Machine tool with top positioned decoupling device

Abstract

Machine tool (1), in particular a rotary hammer or chisel hammer, with a housing (5) having a rear grip area (7), with 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), wherein the percussion mechanism (11) has a percussion axis (19) defining a longitudinal direction (Z), and wherein the assembly (9) has a center of mass (15), and with at least one rear Z-decoupling device (35) which is arranged between the assembly (9) and the housing (5), and which springs in when the assembly (9) is moved in the longitudinal direction (Z) towards the grip area (7), wherein the percussion axis (19) and the center of mass (15) define a sagittal plane, wherein the percussion axis (19) and the center of mass (15) lie in the sagittal plane,wherein the impact axis (19) and the sagittal plane define a frontal plane, wherein the frontal plane is orthogonal to the sagittal plane and the impact axis (19) lies in the frontal plane, wherein the frontal plane delimits an upper half-space which does not include the center of mass (15), characterized in that the Z-decoupling device (35) is arranged at least partially in the upper half-space.

Description

[0001] The invention relates to a machine tool, in particular a rotary hammer or chisel hammer, according to the preamble of claim 1. Such a machine tool is equipped with a housing having a rear handle area, with an assembly comprising an impact mechanism and a drive unit, wherein the assembly is at least partially arranged within the housing and is movably arranged relative to the housing, wherein the impact mechanism has an impact axis defining a longitudinal direction, and wherein the assembly has a center of mass, and with at least one rear Z-coupling device, which is arranged between the assembly and the housing and which springs in when the assembly is moved longitudinally towards the handle area, wherein the impact axis and the center of mass define a sagittal plane, and wherein the impact axis and the center of mass lie in the sagittal plane.wherein the axis of impact and the sagittal plane define a frontal plane, wherein the frontal plane is orthogonal to the sagittal plane and the axis of impact lies in the frontal plane, wherein the frontal plane delimits an upper half-space that does not include the center of mass.

[0002] EP4331774 A1 describes a machine tool, in particular a rotary hammer or chisel hammer, with a housing having a grip area and an assembly comprising a percussion mechanism and a drive mechanism, wherein the assembly is substantially arranged inside the housing and is movably arranged relative to the housing.

[0003] The object of the invention is to provide a machine tool that has particularly good vibration decoupling properties with particularly low manufacturing and maintenance costs.

[0004] 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.

[0005] A machine tool according to the invention is characterized in that the Z-decoupling device is arranged at least partially in the upper half-space.

[0006] In connection with the invention, it was recognized that, particularly when the assembly is designed in a so-called angular configuration, the impact axis is frequently spaced away from the assembly's center of mass, with the impact axis running above the center of mass when the machine tool is in an upright position. Consequently, the impact impulses directed backwards in the longitudinal direction Z are split into a translational movement and a rotational movement around the center of mass, specifically a downward-facing rotational movement around the center of mass. This rotational movement is often comparatively difficult to decouple.

[0007] The invention addresses this issue and provides for arranging the Z-axis decoupling device such that, when the machine tool is in an upright position, it lies at least partially, and preferably completely, above the impact axis. The Z-axis decoupling device thus lies partially, and preferably completely, within a half-space located on the side of the assembly's frontal plane facing away from the center of mass. The frontal plane of the assembly is characterized by the fact that it encompasses the impact axis and is orthogonal to a sagittal plane, which in turn encompasses the impact axis and the center of mass.By arranging the Z-coupling device above the impact axis (with the machine tool upright), the Z-coupling device can counteract the downward rotational tendency described above in a particularly simple and effective manner, and can in particular lead to an essentially translational movement of the assembly.

[0008] The Z-decoupling device defines a spring axis that runs parallel to the impact axis. It is particularly preferred that the spring axis is located in the upper half-space. The lower the spring axis is located in the upper half-space, i.e., the greater the distance of the spring axis from the impact axis, the lower the counterforce of the Z-decoupling device needs to be, meaning the simpler its design can be.

[0009] In particular, it may be provided that the Z-decoupling device is arranged entirely in the upper half-space, which can be advantageous with regard to force absorption and design effort.

[0010] It is particularly preferred that the Z-decoupling device comprises at least one elastomeric element. In particular, the elastomeric element can consist of an open-pore, microcellular, and / or water-foamed polyurethane-based elastomeric foam. This allows for a particularly effective Z-decoupling device to be obtained in a particularly simple manner.

[0011] In particular, the assembly can be designed in an angled configuration. As already indicated above, the configuration according to the invention is particularly suitable for angled construction with its comparatively low center of gravity. In an angled configuration, it can be provided that an output axis of the drive unit runs orthogonally to the impact axis and preferably intersects it. In particular, the output axis can lie in the sagittal plane.

[0012] 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 simplified side sectional view with section plane perpendicular to the transverse direction (and parallel to the sagittal plane of the assembly) of a first embodiment of a machine tool in the machine tool's rest position; Fig. 2 a sectional view of the machine tool according to Fig. 1 with cutting plane perpendicular to the vertical direction (and parallel to the frontal plane of the assembly), in the rest position of the machine tool.

[0013] The figures show a first embodiment of a machine tool 1, which in this case is designed as a rotary hammer or combination hammer, but in an alternative embodiment could also be designed, for example, as a chisel hammer or the like. In this case, the machine tool 1 is designed as a cordless machine tool with a battery 3, but in an alternative embodiment it could also be designed for mains operation.

[0014] The machine tool 1 has a housing 5 which has a rear grip area 7 in a D-shape. The housing 5, which can be made of one or more parts, is fixedly connected to the grip area 7 accessible to the user. In this case, the housing 5 is divided longitudinally Z and constructed in a so-called cup design. Alternatively, the housing 5 can also have two housing halves that can be joined together in the transverse direction X and be constructed in a so-called shell design.

[0015] Within the housing 5, an assembly 9 is arranged, comprising a conventionally designed striking mechanism 11 and a drive unit 13 designed as an electric motor for driving the striking mechanism 11. The assembly 9 is designed in an L-shape, with the striking mechanism 11 forming a first leg of the L and the drive unit 13 forming a second leg. In particular, the drive unit 13 has an output shaft extending along an output axis 99, which drives the striking mechanism 11. Due to the L-shape, the output axis 99 is perpendicular to the striking axis 19.

[0016] The machine tool 1 has a tool holder 16 in a conventionally known manner, via which a tool 17, for example a chisel or the like, can be detachably connected to the assembly 9, in particular its impact mechanism 11.

[0017] The assembly 9 enables chisel operation, whereby in chisel operation the tool 17 is moved back and forth in an oscillating motion in the direction of the impact axis 19. In hammer drilling operation, the tool 17 additionally performs a rotating motion around the impact axis 19.

[0018] The figures 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. Without the application of an external force, the longitudinal direction Z coincides with the impact axis 19, which is defined by a central axis of the tool 17 held in the tool holder 16 or of the tool holder 16 itself. Without the application of an external force, the vertical direction Y is parallel to the output axis 99 of the drive unit 13.

[0019] The assembly 9 can have a separate inner housing 21, in particular made of plastic, 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.

[0020] The machine tool 1 also has a side handle 27, which forms a front gripping area. The side handle 27 is connected to the housing 5 in a side handle mounting area located near the tool holder 16. In the figures, the side handle 27 extends essentially in the transverse direction X. However, it can be arranged on the housing 5 in a way that is continuously adjustable in the circumferential direction relative to the longitudinal direction Z.

[0021] The assembly 9 is movably mounted in the housing 5, particularly at least in the longitudinal direction Z. The assembly 9 is shown in the figures in its rest position, in which the machine tool 1 is not in operation, or in which the assembly 9 is arranged in a forward end position relative to the housing 5 in the longitudinal direction Z. During operation of the machine tool, vibrations arise from the interaction between the workpiece and the tool 17, which act mainly in the direction of the impact axis 19, i.e., in the longitudinal direction Z. These vibrations can be transmitted to the housing 5 via a rear Z-decoupling device 35. The rear Z-decoupling device 35 is arranged between the assembly 9 and the housing 5 and compresses when the assembly 9 is moved in the longitudinal direction Z towards the grip area 7. The purpose of the rear decoupling device 35 is to dampen the vibrations that arise in the area of ​​the assembly 9 during operation of the machine tool 1.To reduce or dampen accelerations as much as possible. In addition to the rear Z-decoupling device 35, further Z-decoupling devices can be provided in parallel to the Z-decoupling device 35, as well as further decoupling devices between the housing 5 and the assembly 9.

[0022] Due to the angular design of the machine tool 1, the center of mass 15 of the assembly 9 is not located on the impact axis 19, but rather below the impact axis 19 when the machine tool 1 is in an upright position. Consequently, impacts directed backwards in the direction of the impact axis 19 cause the assembly 9 to tend to rotate around the transverse axis X.

[0023] This tendency to rotate is counteracted by the positioning of the Z-decoupling device 35. The Z-decoupling device 35 is located in the side view of the Figure 1above the impact axis 19. In three-dimensional space, the Z-decoupling device 35 is located at least partially, but in the present embodiment completely, in a half-space that is delimited from the frontal plane, which in Figure 1 perpendicular to the drawing plane and in Figure 2 The frontal plane of assembly 9 runs parallel to the drawing plane and contains the impact axis 19, with the center of mass 15 lying outside the said half-space. The frontal plane of assembly 9 runs orthogonally to the sagittal plane of assembly 9, which contains both the impact axis 19 and the center of mass 15, with the sagittal plane in Figure 1 parallel to the drawing plane and in Figure 2 runs perpendicular to the drawing plane.

[0024] The Z-decoupling device 35 exhibits spring properties and / or damping properties at least in the longitudinal direction Z (it can also act in the X and Y directions) and is designed here with a spring axis 91 that runs parallel to the impact axis 19 in the upper half-space. In the present embodiment, the spring axis 91 lies in the sagittal plane.

[0025] In the present embodiment, the Z-decoupling device 35 is shown by way of example as a coil spring. Alternatively or additionally, it can also have at least one elastomeric element, preferably a polyurethane-based elastomeric element.

Claims

1. Machine tool (1) with a housing (5) having a rear grip area (7), with an assembly (9) comprising a percussion device (11) and a drive device (13), wherein the assembly (9) is at least partially arranged within the housing (5) and is movably arranged relative to the housing (5), wherein the percussion device (11) has a percussion axis (19) defining a longitudinal direction (Z), and wherein the assembly (9) has a center of mass (15), and with at least one rear Z-decoupling device (35) which is arranged between the assembly (9) and the housing (5) and which springs when the assembly (9) is moved in the longitudinal direction (Z) towards the grip area (7), wherein the percussion axis (19) and the center of mass (15) define a sagittal plane, wherein the percussion axis (19) and the center of mass (15) lie in the sagittal plane,wherein the impact axis (19) and the sagittal plane define a frontal plane, wherein the frontal plane is orthogonal to the sagittal plane and the impact axis (19) lies in the frontal plane, wherein the frontal plane delimits an upper half-space which does not include the center of mass (15), , characterized by that the Z-decoupling device (35) is arranged at least partially in the upper half-space.

2. Machine tool according to claim 1, characterized by that the Z-decoupling device (35) defines a spring axis (91) which runs parallel to the impact axis (19), wherein the spring axis (91) is arranged in the upper half-space.

3. Machine tool according to one of the preceding claims, characterized by that the Z-decoupling device (35) is arranged completely in the upper half-space.

4. Machine tool according to one of the preceding claims, characterized by thatthe Z-decoupling device (35) has at least one elastomer element.

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