GB2271220A

GB2271220A - Electrical connector with radio interference suppression.

Info

Publication number: GB2271220A
Application number: GB9319735A
Authority: GB
Inventors: Thomas Wizemann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1992-10-02
Filing date: 1993-09-24
Publication date: 1994-04-06
Also published as: GB9319735D0; DE4233132A1; FR2696587A1; JPH06209544A

Abstract

In the case of an electrical commutator machine with radio interference suppression, in particular a commutator motor for motor vehicle use, to improve radio interference suppression, neighbouring bars 12 of a commutator 11 are electrically connected to one another by a resistor. The resistor connection may be produced either by discrete resistor elements 17 or by an electrically conductive casting compound, in which the commutator bars 12 are embedded. The commutator may be in an electric motor for use in a motor vehicle, particularly in a fuel pump. <IMAGE>

Description

Electrical commutator machine with radio interference suppression

Prior Art

The invention is based on an electrical commutator machine with radio interference suppression, in particular a commutator motor for motor vehicle use. of the generic type defined in the precharacterizing clause of Claim 1.

commutator or collector machines are used as electric drive motors in a variety of ways in a motor vehicle, including as immersed motors in fuel pumps. During operation, such commutator machines emit a highfrequency interference spectrum. caused by the switch-off pulses of the armature winding during the transition of current conduction from one commutator bar to the other. It is therefore necessary to provide such commutator machines with interference suppression.

In the case of a known collector motor of this type (DE 29 21 815 C2), for this purpose on the one hand radio interference-suppression capacitors are connected to the commutator brushes and their common earth terminal is connected to the stator core of the motor, and on the other hand, in addition, two non-magnetic pieces are arranged in such a way that they f orm, a bridge between the edge sections of the poles of the two-pole stator pole and surround the armature. The non-magnetic pieces have the ef f ect of achieving an additional lowering of the interf erence voltage by 4 - 5 dB over a large f requency range. However,, the arrangement of such pieces 1 inside the motor causes a not inconsiderable increase in production expenditure.

Advantages of the invention The electrical commutator machine according to the invention, having the characterizing features of Claim 1, has the advantage thatt due to the resistors between the commutator bars, the free-wheeling voltage of the armature winding is loaded, so that the arcs between the commutator bars and the commutator brushes, causing the radio interference, are produced less intensively and consequently with less energy. The residual energy is converted in the resistors into heat and is dissipated without any problems via the commutator bars to the surroundings or, in the case of electric fuel pumps, to the fuel in which the collector is immersed. As measurements show,, in this way the interference voltage can be lowered in a broad frequency range up to 15 dB in comparison with- commutator motors provided with conventional interference suppression by capacitors and coils on the commutator brushes. Although the losses in the resistors reduce the efficiency of the machine somewhat, this is nothing in relation to the gain in interference suppression accomplished.

Claims

Advantageous further developments and improvements of the commutator

machine specified in Claim 1 are possible by the measures listed in the further claims.

According to one embodiment of the invention, the resistor connection of the commutator bars can be produced by discrete resistor elements, the two terminal wires of which are soldered onto neighbouring commutator bars. The resistor elements are in this case preferably soldered onto the terminal lugs which serve for connecting the armature winding to the individual commutator bars.

Better suited for mass production is a preferred embodiment of the invention, in which the resistor connection between the commutator bars is achieved by the casting compound used for mechanical fastening of the commutator bars being designed to be electrically conductive with the desired resistance value. Instead of the casting compound, it is also possible for an adhesive used for fastening the commutator.bars to be designed to be electrically conductive. The production expenditure for the commutator motor provided with interference suppression is no greater than that for the commutator motor not provided with interference suppression.

Drawing The invention is explained in more detail in the following description with reference to exemplary embodiments represented in the drawing, in which:

Fig. 1 shows a perspective representation of a commutator of a commutator motor provided with radio interference suppression, in diagrammatic form, Fig. 2 shows a longitudinal section of the commutator in Fig. 1, Fig. 3 shows a similar representation as in Fig. 2 of a commutator according to a further exemplary embodiment.

Description of the exemplary embodiments A commutator motor as an example of a general electrical commutator machine is known in its construction and mode of operation, so that in Fig. 1 only the commutator 11 of the commutator motor is shown perspectively. the said commutator being seated in a rotationally fixed manner on the motor shaft 11, which also bears the motor armature with the armature winding. In a known way, the commutator 11 has a multiplicity of commutator bars 12, which are separated from one another by slots 13. The bars 12 are arranged next to one another, distributed uniformly over the circumference, and are embedded in an electrically insulating casting com- pound 14 (Fig. 2). The casting compound 14 encloses the motor shaft 10 in a rotationally fixed manner. On the end face 111 of the commutator 11 facing the armature winding 10. the bars 12 respectively bear a terminal lug 15 - 4 for the armature winding. in each case one end of a coil of the armature winding is connected to a terminal lug 15. The f astening of the coil ends 16, 17 (Fig. 2) is performed by bending the terminal lugs 15 over onto the bars 12, whereby in each case a coil end 16 is firmly pinched between the terminal lug 15 and the surface of the bar 12.

For radio interference suppression of the commutator motor, the respectively neighbouring bars 12 of the commutator 11 are connected electrically conductively via one resistor each. In the case of the commutator represented in Figs. 1 and 2, the resistor connection of the bars 12 is realized by discrete resi.stor elements 17. Each resistor element 17 is soldered by its two terminal wires onto the terminal lugs 15 of two neighbouring bars 12.

In Fig. 3, a modified commutator 111. which is better suited for mass production, is represented in longitudinal section. The construction of the commutator 11' is the same as described with respect to Fig. 1. The interference suppression of the commutator motor is likewise effected by the bars 12 of the commutator 111 being connected to one another electrically conductively via resistors. In contrast to the commutator 11 in Figs. 1 and 2, however, this resistor connection is not produced with discrete resistor elements. but is accomplished by the casting compound 141 being designed to be electrically conductive, its electrical resistance corresponding to the resistance value required for the radio interference suppression.

Claims 1. Electrical commutator machine with radio interference suppression, in particular commutator motor for motor vehicle use, having a commutator 111;111) which is connected to an armature winding and has a multiplicity of commutator bars (12) arranged insulated from one Another on its circumference, characterized in that neighbouring bars (12) are respectively connected to one another electrically conductively via a resistor.
2. - Machine according to Claim 1. characterized in that the resistor connection of the commutator bars (12) is produced by discrete resistor elements (17), the two terminal wires of which are soldered onto neighbouring commutator bars (12).
3. Machine according to Claim 2r character ized in that, for connection of the armature winding, the commutator bars (12) bear on their end face facing the armature winding terminal lugs (15) and in that the discrete resistor elements (17) are soldered onto the terminal lugs-(15).
4. Machine according to Claim 1, characterized in that, for mechanical fixing, the commutator bars (12) are embedded in a casting compound (141) or adhesively bonded in and in that, for resistor connection of the commutator bars (12), the casting compound (141) and/or the adhesive are designed to be electrically conductive.
5. An electrical commutator machine substantially as herein described with reference to Figures 1 and 2, or Figure 3, of the accompanying drawings.