Patent Application
20200122292
The present invention relates to a dust hood, which includes a flange for fastening the dust hood to a transmission extension housing of an angle grinder. The dust hood is equipped with a hood body for the purpose of covering a circular cutting wheel on both sides, at least in sections, and it is equipped with a suction connecting piece for connecting a suction hose. Removed substrate material may be extracted from the hood body via the suction hose.
Dust hoods of the type mentioned at the outset are generally known from the prior art. They are used to avoid dust propagation during cutting work to protect the health of a user of the angle grinder.
It is an object of the present invention to provide a dust hood, which establishes the basis for safe cutting operation.
The present invention provides that the dust hood includes a sensor unit, with the aid of which it is possible to detect whether the suction hose is connected to the suction connecting piece and/or whether a flap of the suction connecting piece is open.
The present invention includes the finding that angle grinders are placed into use both with dust extraction and without dust extraction during practical deployment, i.e., for example, during dry cutting. During dry cutting without dust extraction, a circular cutting wheel of the angle grinder typically rotates in a co-rotating rotational direction to keep removed substrate material away from the user of the angle grinder. During dry cutting with dust extraction, the cutting wheel is typically driven in a contra-rotating rotational direction, which ensures better control of the kerf. It has been found that the possibility of operating an angle grinder in different rotational directions may result in operating errors, which, in turn, represent an undesirable dust exposure for the user. This is the case, for example, if the flap of the suction connecting piece is open, and no suction hose is connected to the suction connecting piece.
The dust hood according to the present invention establishes a basis for avoiding operating errors of this type. The sensor unit provided according to the present invention may be routed to an angle grinder, for example for the purpose of predefining the rotational direction of the cutting wheel of the angle grinder. For example, if the flap of the suction connecting piece is open and no suction hose is inserted into the suction connecting piece, it is possible to automatically predefine a co-rotating rotational direction of the cutting wheel, which is typically selected when no dust extraction takes place. However, if the flap of the suction connecting piece is open and the suction hose is inserted into the suction connecting piece or is connected thereto, a contra-rotating rotational direction is preferably predefined, since a proper dust extraction may be ensured.
In a particularly preferred embodiment, the dust hood includes a signal line, via which a sensor signal originating from the sensor unit may be tapped, preferably for the purpose of predefining the rotational direction of the cutting wheel of the angle grinder.
It has been proven to be advantageous if the signal line is guided through the flange of the dust hood. One or multiple interfaces may be provided on the flange, for example on an inner surface of the flange, which correspond to one or multiple interfaces on the transmission extension housing of the angle grinder. In the simplest case, the interface may have one or multiple electrical contact areas.
It has proven to be advantageous if the sensor unit includes a hood contact, with the aid of which it is possible to detect whether the flap of the suction connecting piece is open or closed. Alternatively or additionally, the sensor unit may include a connecting piece contact, with the aid of which it is possible to detect whether the suction hose is connected to the suction connecting piece.
In a particularly preferred embodiment of the dust hood, the sensor unit includes a hood contact, with the aid of which it is possible to detect whether the dust hood is connected to the angle grinder. The sensor signal of a hood contact may be evaluated by the angle grinder, for example in such a way that a rotation of the cutting wheel is prevented if no dust hood is connected to the angle grinder.
Different embodiments of the flap contact, the connecting piece contact and the hood contact are conceivable. The flap contact, the connecting piece contact and/or the hood contact may thus be provided, for example, in the form of a switch, a pushbutton, a magnetic contact or a light barrier. A sensor unit may also have a combination of switches, pushbuttons or the like.
In a first preferred embodiment, the flap contact is provided in the form of an ON/OFF slide switch. The slide switch is preferably actuated by the flap of the suction connecting piece. The flap of the suction connecting piece is preferably shaped in such a way that the slide switch is actuated upon opening the flap. By actuating the slide switch, the signal line in the form of an electrical loop may be either opened or closed, and rotational direction control electronics of the angle grinder may be preferably activated on the basis of this purely electrical signal.
The flap contact and the hood contact may also be functionally integrated, for example in the form of an ON/OFF/ON toggle switch, which is preferably actuated by the flap of the suction connecting piece. For example, it may be provided that the closed flap presses the toggle switch into a first ON position, the opened flap presses the toggle switch into a second ON position and/or the toggle switch assumes the OFF position (for example the middle position) if the dust hood is not situated on an angle grinder. A mechanical transmission link between the flap and the flange may be provided within the dust hood, for example in the form of a mechanical plunger, so that the toggle switch may be situated on the connecting piece in the area of the flap and be simultaneously able to detect, in terms of the hood contact, whether the dust hood is connected to the angle grinder.
In another preferred embodiment, the flap contact and the connecting piece contact are provided in the form of two pushbuttons. It is preferably provided that the closed flap actuates the first pushbutton, and the second pushbutton is actuated when the suction hose is inserted into the suction connecting piece. The pushbuttons may be situated in such a way that, if the flap is open and the suction hose is not connected to the suction connecting piece, neither of the two pushbuttons is pressed, which preferably causes the rotational direction control electronics to prevent a rotation of the cutting wheel of the angle grinder. In another preferred embodiment, the sensor unit includes only the flap contact, preferably in the form of a pushbutton.
As mentioned earlier, the flap contact, the connecting piece contact and/or the hood contact may be provided in a variety of forms. The flap contact and the connecting piece contact may thus be provided in the form of two light barriers, a closed flap interrupting the first light barrier, an open flap and/or an inserted suction hose preferably interrupting the second light barrier. It may be provided that a rotation of the cutting wheel is prevented by the rotational direction control electronics when neither the first light barrier nor the second light barrier is interrupted.
In another embodiment, only the flap contact is preferably provided in the form of a light barrier. It may be situated in such a way that the opened flap of the suction connecting piece interrupts the light barrier, and the closed flap does not interrupt the light barrier.
In another embodiment, the flap contact and the connecting piece contact may be provided in the form of magnetic contacts, for example reed switches. A closed flap preferably closes a first magnetic switch. An inserted suction hose may close a second magnetic switch. It is preferably provided that neither of the magnetic switches is actuated when the flap is open and the suction hose is not inserted, and a rotation of the cutting wheel—with respect to the angle grinder—is prevented in this case.
The functions of the flap contact, the connecting piece contact and/or the hood contact described above may, of course, also be logically inverted.
The invention also provides an angle grinder, which includes a transmission extension housing for connecting a dust hood of the type described above, the angle grinder including rotational direction control electronics, which, when the dust hood is connected, are connected by signals to the sensor unit via an interface in such a way that the rotational direction of the cutting wheel of the angle grinder may be predefined or is predefined as a function of a sensor signal coming from the sensor unit.
It has proven to be advantageous if the rotational direction control electronics are designed to prevent a rotation of the cutting wheel if no dust hood is connected to the angle grinder.
The angle grinder is preferably a handheld power tool. The angle grinder is particularly preferably battery-operated, i.e. in particular without a power cord.
The invention also provides a method for operating an angle grinder, the angle grinder including a dust hood equipped with a suction connecting piece, and the method including the following steps:
Detecting whether a suction hose is connected to the suction connecting piece and/or whether a flap of the suction connecting piece is open with the aid of a sensor unit encompassed by the dust hood;
Controlling a rotational direction of the cutting wheel of the angle grinder as a function of the state detected by the sensor unit.
The method may be refined accordingly by the features described above with reference to the devices.
The invention also provides a handheld power tool system, which includes an angle grinder of the type described above and a dust hood of the type described above.
Other advantages result from the following description of the figures. The figures illustrate different exemplary embodiments of the present invention. The figures, the description and the claims contain numerous features in combination. Those skilled in the art will advantageously also consider the features individually and combine them to form other reasonable combinations.
In the figures, identical and equivalent components are provided with identical reference numerals.
Dust hood 100 includes a sensor unit 20, with the aid of which it is possible to detect whether a flap 45 of suction connecting piece 40 is open.
In the present illustrated exemplary embodiment, sensor unit 20 includes a flap contact 21, with the aid of which it is possible to detect whether flap 45 of suction connecting piece 40 is open or closed. Flap contact 21 is designed as an ON/OFF slide switch, which is situated on suction connecting piece 40 in such a way that the slide switch is actuated into the ON position when flap 45 is opened.
Dust hood 100 includes a signal line 80, via which sensor signal SL originating from sensor unit 20 may be tapped for the purpose of predefining the rotational direction for cutting wheel 220 of angle grinder 200.
Angle grinder 200 itself includes rotational direction control electronics 230, which are connected by signals to sensor unit 20 via an interface (cf.
In the exemplary embodiment illustrated in
If flap 45 is open, flap contact 21 in the form of a slide switch would be electrically closed, so that rotational direction control electronics 230 now activate angle grinder 200 in such a way that cutting wheel 220 is driven in contra-rotating rotational direction GGD in the case of a startup of angle grinder 200. This would correspond to a dry cutting with dust extraction. It should be noted that dust hood 100 in
However, this is the case in the exemplary embodiment in
If flap 45 is closed (illustrated here), flap contact 21 in the form of a pushbutton is actuated, i.e. electrically closed. The rotational direction predefinition made by rotational direction control electronics 230 indicates a contra-rotating rotational direction GGD of cutting wheel 220.
If flap 45 is open, and flap contact 21 in the form of the pushbutton is not actuated, i.e. is electrically open, the rotational direction predefinition depends on the switching state of connecting piece contact 23.
If suction hose 400 is inserted into suction connecting piece 40, connecting piece contact 23 in the form of the internal pushbutton is actuated, i.e. electrically closed. The switching state of flap contact 21 and connecting piece contact 23 is transmitted in the form of what is now purely electrical sensor signal SL to rotational direction control electronics 230, which now specifies a contra-rotating rotational direction GGD of cutting wheel 220.
However, if suction hose 400 is not inserted into suction connecting piece 40 while flap 45 is open, correspondingly configured rotational direction control electronics 230 cause a rotation of cutting wheel 220 to be prevented even if the angle grinder is actuated. This is the case since it must be assumed that the dust passing through open flap 45 would harm the user of angle grinder 200.
In the exemplary embodiment in
As is clearly apparent from
Finally,
| Number | Date | Country | Kind |
|---|---|---|---|
| 17167204.1 | Apr 2017 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/059652 | 4/16/2018 | WO | 00 |
