Power tool with detachably connected housing parts of a pneumatic striking mechanism

Abstract

Power tool with a pneumatic impact mechanism (3) for rear actuation of a tool, the drive components of which are housed in a motor-side gearbox housing part (8) and a tool-side guide housing part (9) detachably attached thereto, wherein the guide housing part (9) is inserted into or onto a corresponding pipe receiving section (11) of the gearbox housing part (8) with an end-side connecting pipe section (10) and is secured with a pipe clamp (12).

Description

[0001] The present invention relates to an electric tool with a pneumatic impact mechanism for rear-actuating a tool, the drive components of which are housed in a motor-side gearbox housing part and a tool-side guide housing part detachably attached thereto.

[0002] The application area of ​​the invention extends primarily to handheld power tools, such as, in particular, rotary hammers, demolition hammers, and the like. A common feature of this type of power tool is a pneumatic impact mechanism for applying impact energy to the tool, for example, a hammer drill, chisel drill, or chisel. Such a pneumatic impact mechanism must be functionally integrated within the housing components of the power tool, together with the preceding gear components and the subsequent tool holder components (viewed in the direction of power flow). For this purpose, the housing components are designed in two parts and, in the case of this invention, comprise a motor-side gear housing part and a tool-side guide housing part, which are detachably connected to one another. State of the art

[0003] WO 2021 / 198023 A1 describes a power tool with a pneumatic impact mechanism, driven by an electric motor. The motor's rotary motion is converted via an eccentric drive into an alternating linear motion of an exciter piston of the pneumatic impact mechanism. The exciter piston is dynamically sealed within a guide tube and, via an internal column of compressed air, acts on an opposing impact piston. This impact piston acts in the direction of action on a coaxial impactor, whose mass-related impact energy is then transferred coaxially to the tool, which is detachably mounted in a tool holder. In this prior art design, a gearbox housing completely accommodates the guide tube and is longitudinally divided into a main shell and a cover shell.

[0004] The housing designs of interest here also emerge from the general state of the art, in which a gearbox housing accommodating the pneumatic impact mechanism is transversely divided and thus consists of a motor-side gearbox housing part and a tool-side guide housing part. Within the guide housing part are the guide tube of the pneumatic impact mechanism and a hammer, to which a tool holding unit is attached at the distal end. The eccentric drive, to which an electric motor is flanged, is located in the motor-side gearbox housing part.

[0005] The guide housing part is usually detachably attached to the gearbox housing part via a flanged screw connection. This requires several screw points spaced apart along the circumference, which in turn require a corresponding amount of installation space.

[0006] It is therefore the object of the present invention to further improve an electric tool of the type described above in such a way that, in the case of a transversely divided gearbox housing, the detachable fastening of a guide housing part to a gearbox housing part is realized in a space-saving and reliable manner using simple technical means. Disclosure of the invention

[0007] The problem is solved starting from a power tool according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims describe advantageous embodiments of the invention.

[0008] The invention includes the technical teaching that the guide housing part is inserted into or onto a corresponding pipe receiving section of the gearbox housing part with an end-side connecting pipe section and is secured with a pipe clamp.

[0009] The advantage of the solution according to the invention lies particularly in the fact that such a pipe clamp can be attached to the connection point from the outside in a space-saving manner, without requiring receiving or threaded holes for screws on a gearbox housing component. Since a conventional flange fastening for attaching screws, especially in the radial direction, requires a corresponding amount of installation space, the pipe clamp solution according to the invention can be implemented in a more space-saving way.

[0010] Compared to the prior art, simplified assembly results from the fact that, after inserting or attaching the corresponding pipe connection sections, the pipe clamp simply needs to be placed at the connection point and secured with preferably a single clamping screw, whereby the radially inward clamping forces are distributed evenly around the circumference. This also results in greater connection reliability compared to a flange fastening, since with a flange fastening, it is necessary to ensure that all flange screws are tightened to the same torque.

[0011] According to a preferred embodiment of the invention, the connecting pipe section of the guide housing part is inserted into the corresponding pipe receiving section of the gearbox housing part to a defined insertion depth. This defined insertion depth is preferably achieved at a housing stop formed between the gearbox housing part and the guide housing part. Such a housing stop can, for example, be designed in the form of a housing shoulder extending radially outwards, which abuts the edge region of the pipe receiving section. This ensures a sufficiently large overlap of the components to be connected to each other via the pipe clamp.

[0012] According to a preferred embodiment of the pipe clamp, it is designed as a slotted ring with radially outward-extending screw tongues at both ends. The screw tongues have openings for receiving a clamping screw. Preferably, one of the openings is a threaded hole so that the clamping screw, preferably a machine screw, can be screwed directly into it. An additional nut is therefore unnecessary.

[0013] According to a preferred embodiment, the pipe clamp is designed to axially secure the guide housing part against the gearbox housing part and, in particular, pulls the guide housing part against the gearbox housing part in an axial direction when fixing it.

[0014] In a structurally simple embodiment, the pipe clamp for axially securing the guide housing part to the gearbox housing part is designed with wall sections at each end that are angled radially inwards, with a first wall section interacting with the guide housing part and a second wall section interacting with the gearbox housing part. This allows the guide housing part to be easily clamped axially to the gearbox housing part.

[0015] Preferably, the pipe clamp for the application relating to the invention is made of a sheet steel consisting of a stamped and bent part in order to enable efficient production without impairment of quality.

[0016] According to a specific design variant, it is proposed that the pipe clamp be designed as a hinged pipe clamp with a toggle screw to ensure easy installation. In such a hinged pipe clamp, the pipe clamp and clamping screw form a pre-assembled, captive unit.

[0017] According to a further improvement of the invention, it is proposed that the guide housing part and / or the gearbox housing part be / are made of a cast light metal material. This allows sufficient housing stability to be achieved while simultaneously minimizing weight.

[0018] According to a preferred embodiment of the invention, the pneumatic impact mechanism has a guide tube housed in the guide housing part for receiving a known impact piston-exciter piston combination. On the side of the gearbox housing part, at least the eccentric drive that drives the pneumatic impact mechanism is housed therein for converting a rotary drive movement into a linear alternating movement for the pneumatic impact mechanism. The rotary drive movement is generated by an electric motor, preferably also detachably attached to the gearbox housing part, the axis of rotation of which is preferably aligned perpendicular to the impact axis of the pneumatic impact mechanism. Detailed description based on drawing

[0019] Further measures improving the invention are described in more detail below, together with a description of a preferred embodiment of the invention, with reference to the figures. The figures show: Fig. 1 a schematic, partially cut-away side view of a power tool, here in the form of a rotary hammer, Fig. 2 an exploded view of housing parts in conjunction with a pipe clamp, Fig. 3 a perspective view of the gearbox parts in the assembled state, and Fig. 4 a detailed view of a pipe clamp with connecting screw as housing connecting means.

[0020] According to Fig. 1 A power tool designed in the form of a rotary hammer essentially consists of an electric motor 1, whose rotary motion is transmitted via an eccentric drive 2 into a linear alternating working motion on a pneumatic impact mechanism 3. The pneumatic impact mechanism 3 acts on a striker 4, whose impact mass in turn acts backward on a tool 6 clamped in a tool holder 5.

[0021] The aforementioned drive components, including the pneumatic impact mechanism 3, are housed in a machine casing 7. The eccentric drive 2 is located within a gearbox housing part 8, to which a guide housing part 9, which accommodates the pneumatic impact mechanism 3, is detachably attached.

[0022] According to Fig. 2 The guide housing part 9, with its end-end connecting pipe section 10, is inserted into a corresponding pipe receiving section 11 of the gearbox housing part 8 and secured by a pipe clamp 12 with a clamping screw 13. The insertion depth of the connecting pipe section 11 of the guide housing part 9 into the gearbox housing part 8 is defined by a housing stop 15 extending radially outwards.

[0023] From the Fig. 3The assembled state of the components described above is shown. The pipe clamp 12 surrounds the gearbox housing part 8 at the connection point where the guide housing part 9 is inserted.

[0024] According to Fig. 4 The pipe clamp 12 is manufactured as a stamped and bent steel part and has screw tongues 14a and 14b at its ends. The screw tongue 14a is provided with a threaded bore, so that the clamping screw 13 is inserted through a through-hole in the opposite screw tongue 14b in order to be screwed into the aforementioned threaded bore of the screw tongue 14a.

[0025] The invention is not limited to the preferred embodiment described above. Rather, variations thereof are also conceivable, which are included in the scope of protection of the following claims. For example, it is also possible that the guide housing part is provided with such a connecting pipe section that can be attached to a pipe receiving section of the gearbox housing part. Preferably, such an attachment area is provided with longitudinal slots so that the radially inward-acting fastening force of the pipe clamp is optimally effective. Instead of a pipe clamp, a snap ring can also be used in conjunction with an interference fit. A screw connection between the two housing parts is also conceivable. Reference symbol list

[0026] 1 Electric motor 2 Eccentric drive 3 Pneumatic impact mechanism 4 Dipper 5 Tool holder 6 Tool 7 Machine housing 8 Gearbox housing part 9 Guide housing part 10 Connecting pipe section 11 Pipe mounting section 12 Pipe clamp 12a,b Wall area of ​​the pipe clamp 13 Tensioning screw 14 Screw tongue 15 Housing stop

Claims

1. Power tool with a pneumatic impact mechanism (3) for rear actuation of a tool, the drive components of which are housed in a motor-side gearbox housing part (8) and a tool-side guide housing part (9) detachably attached thereto, characterized by the fact that the guide housing part (9) is inserted into or onto a corresponding pipe receiving section (11) of the gearbox housing part (8) with an end-side connecting pipe section (10) and is secured with a pipe clamp (12).

2. Power tool according to claim 1, characterized by the fact that the connecting pipe section (10) of the guide housing part (9) is inserted into the pipe receiving section (11) of the gearbox housing part (8) with a defined insertion depth.

3. Power tool according to claim 2, characterized by the fact that The insertion depth is defined by a housing stop (15) formed between the gearbox housing part (8) and the guide housing part (9).

4. Power tool according to one of the preceding claims, characterized by the fact that the pipe clamp (12) is designed in the form of a slotted ring, which is provided with end-end corresponding and radially outward extending molded screw tongues (14a, 14b) which are provided with openings that can be aligned with each other for receiving a clamping screw (13).

5. Power tool according to one of the preceding claims, characterized by the fact that the pipe clamp (12) is designed to axially secure the guide housing part (9) relative to the gearbox housing part (8).

6. Power tool according to claim 5, characterized by the fact thatThe pipe clamp (12) for axially securing the guide housing part (9) relative to the gearbox housing part (8) is designed at its ends with wall areas (12a, 12b) that are inclined inwards in a radial direction, wherein a first wall area (12a) is designed to interact with the guide housing part (9) and a second wall area (12b) is designed to interact with the gearbox housing part (8).

7. Power tool according to one of the preceding claims, characterized by the fact that the pipe clamp (12) is made from a sheet of steel as a stamped and bent part.

8. Power tool according to one of the preceding claims, characterized by the fact that the pipe clamp (12) is designed as a hinged pipe clamp with a clamping screw (13) designed as a toggle screw.

9. Power tool according to one of claims 4 to 8, characterized by the fact thatthe clamping screw (13) is designed as a machine screw which extends through the opening of one screw tongue (14b) in order to be screwed into an opening of the other screw tongue (14a) which is provided with a corresponding thread.

10. Power tool according to one of the preceding claims, characterized by the fact that the guide housing part (9) and / or the gearbox housing part (8) is / are made of a cast light metal material.

11. Power tool according to one of the preceding claims, characterized by the fact that the pneumatic percussion mechanism (3) comprises a guide tube housed in a guide housing part (9) for receiving a percussion piston-excitation piston combination.

12. Power tool according to one of the preceding claims, characterized by the fact thatthe pneumatic percussion mechanism (3) comprises an eccentric drive housed in the gearbox housing part (8) for converting a rotating electromotive drive movement into a linear alternating movement to drive the pneumatic percussion mechanism.

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