Method of pumping in a system of vacuum pumps and system of vacuum pumps

Abstract

The present invention relates to a pumping method in a pumping system (SP, SPP) comprising: a main lubricated rotary vane vacuum pump (3) with a gas inlet port (2) connected to a vacuum chamber (1) and a gas outlet port (4) leading into a conduit (5) before coming out into the gas outlet (8) of the pumping system (SP, SPP), a non-return valve (6) positioned in the conduit (5) between the gas outlet port (4) and the gas outlet (8), and an auxiliary lubricated rotary vane vacuum pump (7) connected in parallel to the non-return valve (6). According to this method, the main lubricated rotary vane vacuum pump (3) is activated in order to pump the gases contained in the vacuum chamber (1) through the gas outlet port (4), simultaneously the auxiliary lubricated rotary vane vacuum pump (7) is activated and continues to operate all the while that the main lubricated rotary vane vacuum pump (3) pumps the gases contained in the vacuum chamber (1) and/or all the while that the main lubricated rotary vane vacuum pump (3) maintains a defined pressure in the vacuum chamber (1). The present invention also relates to a pumping system (SP, SPP) able to be used to implement this method.

Claims

1. A pumping method in a system of vacuum pumps comprising: providing a main vacuum pump with a gas inlet port connected to a vacuum chamber and a gas outlet port leading into a conduit before coming out into a gas outlet of the system of vacuum pumps, said main vacuum pump including a motor; providing a non-return valve in the conduit between said gas outlet port and said gas outlet of the system of vacuum pumps; and providing an auxiliary vacuum pump connected in parallel to said non-return valve; activating said main vacuum pump in order to pump gases contained in the vacuum chamber through said gas outlet port and simultaneously activating said auxiliary vacuum pump; and continuing to operate said auxiliary vacuum pump all the while that said main vacuum pump pumps the gases contained in the vacuum chamber and/or all the while that said main vacuum pump maintains a defined pressure in the vacuum chamber.

2. The pumping method according to claim 1, comprising providing an outlet of said auxiliary vacuum pump that rejoins said gas outlet of the system of vacuum pumps after said non-return valve.

3. The pumping method according to claim 1, comprising providing said auxiliary vacuum pump with a nominal flow rate selected as a function of a volume of said conduit which is limited by said non-return valve.

4. The pumping method according to claim 3, comprising providing said auxiliary vacuum pump with the flow rate that is from 1/500 to of a nominal flow rate of said main vacuum pump.

5. The pumping method according to claim 1, comprising providing said auxiliary vacuum pump as single-staged or multi-staged.

6. The pumping method according to claim 1, comprising closing said non-return valve when a pressure at a suction end of said main vacuum pump is between 500 mbar absolute and a final vacuum.

7. The pumping method according to claim 1, wherein each of said main vacuum pump and said auxiliary vacuum pump is a lubricated rotary vane vacuum pump, comprising providing said main lubricated rotary vane vacuum pump with an oil separator, and said auxiliary lubricated rotary vane vacuum pump discharging the gases into said oil separator.

8. The pumping method according to claim 1, wherein each of said main vacuum pump and said auxiliary vacuum pump is a lubricated rotary vane vacuum pump, comprising providing said main lubricated rotary vane vacuum pump with an oil separator, and said auxiliary lubricated rotary vane vacuum pump being integrated in said oil separator.

9. The pumping method according to claim 1 comprising continuing to operate said auxiliary vacuum pump all the while that said main vacuum pump pumps the gases contained in the vacuum chamber.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The features and the advantages of the present invention will appear with more details within the context of the description which follows with example embodiments given by way of illustration and in a non-limiting way with reference to the attached drawings:

(2) FIG. 1 represents in a diagrammatic way a system of vacuum pumps suitable for implementation of a pumping method according to a first embodiment of the present invention;

(3) FIG. 2 represents in a diagrammatic way a system of vacuum pumps suitable for implementation of a pumping method according to a second embodiment of the present invention;

(4) FIG. 3 represents in a diagrammatic way the system of vacuum pumps according to the first embodiment, showing the feature wherein an auxiliary lubricated rotary vane vacuum pump ejects gas into an oil separator of a main lubricated rotary vane vacuum pump; and

(5) FIG. 4 represents in a diagrammatic way the system of vacuum pumps according to the second embodiment, showing the feature wherein an auxiliary lubricated rotary vane vacuum pump is incorporated in an oil separator of a main lubricated rotary vane vacuum pump.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(6) FIG. 1 represents a pumping system SP suitable for implementing a pumping method according to a first embodiment of the present invention.

(7) This system of vacuum pumps SP comprises a chamber 1, which is connected to the suction port 2 of a main lubricated rotary vane vacuum pump 3. The gas outlet port of the main lubricated rotary vane vacuum pump 3 is connected to a conduit 5. A non-return discharge valve 6 is placed in the conduit 5, which after this non-return valve continues into a gas exit conduit 8. The non-return valve 6, when it is closed, allows the formation of a space 4, contained between the gas outlet port of the main vacuum pump 3 and itself.

(8) The system of vacuum pumps SP also comprises an auxiliary lubricated rotary vane vacuum pump 7, connected in parallel to the non-return valve 6. The suction port 9 of the auxiliary lubricated rotary vane vacuum pump 7 is connected to the space 4 of the conduit 5, and its discharge port 10 is connected to the conduit 8.

(9) From the start of the main lubricated rotary vane vacuum pump 3, the auxiliary lubricated rotary vane vacuum pump 7 is also started up. The main lubricated rotary vane vacuum pump 3 suctions the gases in the chamber 1 through the port 2 connected at its inlet and compresses them to discharge them afterwards at its outlet in the conduit 5 and then through the non-return valve 6. When the closure pressure for the non-return valve 6 is reached, it closes. Starting from this moment the pumping of the auxiliary lubricated rotary vane vacuum pump 7 makes the pressure in the space 4 decrease progressively to its limit pressure. In parallel, the power consumed by the main lubricated rotary vane vacuum pump 3 decreases progressively. This takes place in a short time period, for example for a certain cycle in 5 to 10 seconds.

(10) With a clever adjustment of the flow rate of the auxiliary lubricated rotary vane vacuum pump 7 and of the closure pressure of the non-return valve 6 as a function of the flow rate of the main lubricated rotary vane vacuum pump 3 and the space of the chamber 1, it is moreover possible to reduce the time before the closure of the non-return valve 6 with respect to the duration of the evacuation cycle and thus reduce the electrical energy of the motor of the auxiliary lubricated rotary vane vacuum pump 7 during the time before the closure of the non-return valve 6. On the other hand, the advantage of simplicity gives an excellent reliability to the system as well as a lower price in comparison with similar pumps equipped with programmable automatic control and/or speed controller, controlled valves, sensors, etc.

(11) FIG. 2 represents a system of vacuum pumps SP suitable for implementation of a pumping method according to a second embodiment of the present invention.

(12) With respect to the system shown in FIG. 1, the system represented in FIG. 2 represents the controlled pumping system SPP, which further comprises suitable sensors 11, 12, 13 which control either the motor current (sensor 11) of the main lubricated rotary vane vacuum pump 3, or the pressure (sensor 13) of the gases in the space of the exit conduit of the main lubricated rotary vane vacuum pump, limited by the non-return valve 6, or the temperature (sensor 12) of the gases in the space of the exit conduit of the main lubricated rotary vane vacuum pump, limited by the non-return valve 6, or a combination of these parameters.

(13) As shown in FIG. 3 the auxiliary lubricated rotary vane vacuum pump 7 ejects the gas into an oil separator 14 of the main lubricated rotary vane vacuum pump 3. As shown in FIG. 4 the auxiliary lubricated rotary vane vacuum pump 7 is incorporated in an oil separator 14 of the main lubricated rotary vane vacuum pump 3.

(14) In effect, when the main lubricated rotary vane vacuum pump 3 starts to pump the gases of the vacuum chamber 1, the parameters, such as the current of its motor, the temperature and the pressure of the gases in the space of the exit conduit 4, begin to change and reach threshold values detected by the sensors. For the current of the motor, the threshold value can be a percentage of the maximum value measured during an evacuation cycle without activation of the auxiliary vacuum pump (for example 75%). For the temperature of the gases, measured at a place well defined in the space of the exit conduit 4, the threshold value can be a percentage (for example 80%) of the maximum value measured during an evacuation cycle without activation of the auxiliary vacuum pump. For the pressure of the gases, the threshold value (for example 100 mbar) is defined as a function in relation to the flow rates of the two pumps, the main one and the auxiliary one. After suitable time lags, specific to each parameter, the activation of the auxiliary lubricated rotary vane vacuum pump 7 is triggered. When these parameters return to the initial ranges (outside the set values), with suitable time lags, specific to each parameter, the auxiliary lubricated rotary vane vacuum pump 7 is stopped.

(15) Certainly the present invention is subject to numerous variations regarding its implementation. Although diverse embodiments have been described, it is well understood that it is not conceivable to identify in an exhaustive way all the possible embodiments. Of course replacing a described means with an equivalent means can be envisaged without departing from the scope of the present invention. All these modifications form part of the common knowledge of one skilled in the art in the field of vacuum technology.