Hand operated power tool

Abstract

A hand operated power tool comprising a housing with a motor and a working element performing an actuating movement if the tool is actuated. The motor is adapted to actuate a tool shaft in order to make it perform a rotational movement. A carrier element is functionally located between the tool shaft actuated by the motor and the working element for translating the rotational movement of the tool shaft into the actuating movement of the working element. In order to provide for a power tool, which allows perfect working of a workpiece with different types of actuating movements and/or working elements, it is suggested that the working element and the carrier element make part of a functional unit constituting a unit separate of the rest of the tool, wherein the functional unit is detachably fixed to the rest of the tool, in particular to the tool shaft.

Claims

1. A hand operated power tool comprising a housing with a motor operatively supported in the housing and a tool shaft operatively connected to said motor and driven by said motor so as to perform a rotational movement, at least one functional unit mountable to the tool shaft, said functional unit including a carrier and a working element wherein said carrier is disposed between said tool shaft of said working element such that rotational movement of the tool shaft is translated into the actuating movement of the working element through said carrier, wherein the functional unit is separate from the rest of the tool but is fixed to the rest of the tool by a releasable connection, which is torque proof at least in one direction of rotation of the working element, and is detachably fixed to the tool shaft, said housing has a longitudinal extension enclosing the motor, a first gear mechanism and a first tool shaft are located in the housing and extend along a longitudinal extension of the housing, wherein the first tool shaft rotates about a first rotational axis, and wherein a second tool shaft, which actuates the functional unit, rotates about a second rotational axis, wherein the two axes intersect each other in an angle being larger than 0° and smaller than 180°.

2. The hand operated power tool as set forth in claim 1, wherein the carrier element of the functional unit is detachably fixed to the tool shaft by a threaded connection designed such that acceleration of the tool shaft upon activation of the tool fastens the threaded connection and tightens the fixation of the functional unit to the rest of the tool.

3. A hand operated power tool comprising a housing with a motor operatively supported in the housing and a tool shaft operatively connected to said motor and driven by said motor so as to perform a rotational movement, at least one functional unit mountable to the tool shaft, said functional unit including a carrier and a working element wherein the working element comprises a backing plate and a working sheet on a bottom surface of the backing plate, the working sheet adapted for working a surface of a workpiece, wherein the backing plate is releasably fixed to the rest of the functional unit, wherein said carrier is disposed between said tool shaft of said working element such that rotational movement of the tool shaft is translated into the actuating movement of the working element through said carrier, wherein the functional unit is separate from the rest of the tool, and is detachably fixed to the tool shaft, said housing has a longitudinal extension enclosing the motor, a first gear mechanism and a first tool shaft are located in the housing and extend along a longitudinal extension of the housing, wherein the first tool shaft rotates about a first rotational axis, and wherein a second tool shaft, which actuates the functional unit, rotates about a second rotational axis, wherein the two axes intersect each other in an angle being larger than 0° and smaller than 180°.

4. The hand operated power tool as set forth in claim 3, wherein the backing plate is releasably fixed to said carrier element of the functional unit by a further threaded connection.

5. The hand operated power tool as set forth in claim 1, wherein the tool is one of a polisher, a sander, or a grinder.

6. The hand operated power tool as set forth in claim 1, wherein the angle between the two axes is approximately 90°.

7. The hand operated power tool as set forth in claim 1, wherein the power tool comprises a second gear mechanism adapted for translating the rotational movement of the first tool shaft into a rotational movement of the second tool shaft.

8. A hand operated power tool comprising a housing with a motor operatively supported in the housing and a tool shaft operatively connected to said motor and driven by said motor so as to perform a rotational movement, at least one functional unit mountable to the tool shaft, said functional unit including a carrier and a working element wherein said carrier is disposed between said tool shaft of said working element such that rotational movement of the tool shaft is translated into the actuating movement of the working element through said carrier, wherein the functional unit is separate from the rest of the tool, and is detachably fixed to the tool shaft, wherein the rest of the tool includes a receiving section to which the functional unit is detachably fixed, wherein said receiving section makes part of the tool shaft and is designed to receive different types of functional units comprising different types of carrier elements and/or working elements, said housing has a longitudinal extension enclosing the motor, a first gear mechanism and a first tool shaft are located in the housing and extend along a longitudinal extension of the housing, wherein the first tool shaft rotates about a first rotational axis, and wherein a second tool shaft, which actuates the functional unit, rotates about a second rotational axis, wherein the two axes intersect each other in an angle being larger than 0° and smaller than 180°.

9. The hand operated power tool as set forth in claim 8, wherein a plurality of different functional units are available, each of which can be detachably fixed to the rest of the tool and each of which has a carrier element designed such that the working element of the functional unit performs a certain type of actuating movement, the actuating movements of the working elements of the different functional units differing from one another by type and/or degree.

10. The hand operated power tool as set forth in claim 9, wherein the differing types of actuating movements performed by the working elements of the different functional units comprise one or more of the following kind: a rotational, a random-orbital, a roto-orbital, a planetary, a linear, a linear or rotary alternating back and forth actuating movement.

11. The hand operated power tool as set forth in claim 8, wherein a plurality of different functional units are available, each of which can be detachably fixed to the rest of the tool and each of which has a working element, the working elements of the different functional units differing from one another by type and/or dimension.

12. The hand operated power tool as set forth in claim 11, wherein the differing types of working elements of the different functional units comprise one or more of the following kinds of working elements: having a backing plate with a working sheet integrally formed on a bottom surface of the backing plate, having a backing plate with an attachment layer on its bottom surface for releasably attaching separate working sheets, the working sheets being adapted for polishing, sanding, abrading or grinding surfaces of workpieces and/or having backing plates with different forms, like a delta shape, a rectangular shape or a circular shape, and/or having backing plates with different dimensions.

13. The hand operated power tool as set forth in claim 8, wherein the power tool is provided with means for inhibiting the rotation of the tool shaft.

14. The hand operated power tool as set forth in claim 13, wherein the means for inhibiting the rotation of the tool shaft comprise a brake or interference button located in a front part of the power tool, in particular at the top of a tool head.

15. The hand operated power tool as set forth in claim 3, wherein the working sheet is an integral part of the backing plate or is part of a separate working sheet releasably fixed to the bottom surface of the backing plate.

16. A hand operated power tool comprising a housing with a motor operatively supported in the housing and a tool shaft operatively connected to said motor and driven by said motor so as to perform a rotational movement, at least one functional unit mountable to the tool shaft, said functional unit including a carrier and a working element wherein said carrier is disposed between said tool shaft of said working element such that rotational movement of the tool shaft is translated into the actuating movement of the working element through said carrier, wherein the functional unit is separate from the rest of the tool, and is detachably fixed to the tool shaft, said housing has a longitudinal extension enclosing the motor, a first gear mechanism and a first tool shaft are located in the housing and extend along a longitudinal extension of the housing, wherein the first tool shaft rotates about a first rotational axis, and wherein a second tool shaft, which actuates the functional unit, rotates about a second rotational axis, wherein the two axes intersect each other in an angle that is approximately 98°.

17. A hand operated power tool comprising a housing with a motor operatively supported in the housing and a tool shaft operatively connected to said motor and driven by said motor so as to perform a rotational movement, at least two interchangeable functional units, each interchangeably mountable to the tool shaft, each of said functional units including a working element and a carrier element, wherein one of said interchangeable functional units is adapted to be rotatably driven in response to the rotational movement of said tool shaft and said other of said interchangeable functional units is adapted to be driven in an eccentric movement in response to rotational movement of said tool shaft, wherein each carrier is disposed between said tool shaft of said associated working element such that rotational movement of the tool shaft is translated into the actuating movement of the working element through said carrier, wherein the functional unit is separate from the rest of the tool, and is detachably fixed to the tool shaft, said housing has a longitudinal extension enclosing the motor, a first gear mechanism and a first tool shaft are located in the housing and extend along a longitudinal extension of the housing, wherein the first tool shaft rotates about a first rotational axis, and wherein a second tool shaft, which actuates the functional unit, rotates about a second rotational axis, wherein the two axes intersect each other in an angle being larger than 0° and smaller than 180°.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantages of the invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

(2) FIG. 1 is a side view of a hand held and/or hand guided power tool according to the present invention;

(3) FIG. 2 is a top view of the power tool of FIG. 1;

(4) FIG. 3 is a longitudinal sectional view of the power tool of FIGS. 1 and 2 along line III-III of FIG. 2;

(5) FIG. 4 is a sectional view of detail IV of FIG. 3;

(6) FIG. 5 is the detail IV shown in FIG. 4 with a first embodiment of a functional unit according to the present invention detached from the rest of the power tool; and

(7) FIG. 6 is the detail IV shown in FIG. 4 with a second embodiment of a functional unit according to the present invention detached from the rest of the power tool.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIGS. 1 and 2 show a side view of a hand held and/or hand guided power tool embodied as a polishing machine or a polisher. The polisher in its entirety is designated with reference sign 1. Alternatively, the power tool 1 according to the present invention could also be embodied as a sander or a grinder, or even as a drill, a cordless screw driver, a mixer, or an electric saw, only to mention a few examples.

(9) The polisher 1 includes a housing 2 made up of essentially two main parts, a rear part 2a and a front part 2c. In more detail the housing 2 comprises the rear part 2a, a distal end part 2b, the front part 2c and a front casing 2e. The rear part 2a is preferably made of a rigid plastics material. Of course, the rear part 2a of the housing could also be made of a different rigid material, for example metal or carbon fiber. Further, the rear part 2a of the housing 2 could comprise regions provided with resilient material like a soft plastic material or rubber in order to ensure safe and comfortable gripping, holding and guiding of the power tool 1 by a user or operator. The rear part 2a of the housing is preferably divided into two half shells which are attached on one another along an essentially vertical plane and held together by screws 3.

(10) The rear part 2a of the housing 2 includes an actuation lever 4 co-operating with a switch for turning on and off the polisher 1. The actuation lever 4 has a blocking mechanism 5 for avoiding unintentional activation of the tool 1. Furthermore, the rear part 2a of the housing is provided with a turn wheel 6 for speed regulation of a tool's motor. A distal rear end 2b of the rear part 2a of the housing can be removed in order to withdraw a battery 14 (see FIG. 3) from the inside of the rear part 2a of the housing 2. The battery 14 provides the polisher 1 and its electronic components, respectively, with electric energy necessary for their operation. Of course, the polisher 1 could also be operated with electric energy from a mains power supply. In that case a battery 14 would not be necessary and the compartment for the battery could be used for accommodating a transformer and other electric circuitry for transforming the mains voltage from 100V to 250V and from 50 Hz to 60 Hz, into an operating voltage (e.g. 12V, 18V, or 24V) for the electronic components of the polisher 1. The distal end 2b of the housing 2 is secured to the rear part 2a by a snap-action connection comprising two opposite lateral knobs 7 for releasing the snap-connection. For removing the distal rear end 2b from the rear part 2a of the housing 2, the lateral snap-releasing knobs 7 are pressed, thereby releasing the snap-action connection and allowing separation of the distal end 2b of the housing 2 from the rear part 2a and withdrawal of the battery 14 from the housing 2. The rear part 2a of the housing 2 is provided with a plurality of slots 8 enabling an airstream from the inside to the outside of the housing 2 and cooling of the electronic components located inside the housing 2.

(11) Furthermore, located inside the rear part 2a of the housing 2 is an electric motor 16, preferably a brushless (BL) motor, in particular a BL direct current (BLDC) motor, with a motor shaft 16a, which actuates a first gear mechanism 17 which can determine a certain ratio between the rotational speed of the motor shaft 16a and the rotational speed of a tool shaft 19 and/or 23, which eventually drives the working element 11. Depending on the design of the gear mechanism 17, the ration can be 1, larger than 1 or smaller than 1. Usually, the ratio will be larger than 1 because the motor shaft 16a turns faster than the tool shaft 23. Preferably, the first gear mechanism 17 is an epicyclic gear. The gearbox output shaft is designated with reference sign 18. The output shaft 18 is connected to a first tool shaft 19 by a coupling assembly 20.

(12) The power tool 1 can include a second gear mechanism 24 in order to translate the rotational movement of the motor shaft 16a and of the first tool shaft 19, respectively, about a first rotational axis 22 into a rotational movement of a second tool shaft 23, which actuates the working element 11, about a second rotational axis 12, whereas the two axes 12, 22 intersect at a certain angle larger than 0° and smaller than 180°, in particular around 90°. Preferably, the angle of the two rotational axes 12, 22 is approximately 98°. The second gear mechanism 24 can include a bevel gear with two bevel gear wheels 26. In contrast to the embodiment of FIG. 3 the first and second gear mechanism 17, 24 could also be designed as a single gear mechanism located in the front part of the tool 1, e.g. in a tool head 9. Alternatively, the tool 1 according to the present invention may also include only one of the two gear mechanisms 17, 24 or no gear mechanism at all. Furthermore, a printed circuit board (PCB) comprising electric and electronic components which together form at least part of a control unit 6a is located inside the housing 2. Preferably, the control unit 6a includes a microcontroller and/or a microprocessor for processing a computer program which is programmed to perform the desired motor control function, when it is processed on the microprocessor.

(13) Attached to a front end of the rear part 2a is the front part 2c of the housing 2. The front part 2c is preferably made of metal or a rigid plastics material. The front part 2c can be fixed to the rear part 2a of the housing 2 by screws or similar attachment mechanism commonly known in the art. Of course, the front part 2c and the rear part 2a of the housing 2 could be embodied as a single common housing unit, too. A tool head 9 is fixed to a front distal end 2d of the front part 2c of the housing 2. The tool head 9 is preferably fixed to the distal end 2d by screws or similar attachment mechanism or by a threaded connection 2f. The tool head 9 comprises the casing 2e preferably made of metal or a rigid plastics material. The tool head 9 further includes a working element 11 and the second gear mechanism 24 (see FIGS. 3 to 6) for translating the rotational movement of the motor shaft 16a and the first tool shaft 19 (see FIG. 3) into a corresponding rotational movement of the second tool shaft 23 about the rotational axis 12.

(14) The distal rear end 2b of the rear part 2a of the housing 2 is attached to or forms integral part with a battery pack 13 comprising the battery 14 and possibly other electric or electronic components. Upon insertion of the battery pack 13 into the rear part 2a of the housing 2 it is automatically connected to electric connectors 15, fixedly located inside the housing 2. Electric energy stored in the battery 14 is provided to the other electrical components of the polisher 1 via the connectors 15.

(15) The coupling of the coupling assembly 20 is such that torque is transmitted from the gear output shaft 18 to the first tool shaft 19. The tool shaft 19 is rotatably supported in the front part 2c of the housing 2 by bearings 21 such that it rotates about the rotational axis 22. In the shown embodiment the rotational axis 22 of the first tool shaft 19 is identical to a rotational axis of the gear output shaft 18 of the first gear mechanism 17. The rotational movement of the output shaft 18 and the first tool shaft 19, respectively, is transmitted to a second tool shaft 23 by the second gear mechanism 24. The second tool shaft 23 is rotably supported about the rotational axis 12 of the tool head 9 by bearings 25.

(16) Attached to the second tool shaft 23 is a functional unit 27 according to the present invention, which provides for a functional connection between the second tool shaft 23 and the working element 11. The functional unit 27 determines the type of actuating movement of the working element 11. To this end the functional unit 27 includes a carrier element 28 which holds the working element 11. Depending on the type and design of the functional unit 27 and the carrier element 28, respectively, the actuating movement of the working element 11 can include one or more of the following kind: a purely rotational, a random-orbital, a roto-orbital, a planetary, a linear and a linear or rotary alternating back-and-forth actuating movement. Furthermore, the functional unit 27 is detachably fixed to the rest of the tool 1, e.g. to a distal end of a tool shaft, for instance of the second tool shaft 23. The functional unit 27 and its attachment to the rest of the tool 1 are described in more detail with reference to FIGS. 5 and 6 below.

(17) The working element 11 can include a backing plate 11a, which is preferably made of expanded polyurethane and particularly resistant to mechanical stresses. A supporting structure 11b, for example made of metal or a rigid plastics material, is embedded into the top of the backing plate 11a. A bottom surface 11c of the backing plate 11a is provided with attachment mechanism, for example a hook-and-loop-fastener, a glued surface for mechanical adhesion, for removably attaching a working sheet, for example a polishing pad 11d made of a foamed material or microfiber, a polishing cushion made of wool or similar material, or an abrasive sheet material. Of course, the working element 11 and the backing plate 11a, respectively, could also be used directly for working a surface of a workpiece, without the need to attach a separate working sheet to the bottom surface 11c. In that case, the backing plate 11a and the bottom surface 11c could be designed such that they can directly perform a sanding or polishing operation on the workpiece surface or the working sheet could be integrally formed (e.g. by a molding process) on or inseparably attached (e.g. glued or welded) to the bottom surface 11c of the backing plate 11a.

(18) The user or operator of the tool 1 can replace a working sheet attached to the bottom surface 11c of the backing plate 11a (leaving the rest of the working element 11 attached to the tool 1). Alternatively or additionally the user can also replace the working element 11 in its entirety (leaving the rest of the functional unit 27 attached to the tool 1). Furthermore, alternatively or additionally the user can also replace the functional unit 27 in its entirety comprising the working element 11 and, if present, the working sheet 11d attached thereto. Of course, after replacing the functional unit 27 the previously used working element 11 and/or working sheet 11d could be re-attached to the new functional unit 27. Preferably, the bevel gear mechanism 24 cannot be replaced by a different gear mechanism. However, theoretically it could be possible to design the tool 1 such that the entire tool head 9 can be replaced, including the gear mechanism 24 and the functional unit 27 with the working element 11.

(19) FIG. 4 shows a detailed view of section IV of FIG. 3 including the tool head 9 and the functional unit 27 performing a purely rotational actuating movement. The functional unit 27 comprising the carrier element 28 and the working element 11 is releasably attached to the distal end of the second tool shaft 23 by a threaded connection 29. FIG. 5 shows the functional unit 27 of FIG. 4 detached from the rest of the tool 1. The functional unit 27 can be detached from the second tool shaft 23 by inhibiting rotation of the tool shaft 23 and contemporaneously rotating the functional unit 27 about the rotational axis 12, in order to loosen the threaded connection 29. The rotation of the second tool shaft 23 can be inhibited by pressing an appropriate brake or interference button 36 at the top of the tool head 9. Of course, inhibiting the rotation of the tool shaft 23 can be designed in any other appropriate form and can be located in any other appropriate position.

(20) As can be seen from FIG. 5, the threaded connection 29 includes an external thread 29a embodied on a shaft 30 of the carrier element 28. Furthermore, the threaded connection 29 comprises a second internal thread 29b located within a bore 31 at a distal end part of the second tool shaft 23. Preferably, seen from the bottom of the working element 11 or from the top of the tool 1, a direction 34 of the threaded connection 29 is opposite to a direction 35 of the rotational movement of the second tool shaft 23 about the rotational axis 12. In the embodiment shown in FIG. 4 the direction 35 of the rotational movement of the second tool shaft 23 seen from above is clockwise. The threaded connection 29 would go into the respective opposite direction 34, that is seen from above counter-clockwise. This has the advantage that during use of the tool 1, the connection between the functional unit 27, 27′ and the rest of the tool 1 is automatically fastened and will not loosen unintentionally. Alternatively, the direction 35 of the rotational movement of the shaft 23 could also be directed counter-clockwise, in which case the direction 34 of the thread would be clockwise. This allows a transmission of torque at least in the direction 35 of the rotational movement of the second tool shaft 23. Of course, the mechanism for releasably connecting the functional unit 27 to the rest of the tool 1, in particular to the second tool shaft 23, can be designed in any other appropriate manner, too.

(21) It can be clearly seen from FIG. 5, that the functional unit 27 includes the carrier element 28 and the working element 11. The carrier element 28 shown in FIG. 5 holds the working element 11 with a rotational axis 12′ of the working element 11 congruent with the rotational axis 12 of the second tool shaft 23. Hence, the working element 11 performs a purely rotational actuating movement around axis 12, 12′. In other words, the rotational axis 12 is the same for the second tool shaft 23, the shaft 30 of the carrier element 28 and the working element 11. To this end, the carrier unit 28 can be attached to the distal end of the tool shaft 23 in a torque proof manner and the working element 11 is attached in a torque proof manner to the carrier unit 28 as well. In the embodiments of FIGS. 1 to 5 the torque proof connections are effected by threaded connections comprising externally threaded rods being screwed into bores having corresponding internal threads.

(22) The functional unit 27 shown in FIG. 5 can be replaced by another functional unit 27′, like the one shown in FIG. 6. It can be clearly seen that in the embodiment of the functional unit 27′ of FIG. 6 the rotational axis 12′ of the working element 11 is not identical to the rotational axis 12 of the second tool shaft 23. Rather, the two rotational axes 12, 12′ run parallel to and spaced apart from one another. Furthermore, the carrier element 28′ forms an eccentric set, comprising an eccentric bearing 28a (e.g. one or more ball bearings or a double row ball bearing) and a spindle 33, adapted for receiving the working element 11. The spindle 33 is connected to the supporting member 11b of the working element 11 in a torque proof manner by a further threaded connection 32. Of course, there are many other possibilities for connecting the working element 11 to the spindle 33 in a torque proof manner. The spindle 33 could also be an integral part of the supporting member 11b of the working element 11. The spindle 33 is held freely rotatable about the rotational axis 12′ in the carrier element 28′ by the bearings 28a. Together, the rotational movement of the eccentric carrier element 28′ about the rotational axis 12 plus the possibility for the spindle 33 to freely rotate about the rotational axis 12′ determine the random orbital actuating movement of the working element 11. Hence, the functional unit 27′ of FIG. 6 has a carrier element 28′, which translates the rotational movement of the second tool shaft 23 about the rotational axis 12 into a random orbital actuating movement of the working element 11.

(23) Of course, the working element 11 of the functional unit 27′ of FIG. 6 could perform any other type of actuating movement, too, if the carrier element 28′ was designed accordingly. In any case, the actuating movement of the working element 11 of the functional unit 27′ of FIG. 6 is different from the actuating movement of the working element 11 of the functional unit 27 of FIG. 5. Hence, the polisher 1 can perform different types of actuating movements of its working element 11 simply by replacing the functional unit 27 by another functional unit, like the functional unit 27′ of FIG. 6.

(24) Each functional unit 27, 27′ can receive different working elements 11. For example, the functioning unit 27′, which performs a random orbital movement, can comprise circular working elements 11 with diameters of 30 mm or 50 mm. Similarly, an identical working element 11, for example a circular working element with a diameter of 70 mm, could be mounted onto the functional unit 27 performing the purely rotational movement of the working element 11, as well as onto the functional unit 27′ defining the random orbital movement.

(25) The invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the invention are possible in light of the above teachings. Therefore, within the scope of the appended claims, the invention may be practiced other than as specifically described.