GB2120728A

GB2120728A - Rotary fluid meter or pump

Info

Publication number: GB2120728A
Application number: GB08212537A
Authority: GB
Inventors: Alan Leonard Beresford
Original assignee: DAVALL MOULDED GEARS
Current assignee: DAVALL MOULDED GEARS
Priority date: 1982-04-29
Filing date: 1982-04-29
Publication date: 1983-12-07

Abstract

A meter (1) for eg. water, has at least one member such as a pair of meshing oval gears (8, 9), which is (are) rotatable within a chamber (5) defined at least partially by an inner surface (15) of a housing (2). A preformed insert (14) made of eg. a plastics, metallic, or ceramic material, is located between the inner housing surface (15) and the or each rotatable member in sealing contact with the latter. The preformed insert is particularly useful when the inner housing surface (15) is tapered with respect to the rotational axis (10, 11) of the or each member (8, 9) to facilitate moulding of the housing. The machine may be a pump instead of a meter. <IMAGE>

Description

SPECIFICATION Pump or meter sealing This invention relates to the sealing of pumps or meters and is especially, but not exclusively, related to the sealing of pumps or meters having moulded housings.

In known pumps or meters having at least one rotatable member for performing the pumping or metering function, it has been found that the inner housing surface, with which the rotatable member engages in sealing contact, tends to be insufficiently smooth and/or regular, thereby reducing the continuous sealing engagement between this surface and the rotatable member and, hence, the efficiency of the pump or accuracy of the meter, as the case may be.

An additional disadvantage associated with pumps or meters of this type and particularly those having moulded housings, is that at least the inner housing surfaces have to be tapered, although only slightly in some cases, to enable the housing to be removed from the mould. However, even a slight taper of these inner working surfaces will reduce the necessary sealing engagement with the rotatable, pumping or metering member.

It is an object of the invention to overcome the disadvantages associated with the known type of pumps or meters described above.

Accordingly, the invention provides a pump or meter of the type described above, including a preformed insert located between an inner surface of the pump or meter housing and an associated pumping or metering member rotatably mounted therewithin.

The preformed insert may be made of any suitable material, such as, a plastics, metallic or ceramic material, as long as its working surface, namely, that engaged in sealing contact with the rotatable member, is sufficiently smooth and/or regular to provide such contact. Clearly, it is easier to form the preformed insert with the necessarily smooth and/or regular surface than it is to form the inner housing with such a surface. Also, if the housing is moulded, say, from a plastics material, with otherwise tapered inner working surfaces, then the preformed insert may be provided, at its non-working surface, with a corresponding taper, such that its working surface is non-tapered when it is fitted within the pump or meter.

A preferred embodiment of water meter in accordance with the invention will now be described by way of example and with reference to the accompanying drawings in which Figure 1 is a plan view in partial section of the meter and Figure 2 is a section along the line ll-ll of Fig. 1.

Referring to the drawings, a water meter 1 comprises a moulded housing of two parts 2, 2' which are joined together to define a metering chamber 5 and respective inlet and outlet ports 3, 4, with end closure plates 6, 7.

A pair of generally elliptical or oval metering members 8, 9 are rotatably mounted within the chamber 5 upon respective parallel axes 10, 11. The major axes of the generally elliptical or oval members 8, 9 are normal to each other, such that there is always peripheral contact between the two members during rotation. Due to the elliptical or oval shape of the two members 8, 9, the region of peripheral contact therebetween oscillates about a line A which is generally axial with respect to the inlet and outlet ports 3, 4.

The peripheries of the metering members 8, 9 are provided with flexible, projecting teeth or fins, as shown at 12, which intermesh at the peripheral contact region and which engage the inner working surfaces 1 3 of respective preformed inserts 14. As the two metering members 8, 9 are rotated by the flow of water through the meter 1, via the inlet and outlet ports 3, 5 this engagement between the flexible fins or teeth 1 2 and the inner working surface 1 3 of the respective inserts 14 occurs in both a sealing and sweeping manner.

When the two halves 2, 2' of the housing are moulded, it does not matter if their inner surfaces 1 5 are particularly smooth and/or regular, because the preformed insert 14, which is fitted into the meter 1 on assembly of the two housing halves 2, 2', is made with an accurately smooth and/or regular inner working surface 1 3 which provides the necessary sealing engagement with the flexible fins or teeth 1 2 of the associated member 8, 9.

Lip-seals, such as those at 1 6 and 17, are provided to seal the preformed inserts 14 within the housing.

Also, the preformed inserts 14 eliminate any irregularities on inner surfaces of the housing which might otherwise have to act as the working surfaces for the chamber 5. For instance, the irregularity formed between the joint 18 between the two housing halves 2, 2' is covered by the inserts 14, as shown in Fig. 2.

Furthermore, if the two halves 2, 2' of the housing have, say, tapered inner surfaces 15, whereby removal of each half from its mould is facilitated, then the non-working, outer surface of each preformed insert 14 can be correspondingly shaped, such that the inner working surface 1 3 of each insert eliminates such an undesirable taper, whereby efficient sealing engagement between the fins or teeth 1 2 and the surface 1 3 is maintained.

An added advantage of this form of preformed insert 14 is that it can be readily replaced, should wear of the inner working surface 1 3 occur.

At least one of the metering members 8, 9 is connected to means for indicating the vol ume of water flowing through the meter 1.

Additionally, each preformed insert 14 may be made of any suitable material, for instance, a plastics, metallic or ceramic material, al though in the embodiment described above, a plastics material is preferred.

The housing, whether it be made in two halves, as described above, or in any other number of parts, can be moulded, diecast or pressed from any suitable material.

Claims

1. A pump or meter comprising a housing and at least one member which is rotatable within a pumping or metering chamber de fined at least partially by an inner surface of the housing, wherein a preformed insert is located between the inner housing surface and the rotatable member, whereby, in use of the pump or meter, the rotatable member engages in sealing contact with the inner, working surface of the preformed insert.

2. A pump or meter according to claim 1, wherein the preformed insert is of a plastics, metallic or ceramic material.

3. A pump or meter according to claim 1 or 2 whose inner housing surface is tapered with respect to the rotational axis of the member, wherein the other, non-working sur face of the preformed insert has a correspond ing opposite taper to that of the inner housing surface, whereby the inner, working surface of the preformed insert is substantially parallel to the rotational axis of the member.

4. A pump or meter according to claim 1, 2 or 3 comprising a pair of rotatable, gener ally elliptical or oval members which are rota tably mounted within the pumping or meter -ing chamber upon respective, parallel rota tional axes and whose major axes are normal to each other, thus providing continuous per ipheral contact between the two members during their rotation in use of the pump or meter.

5. A pump or meter according to claim 4, wherein the peripheries of the rotatable mem bers have flexible, projecting teeth or fins which intermesh at the peripheral contact re gion of the two members and which sealingly engage with the inner, working surfaces of respective preformed inserts.

6. A pump or meter according to any preceding claim, wherein the or each pre formed insert is sealed within the pumping or metering chamber of the housing by means of lip seals or '0' seals.

7. A pump or meter according to any preceding claim which is moulded from a plastics material in two halves, the preformed insert being made of a plastics material.

8. A water meter substantially as herein before described with reference to the accom panying drawings.