Abstract:
A pumping system includes a chamber ( 10 ) having an intake orifice ( 11 ) for introducing liquid into said chamber ( 10 ). A discharge orifice ( 12 ) discharges the liquid from the chamber ( 10 ). Another orifice ( 13 ) receives pressurized gas. A valve is located at each of the orifices ( 11, 12, 13 ). The valves ( 15, 16, 17 ) are controlled in synchronization according to two phases. During the first phase the valve ( 15 ) opens at the intake orifice ( 11 ) while the other two valves ( 16  and  17 ) are closed, in order to fill the chamber ( 10 ). During a second phase the valve ( 15 ) associated with the intake orifice ( 11 ) is closed while the other two valves ( 16  and  17 ) are open, this enabling pressurized gas to be introduced into the chamber ( 10 ), thereby expelling the liquid in the chamber ( 10 ) through the discharge orifice ( 12 ).

Description:
The present invention concerns a liquid pumping system. Such a pumping system can work as a pump with various liquids. One application of such a pumping system can consist of a liquid gun, such as for water, which can project a liquid at a great distance and at a controllable rate, for example for watering plants or as a water cannon for use against fire or riots. 
     BACKGROUND OF THE INVENTION 
     In order to spray a liquid, use is generally made of centrifugal pumps which are coupled to a thermal engine. The drawback of such pumps is that they require a relatively high power. For example, a centrifugal pump which has an output of 1300 liters/minute at a pressure of 12 bar requires, for the thermal engine in which drives this, a power of 120 continental horsepower. 
     The aim of the invention is to propose a liquid pumping system which considerably reduces this power required for spraying said liquid, for example in a ratio of 8 to 10. 
     BRIEF SUMMARY OF INVENTION 
     To this end, a system for pumping a liquid according to the invention is characterised in that it consists of a chamber provided with an orifice for introducing, into the chamber, a liquid issuing from a source, an orifice for discharging the liquid out of the chamber and an orifice opposite to the orifice for discharging the liquid for introducing pressurised gas, each orifice being provided with a valve, the valves being controlled in a synchronized fashion according to two phases, a first so-called filling phase in which the valve associated with the introduction orifice is open whilst the other two valves are closed, thus enabling the chamber to be filled, and a second so-called expulsion phase in which the valve associated with introduction orifice is closed whilst the other two valves are open enabling pressurised gas to be introduced into the chamber through the introduction orifice, thus expelling the liquid contained in the chamber through the discharge orifice. 
     According to another characteristic of the invention, the chamber is provided with a vent opposite to the liquid introduction orifice, the vent itself being provided with a valve which opens and closes at the same time as the valve associated with the liquid introduction orifice. 
     According to another characteristic of the invention, alternative to the previous one, the chamber is provided with an orifice connected, via a valve, to a vacuum pump, the valve opening and closing at the same time as the valve associated with the liquid introduction orifice. 
     According to another characteristic of the invention, the valve associated with the introduction orifice is situated at the end of the chamber which is provided with the discharge orifice, the vent being situated at the other end. 
     According to another characteristic of the invention, it has means for detecting liquid levels in the said chamber, whose signals are supplied to a control unit designed to be able to control the opening and closing of the valves. 
     According to another characteristic of the invention, the chamber has, on the same side as its discharge orifice, a tapered part narrowing towards the discharge orifice. 
     The present invention also concerns a set of pumping system s in accordance with a pumping system as just described. According to the invention, it is characterised in that each system is controlled so that the discharge phases of each discharge system follow one after the other, and in that, whilst that of one system is current, filling phases are implemented in the other systems. 
     According to another characteristic of this set, the number n of discharge systems in the set is such that n times the discharge time correspond to a filling time. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The characteristics of the invention mentioned above, as well as others, will emerge more clearly from a reading of the following description of an example embodiment, the description being given in relation to the accompanying drawings, amongst which: 
     FIG. 1 is a diagram showing a water pumping installation using a pumping system according to the invention, 
     FIG. 2 Is a diagram showing a water pumping installation using a pumping system according to a variant of the invention, 
     FIG. 3 shows a diagram of a body of a pumping system according to the invention in a particular embodiment. 
     FIG. 4 is a diagram of a set of pumping systems according to the invention, and 
     FIG. 5 is a diagram illustrating the functioning of a set in accordance with that of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF INVENTION 
     The installation depicted in FIG. 1 consists essentially of a pumping system according to the invention  100 , a liquid source  20  and a compression pump  30  intended to supply a gas at a relatively high pressure. For example, this gas is air. 
     The pumping system  100  which can be seen in this FIG. 1 consists essentially of a body forming in its interior a closed chamber  10 , for example but not necessarily cylindrical. The body  10  is provided with an orifice  11  intended for introducing liquid from the source  20  into the chamber of the body  10  and an orifice  12  for discharging, out of the chamber of the body  10 , the liquid which it contains. In the example embodiment depicted, the introduction orifice  11  and a discharge orifice  12  are situated in the lower part of the body  10 , which has a longitudinal axis which is vertical. 
     This body  10  is also provided with an orifice  13  which is opposite the orifice for discharging the said liquid  12  and which is designed to allow the introduction, into the chamber of the body  10 , of the gas under high pressure supplied by the compression pump  30 . 
     The body  10  is also provided with a vent  14  which is situated opposite the introduction orifice  12 . 
     The pumping system  100  also has a valve  15  placed on the pipe between the source  20  and the introduction orifice  11 , a valve  16  placed on the discharge orifice  12 , a valve  17  placed on the pipe between the pump  30  and the introduction orifice  13  and a valve  18  placed on the vent  14 . 
     The valves  15  to  18  are controlled in synchronism by means of a control unit  40  which also receives the signals on the one hand from a low-level detector  42  and on the other hand from a high-level detector  41 . 
     The pumping system  100  according to the invention functions as follows. 
     In a first phase referred to as the filling phase, the chamber of the body  10  is filled with a volume of liquid issuing from the source  20 . To do this, the introduction valve  15  and the valve of the vent  18  are opened, the gas introduction valve  13  and the discharge valve  16  for their part being closed. The liquid issuing from the source  20  enters by gravity into the chamber of the body  10 , via the introduction orifice  11 . Filling takes place until the liquid reaches the level of the high detector  41 , which transmits a signal to the control unit  40 , which triggers the closure of the valves  15  and  18 . 
     It will be noted that the vent  14  serves for the discharge of the air which is driven from the chamber of the body  10  by its filling with liquid. 
     In a second phase, referred to as the discharge phase, the gas introduction valve  17  is open, as is the discharge valve  16 . As a result, at the surface of the liquid which is opposite to the orifice  12  there is a gas pressure given by the pump  30  which has the effect of pressing on this surface and affording the discharge of the liquid through the orifice  12 . The liquid is expelled and sprayed in the form of a high-power jet. 
     It should be noted that, according to a preferred mode, the second phase commences immediately after the end of the first phase. Consequently the valves  16  and  17  open as soon as the valves  15  and  18  close. 
     It should be noted that the opening of the valves  16  can be slightly delayed with respect to the opening of the valves  17 . 
     When the liquid level corresponds to that of the low detector  42 , a signal is transmitted to the control unit  40 , which triggers the closure of the valves  16  and  17 . The control unit  40  can then once again trigger the first phase of the process. 
     With such a system, the consumed power necessary for its functioning was around  11  continental horsepower whereas, in order to have the same performance with regard to pressure and output of the water jet obtained, a power of 120 continental horsepower is necessary with a centrifugal pump. 
     In the example embodiment in FIG. 2, the vent  14  is replaced by an orifice  14  connected, via the valve  18 , to a suction pump  50 . The functioning is similar to that of the example embodiment depicted in FIG. 1, except that the liquid from the source  20  is no longer introduced by gravity but by producing a vacuum in the chamber of the body  10  by means of the suction pump  50 . 
     It should also be noted that the detectors  41  and  42  could be replaced by a pressure switch which, when the pressure in the body  10  reaches, whilst increasing, an upper limit valve, demands the closure of the valves  15  and  18  and which, when the pressure in the body  10  reaches, in falling, a lower limit value, demands the closure of the valves  16  and  17 . 
     FIG. 3 depicts a body  10  of a pumping system according to the invention with its introduction orifices  11  and  13  and its discharge orifice  12  a nd its vent (or suction orifice)  14 . This body  10  has the particularity of comprising, in its lower part, a tapered part  10   a  narrowing towards the discharge orifice  12 . It was possible to show that this characteristic was advantageous for obtaining a fine atomisation at the end of the jet because of the mixing of water and gas which takes place at the end of discharge. 
     FIG. 4 depicts an installation with n pumping systems  101  to  10   n  identical to the first embodiment depicted in F ig  1 . It should be noted however that the said systems could be identical to the second embodiment in FIG.  2 . In this FIG. 4, the valves  15  to  18  of each system  101  to  10   n  have not been depicted for reasons of clarity in FIG.  4 . 
     The source  20  is therefore connected to the n introduction inlets  11  of the n pumping systems  101  to  10   n , via n respective valves  15  (see FIG.  1 ). Likewise, the compression pump  30  is connected to the n pressurised gas introduction inlets  13  of the n pumping systems  101  to  10   n , via n respective valves  17  (see FIG. 1) and the n discharge orifices  12  are connected to an outlet S. The vents  14  should be noted, which are also connected to respective valves  18  (see FIG.  1 ). 
     The control unit  40  controls each system  10   i  (i being able to vary from 1 to n) as indicated above, that is to say according to two phases, a filling phase I and a discharge phase II, phases which are triggered and interrupted after reception of the level signals issuing from the detectors  41  and  42  of each system  10   i . FIG. 5 depicts how these phases I and II unfold over time for each pumping system of an installation which has three of them (n=3). It will be noted that, in this FIG. 5, that the duration of the filling phase I is greater than of the discharge phase II. 
     At time t 0 , the system  101  begins to fill, the system  102  discharges and the system  103  finishes filling. At time t 1 , the system  101  is still filling, the system  102  has finished discharging and is beginning to fill and the system  103  is beginning to discharge. At time t 2 , the system  101  finishes filling and begins to discharge, the system  102  is still filling and the system  103  has finished discharging and is beginning its filling. 
     It should be noted that the discharge phases II follow one after the other, and that, whilst that of one system is current, filling phases are implemented in the other systems. Advantageously, a number n of systems will be chosen such that n times the duration of the discharge phase II correspond to that of the filling phase I. This is because, in this case, the output at the outlet S is substantially constant.