JP2008088880A - Evacuation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evacuation apparatus improving evacuation speed to a low vacuum area from atmospheric pressure and improve evacuation speed in all pressure areas from atmospheric pressure to high vacuum condition in evacuation devices provided with a booster pump and a back pump on an atmospheric pressure side on a downstream side thereof in series and evacuating inside of a chamber, a tank or the like. <P>SOLUTION: This apparatus is provided with the booster pump 5 and the back pump 3 on the atmospheric pressure side on the downstream side in series. The booster pump 5 includes low compression delivery ports 27a, 27b delivering at a stage of low compression ratio in a process of compression in a pump chamber and a high compression delivery port 29 delivering after reaching high compression ratio, evacuates air from the high compression delivery port 29 to atmospheric pressure by operating the booster pump 5 in start of evacuation, and supplies delivery air from the low compression delivery ports 27a, 27b and starts operation of the back pump 3 when it reaches a middle vacuum condition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vacuum evacuation apparatus that is provided with a booster pump and a back pump in series on the downstream side of the atmosphere to vacuum a tank, a room, and the like.

  Conventionally, a vacuum mechanical booster pump is installed and used on the vacuum side of a back pump having a low exhaust speed in order to increase the exhaust speed and quickly bring the tank, the room, and the like into a vacuum state. As a vacuum mechanical booster pump, a roots-type vacuum pump 021 that compresses and exhausts by rotating an eyebrows-shaped rotor 020 as shown in FIG. 5 is generally used. And it is known that the maximum exhaust speed about several times the exhaust speed of the back pump is obtained by using this mechanical booster pump.

However, even if a large amount of air is sent to the back pump installed on the downstream atmosphere side by this mechanical booster pump, the exhaust speed of the back pump limits the exhaust speed of the entire device, so the mechanical booster pump is near atmospheric pressure. Even if it is operated in the low vacuum region, the effect of improving the exhaust speed cannot be greatly obtained.
That is, as shown in the relationship between the exhaust speed and the pressure in FIG. 3, at the start of discharging atmospheric air, the exhaust speed due to the function of the mechanical booster pump from the exhaust speed inherent in the back pump. This improvement effect cannot be obtained immediately and tends to increase as the degree of vacuum progresses, and the improvement effect of the exhaust speed cannot be obtained in the entire pressure region.

On the other hand, there is known a vacuum exhaust apparatus in which a booster pump such as a vacuum mechanical booster pump is installed in front of a vacuum pump and exhausted by a two-stage vacuum pump in series. (Patent Document 1).
As shown in FIG. 6, this Patent Document 1 is connected to a roughing line A for roughing air from a chamber and a main pulling line B for performing main pulling. The stop valve 03a and the butterfly valve 04 are connected in series, and further connected to the roughing pump 01. The main drawing line B is provided with stop valves 03b1 and 03b2 and an exhaust pump 02. When performing the main pulling, the stop valve 03a and the butterfly valve 04 in the roughing line A are closed, the stop valves 03b1 and 03b2 in the main pulling line B are opened, and the main pulling in the chamber is performed by the roughing pump 01 and the exhaust pump 02. A configuration for performing is shown.

  Further, assuming that the vacuum pump is installed in two stages, an auxiliary pump 012 is connected to the intermediate stage or the final stage 011 of the multi-stage R1 to R6 dry vacuum pump 010 as shown in FIG. In order to reduce the power consumption, there is known (Patent Document 2).

No. 7-19554 Japanese Patent Laid-Open No. 2003-155988

However, Patent Document 1 cannot exhaust the exhaust speed because it is exhausted only by the roughing pump 01 at the time of roughing, and further exhausts at two stages of the roughing pump 01 and the exhaust pump 02 at the time of the main pulling. Control of the operation of the exhaust pump 02 arranged in the preceding stage is not shown, and the exhaust speed is improved even in the low pressure range from the atmospheric pressure to the exhaust speed in all pressure ranges from the low vacuum state to the high vacuum state. There is a problem as to whether improvement is achieved.
Further, the auxiliary pump 012 shown in Patent Document 2 is intended to reduce the power consumption of the dry vacuum pump 010 and is not shown for improving the exhaust speed.

  Therefore, the present invention has been made in view of such a background. In a vacuum evacuation apparatus in which a booster pump and a back pump are provided in series on the downstream side of the atmosphere so that a tank, a room, and the like are in a vacuum state, It is an object of the present invention to provide an evacuation apparatus that improves the evacuation speed even in the low pressure region from the atmospheric pressure and improves the evacuation speed in all pressure regions from the atmospheric pressure to the high vacuum state.

  In order to solve the above-mentioned problems, the invention according to claim 1 is the vacuum pumping device comprising a booster pump and a back pump on the downstream side of the air in series to vacuum the tank, the room, etc., and the booster pump Has a low compression discharge port that discharges at a low compression ratio in the process of being compressed in the pump chamber, and a high compression discharge port that discharges after reaching a high compression ratio. The gas is exhausted from the high-compression discharge port to the atmosphere, and when the medium vacuum state that can be reached by discharge from the high-compression discharge port is reached, the discharge gas from the low-compression discharge port is A controller for supplying the back pump and operating the back pump is provided.

According to this invention, the booster pump is operated at the beginning of exhaust to exhaust the gas from the high compression discharge port to the atmosphere. As a result, the gas in the tank at atmospheric pressure is compressed by a high compression ratio and directly discharged to the atmosphere. At this time, since the exhaust is performed directly without going through the back pump, the exhaust can be performed without being affected by the back pump. For example, the pumping speed can be improved without using a large pump to increase the pumping speed of the back pump.
In addition, since the pumping speed of the booster pump is higher than that of the back pump, the pumping speed of the booster pump is large, so that the pumping speed is reduced without reducing the pumping speed from the initial state of exhausting in the atmospheric state. it can. And the exhaust speed can be improved even in a low vacuum region from atmospheric pressure.

When the medium vacuum state that can be reached by discharge from the high compression discharge port of the booster pump is reached, the discharge gas from the low compression discharge port is supplied to the back pump and the back pump is operated. As a result of the caulking, the medium vacuum gas that has been in a certain vacuum state is supplied to the back pump from the low compression outlet. Then, the pumping speed of the back pump is increased by pressurization and increasing action by the booster pump, and a high vacuum state can be reached while maintaining a high pumping speed.
Therefore, the pumping speed is improved by the booster pump even from the atmospheric pressure to the low vacuum region, and the exhausting speed is improved in all pressure regions from the atmospheric pressure to the high vacuum state.

  In a preferred embodiment, the controller detects the arrival of the medium vacuum state by the passage of time by a timer.

  According to this invention, when a predetermined time has elapsed from the start of exhaust by the booster pump, the controller automatically supplies the discharge gas from the low compression discharge port to the back pump and activates the back pump. Thus, the operation to the back pump is automatically controlled. Furthermore, since control is performed not by a signal from the pressure sensor but by an elapsed time by a timer, it is possible to perform highly reliable control without the risk of deterioration or malfunction of the pressure sensor.

  Preferably, the booster pump is a claw-type vacuum pump, the high compression discharge port is opened in a housing wall surface in the rotation axis direction of the rotor, and the low compression discharge port is formed in a housing wall surface in the radial direction of the rotor. It is formed by opening.

  According to this invention, the high compression discharge port is formed to open on the housing wall surface in the rotation axis direction of the rotor so as to face the space of the compression chamber of the claw type vacuum pump, and the low compression discharge port is further formed on the radius of the rotor. By forming it in the housing wall surface in the direction, a booster pump having a high compression discharge port and a low compression discharge port can be formed using a claw type vacuum pump.

  According to the present invention, in a vacuum evacuation device that is provided with a booster pump and a back pump in series on the downstream side of the atmosphere so that the tank, the room, etc. are in a vacuum state, the evacuation speed is improved even in a low vacuum region from atmospheric pressure. Further, it is possible to provide a vacuum exhaust apparatus in which the exhaust speed is improved in all pressure regions from the atmospheric pressure to the high vacuum state.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Only.

FIG. 1 is an overall configuration diagram according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG.
As shown in FIG. 1, the vacuum evacuation device 1 includes a back pump 3 and a booster pump 5 provided at the front stage of the back pump 3. By operating both the pumps 3 and 5, a vacuum tank 7 is provided. The inside is configured to be in a vacuum state.

  The booster pump 5 includes a claw-type vacuum pump 9 and includes a pair of pump rotors 11a and 11b, an air suction port 13, and an air discharge port 15, and further includes a pair of pump rotors 11a and 11b. A pump casing 17 (housing) and a drive mechanism that transmits power from a motor of a power source (not shown) and rotationally drives the pump rotors 11a and 11b around the rotary shaft 19 are provided. The type of the back pump 3 is not limited as long as it is a vacuum pump, and any type of pump such as a root type, a claw type, a screw type, or a gear type may be used.

The pump rotors 11a and 11b are sucked and discharged using the volume change of the sealed space formed in the pump casing 17 by being rotated in opposite directions (arrow S direction) by the drive mechanism. .
The pump rotors 11a and 11b are respectively provided with projections 21a and 21b such as claws, and the mating projections 21a and 21b are fitted into the recesses 23a and 23b. A space for the compression chamber 25 is formed.

The air discharge port 15 has a low compression discharge port 27 that discharges at a stage of a low compression ratio in the process of being compressed in the pump chamber, and a high compression discharge port 29 that discharges after reaching a high compression ratio. The low-compression discharge port 27 is opened at a position where air sucked from the air suction port 13 is discharged before being pushed into the space of the compression chamber 25 formed by the pump rotors 11a and 11b. The first low-compression discharge port 27a corresponding to the pump rotor 11a and the second low-compression discharge port 27b corresponding to the pump rotor 11b are provided.
The first low-compression discharge port 27a and the second low-compression discharge port 27b have the same opening cross-sectional area, and the first low-compression discharge port 27a and the second low-compression discharge port 27b The opening cross-sectional area is formed larger than the high-compression discharge port 29.

The high-compression discharge port 29 opens in the space of the compression chamber 25 so as to discharge high-compressed air, and opens in the wall surface of the pump casing 17 in the direction of the rotation axis of the pump rotors 11a and 11b as shown in FIG. is doing.
Further, as shown in FIG. 2, the air suction port 13 is opened on the wall surface on the one end side of the pump casing 17 in the radial direction of the pump rotors 11a and 11b, and the first low compression discharge port 27a and the second low compression discharge port. The outlet 27b is opened in the wall surface on the other end side of the pump casing 17 in the radial direction of the pump rotors 11a and 11b.
As described above, the discharge ports are formed on the wall surfaces in the rotation axis direction and further in the radial direction of the pump rotors 11a and 11b of the claw type vacuum pump 9, so that the high compression discharge port 29 and the low compression discharge port 27 are provided. The booster pump 5 can be configured.

  The first low-pressure exhaust passage 30 that communicates the first low-compression discharge port 27a and the back pump 3 is provided with a first on-off valve 34 that is controlled to be opened and closed by a controller 32, and upstream of the first on-off valve 34. A second low-pressure exhaust passage 36 that joins air from the second low-compression discharge port 27b is connected. A high-pressure exhaust passage 38 is connected to the downstream side of the first on-off valve 34 in order to join air from the high-compression discharge port 29, and the high-pressure exhaust passage 38 is controlled to be opened and closed by a controller 32. A valve 39 is provided.

Next, control by the controller 32 will be described.
The pressure of the vacuum tank 7 or the inlet pressure of the booster pump 5 is input to the controller 32 from the pressure sensor 40, and an elapsed time signal is input from the timer 42.
At the beginning of exhaust, the first on-off valve 34 is closed, the second on-off valve 39 is opened, the back pump 3 is stopped, and only the booster pump 5 is driven. As a result, the exhaust from the first low-compression discharge port 27a and the second low-compression discharge port 27b is blocked, and the exhaust air from the high-compression discharge port 29 is directly discharged to the atmosphere through the high-pressure exhaust passage 38. The

In the operation stage where the air is discharged to the atmosphere through the high-pressure exhaust passage 38, the air in the tank in the atmospheric pressure state is compressed by the high compression ratio and directly discharged to the atmosphere. At this time, since the exhaust is directly performed without passing through the back pump 3, the exhaust can be performed without being affected by the back pump 3. For example, in order to increase the exhaust speed of the back pump 3, it can be discharged without using a large pump.
In addition, since the pumping speed of the booster pump 5 is larger than that of the back pump 3, the pumping speed of the booster pump 5 is reduced by the pumping speed of the booster pump 5 to reduce the pumping speed from the initial state in the atmospheric state. You can exhaust without letting.

  At the stage of operation directly discharged to the atmosphere only from the high pressure exhaust passage 38 as described above, the exhaust is performed from the atmospheric pressure state P0 at the exhaust speed Q higher than the exhaust speed of the back pump 3, as shown in FIG. The pressure is reduced to the state P1.

Next, the controller 32 determines when the preset pressure P1 in the medium vacuum state is reached by an input signal from the pressure sensor 40, opens the first on-off valve 34, and opens the second on-off valve 39. The closed back pump 3 is activated.
As a result, the exhaust from the first low-compression discharge port 27 a and the second low-compression discharge port 27 b is sent to the back pump 3.
The air in the medium vacuum state P1 is supplied to the back pump 3 from the first low-compression discharge port 27a and the second low-compression discharge port 27b, whereby the booster function of the booster pump 5 works and the exhaust speed is increased by the pressurizing action. Without being lowered, it is possible to reach the high vacuum state from the medium vacuum state P1 by the compression action of the back pump 3.

  4A is a booster pump 5, FIG. 4B is a back pump 3, FIG. 4C is a first on-off valve 34, and FIG. 4D is a time chart of the on / off timing of the second on-off valve 39. At the start of exhaustion t0, the booster pump 5 is ON, the back pump 3 is OFF, the first on-off valve 34 is closed, the second on-off valve 39 is open, and the discharge from the high compression discharge port 29 is performed. It shows that the air is discharged directly to the atmosphere through the high pressure exhaust passage 38. After that, it reaches a medium vacuum state P1 that can be reached by discharge from the high compression discharge port 29 of the booster pump 5, and when the P1 is reached, at t1, the booster pump 5 is ON and the back pump 3 is ON. Then, the first on-off valve 34 is opened, the second on-off valve 39 is closed, and the exhaust from the first low-compression discharge port 27a and the second low-compression discharge port 27b of the booster pump 5 is sent to the back pump 3. .

  As described above, according to the present embodiment, the back pump 3 can be a small pump with a small displacement by using the functions of the low compression discharge ports 27a and 27b and the high compression discharge port 29 of the booster pump 5 properly. The exhaust speed from a low vacuum state close to atmospheric pressure can be improved, and a high vacuum state can be reached without further decreasing the exhaust speed. The exhaust speed is improved in all pressure regions from atmospheric pressure to high vacuum.

Next, a second embodiment will be described.
In the second embodiment, the timing at which the controller 32 switches the booster pump 5, the back pump 3, the first on-off valve 34, and the second on-off valve 39 is replaced with an input signal from the pressure sensor 40, and the elapsed time from the timer 42. It is done by time.

  Based on the volume of the vacuum tank 7, the exhaust capacity of the compression chamber 25 of the booster pump 5, the driving conditions of the booster pump 5, the atmospheric temperature, and the like, the pressure from the atmospheric pressure P 0 is discharged in advance from the high compression outlet 29 of the booster pump 5. A time t1 until reaching P1 (intermediate vacuum state) is calculated and set.

  When the timer 42 detects that the time has reached t0 from t0, the booster pump 5 is ON, the back pump 3 is ON, the first on-off valve 34 is open, and the second on-off valve 39 is closed. By controlling to be in the state, it is possible to reach from the medium vacuum state P1 to the high vacuum state without lowering the exhaust speed.

According to the second embodiment, as in the first embodiment, the exhaust speed is improved even in the atmospheric pressure to low vacuum region, and the exhaust speed is improved in all pressure regions from the atmospheric pressure to the high vacuum state. Is made.
Further, when the pressure sensor 40 is used, the pressure sensor 40 may be clogged with dust, dust, or moisture in the vacuum tank 7 or the air passage, or may be deteriorated so that an accurate value cannot be detected. The timer 42 does not cause a problem due to such a detection error or deterioration of the sensor, so that highly reliable control can be performed.

In the first and second embodiments described above, it has been described that the controller 32 automatically controls the opening and closing of the first on-off valve 34 and the second on-off valve 39. However, the operator detects the pressure sensor 40. It goes without saying that the first on-off valve 34 and the second on-off valve may be directly opened and closed by judging from the values.
Further, the booster pump 5 has been described using the claw-type vacuum pump 9, but a low compression discharge port 27 that discharges air with a low compression ratio and a high compression discharge port 29 that discharges air with a high compression ratio are provided. Of course, if it can be provided, it is a Roots type vacuum pump and may be a screw pump.
Moreover, although demonstrated to air, other gas may be sufficient.

  According to the present invention, it is possible to provide an evacuation apparatus that improves the evacuation speed even in the low pressure region from the atmospheric pressure and improves the evacuation speed in all pressure regions from the atmospheric pressure to the high vacuum state. It is beneficial to be applied to a vacuum exhaust system in which a booster pump and a back pump are provided in series on the downstream side of the atmosphere so that a tank, a room, and the like are in a vacuum state.

It is a whole lineblock diagram showing a 1st embodiment of the present invention. It is AA sectional drawing of FIG. It is a characteristic view which shows the change of exhaust speed. (A) is a booster pump, (b) is a back pump, (d) is a 1st on-off valve, (e) is a time chart which shows each operation | movement of a 2nd on-off valve. It is a conceptual diagram of a roots type vacuum pump. It is explanatory drawing of a prior art. It is explanatory drawing of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vacuum exhaust apparatus 3 Back pump 5 Booster pump 11a, 11b Pump rotor 17 Pump casing (housing)
25 Compression chamber 27a First low-compression discharge port 27b Second low-compression discharge port 29 High-compression discharge port 32 Controller 34 First on-off valve 39 Second on-off valve 40 Pressure sensor 42 Timer

Claims (3)

In an evacuation device that is equipped with a booster pump and a back pump on the downstream side of the air in series to vacuum the tank, the room, etc.
The booster pump has a low compression discharge port that discharges at a low compression ratio in the process of being compressed in the pump chamber, and a high compression discharge port that discharges after reaching a high compression ratio. To discharge the gas from the low compression discharge port when a medium vacuum state is reached, which can be reached by discharge from the high compression discharge port. An evacuation apparatus comprising a controller for supplying gas to the back pump and operating the back pump.   2. The evacuation apparatus according to claim 1, wherein the controller detects the arrival of the medium vacuum state by elapse of time by a timer.   The booster pump is a claw-type vacuum pump, and the high compression discharge port is formed on a housing wall surface in the rotation axis direction of the rotor, and the low compression discharge port is formed on a housing wall surface in the radial direction of the rotor. The evacuation apparatus according to claim 1, wherein

Images