JP7367763B2 - power tools - Google Patents

Description

The present invention relates to a power tool in which a control section controls driving and stopping of a motor based on signals from a switch.

Patent Document 1 below relates to a power tool. In this power tool, a microswitch is turned on and off by operating the operating section, a signal from the microswitch is transmitted to a control section, and the control section controls driving and stopping of the motor based on the signal. When using a microswitch, control is not controlled by momentary operation (driving the motor when the microswitch is pressed and stopping the motor when it is not pressed), but by controlling the number of times the microswitch is pressed. Control (alternate control) that performs so-called alternate operation, in which the motor is switched between driving and stopping (every time a microswitch is pressed), can be adopted. Alternate control allows the motor to maintain its driving state even if you remove your hand from the operating section. Therefore, alternate control is suitable for long-time work.

Japanese Patent Application Publication No. 2017-17769

If a so-called open/close type switch is not used, the motor may be driven to rotate when a switching element (inverter circuit) that controls energization to the motor operates. That is, if the control unit determines that a signal (on signal) for driving the motor has been transmitted from the microswitch, the motor may be driven unintentionally. For example, if some noise is introduced into the signal line leading from the microswitch to the control section, the control section may misinterpret this noise as an on signal based on the operation of the operating section.

With alternate control, for example, if the signal line from the microswitch to the control unit is damaged, deformed, or disconnected due to factors such as vibration while the motor is driving, or if the connection part of the signal line becomes disconnected, the signal line from the microswitch to the control unit This makes it difficult to stop the motor.

The present invention was made in recognition of this situation, and its purpose is to provide a power tool in which problems are unlikely to occur in a configuration in which a control section controls driving and stopping of a motor based on signals from a switch.

An embodiment of the present invention is a power tool. This power tool is
motor and
A switch that can be turned on and off by operator operation;
a first signal line connected to the switch and outputting a first signal indicating that the switch is in the on state or the off state;
a second signal line connected to the switch and outputting a second signal indicating that the switch is in the on state or the off state;
The motor is controlled in either a driving state in which the motor is driven or a stopped state in which driving of the motor is stopped, and when the switch is switched from the off state to the on state, the driving state of the motor is changed. a control unit that switches between the stopped state and the stopped state;
has
The first signal includes a first on signal and a first off signal,
The second signal includes a second on signal and a second off signal,
In the on state, the switch transmits the first on signal to the control unit through the first signal line, and transmits the second on signal to the control unit through the second signal line,
In the off state, the switch transmits the first off signal to the control unit through the first signal line, and transmits the second off signal to the control unit through the second signal line,
The control unit is configured to switch the motor between the drive state and the stop state when both the first on signal and the second on signal are detected,
The control unit is configured to cause the switch to control when the first on signal and the second off signal are received for a first time, or when the first off signal and the second on signal are received for a first time. regulating starting of the motor;
Further, the control unit receives the first off signal and the second off signal, and then converts the first on signal and the second off signal or the first off signal and the second on signal into a second on signal. regulating the starting of the motor by the switch when the first off signal and the second off signal are received for a period of time or more;
The second time is set shorter than the first time.

The control unit may be configured to restrict starting of the motor when the first signal line is disconnected, and also to restrict starting of the motor when the second signal line is disconnected.

an operation section for switching the switch between the on state and the off state by an operation of a worker;
The operating portion is in the on position while an operating force is applied to move it to the on position, and is in the off position when no operating force is applied,
The switch may be in an on state when the operating portion is in the on position, and may be in an off state when the operating portion is in the off position.

The switch includes an output shaft that can hold a tip tool, a power transmission section that converts rotation of the motor into reciprocating motion and transmits it to the output shaft, and a housing section that houses the power transmission section. , may be supported by the accommodating portion.

There may be two sets of the operating section and the switch, and one set and the other set may be provided on one side and the other side, respectively, with the rotating shaft of the motor interposed therebetween.

The control unit may be able to control the motor based on a signal received from the other set of switches even if one set of switches is in an abnormal state.

Note that arbitrary combinations of the above components and expressions of the present invention converted between methods, systems, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to provide a power tool in which problems are unlikely to occur in a configuration in which a control section controls driving and stopping of a motor based on a signal from a switch.

1 is a side view of a power tool 1 according to an embodiment of the present invention. FIG. 1 is a side sectional view of the power tool 1. FIG. FIG. 2 is a front view of the power tool 1 with the base 2 and housing 3 omitted. FIG. 2 is a circuit block diagram of the power tool 1. The circuit diagram of the switch when the microswitch 17 of the power tool 1 is off. The circuit diagram of the switch when the microswitch 17 is pressed halfway. The circuit diagram of the switch when the microswitch 17 is on. Normally (both the first signal line LA and second signal line LB are not disconnected), only the first signal line LA is disconnected, only the second signal line LB is disconnected, in the off, half-pressed, and on states of the microswitch 17. A table showing the levels of the first output signal SA and the second output signal SB of the switch in each case of both wire breaks (both the first signal line LA and the second signal line LB are broken). 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 are disconnected (the first signal line LA and the second signal line LB are disconnected) 3 is a table showing the level transitions of the first output signal SA and the second output signal SB of the switch in accordance with the state transition of the microswitch 17 in each case (both wires are disconnected). A control flowchart for the first half of the power tool 1. 5 is a control flowchart of the second half of the power tool 1.

In the following, the same or equivalent components, members, etc. shown in each drawing are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. The embodiments are illustrative rather than limiting. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

This embodiment relates to a power tool 1. The power tool 1 is a cordless type jigsaw that operates using electric power from a battery pack 9. FIG. 1 defines mutually orthogonal front-rear, upper-lower directions of the power tool 1. Note that the blade 11 shown in FIG. 2 is omitted in FIG. 1. As shown in FIG. 1, the power tool 1 includes a base 2 and a housing 3 provided above the base 2.

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

The motor 6 is an inner rotor type brushless motor. The rotation of the motor 6 is decelerated by the deceleration mechanism 5, and converted into an up and down 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 protrudes downward from the lower surface of the base 2. The rotation shaft of the motor 6 and the plunger 10 have the same horizontal position. 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 explanation will be omitted.

A sensor board 13 is provided behind the motor 6. The sensor board 13 is equipped with a magnetic sensor 42 shown in FIG. 4 for detecting the rotational position of the motor 6 (rotor rotational position). A speed change dial 12 is provided behind the sensor board 13. The operator can change the number of rotations (rotational 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 is equipped with circuit components necessary for drive control of the motor 6.

As shown in FIG. 1, an operating section 7 is provided on the right side of the housing 3. An operating section 7 having the same configuration and function is also provided on the left side surface of the housing 3. The operating portion 7 can be slid forward and backward by a predetermined distance. In FIG. 1, the operating section 7 is at the rear end position. The rear end position of the operating section 7 is an off position, and the front end position is an on position. The operating portion 7 is biased toward the rear end position (off position) by a biasing means such as a spring (not shown). Therefore, when the operator releases his/her hand, the operating section 7 automatically returns to the rear end position. The operating portion 7 is provided in front of the handle portion 3a of the housing 3 and at a position where it can be operated by the hand (particularly the thumb) gripping the handle portion 3a.

The operating section 7 can be engaged with a microswitch 17, which will be described later. When the operating section 7 is in the off position, the microswitch 17 is in the off state, and when the operating section 7 is in the on position, the microswitch 17 is in the off state. It is pressed by part 7 and turns on. Each time the microswitch 17 is turned on (turned on), that is, each time the operating section 7 is slid forward, the motor 6 is switched between driving and stopping.

As shown in FIG. 3, one microswitch 17 is provided on each side, and the microswitches 17 are turned on and off independently of each other by the left and right operation sections 7. The microswitch 17 has a plunger 17a and a leaf spring 17b. The plunger 17a is supported by the housing 3 so as to protrude rearward. The leaf spring 17b can swing back and forth using its lower end as a fulcrum. By sliding the operating portion 7 forward, operating force is transmitted to the plunger 17a via the leaf spring 17b, and the microswitch 17 is turned on. As shown in FIG. 2, when no operating force is applied to the operating section 7, the leaf spring 17b is spaced apart from the plunger 17a. The operator can drive or stop the motor 6 by sliding either the left or right operating section 7 forward, that is, by turning on either the left or right microswitch 17. The two microswitches 17 are held by a common holder 16, are located at approximately the same position as the plunger 10 in the front-rear direction, and are located separately 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 is provided at the front of the holder 16 to illuminate the work area. 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 whose one end is connected to the connector 14 includes wiring extending from each of the two microswitches 17 and wiring extending from the LED 49. There are a total of three wiring lines extending from the two microswitches 17, including two signal lines (first signal line LA and second signal line LB, which will be described later) and a ground line. The wiring 15 is connected to 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 in a three-phase bridge, and performs a switching operation under the control of the control circuit section 40 to control the stator coils 6e (U, V) of the motor 6. , W).

The temperature detection element 47 is, for example, a thermistor, and is arranged near the switching elements Q1 to Q6. A resistor Rs is 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 section 40 and supplies the voltage to the control circuit section 40 . The magnetic sensor 42 is, for example, a Hall element or a Hall IC, and outputs a signal according to the rotational position of the motor 6 (rotational position of the rotor 6c). The LED light 49 is, for example, a light that irradiates a workpiece with light, and is turned on under the control of the calculation unit 34 when a light switch (not shown) is turned on. The two notification units 18 are each provided corresponding to one microswitch 17, and notify the operator under the control of the calculation unit 34 when the corresponding microswitch 17 is abnormal. The notification unit 18 is, for example, an LED that lights up when an abnormality occurs.

In the control circuit section 40 , the motor current detection circuit 37 detects the drive current (load) of the motor 6 based on the voltage across the detection resistor Rs, and transmits it to the calculation section 34 . Two switch operation detection circuits 38 are provided corresponding to the left and right microswitches 17, respectively. Each switch operation detection circuit 38 transmits an on signal or an off signal to the calculation section 34 in accordance with the on/off of the corresponding microswitch 17, that is, the operation of the operating section 7 by the operator. The set of the microswitch 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 function are provided.

The rotor position detection circuit 35 detects the rotational 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 section 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 the detected temperature to the calculation unit 34. The calculation unit 34 as a control unit includes a microcontroller and the like, and generates control signals according to the received signal from the switch operation detection circuit 38, the received signal from the rotor position detection circuit 35, and the received signal from the speed change dial 12. The output circuit 45 is driven to control the switching of the switching elements Q1 to Q6 of the inverter circuit 43.

5 to 7 show circuit diagrams of the switch when the plunger 17a is in the off (position), half-pressed (position), and on (position). Note that when the plunger 17a is in each of the off, half-pressed, and on states, the entire switch of the microswitch 17, including the plunger 17a, is also defined to be in each of the off, half-pressed, and on states. The microswitch 17 is a single-pole double-throw switch, and one end thereof is connected to 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 when the microswitch 17 is pressed When the signal is on (in the on state), it is connected to the first signal line LA as shown in FIG. During the process in which the operating section 7 shown in FIG. 1 moves between the off position and the on position, the microswitch 17 is temporarily pressed halfway. When the microswitch 17 is in the half-pressed state, the other end of the microswitch 17 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 each connect the other end of the microswitch 17 and the calculation section 34 shown in FIG. 4. The resistor R1 is connected between a power supply line to which a power supply voltage Vcc (for example, 5V) is supplied and the first signal line LA. A 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 section 34 via the first signal line LA, and transmits the second output signal SB to the calculation section 34 via the second signal line LB.

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

In the half-pressed state shown in FIG. 6, one end of the first signal line LA is open, so 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, one end of the second signal line LB is also open, so 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 microswitch 17, so the first output signal SA of the switch (microswitch 17) is at a low level. The first output signal SA at low level corresponds to the first on signal. On the other hand, in the on state shown in FIG. 7, one end of the second signal line LB is open, so the second output signal SB of the switch (microswitch 17) is pulled up by the resistor R2 and is at a high level. The second output signal SB at a high level corresponds to the second on signal.

Control of driving and stopping of the motor 6 by the calculation unit 34 is alternate control. Specifically, the calculation unit 34 generates a combination of the first on signal and the second on signal (the first output signal SA at a low level and the second output signal at a high level) via the first signal line LA and the second signal line LB. Each time a combination of output signals SB (combination of output signals SB) is received, driving and stopping of the motor 6 is switched. The first signal line LA and the second signal line LB may not be able to accurately transmit signals due to abnormalities such as damage, deformation, or disconnection.

If the second signal line LB is disconnected in the off state shown in FIG. 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 level, which is the same as when the line is not disconnected.

In the half-pressed state shown in FIG. 6, even if either the first signal line LA or the second signal line LB is disconnected, the levels of the first output signal SA and the second output signal SB are high level and remain the same as when there is no disconnection. .

If the first signal line LA is disconnected in the on state shown in FIG. 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 remains high and remains the same as when the line is not disconnected.

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 second signal line LB, which have been explained above, are collectively shown in the table of FIG. . The table in FIG. 9 also shows the level transitions of the first output signal SA and second output signal SB of the switch due to the state transition of the microswitch 17 in each state of the first signal line LA and the second signal line LB. Shown together. The calculation unit 34 detects a 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 forms 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 period of 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 level when the microswitch 17 is in the off state (when the operating section 7 is in the off position). When the first predetermined time period 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 it is being driven, and thereafter turns on the microswitch 17. (the motor 6 is not driven).

In determining the first disconnection detection condition, it is necessary that the first output signal SA and the second output signal SB both remain at a high level for a first predetermined period of time. To ensure a sufficiently longer determination time 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 level) when the microswitch 17 is slowly slid forward. It is.

The second disconnection detection condition in the calculation unit 34 is that the first output signal SA and the second output signal SB are both high level from the state where the first output signal SA is high level and the second output signal SB is low level. After the state continues for a second predetermined time, for example, 0.2 seconds, it is detected that the first output signal SA has returned to a high level and the second output signal SB has returned to a low level. If the first signal line LA is disconnected, even if the microswitch 17 is turned on (even if the operating section 7 is turned on), the first output signal SA will not go to low level, and the first output signal SA and Both second output signals SB become high level. When the operator slides the operating section 7 forward (turns it to the on position) and releases the operating section 7 with the first signal line LA disconnected (when the operating section 7 returns to the off position), the second signal line LA is disconnected. The disconnection detection conditions are met. 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 being driven, and thereafter turns on the microswitch 17. The starting of the motor 6 due to

In determining the second disconnection detection condition, it is necessary that both the first output signal SA and the second output signal SB remain at a high level for a second predetermined period of time. If the operating unit 7 slides forward to the extent that the microswitch 17 does not turn on due to unexpected hand contact, etc., and the state transition of the microswitch 17 from OFF to half-press to OFF occurs, a disconnection will be detected incorrectly. This is to avoid doing so. The second predetermined time is set shorter than the first predetermined time. This is to ensure a short determination time so that disconnection can be detected even when the operator quickly slides the operating section 7 forward and releases his/her hand.

The flow of control of the power tool 1 will be explained with reference to FIGS. 10 and 11. The variables SW_STATE, SW_STATE_OLD, and SW_STATE_OLD2 appearing 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 three most recent states of the microswitch 17 are stored in SW_STATE, SW_STATE_OLD, and SW_STATE_OLD2 in order from newest to newest.

When the state in which the microswitch 17 is not pressed (the state in which the first output signal SA is at high level and the second output signal SB is at low level) continues for a predetermined period of time (Yes in S1, Yes in S2), ), when the state in which the microswitch 17 is pressed (the state in which the first output signal SA is at low level and the second output signal SB is at high level) continues for a predetermined time (Yes in S3, Yes in S4), and , when both the first output signal SA and the second output signal SB remain at high level for a predetermined period of time (Yes in S5, Yes in S6), update SW_STATE, SW_STATE_OLD, and SW_STATE_OLD2 (S7 to S9). . Specifically, updating of SW_STATE, SW_STATE_OLD, and SW_STATE_OLD2 involves assigning the value of SW_STATE_OLD to SW_STATE_OLD2 (S7), assigning the value of SW_STATE to SW_STATE_OLD (S8), and assigning the current first output signal SA and second output signal to SW_STATE. This involves substituting the combination of levels of the output signal SB (S9).

The predetermined time in step S2, that is, the time for determining that the microswitch 17 is not pressed (off state) (off determination time) is set to, for example, 50 ms so as to eliminate the influence of noise and the like. The predetermined time in step S4, that is, the time for determining whether the microswitch 17 is pressed (being in the on state) (on determination time) is the time for determining whether the motor 6 is next turned off or turned on (whether the motor 6 is currently being driven or not). It depends on whether it is stopped or not. If the next time is to turn off the motor 6 (if the motor 6 is currently being driven), the on-determination time is set to, for example, 50 ms so as to eliminate the influence of noise and the like. On the other hand, if the next time is to turn on the motor 6 (if the motor 6 is currently stopped), the on-determination time will be determined by the momentary microswitch caused by vibration or erroneous operation (such as a sudden hand hitting the operating section 7). The time period is set to be longer than 50 ms, for example, 200 ms, so as to ignore the ON of 17. The reason why the on-determination times are made different in this way is to suppress the risk of the motor 6 starting unexpectedly, and to increase the response and reliability to the operation to stop the motor 6.

The calculation unit 34 calculates a combination in which SW_STATE_OLD corresponds to the off state of the microswitch 17, that is, a combination of the first off signal and the second off signal (a combination of the first output signal SA at a high level and the second output signal SB at a low level). and SW_STATE is a combination corresponding to turning on the microswitch 17, that is, a combination of the first on signal and the second on signal (a combination of the first output signal SA at a low level and the second output signal SB at a high level). If yes (Yes in S11), the motor 6 is switched between driving and stopping (S13), and the process returns to the start. The answer in step S11 is Yes when the operator quickly slides the operation unit 7 forward and presses the microswitch 17 halfway (the state where both the first output signal SA and the second output signal SB are at high level). This is a case where the duration does not continue for 200ms or more.

In the case of No in step S11, the calculation unit 34 calculates a combination in which SW_STATE_OLD is a combination of a high level first output signal SA and a high level second output signal SB, and SW_STATE corresponds to turning on the microswitch 17; In other words, if the combination of the first on signal and the second on signal (the combination of the first output signal SA at low level and the second output signal SB at high level) (Yes in S12), the motor 6 is switched between driving and stopping. (S13) Return to the start. Yes in step S12 means that the operator slowly slides the operation unit 7 forward and presses the microswitch 17 halfway (a state in which both the first output signal SA and the second output signal SB are at high level). This is a case where the period continues for 200ms or more.

In the case of No in step S12, the calculation unit 34 determines that SW_STATE_OLD2 is a combination corresponding to the off state of the microswitch 17, that is, a combination of the first off signal and the second off signal (the first output signal SA at a high level and the first output signal SA at a low level). (combination of the second output signal SB), SW_STATE_OLD is a combination of the first output signal SA at high level and the second output signal SB at high level, and SW_STATE is a combination corresponding to turning off the microswitch 17. (Yes in S14), it is determined that the wire is disconnected (S17). Yes in step S14 occurs when the operator slides the operating unit 7 forward and releases it while the first signal line LA is disconnected and the second signal line LB is not disconnected. be.

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

If the calculation unit 34 determines that the wire is broken, it stops the motor 6 if it is being driven, and thereafter restricts starting of the motor 6 by turning on the microswitch 17 belonging to the switch that caused the wire breakage. However, starting of the motor 6 by turning on the microswitch 17 belonging to the other switch is not restricted. If the calculation unit 34 determines that a wire is broken, it notifies the operator using the notification unit 18 that corresponds to the microswitch 17 that belongs to the switch that caused the wire breakage.

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

(1) Since there are two signal lines, the first signal line LA and the second signal line LB, that connect the microswitch 17 and the calculation unit 34, the microswitch 17 can be detected more accurately by the arithmetic unit 34.

(2) As mentioned above, since there are two signal lines, malfunctions can be suppressed even if noise is applied to one of the lines. Here, since the two signal lines are configured to output complementary outputs (one outputs at a high level, the other outputs a low level), malfunctions can be suitably suppressed even if the same noise is on the two lines. .

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

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

(5) The calculation unit 34 executes alternate control that switches between driving and stopping the motor 6 each time the microswitch 17 is turned on, that is, each time the operation unit 7 is slid forward. It is not necessary to maintain the operation part 7 in the on position, and the operability and workability are good. Further, an on-lock mechanism is not required, and the configuration can be simplified.

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

(7) The calculation unit 34 changes the state from the state where the first output signal SA is high level and the second output signal SB is low level to the state where both the first output signal SA and the second output signal SB are high level. If the first output signal SA returns to a high level and the second output signal SB returns to a low level after a predetermined period of time, for example 0.2 seconds, it is determined that the first signal line LA is disconnected. Can be detected.

(8) Since the configuration detects disconnection as described above, the microswitch 17 can be attached via the holder 16 to the metal case 4 where strong vibrations in the reciprocating direction occur.

(9) A set of microswitches 17 and operating sections 7 that engage with them are provided separately on the left and right sides of the rotating shaft of the motor 6, so that the operator can drive or stop the motor 6 by operating either operating section 7. It has good operability and workability because it can be switched. Although the risk of malfunction increases by providing two sets of the microswitch 17 and the operation section 7, the risk of malfunction can be reduced by using two signal lines connecting the microswitch 17 and the calculation section 34 as described above. It can be suppressed. Furthermore, even if an abnormality such as a wire breakage occurs in one set of microswitches 17, the motor 6 can be switched between driving and stopping using the other set, and work can be continued.

Although the present invention has been described above using the embodiments as examples, those skilled in the art will understand that various modifications can be made to each component and each processing process of the embodiments within the scope of the claims. By the way. Modifications will be discussed below.

The power tool of the present invention may be of a type other than a jigsaw, or may be of a corded type that operates with power supplied from an external AC power source. The motor may be a brushed motor. The times shown in the embodiments are merely examples, and may be changed as appropriate. The voltage levels (high or low) shown in the embodiments may be reversed as appropriate. There may be one or more switches.

DESCRIPTION OF SYMBOLS 1...Power tool, 2...Base, 3...Housing, 3a...Handle part, 4...Metal case (gear case), 5...Reduction mechanism, 6...Motor, 7...Operation unit, 9...Battery pack, 10...Plunger (output) shaft), 11...blade (tip tool), 12...speed dial, 13...sensor board, 14...connector, 15...wiring, 16...holder, 17...micro switch, 18...notification unit, 20...control board, 34... Arithmetic unit (control unit), 40... Control circuit unit, 43... Inverter circuit, 49... LED

Claims (10)

motor and
A switch that can be turned on and off by operator operation;
a first signal line connected to the switch and outputting a first signal indicating that the switch is in the on state or the off state;
a second signal line connected to the switch and outputting a second signal indicating that the switch is in the on state or the off state;
The motor is controlled in either a driving state in which the motor is driven or a stopped state in which driving of the motor is stopped, and when the switch is switched from the off state to the on state, the driving state of the motor is changed. a control unit that switches between the stopped state and the stopped state;
has
The first signal includes a first on signal and a first off signal,
The second signal includes a second on signal and a second off signal,
In the on state, the switch transmits the first on signal to the control unit through the first signal line, and transmits the second on signal to the control unit through the second signal line,
In the off state, the switch transmits the first off signal to the control unit through the first signal line, and transmits the second off signal to the control unit through the second signal line,
The control unit is configured to switch the motor between the drive state and the stop state when both the first on signal and the second on signal are detected,
The control unit is configured to cause the switch to control when the first on signal and the second off signal are received for a first time, or when the first off signal and the second on signal are received for a first time. regulating starting of the motor;
Further, the control unit receives the first off signal and the second off signal, and then converts the first on signal and the second off signal or the first off signal and the second on signal into a second on signal. regulating the starting of the motor by the switch when the first off signal and the second off signal are received for a period of time or more;
The power tool, wherein the second time is set shorter than the first time. 2. The motor according to claim 1, wherein the motor is configured not to switch from the stopped state to the drive state even if an operator operates the switch when the motor is in the stopped state and the first signal line is disconnected. power tools. 3. The motor is configured to switch the motor from the driving state to the stopped state when a worker operates the switch when the motor is in the driving state and the first signal line is disconnected. Power tools. 4. The motor according to claim 1, wherein the motor is configured to automatically switch the motor from the drive state to the stop state when the second signal line is disconnected in the drive state, regardless of an operation on the switch. Power tools listed in section. The control unit is configured to restrict starting of the motor when the first signal line is disconnected, and also restrict starting of the motor when the second signal line is disconnected.
A power tool according to any one of claims 1 to 4 . an operation section for switching the switch between the on state and the off state by an operation of a worker;
The operating portion is in the on position while an operating force is applied to move it to the on position, and is in the off position when no operating force is applied,
The power tool according to any one of claims 1 to 5 , wherein the switch is in an on state when the operating portion is in the on position, and is in an off state when the operating portion is in the off position. An output shaft capable of holding a tip tool,
a power transmission unit that converts the rotation of the motor into reciprocating motion and transmits it to the output shaft;
a housing section that houses the power transmission section;
The power tool according to any one of claims 1 to 6 , wherein the switch is supported by the housing. The power tool according to claim 6 , having two sets of the operating portion and the switch, one set and the other set being provided on one side and the other side, respectively, with the rotation shaft of the motor interposed therebetween. The power tool according to claim 8 , wherein even if one set of switches is in an abnormal state, the control unit can control the motor based on a signal received from the other set of switches. 7. The switch has a plunger that is pressed and operated by the operating section, and switches the state of the signal transmitted by the first signal line and the second signal line depending on the position of the plunger. Power tools.

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