GB2050513A - Rotary Positive-displacement Fluid-machines - Google Patents

Abstract

In a fuel-supply unit comprising a roller-vane pump 1 driven by an electric motor 2, a chamber for the pump rotor 19 and vanes 25 has at at least one end thereof a fixed plate 29, 30 comprising at at least the surface next the rotor and vanes a wear- resistant material e.g. aluminium oxide. The remainder of the plate may be made of a malleable aluminium alloy. <IMAGE>

Description

SPECIFICATION Fuel Supply Unit The present invention ralates to a fuel supply unit.

Fuel pumps are known in many forms; they usually consist of a pump component and of a motor component, namely an electric motor driving the pump component, an aligned assembly of pump and electric motor, for example in a common housing, being preferred. In this case the rotating component of the particular pump used, for example a regeneration pump (side channel pump) or roller cell pump, can be mounted on the axle or shaft which also serves for mounting the armature of the electric motor.

Rotational drive is then frequently carried out by means of an entraining device driven by the electric motor and, for example, integrally connected thereto, the entraining device engaging in an opening in the pump rotary component.

In the case of a roller cell pump-although combinations of roller cell pumps and regenerative pumps can also be used in appropriate succession-the pump rotating component (slotted disc), which has slots containing the pump bodies (usually formed as rollers) is journalled between two plates arranged one on either side of the component, one of the plates being termed the base plate and the other the support plate. The track for the rollers is then formed by an internal bore of an intermediate plate, which surrounds the slotted disc in an eccentric relationship necessary for the operation of the ump.

Thus, sliding surfaces of large area exist between the pump rotor, that is the slotted disc, which sometimes rotates at a considerable speed, and the stationary plates bearing against the pump rotor on each side, that is the base plate and support plate.

Usually, these sliding surfaces are made as wear-resistant as possible. This can be done when the pump parts are made from a suitable aluminium alloy, for example in the form of aluminium die-cast alloys, by applying to those surfaces that are subjected to sliding wear an aluminium oxide coating, which increases the wear resistance. However, a drawback is that these wear-resistant aluminium oxide coatings, formed for example by eloxadizing, are comparatively thin, so that the wear resistance is not optimum.

According to the present invention there is provided a fuel supply unit comprising an electric motor and a fuel pump, which is drivable by the motor and which comprises an annular member defining, at its inner circumference, the periphery of a substantially cylindrical pump chamber, a pair of end members disposed one at each end of the annular member, at least one insert plate, which is disposed between the annular member and a respective one of the end members to define an end surface of the annular chamber and which comprises a wear-resistant material at least at that surface, and an impeller comprising a rotor disposed in the chamber eccentrically of the axis thereof and a plurality of rollers, which are guided in slots in the rotor and which are on rotation of the rotor urged by centrifugal force against the periphery of the chamber to each define a pump working space ahead of the respective roller in the direction of rotation of the rotor.

A fuel supply unit embodying the invention may possess the advantage that, in the contact region between the pump rotor and the adjacent surfaces, a relatively high wear resistance can be obtained, since as only a small amount of material may be required, a high-quality sliding material (wearing material) can be employed for forming the or each insert or sliding surface plate. By contrast, either or each supporting end member, for example a base plate and/or support plate, can be made from inexpensive alloys.

As a consequence of the use of high-quality sliding materials for the or each insert plate disposed against the supporting components and clamped together with them, oxide coating of existing forms of pump components is rendered unnecessary. In addition, where plates of socalled malleable aluminium alloys are used, excellect and very thick aluminium oxide coatings can be obtained, by contrast to cast alloys which are difficult to coat.

It is furthermore advantageous that such insert plates are replaceable and do not have any effect on the axial clearances of the pump.

Finaliy, it is of especial advantage that where a change occurs in the position of the slots or openings for the suction chamber or delivery chamber of a thus-formed roller cell pump, account can be taken of these changes largely by simple modifications to the punching or stamping tools for the thin insert plates. Accordingly, highly expensive changes to die-casting moulds are usually no longer required.

Preferably, to facilitate installation of the or each insert plate in conjunction with the end members, for example base plate, intermediate plate and support plate, of the fuel pump, lugs, humps tongues or similar projections, bent over or sheared off at the edge region of the insert plate, are provided to serve as fixing aids.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: Fig. 1 is a sectional elevation of an electric fuel pump for installation in a fuel tank, Figs. 2a and 2b are elevational and sectional views of an insert plate associated with a base plate of the pump of Fig. 1, and Figs. 3a and 3b are elevational and sectional views of an insert plate associated with a support plate of the pump of Fig. 1.

Referring now to the drawings, Fig. 1 shows a fuel supply unit suitable for supplying fuel and consisting of a pump and electric motor, the construction of which will be briefly described first of all to assist understanding.

A fuel supply pump 1-in the illustrated example a roller cell pumps and an electric motor 2 are combined to form a fuel supply unit, the electric motor 2 and an intermediate flange 3, which forms a support or cover plate for the pump, being housed in a pot-shaped housing 4, the intermediate flange 3 being only partially in the housing. The housing 4 is closed by a cover 5, on which a pressure pipe connection (not shown) is disposed. Between the housing 4 and the cover 5 there is a seal 6, and the cover is secured to the housing by a rim or flange 7.

In Fig. 1, from left to right- that is from the delivery to the suction side-there are arranged first the pump 1 and then the electric motor 2 whereby in the present embodiment of an electric fuel pump suitable for open tank installation, the pump 1 is mounted overhung on the intermediate flange 3 with its suction region 8a, 8b accessible from both sides. The fuel supplied by the pump under pressure flows, as will be explained later, through the electric motor to cool the latter.

The electric motor 2 consists of an armature 9 and a magnetic element 10. The armature 9 is journalled, in order to permit rotation, by bearing bushings 11 a and 11 h on a stationary shaft 12.

The bearing bushings 1 lea and 1 1b are disposed inside a support tube 32, which is rotatably mounted on the axle 12 and carries a laminated core 13, an armature winding assembly 14 and a commutator bushing 1 5. The attaching of these components to the armature tube is carried out by pressing or by using plastic filler components, which when injected around the individual elements, ensure a good, rotationally fast and axially firm connection. A further bushing, or sleeve 1 6 firmly connected in some other manner to the armature components, is situated at the side adjacent to the pump 1 and has at least one driving pin 17 which engages, to provide a rotational coupling, in a corresponding recess 1 8 in the pump 19.

Carbon brushes 20a and 20b, mounted in cages, slide on the commutator bushing 1 5.

The magnetic element 10 of the electric motor 2 consists of a permanent magnet, which is mounted in a tubular sheet 21 made of magnetically conductive material.

The pump 1 comprises an outer base plate 22, which is connected by connecting elements, to be mentioned later on, with the intermediate flange 3 and thus with the housing 4 and which has a central bore 22a receiving the axle 12, the axle being pressed into place.

Axially adjacent to the base plate 22 is an intermediate plate 23 of the roller cell pump, which is adjoined by the already-mentioned intermediate flange 3; the flange 3 forms a support plate 28 on the side of the intermediate plate 23 remote from the base plate 22. In Fig. 1 it can be seen that the base plate 22 and intermediate plate 23 are clamped together by bolts 24a and 24b, for example as one preassembled unit, and this unit can be connected and clamped to the intermediate flange 3 by further bolts (not illustrated) staggered around the circumference relative to the bolts 24a and 24b.

The base plate 22, intermediate plate 23 and support plate 28 region of the intermediate flange 3 house between them a pump rotor 19, which has slots 1 9a containing rollers 25 serving as pump bodies.

As already mentioned, in the present embodiment the pump is suitable for tank installation, and therefore the suction region of the pump is freely accessible for fuel to be supplied via the suction region 8a in the base plate, and also the region 8b on the opposite side as a consequence of the inward stepping down of the intermediate flange 3. The delivery side of the pump, which is formed by a radially inner pressure chamber 26, is connected to a chamber 27 which forms part of the electric motor region.

The connections of the pump 1 to the fuel in the tank via the suction chamber and to the electric motor chamber surrounded by the housing 4 are thus channels that are open except for being controlled by the pump rotor.

In the illustrated embodiment of a roller cell pump, the rollers 25 are pressed by centrifugal force against the track formed by the internal bore of the intermediate plate 23. As a consequence of the eccentric position of the intermediate plate 23 with respect to the revolving rotor 1 9 and rollers 25, there is provided a crescent-shaped pump working chamber which decreases in size with respect to a particular roller 25 during rotation of the rotor, so that the fuel situated in this chamber is pressurized and then discharged via the chamber or opening 26.

In the rotational movement, the rollers 25 slide not only along the internal track of the intermediate disc 23-where substantially rolling contact takes place since the rollers 25 run on this internal track-but they also slide along the mutually facing sliding surfaces in the regions of the base plate 22 and support plate 28 of the intermediate flange 3.

These surfaces constitute a kind of roller cage retaining the rollers on both sides and are provided with a high-quality sliding materials with a very high wear resistance. This is achieved by providing stamped plates 29 and 30 of the aforementioned high-quality sliding material to act as tracks on the plates on both sides of the rotor, namely the base plate 22 and support plate 28 of the intermediate flange 3.

In Figs. 2a, 26 and 3a, 3b, these pump components, which may be termed sliding surface plates, are illustrated in more detail. It can be seen that these plates 29 and 30 are provided with the same apertures, for example suction grooves 8a, external delivery groove 31, and internal pressure chamber 32, as the associated support plates (base plate 22 and support plate 28) and as are necessary for the functioning of the roller cell pump. In Figs. 2a and 2b the plate 29 for the box plate 22 is illustrated; this possesses, in addition to the suction groove 8a, four apertures 33 distributed around its periphery, these apertures serving for securing the base plate, plate 29, intermediate plate 23 and, at least in regard to two of these apertures, the adjoining plate 30 and the support plate 28 of the intermediate flange 3.

Thus, for assembly, the plate 29 according to Figs. 2a and 2b can be fixed and secured by two bolts to the base plate 22, the intermediate plate 23 also being fixed-with radial gap adjustment-by these two bolts 24a and 24b.

The same applies for the plate 30 associated with the intermediate flange 3, in particular the support plate 28 formed by the flange. The plate 30 can also be initially fixed to the intermediate flange by suitable means and then, together with the intermediate flange, be fixed and secured by screws to the unit comprising base plate and intermediate plate.

From the sectional views of Figs. 2b and 3b, the small thickness of the two plates 29 and 30 can be seen, as compared with their radii.

In an advantageous embodiment, the plates 29 and 30 can possess, as an assembly aid, lugs, tongues or fixing noses 29a and 30a bent over at the edge regions of the plate to extend axially of the pump, the lugs serving for initial attachment of the plates to the associated support components. It will be understood that the support components, i.e., the base plate 22 and the support plate 28 of the intermediate flange 3, have suitable apertures into which the lugs 29a and 30a can engage.

The plates 29 and 30 consist of a suitable high-quality sliding material or can be simply and inexpensively provided with highiy wear-resistant external surfaces or coatings. If the plates are made of malleable aluminium alloys, very good and thick aluminium oxide coatings can be provided to increase the wear resistance, as compared with cast alloys which are usually difficult to provide with oxide coatings.

Claims (6)

Claims

1. A fuel supply unit comprising an electric motor and a fuel pump, which is drivable by the motor and which comprises an annular member defining, at its inner circumference, the periphery of a substantially cylindrical pump chamber, a pair of end members disposed one at each end of the annular member, at least one insert plate, which is disposed between the annular member and a respective one of the end members to define an end surface of the annular chamber and which comprises a wear-resistant material at least at that surface, and an impeller comprising a rotor disposed in the chamber eccentrically of the axis thereof and a plurality of rollers, which are guided in slots in the rotor and which are on rotation of the rotor urged by centrifugal force against the periphery of the chamber to each define a pump working space ahead of the respective roller in the direction of rotation of the rotor.

2. A fuel supply unit as claimed in claim 1, wherein the or each plate forms a guide track for the ends of the rollers at the respective end of the chamber and is clamped to the respectively adjacent one of the end members.

3. A fuel supply unit as claimed in either claim 1 or claim 2, wherein the or each plate is formed by stamping and is provided with apertures for passage of fuel therethrough and fastening means.

4. A fuel supply unit as claimed in any one of the preceding claims, wherein the or each plate is provided at its edge region with at least one projection projecting out of the plane of the plate, and the respectively adjacent one of the end members is provided with a corresponding aperture or corresponding apertures receiving the projection or projections.

5. A fuel supply unit as claimed in any one of the preceding claims, wherein the or each plate comprises aluminium alloy and the wear-resistant material is provided by a coating of aluminium oxide.

6. A fuel supply unit substantially as hereinbefore described with reference to the accompanying drawings.