GB2220710A

GB2220710A - Fluidic pumps

Info

Publication number: GB2220710A
Application number: GB8811846A
Authority: GB
Inventors: Geoffrey Hugh Priestman
Original assignee: UK Atomic Energy Authority
Current assignee: UK Atomic Energy Authority
Priority date: 1988-05-19
Filing date: 1988-05-19
Publication date: 1990-01-17
Also published as: GB8811846D0

Abstract

A fluidic pump comprises a two-diode pump (10-12) having a first displacement vessel (12), a third diode 13 connected to receive output from the two-diode pump through a delivery line 14 and discharge to an outlet 15, and a second displacement vessel 16 connected to the delivery line 14. There is a feed tank 19 at a greater height than the two-diode pump, and a drive unit 21, 22 for alternately pressurising and venting the first and second displacement vessels. The drive pressure required to operate the pump can be of the order of half that for a single stage 2-diode pump. <IMAGE>

Description

Fluidic Pumps This invention relates to fluidic pumps.

According to this invention a fluidic pump comprises a two-diode pump having a first displacement vessel, a third diode connected to receive output from the two-diode pump through a delivery line and discharge to an outlet, and a second displacement vessel connected to the delivery line.

The pump may include a feed tank at a greater height than the two-diode pump, and a drive unit for alternately pressurising and venting the first and second displacement vessels.

The invention may be performed in various ways and some specific embodiments will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a 3-diode pump; Figure 2 shows a 4-diode pump; and Figure 3 shows an N + 2 diode pump.

The invention relates to fluidic diode pumps, the simplest having three diodes but more complex ones having four, five, six or more diodes.

The basic design of the three diode pump is shown in Figure 1. Diodes 10 and 11 can be regarded as forming a standard 2-diode pump with a single displacement vessel 12. A third diode 13 is positioned on the delivery pipe 14 between diode 11 and the discharge point 15. This diode 13 also has a single displacement vessel 16 which is connected to the delivery pipe 14 via pipe 17 at 18 between diodes 11 and 13. In effect, the 3-diode pump can be regarded as a pair of multistaged 2-diode pumps in which the outlet diode of the first stage (diode 11) also forms the inlet diode of the second stage.

The pump can be operated in several ways. The simplest is when the first stage is submerged sufficiently beneath a feed tank 19 that it fills through pipe 20 due to gravity with no suction required. The pump can therefore be operated by alternately pressurising and venting the two displacement vessels 12, 16. Thus when displacement vessel 12 is pressurised, displacement vessel 16 is vented and filled from the delivery pipe 14, and when displacement vessel 12 is vented and refilled, displacement vessel 16 drives a net flow of liquid to the discharge point 15. This drive action can be achieved by a free running all-fluidic drive unit 21, with vented bistable amplifier 22, of the type used for double-acting pumps or by a suitable electromechanical controller, air pipes being shown at 23, 24.A major advantage of this design is that the drive pressure required to operate the pump can be of the order of half that required for a single stage 2-diode pump of the same lift. This is because vessel 12 need only drive to vessel 16, which can be half way up the delivery pipe 14, and vessel 16 then has half the total lift remaining to the discharge point 15. This therefore significantly extends the potential range of lifts attainable with all-fluidic controllers. If the pump must be operated with suction-aided refill of vessel 12, this can be achieved by giving a negative pressure bias to the controller described above. Alternatively, vessel 12 could be operated with a conventional drive unit, perhaps with level control. This would be phase linked to a controller driving vessel 16.

This type of multistage diode pump design can be extended to include 4, 5, 6 ... N + 2 diodes with 3, 4, 5 ... N + 1 displacement vessels. Figure 2 shows a 4-diode design and Figure 3 is a general N + 2 diode design.

These pumps can be operated in a similar manner to the 3-diode pump. For 5, 7 ... 2 N + 1 designs free running fluidic controllers (of the double-acting pump type), suitably phased, could be used with each successive pair of displacement vessels. Alternatively, these and the other designs could be operated with suitably a linked electromechanical controller. As with the 3-diode design, these multistaged pumps divide the effective pump head into parts which can then be attained with a proportionally reduced drive pressure.

The stable operation of these multi-diode pumps is ensured by correct relative sizing of the diodes and displacement vessels combined with a suitable operating cycle.

Claims

1. A fluidic pump comprising a two-diode pump having a first displacement vessel, a third diode connected to receive output from the two-diode pump through a delivery line and discharge to an outlet, and a second displacement vessel connected to the delivery line.

2. A fluidic pump as claimed in Claim 1, including a feed tank at a greater height than the two-diode pump, and a drive unit for alternately pressurising and venting the first and second displacement vessels.

3. A fluidic pump substantially as hereinbefore described with reference to and as shown in Figure 1, or Figure 2, or Figure 3, of the accompanying drawings.