WO2019065978A1

WO2019065978A1 - Electric tool and attachment

Info

Publication number: WO2019065978A1
Application number: PCT/JP2018/036287
Authority: WO
Inventors: 元治武藤; 直規鶴田; 昌樹池田
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2017-09-29
Filing date: 2018-09-28
Publication date: 2019-04-04
Also published as: JP2019063929A; EP3689552A1; EP3689552A4; JP7108911B2

Abstract

The present invention addresses the problem of providing an electric tool and an attachment with which it is possible to restrict an electric influence on a tool main body due to an abnormality of the attachment. An electric tool (10) is provided with a tool main body (20) and an attachment (30) which removably attached to the tool main body (20). The attachment (30) comprises: an operating unit (32) which operates by means of electric power supplied from the tool main body (20); and a limiting unit (33) which limits the supply of electric power from the tool main body (20) to the operating unit (32) when there is an abnormality in the attachment (30).

Description

Power tool, attachment

The present disclosure relates generally to power tools and attachments, and more particularly to power tools having a tool body and an attachment removably attached to the tool body, and attachments for power tools.

Patent Document 1 discloses a power tool. The electric power tool of Patent Document 1 is an electric power tool with an attachment in which a dust collector (attachment) is attached to a hammer drill (tool main body). In Patent Document 1, a male terminal is protruded from a dust collecting apparatus, and a socket through which a male terminal can be inserted into a hammer drill, and a female positioned inside the socket and electrically connectable with the male terminal. Terminals are provided respectively. Then, a drive source is supplied from the battery pack to the dust collection device by the electrical connection between the male terminal and the female terminal accompanying the coupling of the dust collection device to the hammer drill.

In Patent Document 1, the dust collection device (attachment) has a motor (operating unit) driven by the power from the electric power tool. Therefore, when an abnormality occurs in the motor, there is a possibility that the hammer drill (the tool body of the power tool) may receive an electrical influence due to the abnormality in the motor.

JP 2011-189486 A

An object of the present disclosure is to provide a power tool and an attachment capable of suppressing an electrical influence on the tool body due to an abnormality of the attachment.

The power tool according to one aspect of the present disclosure includes a tool body and an attachment removably attached to the tool body. The attachment includes an operating unit operated by power supplied from the tool body, and a limiting unit for limiting supply of power from the tool body to the operating unit when the attachment is abnormal.

The attachment of one aspect of the present disclosure is an attachment that is removably attached to the tool body of the power tool. The attachment includes an operating unit operated by power supplied from the tool body, and a limiting unit for limiting supply of power from the tool body to the operating unit when the attachment is abnormal.

FIG. 1 is a block diagram of a power tool according to an embodiment of the present disclosure. FIG. 2 is a perspective view of the power tool. FIG. 3 is a block diagram of the main part of the power tool. FIG. 4 is a block diagram of an attachment according to a first modification of the embodiment. FIG. 5 is a block diagram of an attachment according to a second modification of the embodiment.

1. Embodiment 1.1 Overview FIG. 1 shows a block diagram of a power tool 10 of the present embodiment. The power tool 10 includes a tool body 20 and an attachment 30 removably attached to the tool body 20. The attachment 30 has an operation unit 32 operated by the power supplied from the tool body 20, and a restriction unit 33 for restricting the supply of power from the tool body 20 to the operation unit 32 when the attachment 30 is abnormal.

In the power tool 10, when an abnormality occurs in the operation unit 32 of the attachment 30, the restriction unit 33 restricts the supply of power from the tool body 20 to the operation unit 32. For example, there is a possibility that the power supplied from the tool main body 20 to the operation unit 32 becomes excessively large due to the abnormality of the operation unit 32. Even in such a case, the limiting unit 33 limits the supply of power from the tool body 20 to the operating unit 32. Therefore, in the power tool 10, it is possible to suppress the electrical influence on the tool main body 20 due to the abnormality of the attachment 30.

1.2 Configuration Hereinafter, the power tool 10 will be described in more detail. The power tool 10 is a hammer drill as shown in FIG. 2 and includes a battery pack 40 in addition to the tool body 20 and the attachment 30 described above.

The battery pack 40 serves as a power source for the tool body 20 and the attachment 30. The battery pack 40 includes a main body connection portion 41 and a battery circuit 42, as shown in FIG. In addition, the battery pack 40 includes a housing 400 that accommodates the main body connection portion 41 and the battery circuit 42 (see FIG. 2).

The body connection portion 41 is an element for electrically and mechanically connecting the battery pack 40 to the tool body 20. The main body connection portion 41 has a mechanical structure (e.g., a structure that engages with the housing 200 of the tool body 20) and an electrical structure (e.g., a tool) for realizing removable attachment of the battery pack 40 to the tool body 20. It is a connector which has a terminal for connection with the electric circuit of main part 20). Such a main body connection portion 41 can be realized by a known technique, and thus the detailed description is omitted.

The battery circuit 42 is a circuit for supplying power to the tool main body 20 via the main body connection portion 41. The battery circuit 42 includes a secondary battery and a charge / discharge circuit of the secondary battery. The charge / discharge circuit has a function (discharge function) of outputting the power of the secondary battery from the main body connection portion 41, and a function (charge function) of charging the secondary battery by the power from the external power supply. However, the charge and discharge circuit is not essential.

As shown in FIG. 1, the tool body 20 includes a power supply connection unit 21, an attachment connection unit 22, an operation unit 23, an operation unit 24, a first output control unit 25, and a second output control unit 26. An operation control unit 27 and a power supply unit 28 are provided. Moreover, the tool main body 20 is further provided with the protective circuit 29, as shown in FIG. Furthermore, the tool main body 20 is provided with the housing | casing 200 (refer FIG. 2). The housing 200 includes the power supply connection unit 21 shown in FIG. 1, the attachment connection unit 22, the operation unit 23, the operation unit 24, the first output control unit 25, the second output control unit 26, and the operation control unit A power supply unit 28 and a protection circuit 29 are accommodated.

The power supply connection 21 is an element for connecting the battery pack 40 to the tool body 20 electrically and mechanically. The power supply connection portion 21 has a mechanical structure (a structure to be fitted to the housing 400 of the battery pack 40) and an electrical structure (the battery pack 40 for realizing removable attachment of the battery pack 40 to the tool main body 20). (A terminal for connection to a circuit). The power supply connection portion 21 corresponds to the main body connection portion 41 of the battery pack 40, and by connecting the main body connection portion 41 to the power supply connection portion 21, the battery pack 40 is removably attached to the tool main body 20. Such a power supply connection unit 21 can be realized by a known technique, and thus the detailed description is omitted.

The attachment connection 22 is an element for electrically and mechanically connecting the attachment 30 to the tool body 20. The attachment connection 22 is a connector having a mechanical structure (e.g., a structure that mates with the housing 300 of the attachment 30) and an electrical structure for achieving removable attachment of the attachment 30 to the tool body 20. The attachment connection part 22 has a terminal (a pair of output terminal 221,222) for a connection with the electric circuit of the attachment 30 as an electric structure, as shown in FIG. Such an attachment connection portion 22 can be realized by a known technique, and thus the detailed description is omitted.

The operating unit 23 has a mechanical structure and an electrical structure for realizing the function as the tool body 20. The operating unit 23 includes a holder 231 for holding the tip tool 50 (see FIG. 2), and a motor for rotating the tip tool 50 held by the holder 231. In addition, the operation unit 23 includes a handle 232 for moving the tip tool 50 held by the holder 231 along the direction (front-rear direction) of the rotation axis of the tip tool 50. By using the handle 232, the position of the holder 231 (the position of the tip tool 50) relative to the attachment 30 can be adjusted. As shown in FIG. 2, the tip of the tip tool 50 can be taken out of the attachment 30. The tip tool 50 is, for example, a gon bit, a drill bit, a driver bit, an iron drill, a wood drill. The tip tool 50 is not included in the components of the operation unit 23 because it is replaced as necessary.

The operation unit 24 is an interface for the user to operate the tool body 20. The operation unit 24 has a trigger switch 241 for operating the operation unit 23, as shown in FIG.

The first output control unit 25 generates power (first drive power) for operating the operation unit 23 of the tool main body 20 using the power supplied from the battery pack 40 via the power supply connection unit 21. And has a function of outputting to the operation unit 23. The first output control unit 25 is controlled by the operation control unit 27 to apply a predetermined voltage or current to the operation unit 23. The first output control unit 25 can be realized, for example, by a known technique such as a switching power supply, and thus the detailed description is omitted.

The second output control unit 26 generates power (second drive power) for operating (the operation unit 32 of) the attachment 30 using power supplied from the battery pack 40 via the power supply connection unit 21. , And has a function of outputting to the attachment connection portion 22. The second output control unit 26 is controlled by the operation control unit 27, and outputs a predetermined voltage or current through the pair of

output terminals

221 and 222 of the attachment connection unit 22. Thus, the tool body 20 is configured to supply power to the attachment 30 based on the power received at the power connection 21. Therefore, power can be supplied to the tool body 20 and the attachment 30 by one battery pack 40. The second output control unit 26 can be realized by, for example, a known technique such as a switching power supply, and thus the detailed description is omitted.

The operation control unit 27 has a function (control function) of controlling the first output control unit 25 and the second output control unit 26 according to the operation of the operation unit 24. For example, while the trigger switch 241 of the operation unit 24 is on, the operation control unit 27 causes the first output control unit 25 to output the first drive power to the operation unit 23, and the attachment from the second output control unit 26. The connection 22 is caused to output the second drive power. The operation control unit 27 includes one or more processors and one or more memories, and the one or more processors execute the one or more programs stored in the one or more memories to realize the control function.

The power supply unit 28 generates power (control power) for operating the operation control unit 27 of the tool main body 20 using the power supplied from the battery pack 40 via the power supply connection unit 21, and performs operation control. It has a function of outputting to the part 27. The power supply unit 28 can be realized by, for example, a known technique such as a regulator (three-terminal regulator), and thus the detailed description is omitted.

The protection circuit 29 has a current fuse 291 (see FIG. 3). The current fuse 291 is located between one of the pair of output terminals 221 and 222 (output terminal 221) of the attachment connection 22 and the second output control unit 26. The rated current value of the current fuse 291 is determined based on the range of the normal operating current of the operating unit 32 of the attachment 30. Specifically, the rated current value of the current fuse 291 is set such that the current fuse 291 is fused when the attachment 30 is abnormal.

As shown in FIG. 1, the attachment 30 includes a main body connection portion 31, an operation portion 32, and a restricting portion 33. Moreover, the attachment 30 is provided with the housing | casing 300 which accommodates the main-body connection part 31, the operation part 32, and the limitation part 33 (refer FIG. 2). In the present embodiment, the attachment 30 is a dust collector. That is, the attachment 30 is used to collect dust (wood scraps, iron scraps, etc.) generated when the tool body 20 is used. As shown in FIG. 2, a dust box 34 for containing the dust collected by the dust collection device can be removably attached to the housing 300 of the attachment 30.

The main body connection portion 31 is an element for electrically and mechanically connecting the attachment 30 to the tool main body 20. The main body connection portion 31 is a connector having a mechanical structure (a structure to be fitted with the housing of the tool main body 20) and an electrical structure for realizing the removable attachment of the attachment 30 to the tool main body 20. As shown in FIG. 3, the main body connection portion 31 has terminals (a pair of input terminals 311 and 312) for connection to the electric circuit of the tool main body 20 as an electrical structure. The main body connection portion 31 corresponds to the attachment connection portion 22 of the tool main body 20, and the attachment 30 is detachably attached to the tool main body 20 by connecting the main body connection portion 31 to the attachment connection portion 22. At this time, the pair of

input terminals

311 and 312 of the main body connection portion 31 are electrically connected to the pair of

output terminals

221 and 222 of the attachment connection portion 22, respectively.

The operating unit 32 has a mechanical structure and an electrical structure for realizing the function as the attachment 30. In the present embodiment, since the attachment 30 is a dust collector, the operation unit 32 is a suction device for sucking dust generated by use of the tool main body 20 to the dust box 34, and the motor 321 is provided as an electrical structure. doing. That is, by the operation of the motor 321 of the operation unit 32, dust is collected to the dust box 34 by the suction device. The motor 321 is connected between the pair of

input terminals

311 and 312 of the main body connection portion 31, as shown in FIG. The operating unit 32 (motor 321) is configured to operate by a voltage applied between the pair of

input terminals

311 and 312.

As the abnormality of the attachment 30, a failure of the motor 321 of the operation unit 32 is assumed. Examples of failure of the motor 321 include locking (sticking) of the motor 321 and dielectric breakdown of the motor 321. When such a failure of the motor 321 occurs, an unexpected excessive current may flow to the motor 321 (that is, the operation unit 32).

The limiting unit 33 has a current fuse 331. The current fuse 331 is located between one of the pair of input terminals 311 and 312 (input terminal 311) of the main body connection portion 31 and the motor 321 of the operation unit 32. That is, the limiting unit 33 includes the current fuse 331 in the electric path for supplying the power supplied from the tool main body 20 to the operation unit 32. The rated current value of the current fuse 331 is determined based on the range of the normal operating current of the operating unit 32 of the attachment 30. Specifically, the rated current value of the current fuse 331 is set so that the current fuse 331 is melted down when the attachment 30 is abnormal. Here, as shown in FIG. 3, the tool main body 20 has a current fuse 291 between the second output control unit 26 and the output terminal 221. In other words, the tool body 20 has the current fuse 291 electrically connected in series to the current fuse 331. However, the rated current value of the current fuse 331 of the limiting unit 33 is smaller than the rated current value of the current fuse 291 of the tool main body 20. As a result, when the attachment 30 is abnormal, the current fuse 331 is more likely to be melted earlier than the current fuse 291. That is, even if the tool main body 20 has the current fuse 291, the current fuse 291 of the attachment 30 is melted first. Therefore, even if an abnormality occurs in the attachment 30, there is a high possibility that the current fuse 291 of the tool main body 20 need not be replaced with a new one.

When using the power tool 10 described above, the battery pack 40 and the attachment 30 are attached to the tool body 20. Here, the tool body 20 has a power supply connection portion 21 to which the battery pack 40 is attached, and is configured to operate by the power received by the power supply connection portion 21. That is, the tool body 20 is a battery-powered electric tool. Therefore, it is not necessary to connect the tool main body 20 with an outlet and a cable, and the handleability is improved. Moreover, the tool main body 20 has the attachment connection part 22 which has a pair of output terminal 221,222. The attachment 30 has a pair of

input terminals

311 and 312 electrically connected to the pair of

output terminals

221 and 222, respectively, and has a main body connection portion 31 removably attached to the attachment connection portion 22. The operating unit 32 is configured to operate by a voltage applied between the pair of

input terminals

311 and 312. Therefore, the number of terminals required for the power supply from the tool main body 20 to the attachment 30 can be reduced. Therefore, an inexpensive connector with a small number of terminals can be used for the attachment connection portion 22 and the main body connection portion 31, and cost reduction can be expected.

1.3 Operation at Abnormality Next, the operation of the electric power tool 10 at the time of abnormality of the attachment 30 will be described. When an abnormality occurs in the attachment 30, the current flowing to the operation unit 32 (motor 321) increases. Here, when the value of the current flowing through the motor 321 exceeds the rated current value of the current fuse 331 of the limiting unit 33, the current fuse 331 is melted and cut. As a result, the motor 321 is electrically separated from the input terminal 311 of the main body connection portion 31, and as a result, the motor 321 is also electrically separated from the tool main body 20 (the second output control portion 26). Thus, the limiting unit 33 limits the supply of power from the tool main body 20 to the operating unit 32 when the attachment 30 is abnormal. Therefore, in the power tool 10, it is possible to suppress the electrical influence on the tool main body 20 due to the abnormality of the attachment 30.

In the present embodiment, the current fuse 331 of the limiting unit 33 is melted to limit the supply of power from the tool main body 20 to the operation unit 32. However, since the current fuse 291 of the tool body 20 is less likely to be broken, there is a high possibility that the tool body 20 need not be repaired or replaced. Therefore, it can be expected that only the repair of the attachment 30, the replacement of parts, or the replacement of the attachment 30 itself is required. Further, in the limiting unit 33, the function of limiting the supply of power from the tool main body 20 to the operating unit 32 is realized by the current fuse 331. Therefore, the configuration can be simplified, and cost reduction can be expected.

2. Modified Example The above-described embodiment described above is only one of various embodiments of the present disclosure. Further, various changes can be made to the above-described embodiment according to the design and the like as long as the object of the present disclosure can be achieved. Below, the modification of the said embodiment is enumerated.

2.1 First Modified Example FIG. 4 shows an attachment 30A of a first modified example. The attachment 30A includes a main body connection portion 31, an operation portion 32, and a restriction portion 33A.

The operating unit 32 includes a motor 321. The motor 321 is connected between the pair of

input terminals

311 and 312 of the main body connection portion 31.

The limiting unit 33A includes a switch 331A and a control circuit 332A.

The switch 331 </ b> A is in an electric path that supplies the power supplied from the tool body 20 to the operation unit 32. As shown in FIG. 4, the switch 331 </ b> A is inserted between the motor 321 and the input terminal 312 of the main body connection portion 31. More specifically, the switch 331A is a field effect transistor (FET), the drain of the switch 331A is electrically connected to the motor 321, and the source of the switch 331A is electrically connected to the input terminal 312. The switch 331A may be a semiconductor switch element other than the FET, or may be another controllable switch (such as an electromagnetic relay).

Control circuit 332A controls switch 331A when the current flowing to operation unit 32 exceeds a predetermined value, and restricts the supply of power from tool body 20 to operation unit 32. The control circuit 332A includes a power supply circuit 333A and a drive circuit 334A.

The power supply circuit 333A is a circuit for supplying drive power to the drive circuit 334A. The power supply circuit 333A includes a transistor Tr10, a resistor R10, and a zener diode ZD10. The transistor Tr10 is electrically connected between the pair of

input terminals

311 and 312 of the main body connection portion 31. The transistor Tr10 is an NPN transistor, the collector of the transistor Tr10 is electrically connected to the input terminal 311, and the emitter of the transistor Tr10 is electrically connected to the input terminal 312. The resistor R10 is electrically connected between the collector and the base of the transistor Tr10. The cathode of the Zener diode ZD10 is electrically connected to the base of the transistor Tr10, and the anode of the Zener diode ZD10 is electrically connected to the ground. Such a power supply circuit 333A reduces the voltage between the pair of

input terminals

311 and 312 to a range suitable for driving the drive circuit 334A. The configuration of the power supply circuit 333A is well known, so detailed description will be omitted.

The drive circuit 334A is a circuit for driving the switch 331A. The drive circuit 334A includes resistors R11, R12 and R13, and a comparator CP10.

The resistors R11 and R12 form a series circuit, and the series circuit is electrically connected between the emitter of the transistor Tr10 of the power supply circuit 333A and the input terminal 312. The resistor R13 is electrically connected between the source of the switch 331A and the input terminal 312.

The comparator CP10 has a non-inverted input terminal, an inverted input terminal, and an output terminal. Here, while the voltage applied to the inverting input terminal is less than or equal to the voltage applied to the non-inverting input terminal, the output of the output terminal is at the high level. On the other hand, when the voltage applied to the inverting input terminal exceeds the voltage applied to the non-inverting input terminal, the output of the output terminal changes from high level to low level.

The output terminal of the comparator CP10 is electrically connected to the gate of the switch 331A. The inverting input terminal of the comparator CP10 is electrically connected to the connection point between the source of the switch 331A and the resistor R13. As a result, a voltage (detection voltage) corresponding to the current flowing through the motor 321 is applied to the inverting input terminal of the comparator CP10. The non-inverting input terminal of the comparator CP10 is electrically connected to the connection point of the resistors R11 and R12. As a result, a voltage (reference voltage) for determining whether the value of the current flowing through the motor 321 is an abnormal value is applied to the non-inverting input terminal of the comparator CP10. The reference voltage is a voltage corresponding to the above-described predetermined value, and is determined by the output voltage of the power supply circuit 333A and the resistance value of the resistors R11 and R12. That is, the output voltage of the power supply circuit 333A and the resistance values of the resistors R11 and R12 are determined so that the switch 331A can be turned off when the attachment 30A is abnormal.

Next, the operation of the power tool 10 at the time of abnormality of the attachment 30A will be described. When an abnormality occurs in the attachment 30A, the current flowing to the operation unit 32 (motor 321) increases. Here, when the voltage (detection voltage) applied to the inverting input terminal of the comparator CP10 exceeds the voltage (reference voltage) applied to the non-inverting input terminal of the comparator CP10, the output terminal of the comparator CP10 is high level. And the switch 331A is turned off. Thereby, the motor 321 is electrically separated from the input terminal 312 of the main body connection portion 31, and as a result, the motor 321 is also electrically separated from the tool main body 20 (the second output control portion 26). Thus, the limiting unit 33A limits the supply of power from the tool main body 20 to the operating unit 32 when the attachment 30A is abnormal. Therefore, the electrical influence on the tool body 20 due to the abnormality of the attachment 30A can be suppressed.

Thus, in the first modification, the switch 331A is used to limit the supply of power from the tool body 20 to the operation unit 32. Therefore, unlike the case where a fuse (a current fuse or a thermal fuse) is used to limit the supply of power from the tool body 20 to the operation unit 32, the limiting unit 33A can be used again. Therefore, when an abnormality occurs in the attachment 30A, it is not necessary to replace the part (the switch 331A) of the restriction unit 33A. Further, the limiting unit 33A controls the switch 331A by the control circuit 332A. Therefore, the accuracy of the timing of limiting the supply of the power from the tool main body 20 to the operation unit 32 is improved.

The limiting unit 33A does not necessarily have to turn off the switch 331A. Instead of turning off the switch 331A, the power supplied from the tool body 20 to the operation unit 32 may be limited by operating the switch 331A in the active region.

2.2 Second Modified Example FIG. 5 shows an attachment 30B of a second modified example. The attachment 30B includes a main body connection portion 31, an operation portion 32, and a restriction portion 33B.

input terminals

311 and 312 of the main body connection portion 31.

The limiting unit 33B includes a thermal fuse 331B and a control circuit 332B.

The thermal fuse 331 </ b> B is in an electric path that supplies the power supplied from the tool body 20 to the operation unit 32. As shown in FIG. 5, the thermal fuse 331 </ b> B is inserted between the motor 321 and the input terminal 312 of the main body connection portion 31.

Control circuit 332B melts thermal fuse 331B when the current flowing to operation unit 32 exceeds a predetermined value. The control circuit 332B includes a power supply circuit 333B and a drive circuit 334B.

The power supply circuit 333B is a circuit for supplying drive power to the drive circuit 334B. The power supply circuit 333B has the same configuration as the power supply circuit 333A. Such a power supply circuit 333B reduces the voltage between the pair of

input terminals

311 and 312 to a range suitable for driving the drive circuit 334B.

The drive circuit 334B is a circuit for blowing the thermal fuse 331B. The drive circuit 334B includes resistors R11, R12, and R13, a comparator CP10, a transistor Tr11, and a resistor R14.

The resistors R11 and R12 form a series circuit, and the series circuit is electrically connected between the emitter of the transistor Tr10 of the power supply circuit 333B and the input terminal 312. The resistor R13 is electrically connected between the thermal fuse 331B and the input terminal 312.

The resistor R14 is a resistor for heating and generates heat by energization. One end of the resistor R14 is connected to a predetermined portion of the thermal fuse 331B. The flow of current through the resistor R14 causes the resistor R14 to generate heat, and the heat of the resistor R14 causes the thermal fuse 331B to be blown.

The transistor Tr11 is a field effect transistor (FET). The drain of the transistor Tr11 is electrically connected to the thermal fuse 331B via the resistor R14, and the source of the transistor Tr11 is electrically connected to the ground.

The comparator CP10 has a non-inverted input terminal, an inverted input terminal, and an output terminal. Here, while the voltage applied to the non-inversion input terminal is equal to or less than the voltage applied to the inversion input terminal, the output of the output terminal is at the low level. On the other hand, when the voltage applied to the non-inverted input terminal exceeds the voltage applied to the inverted input terminal, the output of the output terminal changes from low level to high level.

The output terminal of the comparator CP10 is electrically connected to the gate of the transistor Tr11. The noninverting input terminal of the comparator CP10 is electrically connected to the connection point of the temperature fuse 331B and the resistor R13. As a result, a voltage (detection voltage) corresponding to the current flowing through the motor 321 is applied to the non-inverting input terminal of the comparator CP10. The inverting input terminal of the comparator CP10 is electrically connected to the connection point of the resistors R11 and R12. As a result, a voltage (reference voltage) for determining whether the value of the current flowing through the motor 321 is an abnormal value is applied to the inverting input terminal of the comparator CP10. The reference voltage is a voltage corresponding to the above-described predetermined value, and is determined by the output voltage of the power supply circuit 333B and the resistance value of the resistors R11 and R12. That is, the output voltage of the power supply circuit 333B and the resistance values of the resistors R11 and R12 are determined so that the thermal fuse 331B can be blown when the attachment 30B is abnormal.

Next, the operation of the power tool 10 at the time of abnormality of the attachment 30B will be described. When an abnormality occurs in the attachment 30B, the current flowing to the operation unit 32 (motor 321) increases. Here, when the voltage (detection voltage) applied to the non-inversion input terminal of the comparator CP10 exceeds the voltage (reference voltage) applied to the inversion input terminal of the comparator CP10, the output terminal of the comparator CP10 starts from the low level. The high level turns on the transistor Tr11. As a result, current flows through the resistor R14 and the resistor R14 generates heat, and the thermal fuse 331B is melted and broken by the heat of the resistor R14. Therefore, the motor 321 is electrically separated from the input terminal 312 of the main body connection portion 31, and as a result, the motor 321 is also electrically separated from the tool main body 20 (the second output control portion 26). Thus, the limiting unit 33B limits the supply of power from the tool body 20 to the operating unit 32 when the attachment 30B is abnormal. Therefore, the electrical influence on the tool body 20 due to the abnormality of the attachment 30B can be suppressed.

As described above, in the second modification, the limiting unit 33B melts the thermal fuse 331B by the control circuit 332B. Therefore, the accuracy of the timing of limiting the supply of the power from the tool main body 20 to the operation unit 32 is improved.

2.3 Other Modifications Further, the limiting unit is not limited to the above example. A circuit breaker can also be used as the limiting unit.

Also, the protection circuit 29 of the tool body 20 may include a switch instead of the current fuse 291. That is, the protection circuit 29 may have the same configuration as that of the limiting unit (33, 33A, 33B). However, when the attachment 30 is abnormal, it is preferable that the limiting units (33, 33A, 33B) operate prior to the protection circuit 29. In addition, the tool body 20 may not have the protection circuit 29 as long as the attachment 30 has the limiting portions (33, 33A, 33B).

Also, the attachment 30 may be provided with the second output control unit 26 instead of the tool body 20. In this case, since the attachment connection portion 22 and the main body connection portion 31 need to be provided with terminals for electrically connecting the operation control portion 27 of the tool main body 20 and the second output control portion 26, the attachment connection portion The number of terminals between 22 and the main body connection portion 31 is increased. Therefore, the second output control unit 26 is preferably included in the tool body 20.

Moreover, the electric tool 10 of the said embodiment and modification is what is called a battery drive-type electric tool provided with the battery pack 40. As shown in FIG. However, the power tool 10 may not be a battery-powered power tool. For example, the power tool 10 may obtain power from an external power source such as a commercial AC power source instead of the battery pack 40. In this case, the power supply connection portion 21 of the tool main body 20 may be a plugged cable for connecting to an outlet or a connector to which a cable for connection to an external power supply is connected.

Moreover, the electric tool 10 of the said embodiment and modification is a hammer drill. However, the technical idea of the present disclosure can also be applied to power tools other than hammer drills. Examples of power tools include drivers, drills, wrenches, hammers, nibras, grinders, saws, circular saws, nailing machines.

Moreover, the attachment 30 of the said embodiment and modification is a dust collector. However, the technical idea of the present disclosure can also be applied to attachments other than dust collectors. Examples of attachments include lighting devices, blowers, laser pointers, and laser marking machines.

3. As apparent from the above embodiment and the modification, the power tool (10) of the first aspect comprises a tool body (20) and an attachment (30; 30A) removably attached to the tool body (20); And 30B). The attachment (30; 30A; 30B) has an operation part (32) and a restriction part (33; 33A; 33B). The operating unit (32) is configured to operate with the power supplied from the tool body (20). The limiting unit (33; 33A; 33B) is configured to limit the supply of power from the tool body (20) to the operating unit (32) when the attachment (30; 30A; 30B) is abnormal. . According to the first aspect, the electrical influence on the tool body (20) due to the abnormality of the attachment (30; 30A; 30B) can be suppressed.

The power tool (10) of the second aspect can be realized by combination with the first aspect. In the second aspect, the limiting unit (33) has a current fuse (331) in an electric path for supplying the power supplied from the tool body (20) to the operating unit (32). According to the second aspect, the function of limiting the supply of power from the tool body (20) to the operation unit (32) is realized by the current fuse (331), so the configuration can be simplified and the cost can be reduced. Can be expected.

The power tool (10) of the third aspect can be realized by combination with the second aspect. In a third aspect, the tool body (20) has a current fuse (291) electrically connected in series to the current fuse (331). The rated current value of the current fuse (331) of the limiting portion (33) is smaller than the rated current value of the current fuse (291) of the tool body (20). According to the third aspect, even if the tool body (20) has the current fuse (291), the current fuse (291) of the attachment (30) is melted first. Therefore, even if an abnormality occurs in the attachment (30), the possibility of not replacing the current fuse (291) of the tool body (20) with a new one increases.

The power tool (10) of the fourth aspect can be realized by combination with any one of the first to third aspects. In the fourth aspect, the limiting unit (33A) has a switch (331A) in an electric path for supplying the power supplied from the tool body (20) to the operating unit (32). According to the fourth aspect, unlike the case where a fuse (a current fuse or a thermal fuse) is used to limit the supply of power from the tool body (20) to the operation unit (32), the limiting unit (33A) It can be used again. Therefore, when an abnormality occurs in the attachment (30A), it is not necessary to replace the part (switch 331A) of the limiting unit (33A).

The power tool (10) of the fifth aspect can be realized by combination with the fourth aspect. In the fifth aspect, the restriction unit (33A) controls the switch (331A) when the current flowing to the operation unit (32) exceeds a predetermined value, and the operation unit (32) is controlled from the tool body (20). Control circuit (332A) for limiting the supply of power to According to the fifth aspect, the accuracy of the timing of limiting the supply of power from the tool body (20) to the operation unit (32) is improved.

The power tool (10) of the sixth aspect can be realized by combination with any one of the first to fifth aspects. In a sixth aspect, the limiting unit (33B) includes a thermal fuse (331B) and a control circuit (332B). The thermal fuse (331B) is in an electrical path that supplies the power supplied from the tool body (20) to the operation unit (32). The control circuit (332B) is configured to blow the thermal fuse (331B) when the current flowing through the operation unit (32) exceeds a predetermined value. According to the sixth aspect, the accuracy of the timing of limiting the supply of power from the tool body (20) to the operation unit (32) is improved.

The power tool (10) of the seventh aspect can be realized by combination with any one of the first to sixth aspects. In a seventh aspect, the tool body (20) has a power supply connection (21) to which a battery pack (40) is attached, and is configured to operate with power received by the power supply connection (21). Ru. According to the seventh aspect, there is no need to connect the tool body (20) with the outlet and the cable, and the handleability is improved.

The power tool (10) of the eighth aspect can be realized by a combination with the seventh aspect. In an eighth aspect, the tool body (20) is configured to supply power to the attachment (30; 30A; 30B) based on the power received at the power connection (21). According to the eighth aspect, power can be supplied to the tool body (20) and the attachment (30; 30A; 30B) with one battery pack (40).

The power tool (10) of the ninth aspect can be realized by a combination with the seventh or eighth aspect. In a ninth aspect, the power tool (10) further includes a battery pack (40) removably attached to the power supply connection (21). According to the ninth aspect, there is no need to connect the tool body (20) with an outlet and a cable, and the handleability is improved.

The power tool (10) of the tenth aspect can be realized by combination with any one of the first to ninth aspects. In a tenth aspect, the tool body (20) has an attachment connection (22) having a pair of output terminals (221, 222). The attachment (30; 30A; 30B) has a main body connection portion (31). The main body connection portion (31) has a pair of input terminals (311, 312) electrically connected to the pair of output terminals (221, 222), respectively, and can be removed from the attachment connection portion (22) It is attached. The operation unit (32) is configured to operate by a voltage applied between the pair of input terminals (311, 312). According to the tenth aspect, the number of terminals required to supply power from the tool body (20) to the attachment (30; 30A; 30B) can be reduced. Therefore, an inexpensive connector with a small number of terminals can be used for the attachment connection portion (22) and the main body connection portion (31), and cost reduction can be expected.

The attachment (30; 30A; 30B) of the eleventh aspect is an attachment which is removably attached to the tool body (20) of the power tool (10), and comprises an operation part (32) and a restriction part (33; 33A). 33B). The operating unit (32) is configured to operate with the power supplied from the tool body (20). The limiting unit (33; 33A; 33B) is configured to limit the supply of power from the tool body (20) to the operating unit (32) when the attachment (30; 30A; 30B) is abnormal. . According to the eleventh aspect, the electrical influence on the tool body (20) due to the abnormality of the attachment (30; 30A; 30B) can be suppressed.

DESCRIPTION OF SYMBOLS 10 electric tool 20 tool main body 21 power supply connection part 22

attachment connection part

221, 222 output terminal 291

current fuse

30, 30A, 30B attachment 31 main

body connection part

311, 312 input terminal 32 operation part 321

motor

33, 33A, 33B restriction part 331 Current fuse 331A Switch

331B Thermal fuse

332A, 332B Control circuit 40 Battery pack 41 Main unit connection

Claims

The tool body,
An attachment removably attached to the tool body;
Equipped with
The attachment is
An operating unit operated by power supplied from the tool body;
A limiting unit that limits supply of power from the tool body to the operating unit when the attachment is abnormal;
Have
Electric tool.
The limiting unit has a current fuse in an electrical path that supplies power supplied from the tool body to the operating unit.
The power tool of claim 1.
The tool body has a current fuse electrically connected in series to the current fuse,
The rated current value of the current fuse of the limiting unit is smaller than the rated current value of the current fuse of the tool body,
The power tool of claim 2.
The limiting unit has a switch in an electrical path that supplies power supplied from the tool body to the operating unit.
The power tool according to any one of claims 1 to 3.
The limiting unit has a control circuit that controls the switch to limit supply of power from the tool body to the operating unit when the current flowing to the operating unit exceeds a predetermined value.
The power tool of claim 4.
The restriction unit
A thermal fuse in an electric path for supplying the power supplied from the tool body to the operation unit;
A control circuit which blows the thermal fuse when the current flowing to the operating part exceeds a predetermined value;
Have
An electric power tool according to any one of claims 1 to 5.
The tool body has a power connection to which a battery pack is attached and is configured to operate with power received at the power connection.
The power tool according to any one of claims 1 to 6.
The tool body is configured to supply power to the attachment based on the power received at the power connection.
The power tool of claim 7.
The battery pack further comprises a battery pack removably attached to the power connection,
The power tool according to claim 7 or 8.
The tool body has an attachment connection having a pair of output terminals,
The attachment has a main body connecting portion having a pair of input terminals electrically connected to the pair of output terminals, and detachably mounted on the attachment connecting portion,
The operating unit is configured to operate by a voltage applied between the pair of input terminals,
The power tool according to any one of claims 1 to 9.
An attachment that is removably attached to the tool body of the power tool, the attachment comprising:
An operating unit operated by power supplied from the tool body;
A limiting unit that limits supply of power from the tool body to the operating unit when the attachment is abnormal;
Equipped with
attachment.