Pumping system for generating a vacuum and method for pumping by means of this pumping system

Abstract

The present invention relates to a pumping system to generate a vacuum (SP), comprising a main vacuum pump which is a claw pump (3) having a gas suction inlet (2) connected to a vacuum chamber (1) and a gas discharge outlet (4) leading into a gas evacuation conduit (5) in the direction of a gas exhaust outlet (8) outside the pumping system. The pumping system comprises a non-return valve (6) positioned between the gas discharge outlet (4) and the gas exhaust outlet (8), and an auxiliary vacuum pump (7) connected in parallel to the non-return valve. In a pumping method by means of this pumping system (SP), the main vacuum pump (3) is started up in order to pump the gases contained in the vacuum chamber (1) and to discharge these gases through its gas discharge outlet (4), simultaneously to which the auxiliary vacuum pump (7) is started up. Moreover the auxiliary vacuum pump (7) continues to pump all the while that the main vacuum pump (3) pumps the gases contained in the vacuum chamber (1) and/or all the while that the main vacuum pump (3) maintains a defined pressure in the vacuum chamber (1).

Claims

1. Pumping system for generating a vacuum, comprising a main vacuum pump having a gas suction inlet connected to a vacuum chamber and a gas discharge outlet leading into a gas evacuation conduit in the direction of a gas exhaust outlet outside the pumping system, wherein the pumping system comprises a non-return valve positioned between the gas discharge outlet and the gas exhaust outlet, and an auxiliary vacuum pump connected in parallel to said non-return valve, wherein said auxiliary vacuum pump comprises a discharge end which is connected downstream from said non-return valve to the gas exhaust outlet, wherein said auxiliary vacuum pump is an ejector; and a compressor driven by said main vacuum pump that provides flow of gas at a pressure suitable for operation of said ejector; said main vacuum pump and said auxiliary vacuum pump are started simultaneously and said auxiliary vacuum pump operates all the while that said main vacuum pump operates and/or all the while that said main vacuum pump maintains a defined pressure in the vacuum chamber.

2. Pumping system according to claim 1, wherein nominal flow rate of said auxiliary vacuum pump is selected as a function of the inner volume of the gas evacuation conduit between said main vacuum pump and said non-return valve.

3. Pumping system according to claim 2, wherein said auxiliary vacuum pump is single-staged.

4. Pumping system according to claim 1, wherein the nominal flow rate of said auxiliary vacuum pump is from 1/500 to 1/5 of the nominal flow rate of said main vacuum pump.

5. Pumping system of claim 1 excluding a pressure sensor.

6. Pumping method by means of a pumping system, comprising providing a pumping system for generating a vacuum, comprising: a main vacuum pump having a gas suction inlet connected to a vacuum chamber and a gas discharge outlet leading into a gas evacuation conduit in the direction of a gas exhaust outlet outside the pumping system; a non-return valve positioned between the gas discharge outlet and the gas exhaust outlet; an auxiliary vacuum pump connected in parallel to said non-return valve, wherein said auxiliary vacuum pump comprises a discharge end which is connected downstream from said non-return valve to said gas exhaust outlet, wherein said auxiliary vacuum pump is an ejector; and a compressor driven by said main pump that provides flow of gas at a pressure suitable for operation of said ejector; starting up said main vacuum pump in order to pump the gases contained in the vacuum chamber and to discharge these gases through said gas discharge outlet and simultaneously starting up said auxiliary vacuum pump; and wherein said auxiliary vacuum pump continues to pump all the while that the 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.

7. Pumping method according to claim 6, wherein said auxiliary vacuum pump pumps at a flow rate on the order of 1/500 to 1/20 of the nominal flow rate of said main vacuum pump.

8. Pumping method according to claim 7, comprising closing said non-return valve when the pressure at the suction end of said main vacuum pump is less than 500 mbar absolute.

9. Pumping method of claim 6 excluding a pressure sensor.

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 pumping system suitable for implementation of a pumping method according to a first embodiment of the present disclosure;

(3) FIG. 2 represents a pumping system SPP suitable for implementation of a pumping method according to a second embodiment of the present invention;

(4) FIG. 3 represents in a diagrammatic way a pumping system suitable for implementation of a pumping method according to another embodiment of the present disclosure including a compressor feeding air to an ejector; and

(5) FIG. 4 represents in a diagrammatic way a pumping system suitable for implementation of a pumping method according to another embodiment of the present disclosure including a compressor powered by the main pump which feeds air to an ejector.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

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

(7) This pumping system SP comprises a chamber 1, which is connected to the suction end 2 of a main vacuum pump constituted by a claw pump 3. The gas discharge outlet of the main claw vacuum pump 3 is connected to an evacuation conduit 5. A non-return discharge valve 6 is placed in the evacuation conduit 5, which, after this non-return valve, continues into the gas exit conduit 8. The non-return valve 6, when it is closed, permits the formation of a volume 4, contained between the gas discharge outlet of the main vacuum pump 3 and itself.

(8) The pumping system SP also comprises the auxiliary vacuum pump 7, connected in parallel to the non-return valve 6. The suction end of the auxiliary vacuum pump is connected to the space 4 of the evacuation conduit 5 and its discharge end is connected to the conduit 8.

(9) Already with the actuation of the main claw vacuum pump 3, the auxiliary vacuum pump 7 is itself actuated. The main claw vacuum pump 3 suctions the gases in the chamber 1 through the conduit 2 connected at its inlet and compresses them in order to discharge them subsequently at its exit in the evacuation conduit 5 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 vacuum pump 7 makes the pressure in the space 4 drop progressively to the value of its pressure limit. In parallel, the power consumed by the main claw vacuum pump 3 decreases progressively. This takes place in a short time period, for example for a certain cycle in 5 to 10 seconds as a function of the relationship between the volume 4 and the nominal flow rate of the auxiliary vacuum pump 7, but can also last longer.

(10) With a clever adjustment of the flow rate of the auxiliary vacuum pump 7 and of the closure pressure of the non-return valve 6 as a function of the flow rate of the main claw vacuum pump 3 and the volume 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 quantity of energy consumed during this time of operation of the auxiliary pump 7, with the advantage of simplicity and of reliability of the system.

(11) According to the different possibilities of combination, the auxiliary vacuum pump 7 can be another claw pump, a dry pump of screw type, a multi-stage Roots pump, a diaphragm pump, a dry rotary vane pump, a lubricated rotary vane pump or even an ejector. In the last case, the ejector can be a simple ejector in the sense that the flow rate of its propellant gas comes from a distribution network on the industrial site, or can be equipped with a compressor 10 which provides to the ejector the flow of propellant gas at the pressure necessary for its operation (FIGS. 3 and 4). More specifically, this compressor 10 can be driven by the main pump (FIG. 4) or, alternatively or in addition, in an autonomous way, independently of the main pump. This compressor can suction the atmospheric air or gases in the gas exit conduit after the non-return valve. The presence of such a compressor renders the system of pumps independent of a source of compressed gas, which can meet requirements of certain industrial environments.

(12) FIG. 2 represents a pumping system SPP suitable for implementation of a pumping method according to a second embodiment of the present invention.

(13) With respect to the system shown in FIG. 1, the system shown in FIG. 2 represents the controlled pumping system SPP, may further comprise suitable sensors 11, 12, 13 which check either the current of the motor (sensor 11) of the main claw vacuum pump 3, or the pressure (sensor 13) of the gases in the space of the exit conduit of the main claw vacuum pump, limited by the non-return valve 6, or the temperature (sensor 12 of the gases in the space of the exit conduit at the exit of the main claw vacuum pump, limited by the non-return valve 6, or a combination of these parameters. In effect, when the main claw vacuum pump 3 begins 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. After a time lag, this causes the startup of the auxiliary vacuum pump 7. When these parameters return to the initial ranges (outside the set values), with a time lag the auxiliary vacuum pump is stopped.

(14) In the second embodiment of the invention of FIG. 2, the auxiliary vacuum pump can also be of claw type, of dry screw type, multi-stage Roots type, diaphragm type, dry rotary vane type, lubricated rotary vane type, or an ejector (with or without compressor providing its propellant gas), as in the first embodiment of FIG. 1.

(15) 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.