JP6796630B2 - Vacuum pump - Google Patents

Description

The present invention relates to a vacuum pump having one first working pump portion and at least one second working pump portion.

The prior art will be described below based on the example of a rotary vane vacuum pump having two actuating pump parts.

The known vacuum pump of the type described above is formed so that the actuating pump portions are connected in parallel. As a result, relatively large suction performance is realized at the initial stage of the suction process. The parallel connection of the working pump parts, however, is disadvantageous with respect to the achievable final pressure, i.e. the minimum achievable pressure at the vacuum pump inlet.

In prior art, it is known to connect two actuating pump parts in series, especially in applications where low final pressures are required. This makes it possible to achieve a clearly lower final pressure in the otherwise structurally same actuating pump portion. However, the suction performance at a high inlet pressure, that is, especially at the initial stage of the suction process, is significantly reduced as compared with the parallel operation.

The type of vacuum pump that operates in parallel as described at the beginning is suitable for applications where rapid suction is prioritized over achievable low final pressure. Conversely, vacuum pumps operating in series are particularly suitable for applications where rapid suction is relatively unimportant, but exceptionally low final pressures should be achievable. Suction performance at high inlet pressures and achievable final pressures have so far been at odds with each other.

The object of the present invention is to improve the performance of the vacuum pump of the type described at the beginning, to realize high suction performance especially at high pressure even at the early stage of the suction process, and to realize low final pressure that can be achieved. is there. In other words, in particular, the above-mentioned conflicting state of purpose should be resolved.

This problem is solved by a vacuum pump having the characteristics according to claim 1. In particular, the solution is provided by the fact that a control device is provided, which allows the series connection and parallel connection of the operating pump portion to be switched.

Thereby, depending on the operating state of the vacuum pump, it is possible to wash the operating state that exerts better performance, that is, the series connection or the parallel connection. The vacuum pump can be operated in parallel connection of the working pump parts, for example in the early stages of the suction process, in order to achieve high suction performance, and later, especially in series operation, the suction performance is operated in parallel. Beyond that in, it is switched to series operation, thus ensuring more efficient evacuation up to exceptionally low final pressures.

The vacuum pump according to the invention can be flexibly used in various application cases. Further, on the manufacturing side, it is possible to omit providing a plurality of mechanically different vacuum pumps, one connected in parallel and the other connected in series. As a result, duplication of parts is significantly reduced, and thus cost reduction is possible. The structurally high cost for the controller can be kept low relative to this. In addition, the cost advantage comes from the fact that smaller pumps can be connected in parallel and used in multiple applications, such as where larger pumps were previously used.

As long as high or low pressures are mentioned here, they should never be understood with respect to specific vacuum applications. In the simple case of atmospheric pressure at both the inlet and outlet in the initial state of the pump, higher pressures are particularly relevant for values close to atmospheric pressure.

The following description, by way of example, primarily relates to a vacuum pump having exactly two actuating pump parts operating according to the same pump principle. The above-mentioned example, however, can be diverted to a pump having three or more working pump parts, or can be diverted to a pump having different types of working pump parts.

According to one embodiment, the vacuum pump is a rotary discharge vacuum pump, especially a rotary vane pump. In particular, both working pump parts, or all working pump parts, follow a rotary discharge principle or a rotary vane principle. For example, the actuating pump portion is driven by a common shaft. This is a structurally simple and therefore inexpensive solution.

According to another embodiment, the control device is formed to perform switching when a pre-given switching gas pressure and / or a pre-given switching gas pressure is achieved. This is particularly advantageous because the suction performance depends on the working pressure present at each time point, so the suction performance can be selected accurately.

The switching gas pressure can be, for example, the gas pressure present at the inlet of the vacuum pump. This makes it available that the inlet pressure of the vacuum pump is often monitored anyway, thus eliminating the need for an additional pressure detector.

The advantageous value of the switching gas pressure is below 1 hPa and / or above 0.01 hPa, preferably above 0.10 hPa.

In the advanced form, the control device is formed so that the switching is performed according to the gas pressure at the inlet of the vacuum pump according to the known suction performance transition in the series connection and the parallel connection of the vacuum pumps. .. In particular, switching between series connection and parallel connection can be performed at the intersection of suction performance transitions.

In a further development, the pumping process is initiated by the parallel connection of the actuated pump parts, and the suction performance of the vacuum pump is lower, or at least basically the same, in the parallel connection than the suction performance of the series-connected vacuum pump. If so, a control device is formed so as to switch to the series connection of the operating pump portion. Thereby, it is possible to adjust each advantageous suction performance.

In another embodiment, the control device has at least one switching valve, especially a magnet valve. Such a switching valve allows for easy and reliable control, or switching. For example, a three-way valve, particularly one with an operating voltage of 24 V, may be intended.

The switching valve has, for example, at least two switching states, one of which is assigned a series connection and the other a parallel connection.

In another embodiment, the switching valve has at least one third switching state, in which the actuating pump portion is separated from the inlet of the vacuum pump. This makes it possible to ensure that the outlet and actuation pump portion of the vacuum pump are separated from the inlet. Therefore, in particular, the function of the inlet valve or the safety valve can be carried by the switching valve. The vacuum pump, in particular, does not have an additional inlet valve, or safety valve. Not only is this possible to reduce costs, but it also avoids the disadvantages that often occur with inlet valves, that is, in the differential pressure of the inlet valve, a low differential pressure often leads to inadequate closure of the inlet. Is possible. The switching valve, on the contrary, efficiently closes the inlet at any differential pressure.

High operational safety is formed so that, for example, the switching valve automatically takes and holds the third switching state when there is no flow in the third switching state, or in the absence of current. Has been done. This avoids the backflow of process gas into the vessel in the event of a current failure, and in particular the reverse rotation of the pump shaft caused by it.

The switching valve can be formed, for example, as a 5/3 directional valve. This allows for a structurally simple aspect.

In another embodiment, the drive unit for at least one, in particular both, or all actuating pump parts has one DC motor. This DC motor is electrically connected in series with the switching valve. Thus, the motor in a simple way, is capable of being controlled switching valve and the synchro (sync) to. In particular, here, the state where there is no current for switching the switching valve can lead to a safe state or a third switching state.

In another embodiment, the controller has at least one separate valve, which separates the first actuating pump portion from the outlet of the vacuum pump for the realization of a series connection.

The problem of the present invention is also solved by the method of claim 15, particularly by switching between series and parallel connections of the actuating pump portion during the pumping process.

The method according to the invention can be developed, for example, in the sense of an embodiment of the vacuum pump described herein, and conversely, the vacuum pump according to the invention can be developed in the sense of an embodiment of the method described herein. Is.

Another embodiment of the invention can be found in the dependent claims, the specification, and the drawings.

The present invention will be described below, merely exemplary, with reference to simplified drawings.

Side view of rotary discharge type vacuum pump in the prior art Sectional view of the vacuum pump of FIG. 1 along line AA of FIG. The figure which described the suction performance according to the inlet pressure for the series connection and the parallel connection of the operation pump part for the vacuum pump according to the invention, respectively. Schematic of a 5/3 directional valve for switching between series and parallel operation of two actuating pump parts

FIG. 1 shows a rotary discharge type vacuum pump according to a prior art, which is formed as a rotary vane vacuum pump and is hereinafter referred to as a vacuum pump 10. The vacuum pump 10 sucks the working medium at the inlet 28 and conveys it to the outlet 30. Outlets are open to the atmosphere, for example.

FIG. 2 shows a cross-sectional view of the vacuum pump 10 along the line AA of FIG. At that time, the cross section extends in parallel along the rotation axis of the rotor 12 of the vacuum pump 10. The vacuum pump 10 has a safety valve 20. This prevents backflow of the working medium in the event of a pump failure. The safety valve 20 is pre-controlled by pressure pre-control.

The vacuum pump 10 further has a motor 26 for operating the rotor 12 of the vacuum pump 10. A coupling 27 is provided between the motor 26 and the rotor 12. It can be specifically formed as a magnetic coupling.

The rotor 12 is formed with two operating pump portions and one control pump portion. The first actuating pump portion is defined by a slider 14 and a transport space 15. The second actuating pump portion is defined by the slider 16 and the transport space 17. Within the control pump portion the rotor has a slider 18. This rotates the transport space 19 and transports the control fluid for pressure pre-control. The indicated vacuum pump 10 operates according to the principle of the rotary vane pump, that is, in the first working pump part, in the second working pump part, and in the control pump part. A plurality of sliders 14 or 18 may be provided in each pump portion.

The rotor 12 has control portions 18 and 19 housed and supported within the housing portion 24 and rotatably supported therein. The accommodating portion 24 forms a basic cylindrical shape on the outer surface 32. This basic shape is formed in a conical shape with respect to the rotation axis of the rotor 12.

In the graph shown in FIG. 3, the abscissa indicates the inlet pressure of the vacuum pump according to the present invention on a logarithmic scale. The ordinates indicate the suction performance of the pump in a simple memory. The graph shows two suction performance transitions according to the inlet pressure. That is, the first suction performance transition SP and the second suction performance transition SR. The first suction performance transition represents the suction performance transition when the operating pump portions are connected in parallel, and the second suction performance transition represents the suction performance transition when the operating pump portions are connected in series.

FIG. 3 impressively shows that the suction performance is clearly higher in parallel operation than in series operation at high inlet pressures, especially early in the suction process starting from atmospheric pressure. But in parallel operation, only clearly higher final pressures are achieved.

In the example shown here, the suction performance transitions intersect when the inlet pressure is about 0.15 hPA. The intersections and transitions themselves, however, depend on the structural morphology of each actuating pump portion and their mutual size ratio. At that time, it is a fact that the smaller the size difference of the operating pump portion, the greater the improvement in suction performance.

The intersection can advantageously be used as a switching point between parallel and series operation of the vacuum pump controller. In particular, the switching gas pressure corresponding to the intersection is detected and is the basis for control.

The graph of FIG. 3 is read from right to left to illustrate the suction process. The advantageous suction process begins in parallel operation, especially starting from atmospheric pressure, where high suction performance according to SP is used for rapid evacuation. However, when the suction performance falls below what is possible in series operation in parallel operation, it is switched to series operation, resulting in the use of higher suction performance equivalent to SR in the lower pressure range, and more. It is possible to achieve a low final pressure.

FIG. 4 shows the switching valve 40. It is formed as a 5/3 directional valve and controls the vacuum pump according to the invention. The switching valve 40 has switching points (a), (b) and (c). Of these, the two actuating pump parts 42 and 44 are connected in different ways. The switching valve 40 is formed as a magnet valve for the purpose of selecting a desired switching state, in which the corresponding magnet device is not represented in detail.

In addition, a sequence of fluid channels is represented. These connect the inlet 28 of the vacuum pump to the outlet 30 of the vacuum pump via the switching valve 40 and the actuating pump portions 42, 44. Further, a switching valve 46 is provided. It can be selectively blocked.

In the switching state (a), all the connecting portions of the switching valve 40 are separated from each other. In this condition, as a result, the fluid cannot flow from the inlet 28 to the outlet 30 and vice versa. This switching state particularly corresponds to the third switching state described above. This can be done especially in the absence of current in the switching valve 40.

In the switching state (b) of the switching valve 40, the operating pump portions are connected in parallel. At that time, the switching valve 46 is opened. In this state, that is, due to the high inlet pressure, high suction performance can be achieved.

In the switching state (c), the actuating pump portions 42 and 44 are connected in series on the contrary. Therefore, the switching valve 46 is closed, which is indicated by a horizontal line. This switching state is preferably selected at low inlet pressures. It seems that a particularly low final pressure can be achieved.

The switching valve 40, on the one hand, switches between series and parallel operation for improved performance, and at the same time, on the other hand, functions as a safety valve. Despite its structurally simple configuration, it is possible to achieve a variety of benefits, as described here. Due to the development of the vacuum pump 10 of FIGS. 1 and 2, when the present invention is referred to, the safety valve 20 and the control pump portions 18 and 19 for pressure control of the safety valve 20 are omitted, especially due to the safety function of the switching valve. It is possible.

10 Vacuum pump 12 Rotor 14 Slider of the first working pump part 15 Transfer space of the first working pump part 16 Slider of the second working pump part 17 Transfer space of the second working pump part 18 Slider of the control pump part 19 Conveyance space for control pump part 20 Safety valve 24 Accommodation part 26 Motor 27 Coupling 28 Inlet 30 Outlet 32 Outer side surface 40 Switching valve 42 Operating pump part 44 Operating pump part 46 Switching valve SP Transition of suction performance in parallel operation SR Suction performance in series operation Transition

Claims (10)

In a vacuum pump having one first working pump part (42), at least one second working pump part (44), and a control device (40,46), the control device causes the working pump parts to be connected in series. It is possible to switch between parallel connections,
The controller has only a switching valve (40) and
The switching valve (40) has at least two switching states, one of which is assigned to the series connection and the other to the parallel connection.
The switching valve (40) has at least one third switching state, in which the working pump portion (42, 44) is separated from the vacuum pump inlet (28) .
That one drive unit for at least one actuating pump portion (42, 44) has one DC motor, which DC motor is electrically connected in series with the switching valve (40). A featured vacuum pump. The vacuum pump according to claim 1, wherein the vacuum pump is a rotary discharge type vacuum pump or a rotary vane pump. Claim 1 or claim 1, wherein the control device (40, 46) is formed to perform switching when a pre-given switching pressure and / or a pre-given switching pressure is achieved. 2. The vacuum pump according to 2. The vacuum pump according to claim 3, wherein the switching pressure is a gas pressure at the inlet (28) of the vacuum pump. The vacuum pump according to claim 3 or 4, wherein the switching pressure is below 1 hPA and / or above 0.01 hPA. The control device (40, 46) is formed so that the switching is performed according to the gas pressure at the inlet (28) of the vacuum pump, respectively, according to the known suction performance transition in the series connection and the parallel connection of the vacuum pump. The vacuum pump according to any one of claims 1 to 5, wherein the vacuum pump is provided. The pumping process is initiated by the parallel connection of the working pump parts (42, 44), and the suction performance of the vacuum pump is lower, or at least basically the same, in the parallel connection than the suction performance of the series-connected vacuum pump. The vacuum pump according to claim 1 to 6, wherein a control device (40, 46) is formed so as to switch the operation pump portion to a series connection. The vacuum pump according to claim 1, wherein the switching valve (40) is in a state where there is no current in the third switching state. The controller is characterized by having at least one separate valve (46), which separates the first actuating pump portion (42) from the vacuum pump outlet (30) for a series connection. The vacuum pump according to any one of claims 1 to 8 . The method for operating a vacuum pump according to claim 1 to 9 , characterized in that during the pumping process, the active pump portion is switched between series and parallel connections.

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