EP-4741106-A1 - 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.

Inventors

• Knyrim, Maximilian

Assignees

• Hilti Aktiengesellschaft

Dates

Publication Date

20260513

Application Date

20241111

Claims (10)

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 in 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 in that the gel filling consists of a dimensionally stable silicone material, silicone rubber, rubber or elastomer with a density in the range between 0.5 and 2 g/cm 3 .
3. Electric hand tool according to one of the preceding claims, characterized in that the 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 in 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 in 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 in 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 projecting core anchor part (6).
7. Electric hand tool according to one of the preceding claims, characterized in 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 in 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 in 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 in that the side handle (5) is provided with a cover sleeve (14) in the area of the metal band mechanism.

Description

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. 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 From the EP 1 319 477 A1 This describes a generic electric hand tool for striking a workpiece at least partially axially, equipped with an integrated impact mechanism. A side handle, detachably attached to the machine housing, features an integrated, flat force sensor between at least two mutually associated pressure surfaces, oriented at least partially transversely to the impact axis, for the non-slip detection of the force applied by the user towards the workpiece. The clamping force exerted on the workpiece is measured. During machining, in addition to the clamping force itself, the force sensor also records the vibration load transmitted back from the tool. The sensor signals are fed to an integrated control unit for evaluating performance parameters, which, among other things, also performs active vibration reduction based on these parameters. From the JP 2017 164 825 A2 In contrast, a passive method for vibration decoupling of a side handle of a power tool emerges. In this technical solution, a side handle core is surrounded by a handle housing part arranged radially apart 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. 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 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. 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. 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. 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 whose compliance for vibration decoupling is adjusted by introducing small gas bubbles. This has the advantage that the actuating torques can be reliably transmitted via the gel filling. 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 a