GB1594873A

GB1594873A - Fuel feed unit

Info

Publication number: GB1594873A
Application number: GB1152/78A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-01-13
Filing date: 1978-01-12
Publication date: 1981-08-05
Also published as: DE2701161A1; JPS5390006A

Description

(54) FUEL FEED UNIT (71) We, ROBERT BOSCH GmbH, a German Company, of Postfach 50, 7 Stuttgart 1, the Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to fuel feed units.

Carrier plate assemblies in known fuel feed units are not always sufficiently precise in the guidance of the carbon brushes which engage the commutator of the electric driving motor of the pump used so that malfunctions can occur, particularly during rough running. A further problem has been that the carbon guides used hitherto have not been attached sufficiently precisely on the supporting carrier plate, which has been made of a suitable plastics or other mouldable material, so that under the effect of the fuel and, in certain circumstances, when changes in the material occur as a result of a loosening of the guide or a fault, malfunctions can occur.

In accordance with the present invention there is provided a fuel feed unit comprising a roller cell pump and an electric motor for driving the pump, the pump and motor being enclosed in a housing, and the motor having carbon brushes received in brush guides constructed as tubular holders which are circumferentially closed and which are secured to a carrier plate by one-piece retaining claws extending through the carrier plate.

The invention is described further hereinafter, by way of example, with reference to the accompanying drawings, in which: Fig. I is a longitudinal section through a fuel feed pump in accordance with the invention; Fig. 2a is a section on the line li-Il in Fig.

1; Fig. 2b is an end view of the parts shown in Fig. 2a; Fig. 2c is a cut-out detailed view illustrating the manner of attaching the carbon brush guide; Figs. 3a and 3b show a further embodiment of the present invention, Fig. 3a being a section corresponding to the line 11-Il in Fig. 1 and Fig. 3b being an end view; and Fig. 4 is an enlarged detail view illustrating a preferred manner of attaching an electrical connection lead to a retaining element of the brush carrier plate.

The fuel feed pump shown in Fig. 1 comprises two main elements, disposed one behind the other in an axial direction, which are enclosed by a common housing 1, the two main elements comprising a roller cell pump 3 disposed in the region of a fuel inlet 2, and an electric motor 4 for driving a shaft 5 which extends forwardly to the roller cell pump 3 and drives, by way of driver wedge 6 extending at right-angles to the shaft 5, a moving element of the roller cell pump 3.

The outlet of the fuel feed pump is indicated by the reference numeral 7. Fuel flows through the region of the housing occupied by the electric motor and exits at the outlet 7 through a non-return valve 8. The shaft 5 is journalled in the housing at locations 9a and 9b.

As the roller cell pump and electric motor which have been selected for illustration in the present embodiment are not the principal subject-matter of the present invention, they consequently do not require any detailed explanation. The most important part of the present construction is the region of the brush carrier plate, which is designated 10 in Fig. I. The brush carrier plate supports carbon brushes which abut a commutator 11 of the electric motor, the carbon brushes not being visible in the sectional drawing of Fig.

1. The sectional drawing of Fig. 2a, however, shows the two carbon brushes 12a and 12b, which lie opposite each other and are supported by the brush carrier plate 10. The brush carrier plate 10 is itself mounted in the housing 1 on projections 13 and 14, the carrier plate having a central opening 15 to accommodate the commutator and the shaft 5.

The carbon brushes are located in respective holders 16a and 16b, the brushes being slidably displaceable in the holders in a direction radially of the commutator under the pressure of springs 17a and 17b.

The carbon brush guides comprise sheet metal parts 18a and 18b each of which is closed on all lateral sides, is open at its forward and rearward ends in the direction of the displacement of the associated carbon brushes 12a and 12b, and forms a holder, each part 18a, 18b being secured on the carrier plate 10 by means of respective retaining claws 19. The carrier plate can be made of any mouldable material. The retaining claws 19 are, as shown in Fig. 2b in the case of the brush guide 16b, disposed on the base wall 20 of the brush guide, as viewed from the forward or the rearward end in the direction in which the carbon brushes slide, and extend through corresponding openings in the carrier plate 10, beyond which the retaining claws are turned under.

In an advantageous development, each of the carbon brush holders 16a, 16b is held firmly on the carrier plate by the use of a sheet metal retainer 21 which is inserted between the underside of the carrier plate 10 and the turned under claws and which, having four perpendicularly extending projections takes over other carrier functions, details of which are given below. In attaching the holder there thus occurs a "sandwich arrangement" by virtue of the combination of metal (the holder), plastics material (the carrier plate) and metal (the retainer). Resitex (Registered Trade Mark) is preferably employed as the material for the carrier plate 10.

Each carbon brush holder has at the top a slot 23 which allows an electrical connection lead 24, connected to the top of the carbon brush, to pass through and to move along the slot with the gradual wear of the carbon brushes. Raised tongues 25 are disposed on both sides of the slot 23 at the end of each holder and prevent the moving carbon brush connection lead 24 from becoming entangled with the holder. The inner holder wall receives the rectangular carbon brush with a close sliding fit; the resilient force on each carbon brush is applied by the wide helical spring 17a, 1 7b which is appropriately shaped for this purpose and is mounted at a location 26 near the associated carbon brush guide and which is seated on a beveled rear face 27 of the carbon brush. In this manner a force component is obtained which acts on the holder wall 28 in a transverse direction. A force which acts in the same direction and is to be attributed to the friction between the carbon brush and the commutator results at the inner end of the carbon brush so that the carbon brush as a whole always abuts the one holder wall 28 and is thus prevented from tilting.

It can be seen particularly well from Fig.

2b that the retainer 21, which is held beneath the carrier plate 10 by the retaining claws 19 of the carbon brush holder, has the abovementioned extended parts 30 and 31. The extended part 30 serves to support the helical spring and the extended part 31 forms a double support point for the attachment of electrical leads. A bent-over lobe 33 on the retainer tongue 31 serves for the terminal attachment of the carbon brush lead 24 (with subsequent soldering); a further portion 34 can be connected to an external current feed line.

A further retainer 35 is provided on the carrier plate 10, in addition to the mirror image arrangement of the carbon brush guide 16a having a holder and a retainer, which lies opposite the carbon brush guide 1 6b, explained above, the further retainer 35 being likewise attached on the carrier plate 10 by means of retaining claws, which are not shown, and having an upwardly projecting extended part 36 which is connected to a second current feed line. Starting from the retainer 35 in the region 37, an anti-interference choke coil 38 is disposed on the carrier plate 10 and its other connection is connected to the underside of the retainer associated with the carbon brush guide 16a. The terminal solder attachment points of the antiinterference choke coil are indicated in Fig.

2b by 38a and 38b. The front end of each carbon brush is provided with a slot 40, by means of which better operational performance characteristics result.

The beveled rear wall of each carbon brush has a non-beveled part so that a stop surface 41 is formed which prevents the springs from jumping out.

It has also already been mentioned above that the retainers 21 together with the tongue-shaped extended parts are spirng carriers and weld or solder point carriers as well as carriers of solder support points for an external current feed line. In an advantageous embodiment, shown in Figs. 3a and 3b, these retainers are constructed so that they are located as a whole with their solder or weld support points below the carrier plate 10. In this manner the entire soldering or welding operation, following the fastening of the electrical feed lines, can be successfully carried out in a single operation in a multioperation welding machine by means of dip soldering or welding and even the cleaning of the welded areas can be carried out from one side only, for example, by means of the mechanical action of brushes, without difficulty and without the necessity of having to turn over the brush carrier plate.

The preferred construction of the retainers can be seen particularly clearly in Fig. 3b.

The retainer 50, which is held by the retaining claws 19' of the carbon brush guide 16b', has a portion 51 which is first bent downwards and then guided, whilst forming a pocket-like protuberance 52, in a curve upwards again and through the carrier plate to form the outer connecting point 53. The carbon brush lead 28' is received in and firmly fixed in the terminal pocket 52; the same happens on the opposite side in the case of the terminal pocket 55 with the carbon brush lead 56 in relation to the other carbon brush guide. In a similar manner, all connection solder points for the anti-interference choke coil 38 are also formed on the retainer 35', disposed on the upper side of the carrier plate 10, to form a free support point.

Corresponding pocket-like enclosures 57 of retainers 35' and 57' of a further retainer (not shown) extend downwards and accommodate the connection wires of the anti-interference choke coil 38', initially under the action of a clamp, soldering (or welding) subsequently taking place by means of dipping (or welding in a multi-operation welding machine using a suitable mask cover) so that in one operation all pocket-like connection points which intially provide only a clamping action can be firmly soldered (welded). Furthermore the pocket 57' for the other connection end of the anti-interference choke coil 38' is advantageously formed directly and as one piece by the retainer 50' associated with the carbon brush guide 16a', of which retainer only the pocket 55 can be seen in Fig. rther advantageous development 3.

A funher advantageous development re- sides in the fact that the support point tongue 60, originating from the retainer 35, has, in order to accommodate the second external current feed line (the first being fixed at the support point tongue 53 which is a unitary part of the retainer 50), in addition to the central accommodating slot 61 for the wire to be inserted, a further two lateral recesses 62, 63, which extend somewhat at the level of the central slot 61. The attachment of the feed line wire then takes place as shown in Fig. 4; the wire is first led through the central slot 61, then, for example, bent to the right in the plane of the drawing behind the support tongue 60 and then, whilst also being inserted into the recess 62, is wound round the support point tongue 60 so far that the end of the wire is again inserted from behind into the central slot 61 and can be pressed forwards. In this manner a secure attachment is achieved which can still be soldered at a later time.

WHAT WE CLAIM IS: 1. A fuel feed unit comprising a roller cell pump and an electric motor for driving the pump, the pump and motor being enclosed in a housing, and the motor having carbon brushes received in brush guides constructed as tubular holders which are circumferentially closed and which are secured to a carrier plate by one-piece retaining claws extending through the carrier plate.

2. A fuel feed unit as claimed in Claim 1, in which a respective retaining member is associated with each brush holder and is located, on the side of the carrier plate remote from the associated brush holder, by retaining claws on the brush holders, the retaining members also forming support points for accommodating and supporting other circuit elements on the carrier plate.

3. A fuel feed unit as claimed in Claim I or 2, in which the or each retaining member has a retaining tongue which is bent outwards and guided through the carrier plate and supports a respective pressure spring for each of the brushes.

4. A fuel feed unit as claimed in any of Claims 1 to 3, in which a further retaining tongue, in the form of a bent-over terminal connection, supports a carbon brush lead leading to a respective one of said brushes and, where necessary, forms at the same time a solder support point for an external current feed line.

5. A fuel feed unit as claimed in any of Claims 1 to 4, in which the rear face of each brush is beveled in the operative area of an associated pressure spring in such a manner that, together with the transverse force created by friction of that brush with the commutator of the motor, the brush is pressed onto a lateral guide wall of the associated brush holder.

6. A fuel feed unit as claimed in any of Claims 1 to 5, in which raised tongues are provided on each brush guide end which prevent entanglement of the brush lead with the associated brush guide.

7. A fuel feed unit as claimed in any of Claims 1 to 6, including an additional retaining member which is located on the carrier plate to support an anti-interference choke coil and forms a second connecting tongue for the attachment of an external current feed line.

8. A fuel feed unit as claimed in any of Claims I to 7, in which all the solder points for the attachment of brush leads or antiinterference choke coil connections are disposed on the side of the carrier plate remote from the brush holders and are initially formed as terminal pockets constructed by bending, whereby dip soldering and brush cleaning of the regions to be soldered can each be carried out in a respective single operation.

9. A fuel feed unit as claimed in any one of claims I to 8 in which each brush holder is of rectangular cross-sectional configuration and is closed on all four sides.

10. A fuel feed unit constructed substantially as hereinbefore particularly described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. upwards again and through the carrier plate to form the outer connecting point 53. The carbon brush lead 28' is received in and firmly fixed in the terminal pocket 52; the same happens on the opposite side in the case of the terminal pocket 55 with the carbon brush lead 56 in relation to the other carbon brush guide. In a similar manner, all connection solder points for the anti-interference choke coil 38 are also formed on the retainer 35', disposed on the upper side of the carrier plate 10, to form a free support point. Corresponding pocket-like enclosures 57 of retainers 35' and 57' of a further retainer (not shown) extend downwards and accommodate the connection wires of the anti-interference choke coil 38', initially under the action of a clamp, soldering (or welding) subsequently taking place by means of dipping (or welding in a multi-operation welding machine using a suitable mask cover) so that in one operation all pocket-like connection points which intially provide only a clamping action can be firmly soldered (welded). Furthermore the pocket 57' for the other connection end of the anti-interference choke coil 38' is advantageously formed directly and as one piece by the retainer 50' associated with the carbon brush guide 16a', of which retainer only the pocket 55 can be seen in Fig. rther advantageous development 3. A funher advantageous development re- sides in the fact that the support point tongue 60, originating from the retainer 35, has, in order to accommodate the second external current feed line (the first being fixed at the support point tongue 53 which is a unitary part of the retainer 50), in addition to the central accommodating slot 61 for the wire to be inserted, a further two lateral recesses 62, 63, which extend somewhat at the level of the central slot 61. The attachment of the feed line wire then takes place as shown in Fig. 4; the wire is first led through the central slot 61, then, for example, bent to the right in the plane of the drawing behind the support tongue 60 and then, whilst also being inserted into the recess 62, is wound round the support point tongue 60 so far that the end of the wire is again inserted from behind into the central slot 61 and can be pressed forwards. In this manner a secure attachment is achieved which can still be soldered at a later time. WHAT WE CLAIM IS:

1. A fuel feed unit comprising a roller cell pump and an electric motor for driving the pump, the pump and motor being enclosed in a housing, and the motor having carbon brushes received in brush guides constructed as tubular holders which are circumferentially closed and which are secured to a carrier plate by one-piece retaining claws extending through the carrier plate.