GB2027810A - Rotary pumps - Google Patents

Abstract

In a fuel feed pump assembly the armature (5) of an electric motor (3) has a rotary hollow shaft (4) on a fixed axle (14) and a driver member (19) with a projection(s) (20), which engages with a pocket(s) (28) in an intermediate driver member (25) for a rotary member (23) of a fuel pump e.g. a roller- vane pump, (2), the driver member (25) having a projection(s) (26) that engage with a recess(es) (27) in the rotary member (23). The intermediate driver member (25) has sufficient axial and radial clearance relative to the shaft (4) and the axle (14) to obviate jamming due to swelling of parts caused by the fuel. <IMAGE>

Description

SPECIFICATION Fuel feed pump The invention relates to a fuel feed pump, and particularly to a fuel feed pump assembly for a motor vehicle which comprises a single or multi-stage pump system and an electric motor driving the pump system arranged in a common housing.

Fuel feed pumps are already known in which the fuel pump system and the electric motor are accommodated in a common, cupshaped housing and in which the fuel pump system can be of two-stage construction comprising a preliminary stage and a main stage.

The rotary drive of the rotating pump member is effected by the armature of the electric motor by means of a driver lug which engages a recess in the vicinity of the region of the bearing of the drive rotary member of the pump. It has been found that, as a result of certain qualities of the petroi, and particularly as a result of the alcohols (such as methanol) container therein, specific components, such as plastics members of electric fuel pumps, can swell up after long periods of operation, so that it is possible that the pump might jam and run sluggishly or even fail. This kind of jamming results chiefly from a swelling in the axial direction of the pump.

An object of the invention is to provide a pump assembly in which the disadvantages of the prior art are overcome by providing free spaces to accommodate any swelling of the parts.

In accordance with the invention there is provided a fuel feed pump assembly comprising a single or a multi-stage pump and an electric motor in driving connection with the pump arranged in a common housing in which assembly the armature of the motor includes a hollow shaft supported for rotation on a stationary axle and has a first driver member fixed with respect to the armature, axial movement of the armature along the axle being prevented or limited by abutment means provided on said axle; the driving connection between the electric motor and the pump includes an intermediate or second driver member freely mounted with radial clearance on said stationary axle and having clearance in the axial direction between said motor and said pump; and the intermediate driver member is in drive-transmitting connection with the first driver member and is in drive-transmitting connection with a rotary member of the pump by one or more projections provided on said intermediate driver member and or said rotary member.

Thus, in contrast to the prior art, the fuel feed pump assembly in accordance with the invention has the advantage that possible swelling of the components is rendered harmless by the interposed driver member acting as a clutch, since a large amount of free space for swelling is available. Furthermore, the metal support of the armture in the form of the so-called hollow shaft armature prevents the force of the armature from acting upon the grooved disc, this metal axial support also rendering it impossible for the armature to jam as a result of the swelling of components of the armature.

A further advantage is that it is a simple matter to vary the overall size of the pump in an axial direction by virtue of the interchangeability of the intermediate clutches intermediate driver parts; also, there is the possibility of using a grooved disc having a wear-resistant carbon brush acting as a bearing.

In additon to providing a swell-resistant intermediate driver member, it is also particularly advantageous to construct further components of the fuel feed pump in a swellresistant form, particularly to construct the locking bolts, provided in the valve devices, at least partially from a methanol-resistant plastics material such as Viton or from a metal and Viton connecting part in order to obtain high strength at the spring seat and satisfactory sealing of the valve by the Viton dome.

Embodiments of the invention are hereinafter described, by way of example, with reference to the accompanying drawing which is a sectional elevational view of a fuel feed pump unit constructed according to the invention.

The basic construction of a fuel feed pump unit for a motor vehicle, in which the single-or multi-stage pump system and the electric motor driving the rotary parts of the pump system are arranged in a common, cup-shaped housing, is known, so that these basic features will only be discussed briefly. The fuel pump region is designated 1 in the drawing and comprises a roller vane pump 2 and is of single-stage construction. The electric motor 3 includes the actual armature 5 mounted on a hollow shaft 4, and the two permanent magnets 7aand 7bmounted within a magnet holding tube 6. The common housing of the pump 2 and motor 3 is denoted by reference numeral 31.Current is fed to the winding 5A of the armature 5 by way of a commutator 8 on which slide commutator brushes mounted in cages 9aand 9b. The cages 9aand 9bfor the commutator brushes are mounted on a brush holder 10 comprising a substantially circular plate. The end cover region 11 of the pump unit is located adjacent to the brush holder 10 and includes a stationary bearing 1 2 for supporting one end of a continuous, stationary axle 14 which is mounted at the other end in the petrol intake region by a bearing 1 3. The bearing 1 3 for the axle 14 in the intake region is formed by the base plate 2A of the roller vane pump 2 which is arranged at this location.The axle 1 4 is pressfitted in a central bore in the base plate 2A.

It is of importance that, in order to avoid any jamming in the region of the armature 5, the armature 5 includes an injection-moulded member 1 5 which, as shown, is mounted on and secured to the hollow shaft 4 and on which and in which is mounted thhe armature winding 5A made from so-called baked lacquer insulated wire, thus also dispensing with the otherwise expensive impregnation of the winding. The hollow shaft 4 carrying the armature 5 is journalled at both ends on the axle 14 by so-called DU bearing brushes 15a and 1 sub which have advantages with respect to wear and operational reliability particularly in the case of fuels having low-boiling point constituents.The armature 5 is axially located by retaining rings 17a, 17bwhich are seated in grooves 16a and 166 in the axle 14 on both sides of the bearing bushes 15a and 1 sub and which fix the hollow shaft 4 of the armature and the bearing bushes with a specifically adjusted amount of clearance in the axial direction, optionally, by the intermediary of interposed washers 1 8.

A driver 1 9 which is associated with the armature and which is driven thereby, can either be an integral part of the injection moulding 1 5 of the armature and have one or a pluraity of driver lugs 20 projecting axially towards the pump 2, or it can be a separate member of plastics material, that is to say, a separate driver which is inserted into the injection moulding 1 5 of the armature 5. In this case, the armature driver 1 9 is separated from the injection moulding 1 5 of the armature approximately along the broken line 21 and it is fixedly seated on the injection moulding 1 5 by means of an annular projection 22, and it is also fixedly seated on the shaft 4.

All the axial forces, such as armature pull, gravity, or accelerative forces, exerted by the armature on the grooved disc 23 of the roller vane pump 2, are avoided by the axial support of the armature.

An intermediate driver member 25 serves to connect the armature 5 to the groove disc 23.

In a different type of pump the disc 23 would be replaced by another rotary part of the pump, such as the impeller in the case of a side channel pump, and this other rotary member would be rotated by the driver member 25. The intermediate driver member 25 is in the form of a one-piece driver member made preferably from plastics material and has pins or driver lugs 26 at one end for engaging recesses 27 in the grooved disc 23, and pockets 28 at the other end for the teeth, projections or driver lugs 20 of the armature driver 1 9. The intermediate driver member 25 has a large amount of clearance relative to the axle 14 and to the armature driver 19, so that any effects of swelling are not detrimental.

The driver member 25 is guided in the longitudinai diirection relative to the grooved disc 23, and thus to the axle 14, by means of the pins 26, wherein any longitudinal play can be limited by an integral collar which is not illustrated.

It willl be appreciated that, with respect to its driver function, the driver member 25 can be of alternative constructions, for example, it can have pins or teeth at both ends which engage complementary recesses in the grooved disc 23 and in the armature driver 1 9. It is only essential that a rotary drive is effected by virtue of mutual engagement of projections on both ends of the intermediate member 25, this engagement of the projections being positive in the rotational direction but not being frictional at least with respect to the armature driver 1 9 and the driver member 25.

By virtue of the interposed member 25, the overall size of the pump, namely the width of the intermediate plate 29 completing the construction of the roller vane pump 2, the width of the grooved disc 23 and of the rollers mounted therein and, if required, also the width of the support plate 30 arranged at the end, can be varied, and only the length of the driver member 25 also needs to be changed.

It is also an advantage that a grooved disc 23 having a wear-resistant carbon bush acting as a bearing on the axle 14 can be used by appropriate adaptation of the intermediate member 25, thus resulting in a higher driving moment of the elongate driver pins 26 of the intermediate member 25, in addition to a smaller amount of wear. An essential feature is that the entire driver connection is designed such that adequate space for the swelling of individual driver parts exists on all sides.

Claims (10)

1. A fuel feed pump assembly comprising a single or a multi-stage pump and an electric motor in driving connection with the pump arranged in a common housing in which assembly the armature of the motor includes a hollow shaft supported for rotation on a stationary axle and has a first driver member fixed with respect to the armature, axial movement of the armature along the axle being prevented or limited by abutment means provided on said axle; the driving connection between the electric motor and the pump includes an intermediate or second driver member freely mounted with radial clearance on said stationary axle and having clearance in the axial direction between said motor and said pump; and the intermediate driver member is in drive-transmitting connection with the first driver member and is in drive-transmitting connection with a rotary member of the pump by one or more projections provided on said intermediate driver member and/or said rotary member.

2. A pump assembly as claimed in claim 1, in which said pump is a roller vane pump and said rotary member is a grooved disc.

3. A pump assembly as claimed in claim 2, in which the intermediate driver member has at least one driver pin which is directed axially towards and is in drive-transmitting connection with, the grooved disc of the roller vane pump, and which at the same time fixes the intermediate driver member relative to the grooved disc and with clearance relative to the stationary axle.

4. A pump assembly as claimed in claim 3, in which said intermediate driver member has a plurality of said driver pins.

5. A pump assembly as claimed in any one of claims 2 to 4, in which the intermediate driver member is disposed closely adjacent to the grooved disc.

6. A pump assembly as claimed in any one of the preceding claims, in which that side of the intermediate driver member directed towards the electric motor has reception pockets which are engaged by dogs or driver lugs of said first driver member which is rigidly connected to the armature.

7. A pump assembly as claimed in any one of claim 2 to 6, in which the grooved disc is mounted on the stationary axle by means of a carbon bush.

8. A pump assembly as claimed in any one of the preceding claims, in which the stationary axle has retaining grooves which are arranged one at each end of the armature/commutator assembly of the electric motor and which are engaged by retaining rings constituting said abutment means, and said hollow shaft is mounted on the stationary axle by means of bushes and abuts said retaining rings.

9. A pump assembly as claimed in claim 8, in which washers are interposed between said retaining rings and said hollow shaft.

10. A fuel feed pump assembly substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.