Patent Application
20210229239
The present invention refers to a protective shroud for a hand-guided power tool, in particular a polisher or sander. The protective shroud is adapted to be attached to a housing of the power tool and to cover at least part of a working element of the power tool.
Further, the invention refers to a hand-guided power tool, in particular a polisher or sander, comprising a housing containing a motor, a working element driven by the motor and rotating about a rotational axis during operation of the motor and protruding at least partially from the housing, and a protective shroud being attached to the housing and covering at least part of the working element.
Power tools and protective shrouds of the above-identified kind are well-known in the prior art. For example, an angular polisher or sander comprises a housing, preferably made of plastic and containing a motor for driving a working element, which may be in the form of a backing pad. A polishing or sanding member may be releasably attached to a bottom surface of the working element, e.g. by means of a hook-and-loop fastener (Velcro®). The working element may have a circular, a rectangular, a triangular or a delta-shaped form. They may perform a purely rotational, an orbital or eccentric, a random-orbital or a roto-orbital (gear-driven) working movement. Depending on the type of working movement the working element exerts, different types of functional units may be interposed between a tool shaft driven by the motor and the working element. The functional units may comprise, e.g. a simple extension element, an eccentric element or a gear mechanism, in particular an epicyclic or planetary gear mechanism. The extension is attached to the tool shaft and the working element in a torque proof manner, in order to realize a purely rotational working movement of the working element corresponding to the rotational movement of the tool shaft. An eccentric element is attached to the tool shaft in a torque proof manner. The working element is supported in the eccentric element in a freely rotatable manner about its rotational axis. The rotational axes of the tool shaft and the working element extend essentially parallel and in a distance (the orbit or eccentric) to each other. If the working element is prevented from freely rotating about its rotational axis, an orbital or eccentric working movement of the working element may be realized. The eccentric element serves for realizing a random-orbital working movement. A gear mechanism serves for realizing a roto-orbital or gear-driven working movement.
The working element is at least partially covered by a protective shroud, which is usually mechanically fixed to the housing of the power tool. The protective shroud may serve a variety of purposes. First of all, it may serve to protect a user of the power tool from moving parts of the power tool protruding from the housing. These moving parts may comprise a distal end of the tool shaft, at least part of the functional unit and/or a part of the working element facing towards the housing, e.g. a top surface of a backing pad or a part thereof. Further, the protective shroud may serve as a dust collecting member for collecting at least part of the dust and small particles created on a working surface during intended use of the power tool. To this end, an inside cavity of the protective shroud is preferably attached to an internal dust extraction device of the power tool and/or an external dust extraction device, e.g. a vacuum cleaner. Furthermore, the protective shroud may serve as a braking member, for slowing down, impeding or even completely preventing a rotation of the working element about its rotational axis, when supported by an eccentric element in a freely rotatable manner. In this way, the random-orbital movement of the working element may be turned into an orbital or eccentric working movement.
The protective shroud is usually made of plastic material, preferably a soft plastic or synthetic rubber material or a rigid hard plastic material. It is usually attached to the housing of the power tool by means of a mechanical connection, e.g. by means of screws, a snap-on connection, a clamping connection or the like. Attachment and detachment of the protective shroud, in particular replacing the protective shroud, is complicated and time-consuming. In particular, separate tools (e.g. a screwdriver, a wrench or the like) are required for attachment and detachment of the protective shroud.
The object of the present invention is to provide for a protective shroud which can be attached to the housing of a power tool and detached from the housing fast and easy and which nonetheless may be attached to the housing in a safe and reliable manner.
This object is solved by a protective shroud comprising the features of claim 1. In particular, starting from a protective shroud of the above-identified kind, it is suggested that the protective shroud is secured to the housing in at least one direction by means of magnetic force.
This allows for a fast and easy attachment of the protective shroud to the housing of the power tool and detachment of the protective shroud from the housing, whenever desired. When during attachment bringing the protective shroud near a respective part of the housing, to which the protective shroud is to be attached, a magnetic force may act between the protective shroud and the housing and automatically secures the protective shroud to the housing. Similarly, the magnetic force may also act between two separate parts of the protective shroud. In order to detach the protective shroud from the housing simply the magnetic force has to be overcome. This can be easily effected by gripping the protective shroud and pulling it away from the housing or pulling two separate parts of the protective shroud apart. The attachment and detachment of the protective shroud may be effected without any separate tools.
The shroud may extend a full 360°-circumference around a rotational axis of the tool shaft or only part of the circumference, e.g. 270° or 180°. The shroud covers at least part of the working element. Preferably, the shroud also covers or surrounds at least part of a functional unit arranged between the tool shaft and the working element. The functional unit may comprise an eccentric element (for realizing a random-orbital working movement of the working element, if the working element is freely rotatable in respect to the eccentric element, or for realizing a purely orbital working movement, if free rotation of the working element in respect to the eccentric element is prevented) or a cylindrical extension element (for realizing a purely rotational working movement) or a gear arrangement (for realizing a gear-driven working movement).
The shroud may be provided with one or more magnetic elements facing the working element and adapted to interact with respective magnetic elements provided in a top surface of the working element (e.g. a backing pad) facing the shroud. The magnetic elements may comprise permanent magnets and/or ferromagnetic elements. Interaction of the magnetic elements creates a magnetic attraction force between the magnetic elements of the shroud and the magnetic elements of the working element, thereby slowing down or completely inhibiting a rotational movement of the working element about its rotational axis in respect to an eccentric element, in which the working element is supported in a manner freely rotatable about its rotational axis. By slowing down or preventing a free rotation of the working element about its rotational axis, a random-orbital working movement may be converted into a purely orbital working movement. In a power tool comprising a working element (e.g. a backing pad) with magnetic elements in its top surface, the working movement of the working element can be changed from a random-orbital movement to an orbital movement simply by replacing a shroud without magnetic elements (for the random-orbital movement) with a shroud equipped with magnetic elements (for the orbital movement).
Furthermore, the shroud may be provided with one or more light sources, preferably semiconductor light sources, in particular LEDs, which emit light. LEDs have the advantage that they have a low energy consumption and emit relatively bright light. The light sources are advantageously arranged such that the light is emitted to the front of the power tool, thereby allowing the user an easy and precise inspection of the surface to be worked or currently under work. The main direction of light emission is directed obliquely in respect to the surface extension of the working surface. It is suggested that the shroud is also provided with an electric energy source, e.g. a battery, for supplying the light source with electric energy. The electric energy source may also comprise some kind of generator or dynamo for inductively creating an electric current, due to the working movement of the working element in respect to the protective shroud. To this end, one or more permanent magnets of the working element may be used to induce electric current in one or more electric conductors of the shroud. The electric current induced in the conductor(s) may be used for charging the battery and/or operating the light sources. Alternatively, the battery may be replaced by a new (fully charged) battery. It would even be possible to replace the entire shroud with a new shroud with a light source and a fully charged battery. The light sources may be part of an adapter element or of the shroud itself. It would even be possible that the light sources may be operated by means of electric current from the power tool without the necessity of a separate battery and/or a dynamo or generator and/or an induction cable in the shroud.
The protective shroud according to the invention is particularly advantageous if the power tool is provided with the ability to interchange different types of functional units in order to achieve different working movements of the working element with the same power tool. For example, by exchanging a mere extension element with an eccentric element, the working movement can be changed from purely rotational to random-orbital. Furthermore, by exchanging an eccentric element having a first orbit or eccentric (e.g. 2 or 3 mm) with another eccentric element having a second orbit or eccentric (e.g. 12 mm), the size of the orbit or eccentric of a random-orbital working movement can be changed. Such a power tool is known, for example, from EP 3 012 068 A1, which is incorporated herein in its entirety by reference.
Furthermore, if the entire functional unit or part of it could even be omitted in a power tool, e.g. by directly attaching the working element to the tool shaft, replacement of the protective shroud or of part of it may become necessary. In particular, due to the missing functional unit the distance between the housing and the working element (e.g. the backing pad) may decrease requiring a flatter or lower protective shroud. Such a power tool is known, for example, from co-pending EP-application “Functional Unit for a Hand-Guided Power Tool and Power Tool with such a Functional Unit” having the same inventor and filed the same day as the present patent application. That application is also incorporated herein in its entirety by reference.
According to the invention, it is differentiated between attachment of the protective shroud to the housing of the power tool and securing of the shroud to the housing. Attachment of the shroud comprises the mere positioning of the shroud at a desired attachment position in respect to the housing. The shroud merely attached (but not secured) to the housing could be easily detached from the housing. In order to avoid an unintentional detachment of the shroud form the housing, the shroud is secured to the housing. While attachment of the shroud may be effected in any desired way, in particular mechanically, according to the invention securing of the shroud is effected by means of magnetic force.
Attachment of the protective shroud to the housing of the power tool may be effected, for example, by inserting part of the housing, to which the shroud is to be attached, into a respective receptacle of the shroud defined in its inside. Insertion of the housing into the receptacle may be effected in an axial direction running essentially parallel to the rotational axis of the tool shaft. The inserted part of the housing is secured inside the receptacle of the shroud by means of magnetic force, preferably acting between the shroud and the housing. Alternatively, the shroud may be designed as to encompass in a radial direction that part of the housing, to which the shroud is to be attached, the radial direction running essentially perpendicular in respect to the rotational axis of the tool shaft. The encompassed shroud is secured to the housing by means of magnetic force, preferably acting between separate parts of the shroud thereby clamping it around and in respect to the housing.
Hence, the magnetic force for securing the shroud to the housing may act in an axial direction, i.e. parallel to a rotational axis of the tool shaft, in particular between the shroud and the housing, or in a circumferential direction, i.e. about the rotational axis of the tool shaft, in particular between separate parts of the shroud. Preferably, the protective shroud has an essentially tube-like form with a longitudinal axis extending there through and the magnetic force acts in an axial direction parallel to the longitudinal axis. Alternatively, the protective shroud has an essentially tube-like form with a longitudinal axis extending there through and the magnetic force acts in a circumferential direction in respect to the longitudinal axis.
According to a preferred embodiment of the invention, it is suggested that the protective shroud is adapted to be directly attached to the housing of the power tool. In that case the magnetic force for securing the shroud to the housing acts directly between the shroud and the housing. To this end, appropriate magnetic elements are provided in the shroud and the housing. The magnetic elements could comprise permanent magnets and/or ferromagnetic elements. If the housing or the shroud is made of a ferromagnetic material, the housing or the shroud itself could be used as a ferromagnetic element.
Alternatively, it is suggested that the protective shroud is adapted to be indirectly attached to the housing of the power tool by means of an adapter element fixed to the housing. In that case the magnetic force for securing the shroud to the housing acts between the shroud and the adapter element, i.e. indirectly between the shroud and the housing. To this end, appropriate magnetic elements are provided in the shroud and the adapter element. The magnetic elements could comprise permanent magnets and/or ferromagnetic elements. If the adapter element or the shroud is made of a ferromagnetic material, the adapter element or the shroud itself could be used as a ferromagnetic element. The adapter element may be fixed to the housing in any possible manner, e.g. comprising mechanical fixation such as by means of a clamping connection, a snap-on or clip connection, a bayonet connection, a gluing or welding connection. In the following, when mentioning attachment of the shroud to the housing, this always comprises a direct attachment of the shroud to the housing as well as an indirect attachment by means of an adapter element fixed to the housing.
The protective shroud is preferably made of a plastic material, preferably a soft plastic or synthetic rubber material. Of course, the protective shroud could also be made of a rigid or hard plastic material, if desired. The material of the shroud is preferably resilient and elastic enough so that it can be bent open for attachment to the housing of the power tool or a respective adapter element fixed to the housing. Alternatively, the shroud could also comprise one or more hinge elements, a snap-on elements, or the like for bending open the shroud and for attachment to the housing of the power tool or an adapter element fixed to the housing. Magnetic elements for achieving the magnetic force for securing the shroud to the housing of the power tool or to an adapter element fixed to the housing, may be inserted into respective receptacles provided in the shroud, and fixed therein, e.g. by means of friction, gluing or welding or mechanical fixation (e.g. screws, rivets, etc.). The magnetic elements could also be fixed in the receptacles by closing the receptacles with a respective lid. Alternatively, the magnetic elements could also be integrated into the shroud during the manufacturing process of the shroud, e.g. by means of co-moulding.
Respective magnetic elements for achieving the magnetic force for directly or indirectly securing the shroud to the housing or the adapter element, may be inserted into respective receptacles provided in the housing or the adapter element, and fixed therein, e.g. by means of friction, gluing or welding or mechanical fixation (e.g. screws, rivets, etc.). The magnetic elements could also be fixed in the receptacles of the housing or the adapter element by closing the receptacles with a respective lid. Alternatively, the magnetic elements could also be integrated into the housing or the adapter element during the manufacturing process of the adapter element, e.g. by means of co-moulding.
According to a preferred embodiment of the invention, the protective shroud has an essentially tube-like form with a cavity defined in its inside adapted for receiving at least part of a functional unit and/or of a top surface of the working element when the protective shroud is attached to the housing of the power tool. A diameter of an external circumference of the tube-like protective shroud may increase towards an end of the shroud opposite to the end with which it is attached to the housing resulting in a larger diameter towards the working element. This permits arrangement of a cavity inside the protective shroud of particularly large dimensions for receiving, e.g. a functional unit with an eccentric element having a particularly large orbit.
According to a further embodiment of the invention, the protective shroud has an essentially tube-like form with a receptacle defined in its inside adapted for receiving at least part of the housing of the power tool or of an adapter element fixed to the housing. The receptacle is arranged at an end of the shroud with which it is attached to the housing. Preferably, the receptacle opens into the cavity for receiving or surrounding at least part of a functional unit and/or of a top surface of the working element when the protective shroud is attached to the housing of the power tool. The opening serves for allowing the tool shaft of the power tool and/or the functional unit to pass through the shroud. Changing the functional unit thereby provoking a different orbit of the working element (e.g. a backing pad) could make replacement or omission of the shroud or part of it necessary.
An opening of the receptacle is preferably arranged at an end of the protective shroud opposite to an end of the protective shroud where an opening of the cavity is arranged. The opening of the receptacle faces towards the housing and serves for receiving the housing or the adapter element. The opening of the cavity faces towards the working element and serves for receiving or surrounding the functional unit or part of it and/or part of the top surface of the working element (e.g. the backing pad).
The receptacle may be separated from the cavity by means of at least one abutment member, e.g. an abutment collar, extending radially inwards towards the longitudinal axis of the protective shroud. The abutment member serves for limiting an insertion movement of the housing or the adapter element into the receptacle and in order to provide for an attachment of the shroud to the housing or the adapter element in a predefined plane. Preferably, the plane extends essentially perpendicular in respect to the longitudinal axis of the shroud and the rotational axis of the tool shaft.
Preferably, the receptacle is adapted to receive at least part of the housing of the power tool or of the adapter element fixed to the housing in an axial direction parallel to a longitudinal axis extending through the protective shroud. Hence, according to this embodiment, the part of the housing or of the adapter element is inserted into the receptacle in the axial direction, i.e. along the longitudinal axis of the shroud. In this case, the magnetic force preferably acts in the axial direction between the shroud and the housing or the adapter element, respectively.
Alternatively, the receptacle is adapted to receive at least part of the housing of the power tool or of the adapter element fixed to the housing in a radial direction perpendicular to a longitudinal axis extending through the protective shroud. Hence, according to this embodiment, a bottom end of the front casing of the housing or of an adapter element fixed to the housing is inserted into the receptacle in the radial direction, i.e. obliquely to the longitudinal axis of the shroud. In this case, the magnetic force preferably acts in a circumferential direction between separate parts of the shroud.
It is suggested that the protective shroud has at least one lateral slit extending in an essentially axial direction parallel to a longitudinal axis extending through the protective shroud, the slit adapted for laterally opening the protective shroud and laterally encompassing at least part of the housing of the power tool or of the adapter element fixed to the housing in a radial direction perpendicular to the longitudinal axis extending through the protective shroud. The shroud may be bent open along the slit in order to provide for a lateral insertion opening through which that part of the housing or the adapter element, to which the shroud is attached, may be inserted in the radial direction. After insertion of the part of the housing or the adapter element, the shroud is brought into its original form again by approximating the two side walls of the shroud limiting the slit, thereby encompassing the respective part of the housing or of the adapter element. The slit is kept in a closed state by means of the magnetic force. Preferably, the magnetic force acts in a tangential direction in respect to the longitudinal axis of the shroud.
Alternatively, it is suggested that the protective shroud is made up of at least two separate shell-like elements, in particular exactly two half-shell-like elements, separated from each other by a vertical plane comprising a longitudinal axis extending through the protective shroud, adapted for separation of the shell-like elements and laterally encompassing at least part of the housing of the power tool or of the adapter element fixed to the housing in a radial direction perpendicular to the longitudinal axis extending through the protective shroud. The shroud may be separated into its two half-shell-like elements. The elements are laterally applied to that part of the housing or the adapter element, to which the shroud is attached, thereby covering the part. The side walls of the shroud limiting the vertical plane of separation are approximated, thereby encompassing the respective part of the housing or of the adapter element. The two half-shell-like elements are kept attached together by means of the magnetic force. Preferably, the magnetic force acts in a tangential direction in respect to the longitudinal axis of the shroud.
According to yet another preferred embodiment of the invention, it is suggested that the protective shroud comprises at least one protrusion or recess adapted for interacting with a corresponding recess or protrusion provided on the housing of the power tool or on an adapter element fixed to the housing, in order to prevent the protective shroud attached to the housing or to the adapter element from unintentionally slipping off the housing or the adapter element. For example, the housing or the adapter element may be provided with a circumferential radially extending collar member, which is inserted into a respective groove of the shroud, when the shroud is attached to the housing or the adapter element. The collar and/or the groove preferably extend in a plane obliquely or perpendicular to the longitudinal axis of the shroud.
According to yet another embodiment, the protective shroud has at least one protrusion or recess adapted for interacting with a corresponding recess or protrusion provided on the housing of the power tool or on an adapter element fixed to the housing in order to allow attachment of the protective shroud to the housing or to the adapter element in only one or more discrete rotational positions about a longitudinal axis extending through the protective shroud. For example, the housing or the adapter element may be provided with a protrusion which is inserted into a respective notch of the shroud, when the shroud is attached to the housing or the adapter element. The protrusion and/or the notch preferably extend in an axial direction parallel to the longitudinal axis of the shroud. This permits an attachment or insertion movement of the housing or the adapter element into the recess of the shroud in a direction essentially parallel to the longitudinal axis, but only in one or more certain discrete rotational positions, where the or all protrusions are aligned with one or more respective grooves. Alignment can be achieved by rotating the protective shroud in respect to the housing or the adapter element about the longitudinal axis of the shroud.
Further features and advantages of the present invention will be described in detail hereinafter with reference to the accompanying drawings. It is emphasized that the shown embodiments are purely exemplary and are not intended to limit the invention in any way. In particular, the present invention also comprises embodiments with only one or any possible combination of the features shown in the drawings and/or described hereinafter, even if such embodiments are not explicitly shown in the drawings and/or mentioned in the description. The drawings show:
The drawing includes
The power tool 1 includes a housing 2 which may be 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 including a distal rear end part 2b, and the front part 2c including 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 2 could also be made of a different rigid material, for example metal or carbon fibre. 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. The rear part 2a of the housing is preferably hollow and is adapted to receive various components of the power tool 1 as will be described in further detail hereinafter with reference to
The front part 2c of the housing 2 can be fixed to the rear part 2a of the housing 2 by screws, a threaded connection or a 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. Preferably, the front part 2c is made of metal, in particular aluminium or steel, and has an essentially tubular form. The front part 2c receives a first tool shaft 19 in a manner so as to allow its rotation about a rotational axis 22. To this end, one or more bearings 21, e.g. in the form of a ball race, may be provided inside the front part 2c which rotatably support the first tool shaft 19. The front casing 2e may also be made of metal, in particular aluminium or steel, and have an essentially tubular form. The front casing 2e receives a second tool shaft 23 in a manner so as to allow its rotation about a rotational axis 12. To this end, one or more bearings 25, e.g. in the form of a ball race, may be provided inside the front casing 2e, which rotatably support the second tool shaft 23.
A tool head 9 is located at 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, a threaded connection 2f or a similar attachment mechanism. The tool head 9 comprises the front casing 2e and a working element 11 adapted for working a surface of a workpiece during intended use of the power tool 1.
The working element 11 may comprise a backing pad 11a to which a sanding member 11e (see
The rear part 2a of the housing 2 includes an actuation lever 4 co-operating with a switch for turning on and off the power tool 1. The switch is preferably located inside the rear part 2a of the housing 2. The actuation lever 4 may be provided on the top side (see
The distal rear end 2b of the rear part 2a of the housing 2 can be removed in order to withdraw at least one battery 14 (see
The battery pack 13 provides the power tool 1 and its electronic components, respectively, with electric energy necessary for their operation. Upon insertion of the battery pack 13 into the rear part 2a of the housing 2 the one or more batteries 14 are 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. Of course, the power tool 1 could also be operated with electric energy from a mains power supply. In that case the battery pack 13 would not be necessary and the receptacle for the battery pack 13 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 power tool 1.
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. Of course, other types of electric motors 16, e.g. an AC-motor, could also be used. In the shown embodiment of
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 the second tool shaft 23 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 97°-98°. The second tool shaft 23 eventually drives the working element 11. It is suggested that the second gear mechanism 24 includes a bevel gear with two bevel gear wheels 26. The gear ratio of the second gear mechanism 24 can be 1, larger than 1 or smaller than 1. The second gear mechanism 24 is preferably located in the tool head 9 of the power tool 1, in particular in the front casing 2e of the housing 2.
In contrast to the embodiment of
Furthermore, at least one 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, in particular inside the rear part 2a of 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 executed on the microprocessor. The power tool 1 may comprise one or more LEDs 6b, which indicate the current load status of the batteries 14. In this embodiment the one or more LEDs 6b are attached to the PCB of the control unit 6a. Light emitted by the LEDs 6b may pass through a transparent window 6c provided in the rear part 2a of the housing 2. For example, the one or more LEDs 6b may emit green light, when the load status is between 100% and 75%, yellow light, when the load status is between below 75% and 50%, red light, when the load status is below 50%, and flashing red light, when the load status is below 25%.
The power tool 1 comprises a functional unit 27, which is releasably attached to the second tool shaft 23. The functional unit 27 comprises a base element 28, a first attachment member 29 for releasable attachment of the base element 28 to the motor driven tool shaft 23 of the power tool 1, the working element 11, and a second attachment member 30 for attachment of the working element 11 to the base element 28.
The first attachment member 29 may be in the form of a hexagonal recess. It is adapted to releasably attach the base element 28 of the functional unit 27 to the tool shaft 23 of the power tool 1 by means of mechanical force (e.g. by means of a threaded connection) and/or magnetic force (see
The second attachment member 30 may comprise a protruding hexagonal element. It is adapted to releasably attach the working element 11 to the base element 28 of the functional unit 27 by means of mechanical force (e.g. by means of a threaded connection) and/or magnetic force (see
Depending on the type of functional unit 27 interposed between the tool shaft 23 and the working element 11, the working element 11 performs different types of working movements. For example, it may perform a purely rotational, an orbital or eccentric, a random-orbital or a roto-orbital (gear-driven) working movement. The functional units 27 may each comprise a base element 28 having the form of a simple extension element 28a (see
The working element 11 is at least partially covered by a protective shroud 40, which—in the prior art—is mechanically fixed to the housing 2 of the power tool 1, in particular to a bottom end 46 of the front casing 2e. The protective shroud 40 may serve a variety of purposes. First of all, it may serve to protect a user of the power tool 1 from moving parts of the power tool 1 protruding from the housing 2. These moving parts may comprise part of the tool shaft 23, at least part of the functional unit 27 and/or a part of the working element 11 facing towards the housing 2, e.g. a top surface 11b of a backing pad 11a. Further, the protective shroud 40 may serve as a dust collecting member for collecting at least part of the dust and small particles created during intended use of the power tool 1. To this end, an inside cavity 52 of the protective shroud 40 may be attached to an internal dust extraction device of the power tool 1 and/or an external dust extraction device, e.g. a vacuum cleaner (not shown). Furthermore, the protective shroud 40 may serve as a braking member, for slowing down, impeding or even completely preventing a rotation of the working element 11 about its rotational axis 12′, when supported by an eccentric element 28b in a freely rotatable manner. In this way, the random-orbital movement of the working element 11 may be turned into an orbital or eccentric working movement.
The protective shroud 40 is preferably made of plastic material, in particular a soft plastic or synthetic rubber material. However, it could also be made of any other material, e.g. a hard plastic material. In the prior art the protective shroud 40 is attached to the housing 2 of the power tool 1 by means of a mechanical connection, e.g. by means of at least one screw, rivet, a snap-on connection, a clamping connection or the like. In contrast thereto, the present invention suggests that the protective shroud 40 is directly or indirectly secured to the housing 2 in at least one direction by means of magnetic force. The shroud 40 according to the invention can be attached to the housing 2 of the power tool 1 and detached therefrom fast and easy. Still, the shroud 40 is attached to the housing 2 in a safe and reliable manner.
The present invention is described in connection with a special small-sized power tool 1 with an interchangeable functional unit 27, like the one shown in
In
An abutment member 45 comprising at least one circumferential collar member is provided on an internal wall of the receptacle 44. The abutment member 45 extends radially inwards towards the longitudinal axis 12″ of the protective shroud 40. When inserting the bottom end 46 of the front casing 2e of the housing 2 into the receptacle, the bottom end 46 may abut against the abutment member 45. Hence, the protective shroud 40 is attached to the housing 2 in a defined plane extending parallel to the extension of the abutment member 45, i.e. essentially perpendicular to the insertion direction 42 and to the rotational axis 12 of the tool shaft 23 and to the longitudinal axis 12″ of the shroud 40. Hence, the shroud 40 is mechanically attached to the housing 2 in the two-dimensional plane.
The protective shroud 40 is secured to the housing 2 in an axial direction by means of magnetic force 47. To this end, magnetic elements and/or ferromagnetic elements are provided in the shroud 40 (elements 48) and the housing 2 (elements 50). The shroud 40 and the housing 2 can both be provided with magnetic elements 48, 50 or one of them with magnetic elements 48 and the other one of them with ferromagnetic elements 50. If one of the two is made of ferromagnetic material, e.g. if the housing 2 is made of iron or steel, there would be no need for additional ferromagnetic elements 50 but the housing 2 itself could be used as ferromagnetic element instead. In
In the embodiment of
In order to allow insertion of the bottom end 46 of the front casing 2e into the receptacle 44, the protective shroud 40 comprises a lateral slit 58 extending parallel to the longitudinal axis 12″ of the shroud 40 and to the rotational axis 12 of the tool shaft 23. The shroud 40 is preferably made of a plastic material, in particular a resilient and/or elastic material, and can be bent open along the slit 58 thereby increasing the diameter of an upper insertion opening into the receptacle 44 of the shroud 40 and allowing the protrusion 54 to be inserted into the receptacle 44. If the bottom end 46 of the front casing 2e has been inserted far enough into the receptacle 44, the protrusion 54 can enter into the recess 56. Thereafter, the shroud 40 can be bent together again along the slit 58 thereby holding the protective shroud 40 in respect to the housing 2 of the power tool 1 in a plane extending parallel to the extension of the recess 56 and in a direction extending perpendicular in respect to the plane. Hence, the shroud 40 is mechanically attached to the housing 2 in a defined three-dimensional space.
In order to secure the protective shroud 40 to the housing 2, magnetic force 59 is used. To this end, it is suggested that the magnetic force 59 acts in a tangential direction in the region of the slit 58. The magnetic force 59 urges the slit 58 and the shroud 40, respectively, in a closed position, thereby avoiding an unintentional opening of the shroud 40 along the slit 58 and detachment of the shroud 40 from the housing 2. To this end it is suggested that the shroud 40 comprises magnetic elements 48, 50 one on each side wall limiting the slit 58 on opposite sides of the slit 58 and facing each other. Alternatively, one or more magnetic elements 48 can be provided on one side of the slit 58 and one or more ferromagnetic elements 50 can be provided on the other side of the slit 58. The magnetic or ferromagnetic elements 48, 50 can be located inside the side wall of the shroud 40, in particular of the chamber 52, or in external protrusions 60 provided externally on the side wall of the shroud 40, in particular of the chamber 52. Preferably, the protrusions 60 form an integral part with the side wall of the shroud 40 and are designed therewith in a single part.
The embodiment of
The protective shroud 40 may be attached to the adapter element 41 and secured thereto by magnetic force 47. To this end, the adapter element 41 may comprise an insertion section 62 and the shroud 40 comprises a second receptacle 44.2 adapted for receiving the insertion section 62. The insertion section 62 can be inserted into the receptacle 44.2 in a direction opposite to the insertion direction 42. Preferably, both the insertion section 62 and the receptacle 44.2 have a circular cross section. Hence, the protective shroud 40 may be attached to the adapter element 41 and, hence, indirectly to the front casing 2e of the housing 2 in any desired rotational position about the longitudinal axis 12″. Preferably, the protective shroud 40 is adapted to be attached to the adapter element 41 in only one rotational position. The adapter element 41 and the shroud 40 are preferably made of the same material. The material may be, for example, a hard plastic material, a soft plastic material and/or natural or synthetic rubber.
The insertion section 62 of the adapter element 41 forms a cylindrical insertion element and the second receptacle 44.2 of the shroud 40 forms a hollow cylinder. The receptacle 44.2 has an internal cross section corresponding to the external cross section of the insertion section 62. Preferably, the cylindrical receptacle 44.2 and the cylindrical insertion section 62 have the rotational axis 12 of the tool shaft 23 of the power tool 1 as well as the longitudinal axis 12″ of the shroud 40 as their cylinder axes. A bottom surface or collar 45 of the second receptacle 44.2 may serve as an abutment member for the adapter element 41 when inserted into the receptacle 44.2. When the insertion section 62 is inserted in the receptacle 44.2, the protective shroud 40 is mechanically attached to the housing 2 in a defined two-dimensional plane extending essentially perpendicular to the insertion direction 42 and to the rotational axis 12 of the tool shaft 23 and to the longitudinal axis 12″ of the shroud 40.
The protective shroud 40 is secured to the adapter element 41 in an axial direction by means of magnetic force 47. To this end, magnetic elements 48 and/or ferromagnetic elements 50 are provided in the adapter element 41 and the shroud 40. The adapter element 41 and the shroud 40 can both be provided with magnetic elements 48, 50 or one of them with magnetic elements 48 and the other one of them with ferromagnetic elements 50. If one of the two is made of ferromagnetic material, e.g. if the adapter element 41 is made of iron or steel, there would be no need for separate ferromagnetic elements 48 but the adapter element 41 itself could be used as ferromagnetic element instead. In
The embodiment of
When the two half-shell-like elements 40.1, 40.2 are close together, the magnetic force 59 enters into action and attracts the two elements 40.1, 40.2 thereby securing the shroud 40 to the adapter element 41 and, hence, indirectly to the housing 2. The elements 40.1, 40.2 comprise lateral protrusions 60 holding or containing the magnetic elements 48 and/or the ferromagnetic elements 50. The protrusions 60 are provided on opposing sides of the vertical plane separating the two elements 40.1, 40.2. The magnetic force 59 acts in a tangential direction, similar to what was previously described in respect to
The two half-shell-like elements 40.1, 40.2 may comprise one or more notches 64 adapted for receiving one or more corresponding protrusions 66 provided on the insertion section 62 of the adapter element 41 or the front casing 2e of the housing 2. One notch 64 for receiving one protrusion 66 allows attachment of the half-shell-like elements 40.1, 40.2 or of the protective shroud 40, respectively, in only one discrete rotational position about the longitudinal axis 12″ of the shroud 40 and the rotational axis 12 of the tool shaft 23. Of course, if the adapter element 41 or the front casing 2e of the housing 2, respectively, and the shroud 40 comprise more than one notch 64 and/or protrusion 66, respectively, distributed along the circumference of the insertion section 62 and the second receptacle 44.2, respectively, the shroud 40 could be attached in more than one discrete rotational position about the rotational axis 12 or the longitudinal axis 12″.
Mounting of the shroud 40 in one or more discrete rotational positions in respect to the housing 2 is preferably realized if the rotational mounting position of the shroud 40 about the rotational axis 12 or the longitudinal axis 12″ is important for further functionalities of the power tool or the shroud 40, respectively. This may be the case, for example, when the shroud 40 carries permanent magnets (see
The protrusions 66 could have a longitudinal extension in an axial and/or radial and/or circumferential direction. The notches 64 will preferably have a corresponding form and extension, in order to permit attachment of the shroud 40 to the adapter element 41 in one or more discrete rotational positions.
Of course, the one or more notches 64 could just as well be provided at the adapter element 41 or the front casing 2e of the housing 2, respectively, and, consequently, the one or more protrusions 66 would be provided at the protective shroud 40.
Hence, in the embodiment of
In all embodiments of
In
In the embodiment of
Finally, in the embodiment of
It can be clearly seen that the bottom end 46 comprises one or more recesses 82, 84. A first recess 82 has a longitudinal extension running essentially parallel to the rotational axis 12 of the tool shaft 23. The shroud 40 or the adapter element 41 has a corresponding protrusion (not shown) which is inserted into the recess 82 upon attachment of the shroud 40 or the adapter element 41 to the housing 2. The first recess 82 permits (in cooperation with the corresponding protrusion of the shroud 40 or the adapter element 41) attachment of the shroud 40 or the adapter element 41 to the housing 2 only in a discrete rotational position.
Further, a second recess 84 is provided at the bottom end 46 of the front casing 2e of the housing 2. The second recess 84 has an essentially circular form. The shroud 40 or the adapter element 41 has a corresponding protrusion (not shown) which is inserted into the recess 84 upon attachment of the shroud 40 or the adapter element 41 to the housing 2. The protrusion and the circular recess 84 form part of a snap-on connection which may serve for holding the protective shroud 40 or the adapter element 41 in the attached position on the housing 2. Additionally, the shroud 40 may be secured in respect to the housing 2 either directly or indirectly (by means of the adapter element 41) in at least one direction by means of magnetic force 47, 59.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 153 380.9 | Jan 2020 | EP | regional |
