GB2414049A

GB2414049A - Bearing device and ventilating device

Info

Publication number: GB2414049A
Application number: GB0509614A
Authority: GB
Inventors: Karl Frauhammer; Heinz Schnerring; Willy Braun; Axel Kuhnle
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2004-05-15
Filing date: 2005-05-11
Publication date: 2005-11-16
Anticipated expiration: 2025-05-11
Also published as: US20050281687A1; CN1696526A; GB2414049B; DE102004024287A1; GB0509614D0

Abstract

A bearing device comprises a fastening element 10 for rotatably mounting a drive shaft 12 of a hand-tool appliance, wherein the fastening element has heat-conducting means 14 for dissipating heat away from a mounting region 16 of the fastening element 10 into a ventilating region 18 of the fastening element 10. The heat-conducting element preferably includes a metallic sub-region which is cooled by a flow of air directed of the ventilating region 18. A clamping element 22 may also be present for clamping the fastening means 10 in a housing 24 and the bearing device is intended to form part of a labyrinth fan 20. A ventilating device having a fan wheel 26 for cooling a heat-conducting means 14 is also disclosed.

Description

ROBERT BOSCH GMBH; D-70442 Stuttgart Bearing device and ventilating device

Prior art

The invention starts from a bearing device according to the precharacterising clause of Claim 1 and from a ventilating device according to the precharacterising clause of Claim 9.

It has already been proposed to provide a bearing device having a fastening element for rotatably mounting a drive shaft of a hand-tool appliance. In this case, the fastening element is frequently intended for holding a ball bearing in which the drive shaft is mounted.

Advantages of the invention The invention starts from a bearing device having a fastening element for rotatably mounting a drive shaft of a handtool appliance.

It is proposed that the fastening element has a heat conducting means for dissipating heat from a mounting region of the fastening element into a ventilating region of the fastening element. It is thereby possible advantageously to avoid overheating of the fastening element in the mounting region. Damage, for example to seals or ball bearings, which might arise from overheating of the mounting region, can advantageously be avoided.

Furthermore, good thermal contact between the mounting region and the ventilating region can be producible without dust-laden air having to penetrate into the mounting region. Increased wear due to dust-induced contamination of the mounting region can advantageously be avoided.

"intended" is also to be understood in this context as meaning "designed" and "equipped". The solution according to the invention is usable, in principle, in all bearing arrangements which seem appropriate to a person skilled in the art. However, because of the typically high dust load, advantages can be achieved when it is used particularly in hand-tool machines and, because of the high mechanical loads of the bearing devices, particularly in drilling hammers or percussion drilling machines.

In a further configuration of the invention, it is proposed that the heatconducting means is intended for having a flow of air directed around it at least in a ventilating region. As a result, particularly effective heat dissipation from the mounting region can be achieved.

Furthermore, it is proposed that the heat-conducting means has at least one metallic subregion. Because of the typically high thermal conductance and the high stability of metallic substances, particularly robust and effective heat dissipation can be achievable.

A particularly constructional-space-saving integration of the heatconducting means in the hand-tool appliance can be achieved if an axis of rotation of the drive shaft forms an axis of symmetry of at least one subregion of the heat- conducting means.

In this case, a cost-effective construction of the heat- conducting means is achievable if the heat-conducting means has a cylindrical subregion which can particularly advantageously be intended for enclosing the drive shaft.

Good thermal contact and advantageous dust shielding can be achieved if the heat-conducting means is intended for forming part of a labyrinth fan.

If the bearing device has at least one clamping element, which is intended for clamping the fastening means to a housing, particularly quick and cost-effective assembly can be achievable.

In this case, further tolerance-compensating devices can be avoided if the clamping element is intended for ensuring tolerance compensation.

Furthermore, the invention starts from a ventilating device having a fan wheel for cooling a drive assembly of a hand tool machine.

It is proposed that the fan wheel is intended for cooling a heatconducting means for dissipating heat from a mounting region of the handtool machine into a ventilating region.

As a result, overheating of the mounting region can advantageously be avoided.

In this case, effective dust protection of the mounting region can be achieved if the ventilating device comprises a labyrinth fan.

Drawing Further advantages emerge from the following description of the drawing. Exemplary embodiments of the invention are illustrated in the drawing. The drawing, description and claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually as well and combine them to form appropriate further combinations.

In the drawing: Fig. 1 shows a sectional illustration of a drilling hammer having a bearing device and a fastening element for mounting a drive shaft, Fig. 2 shows a section along the line II-II in Figure 1, Fig. 3 shows the fastening element from Figures 1 and 2, Fig. 4 shows the fastening element from Figure 3 in a plan view, Fig. 5 shows a drive assembly having a ventilating device, the fastening element and the drive shaft, Fig. 6 shows an alternative bearing device of a drilling hammer having a fastening element, Fig. 7 shows the fastening element from Figure 6, Fig. 8 shows part of a housing of a drilling hammer having a clamping element in a further configuration of the invention, Fig. 9 shows a sectional illustration of a drilling hammer having a bearing device and a fastening element for mounting a drive shaft in a further configuration of the invention, Fig. 10 shows the fastening element and a motor housing from Figure 9 in a plan view, Fig. 11 shows the fastening element from Figures 9 and 10 in a sectional illustration, Fig. 12 shows a sprung tolerance-compensating element in a further configuration of the invention, Fig. 13 shows a sprung tolerance-compensating element in a further configuration of the invention, and Fig. 14 shows a wedge-shaped tolerance-compensating element in a further configuration of the invention.

Description of the exemplary embodiments

Figure 1 shows a bearing device having a fastening element 10 for rotatably mounting a drive shaft 12 of a hand-tool appliance configured as a drilling hammer, which shaft is fixedly connected to an armature of a drive assembly 28 embodied as an electric motor. A first bevel gearwheel 30 forced onto the drive shaft 12 meshes with a second bevel gearwheel 32 connected to a gear shaft 34. The bevel gearwheels 30, 32 transmit a rotary motion of the drive shaft 12 to the gear shaft 34, which in turn drives a percussion mechanism and a rotary drive of the drilling hammer comprising the bearing device.

The fastening element 10 is embodied as a metal fastening plate 10 and has a subregion 18 which constitutes a ventilating region 18 of the fastening element 10, has the shape of a cylinder lateral surface and is metallic. The fastening element 10 and in particular the subregion 18 assumes the function of a heat-conducting means 14 which extends between a mounting region 16 of the fastening element 10 and the ventilating region 18. The mounting region 16 is an annular region which extends around a circular opening of the fastening element 10, which opening is encompassed by the subregion 18. The mounting region 16 is intended for holding a ball bearing 36 of the bearing device, which bearing may heat up greatly during operation of the drilling hammer. The heat absorbed in the mounting region 16 is conducted, during operation, by the metal of the fastening element 10 to the ventilating region 18, from where the heat can radiate from an inner surface and from an outer surface. The opening is intended for passing through the drive shaft 12, the axis of rotation of which forms an axis of symmetry of the subregion 18 in the shape of a cylinder lateral surface.

A ventilating device having a fan wheel 26 for cooling the drive assembly 28 of the hand-tool machine embodied as a drilling hammer is, furthermore, intended for continuously directing a flow of air around the ventilating region 18 of the fastening element 10 or of the heat-conducting means 14 during operation in order to ensure improved removal of the heat. For this purpose, the fan wheel 26 has, at a rear side facing the fastening element 10, a labyrinth fan 20 which is formed, in part, integrally on the fan wheel 26 and comprises two lamellae, running round the axis of symmetry of the drive shaft 12 and in the shape of a cylinder lateral surface, and a push-on sleeve.

The push-on sleeve, in the shape a cylinder lateral surface and constructed in one piece with the fan wheel 26, is intended for pushing the fan wheel 26 onto the drive shaft 12, which bears against an inner surface of the push-on sleeve, while an outer surface of the push-on sleeve forms an inner wall of the labyrinth fan 20. The ventilating region 18 projects into an interspace between the outer surface of the push-on sleeve of the fan wheel 26 and a first lamella of the labyrinth fan 20. A lamella formed integrally on a housing 24 of the drilling hammer projects into the annular interspace between the first and the second lamella of the labyrinth fan 20. During operation, air is forced to flow along a path, meandering in the radial direction, between the lamellae through to the ventilating region 18, so that dust particles are impeded from penetrating into the region of the ventilating region 18. During operation, the fan wheel 26 rotates and generates an airstream which flows quickly past the surfaces of the ventilating region 18 and thereby flows around the ventilating region 18, so that the fan wheel 26 is intended for cooling the heat-conducting means 14, which is designed for dissipating the heat from the mounting region 16.

In the sectional illustration in Figure 2, it becomes clear how the fastening element 10 is fastened to the housing 24 of the drilling hammer. For this purpose, the fastening element 10 has two opposite tabs 38, 38' shaped into hooks, in which there engages a clamping element 22 having corresponding hook elements and embodied as a band-spring part. The clamping element 22 encompasses part of the housing 24, formed from plastic, which in turn encompasses the gear shaft 34. The clamping element 22 in the assembled state clamps the fastening element 10, and with it the ball bearing 36, the drive shaft 12 and the fan wheel 26, to the housing 24 in the axial direction with respect to the axis of rotation of the drive shaft 12. The hook elements of the clamping element 22 are formed in one piece with the latter from a band spring and have a radius of curvature of about 3 mm, which allows elastic deformation of the clamping element 22 and thus ensures tolerance compensation between housing 24 and fastening element 10.

During an assembly operation, first the fan wheel 26, then the fastening element 10, then the ball bearing 36 and finally the bevel gearwheel 30 are pushed onto the drive shaft 12 (Figure 5). The assembly unit thus produced is then clamped to the housing 24 by the clamping element 22.

In Figures 6 - 14, details or components of further configurations of the invention are illustrated. In the description, essentially differences from the exemplary embodiment illustrated in Figures 1 - 5 are discussed. As regards features which remain the same, reference may be made to the description relating to Figures 1 - 5. Features and components which are essentially functionally identical are given identical reference symbols.

In the exemplary embodiment illustrated in Figures 6 - 8, tabs 38, 38' of a fastening element 10 have holes with threads which are intended for receiving screws 40, 40', by

I

means of which the fastening element 10 is screwed to a housing 24. The housing 24 encloses a percussion mechanism, is constructed in a plurality of parts and comprises a lower shell 42 and an upper shell 44. A clamping element 46 encompasses the upper shell 44, to which it is fastened by means of a screw 52, and engages in ribs of the lower shell 42 (Figure 8).

In the exemplary embodiment illustrated in Figures 9 - 11, tabs 38, 38' of a fastening element 10 are lengthened compared with the previous exemplary embodiments. As a result, the fastening element 10 is suitable for diagonal arrangement in a cross-section of a housing 24 of the shape of a rounded square (Figure 10). During assembly, the housing 24 is screwed to a motor housing 48. In so doing, the tabs 38, 38' of the fastening element 10 are clamped between the housing 24 and the motor housing 48 and put under a slight bending stress for tolerance compensation.

Figures 12 - 14 show several U-shaped tolerance- compensating elements 50 - 50'', which are intended for arrangement between a fastening element 10 and a housing 24. The tolerance-compensating elements 50, 50' each have spring elements on the legs of their U-shape, which are embodied in the tolerance- compensating element 50 (Figure 12) as elongate tabs protruding at a small angle from the legs and in the tolerance-compensating element 50' (Figure 13) as arched subregions. The tolerance-compensating element 50'' (Figure 14) has wedge-shaped legs intended for insertion between the fastening element 10 and the housing 24. Tolerances can be compensated by adjusting the depth of insertion. Furthermore, a bearing device comprising the tolerance-compensating element 50'' can be put under a i prestress in the axial direction, which can lead to avoidance of play. it, 1

ROBERT BOSCH GMBH; 70442 Stuttgart Reference symbols Fastening element 12 Drive shaft 14 Heat-conducting means 16 Mounting region 18 Ventilating region Labyrinth fan 22 Clamping element 24 Housing 26 Fan wheel 28 Drive assembly Bevel gearwheel 32 Bevel gearwheel 34 Gear shaft 36 Ball bearing 38 Tab Screw 42 Lower shell 44 Upper shell 46 Clamping element 48 Motor housing Tolerance-compensating element 52 Screw ROBERT BOSCH GMBH; D-70442 Stuttgart Claims 1. Bearing device having a fastening element (10) for rotatably mounting a drive shaft (12) of a hand-tool appliance, characterized in that the fastening element (10) has a heat-conducting means (14) for dissipating heat from a mounting region (16) of the fastening element (10) into a ventilating region (18) of the fastening element (10).

2. Bearing device according to Claim 1, characterized in that the heatconducting means (14) is intended for having a flow of air directed around it at least in a ventilating region (18).

3. Bearing device according to one of the preceding claims, characterized in that the heat-conducting means (14) has at least one metallic subregion (18).

4. Bearing device according to one of the preceding claims, characterized in that an axis of rotation of the drive shaft (12) forms an axis of symmetry of at least one subregion (18) of the heat-conducting means (14).

Claims

5. Bearing device according to Claim 4, characterized in that the heat-

conducting means (14) has a cylindrical subregion (18).

6. Bearing device according to one of the preceding claims, characterized in that the heat-conducting means (14) is intended for forming part of a labyrinth fan (20).

7. Bearing device according to one of the preceding claims, characterized by at least one clamping element (22), which is intended for clamping the fastening means (10) to a housing (24).

8. Bearing device according to Claim 7, characterized in that the clamping element (22) is intended for ensuring tolerance compensation.

9. Ventilating device having a fan wheel (26) for cooling a drive assembly (28) of a hand-tool machine, characterized in that the fan wheel (26) is intended for cooling a heat-conducting means (14) which is intended for dissipating heat from a mounting region (16) of the hand-tool machine into a ventilating region (18).

10. Ventilating device according to Claim 9, characterized in that a labyrinth fan (20) is formed integrally on the fan wheel (26).

11. A bearing device substantially as herein described with reference to the accompanying drawings. a,

12. A ventilating device substantially as herein described with reference to the accompanying drawings.