 Check valve DESCRIPTION OF SYMBOLS 11 Cylindrical case 12 Intake port 13 Exhaust port 14 1st stage pump chamber 15 2nd stage pump chamber 16 3rd stage pump chamber 17 4th stage pump chamber 18 5th

stage pump chambers

14a, 15a, 16a , 17a,

18a Inlet part

14b, 15b, 16b, 17b, 18b Exhaust part 19 Motor 20 Main exhaust pipe 21 Check valve 22 Vacuum vessel 23 Main intake pipe 24 Main vacuum valve 30 Pump chamber 30a Inlet part 30b Exhaust-side part S0 Electricity amount S1, S1 (1), S1 (2), S1 (3) during steady operation Power saving amount S2, S2 (1), S2 (2), S2 (3), S2 ( 4) Increase in power when evacuating chamber

Claims

The gas sucked from the intake port (12) is transferred toward the exhaust port (13) while being compressed via the pump chamber (30), and the atmosphere is discharged from the exhaust port (13) through the exhaust path (20). A volume transfer type dry vacuum pump in which a check valve (21) is attached to the exhaust passage (20) to prevent backflow of gas from the atmosphere side toward the exhaust port (13). 1B)
A vacuum chamber (3);
A first communication path (4) having one end (4a) communicating with the decompression chamber (3) and the other end (4b) communicating with an exhaust side portion (30b) of the pump chamber (30);
A second communication path (5) having one end (5a) communicating with the decompression chamber (3) and the other end (5b) communicating with a portion (30a) on the intake side of the pump chamber (30);
A volume transfer type dry vacuum comprising a switching mechanism (6, 7) for switching each of the first communication path (4) and the second communication path (5) between a communication state and a blocking state. Pump (1B).
In claim 1,
The switching mechanism includes a first on-off valve (6) inserted in the first communication path (4) and a second on-off valve (7) inserted in the second communication path (5). A volume transfer type dry vacuum pump (1).
In claim 1,
The switching mechanism includes a first position that opens only the first communication path (4), a second position that opens only the second communication path (5), the first communication path (4), and the second communication path ( 5) A volume transfer type dry vacuum pump (1B), characterized in that it is a three-way switching valve that can be switched to a third position that shuts off both.
In claim 1,
A check valve (8) for preventing a back flow of gas toward the decompression chamber (3) through the second communication path (5) is attached to the second communication path (5). A volume transfer type dry vacuum pump (1B).
In claim 1,
The first communication passage (4) communicates with a portion upstream of the check valve (21) in the exhaust passage (20) communicating with the exhaust side of the pump chamber (30). The volume transfer type dry vacuum pump (1B) characterized.
A drive control method for a positive displacement dry vacuum pump (1B) according to any one of claims 1 to 5,
A first step of driving the volume transfer type dry vacuum pump (1, 1A, 1B) in a state where the first and second communication passages (4, 5) are held in a shut-off state;
The second decompression chamber (3) is evacuated by switching only the second communication path (5) to a communication state and evacuating the decompression chamber (3) for a predetermined time or until the decompression chamber (3) is in a predetermined decompression state. Process,
A third step of blocking the second communication path (5) and opening the first communication path (4);
A fourth step of depressurizing the discharge side portion (30b) using a pressure difference between the pressure reduction chamber (3) and the discharge side portion (30b) of the pump chamber (30). ,
A drive control method for a volume transfer type dry vacuum pump (1B), wherein the second step, the third step and the fourth step are repeated.
The gas sucked from the intake port (12) is transferred to the exhaust port (13) while being sequentially compressed through the plurality of pump chambers (14 to 18) connected in series. (13) is discharged to the atmosphere side through the exhaust path (20), and a check valve (21) is provided in the exhaust path (20) in order to prevent a backflow of gas from the atmosphere side toward the exhaust port (13). ) Is attached to the volume transfer type dry vacuum pump (1, 1A),
A vacuum chamber (3);
One end (4a) communicates with the decompression chamber (3), and the other end (4b) is an exhaust side portion (14b) of the first pump chamber (14 to 18) which is one of the plurality of pump chambers. To a first communication path (4) communicating with 18b),
One end (5a) communicates with the decompression chamber (3), and the other end (5b) is located on the intake side of the first pump chamber (14a to 18a) or closer to the intake port than the first pump chamber. A second communication path (5) communicating with an intake side portion (14a to 18a) of a second pump chamber which is one of the plurality of pump chambers disposed in
A volume transfer type dry vacuum comprising a switching mechanism (6, 7) for switching each of the first communication path (4) and the second communication path (5) between a communication state and a blocking state. Pump (1, 1A).
In claim 7,
The switching mechanism includes a first on-off valve (6) inserted in the first communication path (4) and a second on-off valve (7) inserted in the second communication path (5). A volume transfer type dry vacuum pump (1, 1A).
In claim 7,
The switching mechanism includes a first position that opens only the first communication path (4), a second position that opens only the second communication path (5), the first communication path (4), and the second communication path ( 5) A volume transfer type dry vacuum pump (1, 1A), characterized in that it is a three-way switching valve that can be switched to a third position that shuts off both.
In claim 7,
A check valve (8) for preventing a back flow of gas toward the decompression chamber (3) through the second communication path (5) is attached to the second communication path (5). A volume transfer type dry vacuum pump (1, 1A).
In claim 7,
The first pump chamber is a final pump chamber (18) communicating with the exhaust port (13),
The first communication passage (4) communicates with a portion upstream of the check valve (21) in the exhaust passage (20) communicating with the exhaust side of the first pump chamber (18). A volume transfer type dry vacuum pump (1, 1A).
A drive control method for a volume transfer type dry vacuum pump (1, 1A) according to any one of claims 7 to 11,
A first step of driving the volume transfer type dry vacuum pump (1, 1A) in a state in which the first and second communication passages (4, 5) are held in an interrupted state;
The second decompression chamber (3) is evacuated by switching only the second communication path (5) to a communication state and evacuating the decompression chamber (3) for a predetermined time or until the decompression chamber (3) is in a predetermined decompression state. Process,
A third step of blocking the second communication path (5) and opening the first communication path (4);
A fourth step of reducing the pressure on the discharge side portion (18b) using a pressure difference between the pressure reduction chamber (3) and the discharge side portion (18b) of the first pump chamber (18); Have
A drive control method for a volume transfer type dry vacuum pump (1, 1A), wherein the second step, the third step and the fourth step are repeated.