VACUUM PUMP SYSTEM

Abstract

A vacuum pump system comprising a plurality of vacuum pumps which are connected to one another in parallel and are each connected on an inlet side to a chamber, having an outlet line which is connected on the outlet side of the vacuum pumps, and an intermediate line which connects the inlet side of at least one vacuum pump to the outlet line, wherein all the vacuum pumps are connected in parallel during a pumping-out period and at least one of the vacuum pumps is connected in parallel with the other vacuum pumps as a backing pump during an idle period.

Claims

1. A vacuum pump system having a plurality of vacuum pumps which are connected in parallel with each other and are each connected on an inlet side with a chamber, having an outlet line which is connected with the outlet side of said vacuum pumps, and an intermediate line connecting the inlet side of at least one vacuum pump with said outlet line, wherein during a pumping-out period all vacuum pumps are connected in parallel, and during an idle period the inlet side of at least one of said vacuum pumps is connected with the outlet side of the remaining vacuum pumps as a backing pump.

2. The vacuum pump system according to claim 1, wherein during the idle period the vacuum pump whose inlet side is connected with the outlet side of the remaining vacuum pumps is connected in series with the other vacuum pumps.

3. The vacuum pump system according to claim 1, wherein the outlet side of the vacuum pump is connected with the outlet line via a check valve.

4. The vacuum pump system according to claim 1, wherein in front of each of the vacuum pumps a valve is arranged, as well as in particular another valve is arranged in the intermediate line for controlling a parallel or series connection of the individual vacuum pumps with each other.

5. The vacuum pump system according to claim 1, wherein the at least one of the vacuum pumps whose inlet side is connected with the outlet side of the remaining vacuum pumps in the idle state and which is in particular connected in series with the other vacuum pumps is smaller dimensioned than the other vacuum pumps.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In the figures:

[0022] FIGS. 1 to 3 show embodiments according to examples of prior art, and

[0023] FIGS. 4 to 6 show exemplary embodiments according to the disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0024] FIG. 1 shows a vacuum pump system 1 having a lock chamber 10 and parallel-connected pumps P1-P5 each of which is connected on its inlet side with the lock chamber. In addition, the vacuum pump system 1 comprises valves V1-V5, by means of which the connection from the pump inlets of the pumps P1-P5 to the lock chamber 10 can be disconnected. The illustrated vacuum pump system is known from prior art. During a pumping-out period the valves V1-V5 are open. The pumps P1-P5 consume a lot of power during the pumping-out period and operate at full speed. The pressure in the lock chamber decreases continuously.

[0025] During an idle period the valves V1-V5 are dosed and the pumps P1-P5 operate at full speed, wherein the power consumption essentially corresponds to that of the operation at a discharge pressure and continues to be relatively high. The pressure in the lock chamber is equal to a transfer pressure.

[0026] During a hold period the valves V1-V5 are open and the pumps P1-P5 operate at a low operating pressure.

[0027] The vacuum pump system illustrated in FIG. 2 is known from prior art. The pump system is extended by a relatively largely dimensioned auxiliary pump P26 as well as by the check valves CV1-CV5.

[0028] The parallel-connected pumps P21-P25 are connected with a chamber 20. During a pumping-out period both the valves V21-V25 and the check valves CV21-CV25 are open. The inlet pressure of the additional auxiliary pump P26 is approximately equal to the outlet pressure of the auxiliary pump.

[0029] During an idle period the valves V21-V25 are closed. Subsequently, the check valves CV21-CV25 are also closed. During this operation the inlet pressure of the auxiliary pump P26 is considerably lower than the outlet pressure of the auxiliary pump P26.

[0030] FIG. 3 shows a prior art configuration of a vacuum pump system for a lock chamber 30 having small auxiliary pumps P33 and P34. An ejector pump may be selected as the auxiliary pump, for example.

[0031] During a pumping out period the valves V31 and V32 as well as the check valves CV31 and CV32 are open. The inlet pressures of the auxiliary pumps P33 and P34 are approximately equal to the outlet pressures of the auxiliary pumps P33 and P34.

[0032] During an idle period of the pump system 3 the valves V31 and V32 are closed.

[0033] The check valves CV31 and CV32 are also closed during an idle period. The outlet pressures of the auxiliary pumps P33 and P34 are substantially larger than the inlet pressures of these auxiliary pumps P33 and P34 during the idle period.

[0034] FIGS. 4 to 6 show configurations of the vacuum pump system according to the disclosure.

[0035] The vacuum pump system shown in FIG. 4 comprises five parallel-connected vacuum pumps P41, P42, P43, P44, P45. The inlets of the vacuum pumps P41, P42, P43, P44, P45 are connected with a vacuum chamber 40. Between the respective vacuum pumps P41, P42, P43, P44, P45 a valve V41, V42, V43, V44, V45 is provided. The outlet sides of the pumps P41, P42, P43, P44, P45 are connected with a common outlet 41 via check valves CV41 CV42, CV43 CV44, CV45.

[0036] In a connecting line 42 in which a valve V46 is arranged the pump P41 can be connected in series with the pumps P42, P43, P44, P45 in the exemplary embodiment of the vacuum pump system of FIG. 4.

[0037] The vacuum pump P41 which is to be used as a backing or as an auxiliary pump can generally be smaller designed than the other vacuum pumps. Thus the power consumption during the idle and/or hold operation is further reduced. FIG. 4 shows a vacuum pump system where the valves V41-V45 are open and the valve V46 is closed during a pumping-out period. In addition, the check valves CV41-CV45 are open during the pumping-out period.

[0038] During the idle period the valves V41-V45 are closed, V46 is open. The check valve CV41 is also open during this operation as long as the pump system is evacuated by the pump P41. Thereafter it is closed. The check valves CV42-CV45 are closed during the idle operation. The reduction of the power consumption in the idle state amounts to up to 40% in some exemplary embodiments. In particular, the described series connection of the vacuum pump as a backing pump can also be used for improving the feed of light gases. In addition, this pump connection can also be used for regulating the chamber pressure or the process flow. The auxiliary pump ensures that the operating pressure range is reliably reached. The backing pumps can then be reliably regulated in a very large speed range.

[0039] FIG. 5 illustrates a minimal configuration for lock chambers in the exemplary embodiment of FIG. 5 a pump system merely having two vacuum pumps P51, P52 is selected as an example. They comprise a common inlet line which is connected with a vacuum chamber 50 via a valve V52. Merely the outlet of the vacuum pump P52 is connected with the common outlet 51 via a check valve CV51. The outlet of the pump P51 is directly connected with the common outlet 51. Via an additional line 52 in which a valve V51 is arranged and which extends from the outlet of the pump P52 to the inlet of the pump P51 the pump P51 can evacuate the other pump P52 from both sides during the idle period. In the example of FIG. 5 the pumps P51 and P52 can however not be connected in series.

[0040] Similar to FIG. 5, FIG. 6 shows a minimal configuration for process chambers. During the hold period V61 is open such that P62 and P61 are evacuated from both sides. During the pumping-out period V6 is closed such that the process chamber can be evacuated within a short period of time. In both configurations of the vacuum pump systems 5 and 6 further pumps can be connected in parallel with the pumps P52 and P62 and operated accordingly.

[0041] The solutions described here can be realized for combinations with two or more backing pumps. The respective number and size of the pumps can be freely adapted to the application. The Roots pumps connected in series with the backing pumps have generally no influence on the solutions. Therefore they have net been illustrated in the examples.