Handheld electrical machine tool with shut-off delay apparatus

0001The present invention relates to at least one electrical drive mechanism and at least one electrical device that requires electrical energy for its function and the electrical drive mechanism and / or a cutoff delay device for the electrical device and the electrical drive mechanism and the subject. It relates to a handheld power tool provided with at least one rechargeable battery for powering an electrical device.

0002Conventional technology Such handheld power tools are known. Here, when the handheld power tool is shut off, for example by depressing a corresponding key switch (Tasterdruecker), the rechargeable battery is completely disconnected from all electrical loads on the handheld power tool. This is usually done without time delay in the electric drive mechanism of handheld power tools. This is because the post-operation or extension operation of the tool driven by the electric drive mechanism is not desirable. However, in other electrical devices, the cutoff delay is significant. The electrical device here is, for example, an additional measuring device, an inspection device, or a control electronic circuit itself. While electrical components with high current consumption are usually cut off without delay, it is advantageous for electrical devices such as control electronics that consume very little current to be cut off after delay. Since it takes some time for the control electronic circuit to be completely ready for operation, if the handheld power tool is reswitched on from the state where the control electronic circuit is cut off, there is some time from the user's request for switching to the response. Wasted time occurs. This is not user-friendly and can cause malfunctions, especially with manually operated tools. This is because it takes longer than the user expects to activate the electric drive mechanism. By delaying the interruption of the control electronic circuit at the time of reuse within such a delay time, it is possible to avoid the occurrence of wasted time. However, even in an electric device that requires almost no electric energy to operate, a battery-powered handheld power tool causes battery discharge. When the battery reaches the consumable discharge area, the battery is damaged.

0003Issues on the basis of the present invention An object on which the present invention is based is to prevent the rechargeable battery from being consumed and discharged even when the interruption of at least one electric device is delayed.

0004Means to solve problems This problem is solved by providing a consumable discharge protection device that sets the delay time of the cutoff delay device based on the detected charge level of the rechargeable battery.

0005According to such a consumable discharge protection device, the extraction time of electric energy by the rechargeable battery is limited by the charge level of the rechargeable battery itself. Therefore, further discharge from the rechargeable battery to the electrical device is only performed within a predetermined range based on the charge level of the rechargeable battery.

0006Advantageous embodiment According to one embodiment of the present invention, the cutoff delay device has a consumable discharge protection device. In this way, the number of required elements can be reduced.

0007In particular, the consumable discharge protection device sets the delay time of the cutoff delay device short when the charge level is small. As the charge level decreases, the energy that can be extracted from the battery is set smaller, reducing the risk of reaching a consumable discharge region that is an obstacle to the battery.

0008Further, the cutoff delay device does not perform cutoff delay when the charge level falls below a predetermined charge limit value. That is, when the charge level drops below a predetermined charge limit, the electrical device is shut off without time delay. By this means, further discharge of the battery is prevented.

0009Further, the present invention comprises at least one electric drive mechanism, at least one electric device that requires electrical energy to function, a cutoff delay device for the electric drive mechanism and / or the electric device, and the electricity. It relates to a method of driving a handheld power tool provided with a drive mechanism and at least one rechargeable battery for powering the electrical device. According to the present invention, the charge level of the rechargeable battery is detected by the consumable discharge protection device, the delay time of the cutoff delay device is set based on the detected charge level, and the electric device is affected by the cutoff delay device. It is delayed by the delay time and blocked. With such a driving method, the extraction time of electric energy by the rechargeable battery is limited by the charge level of the rechargeable battery itself.

0010According to another advantageous embodiment of the present invention, the consumable discharge protection device sets the delay time of the cutoff delay device short when the charge level is low. The short delay time reduces the time it takes for the electrical device to extract electrical energy from the battery and reduces the amount of battery discharge.

0011Further, the cutoff delay device shuts off the electric device without a time delay when the charge level falls below a predetermined charge limit value. In this case, the consumable discharge protection device may set the delay time to 0 s, or the cutoff delay device may cut off without delay.

0012Particularly advantageous, the delay time is adopted only by the set value. The value of the delay time can be, for example, an integral multiple of the set time.

0013According to another advantageous embodiment of the present invention, the consumable discharge protection device is set so that the delay time continuously changes until the charge level reaches the charge limit value. By continuously changing the set value of the delay time, the cutoff delay device can continuously adjust the cutoff delay to the charge level.

0014Alternatively, the consumable discharge protection device may be set so that the delay time changes stepwise with the charge level.

0015According to another advantageous embodiment of the present invention, the charge level is determined by determining the battery voltage of the rechargeable battery by the consumable discharge protection device. The battery voltage changes with the charge level upon full or partial discharge of the battery. The battery voltage uniquely infers the battery charge level in the load region. When the battery is based on a lithium-ion cell, the battery voltage drops sharply as the charge level drops. As this type of battery continues to discharge, a sharp drop in battery voltage must be monitored, even with low current consumption by the electrical device.

0016According to another advantageous embodiment of the present invention, the battery voltage is measured with a corresponding current under a predetermined electrical load. When the battery voltage is obtained continuously or at predetermined intervals during driving, the battery voltage is loaded by an electric load such as an electric drive mechanism. In order to infer the charge level of the battery, the battery voltage must be measured with a reasonable current. If the characteristic curve of the battery is known from the measurement, the no-load voltage or charge level of the battery can be inferred.

0017Alternatively or additionally, the battery voltage can be measured in a nearly non-current state. For example, when the battery voltage is measured after shutting off the electric drive mechanism and all the elements having high current consumption, the no-load voltage of the battery is measured in a pseudo-no-current manner.

0018According to another advantageous embodiment of the present invention, the consumable discharge protector allows the electric drive mechanism to be switched on only when the charge level exceeds the electric drive mechanism switch-on threshold. Therefore, the electric drive mechanism switch-on threshold is selected so that the charge level of the battery can guarantee the drive of the handheld power tool for a predetermined time corresponding to the application state.

0019In addition, the consumable discharge protection device allows the electrical device to be switched on only when the charge level exceeds the electrical device switch-on threshold. This means prevents further discharge of the battery due to reswitching on of the electrical device. Since the electric load of the electric device is smaller than the electric load of the electric drive mechanism, the electric device switch-on threshold is much smaller than the electric drive mechanism switch-on threshold.

0020A brief description of the drawing Hereinafter, the present invention will be described in detail with reference to the illustrated examples.

0021FIG. 1 shows a schematic view of a handheld power tool equipped with a cutoff delay device. Figure 2 shows a graph showing the relationship between delay time and battery voltage.

0022FIG. 1 shows the basic structure of a handheld power tool 1 driven by a rechargeable battery. FIG. 1 shows only the parts that are important for turning on / off the power tool 1. The operation unit 2 is connected to a cutoff delay device 3, and the cutoff delay device 3 acts on the electric drive mechanism 6 and the electric device 7 of the power tool 1 via the switching devices 4 and 5. The switching device 4 is assigned to the electric drive mechanism 6, and the switching device 5 is assigned to the electric device 7. Further, the power tool 1 has a consumable discharge protection device 8 which is a part of the cutoff delay device 3 in this embodiment. The parts of the power tool 1, particularly the electric drive mechanism 6 and the electric device 7, are powered by the rechargeable battery 9. However, the corresponding power supply line is not shown. The electric device 7 is, for example, the control electronic circuit 10 of the power tool 1. The operation unit 2 is configured as, for example, a push button of the key switch 11. The switching devices 4 and 5 can also be a part of the cutoff delay device 3. Instead of this, one of the switching devices 4 and 5 may be directly connected to the operation unit 2. In the switching device 4 assigned to the electric drive mechanism 6, it is often necessary to guarantee that the electric drive mechanism and thus the power tool are stopped with as little delay as possible.

0023The power tool 1 provided with the cutoff delay device 3 performs the following functions. That is, when the user operates the operation unit 2 to shut off the power tool 1, the power tool 1 is shut off from the operation unit 2 to the cutoff delay device 3 at the cutoff time t.₀Is set. A calculator (not shown) determines the charge level of the rechargeable battery 9 and supplies the corresponding signal to the consumable discharge protection device 8. The consumable discharge protection device 8 sets the delay time Δt for the interruption delay of the electric device 7 based on the charge level of the rechargeable battery 9. In this embodiment, the delay time Δt is not set for the interruption of the electric drive mechanism 6, and the interruption delay device 3 sets the electric drive mechanism 6 at the time point t.₀Shut off with. Shutdown here means completely disconnecting the electrical load (here, the electrical drive mechanism 6) from the rechargeable battery 9. When shutting off the electric device 7, the cutoff delay device 3 considers the delay time Δt set by the consumable discharge protection device 8 and sets the electric device 7 to the time point t.₀Block at + Δt. That is, after the operation of the operation unit 2, the electric drive mechanism 6 is cut off without delay, and the electric device 7 is cut off with a delay time Δt. The detection of the charge level of the rechargeable battery 9 is performed by obtaining the battery voltage U in this embodiment, and the battery voltage is also used as an input value of the consumable discharge protection device 8.

0024In the graph of Fig. 2, the vertical axis is the delay time Δt and the horizontal axis is the relative battery voltage U / U._maxIt is shown. U_maxA value of 100% corresponds to the maximum battery voltage of a fully charged battery 9. Battery voltage U is a measure of the charge level of battery 9. The consumable discharge protection device 8 defines a plurality of relationships between the battery voltage U and the delay time Δt for various application fields, and these are shown as a graph in FIG. In the graph, a plurality of qualitative relationships between the delay time Δt set by the consumable discharge protection device 8 and the battery voltage U are shown as characteristic curves 12 to 16. Each voltage threshold U_sCorresponds to the charge limit value when the delay time Δt drops to zero, for example the maximum value U_maxIt is shown in the area of about 15% to about 50% of. Voltage threshold U_sIs selected lower in the graph of Fig. 2, and the shape of the characteristic curve is the voltage threshold U._sIt can be seen above. Voltage threshold U currently used_sIs a higher value than shown in the graph in Figure 2. Characteristic curve 12 ~ 16 and maximum value U_maxIntersection with the straight line Δt_mThe magnitude of is the maximum delay time of each characteristic curve 12-16. Each voltage threshold U_sFor smaller battery voltage values, characteristic curves 12-16 have a constant delay time Δt = 0. Battery voltage U is the corresponding voltage threshold U_sBelow, the electrical device 7 is shut off without delay in all characteristic curves. Therefore, in the following, each voltage threshold value U in each characteristic curve 12 to 16_sConsider only the areas above.

0025The stepped characteristic curve 12 shows a dramatic change in the delay time Δt as the battery voltage U changes, and each voltage region corresponds to a fixed delay time value. The characteristic curve 13 shows the relative battery voltage U / U._maxIt shows how the delay time Δt changes continuously throughout. The characteristic curve 14 is the maximum value U._maxMaximum delay time Δt in the region of 100% to 65% of_mTake a constant delay time Δt corresponding to, and the maximum value U_maxIn the region of 65% to 20% of, it linearly decreases to Δt = 0 with the battery voltage U, and this value is the threshold value U._sIt becomes the point of. The characteristic curve 15 is shown by a broken line, and has a constant delay time Δt in the region of 100% to 50%, and drops sharply to Δt = 0 at 50%. The characteristic curve 16 shows the maximum delay time Δt in the region of 100% to 65%._mIt has a constant delay time Δt corresponding to, and decreases linearly with the battery voltage U in the range of 65% to 40%, and sharply decreases to Δt = 0 at 40%.

0026In addition to setting the delay time Δt for the cutoff delay device, the consumable discharge protection device 8 may set a switch-on threshold for the reswitch-on of individual parts of the power tool 1, such as the electric drive mechanism 6 and the electric device 7. it can. Here, the above-mentioned charge threshold value, that is, the charge limit value, the switch-on threshold value, or the voltage threshold value corresponding thereto does not necessarily have to be fixed, and is based on at least one limit condition, for example, the temperature measured directly around the battery. It is adjustable.

0027<figref num="1">It is the schematic of the handheld type power tool.</figref><figref num="2">It is a graph which shows the relationship between the delay time and the battery voltage.</figref>