CN102565700B - For monitoring equipment and the method for the brush wear of commutator system in motor - Google Patents

Abstract

The invention relates to a device and a method for monitoring brush wear of a commutator system in an electric machine, in which device the brushes are accommodated adjustably in a brush holder and directed by a spring element in the direction of the current collector A force is applied and the device is constructed such that as a defined wear travel is reached, the contact area between the brush and the current collector changes, which can be detected by measurements.

Description

Apparatus and method for monitoring brush wear of a commutator system in an electric machine

technical field

The present invention relates to an apparatus and method for monitoring brush wear of a commutator system in an electric machine.

Background technique

It is known from DE 10 2004 035 318 A1 to determine the wear of the carbon brushes of an electric motor as a function of the number of revolutions of the electric motor. In this case, the rotor revolutions during operation of the motor are summed or derived from the detected voltage values. If the number of revolutions exceeds a certain critical value, a warning signal is output.

It is known from DE 10 2005 061 412 A1 that the brushes of a commutator are designed as a two-component component with a plurality of sections with different electrical conductivity. The difference in impedance in the measurement signal is recorded by the impedance sensor during the continuous wear of the brushes, which can be displayed. A prerequisite, however, is a brush structure with two parts of different conductivity.

Contents of the invention

It is an object of the invention to be able to reliably detect brush wear in the commutator of an electric motor using simple measures.

This object is achieved according to the invention by the features of the independent claims. The dependent claims give advantageous developments.

A device or a method according to the invention is used for monitoring the wear of brushes in electric machines, such as electric motors or generators. In one advantageous application, the device for monitoring wear is used in a starter motor of an internal combustion engine.

The commutator system comprises a plurality of brushes for transmitting current, wherein at least one brush is accommodated adjustably in a brush holder and is urged by a spring element in the direction of the current collector. By means of embodiments known per se, the brushes are aligned in the direction of the current collector in the event of brush wear, so that a reliable current transmission between the brushes and the rotating current collector is guaranteed over long operating times.

In the device according to the invention, at least one brush has a defined, preferably maximum wear travel, seen in the adjustment direction of the brushes, wherein the contact area between the brush and the current collector decreases as the defined wear travel is reached. Change. The attainment of a defined wear path is detected via measured values.

This embodiment makes it possible to use brushes made of a single brush material, since the measured value for detecting a defined wear path is independent of material differences, but only the advance traveled by the brush. This feed rate can be sensed either mechanically, for example by reaching a stop and triggering contact, or according to a preferred embodiment electrically by detecting electrical characteristic values of the motor which vary due to the different contact areas. Variety.

According to a preferred embodiment, the contact area decreases upon reaching a defined wear path, which is also the case here when the contact between the brush and the outer peripheral surface of the collector is interrupted. As a result of the contact area being reduced or the contact being interrupted, at least one electrical characteristic value changes, which can be determined by a corresponding measuring device or electronic device. The reduction of the contact area leads to an increase in the resistance and thus to a reduction in the voltage drop in the electrical circuit of the vehicle, which can be determined and then, for example, a signal is displayed that the wear stroke of the brush has been exhausted and a replacement of the brush is awaited.

According to a preferred embodiment, at least two brushes of the electric machine have different defined wear paths, so that these wear paths are reached at different points in time with approximately the same wear. As soon as the brush with the reduced defined wear path is used to the extent that the contact area between the brush and the collector changes, a corresponding signal is displayed, while the brush with the longer defined wear path is still always in contact with the collector. Electrical contacts and transfer current. The current transmission can therefore be maintained substantially even in the event of continued wear and the current state of wear can be displayed to the user. Despite the wear of at least one brush, the electric machine can continue to operate completely or at least only to a slightly reduced extent.

According to an advantageous embodiment, the advance of at least one brush is limited in the direction of the current collector to a maximum permissible wear path, in particular by means of a stop. The stop is advantageously located on the brush holder, or alternatively on another component on the housing side. In order to limit the feed rate, either the adjustment movement of the spring element is limited such that when the stop is reached, the force no longer via the spring element continues to exert force on the brush in the direction of the current collector. According to a further embodiment, the adjustment movement of the brush is limited by a stop, so that the brush, which is forced by the spring element in the direction of the collector, reaches the maximum permissible wear path when the stop is reached, the brush and the collector The contact area between is also either reduced or the contact is completely interrupted. The stop is formed on the brush holder, for example in the form of an inwardly facing collar, which limits the feed rate in a desired manner.

According to another advantageous embodiment of the stop for limiting the feed movement, which is not strictly necessary, the brush body has a wear segment with a constant cross-sectional area and a plurality of different cross-sections compared to the wear segment The base segment of the area. The wear segment is subjected to permissible wear, wherein, as the wear segment is exhausted, the base segment comes into contact with the current collector and, due to the base segment having several non-identical cross-sectional areas, the electrical characteristic values, especially the voltage in the motor, occur Changes can be recorded. In particular, the base section has a smaller cross-sectional area than the wear section, wherein in principle it is also conceivable for the base section to have a larger cross-sectional area.

According to another advantageous embodiment, the electric machine has a plurality of brush pairs each having two brushes, wherein at least one brush of a brush pair, but advantageously both brushes of this brush pair have a maximum permissible The wear stroke is different from other brush pairs. In particular, the brush or both brushes of the brush pair have a shortened maximum wear path in order to be able to indicate wear at an early stage without impairing the performance of the electric machine. For example, in six-pole motors a brush system with six carbon brushes is used, in which the two carbon brushes of a brush pair have a reduced wear path, so that only one more stroke is reached as the maximum wear path of the brush pair is reached. Four carbon brushes transmit the current, which can be detected by the raised total resistance.

The electrical characteristic values from which the wear-critical regions can be determined are on the one hand the voltage disturbances when the motor is switched on and on the other hand the prolonged coasting time of the motor after the power supply has been switched off.

After at least one, but advantageously two carbon brushes with a reduced wear path no longer bear against the outer peripheral surface of the current collector and thus no longer wear, although the wear of the remaining carbon brushes increases slightly, this still allows There is enough time for maintenance work and brush replacement.

Advantageously, both the positive and the negative brushes in the brush pair have a reduced wear path in order to avoid polarity overloading and thus rapid wear. Preferably, the wear distances within a brush pair are equal in size, wherein in principle also the different wear distances, which are respectively reduced compared to the other brushes, are taken into account in order to compensate, for example, the differences within the brush pairs in a targeted manner. abrasion behavior.

As long as at least two brush pairs are provided in the electric machine, it is advantageous if only the two brushes of a single brush pair have a reduced wear path. However, it is also conceivable that several brush pairs, but not all brush pairs, have a reduced amount of wear, wherein the shortened wear distances can be equal or unequal in order to indicate the degree of brush failure, for example in a graded approach incrementally.

Description of drawings

Further advantages and advantageous embodiments emerge from the further claims, the description of the figures and the figures. in:

Figure 1 shows a sectional view of the commutation system in an electric machine with carbon brushes which are accommodated adjustably in a brush holder and are forced by spring elements in the direction of the outer circumference of the current collector ,

Figure 2 shows a reversing system in which the wear stroke of the carbon brushes is limited by a stop on the brush holder,

Figure 3 shows another reversing system in which spring movement is limited by stops,

Figure 4 shows another embodiment in which the wear stroke of the carbon brush is limited as in Figure 2, wherein the stop is located on the tangential side wall of the brush holder,

FIG. 5 shows another commutation system in which the brushes have sections of reduced cross-sectional area.

Identical parts have the same reference numerals in the figures.

detailed description

The commutation system 1 according to FIG. 1 is a component of an electric machine 2 shown only schematically, for example a starter motor for an internal combustion engine. The commutation system 1 comprises carbon brushes 3 , which are accommodated adjustably in a brush holder 4 on the housing side, and a current collector 5 which is fixedly connected to the rotor of the electric machine 2 . The rotor axis, about which the current collector 5 also turns, is indicated with reference numeral 6 .

The carbon brushes 3 , which are adjustably accommodated in the brush holder 4 , are forced by the force of the spring element 7 in the direction of the outer peripheral surface of the collector. The spring element 7 is likewise accommodated in the brush holder 4 . The adjusting movement of the carbon brushes 3 and the direction of action of the spring elements 7 are radial to the rotor longitudinal axis 6 . Power is supplied to the brushes 3 via the twisted wire 8 .

Due to the radial adjustability of the carbon brushes 3 in the brush holder 4 and the application of the force of the spring element 7 , the carbon brushes 3 are automatically aligned radially in the direction of the current collector 5 during wear.

FIG. 2 shows a reversing system 1 which largely corresponds to the reversing system according to FIG. 3 The limited maximum wear stroke. The stop is formed by a stop element 9 on the brush holder 4 and a brush-side stop element 10 . According to the tangential view of the commutation system in FIG. 2 , the stop elements 9 and 10 on the brush holder 4 or on the carbon brushes 3 extend in the axial direction. On the side of the brush holder 4, the stop element 9 forms an inwardly facing flange on the lower end face of the brush holder 4, which corresponds to the stop element 10 on the carbon brush 3, wherein the stop element 10 is opposite It protrudes from the brush base in the axial direction, and is located on the side of the brush away from the contact surface with the collector in the radial direction. The positions of the stop elements 9 and 10 are aligned relative to each other so that the carbon brushes in the commutation system 1 according to FIG. 2 have a smaller maximum wear travel compared to the commutation system according to FIG. 1 , viewed in the radial adjustment direction. . As soon as the stop element 10 on the carbon brush 3 comes into contact with the stop element 9 on the brush holder 4 , further radial advance in the direction of the current collector 5 is interrupted. As a result, the sliding contact between the end faces of the carbon brush 3 and the outer peripheral face of the current collector 5 is interrupted, so that no further current can be transmitted through the carbon brush. As long as the electric machine is supplied with electricity by other carbon brushes with greater wear length, for example via carbon brushes within the scope of the commutation system according to FIG. 1 , the further power supply is carried out only by these carbon brushes with greater wear length. A change in the power supply due to the failure of a carbon brush or a pair of carbon brushes with a reduced wear path can be determined from the electrical characteristic values.

In the exemplary embodiment according to FIG. 3 , it is not the adjustment travel of the carbon brush 3 that is reduced by the stop element 9 , but the adjustment travel of the spring element 7 . As soon as the carbon brush 3 has traversed the corresponding wear path, the force of the spring element 7 is thus supported against the inwardly pointing stop element 9 on the brush holder 4 . By being supported on the stop element 9, the spring element 7 loses its effect on the carbon brush 3, so that this carbon brush is no longer exerted radially in the direction of the outer peripheral surface of the current collector 5, and the carbon brush stays where it reaches Location. In this way, the wear path of the carbon brushes 3 is also limited.

FIG. 3 shows a view of the commutator system 1 along the axial direction, similarly to FIG. 4 . The rotational movement of the current collector 5 and correspondingly of the rotor of the electrical machine is indicated by arrow 11 . The stop element 9 is located on the inside of the brush holder 4 adjacent to the free end face of the brush holder, ie on the circumferential side wall.

Similar to FIG. 2 , in the exemplary embodiment according to FIG. 4 the advance path of the carbon brush 3 is limited. For this purpose, the stop elements 9 and 10 on the brush holder 4 or on the carbon brushes 3 interact. However, unlike FIG. 2, the stop elements 9, 10 are not located on the axial end faces of the brush holder or the carbon brushes, but on the circumferential surface, so that the carbon brushes and the brush holders can be configured accordingly in the axial direction. shorter.

In the exemplary embodiment according to FIG. 5 , the wear path of the carbon brush 3 is limited by providing recesses 14 in the carbon brush inside the carbon brush body. The carbon brush body is divided radially into a base section 12 away from the current collector 5 and a wear section 13 facing the current collector 5 , wherein the wear section extends between the contact surface with the current collector and the base section 12 . The base section 12 has a smaller cross-sectional area in the region of the recess 14 than the wear section 13 , which has a constant cross-sectional area over its radial extent. Once the worn section has been completely eroded away by abrasion, the base section 12 comes into contact with the outer peripheral surface of the current collector 5 in the area of the recess with a reduced cross-sectional area. Changes in the electrical characteristic values in the motor due to the reduced cross-sectional area can be displayed to determine wear over a period of time. The reduced cross-sectional area of the carbon brushes 3 causes an increase in resistance and voltage disturbances, which can be measured.

Claims (14)

1. the mill being used for monitoring the brush (3) of commutator system (1) in motor (2) The equipment damaged, wherein said brush (3) can be adjustably contained in brush carrier (4), And by spring element (7) towards current collector (5) direction apply power, it is characterised in that Look up in the regulation side of described brush (3), along with reach limit abrasion stroke, described Contact area between brush (3) and described current collector (5) changes, and wherein can pass through Measured value detects the abrasion stroke reaching to limit.

Equipment the most according to claim 1, it is characterised in that at least two brush (3) There is different greatest wear strokes.

Equipment the most according to claim 2, it is characterised in that described motor has many The individual brush pair respectively with two described brushes, the brush (3) of a brush pair is relative to it The brush (3) of his brush pair has the abrasion stroke of reduction.

Equipment the most as claimed in any of claims 1 to 3, it is characterised in that Described brush carrier (4) is provided for the amount of feeding of described brush (3) is restricted to energy The stop device of the size set, wherein can measure and reach the maximum amount of feeding.

Equipment the most according to claim 1, it is characterised in that described measured value is institute State the electrical characteristic values of motor (2).

Equipment the most according to claim 1, it is characterised in that described spring element (7) Regulation campaign be restricted.

Equipment the most according to claim 1, it is characterised in that described brush (3) Regulation motion is restricted.

Equipment the most according to claim 1, it is characterised in that described brush (3) has Having the abrasion section (13) of constant cross-sectional area, the most described abrasion section is base segment (12), Described base segment (12) has the cross-sectional area different from described abrasion section (13).

Equipment the most according to claim 8, it is characterised in that described base segment (12) There is the cross-sectional area less than described abrasion section (13).

10. a motor, it is characterised in that described motor has according to claim 1 to 9 Equipment described in middle any one.

11. motors according to claim 10, it is characterised in that described motor is to use Starting motor in internal combustion engine.

12. 1 kinds for operating equipment as claimed in any of claims 1 to 9 Method, it is characterised in that detected the abrasion stroke reaching to limit by measured value, and Show a signal.

13. methods according to claim 12, it is characterised in that monitoring motor (2) At least one electrical characteristic values, and infer from the change of this feature value and reach greatest wear Stroke.

14. 1 kinds of regulations or control equipment, for performing according to claim 12 or 13 Described method.