Work machine

Abstract

Provided is a work machine having improved convenience. A nailing machine 10 includes a motor 22, a control unit 30, a 5V generation circuit 74, and a switching unit 40. The control unit 30 controls driving of the motor 22. The 5V generation circuit 74 can switch between a power supply state and a stop state to the control unit 30. The switching unit 40 has a switch part 43, the switching unit 40 switching between a state of supplying electric power to the 5V generation circuit 74 and a state of stopping the supply of electric power. When the switch part 43 is switched to an ON state, the switching unit 40 switches the state of the 5V generation circuit 74 to the supply state. When the switch part 43 maintains the ON state and a first prescribed time elapses, the switching unit 40 switches the state of the 5V generation circuit 74 to the stopped state.

Description

Work equipment

[0001] The present invention relates to a work machine.

[0002] The work machine described in Patent Document 1 includes a drive source, a control circuit, and first and second operating units whose positions can be switched by an operator. The control circuit makes a first on-determination and a first off-determination to determine movement of the first operating unit, and a second on-determination and a second off-determination to determine movement of the second operating unit.

[0003] International Publication No. 2021 / 220703

[0004] In a work machine that determines whether an operating unit is on or off, such as the work machine described in Patent Document 1, if the operating unit fails or becomes unable to switch on or off, the on state continues to be output. As a result, even when the operation should be turned off, the on state of the operation continues, which may waste power. In other words, there is a risk that the convenience of the work machine may be reduced.

[0005] An object of the present invention is to provide a work machine with improved convenience.

[0006] In one embodiment, a work machine includes a motor, a control unit that controls driving of the motor, a power supply unit that is switchable between a supply state in which power is supplied to the control unit and a stop state in which power is not supplied to the control unit, and a switching unit that switches the operating state of the power supply unit between the supply state and the stop state. The switching unit has a switch that is switched between an on state and an off state by an operator. When the switch unit is switched from the off state to the on state while the power supply unit is in the stop state, the switching unit switches the state of the power supply unit from the stop state to the supply state, and even if the switch unit maintains the on state, the switching unit switches the state of the power supply unit from the supply state to the stop state after a first predetermined time has elapsed.

[0007] According to the present invention, the convenience of the work machine can be improved.

[0008] 2 is a right side view showing the internal structure of a work machine according to an embodiment of the present invention; FIG. 3 is a view showing the structure of a main part of the nail gun shown in FIG. 1 at a standby position; FIG. 4 is a view showing the main part of the nail gun shown in FIG. 1 at a standby position as viewed from the direction of arrow A in FIG. 2; FIG. 5 is a view showing the structure of a main part of the nail gun shown in FIG. 1 at top dead center; FIG. 6 is a view showing the structure of a main part of the nail gun shown in FIG. 1 at bottom dead center during normal operation; FIG. 7 is a circuit block diagram showing the configuration of a main part of the nail gun shown in FIG. 1; FIG. 8 is a timing chart showing changes in each item when a push switch is turned on after a battery is connected to the nail gun shown in FIG. 1; FIG. 9 is a timing chart showing changes in each item when a control unit determines that a battery is connected in the nail gun shown in FIG. 1;

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in all drawings referred to for describing the embodiments, the same reference numerals are used for identical or substantially identical configurations and elements. Furthermore, as a general rule, configurations and elements that have already been described will not be described repeatedly.

[0010] [Configuration of the Nailer] Figure 1 shows a nailer 10, which is an example of a work machine. In Figure 1, the direction indicated by arrow B1 is the downward direction, and the direction indicated by arrow B2 is the upward direction. Directions that are perpendicular to the up-down direction and perpendicular to each other are referred to as the front-rear direction and the left-right direction. The nailer 10 drives a nail N, which is an example of a fastener, into a mating material G by striking it. The nailer 10 has a housing 11, which is an example of a main body of the nailer 10.

[0011] The nail gun 10 (housing 11) includes a motor 22, a control unit 30, a 5V generating circuit 74 (FIG. 6), and a switching unit 40. The housing 11 also includes a cylindrical portion 12, a motor case 14, a handle 15, and an attachment portion 16.

[0012] The tubular portion 12 is formed in a cylindrical shape extending in the up-down direction. The motor case 14 is formed in a tubular shape extending rearward from the tubular portion 12. The handle 15 is formed in a tubular shape extending rearward from the tubular portion 12. The handle 15 is located above the motor case 14. The handle 15 is gripped by an operator.

[0013] The mounting portion 16 connects the rear end of the motor case 14 and the rear end of the handle 15 in the vertical direction. A battery 32 is electrically connected to the mounting portion 16. The battery 32 is provided so as to be connectable (attachable) to and detachable from the mounting portion 16.

[0014] The cylindrical portion 12 houses a winding gear 26, a plunger 34, a driver blade 36, a spring 37, a counterweight 38, etc. An ejection portion 13 that supports the nails N so that they can be ejected is provided below the cylindrical portion 12. A magazine 19 that can hold a plurality of nails N is attached below the motor case 14. The nails N held in the magazine 19 are sent out one by one to the ejection portion 13. A push lever 42 is provided below the cylindrical portion 12.

[0015] <Motor> The motor 22 is housed in the motor case 14 together with the gear box 24. The motor 22 has a rotor and a stator (not shown). When power is supplied from the battery 32, the rotor of the motor 22 rotates, and the motor shaft attached to the rotor also rotates. The motor 22 is, for example, a brushed motor.

[0016] The gearbox 24 has an input element, a planetary gear mechanism, and an output element. The input element is connected to the motor shaft of the motor 22 and rotates integrally with the motor shaft of the motor 22. The output element is connected to the rotation shaft of a first gear 27 (FIG. 2) and rotates integrally with the motor shaft. The first gear 27 forms a part of the winding gear 26.

[0017] When the driving force generated by the rotation of the motor shaft is transmitted to the input element, it is decelerated by the planetary gear mechanism and then transmitted to the output element. In other words, the driving force generated by the rotation of the motor 22 is transmitted to the first gear 27. The motor 22, the gearbox 24, and the first gear 27 are arranged coaxially along the front-rear direction.

[0018] <Control Unit> The control unit 30 is operable, for example, by a 5V power supply, and controls the driving and stopping of the motor 22. The 5V power supply that enables the control unit 30 to operate is supplied to the control unit 30 from a 5V generation circuit 74 (FIG. 6) described later.

[0019] The control unit 30 is provided inside the mounting unit 16, for example. Specifically, the control unit 30 includes a CPU (Central Processing Unit), a memory unit, storage, and a timer, and functions as a computer. The control unit 30 can control the operation of not only the motor 22 but also each part of the nail gun 10. The memory unit or storage stores various data including programs executed by the CPU. Programs can be loaded into a portion of the memory unit.

[0020] <Battery> The battery 32 is connected to the attachment portion 16. In other words, the battery 32 is an example of a connection power supply portion that can be connected to the housing 11. When connected to the housing 11, the battery 32 supplies power to a 5V generation circuit 74 ( FIG. 6 ) and the switching portion 40, which will be described later. The battery 32 is a DC power source and has multiple battery cells. The battery cells may be, for example, lithium-ion batteries, nickel-metal hydride batteries, lithium-ion polymer batteries, or nickel-cadmium batteries.

[0021] <Switching Unit> The switching unit 40 switches the operating state of the 5V generation circuit 74 (FIG. 6) described below between a supply state and a stopped state. The switching unit 40 includes at least a switch unit 43, a blocking circuit 72, a differentiating circuit 73, a branching circuit 75, and transistors T1 and T2.

[0022] <<Operation Unit and Switch Unit>> The switch unit 43 is switched between an on state and an off state when an operator operates the operation unit 41. The switch unit 43 includes, for example, a push switch PS (FIG. 6) and a trigger switch TS (FIG. 6).

[0023] The operation unit 41 includes, for example, a push lever 42 and a trigger 44. When the push lever 42 is pressed by contact with a mating object G, the push lever 42 is turned on. When the trigger 44 is pressed by an operator's finger, the trigger 44 is turned on. When the pressure acting on the push lever 42 is released, the push lever 42 is turned off. When the pressure acting on the trigger 44 is released, the trigger 44 is turned off. Note that the operation unit 41 may include only the push lever 42. When the push lever 42 is in the on state, the push switch PS ( FIG. 6 ) is turned on (conductive state). When the push lever 42 is in the off state, the push switch PS is turned off (interrupted state). When the trigger 44 is in the on state, the trigger switch TS ( FIG. 6 ) is turned on. When the trigger 44 is in the off state, the trigger switch TS is turned off.

[0024] <<<<Push Lever and Push Switch>>> The push lever 42 is provided spaced apart from the handle 15 in the up-down direction. The lower end of the push lever 42 is located below the injection section 13. The push lever 42 becomes movable by abutting against the target material G. The push lever 42 abuts against or disengages from the target material G when the entire nailer 10 (housing 11) is moved up or down by the operator. This switches the push lever 42 between an on state and an off state. "The push lever 42 abuts against the target material G" means that the lower end of the push lever 42 abuts against the target material G.

[0025] Specifically, when the lower end of the push lever 42 abuts against the mating material G, the push lever 42 moves upward and turns into the ON state due to the reaction force from the mating material G. When the lower end of the push lever 42 separates from the mating material G, the push lever 42 moves downward due to the biasing force of a spring (not shown) and turns into the OFF state.

[0026] The push switch PS shown in FIG. 6 is an example of the switch unit 43. When the push switch PS is in the on state, it allows current to flow through a path K3 (described later), and when it is in the off state, it prevents current from flowing through the path K3. The push switch PS also functions as a switch to start the control unit 30 and a switch to operate the motor 22, but basically operates the motor 22. A SW state detection circuit 76 (described later) sends a signal indicating the on or off state of the push switch PS to the control unit 30. A SW state detection circuit 88 sends a signal indicating the on or off state of the trigger switch TS to the control unit 30.

[0027] <<<Trigger and Trigger Switch>>> As shown in FIG. 1 , the trigger 44 is provided on the handle 15. The trigger 44 is actuated by being operated by the operator. Specifically, the trigger 44 moves upward when pulled by the finger of the operator holding the handle 15. At this time, the trigger switch TS ( FIG. 6 ) is turned on. The trigger 44 is also provided with a spring (not shown). The biasing force of this spring causes the trigger 44 to move downward. At this time, the trigger switch TS is turned off. In this way, the push lever 42, the push switch PS ( FIG. 6 ), the trigger 44, and the trigger switch TS are operated indirectly or directly by the operator.

[0028] <<Settings of Switching Unit>> An example of the settings of the switching unit 40 will be described. When the push lever 42 switches from the OFF state to the ON state while the 5V generation circuit 74 (FIG. 6) is in the stopped state, the switching unit 40 switches the state of the 5V generation circuit 74 (FIG. 6) from the stopped state to the supply state. In other words, when the push lever 42 switches from the OFF state to the ON state, the state of the 5V generation circuit 74 switches from the stopped state to the supply state. Even if the push lever 42 remains in the ON state, when the first predetermined time TA (FIG. 7) has elapsed, the switching unit 40 switches the state of the 5V generation circuit 74 from the supply state to the stopped state.

[0029] The "first predetermined time TA" is a time that serves as a boundary value for determining whether or not power is being supplied appropriately from the battery 32 when the push lever 42 is in the ON state, and is a time that is set in advance in the control unit 30. The first predetermined time TA is the elapsed time after the push lever 42 (push switch PS (FIG. 6)) is switched to the ON state, and is set to, for example, a time between 5 minutes and 10 minutes.

[0030] <Other Configurations of the Nailer> Figure 2 shows the internal configuration of the nailer 10. The nailer 10 has a winding gear 26, a plunger 34, a driver blade 36, a spring 37, a counterweight 38, and the like, all housed in the cylindrical portion 12 (Figure 1).

[0031] As shown in Figure 3, when the motor 22 (Figure 1) is driven, the winding gear 26 rotates in a third direction indicated by an arrow B3. When the motor 22 is stopped, the winding gear 26 can rotate in a fourth direction opposite to the third direction. The fourth direction is indicated by an arrow B4.

[0032] The winding gear 26 includes three gears: a first gear 27 located in the lower stage, a second gear 28 located in the middle stage, and a third gear 29 located in the upper stage. The first gear 27, the second gear 28, and the third gear 29 are rotatably mounted on the holding plate 21 (see FIG. 1). The first gear 27 meshes with the second gear 28, and the second gear 28 meshes with the third gear 29.

[0033] A first cam roller 45 is provided on the front surface of the first gear 27, and is positioned eccentrically with respect to the rotation axis of the first gear 27. A second cam roller 46 and a third cam roller 47 are provided on the front surface of the second gear 28, and are positioned eccentrically with respect to the rotation axis of the second gear 28. A fourth cam roller 48 and a fifth cam roller 49 are provided on the front surface of the third gear 29, and are positioned eccentrically with respect to the rotation axis of the third gear 29. Each cam roller is capable of rotating on its own axis while revolving around its respective rotation axis.

[0034] As shown in Fig. 1, a top holder 52 is fixed to the upper part of the cylindrical portion 12. A bottom holder 54 is fixed to the lower part of the cylindrical portion 12. A guide bar 56 is provided between the top holder 52 and the bottom holder 54. The upper end of the guide bar 56 is fixed to the top holder 52. The lower end of the guide bar 56 is fixed to the bottom holder 54.

[0035] As shown in Figure 3, two guide bars 56 are provided spaced apart in the left-right direction. A guide shaft 58 is provided between the two guide bars 56. The upper end of the guide shaft 58 is fixed to the top holder 52. The lower end of the guide shaft 58 is fixed to the bottom holder 54. The plunger 34 and the counterweight 38 are disposed between the two guide bars 56.

[0036] The plunger 34 is movable up and down along the guide shaft 58 and the guide bar 56. A driver blade 36 is fixed to the plunger 34. The driver blade 36 is movable up and down together with the plunger 34. The lower end of the driver blade 36 protrudes downward from the cylindrical portion 12 (FIG. 1), and can strike the nail N in the ejection portion 13 (FIG. 1) by moving downward. The plunger 34 and the driver blade 36 constitute the striking portion 33. The counterweight 38 reduces the recoil when the striking portion 33 strikes the nail N.

[0037] The spring 37 is provided between the plunger 34 and the counterweight 38. The upper end of the spring 37 is fixed to the counterweight 38. The lower end of the spring 37 is fixed to the plunger 34. The spring 37 is, for example, a compression coil spring. The spring 37 urges the plunger 34 downward and urges the counterweight 38 upward.

[0038] A lower bumper 55 is provided between the bottom holder 54 and the plunger 34. An upper bumper 59 is provided between the top holder 52 and the counterweight 38.

[0039] The guide shaft 58 is inserted through the lower bumper 55, the plunger 34, the spring 37, the counterweight 38, and the upper bumper 59. A first rack 62 and a second rack 63 are fixed to the plunger 34.

[0040] The first cam roller 45 is engageable with the first rack 62. The second cam roller 46 and the third cam roller 47 are engageable with the second rack 63. The first cam roller 45, the second cam roller 46, and the third cam roller 47 are engageable with the plunger 34 via the first rack 62 or the second rack 63.

[0041] A third rack 64 is fixed to the counterweight 38. The fourth cam roller 48 and the fifth cam roller 49 are engageable with the third rack 64. The fourth cam roller 48 and the fifth cam roller 49 rotate while engaged with the counterweight 38 via the third rack 64, thereby moving the counterweight 38 downward.

[0042] As shown in Figure 4, a latch 66 is attached to the left guide bar 56. The latch 66 is rotatable about a support shaft 68 relative to the guide bar 56. The support shaft 68 is located within the range of the third gear 29 in the vertical direction. The latch 66 is biased clockwise by a torsion coil spring.

[0043] The latch 66 has a hook 66A and an arm 66B. The hook 66A and the arm 66B are arranged in the longitudinal direction of the latch 66, separated by a support shaft 68. The hook 66A can engage with and disengage from an engagement pin 69 provided on the counterweight 38. The arm 66B can contact and separate from the plunger 34. The counterweight 38 and the striking portion 33 are both wound up by the winding gear 26, and their operations are linked.

[0044] Fig. 2 shows the plunger 34 in a standby position (first position), Fig. 4 shows the plunger 34 in a top dead center position (second position), and Fig. 5 shows the plunger 34 in a bottom dead center position (third position).

[0045] 2, 4, and 5, when the striking portion 33 is engaged with the winding gear 26, the striking portion 33 moves from the standby position to the top dead center against the biasing force of the spring 37 as the winding gear 26 rotates. Furthermore, when the striking portion 33 is disengaged from the winding gear 26 at the top dead center, the striking portion 33 is able to move from the top dead center to the bottom dead center by the biasing force of the spring 37 and strike the nail N.

[0046] <Circuit Block Diagram> Figure 6 shows a circuit block diagram of the nail gun 10. Components already described are given the same reference numerals and will not be described again. The nail gun 10 has a main circuit unit 70. The battery 32 supplies power to the main circuit unit 70 via a connector 18 provided in the mounting portion 16.

[0047] <<Main Circuit Unit>> The main circuit unit 70 includes a control unit 30, a shutoff circuit 72, a differentiating circuit 73, a 5V generating circuit 74, a branching circuit 75, SW state detection circuits 76 and 88, a delay circuit 78, a battery state detection circuit 82, a control signal output circuit 84, and an inverter circuit 86. The main circuit unit 70 also includes a push switch PS, a trigger switch TS, resistors R1, R2, and R3, capacitors C1 and C2, diodes D1, D2, D3, D4, and ZD, and transistors T1, T2, T3, T4, T5, and T6.

[0048] Furthermore, the current path extending from the connector 18 to the inverter circuit 86 is referred to as path K1. The current path extending from the connector 18 to the 5V generation circuit 74 is referred to as path K2. The current path provided with the push switch PS is referred to as path K3. Path K3 is an example of a first path. Current flows through path K3, enabling power to be supplied to the 5V generation circuit 74. The current path extending from the control unit 30 to transistor T3 is referred to as path K4. The current path connected from path K2 to path K3 via transistor T4 and diode D1 is referred to as path K5. Path K5 is an example of a second path. The current path extending from the SW state detection circuit 76 to the control unit 30 is referred to as path K6.

[0049] The current path branching from path K2 and extending to transistor T5 is path K7. The current path extending from battery state detection circuit 82 to control unit 30 is path K8. The current path extending from control unit 30 to transistor T6 is path K9. The current path extending from SW state detection circuit 88 to control unit 30 is path K10. The current path extending from trigger switch TS to SW state detection circuit 88 is path K11. Note that current paths not included in paths K1 to K11 are simply referred to as "current paths."

[0050] The emitter E of transistor T1 is grounded. The base B of transistor T1 is connected (electrically connected) to push switch PS via path K3. The collector C of transistor T1 is connected to the base B of transistor T2 and the SW state detection circuit 76. Transistor T2 is located between the shutoff circuit 72 and the 5V generation circuit 74 via path K2. The collector C of transistor T2 is connected to the 5V generation circuit 74. The emitter E of transistor T2 is connected to path K2.

[0051] The base B of the transistor T3 is connected to the control unit 30. The emitter E of the transistor T3 is grounded. The collector C of the transistor T3 is connected to the base B of the transistor T4. The emitter E of the transistor T4 is connected to the path K2. The collector C of the transistor T4 is connected to the path K3.

[0052] The base B of the transistor T5 is connected to the path K7. The collector C of the transistor T5 is connected to the battery state detection circuit 82. The emitter E of the transistor T5 is grounded. The base B of the transistor T6 is connected to the control unit 30. The emitter E of the transistor T6 is grounded.

[0053] Diode D1 is located between transistor T4 and path K3 (push switch PS). Diode D2 is located between transistors T1 and T2. Diode D3 is located between the SW state detection circuit 76 and the collector C of transistor T1. Diode D4 is connected between transistor T2 and diode D2 and between transistors T3 and T4. Diode ZD is provided on path K7.

[0054] <<<Shutoff Circuit>>> The switching unit 40 (FIG. 1) includes a shutoff circuit 72. The shutoff circuit 72 is connected in series to the upstream side of the push switch PS on path K3 and is configured to be able to shut off the current on path K3. When a second predetermined time TB (FIG. 7) has elapsed since the push lever 42 (push switch PS) was switched from the OFF state to the ON state, the shutoff circuit 72 shuts off the current on path K3. The shutoff circuit 72 includes a differentiating circuit 73.

[0055] The "second predetermined time TB" is a time shorter than the above-mentioned first predetermined time TA, and is a time that is set in advance in the control unit 30. The second predetermined time TB is set to, for example, "several seconds."

[0056] <<<<<Differential Circuit>>>> The differential circuit 73 is a circuit provided in series with paths K2 and K3. As an example, the differential circuit 73 is made up of a resistor R1 and a capacitor C1 connected in parallel. The differential circuit 73 can make the second predetermined time TB that passes in the interrupter circuit 72 a momentary time with a pulse waveform. This is because even if charge accumulates in capacitor C1, the charge in capacitor C1 flows out through resistor R1.

[0057] <5V Generation Circuit> The 5V generation circuit 74 is an example of a power supply unit. The 5V generation circuit 74 generates a 5V DC voltage from the output voltage of the battery 32 and supplies power (power supply voltage) equivalent to 5V to the control unit 30, the SW state detection circuits 76 and 88, and the battery state detection circuit 82. The 5V generation circuit 74 can switch between a supply state in which power is supplied to the control unit 30 and a stop state in which power is not supplied to the control unit 30. When the transistor T2 is turned on, the 5V generation circuit 74 is in a supply state by supplying power from the battery 32 through the path K2. When the transistor T2 is turned off, the 5V generation circuit 74 is in a stop state by not supplying power from the battery 32 through the path K2. The "5V" symbol in FIG. 6 indicates a voltage generated by the 5V generation circuit 74.

[0058] <<<Branch Circuit>>> The switching unit 40 includes a branch circuit 75. The branch circuit 75 is capable of switching between blocking and not blocking the current in path K5, which is electrically connected in parallel with the blocking circuit 72. The branch circuit 75 includes, as an example, transistors T3 and T4 and a diode D1. The branch circuit 75 does not block the current in path K5 when a POWERKEEP signal is sent from the control unit 30, and blocks the current in path K5 when a POWERKEEP signal is not sent from the control unit 30.

[0059] The "POWERKEEP signal" is a signal that instructs the control unit 30 whether or not to maintain the supply of 5V power supply voltage by the 5V generation circuit 74. When the POWERKEEP signal is on, it means that the control unit 30 has issued an instruction to supply power supply voltage. When the POWERKEEP signal is off, it means that the control unit 30 has issued an instruction to stop the supply of power supply voltage.

[0060] <<<<SW State Detection Circuit>>> When the push switch PS is in the on (connected) state, the SW state detection circuit 76 detects the on state of the push switch PS by utilizing the fact that when a current flows from the collector C to the emitter E of the transistor T1, the voltage in the SW state detection circuit 76 changes.

[0061] Furthermore, when the push switch PS is in the off (disconnected) state, no current flows from the collector C to the emitter E of the transistor T1, and no change occurs in the voltage at the SW state detection circuit 76, thereby detecting the off state of the push switch PS. Information on the on / off state of the push switch PS detected by the SW state detection circuit 76 is sent to the control unit 30.

[0062] The SW state detection circuit 88 detects the on (connected) state or off (disconnected) state of a trigger switch TS, which will be described later, based on the presence or absence of electricity in the SW state detection circuit 88. Information on the on or off state of the trigger switch TS detected by the SW state detection circuit 88 is sent to the control unit 30.

[0063] <<<Delay Circuit>>> The delay circuit 78 includes, for example, resistors R2 and R3 and a capacitor C2. In this embodiment, the delay circuit 78 also includes a transistor T5. When the battery 32 is connected to the housing 11, power is supplied to path K7 through diode ZD. The delay circuit 78 delays the time it takes for the power supplied to path K7 to reach the base B (gate) of transistor T5. In other words, when the battery 32 is connected to the attachment portion 16, the delay circuit 78 delays the timing at which transistor T5 turns on. The delay circuit 78 is used to distinguish between a case in which the battery 32 is connected to the housing 11 after the push switch PS has turned on and a case in which the push switch PS is turned on after the battery 32 has been connected to the housing 11.

[0064] <<<Battery Status Detection Circuit>>> The battery status detection circuit 82 is an example of a detection circuit for detecting the presence or absence of a battery 32. The battery status detection circuit 82 detects whether the battery 32 is connected to the housing 11 (mounting portion 16). Specifically, the battery status detection circuit 82 sends a battery detection signal to the control unit 30 when a third predetermined time TC ( FIG. 8 ), which is shorter than the first predetermined time TA ( FIG. 7 ), has elapsed since detecting that the battery 32 is connected to the housing 11. Note that when transistor T5 is on and the voltage obtained by the battery status detection circuit 82 is 0 V, the battery status detection circuit 82 determines that the battery 32 is connected to the housing 11 and sends a battery detection signal (battery present) to the control unit 30.

[0065] <<<<Control Signal Output Circuit>>>> The control signal output circuit 84 operates the inverter circuit 86 based on a command from the control unit 30 .

[0066] <<<<Inverter Circuit>>> The inverter circuit 86 converts the direct current supplied from the battery 32 into alternating current and supplies it to the motor 22. The inverter circuit 86 includes, for example, switching elements S1, S2, and S3.

[0067] <<<<Trigger Switch>>> The trigger switch TS is turned on when the trigger 44 is grasped (depressed) by the operator. In addition, when the pressing force acting on the trigger 44 is released while the trigger switch TS is in the on state, the trigger switch TS is turned off.

[0068] 6 sends an ON signal to switching unit 40 so that switching unit 40 sets the state of 5V generation circuit 74 to the supply state until the second predetermined time TB (FIG. 7) has elapsed since power supply from 5V generation circuit 74 started. Specifically, control unit 30 sends a POWERKEEP signal to branch circuit 75 via path K4 until the second predetermined time TB has elapsed since power supply from 5V generation circuit 74 started.

[0069] If the switch unit 43 does not switch between the on state and the off state until a first predetermined time TA has elapsed after sending an on signal to the switching unit 40, the control unit 30 stops sending the on signal to the switching unit 40. Furthermore, when the initial setting is completed, the control unit 30 energizes the base B of the transistor T6 via path K9.

[0070] When the push lever 42 is turned on first and the trigger 44 is turned on, the control unit 30 drives the motor 22. Also, the control unit 30 is set so as not to drive the motor 22 even if the push lever 42 is turned on first and the trigger 44 is turned on first.

[0071] [Explanation of Comparative Example] As a comparative example to the nail driver 10 of the present embodiment, a configuration without the differential circuit 73 (in other words, a configuration in which the push switch PS is directly connected to the connector 18) will be described. Note that illustration of the configuration of the comparative example will be omitted.

[0072] If the push switch PS is kept on in a configuration without the differential circuit 73, the power (current) supplied from the battery 32 will continue to flow to the ground via the push switch PS, resulting in unnecessary current consumption.

[0073] Furthermore, while the push switch PS is maintained in the ON state, the control unit 30 remains activated. In the comparative example, let's assume that the control unit 30 is left unused for, say, 15 minutes after activation, and the control unit 30 performs a shutdown process to turn transistor T3 OFF. In this case, if the push switch PS is maintained in the ON state, even if the control unit 30 turns transistor T3 OFF, the current flowing from the push switch PS will turn transistor T2 ON. This makes it impossible to shut down the control unit 30. Thus, the configuration of the comparative example wastes power (current).

[0074] [Operation of Nail Driver] The operation of the nail driver 10 of this embodiment will be described with reference to Fig. 6. For components of the nail driver 10 that are not shown in Fig. 6, reference will be made to Figs. 1 to 5, and individual figure numbers will be omitted. Each process performed by the nail driver 10 is performed in the control unit 30 by the CPU reading a processing program from the memory unit, expanding the program into a part of the memory, and executing the program.

[0075] <Functions of Differentiating Circuit and Branching Circuit> Here, the following description will be made mainly focusing on the differentiating circuit 73 and the branching circuit 75.

[0076] <<Starting of Control Unit>> When the push switch PS is turned on (connected), the transistor T1 is momentarily turned on (for the second predetermined time TB) by power being supplied from the battery 32 via the differentiation circuit 73. In other words, the differentiation circuit 73 instantaneously passes a pulse waveform current to the transistor T1.

[0077] When transistor T1 momentarily turns on, transistor T2 momentarily turns on, and power from battery 32 is supplied to 5V generation circuit 74 via path K2. Then, 5V power (power supply voltage) is supplied from 5V generation circuit 74 to control unit 30. This causes control unit 30 to momentarily turn on (start-up state).

[0078] The control unit 30 sends a POWERKEEP signal to the branch circuit 75 (transistor T3) via path K4 during the second predetermined time TB (FIG. 7) (instant) after the start of power supply from the 5V generation circuit 74. Therefore, even if the transistor T1, which momentarily turns on, immediately turns off, the transistor T3 remains on, allowing the transistor T2 to maintain its on state. In other words, the control unit 30 can continue to operate.

[0079] Here, as a comparative example, in a configuration that does not have the branch circuit 75 and has only the differentiation circuit 73, even if the push switch PS is turned on, the transistor T1 can only be turned on for the second predetermined time TB.

[0080] On the other hand, in the nail gun 10 of this embodiment, since it has not only the differential circuit 73 but also the branch circuit 75, the control unit 30 can continue to be activated even when the transistor T1 is turned off. As a result, the 5V generation circuit 74 continues to supply power equivalent to 5V to each part.

[0081] <<Detection of Long-Pressed Push Switch>> The control unit 30 can detect a long-pressed state of the push switch PS (a state in which the ON operation is continued). Specifically, when the transistor T3 is in the ON state (operating state), a current flows from the collector C to the emitter E of the transistor T3, turning the transistor T4 on (operating state), and power is supplied to the push switch PS.

[0082] In other words, even if the differential circuit 73 can only supply power momentarily, when the control unit 30 is in the on state, power from the battery 32 is supplied to the push switch PS via the branch circuit 75. In this way, since the nail gun 10 is provided with the branch circuit 75, the SW state detection circuit 76 can detect that the push switch PS is being pressed and held.

[0083] <<Nail Driving Operation>> When the push switch PS is in the ON state and the trigger switch TS is in the ON state, the control unit 30 drives the motor 22 to drive the nail N. However, the nail gun 10 allows the motor 22 to be driven if the trigger 44 is turned on after the push lever 42 is turned on, but does not allow the motor 22 to be driven if the push lever 42 is turned on after the trigger 44 is turned on.

[0084] On the other hand, when at least one of the push switch PS and the trigger switch TS is in the OFF state, the control unit 30 does not permit the motor 22 to be driven.

[0085] In the nail gun 10, the differential circuit 73 is provided immediately before the push switch PS, so even if the push switch PS is pressed for a long time, the power supply through the path K3 can be cut off at the moment when the push switch PS is pressed (the second predetermined time TB). Therefore, the power consumption of the nail gun 10 can be reduced compared to the configuration of the comparative example described above.

[0086] <<Shutdown of the Control Unit>> In the nail gun 10, if the time during which the push switch PS remains in either the on or off state exceeds a first predetermined time TA, the control unit 30 stops sending the POWERKEEP signal. As a result, even if the push switch PS is in the on state, transistor T3 is turned off, and transistor T4 is turned off, which turns transistor T1 off, and transistor T2 is turned off. Even if the push switch PS is in the off state, transistor T3 is turned off, which turns transistor T2 off. In other words, when the branch circuit 75 is turned off, transistor T2 is turned off, and the 5V generation circuit 74 is stopped. As described above, the control unit 30 can switch the 5V generation circuit 74 from a supply state to a stopped state even when the push switch PS remains in the on state. This allows the control unit 30 to be shut down, further reducing power consumption compared to the comparative example described above, in which the control unit continues to operate.

[0087] <Function of Delay Circuit> When the battery 32 is connected to the housing 11, power is supplied from the battery 32 to the path K7 via the diode ZD. The delay circuit 78 delays the time it takes for the power supplied to the path K7 to reach the base B of the transistor T5.

[0088] <<When the Battery is Connected Before the Push Switch is Turned On>> When the push switch PS is in the OFF state and the battery 32 is connected to the housing 11, power from the battery 32 reaches the transistor T5 via the delay circuit 78, causing the transistor T5 to slowly turn on. At this point, the battery state detection circuit 82 has not yet detected the battery 32.

[0089] When the push switch PS is turned on, the transistors T1 and T2 are momentarily turned on by the action of the differentiation circuit 73. This activates the control unit 30. When the control unit 30 is activated, the transistor T5 is on and the battery state detection circuit 82 detects the battery 32, so the control unit 30 determines that the battery 32 is connected to the housing 11. This causes the control unit 30 to permit the motor 22 to be driven. In other words, the motor 22 can begin to be driven.

[0090] <<When the Push Switch is Turned On Before the Battery is Connected>> Let's assume that the push switch PS is pressed by an operator and is in the on state. If the battery 32 is connected to the housing 11 in this state, power from the battery 32 is supplied to the push switch PS and the delay circuit 78 almost simultaneously. Here, on the delay circuit 78 side, the delay circuit 78 slowly turns on, so the transistor T5 does not immediately turn on.

[0091] On the other hand, on the side of the cutoff circuit 72, the push switch PS is momentarily turned on via the differential circuit 73, and the transistors T1 and T2 are turned on, thereby starting up the control unit 30. In this way, the control unit 30 starts up before the transistor T5 is turned on.

[0092] When the control unit 30 is started, the transistor T5 is not in the ON state, so the battery state detection circuit 82 sends a "no battery" signal to the control unit 30. In other words, when the control unit 30 is started, it determines that the battery 32 is not connected to the housing 11 and does not allow the motor 22 to operate. Therefore, even if the push switch PS and the trigger switch TS are both in the ON state at this point, the motor 22 remains stopped.

[0093] <Operation when initial settings are completed> After the control unit 30 is started, it sends an "initial settings completed" signal to the base B of the transistor T6 when it has completed determining whether or not the battery 32 is present. This activates the transistor T6, and the charge stored in the capacitor C2 is discharged.

[0094] As a comparative example, in a configuration in which charge accumulates in capacitor C2 each time the battery 32 is inserted or removed (disconnected or connected), the delay circuit 78 may not operate, and the battery state detection circuit 82 may not function correctly. In other words, there is a possibility that the presence or absence of the battery 32 may not be detected correctly.

[0095] On the other hand, in the nail gun 10 of this embodiment, when the initial setting is completed, the control unit 30 operates the transistor T6, which drains the charge from the capacitor C2. This allows the transistor T5 to operate normally, and the battery state detection circuit 82 to operate correctly, so the control unit 30 can correctly detect whether the battery 32 is present.

[0096] <Charts when the push switch is pressed after the battery is connected> Figure 7 shows a timing chart showing the time changes of each item from time t1 to time t6 when the push switch PS is pressed and held after the battery 32 is connected to the nail gun 10 (Figure 1) of this embodiment. Although times t1 to t6 are arranged in numerical order, the intervals between each time are not constant. Note that times t2 to t6 correspond to a first predetermined time TA. Note that times t2 to t3 correspond to a second predetermined time TB. Note that for each component of the nail gun 10, reference should be made to Figures 1 to 6, and individual figure numbers will be omitted.

[0097] FIG. 7 shows battery voltage, PS voltage, 5V voltage, POWERKEEP, branch voltage, and PS switching as example items.

[0098] "Battery voltage" refers to the voltage at the connector 18. "PS voltage" refers to the voltage at a position on the path K3 between the push switch PS and the transistor T1. "5V voltage" refers to the voltage generated by the 5V generation circuit 74. "POWERKEEP" refers to the on / off state of the POWERKEEP signal sent from the control unit 30.

[0099] "Branch voltage" refers to the voltage at the base B of transistor T4. "PS switching" refers to the switching of the voltage input to the base B of transistor T1. In other words, "PS switching" refers to the on / off state of the push switch PS. Note that the voltages VA, VB, VC, VD, VE, VF, and VG shown in FIG. 7 are used only to distinguish between the voltages, and the order of the voltages and the magnitudes of the voltages are basically unrelated.

[0100] The battery voltage is VA until time t1, and after time t1 when the battery 32 is connected, it rises from VA to VB.

[0101] The PS voltage is VC until time t2, and when the push switch PS is turned on, it rises from VC to VE. From time t2 to time t3, the PS voltage drops from VE to VD (>VC), but after time t3 it rises again to VE. The PS voltage begins to drop from VE at time t5 when the POWERKEEP signal is turned off, and reaches VC at time t6.

[0102] The 5 V voltage is 0 V until time t2, and when the push switch PS is turned on, it rises from 0 V to 5 V. Then, when the POWERKEEP signal is turned off at time t5, it starts to drop from 5 V and reaches 0 V at time t6.

[0103] POWERKEEP is off until time t3, and on from time t3 to time t5, at which point POWERKEEP is turned off.

[0104] The branch voltage remains at voltage VF until time t3, at which point it rises to voltage VG. The branch voltage is maintained at voltage VG from time t3 to time t5, but drops to voltage VF after time t5.

[0105] In PS switching, the power supply switches from the OFF state to the ON state at time t2, and then switches back to the OFF state at time t6, a time when a first predetermined time TA has elapsed since time t2. Thereafter, the power supply remains in the OFF state. It can be said that PS switching occurs when the control unit 30 turns off the POWERKEEP signal at time t5, resulting in the OFF state at time t6. Therefore, time t6 can also be said to be the time of forced termination by the control unit 30.

[0106] Figure 8 shows a timing chart illustrating the time changes of each item from time t1 to time t6 when the push switch PS is continuously pressed after the battery 32 is connected. The chart shows the battery voltage, PS voltage, and 5V voltage, as well as the battery detection voltage, battery presence / absence, and initial setting completion. Time tA is a time after time t1 and before time t2. The period from time t1 to time tA corresponds to the third predetermined time TC. The battery voltage, PS voltage, and 5V voltage are the same as those in Figure 7, so their explanation will be omitted.

[0107] "Battery detection voltage" refers to the voltage input to base B of transistor T5. "Battery presence / absence" refers to the presence or absence of a battery 32, with information sent from the battery state detection circuit 82 to the control unit 30 indicating "present" if the battery 32 is connected to the housing 11 and "absent" if the battery 32 is not connected to the housing 11. "Initial settings completed" refers to the state in which the motor 22 is ready to be driven, with "completed" if the control unit 30 determines that the motor 22 can be driven and "not yet" if it determines that the motor 22 cannot be driven.

[0108] The battery detection voltage is voltage VH until time t1, and after time t1 when the battery 32 is connected, it increases from voltage VH to voltage VI and then voltage VJ until time tA. As long as the battery 32 is connected, voltage VJ is maintained even after time t6.

[0109] Regarding the presence or absence of a battery, there is no battery until time t2, there is a battery from time t2 to time t4, and there is no battery from time t4 onwards.

[0110] In the initial setting completion state, the initial setting is not completed until time t4, and the initial setting is completed and the state is "completed" from time t4 onwards.

[0111] <Charts for when a battery is connected after the push switch is pressed> Figure 9 shows a timing chart illustrating the change over time in each item from time t1 to time t6 when a battery 32 is connected to the housing 11 after the push switch PS is pressed. The chart shows the battery voltage, PS voltage, and 5V voltage, as well as the battery detection voltage, battery presence / absence, and initial setting completion. Time tB is a time after time t4 and before time t5. Note that the PS voltage and 5V voltage are the same as those in Figure 7, so their explanation will be omitted.

[0112] The battery voltage remains at voltage VA until time t2, and after time t2 when the battery 32 is connected, it rises from voltage VA to voltage VB.

[0113] The battery detection voltage remains at voltage VH until time t2, and after time t2 when the battery 32 is connected, it rises from voltage VH to voltage VI and then voltage VJ until time tB. While the battery 32 is connected, voltage VJ is maintained even after time t6. Because time tB is after time t4, the initial setting in the control unit 30 is completed before the battery detection voltage reaches voltage VJ.

[0114] In terms of the presence or absence of a battery, since it has been determined that the battery 32 is already absent by time t2, the battery is absent throughout the entire period from time t1 to time t6.

[0115] In the initial setting completion state, the initial setting is in an "incomplete" state until time t4, and is in a "completed" state from time t4 onwards. In this way, the initial setting is completed in a state where it is determined that there is no battery 32 up to time t2. Therefore, even if the operator subsequently turns on the trigger switch TS, the control unit 30 will not allow the motor 22 to be driven.

[0116] 7, 8, and 9 show examples of changes over time for each item. In other words, the changes over time for each item are not limited to the trends shown in FIGS. 7, 8, and 9.

[0117] <Summary of Operation of the Present Embodiment> The operation of the nail driver 10 will be summarized below with reference to Fig. 1 to Fig. 9. Note that individual drawing numbers for the components of the nail driver 10 will be omitted.

[0118] The control unit 30 of the nail gun 10 controls the driving of the motor 22 in a supply state in which power is supplied from the 5V generation circuit 74. When the switch unit 43 switches from an off state to an on state in a stopped state in which power is not supplied from the 5V generation circuit 74, the switching unit 40 switches the state of the 5V generation circuit 74 from a stopped state to a supply state. In other words, when the push lever 42 switches from an off state to an on state, the push lever 42 switches the state of the 5V generation circuit 74 from a stopped state to a supply state.

[0119] Even if the switch unit 43 remains on, when the first predetermined time TA has elapsed, the switching unit 40 switches the state of the 5V generation circuit 74 from a supply state to a stopped state. This reduces the power consumption of the 5V generation circuit 74. In other words, the convenience of the nail driver 10 can be improved.

[0120] In the nail gun 10, the interrupting circuit 72 included in the switching unit 40 interrupts the current on the path K3 when a second predetermined time TB has elapsed since the switch unit 43 was switched from the off state to the on state. This allows the state of the 5V generation circuit 74 to be switched to the stopped state by interrupting the path K3 even if the switch unit 43 remains on. This further reduces the power consumption of the 5V generation circuit 74.

[0121] In the nail gun 10, the second predetermined time TB that passes in the cutoff circuit 72 can be set to a more instantaneous time with a pulse waveform, so the second predetermined time TB can be set to a shorter time. Furthermore, compared to a configuration in which the processing performed in the cutoff circuit 72 is realized by control by the control unit 30, the possibility that normal control will not be possible due to a malfunction of the control unit 30 can be reduced.

[0122] In the nail gun 10, the control unit 30 sends an ON signal to the switching unit 40 during the second predetermined time TB from the start of power supply. As a result, even if the current is cut off by the cutoff circuit 72, the switching unit 40 sets the 5V generation circuit 74 to the supply state, so that the power supply to the control unit 30 can be maintained.

[0123] In the nail gun 10, when the control unit 30 does not send a POWERKEEP signal (ON signal), the branch circuit 75 cuts off the current on path K5. At this time, the differentiation circuit 73 also does not allow current to flow. As a result, no current flows on path K3 even if the push switch PS (switch unit 43) is in the ON state.

[0124] On the other hand, when the control unit 30 sends a POWERKEEP signal, the branch circuit 75 does not cut off the current on path K5. In other words, if the switch unit 43 is in the ON state, the current flows through path K3 even if the current is cut off by the cutoff circuit 72. This prevents the control unit 30 from erroneously determining that the switch unit 43 has been turned off midway through the process, even if the switch unit 43 remains in the ON state for a long period of time and the current is cut off by the cutoff circuit 72.

[0125] In the nail gun 10, if an abnormal state occurs in which the switch unit 43 does not switch between the on and off states, the control unit 30 stops sending an on signal to the switching unit 40, thereby preventing the control unit 30 from continuing to send an on signal to the switching unit 40 unnecessarily.

[0126] The nail gun 10 may have both a push lever 42 and a trigger 44, and the motor 22 is driven when the push lever 42 is turned on first and then the trigger 44 is turned on, but the motor 22 is not driven if the order is reversed. In this configuration, the 5V generation circuit 74 is in a supply state when the push lever 42 is turned on, so the control unit 30 can be quickly started to drive the motor 22, resulting in smooth operation. Conversely, if the trigger 44 is turned on first, the motor 22 is not driven in the first place, and there is no need to start the control unit 30 when the trigger 44 is turned on. Therefore, by removing the function required as part of the switching unit 40 from the trigger 44, the circuitry of the nail gun 10 can be simplified.

[0127] In the nail gun 10, the battery state detection circuit 82 sends a detection signal to the control unit 30 when a third predetermined time TC has elapsed since it detected that the battery 32 was connected to the housing 11. Here, let us assume that the battery 32 is connected to the housing 11, and immediately after the battery state detection circuit 82 detects the connection of the battery 32 (before the third predetermined time TC has elapsed), the battery 32 is removed from the housing 11. In this case, the battery state detection circuit 82 can detect that the battery 32 is not connected to the housing 11, thereby preventing erroneous detection by the battery state detection circuit 82.

[0128] [Modifications] The present embodiment is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. Modifications of the present embodiment will be described below.

[0129] The nail gun 10 does not necessarily have to be provided with the cutoff circuit 72. The cutoff circuit 72 may be any circuit other than the differentiation circuit 73 as long as it is capable of sending a pulse waveform signal to the transistor T1. The control unit 30 does not necessarily have to send an ON signal to the switching unit 40 until the second predetermined time TB has elapsed since the start of power supply.

[0130] The switching unit 40 may not be configured to include the branch circuit 75. The control unit 30 may switch the state of the 5V generation circuit 74 from a supply state to a stopped state without stopping the transmission of an ON signal to the switching unit 40. The trigger switch TS and the push switch PS may be interchanged. A switching unit having a trigger switch TS instead of the push switch PS may be provided separately from the switching unit 40. The battery state detection circuit 82 may be omitted, and the control unit 30 may determine whether or not the battery 32 is present.

[0131] An AC adapter may be used instead of the battery 32. As an example, the AC adapter is connected to an AC power source external to the nail gun 10, converts AC power into DC power (e.g., 12 V DC), and supplies the DC power to the terminals of the connector 18 of the nail gun 10.

[0132] The power supply unit is not limited to the 5V generation circuit 74. It may be a circuit that generates a voltage other than 5V.

[0133] The work machine is not limited to the nail gun 10, but may be a machine that is operated by the rotation of another motor. Another example of a work machine may be a drill used for drilling holes.

[0134] The first predetermined time TA may be set to a time other than 5 minutes or more and 10 minutes or less. Furthermore, even when the push lever 42 remains on, another condition may be set instead of the first predetermined time TA as the condition for the switching unit 40 (control unit 30) to switch the state of the 5V generation circuit 74 from the supply state to the stop state. For example, the switching unit 40 (control unit 30) may be configured to switch the state of the 5V generation circuit 74 from the supply state to the stop state when the amount of drop in the output voltage of the battery 32 while the push lever 42 remains on exceeds a predetermined threshold, or when the voltage value of the output voltage of the battery 32 falls below a predetermined threshold while the push lever 42 is on.

[0135] 10... Nail gun, 11... Housing, 12... Cylinder portion, 13... Injection portion, 14... Motor case, 15... Handle, 16... Mounting portion, 18... Connector, 19... Magazine, 21... Holding plate, 22... Motor, 24... Gear box, 26... Winding gear, 27... First gear, 28... Second gear, 29... Third gear, 30... Control unit, 32... Battery, 33... Striking portion, 34... Plunger, 36... Driver blade, 37... Spring, 38... Counterweight, 40... Switching portion, 41... Operating portion, 42... Push lever, 43... Switch portion, 44... Trigger, 45... First cover cam roller, 46...second cam roller, 47...third cam roller, 48...fourth cam roller, 49...fifth cam roller, 52...top holder, 54...bottom holder, 55...lower bumper, 56...guide bar, 58...guide shaft, 59...upper bumper, 62...first rack, 63...second rack, 64...third rack, 66...latch, 66A...hook, 66B...arm, 68...support shaft, 69...engagement pin, 70...main circuit section, 72...breaker circuit, 73...differentiating circuit, 74...5V generating circuit, 75...branching circuit, 76...SW state detection circuit, 78...delay circuit, 82...power Pond state detection circuit, 84...control signal output circuit, 86...inverter circuit, 88...SW state detection circuit, B...base, C...collector, C1...capacitor, C2...capacitor, D1...diode, D2...diode, D3...diode, D4...diode, E...emitter, G...mating material, K1...path, K2...path, K3...path, K4...path, K5...path, K6...path, K7...path, K8...path, K9...path, K10...path, K11...path, N...nail, PS...push switch, R1...resistor, R2...resistor, R3...resistor, S1...switching element, S2 ...switching element, S3...switching element, T1...transistor, T2...transistor, T3...transistor, T4...transistor, T5...transistor, T6...transistor, t1...time point, t2...time point, t3...time point, t4...time point, t5...time point, t6...time point, tA...time point, tB...time point, TA...first predetermined time, TB...second predetermined time, TC...third predetermined time, TS...trigger switch, VA...voltage, VB...voltage, VC...voltage, VD...voltage, VE...voltage, VF...voltage, VG...voltage, VH...voltage, VI...voltage, VJ...voltage, ZD...diode

Claims

1. A work machine comprising: a motor; a control unit that controls the drive of the motor; a power supply unit capable of switching between a supply state in which power is supplied to the control unit and a stopped state in which power is not supplied to the control unit; and a switching unit that switches the operating state of the power supply unit to either the supply state or the stopped state, wherein the switching unit has a switch unit that is switched between an on state and an off state by operation by an operator, and when the switch unit is switched from the off state to the on state while the power supply unit is in the stopped state, the switching unit switches the state of the power supply unit from the stopped state to the supply state, and even if the switch unit maintains the on state, when a first predetermined time has elapsed, the switching unit switches the state of the power supply unit from the supply state to the stopped state.

2. A work machine as described in claim 1, wherein a first path is provided through which power can be supplied to the power supply unit when a current flows, the switch unit allows current to flow through the first path in the on state and does not allow current to flow through the first path in the off state, the switching unit includes an interrupting circuit connected in series to the first path upstream of the switch unit and capable of interrupting the current in the first path, and when a second predetermined time shorter than the first predetermined time has elapsed since the switch unit was switched from the off state to the on state, the interrupting circuit interrupts the current in the first path.

3. The work machine according to claim 2, wherein the interrupter circuit includes a differential circuit.

4. A work machine as described in claim 2, wherein the control unit sends an on signal to the switching unit so that the switching unit sets the state of the power supply unit to the supply state between the start of power supply from the power supply unit and the elapse of the second specified time.

5. A work machine as described in claim 4, wherein the switching unit includes a branch circuit capable of switching between interruption and non-interruption of a current in a second path electrically connected in parallel with the interrupting circuit, and the branch circuit does not interrupt the current in the second path when the on signal is sent from the control unit, and interrupts the current in the second path when the on signal is not sent from the control unit.

6. A work machine as described in claim 4, wherein the control unit stops sending the on signal to the switching unit if the on state and off state of the switch unit are not switched until the first predetermined time has elapsed after sending the on signal to the switching unit.

7. A work machine as described in any one of claims 1 to 6, comprising: a trigger provided on a handle gripped by an operator; and a push lever provided at a distance from the handle and movable by abutting against an opposing material, wherein the control unit drives the motor when the trigger is turned on with the push lever first turned on, and does not drive the motor even if the push lever is turned on with the trigger first turned on, and the switch unit is turned to the on state when the push lever is turned on.

8. A work machine as described in claim 1, comprising: a main body portion in which the motor, the control portion, the power supply portion and the switching portion are provided; a connection power supply portion connectable to the main body portion and supplying power to the power supply portion and the switching portion when connected to the main body portion; and a detection circuit that detects that the connection power supply portion is connected to the main body portion, wherein the detection circuit sends a detection signal to the control portion when a third predetermined time shorter than the first predetermined time has elapsed since it detected that the connection power supply portion was connected to the main body portion.

9. A work machine having: a motor; a control unit that controls the drive of the motor; a power supply unit capable of switching between a supply state in which power is supplied to the control unit and a stopped state in which power is not supplied to the control unit; and a switch unit that is switched between an on state and an off state by operation of an operator, wherein when the switch unit is switched from the off state to the on state, it switches the power supply unit from the stopped state to the supply state, and the control unit is capable of switching the power supply unit from the supply state to the stopped state even when the switch unit maintains the on state.

Images