GB2122262A - Improvements in and relating to fluidic pumps - Google Patents

Abstract

A fluidic pump including a reverse flow diverter (RFD) located at a position below the level of a liquid to be pumped. The RFD comprises two conical nozzles 1, 2 separated by a gap 3 which opens into the liquid to be pumped. During pumping it is possible that sediment or debris will be drawn through the gap into the nozzles of the RFD resulting in blockage rendering the pump inoperable and ineffective. To overcome this problem a pressure fluid is directed through a pipe 10 into the gap between the nozzles to flush out sediment or debris as it collects in the gap. The pressure fluid can be water or air. <IMAGE>

Description

SPECIFICATION Improvements in and relating to fluidic pumps The present invention concerns fluidic pumps.

Fluidic pumps incorporating RFD's (reverse flow diverters) are known. Basically, a RFD is a venturi-like device comprising two conical diffusers separated by a gap. The nozzles of the diffusers are opposed to each other and separated by the gap which opens into a liquid to be pumped or lifted. On coupling a cylinder to the end of one diffuser remote from the gap the application of reciprocating pressure to the cylinder causes the liquid to be alternately drawn into the cylinder through the gap and pumped across the gap and through an outflow pipe connected to the end of the other diffuser remote from the gap.

With the RFD located within a tank difficulties can arise if sediment accumulates at the bottom of the tank to cover the RFD. In such a situation the sediment can be drawn into the nozzles of the diffusers and can result in blockage rendering the pump inoperable and ineffective. The present invention seeks to avoid such difficulties.

According to the present invention there is provided a fluidic pump incorporating a RFD as described and comprising means for directing a separate supply of fluid to the gap between the nozzles of the diffusers.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic elevation of an embodiment of a fluidic pump according to the invention; and Figure 2 is a schematic elevation of an alternative embodiment.

In Figure 1, a fluidic pump comprises a RFD having two conical diffusers 1 and 2 separated by a gap 3. The RFD is located at the bottom of a tank 4 and the contents of the tank communicate with the gap 3 from below and as depicted by the arrows. The diffuser 1 is coupled to a cylinder 5 which is connected to a supply of high pressure air in line 6. The diffuser 2 is coupled to an outflow pipe 7 leading to a tank 8.

The contents of the tank 4 can be pumped to the tank 8 as follows. Pressure is first released from the cylinder 5 to allow fluid in the tank 4 to pass into the gap 3 and along the diffuser 1 into the cylinder 5. On application of pressure to the cylinder 5 the fluid therein is forced out through the diffuser 1, across the gap 3 and through the diffuser 2 and the pipe 7 to the tank 8. A pressure drop at the gap 3 causes fluid in the tank 4 to flow into the gap and entrained with the flow to the tank 8. During the reverse flow, fluid in the pipe 7 flows back to the cylinder 5 through the RFD and also effects entrainment from the tank 4.

Under operational conditions the RFD can be immersed under sediment at the bottom of tank 4. Such sediment can be a bed of sand 9 and in such cases the sand is drawn into the RFD which can become blocked and inoperative. To counter the accumulation of sand (or other sediment) within the RFD a pressure fluid is applied through pipe 10 to the gap 3. The effect is to fluidise the sand (or other sediment) in the gap whereby to prevent blockage of the RFD.

The pump in Figure 1 delivers an intermittent flow to the tank 8. In Figure 2 the out-flow along line 11 is continuous by utilising two pressure cylinders 1 2 acting in alternation to cause a forward flow in one RFD and a reverse flow in the other RFD. Each RFD provides an intermittent out of phase supply to the line 11 and the two RFD's combine to maintain a substantially continuous outflow. Again to prevent sediment accumulating in and blocking the RFD's a supply of pressure fluid can be directed into the gap of each RFD along lines 13.

The fluid supplied along iines 10 and 13 can be water.

Claims (Filed on 26 May 83) 1. A fluidic pump comprising a reverse flow diverter as herein described and including means for directing a pressure fluid to the gap between the nozzles of the diffusers to prevent the accummulation of sediment in the gap.

2. A fluidic pump as claimed in claim 1 in which the pressure fluid directing means comprises a pipe in communication with the gap.

3. A fluidic pump as claimed in claim 1 or 2 in which the pressure fluid comprises water.

4. A fluidic pump substantially as herein described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in and relating to fluidic pumps The present invention concerns fluidic pumps. Fluidic pumps incorporating RFD's (reverse flow diverters) are known. Basically, a RFD is a venturi-like device comprising two conical diffusers separated by a gap. The nozzles of the diffusers are opposed to each other and separated by the gap which opens into a liquid to be pumped or lifted. On coupling a cylinder to the end of one diffuser remote from the gap the application of reciprocating pressure to the cylinder causes the liquid to be alternately drawn into the cylinder through the gap and pumped across the gap and through an outflow pipe connected to the end of the other diffuser remote from the gap. With the RFD located within a tank difficulties can arise if sediment accumulates at the bottom of the tank to cover the RFD. In such a situation the sediment can be drawn into the nozzles of the diffusers and can result in blockage rendering the pump inoperable and ineffective. The present invention seeks to avoid such difficulties. According to the present invention there is provided a fluidic pump incorporating a RFD as described and comprising means for directing a separate supply of fluid to the gap between the nozzles of the diffusers. The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic elevation of an embodiment of a fluidic pump according to the invention; and Figure 2 is a schematic elevation of an alternative embodiment. In Figure 1, a fluidic pump comprises a RFD having two conical diffusers 1 and 2 separated by a gap 3. The RFD is located at the bottom of a tank 4 and the contents of the tank communicate with the gap 3 from below and as depicted by the arrows. The diffuser 1 is coupled to a cylinder 5 which is connected to a supply of high pressure air in line 6. The diffuser 2 is coupled to an outflow pipe 7 leading to a tank 8. The contents of the tank 4 can be pumped to the tank 8 as follows. Pressure is first released from the cylinder 5 to allow fluid in the tank 4 to pass into the gap 3 and along the diffuser 1 into the cylinder 5. On application of pressure to the cylinder 5 the fluid therein is forced out through the diffuser 1, across the gap 3 and through the diffuser 2 and the pipe 7 to the tank 8. A pressure drop at the gap 3 causes fluid in the tank 4 to flow into the gap and entrained with the flow to the tank 8. During the reverse flow, fluid in the pipe 7 flows back to the cylinder 5 through the RFD and also effects entrainment from the tank 4. Under operational conditions the RFD can be immersed under sediment at the bottom of tank 4. Such sediment can be a bed of sand 9 and in such cases the sand is drawn into the RFD which can become blocked and inoperative. To counter the accumulation of sand (or other sediment) within the RFD a pressure fluid is applied through pipe 10 to the gap 3. The effect is to fluidise the sand (or other sediment) in the gap whereby to prevent blockage of the RFD. The pump in Figure 1 delivers an intermittent flow to the tank 8. In Figure 2 the out-flow along line 11 is continuous by utilising two pressure cylinders 1 2 acting in alternation to cause a forward flow in one RFD and a reverse flow in the other RFD. Each RFD provides an intermittent out of phase supply to the line 11 and the two RFD's combine to maintain a substantially continuous outflow. Again to prevent sediment accumulating in and blocking the RFD's a supply of pressure fluid can be directed into the gap of each RFD along lines 13. The fluid supplied along iines 10 and 13 can be water. Claims (Filed on 26 May 83)

1. A fluidic pump comprising a reverse flow diverter as herein described and including means for directing a pressure fluid to the gap between the nozzles of the diffusers to prevent the accummulation of sediment in the gap.

2. A fluidic pump as claimed in claim 1 in which the pressure fluid directing means comprises a pipe in communication with the gap.

3. A fluidic pump as claimed in claim 1 or 2 in which the pressure fluid comprises water.

4. A fluidic pump substantially as herein described with reference to and as illustrated in the accompanying drawings.