Electric hand tool with a vibration-decoupled side handle

Abstract

Electric hand tool comprising a machine housing (1) with a handle section (2) integrally formed therein and a tool holder (3) projecting from the machine housing (1), to which a side handle (5) detachably attached to a device neck (4) of the machine housing (1) is arranged adjacent, the side handle being provided with means for vibration decoupling, the means for vibration decoupling comprising a gel filling of a handle interior (8) formed between a core anchor part (6) of the side handle (5) fixed to the machine housing (2) and a handle housing part (7) surrounding it.

Description

[0001] The present invention relates to an electric hand tool comprising a machine housing with a handle section molded onto it and a tool holder projecting from the machine housing, to which a side handle detachably attached to a device neck of the machine housing is arranged adjacent, the side handle being equipped with means for vibration decoupling.

[0002] The scope of application of the invention extends to power tools, such as, in particular, impact drills, rotary hammers, or demolition hammers. Such power tools perform at least partially axial impact machining of a workpiece with a tool, for example, an impact drill or chisel, which is detachably clamped in the tool holder. In particular, higher-performance power tools are equipped, in addition to the obligatory handle section of the machine housing, with a side handle that can be detachably attached to a neck of the machine housing and pivoted accordingly, for improved handling. The present invention addresses vibration decoupling of the machine vibrations transmitted to the operator via such a side handle. State of the art

[0003] EP 1 319 477 A1 discloses a generic electric hand tool for applying at least partial axial impact to a workpiece with an integrated impact mechanism. A side handle, detachably attached to the machine housing, has an integrated flat force sensor between at least two corresponding pressure surfaces, oriented at least partially transversely to the impact axis, for the sliding-free detection of the contact force exerted by the user towards the workpiece. During workpiece processing, the force sensor also records the vibration load transmitted back from the tool, in addition to the pure contact force. The sensor signals are fed to an integrated control unit for evaluating the performance parameters, which, among other things, also performs active vibration reduction based on these parameters.

[0004] In contrast, JP 2017 164 825 A2 discloses a passive method for vibration decoupling of a side handle of a power tool. In this technical solution, a side handle core is surrounded by a handle housing part arranged radially spaced from it, with the connection between the side handle core and the handle housing part being achieved via elastomeric O-rings for vibration decoupling. The effectiveness of such passive vibration decoupling depends on the material properties and the geometric relationships of the components contributing to the vibration decoupling.

[0005] The object of the present invention is to further improve a generic electric hand tool with means for vibration decoupling in such a way that effective vibration decoupling can be achieved using passive technical means. Disclosure of the invention

[0006] The problem is solved starting from an electric hand tool according to the preamble of claim 1 in conjunction with its characterizing features. The following dependent claims describe advantageous embodiments of the invention.

[0007] The invention includes the technical teaching that the means for vibration decoupling comprise a gel filling of a handle interior formed between a core anchor part of the side handle fixed to the machine housing and a handle housing part surrounding it.

[0008] In other words, the solution according to the invention is based on a side handle that is vibration-decoupled by means of a gel filling. A low-viscosity, gel-like to jelly-like viscous substance, preferably silicone, is located between the core anchor part attached to the device and the handle housing part gripped by the user. This gel filling dampens the device vibrations transmitted to the user with a high damping rate and low spring rate.

[0009] Preferably, the gel filling used in this application consists of a dimensionally stable silicone material, silicone rubber, rubber, or elastomer with a density in the range of 0.5 to 2 g / cm³. This density range ensures an optimum balance between dimensional stability and damping properties. A dimensionally stable or gel-like material, such as that used, for example, in bicycle saddles with gel padding, is preferably suitable as the gel filling. In particular, a soft silicone rubber with a hardness of < 30 Shore A is suitable. In this context, it is also conceivable to use, for example, a harder silicone material, the compliance of which is adjusted for vibration decoupling by introducing small gas bubbles. This has the advantage that the actuating torques can be reliably transmitted via the gel filling.

[0010] According to a further improvement of the invention, it is proposed that the core anchor part be essentially pin-shaped and provided with a ribbed, knurled, or otherwise contoured surface structure. For example, a significant roughening, undercuts, or the like can also be used to achieve a form-fitting increase in the surface area of ​​the component. This allows the gel filling to adhere better to the adjacent component and prevents unwanted detachment when the gel filling is subjected to stress against the housing. Preferably, the gel filling should completely surround the core anchor part to achieve a functional damping effect.

[0011] Similarly, it is proposed that the handle housing part also be provided on the inner wall side with a ribbed, knurled or similar surface structure to achieve the aforementioned advantages.

[0012] According to a preferred embodiment of the invention, the handle housing part further comprises a hollow plastic body which has an end-face insertion opening for receiving the core armature part with clearance. The insertion opening is dimensioned much larger than the local cross-section of the core armature part in order to maintain sufficient freedom of movement for vibration damping.

[0013] To prevent the gel filling from oozing out of the handle's interior, a further improvement to the invention proposes that the handle housing part, in the area of ​​the end-face insertion opening, has a radially inwardly extending edge region against which a type of washer rests on the inside of the housing to seal against the protruding core anchor part. The washer is dimensioned in relation to the adjacent components such that the aforementioned clearance is still sufficiently maintained.

[0014] The attachment and detachment of the side handle to the machine housing neck is preferably achieved via an actuating mechanism by rotating the handle housing part in one direction to clamp it and in the opposite direction to release it. The torque for attaching the handle is transmitted entirely via the vibration-damping gel filling. Thanks to the surface structuring, sufficiently high torques can be transmitted. For sufficiently reliable torque transmission on the one hand and significant vibration damping on the other, the radial distance between the core anchor part and the handle housing part should be at least 5 mm. The greater the distances between these components, the more attention must be paid to ensuring a correspondingly sufficient shear strength in the gel filling.

[0015] According to a further improvement of the invention, it is proposed that the detachable fastening of the side handle to the device neck is effected by a metal band mechanism, which can be tensioned by a pull screw when the handle is rotated and which interacts with an internal thread of the core anchor part. Preferably, the internal thread of the core anchor part is formed by a metal threaded sleeve that is firmly connected to the core anchor part. The pull screw should accordingly also be made of metal. In contrast, the core anchor part itself can, for example, be manufactured as an injection-molded plastic part.

[0016] In order to achieve the most homogeneous grip surface possible, a further measure improving the invention proposes that the side handle in the area of ​​the metal band mechanism, in particular at the level of the pull screw with metal threaded sleeve, be surrounded by an outer cover sleeve, which ensures a uniform transition to the handle housing part on the one hand and to the metal band of the metal band mechanism on the other. Detailed description based on drawing

[0017] 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 is a schematic side view of an electric hand tool with a side handle attached to it, Fig. 2 is a longitudinal section of the side handle with a gel filling for vibration decoupling, and Fig. 3 is a cross-sectional view of the side handle along section AA. Fig. 2 .

[0018] According to Fig. 1 An electric hand tool, shown here as an example of a rotary hammer, essentially consists, with regard to its external structure, of a machine housing 1 with a handle section 2 molded onto it. A tool holder 3 for a tool (not shown) protrudes from the machine housing 1. In the area between the tool holder 3 and the machine housing 1 is a so-called tool neck 4 with a cylindrical shape, to which a side handle 5 can be attached at the desired angle relative to the longitudinal axis of the tool.

[0019] According to Fig. 2A handle interior 8 is formed between a core anchor part 6 of the side handle 5, which can be fixedly attached to the machine housing (not shown further), and a handle housing part 7 surrounding it, and this interior is filled with a gel filling.

[0020] The gel filling of the handle interior 8 surrounds the core anchor part 6 and consists of a dimensionally stable silicone material, in this case silicone rubber. To prevent the gel filling from oozing out of the handle interior 8, the handle housing part 7 is provided with a radially inwardly extending edge in the area of ​​an end-face insertion opening 9. A washer 10 rests against this edge on the inside of the housing to seal against the protruding core anchor part 6. Within the handle interior 8, there is a minimum radial gap of approximately 5 mm between the core anchor part 6 and the handle housing part 7.

[0021] The detachable attachment of the side handle 5 to the neck of the machine housing (not shown) is achieved by a metal band mechanism. The metal band 11 can be tensioned by a tension screw 12, which engages with an internal thread of the core anchor part 6. The internal thread of the core anchor part 6 is formed by a metal threaded sleeve 13, which is overmolded with the plastic material of the core anchor part 6. Furthermore, the side handle 5 is provided with a plastic cover sleeve 14 in the area of ​​the metal band mechanism described above.

[0022] According to Fig. 3 The pin-shaped core anchor part 6 has a ribbed surface structure 15, which increases the surface area for the positive locking interaction of the gel filling present in the handle interior 8. Similarly, the handle housing part 7 is also provided with a ribbed surface structure 16 on its inner wall.

[0023] The invention is not limited to the preferred embodiment described above. Variations thereof are also conceivable and are included within the scope of protection of the following claims. For example, it is conceivable to use a different fastening mechanism for the side handle on the machine housing instead of the exemplary metal band mechanism. Furthermore, a different surface structuring of the handle housing part and / or the core armature part may also be considered, which ensures sufficient torque transmission stability through positive locking. Reference symbol list

[0024] 1 Machine housing 2 Handle section 3 Tool holder 4 Device neck 5 Side handle 6 Core armature part 7 Handle housing part 8 Handle interior 9 Insertion opening 10 Washer 11 Metal band 12 Draw screw 13 Metal threaded sleeve 14 Cover sleeve 15 Surface texture, core side 16 Surface texture, housing side

Claims

1. Electric hand tool comprising a machine housing (1) with a handle section (2) molded onto it and a tool holder (3) projecting from the machine housing (1), to which a side handle (5) is arranged adjacent and detachably attached to a device neck (4) of the machine housing (1), the side handle being provided with means for vibration decoupling, characterized by the fact that The means for vibration decoupling comprise a gel filling of a handle interior (8) formed between a core anchor part (6) of the side handle (5) fixed to the machine housing (2) and a handle housing part (7) surrounding it.

2. Electric hand tool according to claim 1, characterized by the fact that The gel filling consists of a dimensionally stable silicone material, silicone rubber, rubber or elastomer with a density in the range of 0.5 to 2 g / cm³. 3 consists.

3. Electric hand tool according to one of the preceding claims, characterized by the fact thatthe core anchor part (6) is pin-shaped and is provided with a ribbed or knurled surface structure (15).

4. Electric hand tool according to one of the preceding claims, characterized by the fact that the handle housing part (7) is designed as a hollow body made of plastic, which has an end-face insertion opening (9) for receiving the core anchor part (6).

5. Electric hand tool according to claim 4, characterized by the fact that the handle housing part (7) is provided on the inner wall side with a ribbed or knurled surface structure (16).

6. Electric hand tool according to claim 4 or 5, characterized by the fact that The handle housing part (7) has a radially inward extending edge area in the area of ​​the end-face insertion opening (9), against which a washer (10) comes to rest on the inside of the housing for sealing against the protruding core anchor part (6).

7. Electric hand tool according to one of the preceding claims, characterized by the fact that the radial distance between core anchor part (6) and handle housing part (7) is at least 5 mm.

8. Electric hand tool according to one of the preceding claims, characterized by the fact that The detachable fastening of the side handle (5) to the device neck (4) is effected by a metal band mechanism which can be tensioned by a tension screw (12) which interacts with an internal thread of the core anchor part (6).

9. Electric hand tool according to one of the preceding claims, characterized by the fact that the internal thread of the core anchor part (6) is formed by a metal threaded sleeve (13) which is firmly connected to the core anchor part (6).

10. Electric hand tool according to one of the preceding claims, characterized by the fact that The side handle (5) is provided with a cover sleeve (14) in the area of ​​the metal band mechanism.

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