Electric hand tool with accumulator unit removably secured to machine housing

Abstract

The present invention relates to an electric hand tool, in particular an impact hammer, comprising a tool receiving unit (1) for a tool arranged along an impact axis (X), a drive unit for the tool which is subsequently accommodated in a machine housing (2), and a handle (3) arranged on the machine housing (2) opposite the tool receiving unit (1), and at least one accumulator unit (8a, 8b) are removably fixed to the machine housing (2) for the power supply, and at least one housing recess (7a, 7b) extending transversely to the impact axis (X) is provided in the area of ​​the machine housing (2) for interchangeably accommodating the accumulator units (8a, 8b), The electric hand tool has accumulator units (8a, 8b) arranged so that the center of gravity of the entire accumulator units relative to the radial direction of the impact axis (X) is within the lateral dimension of the drive unit.

Description

[Technical Field]

[0001] The present invention relates to an electric hand tool, in particular an impact hammer, comprising a tool receiving unit for a tool arranged along an impact axis X, a drive unit for the tool which is subsequently accommodated in a housing, and a handle arranged on the machine housing opposite the tool receiving unit, wherein at least one accumulator unit removably fixed to the machine housing is provided for supplying electrical energy to the drive unit.

[0002] The application field of the present invention extends to cordless, i.e., battery-operated, power hand tools, especially so-called in-line power hand tools. The tool receiving unit, the machine housing, and the handle components, which are typically arranged on the machine housing, are oriented along an impact axis to efficiently apply the necessary manual pressure to the chisel tool and to enable the most accurate possible handling of the power hand tool in question. At least one replaceable accumulator unit for power supply must be arranged on or within the housing so that it is accessible from the outside. However, it is also conceivable to apply the solution according to the present invention to other battery-operated power tools in which the accumulator unit is integrated to optimize installation space. The accumulator unit consists of a housing, usually made of plastic, in which multiple rechargeable battery cells are housed and have electrical contacts electrically connected to each other. The accumulator unit is a relatively sensitive and safety-related component of the power hand tool. In the event of damage, an exothermic reaction may cause damage in individual cases, which must be taken into consideration when positioning the accumulator unit relative to the rest of the power hand tool. [Background technology]

[0003] JP 2016-165784 A discloses a typical power hand tool with an in-line design. Along the tool axis, a tool receiving unit, a machine housing for housing a drive unit in a vibration-damping manner, and a handle molded into the rear of the machine housing are provided. In the interior area of ​​the handle, accumulator units are arranged adjacent to each other on the housing end face adjacent to the drive unit located therein so as not to interfere with the function of the handle. In this way, the accumulator units are accessible for replacement, and this arrangement does not significantly interfere with the in-line design. However, their close proximity to the operator's hand leaves a risk of injury in the event of a defect.

[0004] U.S. Pat. No. 5,208,525(A) shows a power supply arrangement for a cordless machine, in which a battery unit partially forming the shape of the machine housing is removably attached to the machine housing. The removably attached battery unit is located outside the handle, in contrast to the above-mentioned prior art. However, with regard to power hand tools, this prior art document only includes drilling and sawing tools that are not of the inline type. Rather, the handle area protrudes radially from the tool axis, particularly in the case of drilling tools, which provides support for the operator against machine torque but also worsens the vibration characteristics of the power hand tool.

[0005] German Utility Model No. 29513651 (U1) discloses a battery-powered electric hand tool, the handle of which incorporates a recess for completely accommodating a battery unit. The accumulator unit is removably connected to the part of the machine housing forming the handle by means of a catch. A problem with this technical solution is that the installation space in the handle area of ​​the machine housing is limited, and only accumulator units with low energy capacity and correspondingly small dimensions can be accommodated in such an area.

[0006] The object of the present invention is to further improve cordless power hand tools of the general type, in particular cordless power hand tools designed with an in-line structure, so that, on the one hand, one or more removably fixable accumulator units with a higher energy capacity are arranged in an easily replaceable manner, and, on the other hand, tool handling is improved.

[0007] Summary of the Invention The object of the invention is achieved by means of an electric hand tool in accordance with the general terms of claim 1 together with the features characterizing it. The following dependent claims describe advantageous developments of the invention.

[0008] The present invention includes the technical teaching that the machine housing of an in-line design power hand tool has at least one housing recess extending transversely to the impact axis X for replaceably accommodating at least one accumulator unit, and the accumulator unit is positioned so that its overall center of gravity relative to the impact axis X is within the lateral dimension of the drive unit.

[0009] In other words, the at least one accumulator unit is positioned in the region of the impact axis X within a range of accuracy that allows the overall center of gravity in the radial direction to be no further from the impact axis X than the geometric dimensions of the drive unit in the radial direction, in particular the diameter of the impact mechanism, when the electric hand tool is designed as an impact hammer.

[0010] Advantageously, in this way the weight of the at least one accumulator unit does not significantly change the overall center of gravity, which improves the vibration behavior in all directions and therefore the handling of a power hand tool designed according to the invention, in particular with regard to simple manual chisel guidance and rotation of the power hand tool along the impact axis X with minimal effort on the part of the user.

[0011] At least one housing recess for accommodating one or more accumulator units is preferably located between the drive unit and the handle in the machine housing relative to the impact axis X. This is because extending the housing allows for sufficient installation space at this location, even for relatively large accumulator units or multiple accumulator units. Locating the housing recess between the drive unit and the handle also allows for the accumulator units to be accommodated in a manner that protects them from critical loads. The internal location of the electrical connection contacts also protects them from damage and dirt. Furthermore, this arrangement of the housing recess in the context of adjacent structural units allows for the minimization of internal machine cable length, which allows for higher currents with smaller cross-sections. This also improves the electromagnetic compatibility of the power hand tool.

[0012] According to a first preferred embodiment, the housing recess is accessible from the underside and / or the top side of the machine housing so that the assigned accumulator unit can be inserted into the housing recess from below or from above. According to the invention, the housing of the accumulator unit is dimensioned in relation to the geometric dimensions of the housing recess so as to fully accommodate the accumulator unit in order to achieve the above-mentioned technical advantages.

[0013] According to a second preferred embodiment, this can also be implemented by arranging a housing recess on one of the sides of the machine housing so that the accumulator unit can be inserted laterally into the machine housing. In particular, a left-side arrangement on the machine housing allows a right-handed user, who grips the handle of the machine housing with his right hand, to load or remove the accumulator unit with his left hand.

[0014] The housing recess according to the invention can optionally extend continuously through the machine housing, i.e., continuously from top to bottom as for the preferred embodiment described above, or laterally to the side relative to the machine housing. The accumulator unit can be mounted or removed from both sides via opposing recess openings, thereby eliminating the right-handed restriction given as an example above.

[0015] However, it is also conceivable to insert the accumulator units through each recess opening within the framework of a continuous housing recess, in which case the accumulator units can also extend radially beyond the machine housing, since such an arrangement has a compensating effect with regard to the overall center of gravity.

[0016] Preferably, the at least one accumulator unit is arranged relative to the machine housing so that it can be completely placed in a housing recess that is symmetrically positioned with respect to two machine planes A and B that are arranged at right angles to each other and coincide with the line of intersection with the impact axis X of the electric hand tool. Machine plane A forms a plane that is vertical to the electric hand tool, and machine plane B, which is arranged laterally thereto, forms a plane that is horizontal to the electric hand tool when the electric hand tool is in a horizontal holding position.

[0017] Further means for improving the invention will be explained in more detail below in conjunction with the description of preferred exemplary embodiments of the invention with reference to the drawings. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of a power hand tool having various options for the placement of the accumulator unit; [Figure 2] FIG. 1 is a perspective view of the same power hand tool showing the locations of machine planes A and B. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1, a battery-operated electric hand tool designed as an impact hammer essentially consists of a tool-receiving unit 1 arranged along an impact axis X for removably mounting a tool chisel (not further shown), and an axially continuing housing 2 for accommodating an internal drive unit (not visible here) for the tool. In the case of an impact hammer, the drive unit comprises the well-known combination of an electric motor with a gearbox and an impact mechanism.

[0020] Axially opposite to the tool receiving unit 1, a handle 3 is arranged on the machine housing 2, which handle 3 is designed to be molded directly onto the machine housing 2.

[0021] In this exemplary embodiment, the machine housing 2 is made up of three parts: a front housing part 4, a middle housing part 5 and a rear housing part 6. The front housing part 4 is assigned to the tool receiving unit 1 and the rear housing part 6 is assigned to the handle 3.

[0022] The central housing part 5 of the machine housing 2 has a vertical housing recess 7a extending transversely to the impact axis X for interchangeably accommodating an accumulator unit 8a. The assigned accumulator unit 8a can be arranged in the housing recess 7a in such a way that its overall center of gravity relative to the impact axis X lies within the lateral dimension of the drive unit. This means that the overall center of gravity of the electric hand tool relative to the impact axis X does not change outside the lateral dimension of the drive unit it is in when the accumulator unit is fitted.

[0023] In combination with this preferred exemplary embodiment, an alternative variant is also shown in which the housing recesses extend from the side of the machine housing at right angles to the above-mentioned vertical housing recess 7a. In such a horizontally extending housing recess 7b, an accumulator unit 8b can be accommodated and can be mounted and removed from the side. In contrast, the housing recess 7a is arranged on the lower and / or upper side of the machine housing 2.

[0024] Both the vertical housing recess 7a and the horizontal housing recess 7b may extend continuously through the machine housing such that opposing recess openings are formed.

[0025] The housing recess 7a or 7b arranged in the region of the central housing part 5 of the machine housing 2 is located relative to the impact axis X between the drive unit on the one hand, which is adjacent to the tool receiving unit 1 on the inside, and the handle 3 on the other hand.

[0026] The accumulator units 8a, 8b in each case have a plastic housing 9 made of plastic material on which electrical contacts 10 are located, which are connected to the interior of a rechargeable battery cell (not visible here) contained within the plastic housing 9.

[0027] The accumulator unit 8a or 8b can be fully secured in the assigned housing recess 7a or 7b by means of a clip mechanism that can be removed with one hand.

[0028] 2 shows the position of the vertical machine plane A and the horizontal machine plane B relative to the impact axis X. The intersection between the two machine planes A and B lies on the impact axis X. In this regard, the continuous housing recess 7a in the central housing part 5 is positioned symmetrically with respect to both the machine plane A and the machine plane B. The accumulator unit 8a removably fixed thereto is also arranged symmetrically with respect to the assigned housing recess 7a and both machine planes A and B, such that its overall center of gravity in the radial direction of the impact axis X lies within the lateral dimension of the internal drive unit according to the invention.

[0029] The invention is not limited to the exemplary embodiments described above, but rather contemplates modifications that fall within the scope of protection of the following claims. For example, it is also possible to accommodate more than one accumulator unit in the housing recess, as long as the position of the overall center of gravity relative to the impact axis X does not exceed the definition according to the invention. [Explanation of symbols]

[0030] 1 Tool Receiving Unit 2 Machine housing 3 Handle 4 Front housing part 5 Central housing part 6 Rear housing part 7 Housing recess 8 Accumulator Unit 9 Plastic Housing 10 Electrical contacts X impact axis A Vertical machine plane B horizontal mechanical plane

Claims

1. An electric hand tool, in particular an impact hammer, comprising a tool receiving unit (1) for a tool arranged along an impact axis (X), a drive unit for said tool which is subsequently accommodated in a machine housing (2), and a handle (3) arranged on the opposite side of said tool receiving unit (1) in said machine housing (2), wherein at least one accumulator unit (8a, 8b) is removably fixed to said machine housing (2) for the purpose of supplying power thereto; 1. The electric hand tool of claim 1, wherein at least one housing recess (7a, 7b) extending transversely to the impact axis (X) is provided in the area of ​​the machine housing (2) for interchangeably accommodating the accumulator units (8a, 8b), the accumulator units (8a, 8b) being arranged such that their overall center of gravity in the radial direction of the impact axis (X) is within a lateral dimension of the drive unit.

2. the housing recess (7a) is arranged on the lower and / or upper side of the machine housing (2), The power hand tool of claim 1 .

3. characterised in that the housing recess (7b) is arranged on one of the sides of the machine housing (2), The power hand tool of claim 1 .

4. the housing recesses (7a, 7b) extend continuously through the machine housing (2) so as to form two recess openings facing each other, 4. The electric hand tool according to claim 1.

5. the housing recesses (7a, 7b) are arranged inside the machine housing (2) with respect to the impact axis (X) between the drive unit and the handle (3) located therein; 5. The electric hand tool according to claim 1.

6. characterised in that the impact axis (X) extends on the intersection of two machine planes (A, B) arranged at right angles to one another, and the accumulator units (8a, 8b) are positioned symmetrically with respect to both machine planes (A, B).

6. The electric hand tool according to claim 1.

7. the accumulator units (8a, 8b) are fully secured in the housing recesses (7a, 7b) using a clip mechanism that can be removed with one hand.

7. The electric hand tool according to claim 1.

8. characterised in that the drive unit housed in the machine housing (2) comprises an electric motor with a downstream impact mechanism, 8. The electric hand tool according to any one of claims 1 to 7.

9. characterised in that the handle (3) is designed to be moulded directly onto the machine housing (2), 9. The electric hand tool according to any one of claims 1 to 8.

10. the accumulator unit (8a, 8b) comprises a plastic housing (9) containing at least one rechargeable battery cell; 10. The electric hand tool according to any one of claims 1 to 9.

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