EP3848160A1 - Method for providing boost function for an electric tool, and electric tool with motor - Google Patents

Abstract

The present invention relates to a method for providing a boost function for an electric tool, the electric tool having a motor. In a second aspect, the invention relates to a power tool with a motor. A special feature of the invention is that different speeds and torques can be set in the power tool as a function of different external conditions. In this way, different operating states of the power tool are preferably established. In particular, the invention can provide a boost function for the power tool. The boost function makes it possible to operate the power tool in a second operating state with a higher torque than in a first operating state.

Description

The present invention relates to a method for providing a boost function for an electric tool, the electric tool having a motor. In a second aspect, the invention relates to a power tool with a motor. A special feature of the invention is that different speeds and torques can be set in the power tool as a function of different external conditions. In this way, different operating states of the power tool are preferably established. In particular, the invention can provide a boost function for the power tool. The boost function makes it possible to operate the power tool in a second operating state with a higher torque than in a first operating state.

Background of the invention:

In the prior art, power tools, such as cutoff grinders, slitting devices or diamond cutoff grinders, are known, with which different areas of a masonry or a substrate can be separated from one another. In the case of the device types mentioned above by way of example, this is done by making a slot in the subsurface. The slot can act as a separating joint between different areas of the subsurface or serve to accommodate supply lines such as electrical cables. The device types mentioned above by way of example have a cutting disc as a tool, which is often also referred to as a "blade". The electrical devices have a motor with which the tool can be driven. The power tool is mostly operated by a rotational movement of the tool and is characterized by the speed of the motor. Power tools, such as the device types mentioned above, are usually operated at a fixed motor speed. This can be achieved, for example, in that a previously determined speed is preset for each device at the factory, which the user of the power tool cannot easily change.

In order to be able to cover a large number of application cases, this is a fixed engine speed, mostly based on the assumption of "ideal boundary conditions". These can be present, for example, when work is to be carried out in a homogeneous subsurface, the course of the cut is straight and only with little blade friction, especially on the sides of the tool of the electrical appliance, is to be expected. However, this can lead to problems when operating the power tool under real conditions. In particular, when less ideal boundary conditions occur, the torque available at the one previously determined speed set in the power tool may not be sufficient to maintain the desired - or required - speed and to be able to ensure efficient work progress. Less ideal boundary conditions can exist, for example, when working in an inhomogeneous subsurface, with an inclined cutting course or with high blade friction on the tool of the electrical device.

The object of the present invention is accordingly to provide a method for providing a boost function for an electrical device, with which the operation of the electrical device can be adapted to different applications and environmental conditions. In particular, a possibility is to be provided to be able to work with a sufficiently powerful electric tool in unfavorable external conditions. The provision of a power tool that can be operated for a certain period of time in a particularly powerful operating state is preferably referred to as a boost function of the power tool in the context of the invention. In addition to providing a corresponding method, a further object of the invention is also to provide a power tool which is set up to implement the boost method to be provided.

The object is achieved by the subject matter of the independent claims. Advantageous embodiments relating to the subject matter of the independent claims can be found in the dependent subclaims.

Description of the invention:

1. a) Betrieb des Elektrowerkzeugs in einem ersten Betriebszustand mit einer ersten Drehzahl n1 des Motors bei ersten äußeren Bedingungen,
2. b) Feststellen von zweiten äußeren Bedingungen, die sich von den ersten äußeren Bedingungen unterscheiden,
3. c) Einstellung eines zweiten Betriebszustand des Elektrowerkzeugs durch Einstellung einer zweiten Drehzahl n2 des Motors als Reaktion auf die geänderten äußeren Bedingungen.

The object is achieved by a method for providing a boost function for an electric tool, the electric tool having a motor. The procedure consists of the following steps:

1. a) Operation of the power tool in a first operating state with a first speed n1 of the motor under first external conditions,
2. b) Establishing second external conditions that differ from the first external conditions,
3. c) Setting a second operating state of the power tool by setting a second speed n2 of the motor in response to the changed external conditions.

In a second aspect, the invention relates to a power tool with a motor, the power tool being characterized in that a first or a second operating state of the power tool can be set by setting a first or a second speed of the motor, the setting of the first or second Engine speed takes place as a function of external conditions. According to the invention, it is particularly preferred that a first operating state of the power tool is set by setting the first speed n1 of the motor and that a second operating state of the power tool is set by setting the second speed n2, the setting of the first or second motor speed in Dependence on external conditions takes place. The setting of different speeds on the motor advantageously results in different torques for the operation of the power tool, so that an adjustability or adjustability of the torque of the power tool can advantageously be achieved by setting different speeds as a function of external conditions. The definitions, technical effects and advantages described for the method apply analogously to the power tool, and vice versa.

In the context of the invention, it is very particularly preferred that the motor is an electrically commutated brushless motor. Brush motors are usually mechanically commutated and they have a fixed, natural characteristic curve with load points when the speed of the motor is plotted against the torque. In contrast to brush motors, with brushless motors the load points in a speed-torque diagram can be essentially freely selected, at least within limits, via electrical commutation and a corresponding design of the motor. The power of the motor preferably remains the same or in a similar size range. Brush motors often only allow load points with low power or a mechanical gear must be provided for setting these load points. Such an undesirable, complex provision of a mechanical transmission can advantageously be dispensed with when using a brushless motor, since the brushless motor can, as it were, replace the mechanical transmission.

With the use of such preferably electrically commutated brushless drives for the power tool, it is possible for the power tool to be operated at different motor speeds. In this way, it is possible to react to different external conditions by adapting the motor speed of the power tool. This enables the power tool to be flexibly adapted to different applications and its field of application is expanded considerably. In addition, any work can be done with increased efficiency and the need to switch between different different power tools or device types is less frequent.

wobei der Buchstabe n für die Drehzahl des Motors, der Buchstabe M für das Drehmoment und der Buchstabe P für die Leistung des Elektrogeräts steht. Es ist im Sinne der Erfindung bevorzugt, dass der Term auf der rechten Seite der Gleichung stets einem im Wesentlichen konstanten Wert entspricht, vorzugsweise der Leistung P des Elektrowerkzeugs. Insofern stellt die obige Gleichung eine Verknüpfung der physikalischen Größen Drehzahl n und Drehmoment M miteinander dar, die sich entgegengesetzt proportional verhalten. Wenn der eine Wert reduziert wird, erhöht sich der andere Wert, und umgekehrt. Die Verknüpfung wird bei der vorliegenden Erfindung ausgenutzt, um eine Anpassungsfähigkeit des Elektrowerkzeugs an unterschiedliche äußere Gegebenheiten, sowie eine Boostfunktion für das Elektrowerkzeug bereitzustellen. Insbesondere wird mit der Erfindung eine Möglichkeit bereitgestellt, eine Boostfunktion für das Elektrowerkzeug durch den Anwender zu aktivieren, wenn mehr Drehmoment für die effiziente Durchführung einer Anwendung erforderlich ist. Dies kann beispielsweise bei ungünstigen äußeren Bedingungen der Fall sein, wenn sehr hartes oder dichtes Material bearbeitet wird oder in dem Material beispielsweise auf eine Bewehrungsstange getroffen wird. Insbesondere kann durch die Erfindung eine erhöhte Arbeits-Effizienz bereitgestellt werden, wobei diese erhöhte Arbeits-Effizienz insbesondere durch eine Anpassung der Leistungsaufteilung des Elektrowerkzeugs je nach Anwendungsbedingungen erreicht wird. Tests haben gezeigt, dass dem Elektrowerkzeug im Boostmodus überraschenderweise ein um mehr als 10 % höheres Drehmoment zur Verfügung gestellt werden kann als im ersten Betriebszustand.The different engine speeds preferably result in different torques with which the power tool is operated. In this respect, the invention surprisingly enables the power of the power tool to be divided in favor of a higher torque at a lower speed. The physical quantities "speed" and "torque" are linked to one another via the following relationship: $$\mathrm{P.}=\mathrm{n}\cdot \mathrm{M.}\cdot \mathrm{\pi }/\mathrm{30th}$$

where the letter n stands for the speed of the motor, the letter M for the torque and the letter P for the power of the electrical device. For the purposes of the invention, it is preferred that the term on the right-hand side of the equation always corresponds to an essentially constant value, preferably the power P of the power tool. In this respect, the above equation represents a link between the physical quantities speed n and torque M, which behave in opposite proportions. If one value is reduced, the other value increases, and vice versa. The link is used in the present invention to provide an adaptability of the power tool to different external conditions, as well as a boost function for the power tool. In particular, the invention provides a possibility of activating a boost function for the power tool by the user when more torque is required for an application to be carried out efficiently. This can be the case, for example, in unfavorable external conditions, when very hard or dense material is being processed or, for example, a reinforcing rod is encountered in the material. In particular, the invention can provide increased work efficiency, this increased work efficiency being achieved in particular by adapting the power distribution of the power tool depending on the application conditions. Tests have shown that, surprisingly, the power tool can be provided with a torque that is more than 10% higher in boost mode than in the first operating state.

In a preferred exemplary embodiment of the invention, the first external conditions can correspond, for example, to external boundary conditions for the operation of the power tool which enable uncomplicated, smooth and simple operation of the power tool. In the context of the invention, these external conditions are preferably referred to as ideal boundary conditions. You can, for example, by a homogeneous subsurface, an essentially straight cut and / or a low friction of the The tool of the power tool. A first engine speed n1 can preferably be assigned to these ideal boundary conditions. This first motor speed is preferably based on the relation P = n. M • π / 30 connected to a first torque M1. This first torque M1 is achieved by the power tool in particular when the power tool is operated under the first external conditions, ie ideal boundary conditions.

In a second method step, it can be determined that these external conditions have changed or have changed in an elapsed period of time, so that second external conditions are now present. It is provided in the context of the invention that the second external conditions differ from the first external conditions. The second external conditions can be more or less suitable for the operation of the power tool. In the exemplary embodiment of the invention described here, it is assumed that the second external conditions make working with the power tool more difficult. In the context of this exemplary embodiment, the second external boundary conditions are preferably referred to as “poorer boundary conditions”. They can be characterized, for example, by an inhomogeneous subsurface, an inclined cut and / or high friction of the tool of the power tool. The determination that the boundary conditions for the operation of the power tool have changed can be made by means of a suitable sensor system on the power tool. In the context of the invention, however, it can also be preferred that the determination is made by the user of the power tool himself. For example, he can perceive that the tool of the power tool has hit a reinforcing bar, so that the work progress of the power tool is made more difficult. It can also happen that you are working in an uneven or unevenly dense subsurface. In these cases, the user of the power tool can adapt the desired operating mode of the power tool to the currently existing or perceived load, in particular by causing the electrical device to switch from the first to the second operating state. This is preferably achieved in that the user causes the power tool to be operated at a second motor speed n2 instead of a first motor speed n1. This can greatly increase work efficiency. Switching between different operating states or different engine speeds can take place, for example, with a switching device or other input means. The second operating state can preferably be referred to as a boost mode, which is advantageously associated with a higher torque than that first operating state, which can be set on the electrical device, for example, under ideal boundary conditions.

The boost function can be activated, for example, when external conditions become more severe. This is preferably done by setting a second speed n2 in response to the changed external conditions. In the exemplary embodiment described here, the second speed n2 is lower than the first motor speed n1. In the context of the invention, it is very particularly preferred that the engine speed n and the torque M are linked to one another via the relation P = n • M • π / 30. To this extent, a reduction in the speed means that a larger second torque M2 can be made available for operating the power tool (“boost function”). In other words, in the context of the exemplary embodiment described here, it is preferred that the second torque M2 is greater than the first torque M1 with which the power tool is operated in the first operating state. It is particularly preferred that a greater torque can be provided in a second operating state than in a first operating state of the power tool. In the context of the present invention, the first operating state is preferably referred to as the ideal or standard operating state, while the second operating state is preferably referred to as the boost operating state.

When the power tool is operated in the second operating state, there are several options for continued operation. For example, a return to the first engine speed n1 is conceivable. This return can, for example, take place automatically after an adjustable period of time Δt. In the context of the invention, it can also be preferred that the external conditions of the power tool are monitored with a suitable sensor system, wherein the power tool can be set up, for example, to decide for itself whether the first or the second operating state as a function of the external conditions determined is set. For this purpose, the power tool can include a control device in which the measured values and data determined by the sensor system are processed and evaluated using information technology. In other words, it is preferred in the context of the invention that the power tool comprises a control device for the automatic setting of the operating state by the power tool itself. The control device is preferably set up to process and evaluate information with regard to the external conditions using information technology. The information regarding the external conditions is preferably determined by a sensor system, which can also be part of the power tool. In other words, it can be preferred in the context of the invention that the power tool comprises a sensor system with which the external conditions can be determined.

In the context of the invention, it can also be preferred that detection is carried out by operating patterns on the basis of existing operating measured variables. These operational measured variables can, for example, be electrical variables such as the current. The use of such a detection using operating patterns is particularly advantageous when detecting reinforcement hits, i.e. when steel is hit while drilling in a subsurface or masonry. It can furthermore be preferred in the context of the invention that the feed and / or the feed force is measured and / or evaluated. In addition, vibration patterns can be evaluated in the context of the present invention. Such an evaluation of vibration patterns is based on the inventors' knowledge that the power tool vibrates differently depending on whether the power tool tool has hit steel, for example, or whether the power tool tool is jammed, for example.

It can also be preferred in the context of the invention that a user decides in which operating state the power tool is operated. This decision by the user can, for example, be based on his or her subjective perception. In other words, depending on the external conditions perceived by him, the user can decide whether the first or the second operating state is to be set on the power tool. For this purpose, the power tool can have suitable and easily accessible switching devices or can be controlled via spoken commands or gestures. In other words, it is preferred in the context of the invention that the power tool comprises a switching device for setting the operating state. It can also be preferred in the context of the invention that the power tool comprises a corresponding input device for inputs by the user. This can be, for example, an operating screen, such as a touch screen, for the power tool.

For the purposes of the invention, however, it can also be preferred to continue the operation of the power tool at the second motor speed n2, for example until a point in time at which the first external conditions are determined again. This can be done automatically by a corresponding sensor system on the power tool or by the perception of a user of the power tool. Accordingly, it can be preferred within the meaning of the invention that the power tool, after recognizing that the first external conditions are present again, of its own accord, ie preferably automatically, returns to the first operating state in which the motor is operated at the first speed n1. In the context of the invention, however, it can also be preferred that the user switches between a first operating state with an engine speed n1 and a second operating state that is determined by an engine speed n2 is marked, can choose himself, for example by activating or releasing a corresponding switch on the power tool.

In the context of the invention, the term "boost function" means that a power tool can be operated for a short time above its actual performance limit in order to achieve a particularly high, but at least equally high, output in this short operating period, the boost mode particularly high torque M is characterized to work. A power tool in boost mode can be used, for example, to separate thin, particularly hard components of masonry from one another. However, many other types of work are also conceivable in which a boost function can significantly simplify the work of a user. With the present invention, in particular, a possibility for providing a boost function for an electrically commutated brushless motor of a power tool is presented.

For the purposes of the invention, it is preferred that a speed of the motor can be variably set as a function of external conditions. As a result, a torque of the power tool can advantageously also be changed. In the context of the invention, it is particularly preferred that a higher torque can be achieved and / or set when the speed is reduced. The provision of this higher torque is preferably referred to as a boost function in the context of the invention. A reduction in the speed preferably leads to an increase in the torque and an increase in the speed to a reduction in the torque of the power tool. In particular, the two variables "torque" and "speed" are linked to one another via the following relation: P = n • M • π / 30. In other words, the preferably essentially constant power of the power tool can be divided on the basis of the formula P = n • M • π / 30 take place.

For the purposes of the invention, it is preferred that the power tool is a slitting device or a cut-off grinder, which are usually made available in embodiments known from the prior art with a fixed motor speed. It represents a departure from the state of the art to provide such device types with different speeds and torques that can be set automatically or by the user in order to be able to react better and more flexibly to different application requirements and changes in external conditions.

It is preferred in the context of the invention that the electrical devices are provided with exactly two different speed options, so that a first and a second operating state of the electrical tool can be made possible. But it can in the sense of the invention It may also be preferred that a user can essentially continuously or fluently choose between a multiplicity of pair combinations of speed and torque. For example, three, four, five, six or more speed possibilities or combinations of speed and torque are also conceivable. The provision of the different combinations of speed and torque is achieved in particular through the design of the preferably brushless motor. If, for example, the motor can serve load points with the same output of + 10% torque, it is possible, for example, to provide two load points. The user can perceive an increase in torque of 10%, for example, and it typically also affects the progress of work. If a design of the motor can handle an increase in torque of more than + 10%, then, for example, three or more combinations of speed and torque can also be provided.

With the use of electrically commutated brushless drives for cutoff grinders or slitting devices, it is advantageously possible to split the power of the power tool in favor of a higher torque at a lower speed. The invention advantageously represents a possibility of activating the boost function by the user when more torque is required for the efficient implementation of the application. As a result, a high level of work efficiency can advantageously be achieved by adapting the power distribution depending on the application conditions.

In the context of the present invention, the highest possible speeds are preferably provided so that the electrical device for processing an average subsurface has a minimum amount of torque in order to cope with its task. In the context of the invention, it is preferred that a cutting power of the electrical device is determined by the speed if the torque is sufficiently high.

Further advantages of the invention emerge from the following description of the figures. In the figure, possible characteristics of a motor of a power tool are shown.

Fig 1

Ansicht möglicher Kennlinien für den Motor eines Elektrowerkzeugs

It shows:

Fig 1

View of possible characteristics for the motor of a power tool

Embodiment and description of the figures:

Fig. 1 shows a view of possible characteristics for the motor of a power tool. In particular, a first characteristic curve and a second characteristic curve are shown, which correspond to a relationship between the variables “torque” (horizontal axis) and “speed” (vertical axis). The two characteristic curves preferably correspond to the ratio of torque and speed in different operating states of the power tool. For example, the first characteristic curve can correspond to the standard operating state under ideal boundary conditions, while the second characteristic curve corresponds to the boost operating state of the power tool, which can be set or switched on in particular under difficult external conditions. It goes without saying that the in Fig. 1 The characteristic curves shown have been schematized and idealized.

For the purposes of the invention, it is preferred that the power of a power tool is determined by the physical quantities of torque and engine speed. The relationship between torque and speed can be understood using diagrams that contain characteristic curves, as in Fig. 1 shown. These characteristics are preferably obtained from points in the diagram that each correspond to a speed and a torque. The points that indicate a combination of torque and speed can also be referred to as the operating points of the power tool or its motor. With the present invention, the torque of a power tool can advantageously be shifted from low values (characteristic curve 1) to higher values (characteristic curve 2). This is preferably accompanied by a decrease in the motor speed, since the two variables torque and motor speed are preferably linked via the relation P = n • M • π / 30 (P: power of the electric tool, n: motor speed, M: torque). The shift in the torque to higher values takes place in the context of the present invention in particular as a reaction to changed external conditions which can influence the operation of the power tool. For example, the second operating state (“boost mode”) with the higher torque can be activated under more difficult ambient conditions, while the first operating state with the lower torque is set on the electrical device under normal or essentially ideal conditions.

It was surprising to experts that the working characteristic curve in a speed / torque diagram can be shifted in the manner described for an electrically commutated brushless motor of a power tool. The shift of the characteristic is shown in Fig. 1 indicated by the arrows. The vertical arrow pointing down in the left half of the picture represents the reduction in speed that can be associated with the change in the operating state from the first to the second operating state. For example, this change can correspond to switching from normal operation of the power tool to boost operation. The inclined, dashed arrow preferably symbolizes the increase in torque when switching the power tool from a first to a second operating state, for example when switching from normal to boost mode of the power tool.

Claims (9)

Method for providing a boost function for a power tool, wherein the power tool has a motor,
comprising the following steps: a) Operation of the power tool in a first operating state with a first speed n1 of the motor under first external conditions, b) Establishing second external conditions that differ from the first external conditions, c) Setting a second operating state of the power tool by setting a second speed n2 of the motor in response to the changed external conditions. Power tool with a motor
characterized in that
a first or a second operating state of the power tool can be set by setting a first or a second speed of the motor, the setting of the first or second motor speed taking place as a function of external conditions. Power tool according to Claim 2
characterized in that
a speed of the motor can be variably adjusted as a function of external conditions. Power tool according to Claim 2 or 3
characterized in that
The power is split based on the formula P = n • M • π / 30, where the letter P stands for the power of the power tool, the letter n for the speed of the motor and the letter M for the torque. Power tool according to one of Claims 2 to 4
characterized in that
the motor is an electrically commutated brushless motor. Power tool according to one of Claims 2 to 5
characterized in that
the power tool is a slitter or a power cutter. Power tool according to one of Claims 2 to 6
characterized in that
the power tool comprises a switching device for setting the operating state. Power tool according to one of Claims 2 to 7
characterized in that
the power tool comprises a control device for automatically setting the operating state by the power tool itself. Power tool according to one of Claims 2 to 8
characterized in that
the power tool includes a sensor system with which the external conditions can be determined.

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