EP1861631A1

EP1861631A1 - Bearing arrangement for a hand tool

Info

Publication number: EP1861631A1
Application number: EP06708043A
Authority: EP
Inventors: Andre Ullrich
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-03-11
Filing date: 2006-02-06
Publication date: 2007-12-05
Also published as: WO2006094865A1; DE102005011326A1; CN101137855A

Abstract

The invention relates to a bearing arrangement (51) of a shaft (52) of a hand tool (2), especially a boring hammer (3), comprising a bearing region (23) which is associated with the shaft (52) and with which a lubricant store (25) filled with lubricant (24) is associated for the lubrication thereof. According to the invention, the lubricant store (25) is sealed by means of at least one sealing element (31, 32).

Description

Bearing arrangement of a hand tool

The invention relates to a bearing arrangement of a shaft of a hand tool, in particular a hammer drill, with a shaft associated bearing portion, which is associated with its lubrication filled with lubricant lubricant depot.

Bearing arrangements such as the present are used, for example, in rotary hammers, particularly in connection with switching devices, such as for switching various operating modes. On the waves used here, on the one hand for the transmission of forces, rotation, torque and / or pulse, on the other hand used for switching in the broadest sense, components are often stored that require at least one, in relation to the bearing diameter of great length two bearings , For example, the bearing assembly may be formed as a swash bearing arrangement, which serves to connect and disconnect a striking mechanism. Such a swash bearing arrangement can then take two different modes. In a first mode of operation "drilling with impact", the swash bearing is mechanically connected to the drive shaft of the hammer by means of a suitable switching mechanism, so that it can rotate with the drive shaft and drive the hammer mechanism Swing bearing decoupled from the drive shaft, so that the drive shaft can rotate freely without turning the swash bearing. Depending on the operating mode, the bearing between the swash-bearing arrangement and the drive shaft is claimed differently. After a long period of operation of the hand tool there is a risk that the swash bearing can fail due to heavy stress.

For lubrication of the bearings, it is known to introduce lubricant into the space of the bearing assembly and / or in the housing of the hand tool. To a lubricant storage too cause it is known to form lubricant deposits in the field of bearing arrangement or in the field of bearings. Since such hand tools occupy different operating positions in the room during operation, the lubricant introduced into the housing of the hand tool and / or the operating space of the bearing arrangement and / or the lubricant reservoir can, within the housing and / or following the principle of gravity the operating room flow, especially for longer operating time and associated higher temperature. In addition, during operation of the hand tool there is the risk that lubricant located on the bearing assembly and, in particular, lubricant located on the shaft will be thrown off and / or will flow out of the lubricant reservoir and thereby be lost for lubrication. Overall, deficient lubrication conditions result.

The present invention is characterized in that the lubricant reservoir is sealed by means of at least one sealing element. This ensures that the lubricant in the lubricant reservoir over the entire life of the hand tool, in particular the hammer remains. Even if the hand tool is operated in different positions, the sealing element prevents the lubricant from flowing out of or out of the way.

In an advantageous development, it is provided that the sealing element is assigned to the storage area. By this arrangement, a lubricant drainage is largely avoided, especially in the storage area.

A further advantageous embodiment of the invention provides that the sealing element connects directly to the storage area. As a result, a very good lubricant retention is effected directly in the storage area. It will therefore prevent lubricant from the storage area escapes, as may occur in the above-mentioned, known arrangements. The lubricant seal according to the invention furthermore makes it possible for no other lubricant originating, for example, from the drive motor and / or gearbox of the hand tool, to penetrate into the bearing area and cause damage there due to incompatibility with the lubricant specially introduced for the bearing. Thus, it is possible to use in the storage area a special lubricant, which differs from other lubricants used in the hammer drill, without the various lubricants can mix. In addition, the ingress of dirt is prevented in the storage area, as he can be registered for example by a cooling air guide in the housing of the hand tool or otherwise reaches the vicinity of the storage areas. Thus, in addition to a better, namely long-lasting and specific lubrication and a higher reliability by reducing the risk of failure is given, which is due to any contamination entry.

A further development of the invention provides that the bearing arrangement is designed as a swash-bearing arrangement and can be operated by means of the shaft designed as a drive shaft. The swash-bearing arrangement according to the invention has a much longer life expectancy compared to conventional swash-bearing arrangements due to the always ensured lubrication.

A further development of the invention provides that the bearing arrangement has a first and a second bearing element, wherein the first bearing element is rotatably coupled in a first mode with the drive shaft and stored in a second mode on the rotating drive shaft by means of the storage area. By this arrangement, the switching between different operating modes of the hand tool is effected, wherein the Lagerele- - A -

benefit from the inventive lubricant retention by much longer life.

A development of the invention provides that the sealing element is arranged between the first bearing element and the drive shaft. It is advantageous if at least one bearing is arranged between lubricant reservoir and sealing element, so that this bearing is supplied with lubricant, but the lubricant can not escape from the storage area. In particular, it is possible to arrange the sealing element at the axial end of the bearing area between the first bearing element and the drive shaft.

An arrangement between the first bearing element and the drive shaft is also to be understood that the sealing element between the first bearing element and a fixedly arranged on the drive shaft component, for example, a gear is arranged. It is always important that the lubricant reaches the storage area, but can not escape, so that the storage area does not "dry".

Furthermore, it is advantageous that the lubricant reservoir is arranged in a receiving space formed between the drive shaft and the first bearing element. This receiving space comprises the space formed by the bearing clearance between the first bearing element and the drive shaft. In order to provide additional receiving space for lubricant, it is possible to provide one or more recesses in the drive shaft and / or in the bearing element. Such a recess can be realized, for example, as a non-circumferential radial recess or circumferential recess. The created by the recess or recesses receiving space is thus a lubricant receiving space which is filled with lubricant and forms a correspondingly large lubricant reservoir. In particular, it is advantageous if the receiving space is an annular space. The annular space may be formed by an annular groove running in the lateral surface of the drive shaft and / or an annular groove running around in the inner side of the first bearing element. It is also possible to arrange a plurality of annular grooves in the axial direction next to each other. The receiving space provided by the annular groove is the lubricant accommodating space filled with the lubricant and forming the lubricant reservoir. Alternatively or additionally, it may also be provided for the first bearing element to be mounted on the drive shaft by means of at least one bearing, preferably two bearings arranged axially spaced from one another. Due to the overall height of the bearing (s) belonging to the bearing area, an annular space is formed between the drive shaft, the first bearing element and the bearing or the two bearings, which serves as a lubricant receiving space.

A development of the invention provides that the annular space-viewed in the longitudinal extent of the drive shaft-is axially sealed by means of the sealing element. This ensures that the lubricant does not escape along the drive shaft or the bearing element in the axial direction.

In particular, it is advantageous if the annular space is sealed at its two axial ends by means of a respective sealing element. As a result, a well-closed area for receiving the lubricant is created. Accordingly, it is to be provided to arrange the bearing area in which the first bearing element is mounted on the drive shaft between the two sealing elements, so that the bearing area is supplied with lubricant from the lubricant reservoir.

The sealing element is preferably designed as a sealing ring. Furthermore, it is advantageous that the sealing element is designed as an O-ring, which preferably consists of elastic material.

A development of the invention provides that the sealing element is designed as a shaft seal, which is also to be referred to as a shaft seal or radial seal.

It is further provided that the sealing element is partially received in a radial direction in a recess of the drive shaft and / or a depression in the first bearing element. As a result, the sealing element is fixed in the axial direction, so that it can not move. The recess, which is designed in particular as a circumferential recess, also offers the possibility of creating a relatively large contact surface between the sealing element and the recess, which guarantees a good seal. In particular, the cross-sectional shapes of recess and sealing element are matched to one another in a form-fitting manner. In particular, the recess is formed as an annular groove.

According to various developments of the invention, it is provided that the bearing area has at least one bearing designed as a sliding bearing and / or as a roller bearing and / or as a needle bearing and / or as a ball bearing. Preferably, two mutually spaced bearings are provided, which have between them filled with lubricant lubricant depot, this arrangement is completed on both sides by a respective sealing element such that the lubricant indeed passes to the camps, but can not escape from the storage area ,

Advantageous developments of the invention will become apparent from the dependent claims.

The drawings illustrate the invention with reference to two embodiments, in which: FIG. 1 shows a swash-bearing arrangement according to a first exemplary embodiment,

Figure 2 is a detail view of the first embodiment and

Figure 3 is a detail view of another embodiment of the invention.

1 shows a sectional view of a bearing assembly 51, namely a swash bearing assembly 1, a hand tool 2, not shown, namely a hammer drill. 3

The swash-bearing arrangement 1 allows two modes of operation during operation. In a first mode, drilling with impact, the swash bearing assembly 1 is driven by a shaft formed as a drive shaft 52 52 such that a piston 5 of a striking mechanism 6, not shown, is moved back and forth along a striking axis 7, so that due the pendulum movement of the piston 5 the striking mechanism 6 performs the impact function. In a second mode, drilling without impact, the swash-bearing assembly 1 is disengaged from the drive shaft 4, that is not driven, and thus the piston 5 is not moved.

The swash-bearing arrangement 1 has a first bearing element 8 and a second bearing element 9. In the first mode, drilling with impact, the first bearing element 8 rotates together with the drive shaft 4 about the drive shaft 10; in the second mode, drilling without impact, the first bearing element 8 does not rotate. The first bearing element 8 has on its outer side 11 an obliquely encircling groove 12. This forms together with a circumferential on the inner side 13 of the second bearing element 9 groove 14, a swash bearing 15 having balls 16. The bearing elements 8 and 9 are rotatably supported by means of the swash bearing 15 to each other. The thus formed swash bearing 15, which may also be referred to as a self-aligning bearing 17, in the first mode, drilling with shock, due to the rotational movement of the first bearing element 8 to a pendulum motion of the second bearing element 9. This moves via a bearing 18, the piston 5 of the Percussion 6.

On the drive shaft 4, two axially non-rotatably connected to the drive shaft 4 Axialführungsmittel 19 and 20 are arranged, which fix the first bearing element 8 in the axial direction on the drive shaft 4. The Axialführungsmittel 19 is designed as a gear 21, which performs more, not interesting here functions. About a switching mechanism, not shown, the first bearing element 8 in the first mode, drilling with impact, rotatably connected to the drive shaft 4. The first bearing element 8 supports by means of a bearing portion 23 on the drive shaft 4. The bearing portion 23 has two bearings 27 and 28 which are formed as rolling bearings 29 and 30. According to the invention, the axially spaced rolling bearings 29 and 30 each have a separate or preferably integrated sealing element 31 and 32. The two sealing elements 31 and 32 seal a lubricant reservoir 25 filled with lubricant 24 in such a way that the lubricant 24 lubricates the position region 23, ie the roller bearings 29 and 30, but can not escape along the drive shaft 4 in the axial direction. The lubricant reservoir 25 is formed in a receiving space 47 formed between the drive shaft 4, the first bearing element 8, and the two sealing elements 31 and 32, here as an annular space 26. The thus formed annular space 26 is closed at its two axial ends 34 and 35 by the two sealing elements 31 and 32.

FIG. 2 shows a detailed representation of the lubricant reservoir 25 described in FIG. 1 sealed by means of sealing elements 31 and 32, likewise in a sectional view. The reference numerals correspond to those of Figure 1. In particular, in FIG two rolling bearings 29 and 30 shown in detail with the sealing elements 31 and 32. The rolling bearings 29 and 30 each have a cage 45 and 46 for guiding rollers 33 and in each case the circumferentially extending sealing element 31 and 32. The cages 45 and 46 are pressed into the first bearing element 8, and the two sealing elements 31 and 32, which are formed as elastic O-rings 37 and 38, each sealingly against the drive shaft 4. The two rolling bearings 29 and 30 are respectively arranged that the rollers 33 are in communication with the lubricant reservoir 25. Thus, lubricant 24 can get out of the lubricant reservoir 25 to the rollers 33 and lubricate them. However, the lubricant 24 can not escape to the outside due to the sealing function of the two O-rings 37 and 38. The annular space 26 is closed on all sides, in particular at its two axial ends 34 and 35.

Figure 3 shows a detailed view of another embodiment, also in a sectional view. The bearing area 23 is formed in this embodiment as a sliding bearing 36 which extends over the entire axial length of the first bearing element 8. The annular space 26 formed between the drive shaft 4 and the first bearing element 8 is closed by means of the two O-rings 37 and 38 at its two axial ends 34 and 35. The O-rings 37 and 38 are fixed by annular grooves 39, 40, 41 and 42 in the axial direction and act there sealingly. On the drive shaft 4, the annular grooves 39 and 40 are arranged spaced from each other. You are the annular grooves 41 and 42 opposite, which are formed on the first bearing element 8. Also in this embodiment, the annular space 26 is closed at its two axial ends 34 and 35, so that no lubricant 24 can escape from it.

Claims

claims

1. Bearing arrangement (51) of a shaft (52) of a hand tool (2), in particular a hammer drill (3), with one of the shaft (52) associated bearing portion (23) to its lubrication with a lubricant (24) filled Lubricant depot (25) is assigned, characterized in that the lubricant depot (25) by means of at least one sealing element (31, 32) is sealed.

2. Bearing arrangement according to claim 1, characterized in that the sealing element (31, 32) is assigned to the storage area (23).

3. Bearing arrangement according to one of the preceding claims, characterized in that the sealing element (31, 32) directly adjoins the bearing area (23).

4. Bearing arrangement according to one of the preceding claims, characterized in that it is designed as a swash-bearing arrangement (1) and by means of the drive shaft (4) formed in the shaft (52) is operable.

5. Bearing arrangement according to one of the preceding claims, characterized in that it comprises a first and a second bearing element (8,9), wherein the first bearing element (8) in a first mode rotatably coupled to the drive shaft (4) and stored in a second mode on the rotating drive shaft (4) by means of the bearing area (23).

6. Bearing arrangement according to one of the preceding claims, characterized in that the sealing element (31, 32) between the first bearing element (8) and the drive shaft (4) is arranged.

7. Bearing arrangement according to one of the preceding claims, characterized in that the lubricant depot (25) in a between the drive shaft (4) and the first bearing element (8) formed receiving space (47) is arranged.

8. Bearing arrangement according to one of the preceding claims, characterized in that the receiving space (47) is an annular space (26).

9. Bearing arrangement according to one of the preceding claims, characterized in that the annular space (26) -in the longitudinal extension of the drive shaft (4) viewed axially by means of the sealing element (31, 32) is sealed.

10. Bearing arrangement according to one of the preceding claims, characterized in that the annular space (26) at its two axial ends (34,35) by means of a respective sealing element (31, 32) is sealed.

11. Bearing arrangement according to one of the preceding claims, characterized in that the sealing element (31, 32) is designed as a sealing ring.

12. Bearing arrangement according to one of the preceding claims, characterized in that the sealing element (31, 32) as an O-ring (37, 38) is formed.

13. Bearing arrangement according to one of the preceding claims, characterized in that the sealing element (31, 32) is formed as a llll sealing ring.

14. Bearing arrangement according to one of the preceding claims, characterized in that the sealing element (31, 32) in the radial Direction is partially received in a recess of the drive shaft (4) and / or the first bearing element (8).

15. Bearing arrangement according to one of the preceding claims, characterized in that the recess as an annular groove (39,40,

41, 42) is formed.

16. Bearing arrangement according to one of the preceding claims, characterized in that the bearing region (23) has at least one bearing (27) designed as a sliding bearing (36).

17. Bearing arrangement according to one of the preceding claims, characterized in that the bearing region (23) has at least one bearing (27, 28) designed as a roller bearing (29, 30).

18. Bearing arrangement according to one of the preceding claims, characterized in that the bearing region (23) has at least one bearing designed as a needle bearing (27,28).

19. Bearing arrangement according to one of the preceding claims, characterized in that the bearing region (23) has two axially spaced bearings (27,28), wherein between the bearings (27,28) the lubricant reservoir (25).

20. Bearing arrangement according to one of the preceding claims, characterized in that the sealing element (31, 32) in the bearing (27,28) is integrated.

21. Bearing arrangement according to one of the preceding claims, characterized in that the lubricant (24) is lubricating grease.