JP2015014285A - Diaphragm vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm vacuum pump capable of overcoming defects of a conventional technology, and completely and surely preventing, in particular, formation of condensate at any time, so that pump characteristic of the vacuum pump is not deteriorated.SOLUTION: A diaphragm vacuum pump includes at least one diaphragm pump stage, at least one inlet valve disposed on the diaphragm pump stage for a process gas to be transferred, and at least one gas ballast valve for supplying a ballast gas. A flow channel for the ballast gas passing through the gas ballast valve is connected to a flow channel for the process gas at the back of the inlet valve in the flowing direction of the process gas.

Description

  The present invention relates to a diaphragm vacuum pump having at least one diaphragm pump stage.

  Diaphragm vacuum pump is suitable for evacuating gas volume, depending on the application, either directly connected to the volume to be evacuated or another vacuum pump connected in front of the diaphragm vacuum pump in the flow direction For example, it can be used as a preliminary vacuum pump for a turbo molecular pump. In order to provide the desired output characteristics, the diaphragm vacuum pump can have one or more diaphragm pump stages, which can be connected one after the other in the flow direction or in parallel with each other. Because of this, these diaphragm pump stages pump in series or in parallel with each other.

  The problem with the known diaphragm vacuum pump is the condensation of water vapor in the pump chamber (suction chamber) of the vacuum pump, which is because the condensate present in the pump chamber impairs the functional reliability of the vacuum pump. This is because the lifetime is shortened.

  In order to reduce the effect of fluid condensation on the functional reliability and life of the diaphragm vacuum pump, a ballast gas device can be used to introduce ballast gas (gas ballast) into the pump chamber of the vacuum pump. In this case, the ballast gas is used to prevent the formation of condensate and to remove the existing condensate from the pump chamber. However, with known ballast gas devices, condensate formation is not always reliably prevented anywhere in the pump chamber, and the amount of ballast gas that can be supplied is limited. Furthermore, the final vacuum pressure to be achieved by a vacuum pump when using known ballast gas devices is increased.

  In addition, the known ballast gas devices significantly increase the structural space required for the realization of the vacuum pump and do not allow temporal automatic control of the ballast gas supply.

German Patent No. 43 20 963 German Patent Application Publication No. 198 51 680 German utility model No. 29 618 911

  Accordingly, the object of the present invention is to provide a diaphragm vacuum pump which overcomes the above-mentioned drawbacks, and in particular prevents condensate formation completely and reliably at any time, and thereby does not deteriorate the pump characteristics of the vacuum pump. is there.

  This problem is solved by a diaphragm vacuum pump having the features of claim 1.

  The diaphragm vacuum pump comprises at least one diaphragm pump stage, at least one inlet valve for the process gas to be transferred attached to the diaphragm pump stage, and at least one gas ballast valve for supplying ballast gas. Have A flow path for the ballast gas through the gas ballast valve is connected to the flow path for the process gas after the inlet valve in the flow direction of the process gas.

  Since the ballast gas path is connected to the process gas path after the inlet valve in the process gas flow direction, the inlet valve causes the ballast gas to flow to the pump inlet of the diaphragm vacuum pump in the opposite direction to the process gas flow. This prevents increasing the achievable final vacuum pressure of the pump. At the same time, the ballast gas can reach the entire pump chamber of the diaphragm vacuum pump, so that a complete cleaning of the pump chamber can be obtained and condensate formation can be effectively prevented everywhere. Pump characteristics, in particular the achievable final pressure degradation, are also avoided when supplying large amounts of ballast gas, which reliably and completely prevents condensate formation.

  Advantageous embodiments of the invention are described in the dependent claims, the description and the figures.

  According to an advantageous embodiment, the flow path for the ballast gas is connected to the flow path for the process gas immediately after the inlet valve. This ensures that the entire pump chamber of the vacuum pump is cleaned by the supplied ballast gas and that condensate formation is effectively avoided everywhere in the pump chamber.

  The flow path for the ballast gas can be connected to the flow path for the process gas, for example in a connection area or connection passage located between the inlet valve and the suction chamber of the diaphragm pump stage, so that this area is also ballasted. It can be cleaned with gas. The suction chamber of the diaphragm pump stage can be defined by a stationary head cover and a movable diaphragm in a manner known per se. In this case, the connection region or connection passage between the inlet valve and the suction chamber can be completely or partly defined by the head cover.

  Also, the flow path for the ballast gas is connected to the suction chamber in the immediate vicinity of the connection passage for the process gas, or the flow path for the ballast gas and the flow path for the process gas are connected to the suction chamber. Crossing can be done in the area of the common opening.

  The flow path for the ballast gas can pass through a ballast gas passage, in particular at least partly, in particular completely defined by the head cover of the diaphragm pump stage.

  The valve is preferably an electrically operable valve. According to an advantageous embodiment, the gas ballast valve is a solenoid valve. Such a valve can be realized in a small structural space and can be electrically controlled, so that the valve can be automatically operated.

  For example, in order to achieve temporal control of the valve operation, it is preferable if a particularly digital control device is provided which is operatively coupled to the gas ballast valve and can be electrically controlled for operation. In particular, the gas ballast valve can be automatically controlled so that the operation of the gas ballast valve is performed with the dependence set for the pump operation of the vacuum pump, for example, in order to avoid condensate formation as completely as possible. For example, at the beginning of the pump cycle of a vacuum pump, a predetermined cleaning cycle can be automatically performed in which the pump chamber is cleaned with ballast gas. This cleaning cycle can be followed by an output cycle in which no ballast gas is supplied.

  The control device is provided by a sensor of the vacuum pump and / or an external sensor and relies on a measurement signal depending on a measurement value which depends on the operation of the vacuum pump or the process to be performed in the vacuum to be generated. Can be used to operate the device.

  Since the control unit is programmable, the desired automatic operation of the gas ballast valve can be set individually by the user, for example in the form of an adjustable cleaning cycle.

  The vacuum pump can have at least one other diaphragm pump stage in addition to one diaphragm pump stage. According to an advantageous embodiment, this further diaphragm pump stage is connected after one diaphragm pump stage in the direction of the process gas flow, so that the ballast gas is first fed by one pump stage and then the subsequent. It is transferred by another pump stage. In this configuration, the ballast gas supplied to the suction chamber of the first diaphragm pump stage automatically reaches another subsequent pump stage as a result of the pumping action of the vacuum pump, so that both pump stages are cleaned. This protects against condensate formation.

  A diaphragm pump stage as a whole can have more than two, in particular three, four or more than four diaphragm pump stages. In this case, the gas ballast valve is disposed at the beginning of the diaphragm vacuum pump as viewed in the flow direction of the process gas, that is, attached to the pump stage following the pump inlet of the diaphragm vacuum pump without interposing another pump stage. It is preferable. Another diaphragm pump stage can be connected later in the direction of the process gas flow of the pump stage attached to the gas ballast valve, so that the ballast gas supplied to the first pump stage is not in operation of the vacuum pump. In addition, the pumps are also transferred through another pump stage to wash these pump stages.

  The flow rate of the ballast gas that can be supplied to the pump via the gas ballast valve depends on the flow guide value of the gas ballast valve. Thus, in order to achieve the desired flow rate, a gas ballast valve with a corresponding flow guide value can simply be used. Additional throttling of the vacuum pump to achieve the desired flow rate can be omitted.

  According to an advantageous embodiment, the gas ballast valve has an adjustable guide value. In this case, the flow rate of the ballast gas that can be supplied to the pump can be adjusted simply by adjusting the guide value to a desired value.

  As a result of the introduction of the ballast gas in the direction of the process gas flow after the inlet valve, it can be operated with a high ballast gas amount that ensures a reliable cleaning of the entire pump chamber without degrading the output characteristics of the pump . For example, if the final pressure achievable at the pump inlet of the diaphragm vacuum pump is dominant and there is no gas load, the ballast gas flow rate that can be supplied via the gas ballast valve is 10% or more of the suction capacity of the vacuum pump, preferably Can be adjusted to 20% or more, particularly preferably 30% or more.

  In principle, it is preferred that the gas ballast valve has at least two switching positions, in which the ballast gas can be supplied to the pump chamber of the vacuum pump at one switching position of the gas ballast valve, and the gas at the other switching position. The ballast valve constitutes a gas tight closure for the pump chamber.

  The gas ballast valve is in particular a three-way two-position valve. The gas ballast valve accordingly comprises in particular two inlets and one outlet, which outlets can be connected to direct gas to one of the two inlets selectively by switching the gas ballast valve. The outlet of the gas ballast valve is connected in particular to direct the gas to the pump chamber of the pump, but one of the inlets can be supplied in particular with ballast gas and the other inlet is particularly gas tightly sealed. ing. Thus, the ballast gas can be supplied to the pump chamber at one switching position, but the gas ballast valve constitutes a gas tight closure for the pump chamber at the other switching position.

  The inlet valve of the diaphragm pump stage and / or the outlet valve of the diaphragm pump stage can be configured such that it allows the gas flow to pass only in the desired flow direction of the process gas and prevents reverse gas flow. For example, the inlet valve and / or the outlet valve of the diaphragm pump stage can be formed as a gas flow controlled valve, such as a gas flow controlled flutter valve. Thus, the supply of ballast gas after the inlet valve in the flow direction avoids backflow of ballast gas opposite to the process gas flow direction.

  According to an advantageous embodiment, a filter, in particular a fine filter, is provided for filtering the ballast gas. This filter is disposed in front of the connecting portion where the flow path of the ballast gas is connected to the flow path of the process gas, particularly in the flow direction of the ballast gas. The filter can be placed in front of the gas ballast valve in the flow direction of the ballast gas. This protects the gas ballast valve and pump chamber of the vacuum pump from external contamination.

  In another embodiment, the vacuum pump drive unit and gas ballast valve can be operated at the same value of voltage, such as 24 volts. Accordingly, a common power supply unit can be provided to provide power supply for the drive unit and the gas ballast valve. This reduces the costs required for manufacturing the vacuum pump.

  A further object of the present invention is to provide at least one diaphragm vacuum pump according to the above description and at least one other vacuum pump connected in series with the diaphragm pump to direct gas upstream of the diaphragm vacuum pump. It is a pump apparatus which has. Another vacuum pump can be, for example, a turbomolecular pump, a single or multi-stage roots pump, a rotary vane pump, a scroll pump, a claw pump, a screw pump, a rotary piston pump or an ion getter pump.

  The diaphragm vacuum pump is used as a preliminary vacuum pump, especially for another vacuum pump connected before. The gas ballast valve prevents the formation of condensate in the diaphragm vacuum pump, thus increasing the operating reliability, reliability and operating life of the diaphragm vacuum pump, thereby providing for another vacuum pump by the diaphragm vacuum pump The possible pre-vacuum pressure is not increased.

  In the following, the invention will be described by way of example on the basis of advantageous embodiments in connection with the attached figures.

1 is a cross-sectional view of a diaphragm vacuum pump according to an embodiment of the present invention.

  The diaphragm vacuum pump shown in FIG. 1 has a first diaphragm pump stage 12 and a second diaphragm pump stage 14, and these diaphragm pump stages are connected one after the other in the flow direction and perform pumping work in series. Do. The first pump stage has an inlet 18, which at the same time constitutes the pump inlet of the pump. Connected to the inlet 18 is a supply line 60 for the process gas to be transferred. The supply line 60 can connect a diaphragm vacuum pump, for example to the outlet of a previously connected turbomolecular pump, so that the diaphragm vacuum pump is used as a spare pump for the turbomolecular pump.

  From the inlet 18, an inlet passage 24 formed in the pump housing 16 leads to the inlet valve 20 of the pump stage 12. The inlet valve 20 is formed as a gas flow control valve having a valve plate 64 and allows gas flow only in the process gas flow direction indicated by arrow 56 in FIG. Inlet valve 20 specifically defines a housing cover of housing 16 that defines inlet passage 24 and a suction chamber 30 of pump stage 12 and is not shown as a separate part in FIG. It is disposed between the head covers of the housing 16.

  A connection passage 26 extending through the head cover is disposed on the outlet side of the inlet valve 20, and this connection passage connects the outlet side of the inlet valve 20 to guide the gas to the suction chamber 30 of the pump stage 12. The suction chamber 30 is defined by a head cover and a diaphragm 32, and this diaphragm is supported by a crankshaft 35 that can be driven to rotate via a connecting rod 34.

  In addition, the pump shown in FIG. 1 has a gas ballast valve 22, which is supplied with ballast gas via a supply line 62. The gas ballast valve is formed as a three-way two-position valve and has one outlet and two inlets. The outlet of the gas ballast valve 22 is connected to guide gas to a ballast gas passage 28 defined by the head cover of the pump stage 12, and this ballast gas passage is connected to a connection passage 26.

  Since one of the inlets of the gas ballast valve 22 is connected to a supply line 62 for ballast gas, the supply line 62 is connected at a corresponding switching position of the gas ballast valve 22, and the ballast gas is ballasted according to the arrow 58. It is transferred to the gas passage 28 and from there to the suction chamber 30 via the connection passage 26. Since the other inlet of the gas ballast valve 22 is gas tightly sealed, the gas ballast valve 22 constitutes a gas tight plug for the pump chamber in the corresponding switching position illustrated in FIG.

  The gas ballast valve 22 is formed as an electromagnetic valve and is connected to an electronic control unit (not shown in FIG. 1). The electronic control unit automatically controls the gas ballast valve 22. The gas ballast valve 22 is illustrated in the schematic diagram of FIG. 1 in a separate supply line 62 for ballast gas. The gas ballast valve 22 is actually fixedly coupled to the housing 16 of the diaphragm vacuum pump, in particular the housing cover or the head cover of the first pump stage 12, and can be integrated in particular in the housing 16. For example, the gas ballast valve 22 may be coupled directly to the housing 16 at the inlet of the ballast gas passage 28 and / or the gas ballast valve 22 may be fully or partially disposed within the ballast gas passage 28. can do.

  Further, the pump stage 12 has a gas flow controlled outlet valve 36, which is connected on the inlet side to direct gas to the suction chamber via a connecting passage located in the head cover, It is configured to pass the transferred gas only in the flow direction 56 away from the suction chamber. The outlet valve 36 is connected to the outlet 38 of the pump stage 12 on the outlet side.

  The connection line 40 connects the outlet 38 to the first pump stage 12 and the inlet 42 of the second pump stage 14, so that the pump stages 12, 14 are connected in series in the flow direction 56 and are connected in series with each other. Pump work. In principle, it is also possible to connect both pump stages in parallel with each other, so that both pump stages perform pumping work in parallel with each other. For this reason, it is possible to connect the inlets of both pump stages to the pump inlets of the vacuum pumps and connect the outlets of both pump stages to the pump outlets of the vacuum pumps.

  The second pump stage 14 is formed substantially the same as the first pump stage 12. The second pump stage inlet 42 is followed by a gas flow controlled inlet valve 44 having a valve plate 68, which connects the inlet 42 to the suction chamber 46 of the second pump stage 14. The suction chamber 46 is defined by a head cover and a diaphragm 48 of the housing 16 that are not shown as separate parts in FIG. 1 as previously described with respect to the first pump stage 12, which diaphragm connects the connecting rod 50. It is connected to a crankshaft 35 that can be rotationally driven. The second pump stage 14 has an outlet valve 52 having a valve plate 70 through which the gas discharged from the suction chamber 46 can be supplied to the outlet 54 of the second pump stage 14. Yes, this outlet simultaneously constitutes the pump outlet of the diaphragm vacuum pump.

  The function system of the vacuum pump shown in FIG. 1 will be described below.

  Since the crankshaft 35 is rotationally driven during the operation of the vacuum pump, the connecting rods 34 and 50 are periodically moved up and down together with the diaphragms 32 and 48 of both pump stages 12 and 14 fixed thereto. The cycle consists of a suction stage for drawing the gas to be transferred into the suction chambers 30 and 46 via the respective inlet valves 20 and 44 for each pump stage 12 and 14, and the outlet valve 36 and the gas to be transferred. There is a subsequent evacuation stage for evacuating the suction chambers 30 and 46 via 52 and thereby performing pumping operations. The connecting line 40 guarantees serial pumping, in which the gas to be transported that is stagnant at the inlet 18 is first in the direction of the arrow 56 first followed by the first pump stage 12 and the second pump stage 14. Through the outlet 54.

  At the final stage of the pump cycle, the gas ballast valves 22 are each in the switching position shown in FIG. At this position of the gas ballast valve 22, the gas ballast valve 22 constitutes a gas tight closure for the pump chamber so that the ballast gas does not reach the pump chamber.

  In order to avoid the formation of condensate in the pump chamber of the vacuum pump and to remove the condensate present, a cleaning cycle is carried out regularly, especially at the beginning of each pump cycle of the pump, during which the gas The ballast valve 22 is in the second switching position.

  In the second switching position of the gas ballast valve 22, the supply line 62 for the ballast gas can be passed, so that the pump stages 12, 14 are in addition to the gas to be transferred stagnant at the inlet 18. Ballast gas is transferred to the pump chamber of the diaphragm vacuum pump through the ballast gas passage 28. The flow path of the ballast gas is connected to the flow path of the process gas immediately after the inlet valve 20 in the region of the connection passage 26 and thus in the flow direction of the process gas. Therefore, the entire pump chamber of the pump stages 12, 14 after the inlet valve 20 is cleaned with ballast gas, so that condensate formation is effectively avoided everywhere.

12, 14 Pump stage 16 Housing 18 Inlet 20 Inlet valve 22 Gas ballast valve 24 Inlet passage 26 Connection passage 28 Ballast gas passage 30 Suction chamber 32 Diaphragm 34 Connecting rod 35 Crankshaft 36 Outlet valve 38 Outlet 40 Connection line 42 Inlet 44 Inlet valve 46 Suction chamber 48 Diaphragm 50 Connecting rod 52 Outlet valve 54 Outlet 56, 58 Arrow 60 Process gas supply line 62 Ballast gas supply line 64, 66, 68, 70 Valve plate

Claims (10)

  At least one diaphragm pump stage (12), at least one inlet valve (20) for the process gas to be transferred associated with the diaphragm pump stage (12), and at least one for supplying ballast gas A flow path for the ballast gas through the gas ballast valve (22), and a flow path for the process gas after the inlet valve (20) in the flow direction of the process gas. Connected diaphragm vacuum pump.   2. The diaphragm vacuum pump according to claim 1, wherein the flow path for the ballast gas is connected to the flow path for the process gas immediately after the inlet valve (20).   The diaphragm vacuum pump according to claim 1 or 2, wherein the gas ballast valve (22) is a solenoid valve.   4. The control device according to claim 1, further comprising a control device that is operatively coupled to the gas ballast valve and is capable of controlling the gas ballast valve for operation. 5. Diaphragm vacuum pump.   In addition to one diaphragm pump stage (12), at least one other diaphragm pump stage (14) is provided, which is another diaphragm pump stage, particularly in the direction of the process gas flow. The diaphragm vacuum pump according to any one of claims 1 to 4, characterized in that it is connected after the pump stage (12).   6. The diaphragm vacuum pump according to claim 1, wherein the gas ballast valve (22) has an adjustable guide value.   The diaphragm vacuum valve according to any one of claims 1 to 6, wherein the gas ballast valve (22) is a three-way two-position valve.   A filter is provided for filtering the ballast gas, and this filter is arranged in front of the connecting portion where the flow path of the ballast gas is connected to the flow path of the process gas, particularly in the flow direction of the ballast gas. The diaphragm vacuum pump according to any one of claims 1 to 7.   Common power to provide that the vacuum pump drive unit and gas ballast valve (22) can be operated at the same value of voltage and / or provide power for the drive unit and sub-ballast valve (22). The diaphragm vacuum pump according to any one of claims 1 to 8, wherein a supply unit is provided.   An at least one diaphragm vacuum pump according to any one of claims 1 to 9, and another vacuum pump connected in series with the diaphragm pump so as to introduce gas upstream of the diaphragm vacuum pump. A pump device in which the further vacuum pump is in particular a turbomolecular pump, a single-stage or multi-stage roots pump, a rotary vane pump, a scroll pump, a claw pump, a screw pump, a rotary piston pump or an ion getter pump.

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