GB2046642A

GB2046642A - Manufacture of an Armature for an Electric Motor

Info

Publication number: GB2046642A
Application number: GB8011450A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1979-03-30
Filing date: 1980-04-03
Publication date: 1980-11-19
Also published as: DE2912684C2; JPS55144739A; DE2912684A1; DE2914285A1; JPS55136840A

Abstract

For the production of a fuel resistant armature winding (4) for an electric motor for an electric fuel pump, the armature winding (4), which is preferably preheated and rotated is treated by drop-by-drop trickling with a substance comprising a fuel-resistant epoxy resin system. The armature (1) is subsequently dried and hardened at an elevated temperature. As a result the resin coating on the armature winding (4) and/or the core insulation (3) of the armature (1) remains stable even under the action of the fuel and does not tend to break away. <IMAGE>

Description

SPECIFICATION An Armature for an Electric Motor The present invention relates to a method of manufacturing a fuel resistant armature for an electric motor.

It It is known that the armature or armature components in electric motors, which constitute one composite assembly with a pump component driven by them preferably as a fuel supply unit, may be impregnated with a synthetic resin, in order to obtain not only the desired insulation but also mechanical strengthening in the region of the winding. However, there is the risk that under the action of fuel or possibly even only specific fuel components and under a possible increased temperature, breaking away of resin may occur at parts of the windings and/or at the core insulation of the armature, with the result that functional faults arise in such a fuel supply unit. The impregnation or coating of the armature of such electric motors is usually carried out in the form of a dip impregnation with suitable phenolic resins.

According to the present invention there is provided a method of manufacturing a fuel resistant armature for an electric motor, comprising the steps of trickling a substance comprising a fuel resistant epoxy resin onto the windings of the armature and thereafter subjecting the substance to an elevated temperature during the drying and hardening thereof.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawing which shows in side view and partially in section an armature of an electric fuel pump comprising an armature core and winding impregnated with a dripped-on resin.

Armatures of electric motors especially the armatures of electric motors which constitute, together with a pump part for the supplying of fuel, one composite unit, are provided with a fuelresistant, dripped-on resin impregnation.

An armature 1 comprises a central shaft or axle 2, an armature laminated core 3, an armature winding 4 and a commutator 5, the individual segments of which are electrically conductively connected to specific winding regions, as shown ,at 6. The rotatable part of the armature is journalled by means of a hollow shaft 7 with bearings 8 and 9 at its ends on the stationary axle F21 which can be secured in any desired manner within the housing of an electric fuel pump. The drive of a pump part (not shown) is effected by means of an entraining device 10, which is disposed at the end of the armature remote from the commutator and engages with entraining fingers 1 0a, 1 Ob into the rotating part of the pump.With the usual arrangement of the electric motor, this motor is situated together with the pump part driven by it-most frequently a side channel pump (regenerative pump) or roller cell pump-in common housing, so that the electric motor is traversed by the supplied fuel, which may perhaps be only under vacuum, and the armature revolves in the fuel. Thus mechanically extremely intimate contacts occur under the action of fuel between the entire armature region and the fuel, possibly at high temperatures. The resin mixture used for the impregnation comprises an epoxy resin and of a suitable hardener, preferably of 100 parts by weight epoxy resin and 45 parts by weight amine hardener.

For the purpose of drop-by-drop trickling impregnation of the winding 4 of the armature 1, the armature is preheated and rotated, and then the dripping-on onto the winding is carried out with the aforementioned epoxy resin system which rapidly penetrates into the cavities in the winding and bonds intimately with the winding and the other components of the armature onto which it is applied. The armature is then dried and hardened under the action of heat. The drawing shows diagramatically the dripped-on resin impregnation 11 on the armature winding. The dripped-on resin penetrates into and between the armature windings and stabilizes these and holds them together.

The above described embodiment of the present invention has the advantage that resin break-aways at windings and/or core insulation no longer occur and the production of the armature can be carried out more rapidly and more rationally than hitherto without long drying and hardening phases.

By the use of a fuel-resistant epoxy resin system, which is trickled drop-by-drop onto the winding, a fuel-resistant impregnation is obtained, wherein by preheating the armature the bonding of armature components and windings to the dripped-on epoxy resin which may also contain an amine hardener, is intimately formed and resistant to separation.

Claims

1. A method of manufacturing a fuel resistant armature for an electric motor, comprising the steps of trickling substance comprising a fuel resistant epoxy resin onto the windings of the armature and thereafter subjecting the substance to an elevated temperature during the drying and hardening thereof.

2. A method as claimed in claim 1, comprising the steps of heating the armature prior to applying the substance thereto and rotating the armature during the application of the substance.

3. A method as claimed in either claim 1 or claim 2, wherein the substance is an epoxy resin system comprising 100 parts by weight of an epoxy resin and 45 parts by weight of an amine hardener.

4. A method of manufacturing a fuel resistant armature for an electric motor, the method being as claimed in any one of the preceding claims and substantially as hereinbefore described with reference to the accompanying drawing.

5. An armature for an electric motor, when manufactured by the method as claimed in any one of the preceding claims.

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION An Armature for an Electric Motor The present invention relates to a method of manufacturing a fuel resistant armature for an electric motor. It It is known that the armature or armature components in electric motors, which constitute one composite assembly with a pump component driven by them preferably as a fuel supply unit, may be impregnated with a synthetic resin, in order to obtain not only the desired insulation but also mechanical strengthening in the region of the winding. However, there is the risk that under the action of fuel or possibly even only specific fuel components and under a possible increased temperature, breaking away of resin may occur at parts of the windings and/or at the core insulation of the armature, with the result that functional faults arise in such a fuel supply unit. The impregnation or coating of the armature of such electric motors is usually carried out in the form of a dip impregnation with suitable phenolic resins. According to the present invention there is provided a method of manufacturing a fuel resistant armature for an electric motor, comprising the steps of trickling a substance comprising a fuel resistant epoxy resin onto the windings of the armature and thereafter subjecting the substance to an elevated temperature during the drying and hardening thereof. An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawing which shows in side view and partially in section an armature of an electric fuel pump comprising an armature core and winding impregnated with a dripped-on resin. Armatures of electric motors especially the armatures of electric motors which constitute, together with a pump part for the supplying of fuel, one composite unit, are provided with a fuelresistant, dripped-on resin impregnation. An armature 1 comprises a central shaft or axle 2, an armature laminated core 3, an armature winding 4 and a commutator 5, the individual segments of which are electrically conductively connected to specific winding regions, as shown ,at 6. The rotatable part of the armature is journalled by means of a hollow shaft 7 with bearings 8 and 9 at its ends on the stationary axle F21 which can be secured in any desired manner within the housing of an electric fuel pump. The drive of a pump part (not shown) is effected by means of an entraining device 10, which is disposed at the end of the armature remote from the commutator and engages with entraining fingers 1 0a, 1 Ob into the rotating part of the pump.With the usual arrangement of the electric motor, this motor is situated together with the pump part driven by it-most frequently a side channel pump (regenerative pump) or roller cell pump-in common housing, so that the electric motor is traversed by the supplied fuel, which may perhaps be only under vacuum, and the armature revolves in the fuel. Thus mechanically extremely intimate contacts occur under the action of fuel between the entire armature region and the fuel, possibly at high temperatures. The resin mixture used for the impregnation comprises an epoxy resin and of a suitable hardener, preferably of 100 parts by weight epoxy resin and 45 parts by weight amine hardener. For the purpose of drop-by-drop trickling impregnation of the winding 4 of the armature 1, the armature is preheated and rotated, and then the dripping-on onto the winding is carried out with the aforementioned epoxy resin system which rapidly penetrates into the cavities in the winding and bonds intimately with the winding and the other components of the armature onto which it is applied. The armature is then dried and hardened under the action of heat. The drawing shows diagramatically the dripped-on resin impregnation 11 on the armature winding. The dripped-on resin penetrates into and between the armature windings and stabilizes these and holds them together. The above described embodiment of the present invention has the advantage that resin break-aways at windings and/or core insulation no longer occur and the production of the armature can be carried out more rapidly and more rationally than hitherto without long drying and hardening phases. By the use of a fuel-resistant epoxy resin system, which is trickled drop-by-drop onto the winding, a fuel-resistant impregnation is obtained, wherein by preheating the armature the bonding of armature components and windings to the dripped-on epoxy resin which may also contain an amine hardener, is intimately formed and resistant to separation. Claims

6. A fuel supply unit comprising a fuel pump and an electric motor provided with an armature as claimed in claim 5 and drivably connected to the fuel pump, a housing containing the electric motor and the fuel pump and passage means within the housing for fuel to flow through the electric motor.