Patent Application
20240198478
The present invention relates to a power tool having a disk-shaped tool, wherein the tool is able to be fastened to a drive shaft of the power tool by means of a fastening nut, wherein the drive shaft is set up to transmit a torque of the drive to the tool.
Power tools having disk-shaped tools are known in the prior art. Examples of these are angle grinders or cut-off grinders by means of which surfaces can be ground or substrates can be severed. The disk-shaped tools are, in particular, grinding disks or cut-off disks which are used to carry out the corresponding work. The grinding disks or cut-off disks can be studded with diamond fragments in order to further improve the cutting performance of the tool.
It is customary for such grinding disks or cut-off disks to be fastened to the power tool by means of fastening nuts. In order to be able to ensure a high degree of operational reliability, these fastening nuts have to be tightened with high forces. This frequently requires the manufacturer of the power tool to provide corresponding aids, such as socket wrenches or screw wrenches, by means of which the grinding disks or cut-off disks can be fastened to the power tool. These aids are usually designed to be particularly small and compact and specially tailored to the nut to be fastened. However, it is a lesson of life that such additional aids frequently get lost, particularly given their small size. However, such a loss is particularly annoying and causes a lot of trouble because it is frequently the case that only a single suitable wrench for loosening or tightening the fastening nut is present on a construction site. The re-acquisition of a suitable aid for loosening or tightening a fastening nut can thus lead to a considerable delay and time loss on the construction site.
In order to counter the need for an aid needing to be carried along, it has been proposed in the prior art to use quick-clamping nuts which can be used without corresponding additional aids to fasten grinding disks or cut-off disks to a power tool. However, such quick-clamping nuts are very cost-intensive and require extra space for installation. As a result, the use of quick-clamping nuts can constitute a challenge precisely in compact devices. Moreover, the quick-clamping nuts can also get lost on a construction site, with the result that there would always be a need, in this case too, for additional replacement nuts to be carried along. However, this frequently does not occur for cost reasons, and therefore, in this case too, there can also occur delays and time losses.
It is an object of the present invention to provide a power tool in which a disk-shaped tool can be fastened without additional aids. Moreover, it would be welcome by those skilled in the art if, for fastening the tool, it would be possible for standard commercial, cost-effective and readily available fastening nuts to be used, in order to effectively avoid delays and time losses on the building site.
The present invention provides a power tool having a disk-shaped tool, wherein the tool can be fastened to a drive shaft of the power tool by means of a fastening nut, wherein the drive shaft is set up to transmit a torque of the drive to the tool. The power tool is characterized in that the power tool is set up to loosen or tighten the fastening nut by means of at least one torque impulse of the drive of the power tool. In other words, the fastening nut can be loosened or tightened by means of a torque impulse of the drive of the power tool. Preferably, the fastening nut can be loosened or tightened by means of at least one torque impulse of the drive of the power tool, wherein the torque impulses can be output in particular at a frequency of 1 to 10 Hz. It is preferable in the context of the invention that the power tool and its drive are set up to output a quick succession of torque impulses, wherein an output frequency can lie in a range from 1 to 10 Hz.
It is preferable in the context of the invention that the drive of the power tool comprises a motor. The inventor has recognized that, particularly in the case of drives which comprise an electronically commutated motor, such torque impulses can be generated by the power tool that are of sufficient strength for it to be possible with them to tighten or loosen a preferably standard commercial fastening nut. In this respect, the present invention makes use of a capability of the power tool in order to solve a technical problem that has remained unsolved up until now. It has not been taken into consideration by those skilled in the art until now in this context for torque impulses which can be generated by a drive of a power tool to be used to fasten or loosen fastening nuts. Rather, what has previously been assumed by those skilled in the art is that fastening nuts have to be tightened or loosened using additional aids specially provided for that purpose or that aids specially provided for that purpose can be dispensed with only if cost-intensive quick-clamping nuts are used for fastening the grinding disks or cut-off disks. The present invention provides a possibility with which the fastening of the disk-shaped tools can take place with preferably standard commercial, cost-effective and readily available fastening nuts without the need here to use special aids. As a result, the invention precisely takes a turn away from the prior art and the prejudices of those skilled in the art.
There is provision according to the invention that the grinding disk or cut-off disk can be fastened to a drive shaft of the power tool by means of a standard commercial fastening nut. Here, the drive shaft is set up to transmit a torque of the drive to the tool. There is also provision that the drive of the power tool comprises a motor, wherein the motor generates a torque for driving the disk-shaped tool. This torque can preferably be transmitted to the tool using the drive shaft. In a very particularly preferred embodiment of the invention, the motor is an electronically commutated motor which preferably constitutes a brushless drive of the power tool. The inventor has recognized that in particular an electronically commutated motor is capable of generating torque impulses by means of which a fastening nut can be tightened or loosened. In particular, the torque impulses generated by the brushless motor exhibit a sufficiently large power transmission or sufficiently large torque to ensure that a standard commercial fastening nut can be securely and stably tightened or to ensure, conversely, that a secure and stable connection between the fastening nut and the power tool can be released by means of the generated torque impulse.
It is preferable in the context of the invention that the fastening nut can be loosened or tightened without aids just by means of the torque impulse of the drive of the power tool. This capability represents an essential advantage of the present invention.
The motor of the power tool is preferably an electrically commutated motor. The drive of the power tool is preferably set up to output torque impulses in quick succession.
It is preferable in the context of the invention that the impulse or the torque impulse is used to generate a torque which is greater than the counter-torque which is generated by the mass inertia of the nut and of the disk-shaped tool connected with the nut, this connection preferably being mediated by frictional engagement. The impulse can be output several times per second depending on the configuration of the drive. It is preferable in the context of the invention that the impulses are output at a frequency in a range from 1 to 10 Hz. In other words, the impulses can be output from 1 to 10 times per second, for example. In yet other words, the power tool or its drive can be set up to output torque impulses in quick succession.
In a preferred embodiment of the invention, the power tool has at least one sensor for monitoring the torque impulses. In other words, it is preferable in the context of the invention that the power tool has a sensor for monitoring an output of the torque impulses. Preferably, the outputting of the torque impulse in the context of the present invention occurs in sensor-monitored fashion, that is to say using a sensor. The sensor can preferably be an incremental encoder, absolute value encoder, accelerometer and/or Hall sensor, without being limited thereto. The Hall sensor and the absolute value encoder are preferably set up to determine a rotary position of the motor. The at least one sensor is in particular set up to determine a change in rotary position of the motor.
It can also be preferable in the context of the invention that sensor-less feedback is provided in the motor, making it possible to determine therewith at what introduced energy a particular angle change of the motor is brought about. In other words, the sensor-less feedback can be used to detect the interaction or the dependency between the introduced energy and the thus brought-about angle change in the motor.
From the time profile of these variables it is possible to determine whether the nut has already been tightened or whether the nut has possibly loosened. In particular, it is possible by means of the rotary position change or the angle change of the motor to derive whether the nut has or has not already been fastened to the power tool. The inventor has recognized that the total inertia changes depending on whether the disk-shaped tool is connected to the output shaft or has become released from the output shaft. The use of sensor-less feedback is associated with the advantage that there is no need to use any sensors and that the complexity of the power tool is limited.
In a second aspect, the invention relates to a method for fastening a disk-shaped tool to a drive shaft of a power tool. The fastening method comprises the following method steps:
It is preferable in the context of the invention that, in the context of the method, standard commercial fastening nuts for fastening the tool to the power tool can be provided and used. The terms, definitions and technical advantages that have been introduced for the power tool preferably apply to the methods and to the use analogously. An advantage in the case of the method and of the power tool is that the power tool can practically carry out the method without assistance on the part of the user and retention of objects or items is no longer required. This allows a user of the power tool to maintain optimal hand freedom and to be able to perform other tasks using his or her hands, which remain free.
In a further aspect, the invention relates to a method for releasing a disk-shaped tool from a drive shaft of a power tool. The release method comprises the following method steps:
It is preferable in the context of the invention that, in the context of the release method, standard commercial fastening nuts can be provided and used. The outputting of the torque impulse preferably occurs in such a way that the fastening nut can be loosened from the drive shaft without further aids. In particular, the separation of power tool and tool occurs without tools or aids.
In yet a further aspect, the invention relates to the use of a torque impulse, which can be generated by a drive of a power tool, for tightening or loosening a fastening nut for fastening a disk-shaped tool to the power tool.
Further advantages will become apparent from the following description of the figures. The FIGURES, the description and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them to form useful further combinations.
In the FIGURES, identical and similar components are denoted by the same reference signs. In the drawing:
There is provision in the context of the invention that the power tool (1) is set up to loosen or tighten the fastening nut (3) by means of a torque impulse of the drive of the power tool (1). In other words, the fastening nut (3) can be loosened or tightened by means of a torque impulse of the drive of the power tool (1). The tightening of the fastening nut (3) preferably means, in the context of the invention, that the fastening nut (3) is fastened or fixed to the power tool (1). Preferably, the tool (2) interacts with a tool fitting (7) which is set up to receive the tool (2) and to fasten it to the power tool (1). In the context of the invention, the tool fitting (7) can also be referred to as an output shaft.
In a preferred embodiment of the invention, the power tool (1) can have at least one sensor (6) for monitoring an output of the at least one torque impulse. Preferably, the outputting of the at least one torque impulse for releasing or fastening the tool (2) occurs with the use of the at least one sensor (6). This preferably means, in the context of the invention, that the sensors (6) of the power tool (1) are set up to monitor the outputting of the at least one torque impulse by means of which the release or fastening of the tool (2) is brought about. The sensors (6) are capable in particular of detecting a position and/or an acceleration. It is preferable in the context of the invention that the at least one sensor (6) is arranged between the motor (5) and the electronics (9). The at least one sensor (6) can be connected in particular to the motor (5) of the power tool (1) or be present in the spatial vicinity thereof.
Preferably, the power tool (1) comprises operator-control elements (8) which are set up to initiate release or tightening of the tool (2) using the fastening nut (3). Consequently, the user advantageously has to hand a possibility of initiating the preferably aid-free fastening or release of the tool (2). The power tool (1) can also comprise electronics (9) which are preferably set up for evaluating data, which are determined by the at least one sensor (6), for evaluating inputs which are input via the operator-control elements (8) and/or for controlling the motor (5) and its power supply. For this purpose, the power tool (1) can comprise electrical connections (10) which are set up for connecting the operator-control elements (8), the electronics (9), the at least one sensor (6) and/or the motor (5).
| Number | Date | Country | Kind |
|---|---|---|---|
| 20181437.3 | Jun 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP21/65285 | 6/8/2021 | WO |
