WO2021029182A1

WO2021029182A1 - Power tool

Info

Publication number: WO2021029182A1
Application number: PCT/JP2020/027814
Authority: WO
Inventors: 俊哉新戸; 祥和河野; 智明須藤; 勇佑船引; 卓哉天津; 綾香小泉
Original assignee: 工機ホールディングス株式会社
Priority date: 2019-08-09
Filing date: 2020-07-17
Publication date: 2021-02-18
Also published as: JPWO2021029182A1; JP7367763B2

Abstract

Provided is a power tool which does not easily cause a problem in a configuration in which a control unit controls the operation and stop of a motor in response to a signal from a switch. This power tool 1 has: a motor 6; a calculation unit 34 for controlling the motor 6; an operation unit 7 that is movable between an ON position and an OFF position by an operation; and a switch that switches between an ON state and an OFF state by the operation unit 7. The switch has a first signal line LA and a second signal line LB. The calculation unit 34 controls the motor 6 in response to a state of a signal transmitted by the first signal line LA and the second signal line LB.

Description

Power tools

The present invention relates to a power tool in which a control unit controls driving and stopping of a motor by a signal from a switch.

The following Patent Document 1 relates to a power tool. In this power tool, the micro switch is turned on and off by operating the operation unit, a signal from the micro switch is transmitted to the control unit, and the control unit controls driving and stopping of the motor based on the signal. When using a microswitch, it is not a control that performs a momentary operation (an operation that drives the motor when the microswitch is pressed and stops the motor when it is not pressed), but depends on the number of times the microswitch is pressed. It is possible to adopt control (alternate control) that performs so-called alternate operation, which switches between driving and stopping the motor (every time the micro switch is pressed). In alternate control, the driving state of the motor can be maintained even if the hand is released from the operation unit. Therefore, alternate control is suitable for long hours of work.

Japanese Unexamined Patent Publication No. 2017-17769

If a so-called open / close switch is not used, the motor may be rotationally driven when the switching element (inverter circuit) that controls the energization of the motor operates. That is, when the control unit determines that a signal (on signal) for driving the motor is transmitted from the microswitch, the motor may be driven unintentionally. For example, if some noise is added to the signal line connected from the microswitch to the control unit, the control unit may mistakenly recognize this noise as an on signal based on the operation of the operation unit.

In alternate control, for example, when the signal line connected to the control unit from the micro switch is damaged, deformed, or disconnected due to factors such as vibration while the motor is being driven, or when the connection part of the signal line is disconnected, the control unit is connected to the micro switch. It becomes difficult to stop the motor because the signal cannot be sent to.

The present invention has been made in recognition of such a situation, and an object of the present invention is to provide a power tool in which a problem in a configuration in which a control unit controls driving and stopping of a motor by a signal from a switch is unlikely to occur.

One aspect of the present invention is a power tool. This power tool includes a motor, a control unit for controlling the motor, an operation unit that can be moved between an on position and an off position by operation, and a switch that can be switched between an on state and an off state by the operation unit. The switch has a first signal line and a second signal line, and the control unit controls the motor according to the state of the signal transmitted by the first signal line and the second signal line. Control.

In the on state, the switch transmits a first on signal to the control unit by the first signal line and a second on signal to the control unit by the second signal line, and the switch is off. In the state, the first off signal may be transmitted to the control unit by the first signal line, and the second off signal may be transmitted to the control unit by the second signal line.

The control unit may perform alternate control for switching between driving and stopping of the motor each time the first on signal and the second on signal are received.

The operation unit is in the on position while the operation force for moving to the on position is applied, is in the off position when there is no operation force, and the switch is in the on position when the operation unit is in the on position. May be on, and may be off when in the off position.

When the control unit receives the first on signal and the second off signal for a predetermined time, or receives the first off signal and the second on signal for a predetermined time, the control unit starts the motor by the switch. May be regulated.

The control unit receives the first off signal and the second off signal, and receives the first on signal and the second off signal or the first off signal and the second on signal for a predetermined time or longer. When the first off signal and the second off signal are received, the start of the motor by the switch may be restricted.

The switch has an output shaft capable of holding a tip tool, a power transmission unit that converts the rotation of the motor into a reciprocating motion and transmits the power transmission unit to the output shaft, and an accommodation unit that accommodates the power transmission unit. , May be supported by the accommodating portion.

It may have two sets of the operation unit and the switch, and one set and the other set may be provided on one side and the other side of the rotation shaft of the motor, respectively.

The control unit may be able to control the motor by receiving signals from the other set of switches even if one set of switches is in an abnormal state.

It should be noted that any combination of the above components and a conversion of the expression of the present invention between methods, systems and the like are also effective as aspects of the present invention.

According to the present invention, it is possible to provide a power tool in which a problem in a configuration in which a control unit controls driving and stopping of a motor by a signal from a switch is unlikely to occur.

The side view of the power tool 1 which concerns on embodiment of this invention. Side sectional view of the power tool 1. The front view which omitted the base 2 and the housing 3 of a power tool 1. The circuit block diagram of the power tool 1. The circuit diagram of the switch when the micro switch 17 of the power tool 1 is off. The circuit diagram of the switch when the micro switch 17 is pressed halfway. The circuit diagram of the switch when the micro switch 17 is on. Normally (the first signal line LA and the second signal line LB are both non-disconnected) in each of the off, half-pressed, and on states of the microswitch 17, only the first signal line LA is disconnected, and only the second signal line LB is disconnected. The table which shows the level of the 1st output signal SA and the 2nd output signal SB of the switch in each case of both disconnection (the 1st signal line LA and the 2nd signal line LB are both disconnected). Normally (both the first signal line LA and the second signal line LB are not disconnected), only the first signal line LA is disconnected, only the second signal line LB is disconnected, and both disconnections (the first signal line LA and the second signal line LB are disconnected). The table which shows the level transition of the 1st output signal SA and the 2nd output signal SB of the switch with the state transition of the microswitch 17 in each case of (both disconnection). The control flowchart of the first half of the power tool 1. The control flowchart of the latter half of the power tool 1.

In the following, the same or equivalent components, members, etc. shown in the drawings will be designated by the same reference numerals, and redundant description will be omitted as appropriate. The embodiment is not limited to the invention but is an example. Not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

The present embodiment relates to the power tool 1. The power tool 1 is a cordless type jigsaw that operates with the electric power of the battery pack 9. FIG. 1 defines the front-rear and up-down directions of the power tool 1 that are orthogonal to each other. The blade 11 shown in FIG. 2 is omitted in FIG. As shown in FIG. 1, the power tool 1 has a base 2 and a housing 3 provided above the base 2.

The battery pack 9 is detachably connected to the rear end of the housing 3. A motor 6, a deceleration mechanism 5, a reciprocating conversion mechanism 8, and a control board 20 are provided in the housing 3. The housing 3 is, for example, a resin molded body, and a metal case (gear case) 4 as an accommodating portion is provided (fixed) in the front portion of the housing 3. The metal case 4 houses the deceleration mechanism 5 and the reciprocating motion conversion mechanism 8, and also houses a part of the plunger 10 as an output shaft. The deceleration mechanism 5 and the reciprocating motion conversion mechanism 8 correspond to the power transmission unit of the present invention.

The motor 6 is an inner rotor type brushless motor. The rotation of the motor 6 is decelerated by the speed reduction mechanism 5, and is converted into the vertical reciprocating motion of the plunger 10 by the reciprocating motion conversion mechanism 8. A blade 11 as a tip tool that reciprocates up and down together with the plunger 10 is attached to the lower end of the plunger 10. The blade 11 projects downward from the lower surface of the base 2. The rotation shaft of the motor 6 and the plunger 10 share the same position in the left-right direction. Since the configuration and operation from the rotation of the motor 6 to the reciprocating movement of the blade 11 are well known, further detailed description will be omitted.

A sensor substrate 13 is provided behind the motor 6. The sensor board 13 mounts the magnetic sensor 42 shown in FIG. 4 for detecting the rotation position (rotor rotation position) of the motor 6. A speed change dial 12 is provided behind the sensor board 13. The operator can change the rotation speed (rotation speed) of the motor 6 by operating the speed change dial 12. The control board 20 is provided at a position above the battery pack 9. The control board 20 mounts circuit components necessary for drive control of the motor 6.

As shown in FIG. 1, an operation unit 7 is provided on the right side surface of the housing 3. An operation unit 7 having the same configuration and the same function is also provided on the left side surface of the housing 3. The operation unit 7 can slide and move in the front-rear direction by a predetermined distance. In FIG. 1, the operation unit 7 is at the rear end position. The rear end position of the operation unit 7 is the off position, and the front end position is the on position. The operation unit 7 is urged toward the rear end position (off position) side by a urging means such as a spring (not shown). Therefore, when the operator releases the hand, the operation unit 7 automatically returns to the rear end position. The operation unit 7 is provided in front of the handle portion 3a of the housing 3 and at a position where it can be operated by a hand (particularly the thumb) holding the handle portion 3a.

The operation unit 7 can be engaged with the micro switch 17 described later, and the micro switch 17 is in the off state when the operation unit 7 is in the off position, and the micro switch 17 is operated when the operation unit 7 is in the on position. It is pushed by the unit 7 and turned on. The drive and stop of the motor 6 are switched each time the micro switch 17 is turned on (turned on), that is, each time the operation unit 7 is slid forward.

As shown in FIG. 3, one microswitch 17 is provided on each of the left and right sides, and the left and right operation units 7 independently switch on and off the microswitches 17. The micro switch 17 has a plunger 17a and a leaf spring 17b. The plunger 17a is supported by the housing 3 so as to project rearward. The leaf spring 17b can swing back and forth with the lower end as a fulcrum. By sliding the operation unit 7 forward, the operation force is transmitted to the plunger 17a via the leaf spring 17b, and the micro switch 17 is turned on. As shown in FIG. 2, the leaf spring 17b is separated from the plunger 17a when no operating force is applied to the operating unit 7. The operator can switch between driving and stopping the motor 6 by sliding the left or right operation unit 7 forward, that is, by turning on either the left or right micro switch 17. The two microswitches 17 are held in a common holder 16 and are located at substantially the same position as the plunger 10 in the front-rear direction, and are separately located on the left and right sides of the plunger 10. The holder 16 is, for example, a resin molded body, and is attached (fixed) to the metal case 4. That is, the microswitch 17 is supported by the metal case 4. An LED 49 for illuminating the work area is provided on the front portion of the holder 16. The LED 49 is positioned by the holder 16. The holder 16 is a single member that realizes both the positioning of the two microswitches 17 and the positioning of the LED 49.

The connector 14 is for wiring connection and is provided above the motor 6. The wiring 15 having one end connected to the connector 14 includes a wiring extending from each of the two microswitches 17 and a wiring extending from the LED 49. The wiring extending from each of the two microswitches 17 is a total of three wires, two signal lines (first signal line LA and second signal line LB described later) and a ground line. The wiring 15 is connected to each other with the wiring extending from the control board 20 via the connector 14.

FIG. 4 is a circuit block diagram of the power tool 1. The control circuit unit 40 is mounted on the control board 20 shown in FIG. The control circuit unit 40 performs various controls such as drive control of the inverter circuit 43. The inverter circuit 43 as a drive circuit includes switching elements Q1 to Q6 such as IGBTs and FETs connected by a three-phase bridge, and switches according to the control of the control circuit unit 40 to operate the stator coils 6e (U, V) of the motor 6. , W windings) are supplied with drive current.

The temperature detection element 47 is, for example, a thermistor, and is arranged in the vicinity of the switching elements Q1 to Q6. The resistors Rs are provided in the current path of the motor 6. The control circuit voltage supply circuit 46 converts the voltage of the battery pack 9 into a voltage suitable for the operation of the control circuit unit 40 and supplies the voltage to the control circuit unit 40. The magnetic sensor 42 is, for example, a Hall element or a Hall IC, and outputs a signal corresponding to the rotation position of the motor 6 (rotation position of the rotor 6c). The LED light 49 is, for example, a light that irradiates a work material with light, and is turned on under the control of the calculation unit 34 when a light lighting switch (not shown) is turned on. Each of the two notification units 18 is provided corresponding to one micro switch 17, and notifies the operator according to the control of the calculation unit 34 when the corresponding micro switch 17 is abnormal. The notification unit 18 is, for example, an LED that lights up when an abnormality occurs.

In the control circuit unit 40, the motor current detection circuit 37 detects the drive current (load) of the motor 6 by the voltage across the detection resistor Rs and transmits it to the calculation unit 34. The two switch operation detection circuits 38 are provided corresponding to the left and right microswitches 17, respectively. Each switch operation detection circuit 38 transmits on / off of the corresponding microswitch 17, that is, an on signal or an off signal corresponding to the operation of the operation unit 7 by the operator to the calculation unit 34. The set of the micro switch 17 and the switch operation detection circuit 38 corresponds to the switch (switch unit) of the present invention. In this embodiment, two switches having the same configuration and the same function are provided.

The rotor position detection circuit 35 detects the rotation position of the motor 6 based on the signal from the magnetic sensor 42 and transmits it to the calculation unit 34. The motor rotation speed detection circuit 36 detects the rotation speed of the motor 6 based on the signal from the rotor position detection circuit 35 and transmits it to the calculation unit 34. The inverter temperature detection circuit 48 detects the temperatures of the switching elements Q1 to Q6 based on the output voltage of the temperature detection element 47 and transmits them to the calculation unit 34. The calculation unit 34 as a control unit includes a microcontroller and the like, and is a control signal according to a reception signal from the switch operation detection circuit 38, a reception signal from the rotor position detection circuit 35, and a reception signal from the speed change dial 12. The output circuit 45 is driven, and the switching elements Q1 to Q6 of the inverter circuit 43 are switched and controlled.

5 to 7 show circuit diagrams of switches when the plunger 17a is off (position), half-pressed (position), and on (position). When the plunger 17a is in the off, half-pressed, and on states, the entire switch of the microswitch 17 including the plunger 17a is also defined to be in the off, half-pressed, and on states. The micro switch 17 is a one-pole double-throw type (single-pole double-throw type) switch, one end of which is connected to the ground.

The other end of the microswitch 17 is connected to the second signal line LB as shown in FIG. 5 when the microswitch 17 (plunger 17a) is not pressed (in the off state), and the microswitch 17 is pressed. When it is (in the ON state), it is connected to the first signal line LA as shown in FIG. The micro switch 17 is temporarily half-pressed in the process of moving the operation unit 7 shown in FIG. 1 between the off position and the on position. When the other end of the micro switch 17 is in the half-pressed state, it is not connected to either the first signal line LA or the second signal line LB as shown in FIG.

The first signal line LA and the second signal line LB connect the other end of the microswitch 17 to the calculation unit 34 shown in FIG. 4, respectively. The resistor R1 is connected between the power supply line to which the power supply voltage Vcc (for example, 5V) is supplied and the first signal line LA. The resistor R2 is connected between the power supply line and the second signal line LB. The microswitch 17 transmits the first output signal SA to the calculation unit 34 via the first signal line LA, and transmits the second output signal SB to the calculation unit 34 via the second signal line LB.

In the off state shown in FIG. 5, since one end (the end on the microswitch 17 side) of the first signal line LA is open, the first output signal SA of the switch is pulled up by the resistor R1 to a high level (power supply voltage). Vcc). The high level first output signal SA corresponds to the first off signal. On the other hand, in the off state shown in FIG. 5, one end of the second signal line LB is connected to the ground via the micro switch 17, so that the second output signal SB of the switch is at a low level (ground potential). The low level second output signal SB corresponds to the second off signal.

In the half-pressed state shown in FIG. 6, since one end of the first signal line LA is open, the first output signal SA of the switch (microswitch 17) is pulled up by the resistor R1 and is at a high level. Similarly, in the half-pressed state shown in FIG. 6, since one end of the second signal line LB is also open, the second output signal SB of the switch (microswitch 17) is pulled up by the resistor R2 and is at a high level.

In the on state shown in FIG. 7, one end of the first signal line LA is connected to the ground via the micro switch 17, so that the first output signal SA of the switch (micro switch 17) is at a low level. The low-level first output signal SA corresponds to the first on signal. On the other hand, in the on state shown in FIG. 7, since one end of the second signal line LB is open, the second output signal SB of the switch (microswitch 17) is pulled up by the resistor R2 and has a high level. The high level second output signal SB corresponds to the second on signal.

The control of driving and stopping the motor 6 by the calculation unit 34 is alternate control. Specifically, the arithmetic unit 34 is a combination of the first on signal and the second on signal via the first signal line LA and the second signal line LB (low-level first output signal SA and high-level second). Each time a combination of output signals SB) is received, the drive and stop of the motor 6 are switched. Accurate signal transmission may not be possible for the first signal line LA and the second signal line LB due to an abnormality such as breakage, deformation, or disconnection.

When the second signal line LB is disconnected in the off state shown in FIG. 5, the connection of the second signal line LB with the ground is cut off, and the second output signal SB is originally low level, but is pulled up by the resistor R2. It becomes a high level. On the other hand, even if the first signal line LA is disconnected in the off state shown in FIG. 5, the level of the first output signal SA is high and is the same as that in the non-disconnected state.

In the half-pressed state shown in FIG. 6, regardless of which of the first signal line LA and the second signal line LB is disconnected, the levels of the first output signal SA and the second output signal SB are high levels and are the same as when they are not disconnected. ..

When the first signal line LA is disconnected in the on state shown in FIG. 7, the connection of the first signal line LA with the ground is cut off, and the first output signal SA is originally low level, but is pulled up by the resistor R1. It becomes a high level. On the other hand, even if the second signal line LB is disconnected in the on state shown in FIG. 7, the level of the second output signal SB is high and is the same as that in the non-disconnected state.

The levels of the first output signal SA and the second output signal SB according to the state of the microswitch 17 and the states of the first signal line LA and the second signal line LB described above are collectively shown in the table of FIG. .. Further, in the table of FIG. 9, the level transitions of the first output signal SA and the second output signal SB of the switch accompanying the state transition of the microswitch 17 in each state of the first signal line LA and the second signal line LB are shown. Shown together. The calculation unit 34 detects the disconnection of the first signal line LA or the second signal line LB when the combination of the first output signal SA and the second output signal SB received from the microswitch 17 has a predetermined pattern.

The first disconnection detection condition in the calculation unit 34 is to detect a state in which both the first output signal SA and the second output signal SB are at a high level for a first predetermined time, for example, 3 seconds or more. When the second signal line LB is disconnected, both the first output signal SA and the second output signal SB become high levels when the micro switch 17 is in the off state (when the operation unit 7 is in the off position). When the first predetermined time elapses in this state, the first disconnection detection condition is satisfied. When the first disconnection detection condition is satisfied, the calculation unit 34 determines that the second signal line LB is disconnected, stops the motor 6 if the motor 6 is driven, and then turns on the microswitch 17. The start of the motor 6 is regulated by (the motor 6 is not driven).

In the determination of the first disconnection detection condition, it is necessary for the operator to keep the operation unit 7 in a state where both the first output signal SA and the second output signal SB are at a high level for the first predetermined time. To secure a judgment time sufficiently longer than the duration of the half-pressed state of the microswitch 17 (the state in which both the first output signal SA and the second output signal SB are at high levels) when the microswitch 17 is slowly slid forward. Is.

The second disconnection detection condition in the calculation unit 34 is that the first output signal SA is at a high level and the second output signal SB is at a low level, and the first output signal SA and the second output signal SB are both at a high level. It is to detect that the first output signal SA has returned to the high level and the second output signal SB has returned to the low level state after the state has been continued for a second predetermined time, for example, 0.2 seconds. When the first signal line LA is disconnected, even if the micro switch 17 is turned on (even if the operation unit 7 is turned on), the first output signal SA does not become low level, and the first output signal SA and Both the second output signals SB are at a high level. When the operator slides the operation unit 7 forward (turns it on) and releases the operation unit 7 (when the operation unit 7 returns to the off position) while the first signal line LA is disconnected, the second signal line LA is disconnected. The disconnection detection condition of is satisfied. When the second disconnection detection condition is satisfied, the calculation unit 34 determines that the first signal line LA is disconnected, stops the motor 6 if the motor 6 is driven, and then turns on the microswitch 17. The start of the motor 6 is regulated by.

In the determination of the second disconnection detection condition, it is necessary that the state where both the first output signal SA and the second output signal SB are at a high level continues for the second predetermined time due to vibration or erroneous operation (operation unit 7). When the operation unit 7 slides forward to the extent that the micro switch 17 does not turn on due to a sudden touch, etc., and a state transition of off, half-press, or off occurs on the micro switch 17, a disconnection is detected by mistake. This is because it does not. The second predetermined time is set shorter than the first predetermined time. This is because the determination time is short so that the disconnection can be detected even when the operator quickly slides the operation unit 7 forward and releases the hand.

The control flow of the power tool 1 will be described with reference to FIGS. 10 and 11. The variables, SW_STATE, SW_STATE_OLD, and SW_STATE_OLD2, which appear in FIGS. 10 and 11, are variables for storing the state of the microswitch 17, that is, the combination of the levels of the first output signal SA and the second output signal SB, respectively. The latest three types of states of the microswitch 17 are stored in SW_STATE, SW_STATE_OLD, and SW_STATE_OLD2 in order from the newest one.

The calculation unit 34 is in a state where the micro switch 17 is not pressed (a state in which the first output signal SA is at a high level and the second output signal SB is at a low level) continues for a predetermined time (Yes in S1 and Yes in S2). ), The state in which the microswitch 17 is pressed (the state in which the first output signal SA is at a low level and the second output signal SB is at a high level) continues for a predetermined time (Yes in S3, Yes in S4), and , SW_STATE, SW_STATE_OLD, and SW_STATE_OLD2 are updated (S7 to S9) when the state where both the first output signal SA and the second output signal SB are at high levels continues for a predetermined time (Yes in S5, Yes in S6). .. To update SW_STATE, SW_STATE_OLD, and SW_STATE_OLD2, specifically, the value of SW_STATE_OLD is assigned to SW_STATE_OLD2 (S7), the value of SW_STATE is assigned to SW_STATE_OLD (S8), and the current first output signal SA and second are assigned to SW_STATE. Substituting the combination of the levels of the output signal SB (S9).

The predetermined time in step S2, that is, the determination time (off determination time) that the microswitch 17 is not pressed (off state) is set to, for example, 50 ms so that the influence of noise or the like can be removed. The predetermined time in step S4, that is, the determination time (on determination time) that the microswitch 17 is pressed (on state) is whether the motor 6 is turned off or turned on (the motor 6 is currently being driven). It depends on whether it is stopped or not. If the next is the turn-off of the motor 6 (if the motor 6 is currently being driven), the on determination time is set to, for example, 50 ms so that the influence of noise or the like can be eliminated. On the other hand, if the next time the motor 6 is turned on (if the motor 6 is currently stopped), the on determination time is a momentary microswitch due to vibration or erroneous operation (such as when the operation unit 7 is suddenly touched). For example, 200 ms longer than 50 ms so as to ignore the 17 on. The reason why the on-determination times are different in this way is to increase the reaction and certainty to the stop operation of the motor 6 while suppressing the risk of the motor 6 starting unexpectedly.

In the calculation unit 34, the combination in which SW_STATE_OLD corresponds to the off of the micro switch 17, that is, the combination of the first off signal and the second off signal (combination of the high level first output signal SA and the low level second output signal SB). And SW_STATE corresponds to the on of the microswitch 17, that is, the combination of the first on signal and the second on signal (combination of the low level first output signal SA and the high level second output signal SB). In a certain case (Yes in S11), the drive / stop of the motor 6 is switched (S13), and the process returns to the start. Yes in step S11 means that the operator quickly slides the operation unit 7 forward and half-presses the microswitch 17 (both the first output signal SA and the second output signal SB are at a high level). This is the case where it does not continue for 200 ms or more.

In the case of No in step S11, the calculation unit 34 is a combination in which SW_STATE_OLD is a combination of the high-level first output signal SA and the high-level second output signal SB, and SW_STATE corresponds to the on of the microswitch 17. That is, in the case of a combination of the first on signal and the second on signal (combination of the low level first output signal SA and the high level second output signal SB) (Yes in S12), the drive / stop of the motor 6 is switched. (S13), return to the start. Yes in step S12 is a state in which the operator slowly slides the operation unit 7 forward and half-presses the micro switch 17 (a state in which both the first output signal SA and the second output signal SB are at a high level). Is the case where is continued for 200 ms or more.

In the case of No in step S12, the calculation unit 34 has a combination in which SW_STATE_OLD2 corresponds to the off of the microswitch 17, that is, a combination of the first off signal and the second off signal (high-level first output signal SA and low-level combination). (Combination of second output signal SB), where SW_STATE_OLD is a combination of high-level first output signal SA and high-level second output signal SB, and SW_STATE is a combination corresponding to the off of the microswitch 17. (Yes in S14), it is determined that the wire is broken (S17). Yes in step S14 is when the operator slides the operation unit 7 forward and releases the hand while the first signal line LA is disconnected and the second signal line LB is not disconnected. is there.

In the case of No in step S14, the calculation unit 34 is a combination of the first output signal SA having a high SW_STATE and the second output signal SB having a high level (Yes in S15), and the state is a predetermined time, for example, 3. If it continues for a second (Yes in S16), it is determined that the wire is broken (S17). Yes in step S16 is when at least the second signal line LB is disconnected.

When the calculation unit 34 determines that the wire is disconnected, the motor 6 is stopped if the motor 6 is being driven, and thereafter, the start of the motor 6 by turning on the microswitch 17 belonging to the switch that caused the disconnection is restricted. However, the start of the motor 6 by turning on the micro switch 17 belonging to the other switch is not regulated. When the calculation unit 34 determines that the wire is broken, the calculation unit 34 notifies the operator by the notification unit 18 corresponding to the micro switch 17 belonging to the switch that caused the disconnection.

According to this embodiment, the following effects can be obtained.

(1) Since there are two signal lines connecting the micro switch 17 and the calculation unit 34, the first signal line LA and the second signal line LB, the micro switch is compared with the case where there is only one signal line. The state of 17 can be detected more accurately by the calculation unit 34.

(2) Since there are two signal lines as described above, malfunction can be suppressed even if noise is on one of them. Here, since the two signal lines have a configuration in which complementary outputs (if one is a high level, the other is a low level output), malfunction can be suitably suppressed even when the same noise rides on the two lines. ..

(3) Since two signal lines are passed from one microswitch 17 to the calculation unit 34, compared with the case where one signal line is passed from each to the calculation unit 34 using two microswitches, It does not take up space and is easy to assemble.

(4) The calculation unit 34 can perform more complicated control based on the signal transmitted from the microswitch 17 via the two signal lines.

(5) The arithmetic unit 34 executes alternate control for switching between driving and stopping of the motor 6 each time the micro switch 17 is turned on, that is, each time the operation unit 7 is slid forward. Does not need to keep the operation unit 7 in the on position, and has good operability and workability. In addition, an on-lock mechanism is not required, and the configuration can be simplified.

(6) Since the calculation unit 34 determines that the first output signal SA and the second output signal SB are both at a high level for the first predetermined time, for example, 3 seconds or more, the disconnection is determined, so that the second signal line LB The disconnection can be suitably detected.

(7) The calculation unit 34 sets a state in which the first output signal SA is at a high level and the second output signal SB is at a low level, and a state in which both the first output signal SA and the second output signal SB are at a high level. After continuing for a predetermined time, for example, 0.2 seconds, when the first output signal SA returns to the high level state and the second output signal SB returns to the low level state, it is determined that the wire is broken. Therefore, the first signal line LA is preferably broken. Can be detected.

(8) Due to the configuration for detecting disconnection as described above, the microswitch 17 can be attached to the metal case 4 in which strong vibration in the reciprocating direction is generated via the holder 16.

(9) The set of the micro switch 17 and the operation unit 7 engaged with the micro switch 17 is provided separately on the left and right sides of the rotation shaft of the motor 6, and the operator drives and stops the motor 6 regardless of which operation unit 7 is operated. Operability and workability are good because it can be switched. The risk of malfunction increases by providing two sets of the micro switch 17 and the operation unit 7, but the risk of malfunction can be preferably reduced by using two signal lines connecting the micro switch 17 and the calculation unit 34 as described above. Can be suppressed. Further, even if an abnormality such as a disconnection occurs in one set of microswitches 17, the motor 6 can be switched between driving and stopping by the other set, and the work can be continued.

Although the present invention has been described above by taking the embodiment as an example, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, a modification will be described.

The power tool of the present invention may be of a type other than a jigsaw, or may be a corded type that operates with power supplied from an external AC power source. The motor may be a brushed motor. The time shown in the embodiment is an example, and may be changed as appropriate. The voltage level (high or low) shown in the embodiment may be inverted as appropriate. The number of switches may be one or three or more.

1 ... Power tool, 2 ... Base, 3 ... Housing, 3a ... Handle part, 4 ... Metal case (gear case), 5 ... Reduction mechanism, 6 ... Motor, 7 ... Operation part, 9 ... Battery pack, 10 ... Plunger (output) Axis), 11 ... Blade (tip tool), 12 ... Shift dial, 13 ... Sensor board, 14 ... Connector, 15 ... Wiring, 16 ... Holder, 17 ... Microswitch, 18 ... Notification unit, 20 ... Control board, 34 ... Calculation unit (control unit), 40 ... control circuit unit, 43 ... inverter circuit, 49 ... LED

Claims

With the motor
A control unit for controlling the motor and
An operation unit that can be moved to the on position and off position by operation,
It has a switch that can be switched between an on state and an off state by the operation unit.
The switch has a first signal line and a second signal line.
The control unit is a power tool that controls the motor according to the state of signals transmitted by the first signal line and the second signal line.
In the on state, the switch transmits the first on signal to the control unit by the first signal line, and transmits the second on signal to the control unit by the second signal line.
The first aspect of the present invention, wherein the switch transmits a first off signal to the control unit by the first signal line and a second off signal to the control unit by the second signal line in the off state. Power tools.
The power tool according to claim 2, wherein the control unit performs alternate control for switching between driving and stopping of the motor each time the first on signal and the second on signal are received.
The operation unit is in the on position while the operation force for moving to the on position is applied, and is in the off position when there is no operation force.
The power tool according to claim 3, wherein the switch is in an on state when the operation unit is in the on position and in an off state when the operation unit is in the off position.
When the control unit receives the first on signal and the second off signal for a predetermined time, or receives the first off signal and the second on signal for a predetermined time, the control unit starts the motor by the switch. The power tool according to any one of claims 2 to 4, which regulates.
The control unit receives the first off signal and the second off signal, and receives the first on signal and the second off signal or the first off signal and the second on signal for a predetermined time or longer. The power tool according to any one of claims 2 to 5, which regulates the start of the motor by the switch when the first off signal and the second off signal are received.
An output shaft that can hold a tip tool and
A power transmission unit that converts the rotation of the motor into reciprocating motion and transmits it to the output shaft.
It has an accommodating portion for accommodating the power transmission unit and
The power tool according to claim 5 or 6, wherein the switch is supported by the housing portion.
The invention according to any one of claims 5 to 7, wherein the operation unit and the switch are provided in two sets, one set and the other set provided on one side and the other side of the rotation shaft of the motor, respectively. Power tools.
The power tool according to claim 8, wherein the control unit can control the motor by a received signal from the other set of switches even if one set of switches is in an abnormal state.
The switch has a plunger that is pressed by the operation unit, and switches the state of a signal transmitted by the first signal line and the second signal line according to the position of the plunger, according to claims 1 to 9. The power tool according to any one item.