RESTART PROTECTION DEVICE

Abstract

The invention relates to a restart protection device (1) for a battery-powered electric hand tool (2), comprising—a control capacitor (C.sub.CTRL) having a cathode and an anode, wherein the cathode can be connected to an earth connection (10) of the electric hand tool (2) and the anode can be connected via a battery pack interface (4) of the electric hand tool (2) to a connector wire (6) of a battery pack (3) of the electric hand tool (2); —a controllable discharge circuit (14) designed for discharging the control capacitor (C.sub.CTRL), wherein a control input of the discharge circuit (14) can be connected via the battery pack interface (4) to a signal line (9) of the battery pack (3); —a measuring device (15) designed to determine a charge state of the control capacitor (C.sub.CTRL); and—a control device (13) connected to the measuring device (15), which control device is configured to inhibit start-up of the electric hand tool (2) if the charge state of the control capacitor (C.sub.CTRL) determined by means of the measuring device (15) is below a specified threshold value and an operating switch (12) on the electric hand tool (2) is pressed at the same time.

Claims

1-14. (canceled)

15. A restart protection device, comprising: a control capacitor having a cathode and an anode, wherein the cathode is configured to be connected to a ground connection of a battery-operated electric power tool, and the anode is configured to be connected, via a battery-pack interface of the battery-operated electric power tool, to a connection line of a battery pack of the battery-operated electric power tool; a controllable discharge circuit for discharging the control capacitor, wherein a control input of the discharge circuit is configured to be connected to a signal line of the battery pack via the battery-pack interface; a measuring element for detecting a charge state of the control capacitor; and a controller connected to the measuring element, wherein the controller is configured to block a starting of the battery-operated electric power tool when an operating switch of the electric power tool is actuated, and at the same time, the charge state of the control capacitor detected by the measuring element is below a defined threshold value.

16. The restart protection device of claim 15, wherein the anode of the control capacitor is configured to be connected to the connection line of the battery pack via a charging resistor.

17. The restart protection device of claim 15, wherein the discharge circuit has a controlled switch configured to be connected in parallel with the control capacitor.

18. The restart protection device of claim 15, wherein the control input of the discharge circuit is configured to be connected via a pull-up resistor to a supply connection of the battery-operated electric power tool, or via a pull-down resistor to the ground connection of the battery-operated electric power tool.

19. The restart protection device of claim 18, wherein a resistance of the pull-up resistor or the pull-down resistor is higher than an electrical series resistance between the control input of the discharge circuit and the signal line of the battery pack.

20. The restart protection device of claim 15, wherein the threshold value is one or more of greater than 25% of a supply voltage of the battery pack, greater than 50% of the supply voltage of the battery pack, greater than 75% of the supply voltage of the battery pack, and greater than 90% of the supply voltage of the battery pack.

21. The restart protection device of claim 15, wherein the measuring element for detecting the charge state has a controlled switch, wherein the controlled switch is configured to connect the measuring element to the anode of the control capacitor, and wherein the controlled switch comprises a semiconductor switch.

22. The restart protection device of claim 21, wherein the controller is configured to connect the measuring element to the anode of the control capacitor using a control signal transmitted to a control input of the controlled switch.

23. A battery-operated electric power tool, comprising: a battery pack; a battery pack interface configured to receive the battery pack; and a restart protection device, wherein the restart protection device comprises: a control capacitor having a cathode and an anode, wherein the cathode is connected to a ground connection of the battery-operated electric power tool, and wherein the anode is connected, via the battery-pack interface, to a connection line of the battery pack of the battery-operated electric power tool; a controllable discharge circuit for discharging the control capacitor, wherein a control input of the controllable discharge circuit is connected to a signal line of the battery pack via the battery-pack interface; a measuring element for detecting a charge state of the control capacitor; and a controller connected to the measuring element, wherein the controller is configured to block a starting of the electric power tool when an operating switch of the electric power tool is actuated, and at the same time, the charge state of the control capacitor detected by the measuring element is below a defined threshold value.

24. The battery-operated electric power tool of claim 23, wherein the anode of the control capacitor is connected to the connection line of the battery pack via a charging resistor, and wherein the connection line is a supply line of the battery pack or is the signal line of the battery pack.

25. The battery-operated electric power tool of claim 24, wherein the control input of the discharge circuit is connected via a pull-up resistor to a supply connection of the battery-operated electric power tool, or via a pull-down resistor to the ground connection of the battery-operated electric power tool, and wherein the restart protection device further comprises: a buffer capacitor, wherein the buffer capacitor is configured to compensate for overvoltages between the ground connection of the battery-operated electric power tool and the supply connection of the battery-operated electric power tool, and wherein the buffer capacitor is an electrolytic capacitor.

26. The battery-operated electric power tool of claim 25, wherein a resistance of the pull-up resistor or the pull-down resistor is higher than an electrical series resistance between the control input of the controllable discharge circuit and the signal line of the battery pack.

27. The battery-operated electric power tool of claim 23, wherein the threshold value is one or more of greater than 25% of a supply voltage of the battery pack, greater than 50% of the supply voltage of the battery pack, greater than 75% of the supply voltage of the battery pack, and greater than 90% of the supply voltage of the battery pack.

28. The battery-operated electric power tool of claim 23, wherein the measuring element for detecting the charge state comprises a controlled switch, and wherein the controlled switch is configured to connect the measuring element to the anode of the control capacitor, and wherein the controlled switch comprises a semiconductor switch.

29. The battery-operated electric power tool of claim 28, wherein the controller is configured to connect the measuring element to the anode of the control capacitor using a control signal transmitted to a control input of the controlled switch.

30. The battery-operated electric power tool of claim 23, wherein the controllable discharge circuit comprises a controlled switch configured to be connected in parallel with the control capacitor.

31. A restart protection method for a battery-operated electric power tool, the method comprising: inserting a battery pack into the battery-operated electric power tool; charging a control capacitor based at least in part on the inserting; detecting a charge state of the control capacitor; blocking a starting of the battery-operated electric power tool when an operating switch of the battery-operated electric power tool is actuated, wherein the blocking is based at least in part on detecting the charge state of the control capacitor is below a defined threshold value; monitoring, using a discharge circuit, a signal line of the battery pack; detecting a removal of the battery pack from the battery-operated electric power tool based at least in part on the monitoring; and discharging, using the discharge circuit, the control capacitor, wherein the discharging is based on detecting the removal of the battery pack from the battery-operated electric power tool.

32. The restart protection method of claim 31, further comprising: connecting a charging resistor in series with the control capacitor, wherein the charging resistor is configured to delay the charging of the control capacitor; and wherein one or more electrical components of the battery-operated electric power tool are given sufficient time for a boot process based in part on the delaying.

33. The restart protection method of claim 31, wherein the discharge circuit comprises a controlled switch, the method further comprising: connecting the controlled switch in parallel with the control capacitor.

34. The restart protection method of claim 31, wherein the threshold value is one or more of greater than 25% of a supply voltage of the battery pack, greater than 50% of the supply voltage of the battery pack, greater than 75% of the supply voltage of the battery pack, and greater than 90% of the supply voltage of the battery pack.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0071] In the figures, functionally identical elements are denoted the same references.

[0072] There are shown, in schematic form:

[0073] FIG. 1 illustrates a circuit diagram of a restart protection device for a battery-operated electric power tool having a battery pack connected to an electric power tool pack, according to an embodiment of the disclosure; and

[0074] FIG. 2 illustrates a circuit diagram of a restart protection device, according to an alternate embodiment of the disclosure.

DETAILED DESCRIPTION

[0075] Shown schematically in FIG. 1 is an exemplary embodiment of a restart protection device 1 according to the disclosure for a battery-operated electric power tool 2.

[0076] The electric power tool 2 has at least one battery pack 3 and at least one battery-pack interface 4 for receiving the at least one battery pack 3. In the exemplary embodiment, the disclosure is shown on the basis of the use of exactly one battery pack 3 and exactly one battery-pack interface 4—however, this is not to be understood as restrictive.

[0077] The battery pack 3 may have one or more accumulator cells 5, which are usually connected to each other in series and together generate the supply voltage V.sub.BAT (battery voltage) of the battery pack 3. The battery pack 3 represented as an example has a connection line, realized as a supply line 6, and a ground line 7 carrying a ground potential GND, which are connected to the electric power tool 2 via the battery-pack interface 4 for the purpose of supplying the electric power tool 2.

[0078] Furthermore, the battery pack 3 has a battery management system 8, which in the exemplary embodiment is provided for monitoring the temperature of the battery pack 3. Provided for the purpose of transmitting the temperature signal to the electric power tool 2 there is a signal line, in this case a temperature control line 9, which is connected to the electric power tool 2 by means of the battery-pack interface 4.

[0079] The electric power tool 2 represented further comprises a buffer capacitor C.sub.B, in particular an electrolytic capacitor, for compensating overvoltages between a ground connection 10 of the electric power tool 2 and a supply connection 11 of the electric power tool 2. However, the buffer capacitor C.sub.B is not absolutely necessary within the scope of the disclosure; the disclosure is, however, particularly advantageous for use with an electric power tool 2 that has such a buffer capacitor C.sub.B. The buffer capacitor C.sub.B is shown as a dashed line in FIG. 1.

[0080] Furthermore, the electric power tool 2 has an operating switch 12 for selectively switching on or off a motor M of the electric power tool 2. The operating switch 12 can be locked in its switch-on position.

[0081] The restart protection device 1 comprises a control capacitor C.sub.CTRL having a cathode and an anode, the cathode being electrically connected to the ground connection 10 of the electric power tool 2 and the anode being electrically connected to a connection line of the battery pack 3 via the battery-pack interface 4 of the electric power tool 2. In the exemplary embodiment, the connection line is the supply line 6 of the battery pack 3. In principle, however, it may also be the signal line, for example the temperature control line 9 or another signal line of the battery pack 3.

[0082] The control capacitor C.sub.CTRL is charged if a battery pack 3 is inserted into the electric power tool 2 or if the supply voltage V.sub.BAT of the battery pack 3 is present. In the exemplary embodiment, the charging of the control capacitor C.sub.CTRL is delayed by the use of charging resistor R.sub.L connected ahead in series. The delay, or the charging resistor R.sub.L, in this case may be dimensioned in such a manner that the control means 13, described below, and/or other electrical components of the electric power tool 2 have sufficient time for a boot process in order to reliably recognize a restart protection event. The use of a charging resistor R.sub.L is optional.

[0083] The restart protection device 1 also has a controllable discharge circuit 14 designed for discharging the control capacitor C.sub.CTRL, a control input of the discharge circuit 14 being connected via the battery-pack interface 4 to a signal line of the battery pack 3, in this case to the temperature control line 9 of the battery pack 3. A removal of the battery pack 3 from the electric power tool 2 or a drop in the supply voltage of the battery pack 3 can thus be detected by monitoring of the temperature control line 9 of the battery pack 3 by the discharge circuit 14, whereupon the discharge circuit 14 discharges the control capacitor C.sub.CTRL in a controlled manner. For example, it may be provided that the discharge circuit 14 establishes a high-impedance connection between the cathode and the anode of the control capacitor C.sub.CTRL if the control input of the discharge circuit 14 is connected to the supply potential V.sub.BAT, and otherwise establishes a low-impedance connection between the anode and the cathode of the control capacitor C.sub.CTRL Thus, in particular, if the temperature control line 9 of the battery pack 3 carries a potential different from the ground potential GND in the idle state (e.g. no-load state), the presence of the battery pack 3 can be recognized without data actually being transmitted via the temperature control line 9. If the battery pack 3 is removed, a pull-down resistor R.sub.PD, for example, may connect the control input of the discharge circuit 14 to the ground connection 10 of the electric power tool 2. Alternatively, a pull-up resistor R.sub.PU may connect the control input of the discharge circuit 14 to the supply connection 11 of the electric power tool 2. The exemplary embodiment in FIG. 1 shows a variant having a pull-down resistor R.sub.PD, and the exemplary embodiment in FIG. 2 shows a pull-up resistor R.sub.PU.

[0084] In principle, it should be noted that each electrical resistor mentioned in this description may also be composed of a plurality of individual resistors, as represented in the example of the pull-up resistor R.sub.PU in FIG. 2. This also applies analogously to other electrical components.

[0085] The restart protection device 1 is thus able to initiate discharging of the control capacitor C.sub.CTRL as soon as the supply voltage V.sub.BAT of the battery pack 3 drops, or the battery pack 3 is removed, although a possibly present buffer capacitor C.sub.B continues to keep the supply voltage V.sub.BAT constant.

[0086] The restart protection device 1 further comprises a measuring means 15 designed to detect the charge state of the control capacitor C.sub.CTRL, and a control means 13 that is connected to the measuring means 15 and that is configured to block the starting of the electric power tool 2 if the charge state of the control capacitor C.sub.CTRL detected by means of the measuring means 15 is below a defined threshold value and at the same time the operating switch 12 of the electric power tool 2 is actuated, for example is locked.

[0087] Thus, the control means 13 detects the charge state of the control capacitor C.sub.CTRL by means of the measuring means 15, and blocks the starting of the motor M of the electric power tool 2 in the case of a restart protection event.

[0088] For rapid detection of a restart protection event it may be advantageous in this case if the threshold value is greater than 25% of the supply voltage V.sub.BAT of the battery pack 3, preferably greater than 50% of the supply voltage V.sub.BAT of the battery pack 3, particularly preferably greater than 75% of the supply voltage V.sub.BAT of the battery pack 3, for example even greater than 90% of the supply voltage V.sub.BAT of the battery pack 3.

[0089] Furthermore, it may be provided that the measuring means 15 has a controlled switch T.sub.M (cf. FIG. 2), in particular a semiconductor switch, via which the measuring means 15 can be connected to the anode of the control capacitor C.sub.CTRL for the purpose of detecting the charge state as required. For this purpose, the control means 13 may be configured, for example, to connect the measuring means 15 to the anode of the control capacitor C.sub.CTRL by means of a control signal U.sub.M (shown as a dashed line in FIG. 1) transmitted to the control input of the controlled switch T.sub.M of the measuring means 15, for the purpose of detecting the charge state of the control capacitor C.sub.CTRL.

[0090] The control means 13 may be any control means of the electric power tool 2, which may also be such that it can be used for other tasks within the electric power tool 2.

[0091] FIG. 2 shows a further embodiment of the present disclosure, on the basis of a further circuit diagram in a partially more detailed view. In the following, it is substantially the differences compared with the exemplary embodiment represented in FIG. 1 that are discussed.

[0092] In the exemplary embodiment of FIG. 2, the discharge circuit 14 for discharging the control capacitor C.sub.CTRL has a controlled switch connected in parallel with the control capacitor C.sub.CTRL, in the exemplary embodiment an n-channel MOSFET T.sub.D. The gate terminal of the n-channel MOSFET T.sub.D is electrically connected to the temperature control line 9 of the battery pack 3, which carries the ground potential GND in the “idle state” and thus switches the n-channel MOSFET T.sub.D to high impedance on the output side when the battery pack 3 is inserted into the electric power tool 2. The control capacitor C.sub.CTRL is thus able to charge itself via the charging resistor R.sub.L. If the battery pack 3 is removed, and thus also the ground connection to the temperature control line 9, a pull-up resistor R.sub.PU can connect the gate terminal of the n-channel MOSFET T.sub.D to the supply voltage V.sub.BAT, which may be buffered by means of the buffer capacitor C.sub.B.

[0093] Advantageously, the pull-up resistor R.sub.PU or the pull-down resistor R.sub.PD has a higher resistance than an electrical series resistor R.sub.S between the control input of the discharge circuit 14 and the signal line, or temperature control line 9, of the battery pack 3. In this way, parasitic discharge currents can be suppressed as far as possible when the battery pack 3 is inserted.

[0094] In the exemplary embodiment of FIG. 2, the measuring means 15 moreover likewise has an n-channel MOSFET T.sub.M, via which the anode of the control capacitor C.sub.CTRL is connected to the control means 13. Thus, an input of the control means 13, for example an analogue-digital converter of an input of the control means 13, may be used to detect the charge state. As already mentioned, it may also be provided in this case that the control means 13 controls the connection of the measuring means 15 to the anode of the control capacitor C.sub.CTRL by means of a control signal U.sub.M. However, this is not absolutely necessary; it may also be provided that the measuring means 15 is permanently connected to the anode of the control capacitor C.sub.CTRL. For this purpose, the exemplary embodiment of FIG. 2 shows, by way of example, that the control input, or the gate terminal, of the n-channel MOSFET T.sub.M is permanently set to a potential of +5 volts.