JP5496498B2 - Vacuum pump and method of operating vacuum pump - Google Patents

Description

  The present invention relates to a vacuum pump according to the superordinate concept of claim 1. Furthermore, the present invention relates to a method for operating a vacuum pump according to the superordinate concept of claim 8.

  Vacuum pumps in the low and medium vacuum range have fundamentally problems in compressing the gas / vapor mixture towards atmospheric pressure. If appropriate measures are not taken, vapor components may condense inside the pump stage of the vacuum pump. The vapor component is most often water vapor. Depending on the form, the vacuum pump can simultaneously compress water vapor without causing undesirable problems. This is often referred to as “water vapor tolerance”. This problem was first solved by Gaede by introducing a so-called gas ballast into the pump stage. This method is disclosed in German Patent 702480. This solution has been implemented in the prior art and has been used in various cases for quite some time.

  The disadvantage of this solution is that the final pressure of the vacuum pump is worsened by the injection of a large amount of gas ballast. In multistage vacuum pumps, the amount of gas ballast is also limited by the fact that changes are often made between the stages. On the other hand, in many applications it is observed that the vacuum pump must compress a gas / vapor mixture having a high vapor component.

  It is an object of the present invention to provide a vacuum pump capable of compressing a gas / vapor mixture having a greater amount of vapor components towards the atmosphere.

  This problem is solved by the vacuum pump having the features of claim 1 and the operating method of the vacuum pump having the features of claim 8. Dependent claims 2-7 and 9-11 provide advantageous modifications.

  Providing operating electronics for setting the cooling amount of the cooling device makes it possible to reduce the cooling amount as intended. When the cooling amount is lowered, the temperature of the vacuum pump rises based on the heat generated from the compression heat and the power loss of the driving device. This reduces the risk of vapor condensation and allows the vacuum pump to compress a gas / vapor mixture having a higher vapor content towards the atmosphere. The above disadvantages, in particular the deterioration of the final pressure, can be avoided sufficiently. A temperature sensor coupled to the operating electronics allows the temperature of the vacuum pump to be maintained at a high but not disadvantageous value. Temperatures that are too high will accelerate component degradation. In vacuum pumps lubricated with a lubricant, the lubricant is exposed to a decomposition process, particularly at high temperatures. The temperature sensor can control the temperature of the vacuum pump within a range in which such deterioration and decomposition do not occur due to a change in the cooling amount. This is limited only by the maximum cooling capacity. In order to achieve this advantage, the method steps require measuring the temperature, subsequently determining the amount of cooling required and setting the determined cooling.

  Advantageously, the vacuum pump can be improved by the selection means being coupled to the operating electronics, which allows the selection of the various operating modes of the operating electronics. This makes it possible to adapt the supply capacity for high steam components to the requirements. When a small amount of steam component is supplied, an operation method having a low operation temperature is selected. As the steam component increases, an operation method having a higher operation temperature can be selected.

Another variant further proposes providing a gas ballast supply passage which can be shut off by a valve. Thereby, the vapor component which can be supplied can further rise.
A vacuum pump comprising a ballast supply passage and selection means which can be shut off by a valve is advantageously improved by the fact that the switching state of the selection means and the switching state of the valve are coupled to each other. Thereby, when the gas ballast amount is also supplied, an operation method having a higher temperature is selected. This can be set by the aperture. In this way, the operation of the vacuum pump is simplified and an optimum tolerance for high vapor components is formed.

  One variant proposes that the valve comprises a solenoid valve in the gas ballast supply passage, the solenoid valve being coupled with the operating electronics. In this way, the operating electronics can supply additional gas ballast as needed. This makes it possible to supply also high vapor components when it is necessary to reduce the temperature.

  In an advantageous and simple variant, the cooling device comprises a fan whose rotational speed is variable. In particular, since the rotational speed of the fan can be reduced from the standard value, the supplied cooling amount can be reduced by reducing the rotational speed. This is a simple and cost-effective construction.

  In another variation, the vacuum pump comprises a lubricant sealed rotary airfoil oil rotary vacuum pump. In this case, the lubricant is responsible for many functions, such as suction chamber sealing, vane lubrication and bearing lubrication, so it is important that the steam does not condense and that the steam does not enter the lubricant circulation circuit. . Furthermore, it is important that the lubricant is not degraded by excessive temperatures.

  The method as claimed in claim 8 can be improved in another step by checking the selection means for its switching state and then determining the temperature to be achieved. This makes it possible to provide the user of the vacuum pump with a plurality of operating schemes that differ in tolerance to the vapor component in a very simple and cost-effective manner.

  Another modification suggests that the cooling is set by changing the rotational speed of the fan. This is particularly simple structurally. Furthermore, very fine changes in cooling can be made very rapidly.

  Another modification proposes that the vacuum pump has a valve in the gas ballast supply passage, and when the valve is open, the temperature of the vacuum pump is raised by reducing the rotational speed of the fan. Due to the temperature rise and the simultaneous supply of gas ballast, the highest supply capacity for the vapor component is achieved.

  Two embodiments shall explain the invention in detail and explain its advantages.

  As an initial drawing, FIG. 1 shows the structure of a two-stage vacuum pump 1 of the first embodiment. A final pump stage 2 and a medium vacuum stage 4 are arranged inside the vacuum pump. The inlet of the medium vacuum stage is connected to the container 3. The gas is drawn from the container by the medium vacuum stage and compressed by the final pump stage, so that the gas can be discharged from the vacuum pump to the atmosphere. Both pump stages are driven by one motor 5. The driving force is distributed by the transmission 6 to both pump stages. As an alternative, both pump stages may be arranged on one common shaft driven by a motor. The pump stage may be designed to compress dry, for example, by the principle of a piston. In an advantageous form, at least the final pump stage may be a lubricant-sealed rotary airfoil rotary pump.

  The vacuum pump has a fan 7, and the fan has a driving device independent of the motor 5. The driving electronic device 8 sets the rotation speed of the fan. The fan generates an air flow, thereby generating the amount of cooling utilized for cooling the pump stage and the motor. The air flow is indicated by broken line arrows in FIG. The selection means 12 is arranged on the vacuum pump so that it can be accessed by the user. This selection means makes it possible to select various operation methods. The selection means may be designed, for example, as a multipoint switch, where each position provides a respective operating mode. As an alternative, the selection means may be designed as a plug for remote operation. The mode of operation differs in the temperature range in which the vacuum pump is adjusted.

  A temperature sensor 13 located inside the vacuum pump is coupled to the operating electronics. In this example, the temperature sensor is located in the final pump stage. The temperature sensor may be located at a cooler location where the risk of condensation is particularly high, such as a pump outlet, or at a location where there is a high risk of overtemperature, such as a motor. As an alternative aspect, a plurality of temperature sensors may be provided.

  The operating electronic device is coupled to a solenoid valve 9 disposed in the gas ballast supply passage 11. This gas ballast supply passage makes it possible to supply atmospheric pressure gas into the final pump stage 2. Similarly, a throttle 10 that may be coupled to the operating electronics allows control of the amount of gas supplied via the gas ballast supply passage.

  The embodiment shown in FIG. 2 is a lubricant-sealed rotary airfoil oil rotary vacuum pump 1, which will be referred to below as a rotary airfoil oil rotary pump. The rotary airfoil rotary pump draws gas from the gas inlet 225 and discharges the compressed gas from the gas outlet 226 toward the atmosphere. Gas is compressed in the suction chamber 214 of the pump stage. The pump stage is formed by the shaft 215 passing eccentrically through the cylindrical bore, in which case the shaft supports one or more vanes 216. The shaft is rotatably supported in the slide bearing 217. The rotation of the shaft causes the vane plate to rotate in the inner hole. In this case, a crescent-shaped suction chamber is formed between the cylindrical wall and the vane plate. In this example, rotation is performed by a permanent magnet 224 and an electric coil 223 on the shaft. A separation element 218 is disposed between the electrical coil and the shaft, and the separation element is formed from a non-magnetic material. The nonmagnetic material may include glass, for example. The operation of the electric coil is performed by the driving electronic device 208. The driving electronics are configured to operate the fan 207 in addition to the drive coil. The driving electronics are in particular configured to generate various rotational speeds of the fan. The fan generates an air flow, which is indicated by the dashed arrows in FIG. The air flow is directed to the heat conducting components of the rotary airfoil oil rotary pump, particularly to the extent that includes the drive and pump stage. The heat generated within this range is received by the air flowing through the surroundings, thereby providing this range of cooling. In particular, heat is dissipated by the lubricant surrounding the pump stage housing and heated by the pump stage. The degree of cooling is a function of the strength of the air flow and the rotational speed of the fan.

  The temperature sensor 213 is located near the drive in the rotary airfoil rotary pump and outputs a signal that is a function of temperature. The temperature sensor is coupled to the driving electronics 208. The operating electronics are configured to utilize a signal that is a function of temperature to determine the required cooling. The determined cooling is then set by the operating electronics by changing the rotational speed of the fan. If an increase in temperature is required, the cooling must be reduced and thus the rotational speed is reduced. If the temperature is to be lowered, the rotational speed is increased to increase the amount of cooling as well. Since the temperature sensor is arranged in the vicinity of the driving device, and hence in the vicinity of the electronic component that is sensitive to high temperatures, the signal of the temperature sensor can be used to avoid overheating of the electronic component. The switch 212 makes it possible to set various operation methods. Since the mode of operation differs in the temperature range to which the vacuum pump is adjusted, the mode of operation is also different in water vapor tolerance. Thus, the switch may be labeled with a value or range of values for water vapor tolerance. Instead of a switch, the driving electronics may have an electronic interface through which software parameters inside the driving electronics are changed. The means for changing the software parameters may include manual devices, computers, etc., and may be separably coupled to the operating electronics.

  The gas ballast supply passage 211 connects the suction chamber 214 of the rotary airfoil oil rotary pump with the atmosphere. In this case, the inlet to the suction chamber is arranged so that the vane separates the rotary airfoil rotary pump from the gas inlet at any time. In this example, the atmosphere side inlet of the gas ballast supply passage is formed as an opening 221, and the opening can be completely or partially closed by the sleeve 220. Both the sleeve and the opening form a gas ballast valve 209.

  The rotary airfoil oil rotary pump has a cooling body 222 that acts to cool passively. The cooling body is disposed on the surface of the housing and releases heat generated in the housing to the atmosphere.

Although the rotary airfoil rotary pump of this example is shown as a single stage, there may be a plurality of pump stages arranged in series or in parallel.
Both vacuum pumps shown in the examples are operated in the manner described below by FIG. FIG. 3 shows the switching state S of the selection means 12 or switch 212 with respect to time t in the first column. The cooling amount C is scaled with respect to time t in the second row, and the cooling amount is preset by a fan having a variable rotational speed, for example. Finally, the third column shows a diagram of the temperature T with respect to time t.

Switching state S ₀ is set at time t ₁ earlier. Temperature of the vacuum pump is increased to the normal value T _N from the low temperature value T _C such as room temperature. The normal value is determined according to typical values in the prior art and is a function of operating conditions such as ambient temperature and the amount of gas to be supplied. Since the compression heat and drive loss heat the vacuum pump, a cooling amount C _N is necessary to maintain the temperature T _N.

At time t ₁ the switching state is changed to the state S _1, thereby, the operation state is selected to have a higher water vapor tolerance. From this point onward, the operating electronic device uses the signal of the temperature sensor to set the cooling amount C of the cooling means. Periods beginning this time, i.e., within a period between t ₁ and t ₅ the switching state S ₁ is given, the operation electronics is present in the control operation. It is sufficient when the driving electronics in the switching state S ₀ is a control operation.

In order to increase the water vapor tolerance, the temperature of the vacuum pump must be raised from the normal value T _N to a range between the lower limit temperature T _B and the maximum temperature T _T. To achieve this, the temperature is first measured. If the actual temperature of the vacuum pump is present below the temperature T _B, the cooling amount is reduced to a low value C _1. Due to the reduced cooling, the vacuum pump is heated by the heat of compression and power loss. At time t _2, the vacuum pump has reached the lower limit temperature T _B. At this time, in order to moderate heating, cooling amount is set high to an intermediate value C _2. When the maximum temperature T _T is reached, the cooling rate is raised to a higher value C ₃ in order to cool the vacuum pump and avoid overheating. Temperature is lowered due to strong cooling, thereby, again has reached the lower limit temperature T _B in the final time point t _4. Upon reaching this temperature, the cooling amount is reduced to C ₂ again, thereby, the vacuum pump is heated again.

At time _{t 5,} the switching state is to have been changed from _{S 1} to _{S 0.} At this time, since the normal cooling amount C _N is set, the temperature of the vacuum pump is lowered to the normal value T _N.
FIG. 4 shows two simple possibilities for setting the amount of cooling. For this purpose, the cooling amount C is given in the upper diagram, the rotation speed f of the fan in the first operation method is given in the second diagram, and finally the second operation method is shown in the lower diagram. The rotational speed f ′ of the fan at is given.

Before the time point t ′ ₁ , the vacuum pump is in the first operation state, and in this operation state, the cooling amount is determined according to the heat input amount due to compression and driving loss. The maximum cooling amount C ′ _N prevents the vacuum pump from overheating to unfavorable values, even under unfavorable operating conditions, for example very high ambient temperatures of 40 ° C. It is assumed that at time t ′ ₁ , an operating state having a higher water vapor tolerance is selected by the selection means, and this operating state is terminated again at time t ′ ₃ .

In a first example of a cooling amount setting, the fan speed from the rotational speed f _N which is adapted to cool the amount C _'N, is reduced to a lower rotational speed f _1. Thereby, the cooling amount is reduced. Assume that a higher amount of cooling was required after time t ′ ₂ and therefore the rotational speed is set to a value f ₂ between f _N and f ₁ . In t _'3 and later, the fan shall be again rotated at the first rotational speed f _N. The rotational speed control may be performed continuously instead of using the discrete rotational speed value.

In the second example of the cooling amount setting, the cooling amount is set by the pulsating operation of the fan. Between times t ′ ₁ and t ′ ₂ , the fan is operated at a lower rotational speed, including the fan stop, and is switched to another rotational speed only for pulse 41. Another rotational speed may be the rotational speed f ′ _N in a simple example. This pulsating operation results in a lower amount of cooling averaged over the period t ′ ₁ -t ′ ₂ . Suppose that a higher amount of cooling is required within the period t ′ ₂ -t ′ ₃ . This is obtained by using more pulses 42. The cooling amount can be set to a necessary value by changing the pulse height, the pulse width, and the number of pulses.

1 is a general structural diagram of a first vacuum pump according to the present invention. 1 is a cross-sectional view of an oil-sealed rotary airfoil oil rotary vacuum pump according to the present invention. It is a time diagram of temperature, a switching state, and cooling. It is a time line figure of cooling and rotation speed of a fan.

Explanation of symbols

1: 201 Vacuum pump 2: 214 Final pump stage (including suction chamber)
3 Container 4 Medium vacuum stage 5 Motor 6 Transmission device 7; 207 Cooling device (fan)
8; 208 Operating electronics 9, 209 Valve 10 Throttle 11; 211 Gas ballast supply passage 12; 212 Selection means (including switch)
13; 213 Temperature sensor 41, 42 Pulse 215 Shaft 216 Blade plate 217 Slide bearing 218 Separating element 220 Sleeve 221 Opening 222 Cooling body 223 Electric coil 224 Permanent magnet 225 Gas inlet 226 Gas outlet C, C ₁ , C ₂ , C ₃ , C _N cooling amount f, f 'rotation speed S of the _fan, S 0, _{S 1} switching state _{T, T B, T C,} T N, T T temperature t time t ₁ -t ₅ time t _W period

Claims (7)

In a vacuum pump (1; 201) comprising a pump stage (2; 214) and a cooling device (7; 207) for compressing and discharging a mixture of gas and vapor to the atmosphere,
A vacuum pump (1; 201) is coupled to the operating electronics (8; 208) for setting the cooling amount of the cooling device (7; 207) and to the operating electronics (8; 208). and having a; (213 13), a temperature sensor
A selection means (12; 212) is coupled with the driving electronics (8; 208), the selection means enabling selection of various driving modes of the driving electronics;
The cooling device (7; 207) includes a fan, and the rotational speed of the fan compresses a mixture of gas and vapor having a higher vapor content and reduces the risk of condensation of the vapor, toward the atmosphere. In order to control the amount of cooling so that it can be discharged, it is possible to reduce from the standard value that generates the amount of cooling required to achieve the temperature determined by the switching state of the selection means (12; 212). And
A vacuum pump characterized by The pump stage (2; 214), the valve vacuum pump according to claim 1, characterized in that it comprises a; (211 11) blockable gas ballast supply passage (9 209). 3. The vacuum pump according to claim 2 , wherein the switching state of the selection means (12; 212) and the switching state of the valve (9; 209) are combined. 4. The vacuum pump according to claim 2, wherein the valve (9; 209) comprises a solenoid valve, the solenoid valve being coupled with the operating electronics. Any vacuum pump of claims 1 to 4 vacuum pump and having an oil seal rotating airfoil oil rotary pump stages (214). In a method of operating a vacuum pump (1; 201) having a pump stage (2; 214) and a fan (7; 207) that compresses and discharges a mixture of gas and steam to the atmosphere,
That the temperature is measured,
Followed by the required amount of cooling ,
Next, the determined cooling amount is set,
The selection means (12; 212) enabling the selection of the various operating modes of the operating electronics (8; 208) for setting the cooling amount of the fan (7; 207) is checked for its switching state and thereafter The temperature to be achieved and its temperature so that a mixture of gas and steam having a higher vapor content can be compressed and discharged towards the atmosphere while reducing the risk of vapor condensation The required amount of cooling is determined according to
The cooling is set by changing the rotational speed of the fan (7; 207);
A method of operating a vacuum pump (1; 201) characterized by When the vacuum pump (1; 201) has a valve (9; 209) in the gas ballast supply passage (11; 211) and the valve is open, the temperature of the vacuum pump (1; 201) is the fan The operating method of the vacuum pump (1; 201) according to claim 6 , wherein the operating speed is increased by a decrease in the rotational speed (7; 207).

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