Machine tool with coupleable operating-mode-selection rotary knob

Abstract

The invention relates to a machine tool, in particular a combination hammer, having a housing (5), an assembly (9) comprising a percussion mechanism device (11) and a drive device, the assembly (5) being provided at least partly within the housing (5) and mounted so as to be movable relative to the housing (5), and a rotary knob (60) for selecting the operating mode of the machine tool, the rotary knob being operatively connected to the assembly (9). The machine tool is characterized in that a shaft (61) with a non-circular outer cross section is rotationally fixed to the rotary knob (60), the shaft (61), together with the rotary knob (60), is movably mounted on the housing (5), and the assembly (9) is equipped with a coupling sleeve (70) into which the shaft (61) can be inserted, thereby establishing a rotationally-fixed connection between the shaft (61) and the coupling sleeve (70).

Description

[0001] - 1 - 2023PF00245

[0002] Hilti Aktiengesellschaft in Schaan

[0003] Principality of Liechtenstein

[0004] Machine tool with connectable operating mode selection knob

[0005] The invention relates to a machine tool, in particular a combination hammer, according to the preamble of claim 1. Such a machine tool is equipped with a housing, with an assembly comprising a striking mechanism and a drive mechanism, wherein the assembly is at least partially arranged inside the housing and is movably arranged relative to the housing, and with a rotary knob for selecting the operating mode of the machine tool, which is operatively connected to the assembly.

[0006] EP4331774 A1 describes a machine tool with a housing having a grip area and an assembly comprising a percussion device and a drive device, wherein the assembly is substantially arranged inside the housing and is movable relative to the housing.

[0007] The object of the invention is to provide a machine tool that is particularly low-maintenance and vibration-free for the user, with particularly low effort and particularly good usability.

[0008] The problem is solved according to the invention by a machine tool having the features of claim 1. Preferred embodiments are specified in the dependent claims.

[0009] A machine tool according to the invention is characterized in that a shaft with a non-circular outer cross-section is arranged in a rotationally fixed manner on the rotary knob, that the shaft together with the rotary knob is arranged on the housing in a displaceable manner, in particular axially displaceable with respect to the axis of the shaft, and that a coupling sleeve is arranged on the assembly into which the shaft can be inserted, in particular axially displaceable with respect to the axis of the shaft, thereby establishing a rotationally fixed connection between the shaft and the coupling sleeve. The invention relates to a machine tool in which the assembly with impact mechanism is arranged movably within the housing for low-vibration operation. In such machine tools, the operating mode selector switch could be attached to the impact mechanism, so that it would follow the movement of the assembly.To decouple the switch from the housing, a comparatively large opening in the housing is usually required, which in turn must be elaborately sealed against dust and particles, whereby the sealing itself can again cause an undesirable coupling between the housing and the assembly.

[0010] This invention addresses this issue by providing a rotary knob for selecting the operating mode, which is mounted on the housing of the machine tool and can be decoupled from the impact mechanism as long as it is not being operated by the user. During impact operation of the machine tool, the assembly containing the impact mechanism can move freely within the machine tool, while the rotary knob remains stationary on the housing. The knob is only coupled to the assembly during mode selection. This concept allows for a particularly simple sealing mechanism and counteracts mechanical vibration transmission.

[0011] It is particularly advantageous that a compression spring is provided which forces the shaft out of the coupling sleeve. Specifically, the compression spring can act against the housing on one side and against the rotary knob and shaft on the other. This allows for a particularly simple automatic disengagement and further improves operation.

[0012] The compression spring can, for example, be a coil spring, which can be advantageous in terms of design complexity. The coil spring can preferably rotate around the shaft.

[0013] To further reduce the design effort, the shaft with a non-circular cross-section could, for example, be a multi-sided shaft, in particular a square shaft. Alternatively, the shaft could, for example, be a polygonal shaft or a splined shaft.

[0014] The invention is explained in more detail below with reference to preferred embodiments, which are schematically illustrated in the accompanying figures. Individual features of the embodiments described below can, in principle, be implemented individually or in any combination within the scope of the invention. The figures schematically show: Fig. 1 a highly simplified side sectional view of a first embodiment of a machine tool in the machine tool's rest position;

[0015] Fig. 2 shows a sectional view of the machine tool according to Fig. 1 with a cutting plane perpendicular to the transverse direction X, in the area of ​​the gear selector knob, with the gear selector knob disengaged;

[0016] Fig. 3 is a sectional view AA according to Fig. 2; the viewing axis of Fig. 3 thus corresponds to the viewing axis of Fig. 1;

[0017] Fig. 4 shows a view analogous to Fig. 2, with the gear selector knob engaged; and

[0018] Fig. 5 is a sectional view AA according to Fig. 4, i.e. a view analogous to Fig. 3.

[0019] The figures show a first embodiment of a machine tool 1, which in this case is designed as a combination hammer. The machine tool 1 is shown as an example of a cordless machine tool with a battery 3, but in an alternative embodiment it can also be designed for mains operation.

[0020] The machine tool 1 is designed here in an angled configuration and has a housing 5 which features a rear, user-accessible D-shaped grip area 7. The housing 5, which can be made of one or more parts, is shown here divided longitudinally Z and designed in a so-called cup-shaped construction. Alternatively, the housing 5 can also have, in particular, two housing halves that can be joined together in the transverse direction X and be designed in a so-called shell-shaped construction.

[0021] Within the housing 5, an assembly 9 is arranged, comprising a conventionally designed percussion mechanism 11 and a drive unit 13 designed as an electric motor, which is configured to drive the percussion mechanism 11. The assembly 9 is L-shaped in this case.

[0022] The machine tool 1, in particular its impact mechanism 11, has a tool holder in a conventionally known manner, via which a tool 17, for example a chisel or the like, can be detachably connected to the impact mechanism 11. By means of the assembly 9, chisel operation is possible in this case, wherein a tool 17 held in the impact mechanism 11 is moved back and forth in an oscillating motion in the direction of an impact 19. Alternatively, hammer drilling operation is possible by means of the assembly 9, in which the tool 17 additionally performs a rotary motion.

[0023] The figures also show a longitudinal direction Z, a vertical direction Y, and a transverse direction X. X, Y, and Z are axes of a Cartesian coordinate system and are mutually perpendicular. The longitudinal direction Z extends in the direction of impact 19 without the influence of an external force.

[0024] The assembly 9 can have a separate inner housing 21, which in particular encloses the percussion device 11 and the drive device 13, or within which the percussion device 11 and the drive device 13 are in particular arranged almost completely or completely.

[0025] An example of a front grip area 27 or side handle is shown, which can be detachably connected to the housing 5, for example, by means of a tension band. In this case, the front grip area 27 extends essentially in the transverse direction X, but can be continuously adjusted in the circumferential direction relative to the longitudinal direction Z on the housing 5.

[0026] The assembly 9 is mounted so as to be displaceable relative to the housing 5, in particular in the longitudinal direction Z, in the transverse direction X and in the vertical direction Y. Conventional decoupling devices, not described in detail, may be provided between the assembly 9 and the housing 5 to decouple vibrations generated during operation from the housing 5. These decoupling devices may include springs and / or dampers.

[0027] To select the operating mode (here chiseling or hammer drilling), the machine tool 1 has a rotary knob 60, which is arranged on the housing 5 in a way accessible to an operator. A shaft 61 is fixedly mounted on the rotary knob 60 and projects from the rotary knob 60 into the housing 5. In the present embodiment, the rotary knob is rotatable about the transverse direction X, and the shaft 61 extends in the transverse direction X.

[0028] A coupling sleeve 70 is arranged on the assembly 9, in particular on the impact mechanism 11 thereof. This coupling sleeve 70 is operatively connected to the assembly 9, in particular mechanically, such that the rotational position of the coupling sleeve 70 determines the operating mode (here chisel operation or hammer drilling operation, potentially also rotary drilling operation). The rotary knob 60 and the shaft 61 are arranged to be axially displaceable relative to the housing 5 (with respect to the axis of the shaft 61), such that the shaft 61 can be inserted into and removed from the coupling sleeve 70. In particular, the shaft 61 is inserted into the coupling sleeve 70 when the rotary knob 60 is pressed against the housing 5.

[0029] The shaft 61 has a non-circular outer cross-section, at least in the region of its free end, meaning an outer cross-section that deviates from a circular shape. The coupling sleeve 70 has an inner cross-section corresponding to the non-circular outer cross-section of the shaft 61. Thus, a rotationally fixed connection is established between the shaft 61 and the coupling sleeve 70 when the shaft 61 is inserted into the coupling sleeve. This rotationally fixed connection means that turning the rotary knob 60 causes a corresponding rotation of the coupling sleeve 70 and thus a change in operating mode. Conversely, when the shaft 61 is pushed out of the coupling sleeve 70, the rotationally fixed connection is released, which means that no significant vibrations can be transmitted between the assembly 9 and the rotary knob 60, and thus the housing 5, via the now free shaft 61.

[0030] In the present embodiment, the shaft 61 is directly connected to the rotary knob 60. However, in a modified embodiment, an indirect connection between the shaft 61 and the rotary knob 60 can also be provided, in particular via one or more intermediate pieces, which may have a round or non-round cross-section. Additionally or alternatively, the shaft 61 can also be equipped with an extension.

[0031] In the present embodiment, the shaft 61 has a substantially square cross-section and is therefore a polygonal shaft designed as a square shaft. However, other configurations, such as a polygonal shaft or splined shaft, are also possible.

[0032] The machine tool also features a compression spring 69, which pushes the shaft 61 out of the coupling sleeve 70. In the resting state, i.e., without operator intervention, the compression spring 69 ensures that the shaft 61 is disengaged from the coupling sleeve. The compression spring 69 is a coil spring that surrounds the shaft 61. The compression spring 69 acts against the rotary knob 60 on one side and against the housing 5 on the other. Specifically, the compression spring 69 is located between the housing 5 and the rotary knob 60. To change the operating mode, the drive unit is stopped. The rotary knob 60 is then pressed axially into the housing 5, thereby engaging the shaft 61 in the coupling sleeve 70. The pressed rotary knob 60 is then rotated. This rotation is followed by the rotating coupling sleeve 70, which effects the change in operating mode.Finally, the rotary knob 60 is released, and the compression spring 69 causes the shaft 61 to be withdrawn from the coupling sleeve 70 and disengaged.

Claims

PATENT CLAIMS 1. Machine tool (1), in particular combination hammer, with a housing (5), an assembly (9) comprising a percussion mechanism (11) and a drive unit (13), wherein the assembly (9) is at least partially arranged within the housing (5) and is movably arranged relative to the housing (5), and a rotary knob (60) for selecting the operating mode of the machine tool (1), which is operatively connected to the assembly (9), characterized in that a shaft (61) with a non-circular outer cross-section is arranged non-rotatably on the rotary knob (60), that the shaft (61) together with the rotary knob (60) is slidably arranged on the housing (5), and that a coupling sleeve (70) is arranged on the assembly (9), into which the shaft (61) can be inserted, thereby establishing a non-rotatable connection between the shaft (61) and the coupling sleeve (70).

2. Machine tool according to claim 1, characterized in that a compression spring (69) is provided which acts on one side against the housing (5) and on the other side against the rotary knob (60) with the shaft (61), and which pushes the shaft (61) out of the coupling sleeve (70).

3. Machine tool according to claim 2, characterized in that the compression spring (69) is a spiral spring.

4. Machine tool according to one of the preceding claims, characterized in that the shaft (61) is a polygonal shaft, in particular a square shaft.

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