System having a handheld power tool and a battery unit

Abstract

A battery-operated handheld power tool (1) is provided, comprising a receiving compartment (4) for releasably receiving at least one battery unit (10, 20, 30). The receiving compartment (4) comprises at least four electrical contacts (K1-K4) for making contact with at least four corresponding contacts of the at least one battery unit (10, 20, 30), wherein a load of the handheld power tool (1) is connected between a first contact (K1) and a fourth contact (K4), wherein a switch (3) capable of switching between an open switch state and a closed switch state is connected between a second contact (K2) and a third contact (K3), and wherein, via the switch (3), a first cell arrangement (31) and a second cell arrangement (32) of the battery units (10, 20, 30) are connected in series or a first battery unit (10) and a second battery unit (20) are connected in series.

Description

Technical Field

[0001] The invention relates to a battery-operated handheld power tool, a battery unit for a handheld power tool, a system comprising a handheld power tool and a battery unit, a charging device for a battery unit, and a system comprising a battery unit and a charging device. Background Art

[0002] Battery units for handheld power tools typically have multiple cells connected in series to increase the battery unit's output voltage. For example, a battery unit with ten lithium-ion cells and an output voltage of approximately 36 V is known. A higher output voltage can be advantageous because lower current flows for the same electrical power. This allows, for example, for smaller line cross-sections and the use of components designed for lower currents. Furthermore, battery cell aging can be reduced because the lower discharge current places less stress on the battery cell.

[0003] However, higher voltages are associated with a higher risk of injury. Various protective regulations exist, which stipulate, for example, that electrical contacts may no longer be exposed if a certain maximum voltage is exceeded. This then requires a correspondingly higher level of design effort and makes the corresponding devices more complex and expensive.

[0004] Against this background, it is an object of the present invention to provide an improved handheld power tool, an improved battery unit and / or an improved charging device. Summary of the Invention

[0005] A first aspect provides a battery-operated handheld power tool having a receiving compartment for releasably receiving at least one battery cell. The receiving compartment has at least four electrical contacts for contacting four corresponding contacts of the at least one battery cell, wherein a load of the handheld power tool is connected between a first contact and a fourth contact, wherein a switch capable of switching between an open switch state and a closed switch state is connected between the second contact and the third contact, and wherein the first cell arrangement of the battery cell is connected in series with the second cell arrangement, or the first battery cell is connected in series with the second battery cell, via the switch.

[0006] The handheld power tool has the advantage that it can be operated during operation at a high voltage, which can be, for example, above the protective undervoltage (DC) of 60 V or another threshold, without having to protect the contacts of the battery cells by special measures. The use of a plurality of individual battery cells has the advantage that the battery cells are not electrically connected to one another in the unloaded state when they are inserted into the handheld power tool, which reduces the risk of short circuits, etc.

[0007] Handheld power tools, in particular, are in the form of drills, impact drills, hammer drills, handheld circular saws, jigsaws, foxtail saws, angle grinders, blenders, etc.

[0008] In particular, the handheld power tool can be configured to accommodate more than one battery cell, particularly to achieve an increased operating voltage for the handheld power tool. However, the handheld power tool can also be operated with only one battery cell, which provides the necessary operating voltage via the corresponding cell arrangement. Accordingly, the handheld power tool can be operated with one, two, or more than two battery cells. It should be noted that the "necessary operating voltage" refers to the design voltage of the handheld power tool. Therefore, this does not exclude the possibility that the handheld power tool can also be operated with different voltages.

[0009] At least four electrical contacts are required to enable a switchable series connection of the battery cells or cell arrangements, which is controlled by a control device of the handheld power tool. A distinction can be made between two applications.

[0010] First, a single battery cell can be configured to provide the necessary operating voltage. This cell internally has two battery cells that are not electrically connected to each other. Instead, each cell can be contacted via two externally connected contacts. When the switch is closed, the two cells are connected in series via each contact, thus completing the circuit and providing a voltage corresponding to the sum of the voltages of the two cells across the two remaining contacts.

[0011] Second, two (or more) battery cells can be used, each with a voltage lower than the necessary operating voltage of the handheld power tool. When the battery cells are inserted, they remain electrically disconnected from each other until the user activates a main switch, a torque controller, or the like. Closing the switch closes the circuit through the two battery cells, allowing current to flow.

[0012] In both cases, the risk from the handheld power tool is reduced, since a predetermined threshold value, for example an upper limit value, for the voltage present in the no-load state can be adhered to in a particularly simple manner.

[0013] When the handheld power tool is operated, the current for driving the motor of the handheld power tool is particularly conducted via the switch. Therefore, the switch also serves as a device for improving safety because it can be used to interrupt the power supply to the motor.

[0014] According to an embodiment of the battery-operated handheld power tool, the switch is a switch which is manually operable by a user of the handheld power tool.

[0015] According to another embodiment of the battery-operated handheld power tool, the switch includes a semiconductor device that can be changed to an open switch state or a closed switch state by a specific control signal.

[0016] According to another embodiment of the battery-operated handheld power tool, the control device of the handheld power tool is configured to output a specific control signal upon actuation of a main switch of the handheld power tool.

[0017] According to another embodiment of the battery-operated handheld power tool, the switch includes two MOSFETs connected in series with opposite polarities.

[0018] When using MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), this arrangement is advantageous for the body diode, which can break down. The two MOSFETs are switched via specific control signals.

[0019] Instead of MOSFETs, other types of transistors can also be used, such as IGBTs with freewheeling diodes.

[0020] According to another embodiment of the battery-operated handheld power tool, the switch comprises four MOSFETs arranged in two pairs connected in parallel with each other, wherein the two MOSFETs of each pair are connected in series with opposite polarities.

[0021] This arrangement is advantageous, on the one hand, in order to have redundancy with respect to MOSFET failures, and on the other hand, the current carrying capacity of the arrangement is increased and the thermal load on the individual MOSFETs is reduced.All four MOSFETs are preferably switched via a specific control signal.

[0022] A second aspect provides a battery unit for a handheld power tool, wherein the battery unit has a plurality of battery cells and a plurality of contacts extending to the outside in pairs, wherein respective pairs of the plurality of contacts can be connected to electrodes of associated battery cells in the plurality of battery cells.

[0023] The battery unit may advantageously be used to operate the handheld power tool according to the first aspect.

[0024] Passive or active electronic components (eg diodes etc.) can be arranged between the external contacts and the electrodes of the corresponding cell arrangement.

[0025] According to an embodiment of the battery unit, each of the plurality of cell arrangements has a maximum output voltage lower than 60V.

[0026] This means that the output voltage is below the upper limit of the protective low voltage, which is why no special safety measures are required to protect the contacts.

[0027] According to one embodiment of the battery unit, each of the plurality of cell arrangements includes a plurality of lithium-ion cells.

[0028] According to another embodiment of the battery unit, each cell arrangement of the plurality of cell arrangements has a maximum of 14 lithium-ion cells connected in series.

[0029] This embodiment has the advantage that the charging voltage required for charging the corresponding cell arrangement is below a value of 60 V (direct current). The charging voltage for a single lithium-ion cell is 4.2 V, for example.

[0030] According to a further embodiment of the battery cell, the battery cell has exactly two cell arrangements and four contacts leading to the outside.

[0031] According to a further embodiment of the battery cell, the battery cell has exactly three cell arrangements and six contacts leading to the outside.

[0032] A third aspect proposes a system having a battery-operated handheld power tool according to the first aspect and a battery unit according to the second aspect.

[0033] The embodiments and features described with respect to the handheld power tool and the battery unit apply accordingly to the system, and vice versa.

[0034] A fourth aspect provides a charging device for charging the battery unit according to the second aspect, wherein the charging device is configured to charge each cell device of the battery unit individually.

[0035] Specifically, the charging device includes a receiving compartment for receiving a battery cell and a plurality of paired contacts corresponding to the battery cells for making contact with the contacts of the battery cells. The battery cell devices that can be connected to the contact pairs are charged via the corresponding contact pairs. In this case, each battery cell device is charged separately from the other battery cell devices. To this end, the charging device can have corresponding multiple charging circuits to provide charging voltage and charging current. Alternatively, it can be proposed that the charging device has only one charging circuit, via which the battery cell devices are charged sequentially in time.

[0036] If the battery unit has, for example, two cells and four contacts, the charging device accordingly has four contacts and one or two charging circuits. If the battery unit has, for example, three cells and six contacts, the charging device accordingly has six contacts and up to three charging circuits.

[0037] A fifth aspect provides a system having the battery unit according to the second aspect and the charging device according to the fourth aspect.

[0038] The embodiments and features described for the battery unit and the charging device apply correspondingly to the system, and vice versa.

[0039] It is particularly advantageous if the battery unit has a plurality of cell arrangements with lithium-ion cells, wherein each cell arrangement comprises a maximum of 14 lithium-ion cells connected in series.

[0040] This embodiment has the advantage that the charging voltage required to charge the corresponding cell arrangement is below a value of 60 V (DC). The charging voltage for a single lithium-ion cell is, for example, 4.2 V. Consequently, no special safety precautions, such as covering the contacts, are necessary for the charging device. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The following description explains the invention with reference to exemplary embodiments and the accompanying drawings, in which:

[0042] Figure 1 shows a schematic diagram of a battery-operated handheld power tool;

[0043] Figure 2 shows a schematic circuit arrangement;

[0044] Figure 3 A schematic diagram showing a battery cell; and

[0045] Figure 4 A schematic diagram of a charging device for a battery cell is shown.

[0046] Unless otherwise stated, identical or functionally identical elements are denoted by the same reference numerals in the figures. DETAILED DESCRIPTION

[0047] Figure 1 A schematic diagram of a battery-operated handheld power tool 1, in this case in the form of a hammer drill, is shown. The handheld power tool 1 has a receiving compartment 4, which in this example has four contacts K1-K4. The receiving compartment 4 is configured to receive two battery cells 10, 20 or one battery cell 30. In each case, the four contacts K1-K4 of the receiving compartment 4 make contact with four corresponding contacts K1'-K4' of the battery cell 30 or with two corresponding pairs of contacts of each battery cell 10, 20.

[0048] The load of the handheld power tool 1, specifically an electric motor (not referenced), is connected between the first contact K1 and the fourth contact K4 of the receiving compartment 4. In the illustrated example, contacts K1 and K4 are connected to a control device 2, which switches the drive current of the electric motor. A switch 3, which can be switched between an open and closed state, is connected between the second contact K2 and the third contact K3. Via switch 3, the first and second battery cell arrangements 31 and 32 of the battery cells, or the first and second battery cells 10 and 20, are connected in series. By connecting the battery cells 31 and 32 or the battery cells 10 and 20 in series, the output voltages of the battery cells 31 and 32 or the battery cells 10 and 20 are added together. Accordingly, the increased voltage can be tapped between the first contact K1 and the fourth contact K4.

[0049] When switch 3 is open, Figure 1 As shown, the circuit is interrupted and no current can flow. This does not exclude current from being drawn from at least one battery cell 10, 20, 30 (eg, between the first contact K1 and the second contact K2). However, correspondingly only a lower voltage is present.

[0050] The control device 2 is configured to output a specific control signal SIG for controlling the switch 3. In this example, the control device 2 controls the switch 3 to close when, for example, the main switch 5 of the handheld power tool 1 is actuated.

[0051] Figure 1 The dashed box in FIG. 1 is used to indicate a system 100 , which includes a battery-operated handheld power tool 1 and a battery unit 30 having a plurality of battery cell devices 31 , 32 .

[0052] Figure 2 It shows that it can be used for example Figure 1 Schematic circuit layout of a switch 3 of a handheld power tool 1. Switch 3 includes four semiconductor elements 3A, 3B, 3C, and 3D in the form of MOSFETs. The four MOSFETs 3A, 3B, 3C, and 3D are arranged in two pairs, P1 and P2. These two pairs, P1 and P2, are electrically connected in parallel. In each pair, P1 and P2, the MOSFETs 3A, 3B, 3C, and 3D are connected in their forward directions in opposite directions. Therefore, in order for current to flow through one of the two branches, both MOSFETs in the corresponding branch must be turned on.

[0053] All four MOSFETs 3A, 3B, 3C, 3D are advantageously controlled by the same specific control signal SIG ( Figure 1) so that they are all turned on or off simultaneously. In the illustrated arrangement, the current flowing through the corresponding MOSFETs 3A, 3B, 3C, 3D is halved compared to an arrangement with only two MOSFETs 3A, 3B or 3C, 3D (e.g., only P1 or P2). This makes switch 3 more robust and reliable overall.

[0054] Figure 3 A schematic diagram of a battery cell 30 is shown. The battery cell 30 may be used, for example, to operate Figure 1 The handheld power tool 1 in FIG. A battery unit 30 includes two cell arrangements 31 and 32 . Each cell arrangement 31 and 32 includes a plurality of individual cells 33 connected in series, as shown by way of example on cell arrangement 32 . These cells are, for example, lithium-ion cells 33 , each providing a maximum output voltage of 3.6 V (when fully charged). When connected in series, the fourteen cells 33 thus achieve a maximum output voltage of 50.4 V.

[0055] The battery unit 30 has four contacts K1'-K4' leading to the outside. In each case, two of these contacts K1'-K4' are connected to the electrodes of the associated cell arrangement 31, 32. This means that, for example, a maximum output voltage of 50.4 V can be provided at the contacts K3' and K4'. When the two cell arrangements 31, 32 are operated as in reference Figure 1 The handheld power tool 1 is described during use of the switch 3 (see Figure 1 or 2) when connected in series, thus providing a maximum output voltage of 100.8 V.

[0056] It should be noted that the battery unit 30 may also have more than two cell arrangements 31, 32, and that the respective cell arrangements 31, 32 may have more or fewer than fourteen series-connected cells 33. In particular, the number of series-connected cells 33 does not have to be the same for all cell arrangements 31, 32, but may be different.

[0057] Figure 4 A schematic diagram of a charging device 40 for a battery cell 30 is shown. The battery cell 30 is, for example, Figure 1 or Figure 3 The charging device 40 has contact pairs (without reference numerals) corresponding to the battery cells 30, so that each cell arrangement 31, 32 of the battery cell 30 can be charged individually. In this example, the charging device 40 has corresponding controlled current sources (without reference numerals) for this purpose, which are configured to provide a controlled charging current at a specific charging voltage.

[0058] If reference Figure 3The battery unit 30 depicted has a maximum of fourteen lithium-ion cells 33 (see Figure 3 ), the maximum charging voltage is then 58.8 V (4.2 V per cell) and is therefore advantageously below the protective undervoltage threshold of 60 V.

[0059] Figure 4 The dashed box in FIG. 2 is used to indicate a system 200 , which includes a battery unit 30 having a plurality of battery cell devices 31 , 32 , and a charging device 40 .

[0060] List of Reference Numerals

[0061] 1Battery-operated handheld power tools

[0062] 2 Control device

[0063] 3 switches

[0064] 3A MOSFET

[0065] 3B MOSFET

[0066] 3CMOSFET

[0067] 3D MOSFET

[0068] 4 Receiving cabin

[0069] 5 Main switch

[0070] 10 battery cells

[0071] 20 battery cells

[0072] 30 battery cells

[0073] 31 battery cell device

[0074] 32-cell device

[0075] 33 battery cells

[0076] 100 systems

[0077] 200 system

[0078] K1 contact

[0079] K1' contact

[0080] K2 contact

[0081] K2' contact

[0082] K3 contact

[0083] K3' contact

[0084] K4 contact

[0085] K4' contact

[0086] P1 pair

[0087] P2 pair

[0088] SIG control signal

Claims

1. A system (100) comprising at least one battery unit (10, 20, 30) and a battery-operated handheld power tool (1), wherein: The at least one battery unit comprises a first battery cell device (31) and a second battery cell device (32) or a first battery unit (10) and a second battery unit (20); wherein the handheld power tool has a receiving compartment (4) for releasably receiving the at least one battery unit (10, 20, 30), wherein the receiving compartment (4) has at least four electrical contacts (K1-K4), the at least four electrical contacts being used to make contact with at least four corresponding contacts of the at least one battery unit (10, 20, 30), wherein the load of the handheld power tool (1) is connected between the first contact (K1) and the fourth contact (K4), wherein a switch (3) capable of switching between an open switch state and a closed switch state is connected to the second contact (K1). A switch (3) is provided between a first contact (K2) and a third contact (K3), and wherein, via the switch (3), the first cell device (31) and the second cell device (32) of the at least one battery cell (10, 20, 30) are connected in series or the first cell (10) and the second cell (20) are connected in series, wherein the switch (3) comprises a semiconductor device comprising two MOSFETs (3A, 3B) connected in series with opposite polarities; and the at least one battery cell further comprises a plurality of contacts (K1', K2', K3', K4') arranged in pairs, wherein respective pairs of the plurality of contacts are connected to an associated one of the first cell device (31) and the second cell device (32).

2. The system (100) according to claim 1, characterized in that The switch (3) is a switch that can be manually operated by a user of the handheld power tool (1).

3. The system (100) according to claim 1, characterized in that The semiconductor device can be changed to an open switch state or a closed switch state by a specific control signal (SIG).

4. The system (100) according to claim 3, characterized in that The control device (2) is configured to output the control signal (SIG) based on the actuation of the main switch (5) of the handheld power tool (1).

5. The system (100) according to claim 1, characterized in that The semiconductor device includes two further MOSFETs (3C, 3D), the two MOSFETs (3A, 3B) and the two further MOSFETs (3C, 3D) being arranged in two pairs (P1, P2), which are connected in parallel to each other.

6. The system (100) according to claim 1, characterized in that Each of the first battery cell device (31) and the second battery cell device (32) has a maximum output voltage lower than 60V.

7. The system (100) according to claim 6, characterized in that Each of the first battery cell device (31) and the second battery cell device (32) includes a plurality of lithium-ion battery cells (33).

8. The system (100) according to claim 7, characterized in that Each of the first battery cell device (31) and the second battery cell device (32) has a maximum of 14 lithium-ion battery cells (33) connected in series.

9. The system (100) according to any one of claims 1 to 8, characterized in that The battery unit (30) has exactly two cell arrangements (31, 32) and four contacts (K1', K2', K3', K4') leading to the outside.

10. The system (100) according to any one of claims 1 to 8, characterized in that The battery unit (30) has exactly three cell arrangements (31, 32) and six contacts (K1', K2', K3', K4') leading to the outside.

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