Hand-Held Machine Tool

Abstract

The disclosure relates to a hand-held machine tool, comprising a drive unit, a gearbox unit, which comprises at least one input shaft and at least one output shaft operatively connected to the input shaft, and a tool holder, which is configured to be driven via the output shaft of the gearbox unit in an oscillating manner about an axis of rotational symmetry of the output shaft. A vibration compensating unit is proposed, which comprises at least one compensating mass which, in order to compensate for a vibration, is driven in at least one operating state against a direction of movement of the tool holder.

Description

PRIOR ART

The invention is based on a hand power tool according to the preamble of claim 1.

There are already known hand power tools comprising a drive unit, a transmission unit, which has at least one input shaft and at least one output shaft that is operatively connected to the input shaft, and comprising a tool receiver, which can be driven in an oscillating manner, via the output shaft of the transmission unit, about a rotational symmetry axis of the output shaft.

DISCLOSURE OF THE INVENTION

The invention is based on a hand power tool comprising a drive unit, a transmission unit, which has at least one input shaft and at least one output shaft that is operatively connected to the input shaft, and comprising a tool receiver, which can be driven in an oscillating manner, via the output shaft, about a rotational symmetry axis of the output shaft.

It is proposed that the hand power tool has a vibration compensating unit, which has at least one compensating mass that, for the purpose of compensating a vibration, in at least one operating state, is driven contrary to a direction of motion of the tool receiver. A “compensating mass” is to be understood to mean a component provided to compensate vibrations, at least partially, preferably fully, in an operating state. “Vibrations” are to be understood to mean, in particular, unwanted motions of the hand power tool that are caused, in particular, by moments of inertia produced by an oscillating motion. The compensating mass according to the invention enables vibrations to be reduced, preferably reduced to zero, when the hand power tool is in an operating state. As a result, advantageously, comfort in operation of the hand power tool can be increased for a user. In addition, noises resulting from unwanted vibrations when the hand power tool is in an operating state can be advantageously reduced, such that, particularly advantageously, the operating comfort can be increased for the user. In addition, the reduction of the vibrations, in particular the reduction of the vibrations to zero, makes it possible to achieve an advantageously precise working result when the hand power tool is in an operating state.

Further, it is proposed that the transmission unit has at least one first cam mechanism, which is provided to drive the tool receiver, and has at least one second cam mechanism, which is provided to drive the compensating mass. A “cam mechanism” is to be understood to mean, in particular, a mechanism by which a shape of a moving curve is picked up by a feeler and transmitted to a further transmission element such as, for example, to the output shaft. Particularly preferably, the cam mechanism has at least one eccentric element. In this context, an “eccentric element” is to be understood to mean a component, in particular a disk-shaped component, whose center point, and preferably also whose center of gravity are disposed so as to be spaced apart from a rotation axis of the component. A “disk-shaped component” is to be understood to mean, in particular, a component whose material extent in the radial direction is at least 10% of a diameter of the component, an axial extent of the component preferably being less than 10% of the diameter.

Owing to the first and the second cam mechanism, a rotary motion of the drive unit can be easily converted into an oscillating motion. In addition, advantageously, the transmission unit according to the invention can be designed in an inexpensive and particularly robust manner.

If the first cam mechanism and the second cam mechanism are operatively coupled to the drive unit, the drive unit can drive the first and the second cam mechanism. Consequently, only one drive unit is required to generate two motions, in particular two mutually opposing motions, of two components that differ from each other. Advantageously, it is thereby possible to save structural space, with the result that the hand power tool can be designed, particularly advantageously, to be small and easy to manipulate.

In addition, it is proposed that a first eccentric element of the first cam mechanism and a second eccentric element of the second cam mechanism are disposed on the input shaft. Since the first eccentric element of the first cam mechanism and the second eccentric element of the second cam mechanism are disposed on the input shaft, an advantageously compact structural design can be achieved. Also conceivable, however, as alternatives or in addition to the cam mechanisms constituted by eccentric elements, are other cam mechanisms, considered appropriate by persons skilled in the art, for converting a rotary motion into an oscillating swivel motion.

In a further design of the invention, it is proposed that the eccentric elements are offset in relation to each other by at least substantially 180°. In this context, “at least substantially 180°” is to be understood to mean that a first straight line through the center point of the first eccentric element and through the rotation axis of the input shaft, which straight line runs perpendicularly in relation to a rotation axis of the input shaft, and a second straight line through the center point of the second eccentric element and through the rotation axis of the input shaft, which straight line runs perpendicularly in relation to the rotation axis of the input shaft, enclose an angle that, in particular, is less than 20°, preferably less than 10°, particularly preferably less than 5°, the center points of the first and the second eccentric elements being disposed, in a radial direction of the input shaft, on mutually at least substantially opposite sides of the input shaft. In a particularly advantageous design, the first and the second straight line are disposed parallelwise in relation to each other, the center points of the first and the second eccentric element being disposed, in the radial direction of the input shaft, on mutually opposite sides of the input shaft. The disposition, according to the invention, of the first and the second eccentric element enables an imbalance of the first and the second eccentric element to be compensated in an advantageously simple manner.

It is proposed that the hand power tool has an angled motion converter, via which the compensating mass of the vibration compensating unit is operatively connected to the second cam mechanism. In this context, a “motion converter” is to be understood to mean a component provided to convert a rotary motion of the drive unit into an oscillating motion of the compensating mass about the rotational symmetry axis of the output shaft. “Angled” is to be understood to mean, in particular, a change in the direction of extent of between 45° and 135°, preferably of between 70° and 110°, and particularly preferably of 90°. The design, according to the invention, of the angled motion converter enables the motion converter to be realized, advantageously, in a space-saving manner and, consequently, an advantageously compact structural design of the transmission unit can be achieved.

It is proposed that the compensating mass of the vibration compensating unit and the angled motion converter are realized in an at least partially integral manner. “Integral” is to be understood to mean, in particular, connected by material bonding such as, for example, by a welding process and/or adhesive bonding process, etc. and, particularly advantageously, formed-on, such as being produced from a casting and/or being produced by a single-component or multi-component injection molding method. Preferably, owing to the integral design of the motion converter and of the compensating unit, savings in components can be made, and as a result, advantageously, an assembly process can be simplified.

It is further proposed that the compensating mass of the vibration compensating unit is rotatably mounted on the output shaft. This makes it possible to achieve a reduction in vibrations in an advantageously effective and, at the same time, simple manner, in particular the reduction of vibrations to zero, when the hand power tool is in an operating state, thereby advantageously enabling the operating comfort for the user to be increased.

DRAWING

Further advantages are given by the following description of the drawing. The drawing shows an exemplary embodiment of the invention. The drawing, the description and the claims contain numerous features in combination. Persons skilled in the art will also expediently consider the features individually and combine them to create appropriate further combinations.

In the drawing:

FIG. 1 shows a perspective side view of a hand power tool according to the invention,

FIG. 2 shows a schematic sectional representation of a partial region of the hand power tool with a transmission unit according to the invention and with a portion of a drive unit,

FIG. 3 shows a schematic sectional representation of the transmission unit of the hand power tool according to the invention, along the line III-III, and

FIG. 4 shows a schematic sectional representation of the transmission unit of the hand power tool according to the invention, along the line IV-IV.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

FIG. 1 shows a hand power tool, which can be driven in an oscillating manner and which has a switch 38, for switching the hand power tool on and off, integrated into a housing 36 of the hand power tool that serves as a handle. Disposed in a front region of the hand power tool is a tool receiver 18, with an insert tool 40 held therein. In addition, the hand power tool comprises a drive unit 10, constituted by an electric motor, not represented in greater detail, and a transmission unit 12. In a region that faces away from the tool receiver 18 in a direction of main extent 42 of the hand power tool, the hand power tool has an electric power cable 44 for supplying electric power to the drive unit 10.

The transmission unit 12 of the hand power tool is represented in greater detail in FIG. 2. The transmission unit 12 has an input shaft 14, which can be driven in rotation by means of the drive unit 10 and which is operatively connected to a first and a second cam mechanism 30, 32. The first cam mechanism 30 has a first eccentric element 31, which is pressed on to a free end of the input shaft 14. The second cam mechanism 32 has a second eccentric element 33, which likewise is pressed on to the input shaft 14. The eccentric elements 31, 33 are identical in their structural design and are disposed with an offset of 180°, such that a center of gravity S₁ of the first eccentric element 31, corresponding to a center point of the first eccentric element 31, and a center of gravity S₂ of the second eccentric element 33, corresponding to a center point of the second eccentric element 33, are disposed in series in a radial direction 46 of the input shaft 14. The first eccentric element 31 is operatively connected to an output shaft 16 of the transmission unit 12 via a first motion converter 48 configured in a level manner. “Configured in a level manner” is to be understood to mean, in particular, that the first motion converter 48 extends, at least substantially, in a plane disposed parallelwise in relation to the input shaft 14 of the drive unit 10 and perpendicularly in relation to the output shaft 16 of the transmission unit 12. “At least substantially” in this case is to be understood to mean, in particular, that the first motion converter 48, with the plane, encloses an angle that, in particular, is less than 15°, particularly preferably is less than 5°. In this exemplary embodiment, the first motion converter 48 is parallel to the plane.

The first motion converter 48 has a first region 50 that faces toward the insert tool 40 in the direction of main extent 42 of the hand power tool and that has a circular recess 52, into which the output shaft 16 is pressed. Furthermore, the first motion converter 48 has a second region 54, which extends, from an end of the first region 50 that faces away from the insert tool 40, in the direction of main extent 42, to the drive unit 10. The second region 54 of the first motion converter 48 has two arms 56. Ends of the arms 56 of the second region 54 of the first motion converter 48 that face toward the drive unit 10 engage, on opposing sides of the first eccentric element 31, on a circumferential surface 58.

The output shaft 16 of the transmission unit 12 extends, perpendicularly in relation to the direction of main extent 42 of the hand power tool, as viewed from the first motion converter 48, toward the tool receiver 18. The output shaft 16 is mounted by two bearings 62, 64 so as to be rotatable relative to the housing 36 of the hand power tool. The tool receiver 18 is disposed on an end of the output shaft 16 that faces away from the first motion converter 48. The tool receiver 18 comprises a seating flange 66, which is pressed on to the output shaft 16 and on which the insert tool 40 is seated when in a mounted state. In addition, the tool receiver 18 comprises a fastening screw 68, which, extending through the insert tool 40, is screwed into a threaded bore, not represented in greater detail, in the output shaft 16. When in a mounted state, a screw head 70 of the fastening screw 68 is supported, in respect of the insert tool 40, on a washer 72. When in a mounted state, the insert tool 40 fixes positively relative to the output shaft 16.

A second motion converter 34, which has an angled configuration, engages on the second eccentric element 33. The second motion converter 34 is configured with a 90° angle, and comprises a first region 74 and a second region 76. The first region 74 of the second motion converter 34 is disposed parallelwise in relation to the input shaft 14 and is connected to a vibration compensating unit 20. The second region 76 of the second motion converter 34 adjoins an end of the first region 74 that faces away from the output shaft 16, and extends, parallelwise in relation to the output shaft 16, in an axial direction 60 of the output shaft, toward the input shaft 14. The second region 76 of the second motion converter 34 has two arms 78, the free ends of which, facing toward the input shaft 14, engage on opposing sides of a circumferential surface 80 of the second eccentric element 33.

The vibration compensating unit 20 is constituted by a compensating mass 22 that is realized so as to be integral with the second motion converter 34 and disposed so as to be rotatable about the output shaft 16. A center of gravity S₃ of the compensating mass 22 is disposed on a side of the output shaft 16 that faces toward the drive unit 10, in a radial direction 82 of the output shaft. A center of gravity S₄ of the insert tool 40 is disposed on the side of the output shaft 16 that is opposite the center of gravity S₃ of the compensating mass 22, in the radial direction 82 of the output shaft 16.

When the hand power tool is in an operating state, the input shaft 14, and the eccentric elements 31, 33 disposed on the input shaft 14, are driven in rotation by the drive unit 10. The eccentric motion of the first eccentric element 31 is taken up by the first motion converter 48 in a plane in which a rotational symmetry axis of the input shaft 14 is located, and which is perpendicular to the output shaft 16. The eccentric motion of the second eccentric element 33 is taken up by the second motion converter 34 in a plane that extends parallelwise in relation to the direction of main extent 42 of the hand power tool and that is perpendicular to the output shaft 16. Produced as a result is an oscillating motion 28 of the first and the second motion converter 34, 48 about an axis that corresponds to a rotational symmetry axis 84 of the output shaft 16.

The oscillating motion 28 of the first motion converter 48 is transmitted, via the output shaft 16, to the tool receiver 18 and to the insert tool 40 held therein. The oscillating motion 28 of the second motion converter 34 is transmitted to the compensating mass 22, which is integrally connected to the second motion converter 34 and rotatably mounted on the output shaft 16 of the transmission unit 12.

Owing to the phase displacement of the oscillating motions 28 of the first and the second motion converter 34, 48, or of the tool receiver 18 and the compensating mass 22, vibrations that are caused by moments of inertia produced by an oscillating motion 28 of the insert tool 40 when the hand power tool is in an operating state are compensated by the compensating mass.

FIG. 3 shows a sectional view along the line III-III. The centers of gravity S₁ and S₂ of the eccentric elements 31, 33, when in the position shown, lie on a straight line that is perpendicular to the direction of main extent 42 and parallel to the axial direction 60. The arms 56 of the first motion converter 48 bear against opposing sides of a circumferential surface 58 of the first eccentric element 31 in the radial direction 46 of the input shaft 14. The arms 78 of the second motion converter 34 bear against the circumferential surface 80 of the second eccentric element 33 in the radial direction 46 of the input shaft 14.

FIG. 4 shows a portion of the hand power tool, in a section along the line IV-IV. The first motion converter 48 comprises the first region 50 having the recess 52, and comprises the second region 54 having the two arms 56. The ends of the arms 56 engage on the circumferential surface 58 of the first eccentric element 31, which is represented in section. The ends of the arms 78 of the second motion converter 34 engage on the circumferential surface 80 of the second eccentric element 33, which is likewise represented in section.

When the hand power tool is in an operating state, a rotary motion 26 of the drive unit 10 and of the input shaft 14 driven by the drive unit 10 is transmitted to the first and the second eccentric element 31, 33 that are pressed on to the input shaft 14. The first and the second eccentric element 31, 33 in this case describe an orbit, which is other than a circle, about a rotational symmetry axis 86 of the input shaft 14. The ends of the arms 56, 78 of the first and the second motion converter 34, 48 each respectively take up a component of the non-circular motion of the first and the second eccentric element 31, 33 in a direction that is perpendicular to the direction of main extent 42 of the hand power tool and perpendicular to the axial direction 60 of the output shaft 16. In this context, “non-circular” is to be understood to mean, in particular, being at least substantially different from a circle. This component of the non-circular motion of the eccentric elements 31, 33 causes an opposing oscillating motion 28 of the first and the second motion converter 34, 48 about the rotational symmetry axis 84 of the output shaft 16.

The oscillating motion 28 of the first motion converter 48 is transmitted to the output shaft 16 pressed into the recess 52, and to the insert tool 40 that is fastened to the output shaft via the tool receiver 18. The oscillating motion 28 of the second motion converter 34 is transmitted to the compensating mass 22 of the vibration compensating unit 20 that is integrally formed on to the second motion converter 34.

Claims

1. A hand power tool comprising:

a drive unit;

a transmission unit including (i) at least one input shaft and (ii) at least one output shaft operatively connected to the input shaft;

a tool receiver configured to be driven in an oscillating manner, via the output shaft of the transmission unit, about a rotational symmetry axis of the output shaft; and

a vibration compensating unit including at least one compensating mass that, in at least one operating state, is configured to be driven contrary to a direction of motion of the tool receiver,

wherein the vibration compensation unit is configured to compensate a vibration.

2. The hand power tool as claimed in claim 1, wherein the transmission unit includes (i) at least one first cam mechanism configured to drive the tool receiver, and (ii) at least one second cam mechanism configured to drive the compensating mass.

3. The hand power tool as claimed in claim 2, wherein the first cam mechanism and the second cam mechanism are operatively coupled to the drive unit.

4. The hand power tool as claimed in claim 3, wherein:

the first cam mechanism includes a first eccentric element disposed on the input shaft, and

the second cam mechanism includes a second eccentric element disposed on the input shaft.

5. The hand power tool as claimed in claim 4, wherein the first eccentric element and the second eccentric element are offset in relation to each other by at least substantially 180°.

6. The hand power tool as claimed in claim 2, further comprising:

an angled motion converter configured to operatively connect the compensating mass of the vibration compensating unit to the second cam mechanism.

7. The hand power tool as claimed in claim 6, wherein the compensating mass of the vibration compensating unit and the angled motion converter are realized in an at least partially integral manner.

8. The hand power tool as claimed in claim 1, wherein the compensating mass of the vibration compensating unit is rotatably mounted on the output shaft.