Handheld electric power tool

Abstract

A handheld electric power tool, in particular a hammer drill and / or a cutting hammer, has an electro-pneumatic impact mechanism, which has a transmission housing, a guide tube at least partially arranged in the transmission housing, an excitation piston movable in the guide tube in the axial direction, a connecting rod connected to the excitation piston, and an eccentric wheel, which is connected to the connecting rod on one side and is rotatably mounted relative to the transmission housing via an end plate of the transmission housing on the other side, wherein the transmission housing is subdivided into at least a main housing and a cover housing separate from the main housing, so that the guide tube is at least partially supported on the main housing by the cover housing.

Description

Technical Field

[0001] The present invention relates to a handheld electric power tool, in particular a hammer drill and / or a cutting hammer, having an electro-pneumatic impact mechanism. The electro-pneumatic impact mechanism comprises a transmission housing, a guide tube at least partially arranged in the transmission housing, an excitation piston axially movable in the guide tube, a connecting rod coupled to the excitation piston, and an eccentric. The eccentric is coupled to the connecting rod on one side and is rotatably mounted relative to the transmission housing on the other side via an end plate of the transmission housing. Background Art

[0002] Hand-held power tools of the type mentioned in the introduction are basically known from the prior art. Summary of the Invention

[0003] It is an object of the present invention to provide a handheld power tool which is easy to assemble and which at the same time is preferably configured in a relatively lightweight manner.

[0004] This object is achieved by the transmission housing being subdivided into at least a main housing and a cover housing separate from the main housing, so that the guide tube is at least partially supported on the main housing by the cover housing. In a particularly preferred configuration, the main housing is composed of metal and / or the cover housing is composed of plastic.

[0005] The present invention incorporates the discovery that in prior art handheld power tools, the transmission housing typically has a completely tubular section into which the guide tube must be laboriously screwed. Furthermore, the deep cuts typically required in prior art transmission housings are particularly expensive because a relatively large volume must be removed at a great depth within a relatively small hole. This material removal arises from the requirements of die casting. The cores for long inner diameters must have a certain slope to facilitate demolding. This typically results in a certain amount of mass accumulation, which in turn forms shrinkage cavities during die casting. These cavities represent a reduction in strength in these areas and often lead to crack propagation. According to the present invention, this disadvantage is avoided by subdividing the transmission housing into a main housing, preferably made of metal, and a cover housing, preferably made of plastic. This is because the transmission housing, with the cover housing removed, opens "upward." This allows for relatively easy insertion of the guide tube into the main housing and easier assembly of the excitation piston, connecting rod, and eccentric. The eccentric can also be inserted "from above" into the main housing through the large opening (i.e., the removed cover housing). In particular, the complicated process of screwing the eccentric pin into the connecting rod (or screwing the crank pin into the eccentric) and subsequently introducing the driving piston into the guide tube is dispensed with.

[0006] In particular, due to the preferred embodiment of the cover housing made of plastic, the weight of the transmission housing and thus the entire handheld power tool can be significantly reduced. In this regard, the present invention incorporates the discovery that the plastic can be arranged precisely in the region of the transmission housing where the minimum cooling air flow in the handheld power tool is located (that is, in the region where the minimum hot air flow occurs during operation), namely above the impact mechanism.

[0007] It has been found to be advantageous if the cover housing extends in the axial direction along the entire length of the guide tube. Thus, the region of the striking mechanism can be easily cleaned and can also be relatively easily used for visual inspection.

[0008] In a particularly preferred configuration, the main housing and the cover housing are formed in a complementary manner to one another in the radial direction and at least along the guide tube.

[0009] In a further preferred configuration, the end plate is formed integrally with the main housing. Advantageously, therefore, the cutting in the region of the integrated end plate can be performed with relatively rough tolerances, with the result that the cutting volume is significantly reduced.

[0010] It has been found to be advantageous that the main housing has a concave surface portion on which at least one radial rib is formed for radially and / or axially supporting the guide tube. In a particularly preferred configuration, the radial rib is integrally formed as an unmachined portion and / or is formed without cutting.

[0011] In a further preferred embodiment, the cover housing has a retaining lip on the side facing the eccentric. It has been found to be advantageous if the contour of the retaining lip at least partially, preferably completely, follows the circular path of the eccentric point of the eccentric.

[0012] It has been found to be advantageous if the eccentric is rotatably mounted in the end plate by means of a bearing journal comprised by the impact mechanism, said bearing journal being formed so as to rotate jointly with the eccentric and / or being formed separately from the eccentric.

[0013] In a particularly preferred embodiment, the eccentric wheel is configured as an externally toothed gear, which can preferably be driven to rotate by an electric motor included in the handheld power tool. It has been found to be advantageous if the cover housing is screwed together with the main housing. The main housing can be primarily composed of metal. The cover housing can be primarily composed of plastic.

[0014] Further advantages will become apparent from the following description of the accompanying drawings. Various exemplary embodiments of the present invention are illustrated in the accompanying drawings. The drawings, the description, and the claims contain many combined features. Those skilled in the art will readily consider these features individually and combine them to form further useful combinations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In the accompanying drawings, the same and similar parts are denoted by the same reference numerals. In the accompanying drawings:

[0016] Figure 1 A first preferred exemplary embodiment of an impact mechanism of a handheld electric power tool is shown; and

[0017] Figure 2 A second preferred exemplary embodiment of an impact mechanism for a handheld electric power tool is shown in an exploded view. DETAILED DESCRIPTION

[0018] exist Figure 1 A handheld electric power tool 100 is shown in FIG. Figure 2 A first preferred exemplary embodiment of an electropneumatic impact mechanism 70 , for example in the form of a cutting hammer.

[0019] The electropneumatic impact mechanism 70 includes a transmission housing 60 and a guide tube 50, wherein the guide tube 50 is at least partially disposed within the transmission housing 60. The electropneumatic impact mechanism 70 also includes an excitation piston 40 movable in the axial direction AR within the guide tube 50, a connecting rod 30 coupled to the excitation piston 40, and an eccentric 20. The eccentric 20 is coupled to the connecting rod 30 on one side and is rotatably mounted relative to the transmission housing 60 on the other side via an end plate 10 of the transmission housing 60. More precisely, the eccentric 20 is rotatably mounted in the end plate 10 via a bearing journal 25 included in the impact mechanism 70. The bearing journal 25 is formed to rotate co-rotatably with the eccentric 20 and is separate from the eccentric 20. The eccentric 20 is in the form of an externally toothed gear and can be driven in rotation by an electric motor (not shown).

[0020] According to the present invention, the transmission housing 60 is subdivided into at least a main housing 61 and a cover housing 65 separate from the main housing 61, so that the guide tube 50 is at least partially supported on the main housing 61 by the cover housing 65. More precisely, the guide tube 50 has at least one annular retaining collar 51, via which the cover housing 65 is supported on the main housing 61 in a radial direction RR relative to the guide tube 50, the main housing itself also being in contact with the retaining collar 51. The cover housing 65 is screwed together with the main housing 61 ( Figure 1 Screws not shown).

[0021] In the exemplary embodiment shown here, the main housing 61 is constructed from metal, such as die-cast aluminum. Because the end plates 10 are advantageously formed integrally with the main housing 61, they are also constructed from die-cast aluminum. The cover housing 65 is constructed from plastic, such as polybutylene terephthalate (PBT). By making the cover housing 65 from plastic, the overall weight of the transmission housing 60 is significantly reduced.

[0022] from Figure 1 It is also evident in FIG. 1 that the cover housing 65 has a retaining lip 67 on the side facing the eccentric 20, the contour of which at least partially follows the circular path 23 of the eccentric point 21 of the eccentric 20. In this way, the connecting rod 30, the eccentric 20 and the bearing journal 25 are secured against lifting in the radial direction RR ( Figure 1 It should be noted that in the context of this description, the radial direction RR and the axial direction AR are always relative to the guide tube 50 , wherein the axial direction AR is oriented coaxially with the direction of movement of the driving piston 40 .

[0023] A separation cap 71 is optionally provided, which is arranged between the main housing 61 and the cover housing 65 and is coupled at least around the eccentric wheel 20 .

[0024] exist Figure 2 B shows a handheld electric power tool 100 in an exploded view (see Figure 2 A second preferred exemplary embodiment of an electropneumatic impact mechanism 70, for example in the form of a cutting hammer. Figure 1 The main difference of the exemplary embodiment in is the absence of the separation cap 71 .

[0025] from Figure 2 As is evident in Figure B, the cover housing 65 extends in the axial direction AR along the entire length GL of the guide tube 50. The cover housing 65 is constructed, for example, from plastic, thereby significantly reducing weight compared to prior art impact mechanisms. This also allows for relatively easy insertion of the guide tube 50 into the main housing 61 and for easier assembly of the driving piston 40, connecting rod 30, and eccentric 20. The eccentric can also be inserted into the main housing 61 from above (i.e., from the side of the main housing 61 facing away from the end plate 10) through the large opening (i.e., with the cover housing 65 removed). In particular, the complex process of screwing the crankpin 31 into the eccentric 20 and subsequently introducing the driving piston 40 into the guide tube 50 is facilitated.

[0026] It is obvious that the main housing 61 and the cover housing 65 are formed in a complementary manner to each other in the radial direction RR and at least along the guide tube 50. The inner surfaces of the main housing 61 and the cover housing 65 complement each other to form a complete cylindrical body, in which the guide tube 50 is completely received. In particular, due to this complementary construction, the support cover 65 composed of plastic reinforces the main housing 61 of the transmission housing 60 in such a way that the main housing 61 does not become loose due to the screw connection (in the Figure 2 B) and loses rigidity.

[0027] The main housing 61 has a concave surface portion 63 on which are formed, for example, four radial ribs 64 for radially and axially supporting the guide tube 50. Advantageously, the radial ribs 64 are integrally formed on the main housing 61 as an unmachined portion and remain uncut.

[0028] Reference Signs List

[0029] 10 End Plate

[0030] 20 eccentric wheel

[0031] 21 Eccentric Point

[0032] 23 Circular Path

[0033] 25 Support journal

[0034] 30 connecting rod

[0035] 31 crankpin

[0036] 40 Inspiring Piston

[0037] 50 guide tube

[0038] 51 Retention ring

[0039] 60 transmission housing

[0040] 61 main housing

[0041] 62 threaded holes

[0042] 63 concave surface portion

[0043] 64 radial ribs

[0044] 65 cover housing

[0045] 67 Retention lip

[0046] 70 Impact mechanism

[0047] 71 Separation Cap

[0048] 100 Handheld Electric Power Tools

[0049] AR axial direction

[0050] GL entire length

[0051] RR radial direction

Claims

1. A handheld electric power tool (100), comprising an electro-pneumatic impact mechanism (70), the electro-pneumatic impact mechanism comprising a transmission housing (60), a guide tube (50) at least partially arranged in the transmission housing (60), an excitation piston (40) movable in an axial direction (AR) in the guide tube (50), a connecting rod (30) connected to the excitation piston (40), and an eccentric (20), the eccentric being connected on one side to the connecting rod (30) and being rotatably mounted relative to the transmission housing (60) via an end plate (10) of the transmission housing (60) on the other side, It is characterized by: The transmission housing (60) is subdivided into at least a main housing (61) and a cover housing (65) separated from the main housing (61), so that the guide tube (50) is at least partially supported on the main housing (61) by the cover housing (65), and the main housing (61) and the cover housing (65) are formed in a complementary manner to each other in a radial direction (RR) and at least along the guide tube (50).

2. The handheld electric power tool (100) according to claim 1, It is characterized by: The cover housing (65) extends in the axial direction (AR) along the entire length (GL) of the guide tube (50).

3. The handheld electric power tool (100) according to any one of the preceding claims, It is characterized by: The main housing (61) is made of metal and / or the cover housing (65) is made of plastic.

4. The handheld electric power tool (100) according to claim 1 or 2, It is characterized by: The end plate (10) is formed integrally with the main housing (61).

5. The handheld electric power tool (100) according to claim 1 or 2, It is characterized by: The main housing (61) has a concave surface portion (63) on which at least one radial rib (64) is formed for radially and / or axially supporting the guide tube (50).

6. The handheld electric power tool (100) according to claim 5, It is characterized by: The radial rib (64) is formed integrally as an unmachined part and / or is formed without cutting.

7. The handheld electric power tool (100) according to claim 1 or 2, It is characterized by: The cover housing (65) has a retaining lip (67) on the side facing the eccentric (20), the contour of which at least partially follows the circular path (23) of the eccentric point (21) of the eccentric (20).

8. The handheld electric power tool (100) according to claim 1 or 2, It is characterized by: The cover shell (65) is screwed together with the main shell (61).

9. The handheld electric power tool (100) according to claim 1 or 2, It is characterized by: The eccentric wheel (20) is rotatably mounted in the end plate (10) via a bearing journal included in the electro-pneumatic impact mechanism (70), wherein the bearing journal is formed to rotate together with the eccentric wheel (20) and / or is formed separately from the eccentric wheel.

10. The handheld electric power tool (100) according to claim 1 or 2, characterized in that: The handheld electric power tool is a hammer drill and / or a cutting hammer.

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