The present invention relates to a method for the open-loop and closed-loop control of a power tool with at least one rechargeable battery, a drive and at least one control device, the rechargeable battery serving as an energy supply for the power tool.
In addition, the present invention relates to a system comprising a power tool and at least one rechargeable battery for supplying the power tool with electrical energy for carrying out the method according to the invention.
When using a rechargeable battery as a power supply for a power tool, the problem arises that the rechargeable battery is heated up by the internal resistance (also referred to as the output resistance) of the rechargeable battery cells when the electrical energy is delivered. For safety reasons, the delivery of the electrical energy from the rechargeable battery is ended when the rechargeable battery cells reach or exceed a critical temperature threshold value. The disadvantage here is that, when the temperature threshold value is reached, the rechargeable battery is often not yet fully discharged or there is still capacity (electrical voltage) in the rechargeable battery cells, which however is no longer available to the user of the power tool. In other words: due to the premature overheating of the rechargeable battery cells, the full capacity of the rechargeable battery cannot be used.
It is an object of the present invention provide a method for the open-loop and closed-loop control of a power tool with at least one rechargeable battery by which the aforementioned problem is solved and it can be ensured that the most effective possible use is made of the available capacity of a rechargeable battery as an energy supply for a power tool before the rechargeable battery cells overheat.
The present invention provides a method for the open-loop and closed-loop control of a power tool with at least one rechargeable battery, a drive and at least one control device, the rechargeable battery serving as an energy supply for the power tool.
According to the invention, the method comprises the method steps of
According to an advantageous embodiment of the present invention, it may be possible for the method to comprise the method steps of
According to an advantageous embodiment of the present invention, it may be possible that the performance parameter of the power tool is a speed value of the drive or a torque value of the drive.
Furthermore, the present invention provides a system comprising a power tool and at least one rechargeable battery for supplying the power tool with electrical energy for carrying out the method.
Further advantages can be found in the following description of the figures. Various exemplary embodiments of the present invention are shown in 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 into useful further combinations.
In the figures:
According to an alternative embodiment of the present invention, the power tool 2 may not be supplied with electrical energy by at least one rechargeable battery but by a network connection. The network connection may also be referred to as a power cable. This alternative embodiment of the present invention is not shown in the figures.
As illustrated in
The power tool 2 designed as a rechargeable battery-operated screwdriver substantially comprises a housing 4, a handle 5, a base part 6, a tool fitting 7, an electrical drive 8 in the form of an electric motor, a control device 9, a transmission 9a, an input shaft 11, an output shaft 12 and an activation switch 13.
The electrical drive 8 designed as an electric motor, the transmission 10, the input shaft 11, the output shaft 12 and the control device 9 are positioned in the housing 4. The drive 8, the transmission 10, the input shaft 11 and the output shaft 12 are positioned in relation to one another and in the housing 10 such that a torque generated by the drive 8 is transmitted to the output shaft 12. The output shaft 12 transmits the torque to the transmission 10, which in turn passes on a torque to the input shaft 11. The tool fitting 7 is driven by way of the input shaft 11 by the transmission of the torque. As illustrated in
As also shown in
As can also be seen from
The control device 9 of the power tool 2 comprises a microcontroller 18 (also referred to as an MCU) and a data interface with a first transceiver as part of a communication circuit for communication (i.e. data and signal exchange) between the rechargeable battery 3 and the power tool 2.
The rechargeable battery 3 essentially comprises a housing 21 with a rechargeable battery interface 22, a plurality of energy storage cells 23, control electronics 24 and a temperature measuring device 27. The control electronics 24 in turn comprise a microcontroller 25, a voltage measuring device 26 and a memory device 28.
The temperature measuring device 27 may also be referred to as a temperature sensor.
The rechargeable battery 3 also comprises a data interface with a second transceiver as a component part of a communication circuit for communication between the rechargeable battery 3 and the power tool 2.
The energy storage cells 23 may also be referred to as rechargeable battery cells and serve for taking up, storing and providing electrical energy or an electrical voltage.
The rechargeable battery interface 22 is positioned on one side of the housing 21. The rechargeable battery interface 22 comprises a number of power connectors for taking up and delivering electric current and also data connectors for transmitting and receiving signals between the power tool 2 and the rechargeable battery 3. The electric current from the energy storage cells 23 can be delivered by way of the power connectors.
As shown in
Through the connection, electric current can flow from the energy storage cells 23 of the rechargeable battery 3 to the power tool 2. Furthermore, signals can be exchanged for communication between the rechargeable battery 3 and the power tool 2.
As can be seen from
In order to transmit a signal corresponding to the travel of the activation switch 13 in direction A to the controller 9, the activation switch 13 comprises a potentiometer (not shown).
If the activation switch 13 moves again in direction B, a corresponding signal is transmitted to the controller 9 with the aid of the potentiometer (not shown), with the result that electric current no longer flows from the rechargeable battery 3 to the power tool 2.
During the delivery of electrical energy, the energy storage cells 23 heat up. The temperature profile of the rechargeable battery cells (see
In the event that the temperature of the rechargeable battery cells rises above 70° C. and the voltage of a rechargeable battery cell falls below 2.5 volts, the control electronics 24 of the rechargeable battery 3 stop the delivery of electrical energy to the power tool 2.
In order to prevent the delivery of electrical energy from the rechargeable battery to the power tool being ended due to a critical temperature threshold value of the rechargeable battery cells 23 being reached too early, the power of the power tool is reduced accordingly. For this purpose, the speed of the drive 8 is reduced with the aid of the control device 9. By reducing the speed of the drive 9, the value of the current intensity that flows from the rechargeable battery cells 23 to the drive 8 of the power tool is reduced. Due to the lower intensity of the current, the temperature rise at the rechargeable battery cells slows down, so that electrical voltage (i.e. electrical energy) can be drawn from the rechargeable battery cells for a longer period of time.
Furthermore, the value of the current intensity with which the slowest possible rise in temperature in the rechargeable battery cells 23 is achieved is stored in the memory device 28 of the rechargeable battery 3. When the rechargeable battery 3 is fully charged to be used again as a power supply for a power tool 2, the value of the current intensity with which the slowest possible temperature rise in the rechargeable battery cells 23 is achieved is sent to the control device 9 of the power tool 2. With the help of this determined current intensity value, the power output of the drive 8 can be set or selected right at the beginning of the use of the charged battery 3 in such a way that the temperature at the rechargeable battery cells 23 is prevented from increasing too quickly and the rechargeable battery cells 23 are discharged almost completely.
Number | Date | Country | Kind |
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19200696.3 | Oct 2019 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/076383 | 9/22/2020 | WO |