WO1993005561A1

WO1993005561A1 - Hand-held tool with an electric motor

Info

Publication number: WO1993005561A1
Application number: PCT/DE1992/000713
Authority: WO
Inventors: Alfred Odendahl; Ernst Kränzler; Thomas Fuchs
Original assignee: Robert Bosch Gmbh
Priority date: 1991-09-06
Filing date: 1992-08-27
Publication date: 1993-03-18
Also published as: DE4129720A1

Abstract

An electric tool, especially a hand-held tool (1) comprises a housing consisting especially of half-shells (49), and an electric motor (2) in the form of a reversible collector motor with a motor shaft (5) bearing a rotor (3). A bearing (9) fitted on the end of the motor shaft (5) at the end nearest the collector is arranged on the one hand in the half-shell (49) and on the other hand is surrounded by a bearing bridge (21) which can be electrically connected to a power supply and a stator (11) and can take the brush holder (31) for carbon brushes. Said electric tool is designed for easier and more accurate assembly in such a way that electric plug components (23, 25, 27, 29) of the bearing bridge (21) can be inserted directly into socket components (13, 15, 17, 19) in the stator (11) and their mutual positioning is determined in that an insulating plate (45) passing through at least one slot (43) in the bearing bridge (21) and guided to slide therein can overlap the motor shaft (5) between the collector (7) and the bearing (9) and hence secure the rotor (3) and the bearing bridge (21) axially in relation to each other, especially in a prefitting position for location in the half-shell (49).

Description

Hand tool with an electric motor

State of the art

The invention is based on a hand-held machine tool according to the preamble of claim 1.

Their essential generic feature is a housing which can be assembled from half-shells and into which the electric motor is at least partially pre-assembled and inserted transversely to the axis. In contrast to this, in the case of the pot design, the electric motor is preassembled in the axial direction and inserted into the preferably pot-shaped housing which can be screwed onto the cover.

A generic hand-held power tool is known from US 4,638,196. Its multi-part housing, formed from half-shells, contains a bearing block, preferably made of insulating plastic, and accommodates a bearing bridge, which forms a preassembled assembly with brush holders and brushes, which are fastened with fastenings on the pedestal in the half-shell can be converted into its operative position. On one side, the brushes are electrically connected to a power supply cable via plug contacts of the bearing bridge and via a switch, and on the other side they can be coupled to the stator via further electrical plug contacts, with a separate, electrical reversing switch, ie for right Counterclockwise rotation, via separate cables or plug contacts with the bearing bridge can be connected trically.

For all handheld power tools with an electric motor drive, it is a requirement in Germany that an insulation shield must be arranged on the rotor shaft between the collector and the bearing in order to create a barrier against leakage currents from the collector to the bearing. For this purpose, a perforated disc made of insulating plastic is slid onto the rotor shaft before assembly of the bearing and the bearing is then pressed on. In the generic machine tool, the housing or the bearing bridge is designed such that a fixed insulation shield is arranged near the bearing seat in such a way that it encompasses the rotor shaft between the bearing and the collector in a U-shape.

The known hand-held power tool has the disadvantage that, in the final assembly of the bearing bridge, a separate reversing switch and the rotor in the half-shell, the outlay in terms of cabling and assembly is high. The configuration of the bearing bracket with a fixed insulation shield, which reduces the assembly effort slightly compared to the known prior art, allows only a certain type of assembly of the known handheld power tool, it being impossible, for example, to first assemble the bearing bracket with the stator and then the one with the Guide the pre-assembled bearing through the stator and anchor it in the bearing bracket. Here the insulation shield, which is advantageous per se, forms an impassable obstacle to assembly: the possible angle of inclination of the rotor in the stator during assembly is too small to allow passage of the collector-side rotor shaft end together with the bearing via the insulation shield.

Advantages of the invention

The hand tool according to the invention with the characteristic Features of claim 1 have the advantage over the prior art that a bearing bridge with an integrated reversing switch can be fixed outside the housing on the stator, and that the rotor can be pre-assembled in the bearing bridge through the stator. In addition, there is a reduced volume of the bearing bridge, short, robust cable routes between the direction of rotation and reversing switch and the brushes and a smaller number of parts. A particular advantage is that the assembly position mentioned can be fixed particularly precisely and securely in the housing by means of the laterally insertable insulation shield.

drawing

An embodiment of the invention is explained with reference to the following description with accompanying drawings. The drawing shows in FIG. 1 an exploded view of the drive area of a hand tool according to the invention, FIG. 2 shows a side view of the preassembled motor parts in mounting position over a housing half-shell and FIG. 3 shows an embodiment of the bearing bracket of the hand tool according to the invention.

Description of the embodiment

The hand-held power tool 1 partially shown in FIG. 1 shows a rotor 3, on the rotor shaft 5 of which a collector 7 and at a distance adjacent to it sits a firmly mounted bearing 9 designed as a ball bearing. At an axial distance from this, concentrically to the rotor 3, there is shown a schematically illustrated stator 11, which carries socket elements 13, 15, 17, 19 on its side facing away from the rotor 3. A bearing bracket 21 is shown at an axial distance from these. On its side facing the stator 11, the bearing bridge 21 carries plug elements 23, 25, 27, 29, which fit into the socket elements 13, 15, 17, 19 of the stator 11. On opposite sides transverse to the longitudinal axis of the rotor 3, the bearing bridge 21 carries brush holders 31, 33 for receiving carbon brushes, not shown. A hollow socket 35 sits essentially parallel to the brush holders 31, 33 on the underside of the bearing bridge 21. Inside the hollow socket 35, conductor rails (not shown) in the form of extensions of the plug elements 23, 25, 27, 29 are exposed in some areas , without electrical isolation. This is supported by a switching disk 37 with switching contacts (not shown) and a switching cover 39 which are in engagement with a switching lever 41 which can be pivoted about an axis 57. With this, a change in the direction of rotation of the rotor 3 is achieved in each end position. The switching disk 37, the cover 39 and the switch lever 41 are detachably seated in the hollow connector 35.

The bearing bridge 21 has a slot 43 which extends transversely to the axis of the rotor 3 and in which an insulation shield 45 can be displaced in a guided manner. Transversely to the axial direction of the side facing away from the rotor 3, a downwardly open, semicircular bearing shell 47 is formed in the bearing bridge 21, which forms half of the seat for the outer ring of the bearing 9 of the rotor 3. The other side of the seat is formed by an upwardly open, semicircular bearing shell 48 of a bearing block 51 seated in a lower half shell 49 of the housing, into which the rotor 3, the stator 11 and the bearing bracket 21 can be inserted completely pre-assembled.

The slot 43 in the bearing bridge 21 and the insulation plate 45 are dimensioned such that in the assembled position of the rotor 3 to the bearing bridge 21 the space between the collector 7 and the ball bearing 9 is encompassed by the insulation plate 45 and thus the axial position of the rotor 3 is secured.

In the lower half-shell 49 is together with the aforementioned, preassembled parts an on and off switch 53 can be used, on which a cover plate 55 is supported with an axis 57, which form a pivot bearing for the switch lever 41.

The electric motor 2 is mounted in the following way: The bearing bridge 21 is coupled to the socket elements 23, 25, 27, 29 of the stator 11 via the plug elements 13, 15, 17, 19. With this, their mutual position is fixed.

Subsequently, the rotor 3 preassembled with the bearing 9 is pushed through the stator 11 into its operative position, so that the bearing 9 is seated in the bearing seat of the bearing bracket 21, namely in the bearing shell 47. This pre-assembly position is fixed by inserting the end shield 45 into the slot 43 between the collector 7 and the bearing 9.

The pre-assembled parts are then inserted into the half-shell 49, so that the lower region of the outer ring of the bearing 9 is seated in the bearing shell 48. Then, through unspecified through holes in the bearing bridge 21, the latter is connected to the bearing block 51, for example screwed. The displaceable insulation shield 45 overlaps the fixed counter-insulation shield 46 and adheres to it with a non-specified latching connection in a force-locking or positive manner.

FIG. 2 shows a side view of the embodiment shown in FIG. 1 with slightly changed proportions as a pre-assembled unit consisting of stator 11, rotor 3 and bearing bracket 21, the coupling of the insulation shield 45 to the counter-insulation shield 46 being clearly visible .

The lower half shell 49 of the housing is shown in its assignment to the preassembled unit. The bearing block 51 is in one piece with the fixed counter-insulation shield 46 for axial securing of the rotor 3 connected. The counter insulation shield 46 can be partially overlapped by the displaceable insulation shield 45. In the end position, the two insulation slides 45, 46 hold on to one another in a non-positive or positive manner, in particular latching.

In Figure 3, compared to Figure 1 rotated by about 180 °, the inner, electrically conductive parts of the bearing bracket 21, the busbars 63 to 73, are shown in perspective. The busbars 63 to 73, which can be punched out of sheet metal and end in plug elements 23, 25, 27, 29, are hard on the surface. This makes it possible to arrange an integrated rotational direction switch 34 with a particularly high number of possible switching cycles. In addition, the busbars of the bearing bridge 21 provide skeletal support and ensure their dimensional stability.

The busbars 63, 69 carry coil-like elements 75 to suppress or to minimize sparking between the carbon brushes (not shown) and the collector 7.

In an embodiment of the bearing bracket, not shown, the busbars carry further electrical or electronic components suitable for power control or for interference suppression.

In a further embodiment of the invention, which is not shown in pot design, a one-piece bearing bridge is provided which contains the complete seat for the collector-side bearing. In front of the seat, slots are machined into the bearing bridge, in particular on angularly opposite sides, in each of which an insulation shield is slidably guided. The insulation shields can grip around the rotor shaft in the installed position between the collector and the bearing and, moreover, can hold onto one another in a captive manner. The rotor is thus axially secured to the bearing bridge or the stator.

Claims

Expectations

1. Power tool, in particular hand tool (1), with a housing, in particular consisting of half-shells (49), with an electric motor (2) designed as a collector motor that can be reversed in the direction of rotation, with a motor shaft (5) carrying a rotor (3), a bearing (9) seated at the collector-side end of the motor shaft (5) partly sits in a bearing block (51) in the housing, in particular the half-shell (49), partly in a bearing bridge (21), which can be electrically connected to a power supply and a stator (11) and contains the brush holder (31) for carbon brushes, characterized in that electrical plug elements (23, 25, 27, 29) of the bearing bridge (21) directly in socket elements (13 , 15, 17, 19) can be plugged into the stator (11), as a result of which the position of the bearing bridge (21) and stator (11) in relation to one another is determined such that at least one is inserted through at least one slot (43) in the bearing bridge (21) pushed insulation shield (45) Motor shaft (5) grips between the collector (7) and bearing (9) in a fork-like manner and thus holds the rotor (3) and bearing bracket (21) axially to one another, in particular in a pre-assembly position intended for positioning in the half-shell (49).

2. Power tool according to claim 2, characterized in that the insulation shield (45) fixes the rotor (3) with respect to the stator (11) in the preassembly location.

3. Power tool according to claim 2, characterized in that the rotor shaft (5) overlapping insulation shield (45) on a, in particular in one piece with the bearing block (51) connected to the counter piece (46) when it on the bearing block ( 51) is positioned and thus secures the rotor (3), the bearing bridge (21), the stator (11) and the bearing block (51) and thus the half-shell (49) to one another.

4. Power tool according to claim 3, characterized in that the counterpart is a, in particular integrally molded, counter-Isolati¬ onsschild (46) and that the insulation shield (45) and the counter-insulation shield (46) in the final assembly position of Electric motor (2) in the half-shell (49) are captively locked together.

5. Power tool according to one of the preceding claims, characterized in that the bearing bridge (21) is designed in one or more pieces aus¬.

6. Power tool according to one of the preceding claims, characterized in that the bearing block (51) on the half-shell (49) is zen¬ releasably attached.

7. Power tool according to claim 6, characterized in that the bearing block (51) is integrally connected to the bearing bridge (21), the counter-insulation shield (46) and the insulation shield (45) inserted into a slot, from different directions to each other are movable and can be locked together.

8. Power tool according to one of the preceding claims, in particular according to claim 7, characterized in that the counter insulation shield (46) in the bearing block (51) is inserted into a slot.

9. Power tool according to one of the preceding claims, characterized in that for reversing the direction of rotation in the Lager¬ bridge (21) integrated, by means of a rotatable in the bearing bridge (21) arranged reversing direction switch (34) busbars (63, 65, 67th , 69, 71, 73, 75) can be brought into contact with one another alternately.

10. Power tool according to claim 9, characterized in that in the bearing bridge (21) an electrically conductive switching element in the form of a switching disc (37) on the busbars (63, 65, 67, 69, 71, 73, 75) and between two Switching positions is held switchable.

11. Power tool according to one of the preceding claims, characterized in that the bearing bridge (21) contains electrical components, in particular chokes (75), for interference suppression.

12. Power tool according to one of the preceding claims, characterized in that the busbars (63, 65, 67, 69, 71, 73, 75) are preferably made of sheet metal and spatially curved stamped and bent parts which are injection molded with plastic in the Bearing bridge (21) are formed and the contour piercing - form the connector elements (23, 25, 27, 29).