GB2130302A

GB2130302A - Rotary positive-displacement pump

Info

Publication number: GB2130302A
Application number: GB08328529A
Authority: GB
Inventors: Brian Howard Glover
Original assignee: GRUNDY
Current assignee: GRUNDY
Priority date: 1982-10-28
Filing date: 1983-10-25
Publication date: 1984-05-31
Also published as: GB2130302B; PT77575B; ES8407456A1; ES526820A0; EP0110552A1; PT77575A; GB8328529D0

Description

1 GB 2 130302A 1

SPECIFICATION

Improvements in or relating to pumps for dispensing beverages This invention relates to an improved pump princially for use in dispensing beverages such as beer, the pump being provided in the flow line from the cask containing the beverage to the dispense point tap. This invention is more specifically concerned with a so-called helix pump of the kind having an eccentrically mounted rotor which together with an annular wall of the pump casing forms a pumping chamber. The eccentric member is moved by a crankshaft and the point of contact with the annular wall sweeps the chamber causing fluid to be drawn in through an inlet to the chamber and forced out through an outlet.

The rotor is constrained against rotational movement relative to the chamber within the casing and through the eccentric action of a central hub moves its point of contact with the pump casing around the annular wall. In a preferred construction two rotors are provided which are phased so as to be 180 degrees apart as the eccentric crankshaft rotates.

When dispensing beverages it is of advantage to know the delivery pressure at the pump output as this enables the rate of flow to be more accurately defined, thus enabling the quality of the dispensed beverage to be improved. Presently used pumps provide an increase in pressure from the inlet to outlet and some pumps are provided with spring loaded pressure by-pass valves enabling the inlet to outlet pressure differential to be adjusted. Such an arrangement is satisfactory as long as the inlet pressure remains constant but varying inlet pressures will cause changes 105 in the output pressure and hence flow rate. With beverages such as beer and according to kind, the inlet or keg pressure maybe variable from 0 to 30 p.s.i., (0 to 200 KPa).

It is an object of this invention to provide an improved pump which enables the beverage dispense pressure to be maintained substantially constant and without excessive pressure occurring but which is of a simple con- struction preferably with a by-pass valve device incorporated within the pump casing as an integral part thereof.

According to this invention, there is provided a helix pump primarily for dispensing beverages and having an eccentrically mounted rotor provided within a casing forming the pump chamber and with the pump fluid inlet and outlet ports located adjacently in the casing through respective passageways, characterised by a valve means comprising a diaphragm urged by a spring means to close further passageways communicating with the inlet and outlet respectively whereby the sum of the pressures at the inlet and outlet and acting on the diaphragm, when sufficient, causes the diaphragm to lift thereby establishing communication between the inlet and outlet ports to by-pass the pump chamber.

By this means a pressure by-pass is pro- vided between the inlet and outlet of the pump and advantageously located at a junction or dividing partition between the inlet and outlet ports. The pump is preferably so de-_ signed that the said ports and further passage- ways are adjacent and separated by the diaphragm which may comprise a rubber by-pass valve which is normally urged by a spring means to close across a barrier between the two further passageways. The opposite side of the diaphragm valve is at atmospheric pressure and spring loading thereon may be adjustable to maintain the valve closed according to required lift- off pressure.

In such an arrangement the inlet and outlet pressures within the pump act in combination to lift the by-pass valve against the opposing spring pressure force and atmospheric pressure together. By this means the valve included within the pump therefore substracts inlet pressure from the pressure developed by the pump, the resultant being the outlet pressure which is completely independent of inlet pressure. An increase in the inlet pressure will tend to partially open or lift the diaphragm valve thus reducing the load on the pump and the driving motor. The invention makes use of the input pressure in such a way that the power consumption of the pump is reduced and excessive beverage dispense pressure avoided.

The invention is described in more detail in conjunction with the accompanying drawing showing one embodiment of a pump according to the invention. The drawing shows a longitudinal section through the pump and valve means.

Referring to the drawing, a casing comprising a moulding or casting 1 includes connection ports for the inlet 2 being a flow line from the cask or the like containing the beverage and outlet 3 feeding the dispense point tap. The pump has internal ports 4 and 5 being an. inlet and outlet passageway respectively for the pump chamber 6 defined by the annular casing wall 7a. The ports 4 and 5 are delimited by means of a baffle or partition 7. Within the pump chamber 6 formed by the casin wall 1 a is provided an eccentric rotor 7 having a central orifice 8 engaged by a crank pin 9 mounted on a shaft 9a coupled with a suitable motor drive and rotatable about the casing centre axis 10. The rotor is engaged by the partition 7 at a slotted portion 11 whereby it is constrained against rotation but nevertheless oscillates around the casing centre axis 10 whereby the point of contact between the rotor 7 and the inner wall 1 a of the pump casing 6 moves peripherally and in an anti-clockwise direction as shown by arrow A in the drawing. This construction is a kind 2 GB 2 130 302A 2 of 'helix' pump so-called. The inlet and outlet ports 4 and 5 to the pump chamber are also enabled to communicate through further passageways 12 and 13 which are delimited by the partition 7 and closed by a rubber diaphragm valve 14. The valve 14 is urged into engagement with the seatings provided on the casing and the partition 7 by spring 15 but may be lifted by pessure which will be a combination of pressure acting from the inlet and from the outlet via passageways 12 and 13. When the valve is lifted through combination of pressures direct communication between the inlet and outlet is provided.

The particular embodiment described provides a pump of relatively simple construction with few moving parts and in which the pressure by-pass valve is provided in a manner not interfering with the normal operation of the pump and in a way which provides a robust and reliable construction. The pressure at which the diaphragm 14 lifts may be adjusted by a suitable screw threaded slug 16 permitting variable pre- compression to be applied to the springs 15. The periphery of the diaphragm 14 is retained by a collar 17 and screw slug 18. Both the slugs 16 and 18 engage an internal threading 19 provided in a tubular integral extension housing 20. In the arrangement the central area of diaphragm 14 deflects upwardly to allow communication between passageways 12 and 13.

Claims

1. A pump having an eccentrically mounted rotor provided within a casing form ing the pump chamber and with the pump fluid inlet and outlet ports located adjacently in the casing and communicating with the interior of the casing through respective passageways, characterised by a valve means comprising a diaphragm urged by a spring means to close further passageways communicating with the inlet and outlet respectively whereby the sum of the pressures at the inlet and outlet and acting on the diaphragm, when sufficient, causes the diaphragm to lift thereby establishing communication between the inlet and outlet ports to by-pass the pump cham- ber.

2. A pump in accordance with claim 1, wherein the inlet and outlet ports are located at a junction or dividing partitions between the inlet and outlets of the pump.

3. A pump in accordance with claims 1 or 2, wherein the ports and further passageways are adjacent and separated by the diaphragm which comprises a flexible by-pass valve nor mally urged by spring means to close across a partition barrier between the two further passageways.

4. A pump in accordance with claim 3, wherein the side of the valve diaphragm opposed to the passageways is subject to atmo- spheric pressure.

5. A pump in accordance with claims 2, 3 or 4, wherein the dividing partition engages the rotor to prevent rotational motion.

6. A pump substantially as herein de70 scribed and as shown in the drawings.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd.-1 984. Published at The Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.

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