Pumps – Diverse pumps – Series
Patent
1990-08-14
1991-08-13
Smith, Leonard E.
Pumps
Diverse pumps
Series
417 2, F04B 2308
Patent
active
050392808
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a pump assembly for obtaining a high vacuum.
It is well known that in order to obtain pressures of less than 10.sup.-3 mbar, a primary pump is associated in series with a secondary pump. When the assembly is started up, only the primary pump is run until the pressure upstream from the primary pump has dropped to a value P.sub.1 enabling the secondary pump to operate. The secondary pump is then started and both pumps, i.e. the primary pump and the secondary pump operate simultaneously, in series, and permanently. The desired pressure in the enclosure is thus achieved after some length of time has elapsed.
Such a pumping assembly requires electricity to feed the motors driving the pumps. The electricity may be taken either from a mains supply or else from a storage battery integrated in the pumping assembly.
The object of the invention is to economize the electrical energy consumed during pumping operations. The invention is particularly advantageous for portable assemblies which are powered, in particular, from storage batteries, the invention making is possible to increase the running time of the pumping assembly for a battery of given size and weight.
The present invention thus provides a pumping assembly for obtaining a high vacuum, the assembly comprising a primary pump and a secondary pump associated in series, the inlet of the secondary pump being taken from an enclosure to be evacuated, the assembly further including means for starting the secondary pump when the pressure upstream from the primary pump drops below a value P.sub.1, the assembly being characterized in that a passive tank followed by an isolating valve are interposed between the outlet from the secondary pump and the inlet to the primary pump, and in that it includes control means for closing the isolating valve and stopping the primary pump when the pressure in said passive tank reaches a value P.sub.2 <P.sub.1, and for opening the isolating valve and restarting the primary pump when the pressure in said passive tank returns to the pressure P.sub.1.
An embodiment of the invention is now described by way of example with reference to the accompanying drawing, in which:
FIG. 1 is a block diagram of a pumping assembly in accordance with the invention; and
FIG. 1 is thus a block diagram of a pumping assembly comprising a secondary pump 1 having a drive motor 2 having its inlet side connected to an enclosure in which a high vacuum is desired, and having its outlet side connected to a primary pump 4 having a drive motor 5, said primary pump 4 outputting to the atmosphere.
The pumping assembly shown is, for example, portable and cordless, and therefore includes a storage battery 6 for powering the assembly. The battery feeds an electrical control circuit 7 which includes, inter alia, a DC-AC converter for providing a 3- phase AC to the motors 2 and 5. Lines 8 and 9 represent these power supply connections.
As is known, the secondary pump 1 cannot operate unless below a certain pressure P.sub.1 referred to as the priming pressure. Thus, when the assembly is initially started, only the primary pump 4 is switched on, and the secondary pump is started automatically when the pressure upstream from the primary pump falls below said pressure P.sub.1. It is known that the current taken by the drive motor 5 is an increasing function of inlet pressure. Thus, the secondary pump is switched on when the current taken by the drive motor 5 drops below a value which corresponds to said priming pressure P.sub.1. To this end, the control circuit 7 includes a current-sensitive relay, for example, switching at a predetermined value of the current taken by the line 9.
According to the invention, a passive tank 10 followed by an isolating valve 11 are interposed between the outlet 12 from the secondary pump 1 and the inlet 13 to the primary pump 4. The passive tank 10 is merely a cavity having a certain volume, that is why it is called "passive".
The control circuit 7 includes a relay which operates between two values of the curr
REFERENCES:
patent: 2492075 (1949-12-01), Van Atta
patent: 4770609 (1988-09-01), Uchida et al.
Long Jacques
Saulgeot Claude
Alcatel Cit
Freay Charles G.
Smith Leonard E.
LandOfFree
Pump assembly for obtaining a high vacuum does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pump assembly for obtaining a high vacuum, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pump assembly for obtaining a high vacuum will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1524525