Hand-held power tool and production method for a hand-held power tool

Abstract

The hand-held power tool (1) includes a transmission housing (24) for receiving a transmission (23), a motor housing (25) for receiving a motor (5), a bearing plate (28) arranged between the transmission housing (24) and the motor housing (25) for mounting a shaft (21) of the motor (5), at least one first screw (32) which fastens the bearing plate (28) to the motor housing (25), wherein the first screw (32) is not in engagement with the transmission housing (24), and at least one second screw (33) which fastens the transmission housing (24) to the bearing plate (28), wherein the second screw (33) is not in engagement with the motor housing (25).

Claims

1-15. (canceled)

16: A hand-held power tool comprising: a transmission housing for receiving a transmission; a motor housing for receiving a motor; a bearing plate arranged between the transmission housing and the motor housing for mounting a shaft of the motor; at least one first screw fastening the bearing plate to the motor housing, the first screw not being in engagement with the transmission housing; and at least one second screw fastening the transmission housing to the bearing plate, the second screw not being in engagement with the motor housing.

17: The hand-held power tool as recited in claim 16 further comprising at least one third screw fastening the transmission housing, the bearing plate and the motor housing to one another.

18: The hand-held power tool as recited in claim 16 wherein the motor housing has at least one dome for engagement of a thread of the at least one first screw or of at least one third screw.

19: The hand-held power tool as recited in claim 18 wherein the bearing plate has at least one bore for receiving the at least one dome of the motor housing.

20: The hand-held power tool as recited in claim 16 wherein the at least one first screw or at least one third screw is a self-tapping screw.

21: The hand-held power tool as recited in claim 16 wherein the bearing plate has at least one threaded bore for screwing in the at least one second screw.

22: The hand-held power tool as recited in claim 16 wherein the bearing plate has at least one dome for receiving the at least one second screw.

23: The hand-held power tool as recited in claim 16 wherein an axis of rotation of the motor shaft encloses an angle with an axis of rotation of the drive shaft.

24: The hand-held power tool as recited in claim 23 wherein the at least one first screw is arranged on a plane of symmetry of the hand-held power tool running through the axis of rotation of the drive shaft and the axis of rotation of the motor shaft.

25: A method for producing a hand-held power tool having a transmission housing for receiving a transmission, a motor housing for receiving a motor, a bearing plate (28) for mounting a shaft of the motor and at least one first and one second screw, the method comprising the steps of: fastening the bearing plate to the motor housing with the at least one first screw; providing the transmission housing; and fastening the transmission housing to the bearing plate with the at least one second screw, the second screw not being in engagement with the motor housing.

26: The method as recited in claim 25 further comprising the step of fastening the transmission housing, the bearing plate and the motor housing to one another with at least one third screw.

27: The method as recited in claim 25 wherein, when fastening the bearing plate to the motor housing with the at least one first screw, or when fastening the transmission housing the bearing plate and the motor housing to one another with at least one third screw, at least one dome of the motor housing is introduced into at least one bore of the bearing plate.

28: The method as recited in claim 25 wherein the at least one first screw or at least one third screw is screwed into the motor housing in a self-tapping manner.

29: The method as recited in claim 25 wherein when fastening the transmission housing to the bearing plate with the at least one second screw, at least one dome of the bearing plate is introduced into a bore of the transmission housing.

30: The method as recited in claim 25 wherein when fastening the transmission housing to the bearing plate with the at least one second screw, the at least one second screw is screwed into a threaded bore of the bearing plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The following description explains the invention with reference to exemplary embodiments and figures, in which:

[0052] FIG. 1 shows a schematic view of a hammer drill;

[0053] FIG. 2 shows a schematic exploded view of a transmission housing, a bearing plate and a motor housing of the hammer drill from FIG. 1;

[0054] FIG. 3 shows a detail view of the bearing plate from FIG. 2;

[0055] FIG. 4 shows a detail view of the transmission housing from FIG. 2; and

[0056] FIG. 5 shows a flow diagram of a method for producing the hammer drill from FIG. 1.

[0057] Identical or functionally identical elements are indicated by identical reference signs in the figures, unless stated otherwise.

DETAILED DESCRIPTION

[0058] FIG. 1 schematically shows a hammer drill 1 as an example of a hand-held power tool. The hammer drill 1 has a tool fitting 2, into which a shaft end 3 of a tool, for example of a drill bit 4, can be inserted. A motor 5, which drives an impact mechanism 6 and a drive shaft 7, forms a primary drive of the hammer drill 1. A battery 8 or a power cord supplies the motor 5 with power. A user can hold and guide the hammer drill 1 by means of a handle 9. Furthermore, the user can put the hammer drill 1 into operation by means of a main switch 10. As a result of the main switch 10 being actuated, the drive shaft 7 coupled to the tool fitting 2 sets the tool fitting 2 into rotation about a working axis 11. As a result, the tool 4 is rotated about the working axis 11. During operation, in addition to the rotation about the working axis 11, the hammer drill 1 can strike the tool 4 into a substrate in a striking direction 12 along the working axis 11. In one exemplary embodiment, the hammer drill 1 has a mode selector switch, by way of which the tool fitting 2 can be uncoupled from the drive shaft 7 such that a purely striking mode of the hammer drill 1 is possible.

[0059] The impact mechanism 6 is a pneumatic impact mechanism. An exciter piston 13 and an impact piston 14 are guided in movement along the working axis 11 in a guide tube 15 in the impact mechanism 6. The exciter piston 13 is coupled to the motor 5 via an eccentric 16 and forced to carry out a periodic, linear movement. A connecting rod 17 connects the eccentric 16 to the exciter piston 13. A pneumatic spring 18 formed by a pneumatic chamber between the exciter piston 13 and the impact piston 14 couples a movement of the impact piston 14 to the movement of the exciter piston 13. The impact piston 14 strikes an anvil 19, which transfers the impact to the drill bit 4.

[0060] The drive shaft 7 connected to the tool fitting 2 is coupled to the motor 5, in particular to a shaft 21 of the motor 5, via gearwheels 20.

[0061] In the example shown in FIG. 1, the shaft 21 driven by the motor 5 is arranged at a right angle to the drive shaft 7. In particular, an axis of rotation 22 of the motor shaft 21 is arranged at a right angle to the working axis 11, which corresponds to the axis of rotation of the drive shaft 7.

[0062] The drive shaft 7, the impact mechanism 6 and further drive components, such as the eccentric 16, the connecting rod 17 and the gearwheels 20, are part of a transmission 23 (drive unit) of the hammer drill 1. The transmission 23 is received in a transmission housing 24 (FIG. 2). The transmission housing 24 is in particular made of metal.

[0063] The motor 5 is accommodated in a motor housing 25 which is open at the top (FIG. 2). The motor housing 25 is made of plastic. It is manufactured in an injection-molding process, for example.

[0064] The motor housing 25 forms part of an outer housing 26 (FIG. 1) of the hammer drill 1. In addition to the motor housing 25, the outer housing 26 of the hammer drill 1 also comprises a plastic shell 27 (FIG. 1) which surrounds the metallic transmission housing 24 (FIG. 2). The outer housing 26 can also comprise further elements, such as the handle 9, for example.

[0065] As shown in FIG. 2, the hammer drill 1 also comprises a bearing plate 28 for mounting the shaft 21 of the motor 5 (or a rotor of the motor 5). The bearing plate 28 is arranged between the transmission housing 24 and the motor housing 25.

[0066] FIG. 3 shows an enlarged view of the bearing plate 28. The bearing plate 28 has a lower side 29 facing the motor housing 25 in the assembled state of the hammer drill 1 and an upper side 30 facing the transmission housing 24. In addition, the bearing plate 28 has a central through-bore 31 through which the shaft 21 (FIGS. 1 and 2) of the motor 5 is guided.

[0067] The bearing plate 28 is fastened to the motor housing 25 with at least one first screw 32 (FIG. 2). In the example of FIG. 2, the bearing plate 28 is fastened to the motor housing 25 with precisely one first screw 32.

[0068] The transmission housing 24 is fastened to the bearing plate 28 with at least one second screw 33. In the example of FIG. 2, the transmission housing 24 is fastened to the bearing plate 28 with two second screws 33.

[0069] In addition, the transmission housing 24, the bearing plate 28 and the motor housing 25 are fastened to one another with at least one third screw 34 (two third screws 34 in the example of FIG. 2).

[0070] To fasten the first screw 32 and the two third screws 34 to the motor housing 25, the motor housing 25 has three domes (screw domes) 35, 36. The three domes 35, 36 are, for example, manufactured integrally with the motor housing 25 in an injection-molding process. Each of the three domes 35, 36 has an upwardly open pilot bore 37 (blind hole). The pilot bores 37 of the domes 35, 36 of the motor housing 25 are used for better insertion of the first screw 32 and the third screws 34.

[0071] To attach the bearing plate 28 to the motor housing 25 and to the transmission housing 24, the bearing plate 28 has a first bore 38, two second bores 39 and two third bores 40 (FIG. 3).

[0072] The first bore 38 of the bearing plate 28 is threadless and serves to receive the dome 35 of the motor housing 25 and to fasten the first screw 32.

[0073] The second bores 39 of the bearing plate 28 each have a thread 41 and are used to fasten the second screws 33. In addition, the second bores 39 have domes 42 protruding from the upper side 30 of the bearing plate 28 for positioning the transmission housing 24.

[0074] The third bores 40 are threadless and serve to receive the domes 36 of the motor housing 25 and to fasten the third screws 34.

[0075] In the example shown, all of the bores 38, 39, 40 of the bearing plate 28 are through-bores which go through from the lower side 29 to the upper side 30 of the bearing plate 28. In other examples, the second bores 39 can also be blind holes which are open to the upper side 30 of the bearing plate 28 facing the transmission housing 24 and are closed to the lower side 29 of the bearing plate 28 facing the motor housing 25.

[0076] The first bore 38 is arranged centrally on the bearing plate 28, that is to say on an axis of symmetry 43 of the bearing plate 28. The axis of symmetry 43 of the bearing plate 28 is parallel to the working axis 11 in the assembled state of the hammer drill 1. The two second bores 39 and the two third bores 40 are each arranged laterally from the axis of symmetry 43 and symmetrically to the axis of symmetry 43.

[0077] Each of the first and third screws 32, 34 has a screw head 44 and a shaft 45 with a thread 46. The first screw 32 and the third screws 34 are in particular self-tapping screws which, by means of their thread 46, can be tapped/imprinted into the plastic material of the motor housing 25, in particular the domes 35, 36 of the motor housing 25. The first screw 32 and the third screw 34 are, for example, REMFORM screws.

[0078] Each of the second screws 33 has a screw head 47 and a shaft 48 with a thread 49. The second screws 33 are screwed into the threaded bores 39 of the bearing plate 28, so that the thread 49 of the screws 33 comes into engagement with the mating thread 41 of the bearing plate 28. The screws 33 are, for example, metric screws. The shaft 48 of the screws 33 is in particular shorter than the shaft 45 of the screws 32, 34. This ensures that a lower end 50 (FIG. 2) of the screws 33 does not protrude from the lower side 29 (FIG. 3) of the bearing plate 28. For example, the lower end 50 of the screws 33 is flush with the lower side 29 of the bearing plate 28.

[0079] To attach the transmission housing 24 to the bearing plate 28 by means of the second screws 33 and to the motor housing 25 by means of the third screws 34, the transmission housing 24 has four through-bores 51, 52 (FIG. 2). FIG. 4 shows the transmission housing 24 from below, that is to say from a side 53 of the transmission housing 24 facing the bearing plate 28. The through-bores 51, 52 extend from the side 53 of the transmission housing 24 to a side 54 of the transmission housing 24 opposite the side 53. The two sides 53 and 54 of the transmission housing 24 are in particular sides of a mounting flange 55 of the transmission housing 24.

[0080] In the assembled state of the transmission housing 24, the bearing plate 28 and the motor housing 25, the bearing plate 28 is arranged on the motor housing 25 in such a way that the dome 35 of the motor housing 25 is inserted into the through-bore 38 of the bearing plate 28 and the domes 36 of the motor housing 25 are inserted into the through-bores 40 of the bearing plate 28. In addition, the self-tapping first screw 32 is tapped into the dome 35 of the motor housing 25 received in the bore 38 of the bearing plate 28. The first screw 32 thus connects the bearing plate 28 to the motor housing 25. In particular, the screw head 44 engages behind the upper side 30 (FIG. 3) of the bearing plate 28. The first screw 32 is in particular not in engagement with the transmission housing 24.

[0081] Furthermore, in the assembled state of the transmission housing 24, the bearing plate 28 and the motor housing 25, the self-tapping third screws 34 are guided through the bores 52 of the transmission housing 24 and tapped into the domes 36 of the motor housing 25 received in the third bores 40 of the bearing plate 28. The third screws 34 thus connect the transmission housing 24, the bearing plate 28 and the motor housing 25. The screw head 44 of the third screws 34 engages in particular behind the upper side 54 (FIG. 2) of the transmission housing 24.

[0082] In addition, in the assembled state of the transmission housing 24, the bearing plate 28 and the motor housing 25, the domes 39 of the bearing plate 28 are inserted into the bores 51 of the transmission housing 24 and the second screws 33 (thread 49) are screwed into the mating thread 41 of the domes 39 of the bearing plate 28. The second screws 33 thus connect the transmission housing 24 to the bearing plate 28. The screw head 47 of the second screws 33 engages in particular behind the upper side 54 (FIG. 2) of the transmission housing 24. The lower end 50 of the screws 33, which is opposite the screw head 47, does not protrude from the bottom of the bearing plate 28.

[0083] Since the second screws 33 are anchored in the bearing plate 28 and not in the motor housing 25, no screw counterparts, such as domes similar to the domes 35, 36, are required for the second screws 33 in the motor housing 25. In this way, space can be saved in a front region 55 (FIGS. 1 and 2) of the motor housing 25. Thus, the front region 55 of the motor housing 25 can be made slimmer. Thus, the hammer drill 1 can be better held and guided by a user who holds the hammer drill 1 with one hand on the handle 9 (FIG. 1) and with the other hand on the front region 55 of the motor housing 25.

[0084] A method for producing the hand-held power tool 1 (the hammer drill 1) is described below with reference to FIG. 5. In particular, the method is used to fasten the transmission housing 24, the bearing plate 28 and the motor housing 25 to one another.

[0085] In a first step S1 of the method, the bearing plate 28 is arranged on the motor housing 25 in such a way that the domes 35, 36 of the motor housing 25 are inserted into the bores 38, 40 of the bearing plate 28.

[0086] In a second step S2 of the method, the bearing plate 28 is screwed to the motor housing 25 by means of the first screw 32. Here, the first screw 32 is screwed in a self-tapping manner into the dome 35 of the motor housing 25 received in the bore 38 of the bearing plate 28.

[0087] In a third step S3 of the method, the transmission housing 24 is provided.

[0088] In a fourth step S4 of the method, the transmission housing 24 is fastened to the bearing plate 28 by means of the two second screws 33. First, the two domes 42 of the bearing plate 28 are here introduced into the bores 51 of the transmission housing 24. Then the two second screws 33 are screwed into the threaded bores 39 of the bearing plate 28. The second screws connect, in particular, the transmission housing 24 and the bearing plate 28 without, however, coming into engagement with the motor housing 25.

[0089] In a fifth step S5 of the method, the transmission housing 24, the bearing plate 28 and the motor housing 25 are connected to one another by means of the two third screws 34. Here, the third screws 34 are screwed in a self-tapping manner into the domes 36 of the motor housing 25 received in the bores 40 of the bearing plate 28.

[0090] The screwing of the second screws 33 into the threaded bores 39 of the bearing plate 28 in step S4 can also be carried out after step S5.

LIST OF REFERENCE SIGNS

[0091] 1 Hand-held power tool [0092] 2 Tool fitting [0093] 3 Shaft end [0094] 4 Tool [0095] 5 Motor [0096] 6 Impact mechanism [0097] 7 Drive shaft [0098] 8 Battery [0099] 9 Handle [0100] 10 Main switch [0101] 11 Working axis [0102] 12 Striking direction [0103] 13 Exciter piston [0104] 14 Impact piston [0105] 15 Guide tube [0106] 16 Eccentric [0107] 17 Connecting rod [0108] 18 Pneumatic spring [0109] 19 Anvil [0110] 20 Gearwheel [0111] 21 Motor shaft [0112] 22 Axis of rotation [0113] 23 Transmission (drive unit) [0114] 24 Transmission housing [0115] 25 Motor housing [0116] 26 Outer Housing [0117] 27 Shell [0118] 28 Bearing plate [0119] 29 Lower side [0120] 30 Upper side [0121] 31 Through-bore [0122] 32 First screw [0123] 33 Second screw [0124] 34 Third screw [0125] 35 Dome [0126] 36 Dome [0127] 37 Pilot bore [0128] 38 First bore [0129] 39 Second bore [0130] 40 Third bore [0131] 41 Thread [0132] 42 Dome [0133] 43 Axis of symmetry [0134] 44 Screw head [0135] 45 Shaft [0136] 46 Thread [0137] 47 Screw head [0138] 48 Shaft [0139] 49 Thread [0140] 50 End [0141] 51 Through-bore [0142] 52 Through-bore [0143] 53 Side [0144] 54 Side [0145] 55 Mounting flange [0146] Angle [0147] S1-S5 Method steps