Electric Processing Tool Having an Energy Supply Device

Abstract

An electric processing tool includes an energy supply device and an open-loop or closed-loop control unit. The energy supply device includes at least two energy sources which are interconnected, each in a series circuit with an electronic component for applying the logical operator “OR” to the individual current of the electronic component in question, to form a common star point, such that a resulting total current for supplying the electric processing tool results. At least a subset of the energy sources, in particular each energy source, is assigned a current-measuring unit for measuring the individual current of the energy source in question. The open-loop or closed-loop control unit is configured to adapt the total current to the measured individual currents.

Claims

1. An electric processing tool comprising: an energy supply device; a current measurement unit; and an open-loop or closed-loop control unit, wherein the energy supply device comprises has at least two energy sources, which are each interconnected in a series circuit with an electronic component configured to apply a logical operator “OR” to individual currents from the at least two energy sources so as to form a common star point in such a way that a resultant summation current results for supplying power to the electric processing tool, wherein the current measurement unit is configured to measure the individual currents from the at least two energy sources, and wherein the open-loop or closed-loop control unit is configured to match the summation current to the measured individual currents.

2. The electric processing tool as claimed in claim 1, wherein the energy supply device further comprises, at least for a subset of the at least two energy sources, a voltmeter configured to measure a voltage provided by a respective energy source included in the subset of the at least two energy sources.

3. The electric processing tool as claimed in claim 1, wherein the energy supply device further comprises a voltmeter configured to measure a supply voltage at the star point.

4. The electric processing tool as claimed in claim 1, wherein the energy supply device further comprises a current measurement unit configured to measure the summation current at the star point.

5. The electric processing tool as claimed in claim 1, wherein the energy supply device further comprises a temperature measurement device configured to measure a temperature.

6. The electric processing tool as claimed in claim 1, wherein the energy supply device further comprises at least one protective circuit configured to protect from an overvoltage.

7. The electric processing tool as claimed in claim 1, wherein the energy supply device further comprises at least one protective circuit configured to protect from an overcurrent.

Description

EXEMPLARY EMBODIMENTS

Drawings

[0017] The invention will be explained by way of example below with reference to FIGS. 1 to 3, wherein identical reference symbols in the figures indicate identical parts having an identical function.

[0018] In the drawings:

[0019] FIG. 1 shows a block circuit diagram of a first exemplary embodiment of an energy supply device according to the invention for an electric processing tool,

[0020] FIG. 2 shows a block circuit diagram of a second exemplary embodiment of the energy supply device according to the invention for an electric processing tool, and

[0021] FIG. 3 shows a block circuit diagram of a third exemplary embodiment of the energy supply device according to the invention for an electric processing tool.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0022] FIG. 1 shows a block circuit diagram of a first exemplary embodiment of an energy supply device 10 according to the invention of an electric processing tool (not illustrated in any more detail). As has already been described at the outset, in the context of the invention, an electric processing tool should be understood to mean, for example, an electric tool for processing workpieces by means of an electrically driven tool insert. In this case, the electric tool can be in the form of both an electric hand tool operated by a rechargeable battery and a stationary electric machine tool, which is supplied power by means of interchangeable rechargeable battery packs and possibly additionally by means of line current. Typical electric tools are in this connection handheld drills or drill presses, screwdrivers, hammer drills, rotary hammer drills, planes, angle grinders, sanders, polishing machines, circular saws, table saws, miter saws and jigsaws or the like. However, possible electric processing tools are also gardening tools such as lawnmowers, lawn trimmers, pruning saws or the like. Furthermore, the invention can also be applied to domestic appliances such as vacuum cleaners, mixers, etc.

[0023] The energy supply device 10 is in the form of a power ORing system having a first energy source 12 and a second energy source 14. The two energy sources 12 and 14 can be in the form of interchangeable rechargeable battery packs or interchangeable rechargeable batteries 16 of the electric processing tool. It is likewise conceivable that the first energy source 12 is an interchangeable rechargeable battery pack 16 and the second energy source 14 is the power pack of a grid power supply. Depending on the power class of the electric processing tool, very different interchangeable rechargeable battery packs or interchangeable rechargeable batteries 16 and energy sources 12, 14 can be used. Since the configuration of such interchangeable rechargeable battery packs or interchangeable rechargeable batteries 16 and energy sources 12, 14 is known to a person skilled in the art, no further details will be set forth in this regard below. Also, the number of energy sources can vary. The invention is therefore not restricted to two energy sources 12, 14.

[0024] The two energy sources 12, 14 are each interconnected in series with an electronic component 18 for ORing their individual currents I.sub.1 and I.sub.2 so as to form a common star point 20. The electronic components 18 can be in the form of diodes 22, for example, whose cathodes are at the same potential at the star point 20. The diodes 22 can be in the form of Schottky diodes, for example, which have a relatively high leakage current of up to approximately 100 mA in the reverse direction. However, in principle other types of diodes are also conceivable which are suitable for ORing the individual currents. Instead of the diodes 22, however, it is also conceivable to use MOSFETs having an “Ideal Diode Controller” IC, such as, for example, an LTC4357, ZXGD3112N7, LM5051 or the like.

[0025] The power ORing of the first energy source 12 with its individual current I.sub.1 and the second energy source 14 with its individual current I.sub.2 results in a resultant summation current I.sub.S downstream of the star point 20 in the direction of current flow for supplying power to the electric processing tool or to a consumer 24 contained therein which may be, for example, in the form of an electric motor and/or an open-loop or closed-loop control loop for the electric motor. Virtually anything which significantly influences the power requirement of the electric processing tool is possible as the consumer 24 of the electric processing tool.

[0026] In accordance with the invention, provision is made for a current measurement unit 26 for measuring the individual currents I.sub.1, I.sub.2 of the energy sources 12, 14 to be assigned to each energy source 12, 14. The current measurement unit 26 can be in the form of, for example, a shunt resistor 28, which is connected in series with the energy source 12, 14 and the electronic component 18 for ORing the individual currents I.sub.1, I.sub.2. However, a Hall sensor or the like is also conceivable for the current measurement. The current measurement units 26 are connected to an open-loop or closed-loop control unit 30 of the energy supply device 10. The open-loop or closed-loop control unit 30 matches the summation current I.sub.S to the measured individual currents I.sub.1, I.sub.2 in such a way that the energy sources 12, 14 can always be operated in their respectively permissible operating range.

[0027] The information on the maximum permissible summation current I.sub.S is provided to the consumer 24 by the open-loop or closed-loop control unit 30, for example, via a bus system, an analog voltage signal, a frequency-modulated signal or the like. The consumer 24 of the electric processing tool can then adapt the power consumption in such a way that, limited by the internal resistances and supply voltages of the individual energy sources 12, 14, in each case one individual current I.sub.1, I.sub.2 can be drawn from the energy sources 12, 14 which is within the respectively permitted operating range.

[0028] In addition it is conceivable for a plurality of components of the power ORing to be interconnected in series in such a way that, in the event of failure of one component, a current flow into one of the energy sources 12, 14 is suppressed.

[0029] FIG. 2 shows a block circuit diagram of a second exemplary embodiment of the energy supply device 10 according to the invention. The components provided with the same reference symbols are identical to those according to FIG. 1 and will therefore not be explained again here. The substantial difference with respect to the first exemplary embodiment is a current measurement unit 32 for measuring the summation current I.sub.S at the star point 20. Similarly to the current measurement units 26, the current measurement unit 32 can also be in the form of a shunt resistor 28 or another component suitable for current measurement. The current measurement unit 32 is connected to the open-loop or closed-loop control unit 30 so that a plausibility check in respect of the measured individual currents I.sub.1, I.sub.2 of the energy sources 12, 14 is possible by means of the measured summation current I.sub.S. In addition to the currents, in the second exemplary embodiment in addition also the individual voltages U.sub.1, U.sub.2 of the two energy sources 12, 14 and the supply voltage Us are detected at the star point by the open-loop and closed-loop control unit 30. These can also be used for a plausibility check in respect of the measured individual currents I.sub.1, I.sub.2.

[0030] FIG. 3 shows a block circuit diagram of a third exemplary embodiment of the energy supply device 10 according to the invention. The individual components substantially correspond to those from FIGS. 1 and 2, wherein now, however, for reasons of improved clarity, the parallel-operated energy sources 12, 14 and 34 are illustrated one below the other. In this case, 34 denotes an n-th energy source, which in this case is additionally in the form of a power pack (AC/DC conversion) of a grid power supply.

[0031] All of the n energy sources 12, 14, 34 are interconnected in parallel in the sense of power ORing by means of, for example, electronic components 18 in the form of diodes 22 for ORing the individual currents I.sub.1, I.sub.2, . . . I.sub.n at the star point 20, with the result that the individual currents I.sub.1, I.sub.2, . . . I.sub.n of the n energy sources 12, 14, 34 downstream of the star point 20 result in the summation current I.sub.S for supplying power to the electric processing tool 12 or a consumer 24 contained therein. In this case, the consumer 24 of the electric processing tool 12 can also be divided into a plurality of individual consumers 24a, 24b which are dependent on one another or independent of one another. For example, it is conceivable that the consumers 24a, 24b are a plurality of electric motors for driving a cutting bar and a gear train (separate therefrom) of a lawnmower.

[0032] Similarly to FIG. 2, the open-loop or closed-loop control unit 30 receives information on the measured individual currents I.sub.1, I.sub.2, . . . I.sub.n of the n energy sources 12, 14, 34 and the summation current I.sub.S at the star point 20 by means of the current measurement units 26 and 32. The latter can be in the form of shunt resistors 28 or other components suitable for current measurement. In addition to the current measurement units 26 and 32, the open-loop or closed-loop control unit 30 also receives specific data D from the energy sources 12, 14, 34, such as, for example, their type, their permissible operating range, temperature measured values, etc. These can be used in addition for matching the summation current I.sub.S.

[0033] Furthermore, 36 and 38 denote means for detecting the individual voltages U.sub.n of the energy sources 12, 14, 34 and the supply voltage U.sub.S at the star point 20. The means 36, can additionally also be in the form of overvoltage protection 40 for protection from voltage peaks, such as can arise, for example, when an energy source 12, 14, 34 in the form of an interchangeable rechargeable battery pack 16 is removed during running operation of the electric processing tool. In this case, in particular TVS diodes, capacitors or other means suitable for protection from overvoltages can be used. In addition or as an alternative, the means 36, 38 can also have the function of overcurrent protection 42. Such protective circuits can be realized, for example, by fuses, MOSFETs or correspondingly suitable means for interrupting the respective current paths.

[0034] Furthermore, the energy supply device 10 has a temperature measurement device 44 for measuring a temperature T. On the basis of the measured temperature T, the open-loop or closed-loop control unit 30 can, if required, limit the summation current I.sub.S in such a way that firstly the energy sources 12, 14, 34 remain in their permitted operating range and secondly the thermal limits of the energy supply device 10 are maintained. This is particularly expedient when the energy sources 12, 14, 34 themselves cannot transmit individual temperature values to the open-loop or closed-loop control unit 30 by means of the data D.

[0035] Finally, reference will be made to the fact that the invention is not restricted to the exemplary embodiments shown in the three figures. Thus it is conceivable for only a subset of energy sources, instead of all of them, to be equipped with an ammeter and/or a voltmeter. This can be expedient, for example, in the case of an electric processing tool which is supplied power via two interchangeable rechargeable battery packs 16 and in which the individual current of one of the two interchangeable rechargeable battery packs can be calculated in accordance with Kirchhoff's laws using the summation current at the star point and the measured individual current of the other interchangeable rechargeable battery pack 16.