Carbon brush holder device

Abstract

A motor (2) includes a carbon brush holder device (16) for reversing the rotating direction of the motor (2) and which has a brush holder (18) which is rotatable relative to the stator (8) of the motor (2) in clockwise running position and counterclockwise running position, two carbon brush guides which electrically connected to the stator (8) in both running positions by a switching arrangement (45) and provided at the brush holder (18), with the switching arrangement (45) having stator-side switching contact means and brush-side switching contact means which produce different contacts in the clockwise running position and the counterclockwise running position for reversing the polarity of the motor (2), and with the switching contact means are being encapsulated relative to the rest of the carbon brush holder device (16).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings show:

FIG. 1: a side view of a motor with a carbon brush holder device according to the invention;

FIG. 2: a top view of the carbon brush holder device in direction II referring to FIG. 1; and

FIG. 3: a top view, considered in direction III in FIG. 1, of a switch of the carbon brush holder device without the motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:

FIG. 1 shows a motor 2 in the form of a universal motor for a hand-held electric power tool which drives a tool holder, not shown, in a first rotating direction D1 or a second rotating direction D2 by means of a motor shaft 4. The motor 2 has a stator 8 and a rotor 10 both located in a stator housing 6. A stator winding, not shown in more detail, is connected by two electric stator connections 12 to a switch 14 in the form of a commercially available lug switch that is fastened to the stator housing 6.

A carbon brush holder device, designated in its entirety by 16, is provided at one end of the stator housing 6. This carbon brush holder device has a brush holder 18 with an annular base body 20 which is held so as to be rotatable in a rotational direction S (see FIG. 2) on bearing pins 22 which are fixed with respect to the housing and which support a bearing block 24. The bearing block 24 serves to support the motor shaft 4 at one end at which a commutator 26 of the motor 2 is arranged.

As can be seen particularly from FIG. 2, the brush holder 18 has two carbon brush guides 28 for receiving and guiding carbon brush brushes, not shown in more detail, and a handle 30 which projects radially from the base body 20. This handle 30 serves to displace the brush holder 18 in rotational direction S between a clockwise running position shown in FIG. 2 and a counterclockwise running position which is indicated by dash-dot lines. The handle 30 can be actuated from outside a device housing, not shown.

The handle 30 serves at the same time as an actuating element for the switch 14. For this purpose, the handle 30 is coupled with a switching member 32 of the switch 14 and which is formed by a switch lug. The switching member 32 projects from a switch housing 34 of the switch 14 and partially engages around the handle 30. Alternatively, the handle 30 can also have a receptacle for the switching member 32. In this case, the switching member 32 is coupled with the handle 30 and, by rotational the latter, can be moved into two switching positions corresponding to the clockwise running position and the counterclockwise running position of the brush holder 18.

Further, locking means, designated in their entirety by 36, is provided between the stator housing 6 and the brush holder 18. The locking means 36 reliably holds the carbon brush guides 28 in the respective selected running position that is predetermined in such a way that an optimal commutation is achieved in the clockwise running position and counterclockwise running position. For this purpose, the locking means 36 has, for example, a plurality of recesses 38 which are incorporated in the brush holder 18 and which cooperate in both the counterclockwise running position and the clockwise running position with correspondingly positioned locking catches 40 of two spring elements 42 which are held at the stator housing 6.

When the brush holder 18 is fixed in one of the two running positions, one of the two switching positions of the switching member 32 and switch 14, respectively, is also secured at the same time.

It can also be seen that the switch 14 is electrically connected to the carbon brush guides 28 in each instance by an electric wire conductor 44 so that the switch 14 can be positioned virtually anywhere in relation to the brush holder 18.

The operation of the switch 14 is illustrated with reference to FIG. 3. As can be seen from this drawing, a switching arrangement 45, shown schematically, is received in the switch housing 34 so as to be almost completely enclosed relative to the outside. The switch housing 34 has recesses (not shown) only in the areas in which the electric stator connections 12, the conductors 44, and the switching member 32 enter and exit, respectively. Appropriate structural steps or additional sealing means can be provided at these recesses to improve the sealing of the switch housing 34 from the outside.

The switching arrangement 45 has first stator-side switching contact means 46a and second stator-side switching contact means 46b which are connected to the electric stator connections 12, and first brush-side switching contact means 48a and second brush-side switching contact means 48b which are connected to the conductors 44. In the switching position shown in the drawing, which corresponds to the clockwise running position of the brush holder 18, the first stator-side switching contact means 46a is connected to the first brush-side switching contact means 48a, and the second stator-side switching contact means 46b is connected to the second brush-side switching contact means 48b.

In the switching position shown with dash-dot lines and corresponding to the counterclockwise running position of the brush holder 18, the first stator-side switching contact means 46a is connected to the second brush-side switching contact means 48b, and the second stator-side switching contact means 46b is connected to the first brush-side switching contact means 48a.

This different commutation in the two switching positions results in a reversal of polarity of the motor and, therefore, in a respective change in the rotational direction of the motor when the brush holder 18 is pivoted between the two running positions.

Though the present invention was shown and described with references to the preferred embodiment, such is merely illustrative of the present invention and is not to be construed as a limitation thereof and various modifications of the present invention will be apparent to those skilled in the art. It is therefore not intended that the present invention be limited to the disclosed embodiment or details thereof, and the present invention includes all variations and/or alternative embodiments within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. An electric motor (2), comprising a stator (8); and a carbon brush holder (16) for reversing a rotational-direction of the motor (2) and including a brush holder (18) rotatable relative to the stator (8) in clockwise running position and counterclockwise running position, two carbon brush guides (28) provided at the brush holder (18), and a switching arrangement (45) for electrically connecting the two carbon brush guides to the stator (8) in the clockwise and counterclockwise running positions, the switching arrangement (45) being adjustable by the brush holder (18) and having stator-side switching contact means (46a, 46b) and brush-side switching contact means (48a, 48b) which produce different contacts in the clockwise running position and the counterclockwise running position for reversing polarity of the motor (2), the switching contact means (46a, 46b; 48a, 48b) being encapsulated relative to the carbon brush holder device (16).

2. A motor according to claim 1, further comprising a switch (14) actuatable by the brush holder (18) and having a housing (34) in which the switching means (46a, 46b; 48a, 48b) is received.

3. A motor according to claim 2, wherein the switch (14) has a switching member (32) movable into two switching positions by the brush holder (18).

4. A motor according to claim 3, wherein the switch (14) is formed as a lug switch, and the switching member (32) is formed by the switching lug.

5. A motor according to claim 3, wherein the brush holder (18) has an actuation element for actuating the switching member (32).

6. A motor according to claim 5, wherein the actuation element is formed by a handle (30) of the brush holder (18) with which the brush holder (18) can be adjusted between the running positions.

7. A motor according to claim 1, wherein electric connections are provided between the brush-side switching contact means (48a, 48b) and the carbon brush guides (28) by conductors (44).

8. A motor according to claim 2, wherein the switch (14) is held at the stator (8).