Patent ID: 12196222

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG.1shows in perspective illustration a power tool1. The power tool1in the embodiment is designed as a vacuum/blower device. Accordingly, the power tool1can be operated in a vacuum mode as well as in a blower mode. Vacuum mode and blower mode are different operating modes of the power tool1.

FIG.2shows in a schematic illustration the power tool1that comprises a housing3, wherein the housing3encloses a drive motor4and a blower device2. The drive motor4drives in rotation a fan wheel which is arranged in the blower device2and is not illustrated in detail. In the embodiment, the drive motor4is an electric motor. The electric motor is supplied with power in particular by battery pack5. The battery pack5is inserted in a battery pack compartment which is open toward the outer side of the housing so that the battery pack5can be exchanged easily without having to open the housing3. However, the electric motor can be supplied also by electric lines with power. It can also be provided that the blower device2is driven by an internal combustion engine, in particular by a two-stroke engine or a mixture-lubricated four-stroke engine.

As illustrated inFIG.2, in operation of the power tool1the blower device2sucks in air through an intake opening6and blows the air out through blow opening7. In this context, an air flow9passes through the intake opening6in a first flow direction30. The air flows in the flow direction30from the environment29of the power tool1into an interior28of the housing3toward the blower device2. In the embodiment, the blower device2is designed as a radial blower device. The air flow9is thus deflected by the blower device2from the intake opening6via a blower spiral42toward the blow opening7. The air flow9exits the interior28of the housing3through the blow opening7in a second flow direction31. The first flow direction30and the second flow direction31are oriented transversely to each other.

As illustrated inFIGS.1to3, the power tool1comprises a handle36. The handle36is supported on the housing3. The handle36comprises a grip region38for gripping the handle36. The handle36is supported pivotably about pivot axis39at the power tool1and comprises a respective work position for vacuum mode and blower mode. Upon conversion of the power tool1from one operating mode into the other operating mode, the handle36is to be rotated, preferably by 180°, about its pivot axis39in order to provide the operator with an ergonomic handle position of the respective power tool1in the respective operating mode.

As illustrated inFIGS.1and3, the power tool1comprises a further arc-shaped handle37in addition to the handle36. The arc-shaped handle37and the blow opening7are arranged on opposite sides of the blower device2. In this way, the repulsion force of the air flow9exiting from the blower tube8can be absorbed very well by the operator by means of the handle37. The arc-shaped handle37is embodied substantially in a U shape. The two ends of the handle37are secured at opposite sides of the power tool1such that the handle37engages across the blower device2.

FIGS.1to3, show the power tool1mounted as a blower. The blow opening7is provided at an assembly socket32which is part of the housing3. In the blower mode of the power tool1, the blower tube8is arranged at the assembly socket32. Inside of the assembly socket32, a first guard10is provided (FIG.4). The first guard10is indicated schematically inFIG.2. The first guard10is formed as an ingress protection and prevents the operator of the power tool12from putting his hand through the blow opening7at the assembly socket32into the interior28of the power tool1.

As illustrated inFIGS.1to3, a second guard10′ is provided at the intake opening6in the blower mode of the power tool1. The second guard10′ is designed as a grid so that larger objects are blocked by the grid and cannot be sucked into the blower device2. In addition, the second guard10′ also provides an ingress protection. This is in particular important when a shredder33for shredding leaves is provided at the blower device2, as schematically indicated inFIG.2. In the blower mode of the power tool1, the air flow9flows from the environment29through the second guard10′ via the intake opening6into the blower device2. Subsequently, the air flows through the blow opening7into the blower tube8and from there into the environment29.

In the suction or vacuum mode, not illustrated in detail, of the power tool1, a collecting bag, for example, can be mounted on the assembly socket32at the blow opening7in place of the blower pipe8. In addition, at the intake opening6a suction tube is arranged. As illustrated inFIGS.1and2, the second guard10′ is fastened pivotably by means of a closure34and a hinge35at the housing3of the power tool1. For conversion of the power tool1from blower mode into vacuum mode, the closure34of the second guard10′ is to be opened. Subsequently, the second guard10′ can be pivoted into an open position and the suction tube can be pushed onto the intake opening6. In the vacuum mode of the power tool1, the air flow9flows through the suction tube and from there through the intake opening6to the blower device2. The air flow9exits the blower device2in flow direction31and flows through the blow opening7into the collecting bag. By means of the air flow9generated by the blower device2, objects such as leaves can be sucked in. As illustrated in the embodiment, it can be provided that a shredder33is disposed at the blower device2which shreds these objects so that the shredded objects can be collected in the collecting bag in compact form.

FIG.4shows a detail of the power tool1in demounted state. The blower tube8is detached from the assembly socket32. Thus, the blow opening7at the assembly socket32is visible. The assembly socket32is of a tubular configuration. In the embodiment, the cross section of the assembly socket32is circular (FIG.5). It can also be expedient to design the cross section in a different shape, for example, oval, rectangular etc. The assembly socket32comprises a circumferential wall41with an outer surface42facing the environment29and with an inner surface43facing away from the outer surface42. The first guard10is arranged in the assembly socket32. The first guard10is designed such that it is not possible for the operator to pass his hand through the assembly socket32.

As illustrated inFIG.4, the first guard10in the embodiment comprises two ribs11,15, namely a rib11and a further rib15. The ends of the two ribs11,15are attached to the inner surface42of the circumferential wall41of the assembly socket32, respectively. In the viewing direction coaxial to the assembly socket32, the ribs11,15are designed, preferably in a straight line and form chords of the circular cross section of the assembly socket32(FIG.5). In an alternative embodiment of the first guard10, the ribs11,15can also be arc-shaped. In the embodiment, the two ribs11,15each have a longitudinal direction12,12′ (FIG.5), wherein the longitudinal direction12of one rib11is different from the longitudinal direction12′ of the additional rib15. The two ribs11,15converge at a connection point22so that their longitudinal directions12,12′ at the connection point22intercept each other. Thus, the two ribs11,15provide a protection grid. It can also be expedient to arrange the two ribs11,15in such a way in the assembly socket32that they do not contact each other.

As illustrated inFIG.5, the longitudinal direction12′ of the additional rib15extends transversely, in particular orthogonally to the longitudinal direction12of the rib11. The connection point22of the two ribs11,15is positioned preferably approximately at the center of the cross section of the assembly socket32. Of course, the first guard10can also be comprised of only one single rib11. When the single rib11extends approximately through the center45of the cross section of the assembly socket32, the operator will also be prevented by the single rib11from passing his hand through the assembly socket32into the interior28of the power tool1. In addition, it is of course also understood that the first guard10can be comprised of more than two ribs11,15.

As illustrated inFIG.5, the rib11comprises at least one rib section13,14. In the preferred embodiment, the rib11comprises two rib sections13,14, namely a first rib section13and a second rib section14. It can also be expedient to provide more than two rib sections13,14. A rib section13,14extends along the longitudinal direction12of the rib11from a first end18to a second end19. In the embodiment, the first end18of the first rib section13is positioned at the circumferential wall41, the second end19of the first rib section13is positioned at the connection point22of the two ribs11,15. In the embodiment, the first end18′ of the second rib section14is positioned at the connection point22of the two ribs11,15, the second end19′ of the second rib section14is positioned at the circumferential wall41. A rib section13,14, depending on the outer excitation, can be excited to vibrate at its inherent modes, wherein the ends18,18′,19,19′ of the rib sections13,14form the mount points of a vibrating rib section13,14. Each rib section13,14comprises, considered by itself, its own inherent frequencies.

As illustrated inFIG.5, on at least one rib section13,14of the first guard10a disruptive body20that can translatorily vibrate is arranged. A disruptive body20that can translatorily vibrate is to be understood as a disruptive body which can at least vibrate translatorily. It is also possible that the disruptive body that can translatorily vibrate can also vibrate rotatorily in addition. A connection point22of two ribs11,15, on the other hand, constitutes no disruptive body20because the ribs11,15reinforce each other in such a way that a translatory vibration of the connection point22in the meaning of this application is not possible. A rotatory vibration of the connection points22is however possible. The disruptive body20forms together with the at least one rib section13,14a vibration system21with a system inherent frequency, wherein the system inherent frequency and the inherent frequency of the rib sections13,14are different. The first guard10is arranged in the assembly socket32so that the air flow9passes at higher flow rate through the first guard10. The air flow9provides an external excitation of the vibration-capable rib sections13,14. Due to the disruptive bodies20, a vibration system21is created whose system inherent frequencies are different compared to the excitation frequency of the external excitation. Thus, resonances at the rib sections13,14that lead to a high noise level are avoided. Therefore, a disruptive body20causes a frequency shift.

As illustrated inFIG.5, the additional rib15is also divided by the connection point22into two rib sections16,17, namely a top rib section16and a bottom rib section17. Thus, four rib sections13,14,16,17are provided in the embodiment, wherein at each rib section13,14,16,17at least one disruptive body20is arranged. In an alternative embodiment, it can be expedient to provide disruptive bodies20only at one, preferably only at two, in particular only at three, of the rib sections13,14,16,17.

As illustrated inFIG.5, only one disruptive body20is provided at the first rib section13of the rib11and only two disruptive bodies20are provided at the second rib section14of the rib11in the embodiment. In this way, the mass of the vibration system21comprised of the first rib section13and one disruptive body20is different compared to the vibration system21′ comprised of the second rib section14and two disruptive bodies20. The connection point22is fixed translatorily but forms a coupling point of the two vibration systems21,21′ which transmits rotatory vibrations. Due to the different masses of the two vibration systems21,21′, the two vibration systems21,21′ act on each other in a vibration-reducing manner.

As illustrated inFIG.5, only one disruptive body20is arranged at the bottom rib section17of the additional rib15. At the top rib section16of the additional rib15, on the other hand, only two disruptive bodies20are arranged so that the masses of the two vibration systems21″,21′″ are different. Thus, in analogy to the above explanation, a vibration-reducing effect occurs also. In the preferred embodiment, the rib sections13,14,16,17of a rib11,15each comprise a different number of disruptive bodies20. In this way, the masses of the vibration systems21,21′,21″,21′″ of a rib11,15are different.

It can also be provided that the disruptive bodies20of a rib11,15have masses of different magnitude. In this way, the vibration systems21,21′,21″,21′″ of a rib11,15can be provided with masses of different magnitude even for the same number of disruptive bodies20. Of course, the number of disruptive bodies20on the respective rib sections13,14,16,17of a rib11,15as well as the mass of the individual disruptive bodies20on the rib sections13,14,16,17of a rib11,15can be different.

As illustrated inFIG.5, a disruptive body20is designed as an elevation on a rib section13,14,16,17. The ribs11,15have, considered by themselves, a rib cross section that is preferably constant along their longitudinal direction12. Thus, an elevation that is projecting past the constant rib cross section is to be understood preferably as a disruptive body20. The disruptive body20is preferably embodied as an elongate, in particular rod-shaped, elevation on the rib section13,14,16,17.

As illustrated inFIG.6, the disruptive body20extends from its first longitudinal end25to its second longitudinal end26along a length direction27. The disruptive bodies20are preferably arranged such on the rib sections13,14,16,17that the length direction27of the disruptive body20is oriented approximately parallel to the flow direction31of the air flow9. Accordingly, the flow resistance of the disruptive body20is minimal. In order to further reduce the flow resistance of the disruptive body20, the longitudinal ends25,26of the disruptive body20are rounded aerodynamically, in particular in a drop shape.

In order to be able to modify the mass of the disruptive body20, the disruptive bodies20can be designed differently with regard to their geometry. Thus, it can be advantageous that the disruptive bodies20have different lengths in the length direction27of the disruptive bodies20and different widths. It can also be provided that the disruptive bodies20are comprised of different materials and thus also have different masses. In a preferred embodiment, the disruptive bodies20are however embodied of the same material, in particular of plastic material, as the ribs11,15so that the guard10can be manufactured in a simple manner. The guard10is preferably embodied as an injection-molded part. The disruptive body20and the rib11are preferably formed as one piece. Preferably, the guard10is of an one-piece configuration. The mass of the disruptive body20corresponds at least to 2%, in particular at least to 5%, preferably to approximately 8%, of the mass of a rib11,15. Preferably, the arrangement of a disruptive body20on a rib section13,14,16,17of a rib11,15effects an inherent frequency shift of at least 2%, preferably of at least 5%, advantageously of approximately 10%, in relation to the first harmonic and second harmonic of the respective rib section13,14,16,17.

In principle, the disruptive bodies20on the individual rib sections13,14,16,17are to be selected in regard to number and position in such a way that the inherent frequencies of the vibration systems21,21′,21″,21′″ are modified such that they do not create resonances with the excitation frequencies of the air flow9. In this context, it has been found to be advantageous that the vibration systems21,21′,21″,21′″ of neighboring rib sections13,14,16,17preferably have different masses or/and different relative centers of mass. In this way, a common vibration across the connection point22is prevented.

As shown inFIG.5, the two ribs11,15each have a top side23,23′ and a bottom side24,24′ opposite the top side23,23′. In the embodiment, at least one disruptive body20is arranged on the top side23,23′ and at least one disruptive body20on the bottom side24,24′ of the two ribs11,15. At the first rib section13of the rib11, a disruptive body20is arranged on the top side23of the rib11. At the second rib section14of the rib11, a disruptive body20is arranged on the bottom side24of the rib11; preferably, an additional disruptive body20is also arranged on the top side23of the rib11. In addition, at the bottom rib section16of the additional rib15, a disruptive body20is arranged on the top side23′ of the additional rib15. At the top rib section17, a disruptive body20is arranged on the bottom side24′ of the additional rib15; preferably, a disruptive body20is additionally arranged on the top side23′ of the additional rib15. Accordingly, in the embodiment, the number of disruptive bodies20on the neighboring rib sections13,14of a rib11or on the neighboring rib sections16,17of a rib15is preferably different. Moreover, it is advantageous to arrange the disruptive bodies20of two neighboring rib sections13,14or of two neighboring rib sections16,17also on different sides23,24or23′,24′ of the rib11or15.

As illustrated inFIGS.5and6, the disruptive bodies20of neighboring rib sections13,14of a rib11or neighboring rib sections16,17of a rib15in the embodiment are arranged asymmetrically to each other in relation to a plane46(FIG.6) which is oriented orthogonally to the respective rib11or15and intercepts the connection point22. The plane46extends parallel to the length direction27of the disruptive bodies20. In other words, the distances a, a′; b, b′ (FIG.5) measured in longitudinal direction of the respective rib11,15of two disruptive bodies20which are arranged on neighboring rib sections13,14,16,17are different.

As shown inFIG.6based on the example of rib11, the disruptive body20in the preferred embodiment is arranged such on the rib section13,14or16,17that, in the viewing direction perpendicularly to the top side23or23′ of the rib11or15, the disruptive body20is arranged inside of the rib11of15. Accordingly, the disruptive body20does not project past the rib11,15. In an alternative embodiment, it can also be expedient to design the disruptive body20such on the rib11,15that the disruptive body20projects past the rib11,15.

As illustrated inFIG.7, the disruptive bodies20can also be positioned differently with respect to their length direction27. The ribs11,15have a flow edge47facing the air flow9. The flow edge47extends in the preferred embodiment parallel to the longitudinal direction12of a rib11or15. The disruptive bodies20comprises a distance c, c′ in relation to the flow edge47. The distances c, c′ of two disruptive bodies20that are arranged on neighboring rib sections13,14or neighboring rib sections16,17of a rib11or15are different in the preferred embodiments.

InFIG.8, the power tool1is illustrated in a bottom view. In this view, the second guard10′ can be seen. The second guard10′ is designed as an intake grid and is significantly more fine-meshed than the first guard10. The fine-mesh guard10′ can also cause increased noise emissions due to occurring resonance vibrations. As indicated schematically inFIG.9, the rib sections of the ribs can also be provided with disruptive bodies20. In regard to the number and position of disruptive bodies20on the rib sections, the same principles as explained with respect to the first guard10apply and are also transferable onto the second guard10′. In principle, at each guard, in particular at each guard of a power tool1at which air flows effect a separate excitation and cause individual ribs or rib sections to vibrate, corresponding disruptive bodies20can be provided. This applies in particular also to cooling air grids for a cooling air flow for a drive motor4.

The specification incorporates by reference the entire disclosure of European priority document 21 156 954.6 having a filing date of Feb. 12, 2021.

While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.