GB1592619A - Electrical fuel feed units - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO ELECTRICAL FUEL FEED UNITS (71) We, ROBERT BOSCH GmbH, a German company of Postfach 50, 7 Stuttgart 1, 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 electrical fuel feed units of the type which include a fuel feed pump and an electric motor for driving the pump.

A fuel feed unit is known which employs a roller cell pump and in which the pump and the electric motor are disposed axially behind each other within a housing and the electric motor drives the roller cell pump either by way of a common shaft or by way of a bush which slides on a stationary shaft and positively engages a rotational element in the roller cell pump. The fuel which is sucked in by the roller cell pump also flows through the area of the electric motor to cool it and passes under pressure to an outlet connecting member. The design of the electric motor is of a conventional nature. A brush carrier plate is provided on which are mounted brushes which slidably engage the motor commutator. Such a fuel feed pump develops interference voltages which are to be attributed not least to the formation of sparks at the carbon brush/commutator/junction. For this reason the known pumps have one or more antiinterference devices such as anti-interference choke coils (with iron cores) built into the two feed lines as well as, for example, an anti-interference capacitor above the two connection pins. These anti-interference elements and assembled in the known fuel feed pumps so that they hang freely into the pump chamber, held by their connecting wires, with the connecting wires preferably secured on the carrier plate for the brushes or on the plug socket.

Due to robust operation and other vibrations, breaks can occur in the connecting wires so that the supply of current to the pump unit fails; it is also possible as a result of vibrations for the choke coil cores to fall out of the choke coil and cause damage to the electric motor and other parts in the interior of the housing. Furthermore, the fuel may adversely affect the anti-interference elements which may have a disadvantageous effect on their electrical behaviour.

In accordance with the present invention, there is provided an electric fuel feed unit which includes a fuel feed pump and an electric motor for driving the pump, the pump and the motor being disposed within a housing on which a plug socket made of plastics material and accomodating electrical feed lines for the motor is disposed, at least parts of one or more electrical anti-interference devices being disposed in the plug socket and embedded within the plastics material thereof.

If the or each anti-interference devices, particularly anti-interference choke coils, is completely enclosing in the plastics material, vibration is no longer a problem so that breaks in the wire can no longer take place.

By injection moulding around the antiinterference devices, for example using the plastics material from which the plug socket itself is made, choke coil cores can no longer fall out of the coil which is thus protected entirely against any breakage and damage.

The injection-moulding using plastics material prevents any adverse effect on antiinterference choke coils or anti-interference capacitors by the fuel and ensures satisfactory electrical insulation of one part from another and from the surroundings.

Advantageously, at least the feed lines of the or each anti-interference device comprise baked varnished wires, each of which is provided with a plastics coating and is constructed so that, due to the effect of heat during the injection moulding of plug socket fusion or adhesion of the baked varnish layer with the plastics material of the plug socket takes place. In this manner a satisfactory sealing of the plug element against the effects of the fuel located under pressure in the interior of the housing is achieved.

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Fig. I is an end view of a fuel feed pump in accordance with the invention; Fig. 2 is a longitudinal section through the fuel feed pump of Fig. I; Fig. 3 is a section along the line Ill-Ill in Fig. 2; and Fig. 4 is an enlarged sectional representation of the plug socket.

The reduced size view of Fig. I shows a fuel feed pump which comprises a housing I having a vacuum connecting member 2 and an outlet connecting member 3' as well as a socket 3 which is connected to the vehicle electrical supply by way of a suitable feed line having a two-pin plug. It can be seen from the longitudinal section of Fig. 2 that the plug socket 3 is supported in the housing 1 between the area forming a roller cell pump 4 and a carrier plate 5 for the carbon brushes of an electric motor 6. The commutator of the electric motor 6 is denoted by the reference numeral 7; the electric motor 6 drives a shaft 8 which extends forward towards the vacuum connecting member 2 up to the roller cell pump 4 and drives the latter by way of a driver wedge 9. The common shaft 8 is journalled in suitable bearings 9a and 9b. The roller cell pump and the electric motor which drives it do not constitute the principal subject-matter of the present invention and thus they, as well as the flow of the fuel fed by the pump, do not require any further explanation.

Fig. 3 is a sectional end view of the housing showing the brush carrier plate 5 in plan with slide guides 1 0a and 10b for the brushes 11 a and 11 b which abut the commutator 7. The current feed lines to the brushes are denoted by the reference numerals 12a and 12b.

Because of the necessity to suppress electrical interference generated by such a fuel feed pump, anti-interference elements are provided which comprise anti-interference choke coils which are disposed in series with the connecting wires at the positive and/or the negative end. In addition, a capacitor can also be connected across the two connecting pins. The two connecting pins are denoted in Fig. 1 by the reference numerals 13a and 13b and may be flat plug pins as illustrated, made of a suitable conducting metal, which are held by the plastic material of the plug socket and are cast in it.

As shown in Fig. 4, the connecting contact 13a leads to an anti-interference choke coil 15, via an intermediate connection 14, disposed within the plastics material of the plug socket 3, so that this anti-interference choke coil is completely embedded in the plastics material of the plug socket 3. Its production can thereby be undertaken in such a manner that the mechanical assembly comprising the connecting contacts 13a (13b) and the antiinterference elements are laid in a mould and a suitable plastics material is injection moulded therearound.

The plastics material can be a fuel-resistant compound such as a polyamide which also has sufficient strength to support the elements mounted in the interior of the socket. The anti-interference choke coil 15 has a choke core 16 which is held securely; the connecting end 17 of the anti-interf,er- ence coil exits from the plug socket 3 and is guided in the interior of the fuel feed pump, as shown in Fig. 2, to a suitable connection to the brush connection to the brush carrier plate 5.

As shown in Fig. 4, an anti-interference choke coil is disposed only in the one feed line branch; the other feed line branch 18 terminates in a free connecting wire 19. In other embodiments anti-interference choke coil; likewise an anti-interference capacitor can be disposed within the plug socket, shown in Fig. 4, as shown by the dashed lines at position 20.

In the embodiment shown, a second antiinterference choke coil 21 is preferably provided which is located on the brush carrier plate 5 without the use of long wires. This method of assembly avoids a situation where anti-interference choke coils, held only by their connecting wires, project freely into the pump chamber (see Fig. 3).

Referring further to Fig. 3, the feed lines are led in such a manner that the connecting wire 17, connected in series with the antiinterference choke coil 15 in the plug socket 3, is guided so that it emerges from underneath the brush carrier plate 5 to the support point 25 which is formed by a sheet metal member 26 which projects upwards from below the carrier plate 5 and which primarily serves to connect the sliding guide 10b of the carbon brush 1 lb. The other connecting wire 19 is guided through an opening 27 in the carrier plate 5 and secured on a raised support point 28; this support point 28 is part of a mounting member 29 at whose other end area 29a the second anti-interference choke coil 21 is attached, by clamping and subsequent soldering; the other attachment point of the anti-interference choke coil 21 is guided through an opening 30 in the plate 5 and is connected below the plate directly to a flange of a support member for the second carbon brush guide 10a, this not being visible in the drawings. In this manner, the second anti-interference choke coil 21 is held se curely and undislodgeably on the carrier plate 5.

In other embodiments, a potential leakage of fuel in the region of the anti-interference elements embedded into the plug socket during injection moulding, is prevented by the use of a so-called baked varnished wire for the feed line wires which is constructed in the form of an inner strand with a plastics coating. The plastics coating becomes adhesive when melted and may comprise a thermoplastic or a heat-setting plastics material for example a thermoplastic polyamide or a heat-setting plastics material which is known under the name of "Esterimid". The manufacturer of such baked varnished wires is the company Lackdrahtunion or the company Lacroix and Kress. The baked varnish layer on the wire feed line of the antiinterference elements is melted during the injection moulding process and melts internally with the plastics material so that a perfect seal against the effect of fuel, and an over-all more reliable attachment, can generally be achieved in the case of such injection moulded wires and parts.

WHAT WE CLAIM IS: 1. An electric fuel feed unit which includes a fuel feed pump and an electric motor for driving the pump, the pump and the,motor being disposed within a housing on which a plug socket made of plastics material and accommodating electrical feed lines for the motor is disposed, at least parts of one or more electrical anti-interference devices being disposed in the plug socket and embedded within the plastics material thereof.

2. A fuel feed unit as claimed in claim 1 in which the or each anti-interference device is embedded within the plastics material of the socket by having said plastics material injection moulded therearound during formation of the socket.

3. A fuel feed unit as claimed in claim 1 or 2 in which the or each anti-interference element comprises an anti-interference choke coil and/or an anti-interference capacitor and in which the or each anti-interference element, together with terminal connections thereof with externally projecting components, are wholly embedded within said plastics material of the plug socket.

4. A fuel feed unit as claimed in claim 1, 2, or 3 in which an anti-interference choke coil is disposed in series with each of a positive and a negative feed line and an antiinterference capacitor is disposed within the plug socket in parallel with external electrical contacts.

5. A fuel feed unit as claimed in claim 1, 2 or 3, in which only one anti-interference choke coil is disposed in the plug socket and a second anti-interference choke coil, is supported on a carrier plate for brushes of the electric motor.

6. A fuel feed unit as claimed in claim 5 in which said other anti-interference choke coil is soldered by its terminal connections onto sheet-metal elements connected to the brush carrier plate.

7. A fuel feed unit as claimed in any of claims 1 to 6, in which at least the feed lines of the or each anti-interference device comprise baked varnished wires each of which is provided with a plastics coating and is constructed so that, due to the effect of heat during the injection moulding of the plug socket a fusion or adhesion of the baked varnish layer with the plastics material of the plug socket takes place.

8. A fuel feed unit 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 (8)

**WARNING** start of CLMS field may overlap end of DESC **. curely and undislodgeably on the carrier plate 5. In other embodiments, a potential leakage of fuel in the region of the anti-interference elements embedded into the plug socket during injection moulding, is prevented by the use of a so-called baked varnished wire for the feed line wires which is constructed in the form of an inner strand with a plastics coating. The plastics coating becomes adhesive when melted and may comprise a thermoplastic or a heat-setting plastics material for example a thermoplastic polyamide or a heat-setting plastics material which is known under the name of "Esterimid". The manufacturer of such baked varnished wires is the company Lackdrahtunion or the company Lacroix and Kress. The baked varnish layer on the wire feed line of the antiinterference elements is melted during the injection moulding process and melts internally with the plastics material so that a perfect seal against the effect of fuel, and an over-all more reliable attachment, can generally be achieved in the case of such injection moulded wires and parts. WHAT WE CLAIM IS:

1. An electric fuel feed unit which includes a fuel feed pump and an electric motor for driving the pump, the pump and the,motor being disposed within a housing on which a plug socket made of plastics material and accommodating electrical feed lines for the motor is disposed, at least parts of one or more electrical anti-interference devices being disposed in the plug socket and embedded within the plastics material thereof.

2. A fuel feed unit as claimed in claim 1 in which the or each anti-interference device is embedded within the plastics material of the socket by having said plastics material injection moulded therearound during formation of the socket.

3. A fuel feed unit as claimed in claim 1 or 2 in which the or each anti-interference element comprises an anti-interference choke coil and/or an anti-interference capacitor and in which the or each anti-interference element, together with terminal connections thereof with externally projecting components, are wholly embedded within said plastics material of the plug socket.

4. A fuel feed unit as claimed in claim 1, 2, or 3 in which an anti-interference choke coil is disposed in series with each of a positive and a negative feed line and an antiinterference capacitor is disposed within the plug socket in parallel with external electrical contacts.

5. A fuel feed unit as claimed in claim 1, 2 or 3, in which only one anti-interference choke coil is disposed in the plug socket and a second anti-interference choke coil, is supported on a carrier plate for brushes of the electric motor.

6. A fuel feed unit as claimed in claim 5 in which said other anti-interference choke coil is soldered by its terminal connections onto sheet-metal elements connected to the brush carrier plate.

7. A fuel feed unit as claimed in any of claims 1 to 6, in which at least the feed lines of the or each anti-interference device comprise baked varnished wires each of which is provided with a plastics coating and is constructed so that, due to the effect of heat during the injection moulding of the plug socket a fusion or adhesion of the baked varnish layer with the plastics material of the plug socket takes place.

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