Electropneumatic impact mechanism

Abstract

An electro-pneumatic percussion mechanism for a hand-held electric power tool, in particular a hammer drill and / or a pneumatic chisel, wherein the percussion mechanism has: a drive housing; a guide tube which is at least partially arranged in the drive housing; an actuating piston which is axially movable in the guide tube; a connecting rod which is connected to the actuating piston; and an eccentric which is connected on one side to the connecting rod and is rotatably mounted on the other side relative to the drive housing, wherein the percussion mechanism has a support body on which the eccentric is rotatably mounted by means of a sliding bearing pair.

Description

Technical Field

[0001] The present invention relates to an electro-pneumatic percussion mechanism for a hand-held power tool, in particular a hammer drill and / or a chisel hammer. The percussion mechanism is provided with: a drive housing; a guide tube which is at least partially arranged in the drive housing; an actuating piston which is movable in the guide tube; a connecting rod which is connected to the actuating piston; and an eccentric. The eccentric is connected to the connecting rod on one side and is rotatably mounted relative to the drive housing on the other side. Background Art

[0002] Percussion mechanisms of the type mentioned at the beginning and hand-held power tools having such percussion mechanisms are basically known from the prior art. Summary of the Invention

[0003] The object of the present invention is to provide a percussion mechanism which can be mounted and removed relatively simply and is thus cost-effective.

[0004] This object is achieved in that the percussion mechanism has a support body on which the eccentric is rotatably mounted by means of a sliding bearing pair. This has the advantage that relatively complex mountings for the eccentric, including ball bearings, needle bearings, etc., can be dispensed with, so that fewer parts need to be assembled.

[0005] In a particularly preferred refinement, the support shaft is made of plastic or includes such plastic. It has been found advantageous that the support shaft is made of or includes carbon fiber reinforced plastic. The plastic can include one or more of the following base polymers: polyketone (PK), polyamide (PA), polybutylene terephthalate (PBT), polyphthalamide (PPA), polyphenylene sulfide (PPS) and / or polyetheretherketone (PEEK). The plastic can have one or more additives for improving the sliding properties (especially in the case of lack of lubrication and dry operation), in particular molybdenum disulfide, polytetrafluoroethylene (PTFE) and / or graphite. The finding included in the present invention in this regard is that a support shaft made of or including such plastic is much lighter than the steel support shafts known in the prior art.

[0006] In a further preferred refinement, the support body is configured as a support shaft different from the eccentric. It has been found advantageous that the eccentric has a central hole which is paired with the support shaft via a clearance fit and thus forms a sliding bearing pair. The support shaft can accordingly provide a radially extending surface for the eccentric.

[0007] In a further preferred improvement, the support shaft has a collar that provides an axial sliding surface for the eccentric. It has been found advantageous for the support shaft to be fixed in a form-fitting manner via its collar to prevent rotation relative to the drive housing. The collar can have a wavy circumferential tooth section that forms a form fit with a corresponding tooth section in the end plate of the drive housing relative to the circumferential direction of the support shaft. In a particularly preferred improvement, the eccentric contacts the collar directly. Alternatively or additionally, the eccentric is fixed by the collar in the axial direction to prevent detachment from the connecting rod.

[0008] In a particularly preferred improvement, the support shaft mates with the drive housing via a clearance fit on the side of the collar facing the eccentric. Alternatively or additionally, the support shaft can be fixed in the drive housing in the axial direction by a threaded connection on the side of the collar facing the eccentric.

[0009] As an alternative to the improvement of the support body as the support shaft, the support body can be configured as a journal and / or be integrally formed with the drive housing. It has been found advantageous for the sliding bearing pair to have a sliding bearing bushing arranged between the eccentric and the journal. It has also been found advantageous for the sliding bearing bushing to be pressed into the eccentric. In a particularly preferred improvement, the taper of the journal corresponds to the taper of the sliding bearing bushing. To improve the sliding performance between the end plate and the eccentric, a sliding coating, such as a PTFE sliding coating, can be provided between the end plate and the eccentric.

[0010] In all of the previously described exemplary embodiments, the drive housing can have a closing cover that has at least one retaining lip on the side facing the eccentric. It has been found advantageous for the profile of the retaining lip to at least partially, preferably entirely, follow the circular path of the eccentric points of the eccentric. A plurality of retaining lips can be provided, with each retaining lip being configured concentrically relative to one another. The diameters of the retaining lips can be different from one another. In this way, the connecting rod and the eccentric are preferably fixed to prevent axial detachment.

[0011] In all of the previously described exemplary embodiments, the eccentric can preferably be configured as an external toothed gear that can preferably be rotationally driven via an electric motor incorporated in a hand-held power tool.

[0012] This object is also achieved by a hand-held electric power tool, in particular a hammer drill and / or a chisel hammer, which is provided with an impact mechanism of the above-described type.

[0013] Further advantages will become apparent from the following description of the drawings. The various exemplary embodiments of the present invention are shown in the drawings. The drawings, the description, and the claims contain many combinations of features. Those skilled in the art will also conveniently consider these features individually and combine them to form useful further combinations. Description of the Drawings

[0014] In the drawings, identical and similar parts are denoted by the same reference numerals. In the drawings:

[0015] FIG. 1 shows a first exemplary embodiment of an impact mechanism according to the present invention; and

[0016] Figure 2 shows a second exemplary embodiment of the impact mechanism according to the present invention. Detailed Description of the Invention

[0017] In Figure 1A is shown a first preferred exemplary embodiment of an electro-pneumatic impact mechanism 70 of a hand-held electric power tool 100 (see Figure 1B , for example in the form of a chipping hammer).

[0018] The electro-pneumatic impact mechanism 70 has a drive housing 60 and a guide tube 50, wherein the guide tube 50 is at least partially arranged in the drive housing 60. The electro-pneumatic impact mechanism 70 also has an actuating piston 40 movable in the guide tube 50, a connecting rod 30 coupled to the actuating piston 40, and an eccentric wheel 20. The eccentric wheel 20 is coupled to the connecting rod 30 on one side and is rotatably mounted relative to the drive housing 60 via an end plate 10 of the drive housing 60 on the other side. The end plate 10 is integrated in the drive housing 60. The eccentric wheel 20 is in the form of an external gear and can be rotatably driven via an electric motor (not shown here).

[0019] According to the present invention, the impact mechanism 70 has a support 25, and the eccentric wheel 20 is rotatably mounted on the support by a sliding bearing pair 28. The support 25 is configured here as a support shaft 26 different from the eccentric wheel 20. The support shaft 26 is made of, for example, carbon fiber-reinforced PEEK plastic, which has polytetrafluoroethylene (PTFE) to improve the friction properties. The eccentric wheel 20 has a central hole 22, which is paired with the support shaft 26 via a clearance fit SP, thereby forming the sliding bearing pair 28.

[0020] In particular, it can also be collected from Figure 1C (extracted from the Figure 1A support shaft) that the support shaft 26 has a collar 27 extending in the radial direction RR. The collar 27 provides an axial sliding surface AG for the eccentric wheel 20. The support shaft 26 is here fixed in a form-fitting manner by its collar 27 to prevent rotation relative to the drive housing 60, more precisely to prevent rotation relative to the end plate 10 of the drive housing 60. The form fit is provided by a corrugated circumferential tooth portion 27' on the collar 27. From Figure 1AIt can be collected that the eccentric wheel 20 is in direct contact with the collar 27. The eccentric wheel 20 is fixed by the collar 27 in the axial direction AR to prevent disengagement from the connecting rod 30 (downward in Figure 1A ).

[0021] On the side of the collar 27 facing the eccentric wheel 20, the support shaft 26 is paired with the transmission housing 60 via a plate clearance fit SS, more precisely with the end plate 10 of the transmission housing 60. The threaded connection 11 fixes the support shaft 26 in the transmission housing 60 in the axial direction AR.

[0022] Finally, the transmission housing 60 has a closing cover 65 which has four retaining lips 67 on the side facing the eccentric wheel 20, and the contours of these retaining lips follow (exactly or concentrically) the circular path 23 of the eccentric point 21 of the eccentric wheel 20. In this way, the connecting rod 30 and the eccentric wheel 20 are fixed to prevent disengagement in the axial direction AR (upward in Figure 1A ).

[0023] Optionally provided with a separating cap 71, which is arranged between the main housing 61 and the cover housing 65 and engages around at least the eccentric wheel 20.

[0024] In Figure 2 is shown a second preferred exemplary embodiment of the electro-pneumatic impact mechanism 70 of a hand-held electric power tool 100 (see Figure 1B , for example in the form of a chisel hammer).

[0025] The electro-pneumatic impact mechanism 70 also has a transmission housing 60 and a guide tube 50, wherein the guide tube 50 is at least partially arranged in the transmission housing 60. The electro-pneumatic impact mechanism 70 also has an actuating piston 40 movable in the guide tube 50, a connecting rod 30 coupled to the actuating piston 40, and an eccentric wheel 20. The eccentric wheel 20 is coupled to the connecting rod 30 on one side and is rotatably mounted relative to the transmission housing 60 via the end plate 10 of the transmission housing 60. The end plate 10 is integrated in the transmission housing 60. The eccentric wheel 20 is in the form of an external toothed gear and can be rotatably driven via an electric motor (not shown here) of the hand-held electric power tool 100.

[0026] Compared with the exemplary embodiment of FIG. 1, in which the support 25 is configured as a support shaft 26 different from the eccentric wheel 20, in Figure 2In the case of the impact mechanism 70, the support 25 is configured as a support journal 24 integrated with the drive housing 60. A sliding bearing pair 28 is provided between the eccentric wheel 20 and the support journal 24. The sliding bearing bush 29 is pressed into the central hole 22 of the eccentric wheel 20. In order to improve the sliding performance between the end plate 10 and the eccentric wheel 20, a PTFE sliding coating 12 is provided between the end plate 10 and the eccentric wheel 20.

[0027] The drive housing 60 also has a closing cover 65 which has a retaining lip 67 on the side facing the eccentric wheel 20, and the contour of the retaining lip follows the circular path 23 of the eccentric point 21 of the eccentric wheel 20. For example, three additional concentric retaining lips 67 are provided. In this way, the connecting rod 30 and the eccentric wheel 20 are fixed to prevent detachment in the axial direction AR (upward in Figure 2 ).

[0028] List of Reference Numerals

[0029] 10 End plate

[0030] 11 Threaded connector

[0031] 12 Sliding coating

[0032] 20 Eccentric wheel

[0033] 21 Eccentric point

[0034] 22 Central hole

[0035] 23 Circular path

[0036] 24 Support journal

[0037] 25 Support

[0038] 26 Support shaft

[0039] 27 Collar

[0040] 27’ Rotating tooth part

[0041] 28 Sliding bearing pair

[0042] 29 Sliding bearing bush

[0043] 30 Connecting rod

[0044] 40 Actuating piston

[0045] 50 Guide tube

[0046] 60 Drive housing

[0047] 65 Closing cover

[0048] 67 Retaining lip

[0049] 70 Impact mechanism

[0050] 71 Separation cap

[0051] 100 Handheld electric power tool

[0052] AG Axial sliding surface

[0053] AR Axial direction

[0054] RR Radial direction

[0055] SP Clearance fit

[0056] SS Plate clearance fit

Claims

1. An electro-pneumatic impact mechanism (70) for a hand-held electric power tool (100), wherein, The electro-pneumatic impact mechanism (70) has: a drive housing (60); a guide tube (50) which is at least partially arranged in the drive housing (60); an actuating piston (40) which is movable in the guide tube (50); a connecting rod (30) which is connected to the actuating piston (40); and an eccentric (20) which is connected to the connecting rod (30) on one side and is rotatably mounted relative to the drive housing (60) on the other side. Wherein, the electro-pneumatic impact mechanism (70) has a support body (25), and the eccentric (20) is rotatably mounted on the support body by means of a sliding bearing pair (28), wherein the support body (25) is configured differently from the support shaft (26) of the eccentric (20). It is characterized in that the support shaft (26) has a collar (27), and the collar provides an axial sliding surface (AG) for the eccentric (20), wherein the support shaft (26) is fixed in a form-fitting manner by means of its collar (27) to prevent rotation relative to the drive housing (60), and wherein the collar (27) has a wavy circumferential tooth part (27'), and the circumferential direction of the wavy circumferential tooth part relative to the support shaft (26) forms a form fit with a corresponding tooth part in the end plate (10) of the drive housing (60).

2. The electro-pneumatic impact mechanism (70) according to claim 1. It is characterized in that The support shaft (26) is made of plastic.

3. The electro-pneumatic percussion mechanism (70) according to claim 2, characterized in that, The support shaft (26) is made of carbon fiber reinforced plastic.

4. The electro-pneumatic impact mechanism (70) according to any one of claims 1 to 3. It is characterized in that The eccentric (20) has a central hole, and the central hole is paired with the support shaft (26) via an interference fit (SP), and thus forms the sliding bearing pair.

5. The electro-pneumatic impact mechanism (70) according to any one of claims 1 to 3. It is characterized in that The eccentric (20) is in direct contact with the collar (27), and / or the eccentric (20) is fixed in the axial direction (AR) by the collar (27) to prevent detachment from the connecting rod (30).

6. The electro-pneumatic impact mechanism (70) according to any one of claims 1 to 3. It is characterized in that The support shaft (26) is paired with the drive housing (60) via an interference fit on the side of the collar (27) facing the eccentric (20), and / or the support shaft is fixed in the drive housing (60) in the axial direction (AR) by a threaded connection.

7. The electro-pneumatic impact mechanism (70) according to any one of claims 1 to 3. It is characterized in that The drive housing (60) has a closing cover (65), and the closing cover has a retaining lip (67) on the side facing the eccentric (20), and the contour of the retaining lip at least partially follows the circular path (23) of the eccentric point (21) of the eccentric (20).

8. The electro-pneumatic impact mechanism (70) according to any one of claims 1 to 3. It is characterized in that The eccentric (20) is configured as an external gear which can be rotatably driven via an electric motor incorporated in a hand-held electric power tool (100).

9. The electro-pneumatic impact mechanism (70) according to any one of claims 1 to 3, characterized in that, The hand-held electric power tool (100) is a hammer drill and / or a rotary hammer.

10. A hand-held electric power tool (100) having an electro-pneumatic percussion mechanism (70) as claimed in one of the preceding claims.

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