Work machine

Abstract

The present invention provides a work machine capable of controlling a wire switching unit at an appropriate timing. The calculation unit (50) is capable of executing connection switching control for switching the coil connection mode of the motor (340) from delta connection to star connection. The calculation unit (50) is configured so as to start the wiring switching control in a state where the number of revolutions of the motor (340) is higher than the number of revolutions of the motor (340) during the star connection (the number of revolutions of the motor (340) during the star connection), and to complete the wiring switching control in a state where the number of revolutions of the motor is equal to or less than the number of revolutions of the motor (340) during the star connection. The calculation unit (50) is configured so as to switch from a state in which the delta connection relay element (32) is turned on and the star connection relay element (33) is turned off to a state in which both the delta connection relay element (32) and the star connection relay element (33) are turned off (a connection cut-off state) when the inverter circuit (64) is in a drive stop state during the connection switching control. And switches from a connection cut-off state to a state in which the delta connection relay element (32) is turned off and the star connection relay element (33) is turned on.

Description

Technical Field

[0001] The invention relates to a working machine. Background Art

[0002] There is known a technology (motor wiring switching technology) that enables driving suitable for work by changing the wiring method of the coils of the motor.

[0003] Patent Document 1 describes an electric tool as a working machine that can switch the connection method of a motor coil according to the type of power source (power source voltage) connected.

[0004] Patent document 2 describes an electric tool as a working machine, in which the winding of the motor is set to a star connection (Y connection), and the number of series connections or parallel connections of the coils in the star connection can be switched according to the work load applied to the motor. Furthermore, it is described that when switching the connection relationship of the winding, a period for repeatedly switching the connection relationship is set to suppress a sudden change in torque or rotation speed.

[0005] Patent Document 3 describes a motor control for an automobile that can switch between a star connection and a delta connection.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-121158

[0009] Patent Document 2: Japanese Patent Application Publication No. 2013-111734

[0010] Patent Document 3: Japanese Patent Laid-Open No. 5-003694 Summary of the invention

[0011] Problems to be solved by the invention

[0012] The present inventors have recognized that there are the following problems when introducing the motor wiring switching technology into a working machine. · Problem 1 ... Provide a working machine with a high working speed while using the motor wiring switching technology. · Problem 2 ... Provide a working machine with high reliability against failure while using the motor wiring switching technology. · Problem 3 ... Provide a working machine with high durability against overload while using the motor wiring switching technology. · Problem 4 ... Provide a working machine that can apply electric braking to the motor while using the motor wiring switching technology.

[0013] An object of the present invention is to solve at least one of the above-mentioned problems 1 to 4.

[0014] Technical means of solving problems

[0015] A certain aspect of the present invention is a working machine. The working machine comprises: a motor including a plurality of windings; a driving unit driving the motor; a wiring switching unit configured to switch between a high-speed wiring state in which the plurality of windings are connected to each other in a manner that provides a high-speed characteristic and a high-torque wiring state in which the plurality of windings are connected to each other in a manner that provides a high-torque characteristic; an operating unit for operating the start and stop of the motor; and a control unit for controlling the driving unit and the wiring switching unit. The working machine is characterized in that the control unit is configured to execute wiring switching control for switching from the high-speed wiring state to the high-torque wiring state, and the wiring switching control is started when the number of revolutions of the motor is greater than the no-load number of revolutions of the high-torque wiring state.

[0016] Another aspect of the present invention is a working machine. The working machine comprises: a motor including a plurality of windings; a driving unit driving the motor; a wiring switching unit configured to be able to switch from one of the high-speed wiring state in which the plurality of windings are connected to each other in a manner that provides a high-speed characteristic and a high-torque wiring state in which the plurality of windings are connected to each other in a manner that provides a high-torque characteristic to another wiring state; an operating unit for operating the start and stop of the motor; and a control unit for controlling the driving unit and the wiring switching unit, wherein the working machine is characterized in that the control unit is configured to be able to perform wiring switching control for switching from one of the wiring states to the other wiring state, and in the wiring switching control, the driving unit is switched to a driving stop state in which the supply of driving power to the motor is stopped, and the wiring switching unit is switched from one of the wiring states to a wiring disconnection state in which the plurality of windings are disconnected from each other.

[0017] Another aspect of the present invention is a working machine. The working machine includes: a motor having a rotor and a stator including a plurality of windings; a wiring switching unit capable of switching the wiring mode of the plurality of windings between a first wiring mode for high rotation and a second wiring mode for high torque; a driving unit having a plurality of switching elements for driving the motor; and a control unit for controlling the driving unit and the wiring switching unit. The working machine is characterized in that the control unit is configured in a first mode to be capable of executing wiring switching control for switching the wiring mode from the first wiring mode to the second wiring mode according to an increase in a working load applied to the motor, and is configured to be capable of not executing an overload protection control for stopping the motor when the working load satisfies an overload protection condition before the wiring switching control, but executing the overload protection control only after the wiring switching control.

[0018] Another aspect of the present invention is a work machine. The work machine includes: a motor having a rotor and a stator including a plurality of windings; a wiring switching unit capable of switching the wiring mode of the plurality of windings between a first wiring mode for high rotation and a second wiring mode for high torque; a drive unit having a plurality of switching elements for driving the motor; a control unit for controlling the drive unit and the wiring switching unit; and a mode selection unit capable of being operated by an operator, wherein the work machine is characterized in that the control unit is configured to be capable of selecting which mode of the first mode and the second mode to drive the motor according to the operator's operation of the mode selection unit, the first mode being configured to be capable of executing wiring switching control for switching the wiring mode from the first wiring mode to the second wiring mode according to an increase in the operating load applied to the motor, and the second mode being configured to maintain the wiring mode at the second wiring mode.

[0019] Another aspect of the present invention is a working machine. The working machine includes: a motor having a plurality of windings driven by power supplied from a power source; a wiring switching unit capable of switching the wiring mode of the plurality of windings of the motor between a first wiring mode for high rotation and a second wiring mode for high torque; a control unit for controlling the motor and the wiring switching unit; a housing for accommodating the motor, the wiring switching unit and the control unit; and a detection unit for detecting a physical quantity that changes due to the driving of the motor or the type of the power source. The working machine is characterized in that the control unit is configured to perform wiring switching control to switch the wiring mode from the first wiring mode to the second wiring mode when a prescribed winding switching condition is satisfied, the detection value includes a working load applied to the motor, and the winding switching condition includes a duration of any working load above a load threshold value that becomes above a time threshold value that varies according to the magnitude of the working load.

[0020] Another aspect of the present invention is a working machine. The working machine includes: a motor having a rotor and a stator including a plurality of windings; a wiring switching unit for switching the wiring of the plurality of windings; a driving unit having a plurality of switching elements for driving the motor; a control unit for controlling the driving unit and the wiring switching unit; and a switch for instructing the start and stop of the motor. The working machine is characterized in that the control unit is configured to control the wiring switching unit so that when the load applied to the motor increases, the wiring is switched from a high rotation mode to a high torque mode, and the control unit is configured to switch to the high torque mode when the switch is disconnected in the high rotation mode to apply electric braking to the motor.

[0021] Another aspect of the present invention is a working machine. The working machine includes: a motor having a rotor and a stator including a plurality of windings; a wiring switching unit for switching the wiring of the plurality of windings; a driving unit having a plurality of switching elements for driving the motor; a control unit for controlling the driving unit and the wiring switching unit; and a switch for instructing the start and stop of the motor. The working machine is characterized in that the control unit is configured to control the wiring switching unit so that when the load applied to the motor increases, the wiring is switched from a high rotation mode to a high torque mode, and the control unit is configured to apply an electric brake to the motor in the state of the high rotation mode to stop the motor when the switch is disconnected in the high rotation mode.

[0022] The present invention can also be expressed as an "electric working machine," "electric tool," "electric equipment," or the like, and such expressions are also effective as aspects of the present invention.

[0023] Effects of the Invention

[0024] According to the present invention, at least one of the above-mentioned problems 1 to 4 can be solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] [ Figure 1 ] is a three-dimensional view of the working machine 1 according to the first embodiment of the present invention as viewed from above.

[0026] [ Figure 2 ] is a three-dimensional view of the working machine 1 as viewed from the lower side.

[0027] [ Figure 3 ] is a front view of the working machine 1.

[0028] [ Figure 4 ]yes Figure 3 CC cross-section diagram.

[0029] [ Figure 5 ] indicates that the cover member 328 is used to cover Figure 4 A cross-sectional view showing a state in which the left portion of the intermediate shell 324 is opened.

[0030] [ Figure 6 ] is a cross-sectional view of the motor 340 of the working machine 1.

[0031] [ Figure 7 ] is an appearance diagram of the operation panel 316 of the working machine 1.

[0032] [ Figure 8 ] is a circuit block diagram of the working machine 1.

[0033] [ Fig. 9] is a simple graph showing the relationship between the torque and the number of revolutions of the motor 340 when the motor 340 is of low rotation specification.

[0034] [ Fig.10 ] is a simple graph showing the relationship between the effective current value and the torque of the motor 340 when the motor 340 is of low rotation specification.

[0035] [ Fig.11 ] is a simple graph showing the relationship between the torque and the number of revolutions of the motor 340 when the motor 340 is of high rotation specification.

[0036] [ Fig.12 ] is a simple graph showing the relationship between the effective current value and the torque of the motor 340 when the motor 340 is of high rotation specification.

[0037] [ Fig.13 ] is a graph showing the relationship between the product torque of the working machine 1 and the sawtooth rotation number.

[0038] [ Fig.14 ](A) is a graph showing an example of the time change of the current flowing in the battery pack 307 of the working machine 1 when the first control is performed to complete the switch from the delta connection to the star connection in a state where the rotation speed of the motor 340 is higher than the no-load rotation speed in the star connection. (B) is a graph showing an example of the time change of the sawtooth rotation speed of the working machine 1 when the first control is performed. (C) is a graph showing an example of the time change of the voltage between the input terminals of the inverter circuit 64 of the working machine 1 when the first control is performed.

[0039] [ Fig.15 ] (A) to (C) are graphs obtained by enlarging the vicinity of the connection switching timing in (A) to (C), respectively. (D) is a graph showing the on / off of the inverter circuit 64 on the same time scale as (A) to (C).

[0040] [ Fig.16 ] (A) is a graph showing an example of the time change of the current flowing in the battery pack 307 of the working machine 1 when the second control is performed to complete the switch from the delta connection to the star connection after the number of revolutions of the motor 340 becomes less than the no-load number of revolutions in the star connection. (B) is a graph showing an example of the time change of the sawtooth number of revolutions of the working machine 1 when the second control is performed. (C) is a graph showing an example of the time change of the voltage between the input terminals of the inverter circuit 64 of the working machine 1 when the second control is performed.

[0041] [ Fig.17 ](A)~(C) are respectively Fig.16(A) to (C) are enlarged diagrams of the wiring switching timing. (D) is based on Fig.17 (A) to (C) are graphs showing on / off of the inverter circuit 64 on the same time scale.

[0042] [ Fig.18 ] is a diagram showing the time variation of the on / off of the delta connection relay element 32 and the star connection relay element 33 when the instructions to turn off the delta connection relay element 32 and turn on the star connection relay element 33 are simultaneously issued in the connection switching control.

[0043] [ Fig.19 ] is a diagram showing the time changes of the on / off of the delta connection relay element 32 and the star connection relay element 33 when a command to turn off the delta connection relay element 32 is issued in the connection switching control and then a command to turn on the star connection relay element 33 is issued after a waiting time.

[0044] [ Fig. 20 ] is a simplified graph showing an example of the temporal variation of the rotation speed of the motor 340 assumed when the third control of completing the connection switching control at the timing when the rotation speed of the motor 340 is reduced to the assumed rotation speed in the star connection is performed.

[0045] [ Fig.21 ] is a simple graph showing an example of the time variation of the actual number of revolutions of the motor 340 when the third control is performed.

[0046] [ Fig. 22 ] is a simplified graph showing an example of the time variation of the actual number of revolutions of the motor 340 when the fourth control is performed to complete the connection switching control before the number of revolutions of the motor 340 decreases to the assumed number of revolutions in the star connection.

[0047] [ Fig.23 ] is a simplified graph showing an example of the time variation of the actual number of revolutions of the motor 340 when the fifth control is performed in which constant speed control is performed in star connection and the connection switching control is completed when the number of revolutions of the motor 340 is reduced to the number of revolutions of the constant speed control in the star connection.

[0048] [ Fig.24 ] is a control flow chart of the working machine 1.

[0049] [ Fig.25 ] is a graph concerning embodiment 2 of the present invention, showing the relationship between the motor torque and the motor speed of the working machine 1 and increasing the pressing load of the working machine 1 on the target material in each of the automatic switching mode and the viscous mode.

[0050] [ Fig.26 ] is a graph showing the relationship between the sawtooth torque and the sawtooth rotation number of the working machine 1, and is a graph showing the case where the pressing load of the working machine 1 on the workpiece is increased in each of the automatic switching mode and the viscous mode.

[0051] [ Fig. 27 ] is a graph showing the relationship between the sawtooth torque and the sawtooth rotation number of the working machine 1, and is a graph showing the case where the pressing load of the working machine 1 on the workpiece is increased and then reduced in the automatic switching mode.

[0052] [ Fig.28 ] is a graph showing the relationship between the effective value of the battery current of the working machine 1 and the number of sawtooth revolutions, and is a graph showing the case where the pressing load of the working machine 1 on the workpiece is increased and then decreased in the automatic switching mode.

[0053] [ Fig.29 ] is a control flow chart of the automatic switching mode of the working machine 1, and is a control flow chart for increasing the pressing load of the working machine 1 on the target material after the trigger switch 306 is turned on.

[0054] [ Fig.30 ] is a control flow chart of the automatic switching mode of the working machine 1, and is a control flow chart when the pressing load of the working machine 1 on the object material is reduced during operation under star connection.

[0055] [ Fig.31 ] is a control flow chart of the sticky mode of the working machine 1.

[0056] [ Fig.32 ] is a flow chart of the overload protection control of the working machine 1.

[0057] [ Fig.33 ] is a flowchart of protection control based on a discharge stop signal from the battery pack 307 of the working machine 1.

[0058] [ Fig.34 ] is a graph showing the time variation of the battery current and the sawtooth rotation number in the automatic switching mode of the working machine 1 and when the pressing load of the working machine 1 on the workpiece is set to 110N or less.

[0059] [ Fig.35 ] is to Fig.34 This is a diagram that enlarges the area around the switching timing of the wiring method.

[0060] [ Fig.36 ] is a graph showing the time variation of the battery current and the sawtooth rotation number in the automatic switching mode of the working machine 1 and when the pressing load of the working machine 1 on the workpiece is suddenly increased to more than 120N during operation under the delta connection.

[0061] [ Fig.37] is to Fig.36 This is a diagram that enlarges the area around the switching timing of the wiring method.

[0062] [ Fig.38 ] is a graph showing the time variation of the battery current and the sawtooth rotation number in the sticky mode of the working machine 1 when the pressing load of the working machine 1 on the workpiece is set to 110N or less.

[0063] [ Fig.39 ] is a graph showing the time variation of the battery current and the sawtooth rotation number in the viscous mode of the working machine 1 and when the pressing load of the working machine 1 on the workpiece is suddenly increased to more than 120N during operation under the delta connection.

[0064] [ Fig.40 ] is a circuit block diagram of the working machine 2 according to embodiment 3 of the present invention.

[0065] [ Fig.41 ] is a graph showing the time variation of the battery current and the sawtooth rotation number in the automatic switching mode of the working machine 2 and when the pressing load of the working machine 1 on the workpiece is suddenly increased to more than 120N during operation in the delta connection.

[0066] [ Fig.42 ] is a circuit block diagram of the working machine 3 according to embodiment 4 of the present invention.

[0067] [ Fig.43 ] (A) is a table summarizing the winding switching conditions in the working machine 3. (B) is a table summarizing the overcurrent protection operating conditions in the working machine 3.

[0068] [ Fig.44 ] is to indicate Fig.43 (A) and (B) are graphs showing the relationship between the current range and the time threshold.

[0069] [ Fig.45 ] (A) is a table summarizing the winding switching conditions when the circuit of the working machine 3 is at a low temperature. (B) is a table summarizing the winding switching conditions when the circuit of the working machine 3 is at a high temperature.

[0070] [ Fig.46 ] is to indicate Fig.45 (A) and (B) are graphs showing the relationship between the current range and the time threshold.

[0071] [ Fig.47 ] (A) is a table summarizing the winding switching conditions when the rated capacity of the battery pack 307 of the working machine 3 is 2.5 Ah (low capacity). (B) is a table summarizing the winding switching conditions when the rated capacity of the battery pack 307 is 4.0 Ah (high capacity).

[0072] [ Fig.48 ] is to indicate Fig.47 (A) and (B) are graphs showing the relationship between the current range and the time threshold.

[0073] [ Fig.49 ] is a graph showing the relationship between the current range and the time threshold under various conditions of winding switching conditions and overcurrent protection working conditions for an operating machine according to embodiment 5 of the present invention.

[0074] [ Fig.50 ] is a circuit block diagram of the working machine 4 according to embodiment 6 of the present invention.

[0075] [ Fig.51 ] is a flow chart showing a first control example of the working machine 4.

[0076] [ Fig.52 ] (A) is a flowchart showing a second control example of the working machine 4. (B) is a flowchart showing a third control example of the working machine 4. (C) is a flowchart showing a fourth control example of the working machine 4.

[0077] [ Fig.53 ] is a timing diagram of the first operation example of the working machine 4, and is a timing diagram including the action of switching the coil connection from a delta connection for high rotation use to a Y connection for high torque use according to the increase in the working load.

[0078] [ Fig.54 ] is a timing diagram of the second operation example of the working machine 4, and includes Fig.51 The timing diagram of the actions corresponding to the control of S9 to S17.

[0079] [ Fig.55 ] is a timing diagram of the third operation example of the working machine 4.

[0080] [ Fig.56 ] is a timing chart of the fourth operation example of the working machine 4, and is a timing chart including actions corresponding to the control of S9 to S61 of (B).

[0081] [ Fig.57 ] is a timing diagram of the fifth operation example of the working machine 4, and is a timing diagram including actions corresponding to the control of S9 and S71 of (C).

[0082] [ Fig.58 ] is a three-dimensional view of the working machine 5 according to the seventh embodiment of the present invention as viewed from above.

[0083] [ Fig.59 ] is a three-dimensional view in which a part of the housing 1320 of the working machine 5 is removed and observed from the upper side.

[0084] [ Fig.60 ] is a front view of the working machine 5.

[0085] [ Fig.61 ] is a side view in which a part of the housing 1320 of the working machine 5 is removed and observed from the side.

[0086] [ Fig.62 ] means in Fig.59 1 is a perspective view showing a state where the motor housing 1321 and the control substrate 1311 are removed. DETAILED DESCRIPTION

[0087] (Implementation Method 1) Figure 1 to Figure 24 This invention relates to the working machine 1 according to the first embodiment of the present invention. Figure 3 and Figure 4 , defines mutually orthogonal front-back, up-down, left-right directions in the working machine 1. The left-right direction is a direction parallel to the axial direction of the motor shaft 341 of the working machine 1. The working machine 1 is a portable circular saw. The working machine 1 includes a housing 320.

[0088] The housing 320 is, for example, a resin molded body, and includes a motor housing 321 that accommodates the motor 340 and the like, a handle housing 322 that is gripped by an operator, a battery mounting portion 323 , and an intermediate housing 324 .

[0089] The motor housing 321 is a cylindrical portion whose central axis is substantially parallel to the left-right direction. The handle housing 322 extends obliquely in the front-back and up-down directions above the right portion of the motor housing 321. A trigger switch 306 as an operating portion for the user to instruct the start and stop of the motor 340 is provided at the upper end of the handle housing 322.

[0090] A metal gear box (saw cover) 325 is connected to the left side of the handle housing 322. The gear box 325 accommodates a speed reduction mechanism (not shown) and covers the upper half of the saw teeth 309 as the front end tool.

[0091] The battery installation part 323 is connected to the left from the rear end of the handle housing 322, and the battery pack 307 can be installed in a detachable manner. The working machine 1 uses the battery pack 307 as a power source and operates using the power of the battery pack 307. The working machine 1 has an operation panel 316 on the upper surface of the battery installation part 323. The user switches the operation mode of the working machine 1 through the operation panel 316.

[0092] The intermediate housing 324 is located behind the motor housing 321 , to the side (right) of the battery mounting portion 323 and below the handle housing 322 .

[0093] The working machine 1 includes a motor 340 inside a motor housing 321 . The rotation of the motor 340 is decelerated by a deceleration mechanism in a gear box 325 and is transmitted to the saw teeth 309 .

[0094] Motor 340 is an inner rotor type brushless motor. Figure 6 As shown, the motor 340 includes a motor shaft 341 (output shaft), a rotor core 342 , a rotor magnet 343 (permanent magnet), a stator core 344 and a stator coil 345 .

[0095] The rotor core 342 is disposed around the motor shaft 341 and rotates integrally with the motor shaft 341 relative to the stator core 344. Four rotor magnets 343 are inserted and held in the rotor core 342 at 90-degree intervals in the circumferential direction. The rotor core 342 and the rotor magnets 343 constitute the rotor of the motor 340.

[0096] The stator core 344 is provided so as to surround the outer circumference of the rotor core 342. The stator core 344 includes a cylindrical (annular) yoke portion 346 and six teeth 347 (tooth portions) protruding radially inward from the yoke portion 346. A stator coil 345 is provided on each tooth 347. Each tooth 347 forms a winding slot. The stator core 344 and the stator coil 345 constitute a stator of the motor 340. The stator coil 345 constitutes a plurality of windings of the motor 340.

[0097] The working machine 1 has a control substrate 311 ( Figure 5 ) and multiple battery connection terminals 327 ( Figure 2 The plurality of battery connection terminals 327 face the lower side of the battery mounting portion 323. The plurality of battery connection terminals 327 contact and are electrically connected to the terminals of the battery pack 307 mounted on the battery mounting portion 323.

[0098] like Figure 4 As shown, the working machine 1 has a relay substrate 30 inside the intermediate housing 324. The relay substrate 30 is equipped with a plurality of relay elements 31. The plurality of relay elements 31 constitute a relay unit. The plurality of relay elements 31 are an example of a wiring switching unit, which is a wiring switching unit capable of switching a wiring method of a stator coil 345 (hereinafter referred to as a "coil wiring method") between a first wiring method for high rotation and a second wiring method for high torque, that is, a wiring switching unit capable of switching a high-speed wiring state in which a plurality of windings are interconnected in a manner that has a characteristic that the number of revolutions is higher than other characteristics, i.e., a high-speed wiring state, and a high-torque wiring state in which a plurality of windings are interconnected in a manner that has a characteristic that the number of revolutions is higher than other characteristics, i.e., a high-speed wiring state, and a high-torque wiring state in which a plurality of windings are interconnected in a manner that has a characteristic that the torque is higher than other characteristics, i.e., a high-torque wiring state.

[0099] The relay substrate 30 is mounted on the intermediate housing 324 by means of screws or the like. The intermediate housing 324 opens to the left. The opening is covered by the battery pack 307 mounted on the battery mounting portion 323. Figure 5As shown, a cover member 328 is mounted on the opening by screws or latches, and the opening is covered with the cover member 328, thereby achieving fall-off prevention, waterproofing or dustproofing of the relay substrate 30.

[0100] like Figure 7 As shown, an operation mode switching switch 312 , an operation mode display light emitting diode (LED) 313 , a light mode switching switch 314 , a light mode display LED 315 , and a light mode display LED 317 are provided on the operation panel 316 .

[0101] The operation mode switching switch 312 is an operation mode switching unit (mode selection unit) that enables the operator to switch the operation mode of the work machine 1 between the automatic switching mode (first mode) and the sticky mode (second mode). The operation mode display LED 313 is an operation mode display unit that displays the current operation mode, for example, it is off in the automatic switching mode and lit in the sticky mode.

[0102] The light mode switching switch 314 is a light mode switching unit that allows the operator to switch the light mode of the work machine 1. The light modes include, for example, a constant lighting mode and a trigger operation lighting mode that lights only when the trigger switch 306 is pulled down. The light mode display LED 315 lights up in the case of the trigger operation lighting mode, and turns off in the constant lighting mode. The light mode display LED 317 lights up in the constant lighting mode, and turns off in the trigger operation lighting mode.

[0103] Figure 8 1 is a circuit block diagram of the working machine 1.

[0104] The battery pack 307 includes a battery cell 67 and a protection integrated circuit (IC) 68. The protection IC 68 functions as a battery-side control unit, and outputs a discharge stop signal (LD signal) if the discharge current from the battery cell 67 exceeds the battery-side overcurrent protection threshold.

[0105] The inverter circuit 64 includes six switching elements connected in a three-phase bridge manner, and is a driving unit that drives the motor 340. Each switching element of the inverter circuit 64 is an example of a heating element constituting the working machine 1. The inverter circuit 64 is provided between the output terminals of the battery pack 307. The detection resistor 65 is provided in the path of the current (hereinafter referred to as "motor current") flowing in the stator coil 345. The inverter circuit 64 is mounted on the control substrate 311.

[0106] The control power supply circuit 51 converts the output voltage of the battery pack 307 into a power supply voltage of the operation unit 50, etc., and supplies it to the operation unit 50, etc. The current detection circuit 52 detects the motor current by detecting the voltage across the resistor 65, and sends it to the operation unit 50 as a control unit. The switch operation detection circuit 53 detects the operation of the trigger switch 306 and sends it to the operation unit 50. The battery type detection circuit 54 detects the type (rated voltage or rated capacity, etc.) of the battery pack 307 by the voltage of the identification terminal (not shown) of the battery pack 307, and sends it to the operation unit 50. The battery type detection circuit 54 constitutes a detection unit that detects the capacity of the power supply. The voltage detection circuit 55 detects the output voltage of the battery pack 307 (hereinafter referred to as "battery voltage") and sends it to the operation unit 50.

[0107] The LD detection circuit 66 detects a discharge stop signal (LD signal) from the battery pack 307 and sends the signal to the calculation unit 50 . The control power supply circuit 51 and other circuits and the calculation unit 50 are mounted on the control substrate 311 .

[0108] The control signal circuit 56 outputs a control signal for controlling the on / off of each switching element of the inverter circuit 64 according to the control output of the operation unit 50. The rotation position detection circuit 57 detects the rotation position of the motor 340 through the output signal of the Hall IC (magnetic sensor) 63 provided near the rotor magnet 343, and sends it to the operation unit 50. The number of revolutions detection circuit 58 detects the number of revolutions of the motor 340 (hereinafter referred to as "motor number of revolutions") through the output signal of the rotation position detection circuit 57, and sends it to the operation unit 50. In addition, in this specification, "number of revolutions" means the number of revolutions per unit time, which means the rotation speed. The operation mode detection circuit 59 detects the operation mode (operation mode) corresponding to the user's operation of the operation mode switching switch 312, and sends it to the operation unit 50. The lighting LED drive circuit 61 drives the lighting LED 62 according to the control of the operation unit 50.

[0109] The operation unit 50 includes a microcontroller and the like, and is a control unit that controls the overall operation of the working machine 1. The operation unit 50 controls the drive of the inverter circuit 64 via the control signal circuit 56 (for example, performs pulse width modulation (PWM) control on each switching element of the inverter circuit 64), and controls the drive current supplied to the stator coil 345. The operation unit 50 can detect the torque of the motor 340 (hereinafter referred to as "motor torque"), that is, the load applied to the motor 340 (hereinafter referred to as "working load") through the motor current.

[0110] The operation unit 50 controls the relay element 31 to switch the coil connection mode (coil connection) between a delta connection for high rotation and a star connection (Y connection) for high torque. The state where the coil connection mode is a delta connection corresponds to a high rotation speed connection state, and the state where the coil connection mode is a star connection corresponds to a high torque connection state. The operation unit 50 can perform connection switching control to switch the coil connection mode from a delta connection to a star connection, that is, to switch from a high rotation speed connection state to a high torque connection state.

[0111] The plurality of relay elements 31 include three delta connection relay elements 32 as the first relay unit and three star connection relay elements 33 as the second relay unit. The operation unit 50 sets the coil connection mode to delta connection by turning on the delta connection relay element 32 and turning off the star connection relay element 33, and sets the coil connection mode to star connection by turning on the star connection relay element 33 and turning off the delta connection relay element 32. In addition, there may be two star connection relay elements 33. That is, one of the three star connection relay elements 33 may be replaced with a short circuit.

[0112] The operation mode (control mode by the calculation unit 50 ) of the working machine 1 includes an automatic switching mode (first mode) and a viscous mode (second mode). As described above, the operator can select the operation mode using the operation mode switching switch 312 .

[0113] The operation unit 50 switches the coil connection mode from the delta connection (first connection mode) for high rotation speed to the star connection (second connection mode) for high torque in the automatic switching mode (first mode) according to the increase of the operating load. That is, the operation unit 50 is configured to control the plurality of relay elements 31 in the automatic switching mode so that the coil connection mode is switched from the high rotation mode to the high torque mode when the operating load increases.

[0114] In the viscous mode (second mode), the operation unit 50 does not switch the coil connection method from high rotation to high torque regardless of the increase in the operating load. Specifically, in the viscous mode, the operation unit 50 fixes the coil connection method to the star connection for high torque use, and does not switch the coil connection method regardless of the operating load. The operating load is the load applied to the motor 340 due to the operation, that is, the load applied to the motor 340 by pressing the rotating saw teeth 309 to the object material, and does not include a temporary high load accompanying the start of the motor 340. That is, the operation unit 50 maintains the connection method at the second connection method in the viscous mode.

[0115] Hereinafter, the automatic switching mode will be described in this embodiment.

[0116] Fig. 9 The graph shows the relationship between the motor torque and the motor rotation speed, with the horizontal axis being the motor torque and the vertical axis being the motor rotation speed, and shows the relationship between the motor torque and the motor rotation speed when the motor 340 is of a low rotation specification. Fig.10 The graph shows the relationship between the effective value of the motor current and the motor torque. When the motor 340 is of low rotation specification, the intersection of the characteristic line of the delta connection and the characteristic line of the star connection ( Fig. 9 The switch from delta connection to star connection is performed at the winding switching point in the intersection. Since the effective value of the motor current in the torque at the intersection is less than the threshold of the overcurrent protection, the overcurrent protection does not work before the connection is switched. However, there is a problem of slow operation speed due to the low motor speed.

[0117] Fig.11 and Fig.12 They respectively represent the relationship between the motor torque and the number of motor revolutions when the motor 340 is made into a specification suitable for high rotation, i.e., a high rotation specification, and the relationship between the effective value of the motor current and the motor torque. By reducing the number of turns of the stator coil 345, etc., the motor 340 can be made into a high rotation specification, thereby improving the operating speed. On the other hand, in the case of a high rotation specification, if the torque is the same, the motor current increases significantly compared to the case of a low rotation specification, and the effective value of the motor current at the intersection of the characteristic line of the delta connection and the characteristic line of the star connection is greater than the threshold value of the overcurrent protection. Therefore, in the case of a high rotation specification, it is difficult to obtain the effective value of the motor current at the intersection of the characteristic line of the delta connection and the characteristic line of the star connection ( Fig.11 The switch from the delta connection to the star connection is performed at the switching point 2 in the figure. Therefore, in the case of high rotation specifications, the switch from the delta connection to the star connection is performed at the switching point 1 where the torque is lower than the intersection of the characteristic line of the delta connection and the characteristic line of the star connection. The time from the start to the completion of the connection switching is very short, for example, less than 100 ms. From the perspective of the work feel, it is important to make the switching timing of the on / off of the relay element 31 or the inverter circuit 64 appropriate during the time. This will be described later.

[0118] Fig.13 The graph shows the relationship between the product torque of the working machine 1 (torque of the saw teeth 309) and the number of rotations of the saw teeth 309 (number of saw teeth rotations) as the vertical axis. Fig.13This is an example of constant speed control of the motor 340 in the low torque region, in which the sawtooth speed becomes constant. A graph showing the relationship between the torque and the speed of such a front end tool can be obtained by the following experiment. That is, while the output shaft of the front end tool is connected to a load device, the speed of the output shaft and the torque of the output shaft are measured while the load torque generated by the load device is gradually increased from a zero state. The result is output as a graph with the torque of the output shaft as the horizontal axis and the speed of the output shaft as the vertical axis. In addition, in many working machines, since the motor is connected to the output shaft holding the front end tool via a reduction mechanism, the torque and speed of the motor can be calculated based on the torque and speed of the output shaft holding the front end tool and the reduction ratio of the reduction mechanism. Therefore, through the same experiment as described above, a graph showing the relationship between the torque and speed of the motor can also be obtained.

[0119] Fig.13 The no-load rotation speed of the sawtooth 309 in the star connection is the no-load rotation speed of the sawtooth 309 when the inverter circuit 64 is controlled at a duty ratio of 100% in the no-load state and the star connection state. Fig.13 The sawtooth speed (about 3,000 min-1 as an example) is shown at the intersection of the extended line (approximate curve) of the characteristic line of the star connection in FIG. 1 and the straight line with a torque of 0. -1 ). The motor speed corresponding to the no-load speed of the sawtooth 309 in the star connection is the no-load speed of the motor 340 in the star connection (hereinafter referred to as "no-load speed in the star connection"). In the working machine 1, the operation unit 50 starts the connection switching control of switching the coil connection method from the delta connection to the star connection when the coil connection method is the delta connection and the motor speed is higher than the no-load speed in the star connection. As a result, compared with the case where the connection switching control is started in the state where the motor speed is lower than the no-load speed in the star connection, the motor 340 can be set to a higher rotation specification, and the situation where the motor 340 stops due to overcurrent protection before starting the connection switching control can be suppressed. In order to increase the working speed in the state where the load torque increases, it is ideal to complete the started connection switching control as soon as possible and restart the motor drive. Therefore, in the case where the connection switching control is started in the state where the motor speed is higher than the no-load speed in the star connection, from the perspective of increasing the working speed, it is natural to complete the connection switching control in the state where the motor speed is higher than the no-load speed in the star connection. However, during the period when the operation unit 50 performs the wiring switching control, the motor 340 idles and generates a reverse voltage. From the perspective of suppressing the reverse voltage of the motor 340, it is important to determine whether the motor speed when the wiring switching control is completed is less than the no-load speed when the star connection is performed. This point will be described below.

[0120] Fig.14(A) to (C) are graphs respectively showing examples of the time variations of the current flowing in the battery pack 307 (hereinafter referred to as "battery current"), the sawtooth speed, and the voltage between the input terminals of the inverter circuit 64 (hereinafter referred to as "inverter voltage") when the first control is performed to complete the switch from the delta connection to the star connection in a no-load state when the motor speed is higher than the star connection speed. Fig.15 (A)~(C) are respectively Fig.14 Graphs showing the enlarged view of the wiring switching timing and the vicinity in (A) to (C). Fig.15 (D) is with Fig.15 (A) to (C) are graphs showing on / off states of the inverter circuit 64 on the same time scale.

[0121] In the case of the first control, the connection switching control is completed in a state where the motor speed is higher than the no-load speed in the star connection, and the current path of the star connection is connected. Therefore, at the timing of the completion of the connection switching control, the inverter voltage rises sharply due to the reverse voltage of the motor 340, and exceeds the allowable voltage between the positive and negative electrodes of the battery pack 307 (for example, 43V in the case of a rated voltage of 36V) or the allowable voltage (for example, 48V) of each switching element of the inverter circuit 64. Therefore, the first control has room for improvement in terms of suppressing the reverse voltage of the motor 340.

[0122] Fig.16 (A) to (C) are graphs showing examples of time changes in battery current, sawtooth speed, and inverter voltage when the second control is performed to complete the switch from delta connection to star connection after the motor speed becomes equal to or lower than the no-load speed in star connection. Fig.17 (A)~(C) are respectively Fig.16 Graphs showing the enlarged view of the wiring switching timing and the vicinity in (A) to (C). Fig.17 (D) is with Fig.17 (A) to (C) are graphs showing on / off states of the inverter circuit 64 on the same time scale.

[0123] In the case of the second control, the connection switching control is completed when the motor speed is less than the no-load speed in the star connection, and the current path of the star connection is turned on. Therefore, at the completion timing of the connection switching control, the inverter voltage is suppressed from rising due to the reverse voltage of the motor 340. Therefore, the risk of the inverter voltage exceeding the allowable voltage between the positive and negative electrodes of the battery pack 307 or the allowable voltage of each switching element of the inverter circuit 64 is suppressed.

[0124] Fig.18(A) to (C) are diagrams showing the time changes of the on / off of the delta connection relay element 32 and the star connection relay element 33 when the instructions to turn off the delta connection relay element 32 and turn on the star connection relay element 33 are issued simultaneously in the connection switching control.

[0125] When the instructions to turn off the delta connection relay element 32 and to turn on the star connection relay element 33 are issued simultaneously, Fig.18 (A) (the state where the delta connection relay element 32 is turned on and the star connection relay element 33 is turned off) to Fig.18 (C) (the state where the delta connection relay element 32 is off and the star connection relay element 33 is on), it is easy to temporarily generate the following Fig.18 (B) shows a short-circuited wiring state (a state where both the delta connection relay element 32 and the star connection relay element 33 are turned on).

[0126] In the short-circuited state, due to the reverse voltage generated in the stator coil 345, a braking current flows in the closed loop including the delta connection relay element 32, the star connection relay element 33, and the stator coil 345, and the motor speed is unnecessarily reduced. In addition, since a braking current flows in the star connection relay element 33 at the moment when the star connection relay element 33 is turned on, the risk of damage to the star connection relay element 33 is high. The control for solving this problem is shown in Fig.19 (A)~(C)

[0127] Fig.19 (A) to (C) are diagrams showing the time changes of the on / off of the delta connection relay element 32 and the star connection relay element 33 when a command to turn off the delta connection relay element 32 is issued in the connection switching control and then a command to turn on the star connection relay element 33 is issued after a waiting time.

[0128] When a command to turn off the delta connection relay element 32 is issued and a command to turn on the star connection relay element 33 is issued after a waiting time, Fig.19 (A) (the state where the delta connection relay element 32 is turned on and the star connection relay element 33 is turned off) to Fig.19 During the state shown in (C) (the state where the delta connection relay element 32 is off and the star connection relay element 33 is on), Fig.19(B) shows a disconnected wiring state (a state in which both the delta connection relay element 32 and the star connection relay element 33 are turned off). The disconnected wiring state corresponds to the disconnected wiring state.

[0129] In the disconnected state, there is no closed loop for the brake current to flow due to the reverse voltage generated in the stator coil 345. Therefore, the risk of a decrease in the motor speed or damage to the star connection relay element 33 is suppressed. The time to the disconnected state is, for example, about 10 ms.

[0130] Fig. 20 This is a simplified graph showing an example of the time change of the motor speed assumed when the workload is increased and an example of the time change of the motor speed assumed when the third control is performed to complete (end) the connection switching control when the motor speed is reduced to the assumed speed in the star connection. The assumed speed is, for example, 9,000 min. -1 , is determined through experiments.

[0131] exist Fig. 20 In the time on the horizontal axis of , the period from time (a) to time (f) represents the period from the start to the end of the wiring switching control. Time (a) is the driving stop time of the inverter circuit 64. The driving stop of the inverter circuit 64 is to disconnect each switching element of the inverter circuit 64 and switch the inverter circuit 64 to a driving stop state in which the supply of driving power to the motor 340 is stopped. Time (b) is the time when the disconnection instruction is sent from the operation unit 50 to the delta connection relay element 32. Time (c) is the time when the delta connection relay element 32 is actually disconnected. Time (d) is the time when the connection instruction is sent from the operation unit 50 to the star connection relay element 33. Time (e) is the time when the star connection relay element 33 is actually connected. Time (f) is the driving restart time of the inverter circuit 64. Figure 21 to Figure 23 The same is true for time (a) to time (f). In addition, the inverter circuit 64 includes a semiconductor switching element, and the response to the drive and stop instructions from the operation unit 50 is faster than that of the relay element, so the time lag from the drive and stop instructions to the response is negligible.

[0132] according to Fig. 20 Assuming that until time (a), the motor speed decreases as the workload increases in the delta connection state, the motor speed decreases sharply during the connection switching control from time (a) to time (f), and after time (f), the motor speed decreases as the workload increases in the star connection state.

[0133] Fig.21is a simplified graph showing an example of the time change of the actual motor speed when the third control is performed. Fig. 20 Different from the assumption, there is a region 2 where the motor speed increases after time (f). The speed change in region 2 will lead to a deterioration in the working feel. For example, when the characteristic line of the motor speed relative to the torque is shifted upward more than assumed due to the deviation of the torque to motor speed characteristics in the star connection of the motor 340, the motor speed in region 2 increases significantly. The deviation of the torque to motor speed characteristics is caused by the deviation of the magnetic force of the rotor magnet 343 or the mechanical loss in the mechanism part. In addition, Fig.21 When an extension line of the characteristic line of the star connection shown in the figure is drawn, the driving of the inverter circuit 64 is restarted at a rotation speed lower than the characteristic line (extension line).

[0134] Fig. 22 This is a simplified graph showing an example of the time change of the actual motor speed when the fourth control is performed to complete (end) the connection switching control before the motor speed decreases to the assumed speed in the star connection. -1 Below (motor speed is 10,000min -1 According to the fourth control, even if the characteristic line of the torque to the motor speed in the star connection of the motor 340 is shifted upward more than expected, the change in the motor speed during the increase after the moment (f) is suppressed compared with the third control, thereby suppressing the deterioration of the working feel. In addition, Fig.23 When an extension line of the characteristic line of the star connection shown in the figure is drawn, the driving of the inverter circuit 64 is restarted at a higher rotation speed than the characteristic line (extension line).

[0135] Fig.23 This is a simplified graph showing an example of the time change of the actual motor speed when the fifth control is performed in which the constant speed control is performed in the star connection and the fifth control of the connection switching control is completed when the motor speed decreases to the speed of the constant speed control in the star connection. According to the fifth control, the motor speed after the connection switching control becomes the set speed of the constant speed control, regardless of the deviation of the torque to motor speed characteristic in the star connection of the motor 340. Therefore, even if the torque to motor speed characteristic line in the star connection of the motor 340 is shifted upward more than expected, the speed change in the rising motor speed after the time (f) is suppressed compared with the third control, thereby suppressing the deterioration of the working feeling.

[0136] Fig.243 is a control flow chart of the working machine 1. When the trigger switch 306 is turned on (S201), the operation unit 50 turns on the delta connection relay element 32 (S203), turns off the star connection relay element 33 (S205), starts driving the inverter circuit 64 (S207), and drives the motor 340 (operates the working machine 1) in a state where the coil connection method is set to the delta connection (S209). If the work load does not exceed the threshold value A (No in S211), the operation unit 50 continues to drive the motor 340 in the delta connection.

[0137] When the operating load exceeds the threshold value A (Yes in S211), the operation unit 50 stops the drive of the inverter circuit 64 (S213) and sends a disconnection signal to the delta connection relay element 32 (S215). As a result, the delta connection relay element 32 becomes disconnected (S217). The operation unit 50 waits until the motor speed becomes less than the no-load speed when the motor is connected in star connection (No in S219). When the motor speed becomes less than the no-load speed when the motor is connected in star connection (Yes in S219), the operation unit 50 sends a connection signal to the star connection relay element 33 (S221). As a result, the star connection relay element 33 becomes connected (S223). The operation unit 50 restarts the drive of the inverter circuit 64 (S225), and drives the motor 340 in the state where the coil connection method is set to the star connection (S227). In the case of the fifth control, S227 becomes a constant speed control.

[0138] This embodiment has the following effects.

[0139] (1) The calculation unit 50 starts the connection switching control for switching the coil connection from the delta connection to the star connection when the motor speed is higher than the no-load speed in the star connection. Therefore, compared with the case where the connection switching control is started when the motor speed is lower than the no-load speed in the star connection, the motor 340 can be set to a high rotation specification and the motor 340 can be prevented from stopping due to overcurrent protection before the start of the connection switching control.

[0140] (2) The calculation unit 50 is configured to complete the connection switching control in the second control when the motor speed is lower than the no-load speed in the star connection. Therefore, compared with the case where the switch from the delta connection to the star connection is completed when the motor speed is higher than the no-load speed in the star connection, the inverter voltage is suppressed from rising due to the reverse voltage of the motor 340 at the completion timing of the connection switching control. Therefore, the risk of the inverter voltage exceeding the allowable voltage between the positive and negative electrodes of the battery pack 307 or the allowable voltage of each switching element of the inverter circuit 64, causing a malfunction or damage, is suppressed.

[0141] (3) The calculation unit 50 switches the inverter circuit 64 to the drive stop state and switches the relay element 31 to the drive stop state under the wiring switching control. Fig.19 (B) shows the wiring disconnection state (wiring cut-off state). Therefore, compared with the case where the state where the delta connection relay element 32 is on and the star connection relay element 33 is off (high speed wiring state) is switched to the state where the delta connection relay element 32 is off and the star connection relay element 33 is on (high torque wiring state) without passing through the wiring disconnection state (wiring cut-off state), the Fig.18 The risk of the wiring short-circuit state shown in (B) is suppressed, and the risk of a decrease in the motor rotation speed or damage to the star connection relay element 33 is suppressed.

[0142] (4) The calculation unit 50 is configured to switch from the state in which the delta connection relay element 32 is turned on and the star connection relay element 33 is turned off (high-speed connection state) to the state in which both the delta connection relay element 32 and the star connection relay element 33 are turned off (connection disconnection state) when the inverter circuit 64 is in the drive stop state during the connection switching control. Thus, since the delta connection relay element 32 is turned off in a state in which no current flows in the delta connection relay element 32, the risk of damage to the delta connection relay element 32 is suppressed compared to the case in which the delta connection relay element 32 is turned off in a state in which current flows in the delta connection relay element 32.

[0143] (5) The calculation unit 50 is configured to switch from a state where both the delta connection relay element 32 and the star connection relay element 33 are disconnected (connection disconnection state) to a state where the delta connection relay element 32 is disconnected and the star connection relay element 33 is connected (high torque connection state) when the inverter circuit 64 is in the drive stop state during the connection switching control. As a result, at the moment when the star connection relay element 33 is turned on, no current flows in the star connection relay element 33, and the risk of damage to the star connection relay element 33 is suppressed.

[0144] (Implementation Method 2) Figures 1 to 8 , Figure 25 to Figure 41 This relates to Embodiment 2 of the present invention. Hereinafter, description of the common parts with Embodiment 1 will be appropriately omitted. In this embodiment, the difference between the automatic switching mode and the viscous mode of the working machine 1 will be mainly described.

[0145] Fig.25The graph shows the relationship between the motor torque and the motor rotation speed of the working machine 1 when the pressing load of the working machine 1 on the workpiece (hereinafter referred to as “working machine pressing force”) is increased in each of the automatic switching mode and the viscous mode.

[0146] In the automatic switching mode, the operation unit 50 performs constant speed control within the range of motor torque below 0.4 N·m. Therefore, in the automatic switching mode, even if the pressure of the working machine is increased, as long as the motor torque is within the range below 0.4 N·m, the motor speed can be kept constant even if the motor torque increases. When the motor torque exceeds 0.4 N·m, if the pressure of the working machine is increased, the motor torque increases and the motor speed decreases. In addition, the motor speed decreases significantly before and after the coil connection method is switched from delta connection to star connection. Even in star connection, if the pressure of the working machine is increased, the motor torque will increase and the motor speed will decrease.

[0147] In the viscous mode, there is no constant speed control region, and if the pressing force of the working machine is increased, the motor torque increases and the motor speed decreases.

[0148] Fig.26 The graph shows the relationship between the sawtooth torque (torque of the rotating shaft of the sawtooth 309) and the sawtooth rotation number (rotation number of the sawtooth 309) of the working machine 1, and the case where the pressing force of the working machine is increased in each mode of the automatic switching mode and the sticking mode. In this embodiment, as an example, the reduction ratio based on the reduction mechanism is set to 3.88, the sawtooth rotation number becomes 1 / 3.88 of the motor rotation number, and the sawtooth torque becomes 3.88 times the motor torque.

[0149] Fig. 27 This is a graph showing the relationship between the sawtooth torque and the sawtooth rotation number of the working machine 1, and the case where the working machine pressing force is increased and then reduced in the automatic switching mode. In the automatic switching mode, the sawtooth torque (4 N·m or more) when the coil connection method is switched from the delta connection to the star connection is greater than the sawtooth torque (2 N·m or less) when the coil connection method is switched from the star connection to the delta connection. The reason is to suppress the frequent switching between the delta connection and the star connection.

[0150] Fig.28 This is a graph showing the relationship between the effective value of the battery current of the working machine 1 (effective value of the discharge current of the battery pack 307) and the number of sawtooth revolutions, and is a graph showing the case where the working machine pressing force is increased and then decreases in the automatic switching mode. In the automatic switching mode, when the working machine pressing force is increased and the coil connection method is switched from delta connection to star connection, the effective value of the battery current decreases sharply.

[0151] Fig.29This is a control flowchart of the automatic switching mode of the working machine 1, and is a control flowchart when the working machine pressing force is increased after the trigger switch 306 is turned on.

[0152] When the trigger switch 306 is turned on (S1), the operation unit 50 turns on the delta connection relay element 32 (S3), turns off the star connection relay element 33 (S5), starts driving the inverter circuit 64 (S7), and drives the motor 340 (operates the working machine 1) in a state where the coil connection method is set to the delta connection (S9). If the work load does not exceed the threshold value A (No in S11), the operation unit 50 continues to drive the motor 340 in the delta connection.

[0153] When the workload exceeds the threshold value A (Yes in S11), the operation unit 50 stops the drive of the inverter circuit 64 (S13), sets the delta connection relay element 32 to be off (S15), sets the star connection relay element 33 to be on (S17), restarts the drive of the inverter circuit 64 (S19), and drives the motor 340 in a state where the coil connection method is set to the star connection (S21). The threshold value A corresponds to the first winding switching threshold. The effective value of the motor current corresponding to the threshold value A is, for example, 60A. Stopping the drive of the inverter circuit 64 means turning off all six switch elements constituting the inverter circuit 64.

[0154] Fig.30 This is a control flow chart of the automatic switching mode of the working machine 1 and is a control flow chart when the pressing force of the working machine is reduced during operation in a star connection.

[0155] The calculation unit 50 drives the motor 340 in the star connection ( S25 ), and if the workload is not less than the threshold value B (No in S27 ), the calculation unit 50 continues to drive the motor 340 in the star connection.

[0156] When the workload becomes less than the threshold value B (Yes in S27), the operation unit 50 stops the drive of the inverter circuit 64 (S29), sets the star connection relay element 33 to be off (S31), sets the delta connection relay element 32 to be on (S33), restarts the drive of the inverter circuit 64 (S35), and drives the motor 340 in a state where the coil connection method is set to the delta connection (S37). The threshold value B corresponds to the second winding switching threshold value. The threshold value A is greater than the threshold value B.

[0157] Fig.31This is a control flow chart of the sticky mode of the working machine 1. When the trigger switch 306 is turned on (S41), the operation unit 50 turns off the delta connection relay element 32 (S43), turns on the star connection relay element 33 (S45), starts driving the inverter circuit 64 (S47), and drives the motor 340 in a state where the coil connection method is set to the star connection (S49).

[0158] Fig.32 This is a flowchart of the overload protection control of the working machine 1. The operation unit 50 drives the motor 340 under the star connection (S51). If the working load does not exceed the threshold value C (No in S53), the driving of the motor 340 under the star connection continues. When the working load exceeds the threshold value C (Yes in S53), the operation unit 50 stops the driving of the inverter circuit 64 and stops the motor 340 (S55). The threshold value C corresponds to the overload protection threshold. The effective value of the motor current corresponding to the overload protection threshold is, for example, 90A. The threshold value A is less than the threshold value C, preferably more than 2 / 3 of the threshold value C or equal to the threshold value C.

[0159] Fig.33 This is a flowchart of protection control based on a discharge stop signal from the battery pack 307 of the working machine 1. As a premise of the flowchart, the battery pack 307 outputs a discharge stop signal (LD signal) when its own discharge current exceeds the battery side overcurrent protection threshold.

[0160] The calculation unit 50 drives the motor 340 (S61), and when not receiving the discharge stop signal from the battery pack 307 (No in S63), the calculation unit 50 continues to drive the motor 340. When the calculation unit 50 receives the discharge stop signal from the battery pack 307 (Yes in S63), the drive of the inverter circuit 64 is stopped to stop the motor 340 (S55).

[0161] As described above, when the workload exceeds the threshold value C, the calculation unit 50 stops the motor 340. At this time, when the motor current exceeds the main body side overcurrent protection threshold, the calculation unit 50 determines that the workload exceeds the threshold value C. The battery side overcurrent protection threshold is greater than the main body side overcurrent protection threshold.

[0162] Fig.34 This is a graph showing the time changes of the battery current and the sawtooth rotation number in the automatic switching mode of the working machine 1 when the working machine pressing force is set to 110 N or less. The working machine pressing force of 110 N or less corresponds to the first pressing force. Fig.35 Yes Fig.34 The diagram is enlarged near the switching timing (time t3) of the wiring method in. Fig.34The rate of increase (increase speed) of the battery current before the switching timing of the wiring method in corresponds to the first workload increase rate (increase speed).

[0163] At time t1, the trigger switch 306 is turned on, and no-load operation is performed until time t2. During the period from time t1 to time t2, the saw teeth rotation speed increases. From time t2, the saw teeth 309 are pressed against the wood (object material) to perform the cutting operation.

[0164] After time t2, the pressure of the working machine increases, the battery current increases, and the sawtooth speed decreases. At time t3 when the pressure of the working machine is less than 110N, the working load exceeds the threshold value A, and the coil connection method is switched from delta connection to star connection. As a result, the battery current (the discharge current of the battery pack 307) and the sawtooth speed decrease. Afterwards, the calculation unit 50 is controlled to increase the motor speed toward the target speed, thereby increasing the sawtooth speed. At time t4, the trigger switch 306 becomes disconnected, and the battery current and the sawtooth speed decrease to zero.

[0165] Fig.36 This is a graph showing the time changes of the battery current and the sawtooth rotation number in the automatic switching mode of the working machine 1 when the working machine pressing force is suddenly increased to 120 N or more during operation in a delta connection. The working machine pressing force of 120 N or more corresponds to the second pressing force. Fig.37 Yes Fig.36 The diagram is enlarged near the switching timing (time t13) of the wiring method in the diagram. Fig.36 The rate of increase (increase speed) of the battery current before the switching timing of the wiring method in corresponds to the second workload increase rate (increase speed).

[0166] At time t11, the trigger switch 306 is turned on, and no-load operation is performed until time t12. During the period from time t11 to time t12, the saw teeth rotation speed increases. From time t12, the saw teeth 309 are pressed against the wood (object material) to perform the cutting operation.

[0167] After time t12, the pressure of the work machine increases, the battery current rises, and the sawtooth speed decreases. Before time t13, the pressure of the work machine increases sharply to more than 120N. At time t13, the work load exceeds the threshold A, and the coil connection method is switched from delta connection to star connection. As a result, the battery current and the sawtooth speed decrease. The reduction in the sawtooth speed is greater than when the pressure of the work machine is less than 110N ( Fig.34 , Fig.35). The operation unit 50 then attempts to start the motor 340 through the star connection, but the starting current under the star connection is large because the pressure of the working machine is large. Therefore, the motor current exceeds the main body side overcurrent protection threshold, and at time t14 just after switching to the star connection, the motor 340 stops due to overload protection.

[0168] Fig.38 This is a graph showing the time changes of the battery current and the sawtooth rotation number in the stick mode of the working machine 1 when the working machine pressing force is set to 110N or less.

[0169] At time t21, the trigger switch 306 is turned on, and no-load operation is performed until time t22. During the period from time t21 to time t22, the saw tooth rotation speed increases. From time t22, the saw teeth 309 are pressed against the wood (object material) to perform the cutting operation.

[0170] After time t22, the pressing force of the working machine increases, the battery current increases, and the sawtooth rotation speed decreases. At time t24, the trigger switch 306 is turned off, and the battery current and the sawtooth rotation speed decrease to zero.

[0171] Fig.39 This is a graph showing the time changes of the battery current and the sawtooth rotation number in the viscous mode of the working machine 1 when the working machine pressing force is suddenly increased to 120N or more during the operation in the delta connection.

[0172] At time t31, the trigger switch 306 is turned on, and no-load operation is performed until time t32. During the period from time t31 to time t32, the saw tooth rotation speed increases. From time t32, the saw teeth 309 are pressed against the wood (object material) to perform the cutting operation.

[0173] After time t32, the pressure of the working machine increases, the battery current rises, and the sawtooth speed decreases. The pressure of the working machine increases sharply to more than 120N during the process, but the overload protection function does not work. At time t34, the trigger switch 306 becomes disconnected, and the battery current and the sawtooth speed decrease to zero.

[0174] According to this embodiment, the following effects can be achieved.

[0175] (1) The calculation unit 50 is configured to be able to execute an automatic switching mode (first mode) in which the coil connection method is switched from a delta connection for high rotation to a star connection (Y connection) for high torque according to an increase in the operating load, and a sticky mode (second mode) in which the coil connection method is fixed to the star connection for high torque and the coil connection method is not switched regardless of the operating load. Therefore, unlike the case where there is only a mode in which the coil connection method is switched according to the operating load, the coil connection method can be fixed regardless of the operating load, and the workability is improved.

[0176] (2) The calculation unit 50 is configured such that, in the automatic switching mode, when the working machine 1 is pressed against the object material with a working machine pressing force (first pressing force) of 110N or less to perform the operation, the coil connection method is switched from a delta connection for high rotation to a star connection (Y connection) for high torque according to an increase in the operating load, and when the working machine 1 is pressed against the object material with a working machine pressing force (second pressing force) of 120N or more to perform the operation, the motor 340 is stopped immediately after the coil connection method is switched from a delta connection for high rotation to a star connection (Y connection) for high torque according to an increase in the operating load. Therefore, while high workability is achieved by switching the coil connection method according to the operating load, overload protection of the motor 340 can be appropriately performed.

[0177] (3) The operation unit 50 sets the coil connection method to a star connection for high torque use in the sticky mode. In this way, by setting the coil connection method to high torque use from the beginning, unlike the case where the coil connection method is switched from high rotation to high torque use in the middle, the overload protection function can be suppressed from operating due to the starting current after switching to high torque use. As a result, even if the working machine 1 is pressed against the object material with a working machine pressing force (second pressing force) of more than 120N to perform an operation, the operation of the overload protection function can be suppressed. Therefore, the operability when performing operations such as abruptly increasing the working machine pressing force to more than 120N (for example, rough machining operations) can be improved.

[0178] (4) In the automatic switching mode, when the operating load exceeds the threshold value A (the first winding switching threshold), the operation unit 50 switches the coil connection method from the delta connection for high rotation purposes to the star connection (Y connection) for high torque purposes. In addition, when the operating load exceeds the threshold value C (the overload protection threshold), the operation unit 50 stops the motor 340 through the overload protection function. Here, the threshold value A is set to be less than the threshold value C. Therefore, the overload protection function can be suppressed from operating in the drive of the motor 340 under the delta connection for high rotation purposes, thereby improving the workability. In addition, by setting the threshold value A to more than 2 / 3 of the threshold value C, the area where high rotation can be performed can be increased, thereby improving the workability. The effect can be maximized by making the threshold value A equal to the threshold value C.

[0179] (5) The work machine 1 includes an operation mode switching switch 312, which enables the operator to select the automatic switching mode (first mode) and the sticky mode (second mode) as the operation mode of the work machine 1. Therefore, the operator can freely select the automatic switching mode and the sticky mode according to the form of the work to be performed, and the workability is improved.

[0180] (6) The calculation unit 50 is provided with a rest period in which all six switching elements of the inverter circuit 64 are turned off when the coil connection method is switched. Therefore, it is possible to prevent an unexpected situation from occurring due to the driving of the inverter circuit 64 during the switching of the coil connection method, thereby improving reliability.

[0181] (7) In the automatic switching mode, when the operating load decreases and reaches below the threshold value B (second winding switching threshold) when the coil connection method is set to the star connection (Y connection) for high torque use, the calculation unit 50 switches the coil connection method to the delta connection for high rotation use. Here, the threshold value A (first winding switching threshold) is set to be larger than the threshold value B. In this way, the frequent switching of the coil connection method between the delta connection and the star connection can be suppressed.

[0182] (8) The battery pack 307 outputs a discharge stop signal when its own discharge current exceeds the battery side overcurrent protection threshold, and the operation unit 50 stops the motor 340 when receiving the discharge stop signal from the battery pack 307. On the other hand, when the motor current exceeds the main body side overcurrent protection threshold, the operation unit 50 determines that the work load has reached or exceeded the threshold C and stops the motor 340. Here, the battery side overcurrent protection threshold is greater than the main body side overcurrent protection threshold. Therefore, it basically becomes a relationship that the overload protection function on the main body side operates before the overcurrent protection function of the battery pack 307 operates, and the burden applied to the battery pack 307 can be suppressed.

[0183] (9) The calculation unit 50 is configured to switch from a state in which the delta connection relay element 32 is disconnected and the star connection relay element 33 is connected (high torque connection state) to a state in which both the delta connection relay element 32 and the star connection relay element 33 are disconnected (connection disconnection state) when the inverter circuit 64 is in the drive stop state in connection switching control for switching the coil connection method from the star connection to the delta connection, that is, the connection switching control for switching from the high torque connection state to the high speed connection state. Thus, the star connection relay element 33 is turned off in a state in which no current flows in the star connection relay element 33, and thus the risk of damage to the star connection relay element 33 is suppressed compared to a case in which the star connection relay element 33 is turned off in a state in which current flows in the star connection relay element 33.

[0184] (10) The calculation unit 50 is configured to switch from a state where both the delta connection relay element 32 and the star connection relay element 33 are disconnected (connection disconnection state) to a state where the delta connection relay element 32 is connected and the star connection relay element 33 is disconnected (high speed connection state) when the inverter circuit 64 is in the drive stop state during the connection switching control for switching the coil connection method from the star connection to the delta connection. As a result, at the moment when the delta connection relay element 32 is turned on, no current flows in the delta connection relay element 32, and the risk of damage to the delta connection relay element 32 is suppressed.

[0185] (Implementation method 3) Fig.40 This is a circuit block diagram of the working machine 2 according to Embodiment 3 of the present invention. Fig.40 The circuit structure shown is Figure 8 Compared with the circuit structure shown in the figure, the difference is that two battery packs 307 are provided and connected in series with each other, and the other aspects are the same.

[0186] Fig.41 This is a graph showing the time changes of the battery current and the sawtooth rotation number in the automatic switching mode of the working machine 2 when the working machine pressing force is suddenly increased to 120N or more during the delta connection operation.

[0187] At time t41, the trigger switch 306 is turned on, and no-load operation is performed until time t42. During the period from time t41 to time t42, the saw tooth rotation speed increases. From time t42, the saw teeth 309 are pressed against the wood (object material) to perform the cutting operation.

[0188] After time t42, the pressure of the working machine increases, the battery current increases, and the sawtooth speed decreases. Before time t43, the pressure of the working machine increases sharply to more than 120N. At time t43, the working load exceeds the first winding switching threshold, and the coil connection method is switched from delta connection to star connection. As a result, the battery current and the sawtooth speed decrease. Afterwards, the calculation unit 50 controls the motor speed to increase toward the target speed, thereby increasing the sawtooth speed. At time t44, the trigger switch 306 becomes disconnected, and the battery current and the sawtooth speed decrease to zero.

[0189] In the stated Fig.36 In the example, at time t14 immediately after switching to the star connection, the motor 340 stops due to overload protection. Fig.41 Even if switched to star connection, the motor 340 will not stop due to overload protection. The reason is that compared with the working machine 1, two battery packs 307 are connected in series in the working machine 2, the output voltage is doubled, and the battery current is halved, and the peak value of the starting current after switching to star connection is also halved.

[0190] Thus, according to this embodiment, in addition to the effects of embodiment 2, the starting current after the coil connection method is switched from a delta connection for high rotation purposes to a star connection (Y connection) for high torque purposes in the automatic switching mode can be suppressed, thereby suppressing the operation of the overload protection function and improving operability.

[0191] In Embodiments 2 and 3, the second mode may be a mode in which the coil connection method is fixed to a delta connection for high rotation purposes. In this case, the workability when working at high rotation speed is desired can be improved even at the expense of viscosity at high torque.

[0192] The following structure may also be used: the operator may select the automatic switching mode and the sticking mode through the operation mode switching switch 312, or the operator may automatically switch to the sticking mode by detecting a sharp increase in the pressing force of the operating machine through a sensor such as an acceleration sensor or a current sensor. In addition, the trigger switch 306 may be operated differently from the usual operation, for example, the mode may be switched by operating the trigger switch 306 multiple times in a short period of time, or the mode may be switched by operating an existing switch (the trigger switch 306, the light mode switching switch 314, or the remaining capacity switch operated by the operator to display the remaining capacity of the battery pack) differently from the usual operation. Compared with the case of providing a dedicated switch or sensor, the use of an existing switch can suppress the manufacturing cost.

[0193] As the automatic switching mode, a plurality of modes with different thresholds for switching the coil wiring method may be set.

[0194] The second mode is a mode in which the coil connection method is not switched from high rotation to high torque during the operation after the motor 340 is started. Therefore, the second mode also includes the following control, that is, when the motor 340 is started, that is, when the cutting operation before the substantial operation is started, it is determined that the load of the motor 340 is large and the coil connection method is switched from high rotation to high torque, and the substantial operation is started in the state where the coil connection method is for high torque. In addition, when the overload protection function immediately operates when the coil connection method is switched to high rotation, the control of switching the coil connection method from high torque to high rotation and making it impossible to continue the operation ends the substantial operation in the state where the coil connection method is for high torque, and is included in the second mode.

[0195] (Implementation 4) Figure 1 to Figure 7 , Figures 42 to 48 This relates to the working machine 3 according to the fourth embodiment of the present invention. Hereinafter, description of the common parts with the first embodiment will be appropriately omitted.

[0196] Fig.42 is a circuit block diagram of the working machine 3. Figure 8 different parts or Figure 8 The description will focus on the parts not described in the figure. The protection IC 68 detects the temperature of the battery cell 67 (hereinafter also referred to as "battery temperature") and outputs a battery temperature signal. The detection resistor 65 and the current detection circuit 52 constitute a detection unit (sensor unit) that detects the physical quantity (motor current) that changes due to the driving of the motor 340.

[0197] The battery temperature detection circuit 69 detects the battery temperature signal from the battery pack 307 and sends it to the operation unit 50. The battery temperature detection circuit 69 constitutes a detection unit that detects the physical quantity (battery temperature) that changes due to the drive of the motor 340. The thermistor 70 as a temperature detection element is arranged near the inverter circuit 64, and outputs a circuit temperature signal corresponding to the temperature of each switching element of the inverter circuit 64 (hereinafter referred to as "circuit temperature"). The circuit temperature detection circuit 71 detects the circuit temperature signal from the thermistor 70 and sends it to the operation unit 50. The thermistor 70 and the circuit temperature detection circuit 71 constitute a detection unit (sensor unit) that detects the physical quantity (circuit temperature) that changes due to the drive of the motor 340.

[0198] The calculation unit 50 has the following overcurrent protection function (overload protection function), that is, if Fig.43(B) The overcurrent protection (overload protection) operating condition described later in the figure stops the motor 340 even when the trigger switch 306 is turned on. The computing unit 50 has a temperature protection function that stops the motor 340 even when the trigger switch 306 is turned on if the battery temperature or the circuit temperature exceeds a temperature threshold.

[0199] In the second embodiment described above, as the winding switching condition, the case where the workload exceeds the threshold value A is exemplified ( Fig.29 In the present embodiment, the winding switching condition is determined in more detail. In the control flow of the operation unit 50 when the trigger switch 306 is turned on and the pressure of the working machine is increased in the automatic switching mode, except Fig.29 The S11 replaces the branch that satisfies the winding switching condition, and Fig.29 same.

[0200] (Winding switching conditions and overcurrent protection working conditions) Fig.43 (A) is a table in which the winding switching conditions in the working machine 3 are summarized. Fig.43 (B) is a table in which the overcurrent protection operating conditions in the working machine 3 are summarized. Fig.44 Yes means Fig.43 (A) and (B) show the relationship between the current range and the time threshold, and are graphs showing the relationship between the current range and the time threshold under each of the winding switching condition (solid line) and the overcurrent protection operating condition (dashed line).

[0201] The winding switching condition and the overcurrent protection working condition are respectively represented by a combination of the motor current and its duration. Specifically, in each of the winding switching condition and the overcurrent protection working condition, multiple ranges (hereinafter also referred to as "current ranges") are set for the motor current above the current threshold (here 60A), and a threshold value (hereinafter also referred to as "time threshold") of the duration of the motor current within the current range is set for each current range. The motor current corresponds to the operating load, the current threshold corresponds to the load threshold, and the current range corresponds to the load range. Both the winding switching condition and the overcurrent protection working condition are set so that the time threshold is smaller as the current value is larger in the current range.

[0202] Fig.43 The winding switching condition shown in (A) can be considered as a condition related to a time threshold set according to the detected value of the motor current. That is, the calculation unit 50 determines the current range according to the detected value of the motor current, and determines that the winding switching condition is satisfied when the duration of the motor current is longer than the time threshold corresponding to the current range. In other words, the winding switching condition is that the motor current is within an arbitrary current range for a time threshold corresponding to the current range.

[0203] Fig.43 The current ranges in the winding switching conditions shown in (A) are Fig.43 (B) The current ranges in the overcurrent protection operating conditions are common. Fig.43 The time threshold corresponding to each current range in the winding switching condition shown in (A) is less than Fig.43 (B) shows the time thresholds corresponding to each current range in the overcurrent protection operating condition. That is, the winding switching condition is set so that the coil connection method is switched from delta connection to star connection before the overcurrent protection function is activated and the motor 340 stops. This can prevent the overcurrent protection function from being activated and the motor 340 from being stopped before the coil connection method is switched from delta connection to star connection, thereby improving the workability.

[0204] (Winding switching conditions depending on temperature) Fig.45 (A) is a table that summarizes the winding switching conditions when the circuit temperature of the working machine 3 is low temperature (hereinafter also referred to as "winding switching conditions at low temperature"). Fig.45 (B) is a table that summarizes the winding switching conditions when the circuit temperature of the working machine 3 is high (hereinafter also referred to as “high temperature winding switching conditions”). Fig.46 Yes means Fig.45 (A) and (B) show the relationship between the current range and the time threshold, and are graphs showing the relationship between the current range and the time threshold under each condition of the winding switching condition at low temperature (solid line) and the winding switching condition at high temperature (dashed line).

[0205] The calculation unit 50 determines whether the circuit temperature is low, that is, whether the circuit temperature is below a predetermined temperature, based on the signal from the circuit temperature detection circuit 71. A temperature below the predetermined temperature is an example of a first temperature, and a temperature exceeding the predetermined temperature is an example of a second temperature. Fig.45 (A) shows the table of winding switching conditions at low temperatures. Fig.43 The contents of the table of winding switching conditions shown in (A) are the same.

[0206] Fig.45 The current ranges in the high temperature winding switching conditions shown in (B) are Fig.45 The current ranges in the low temperature winding switching conditions shown in (A) are common. Fig.45 The time threshold corresponding to each current range in the high temperature winding switching condition shown in (B) is less than Fig.45 (A) shows the time thresholds corresponding to each current range in the low temperature winding switching condition. This can prevent the motor 340 from being stopped due to the temperature protection function related to the circuit temperature before the coil connection method is switched from delta connection to star connection, thereby improving workability.

[0207] Fig.45 The winding switching conditions shown in (A) and (B) can be considered to be conditions related to the time threshold set based on the detected value of the motor current and the detected value of the circuit temperature. That is, the calculation unit 50 determines the use of the detected value of the circuit temperature. Fig.45 Which of the winding switching conditions (A) and (B) is selected, and the current range is determined based on the detected value of the motor current. When the duration of the motor current is greater than the time threshold corresponding to the current range, it is determined that the winding switching condition is satisfied. In other words, Fig.45 The winding switching conditions shown in (A) and (B) are that the motor current is in an arbitrary current range for a period of time longer than a threshold value corresponding to the current range and the circuit temperature.

[0208] Fig.45 The low temperature winding switching condition shown in (A) can also be applied as a winding switching condition when the battery temperature is low. Fig.45 The high temperature winding switching condition shown in (B) can also be applied as the winding switching condition when the battery temperature is high. This can prevent the temperature protection function related to the battery temperature from being activated and stopping the motor 340 before the coil connection method is switched from the delta connection to the star connection. The calculation unit 50 determines whether the battery temperature is low, that is, whether the circuit temperature is below a predetermined temperature, based on the signal from the battery temperature detection circuit 69.

[0209] (Winding switching conditions according to battery capacity) Fig.47 (A) is a table that summarizes the winding switching conditions when the rated capacity of the battery pack 307 of the working machine 3 is 2.5 Ah (low capacity) (hereinafter also referred to as “winding switching conditions when the capacity is low”). Fig.47 (B) is a table that summarizes the winding switching conditions when the rated capacity of the battery pack 307 is 4.0 Ah (high capacity) (hereinafter also referred to as "winding switching conditions when the capacity is high"). Fig.48 Yes means Fig.47 (A) and (B) show the relationship between the current range and the time threshold, and are graphs showing the relationship between the current range and the time threshold under each condition of the winding switching condition at low capacity (solid line) and the winding switching condition at high capacity (dashed line).

[0210] The calculation unit 50 determines whether the rated capacity (hereinafter also referred to as "rated capacity") of the battery pack 307 is low capacity, that is, whether the rated capacity is less than a prescribed capacity, based on the signal from the battery type detection circuit 54. The rated capacity exceeding the prescribed capacity is an example of the first capacity, and the rated capacity less than the prescribed capacity is an example of the second capacity. Fig.47 (A) shows the winding switching conditions at low capacity. Fig.43The contents of the table of winding switching conditions shown in (A) are the same.

[0211] Fig.47 (B) The time thresholds and Fig.47 The time thresholds in the winding switching conditions at low capacity shown in (A) are common. Fig.47 The current range and the current range corresponding to each time threshold value in the winding switching condition at high capacity shown in (B) Fig.47 The current value is larger than the current range corresponding to each time threshold value in the winding switching condition at low capacity shown in (A). Therefore, when the rated capacity is large, the temperature rise becomes slower than when the rated capacity is small, if the output current is the same, and this point can be used to perform operations in the delta connection for high rotation purposes until the limit corresponding to the rated capacity, thereby improving the workability.

[0212] Fig.47 The winding switching conditions shown in (A) and (B) can be considered to be conditions related to the time threshold set based on the detected value of the motor current and the detected value of the rated capacity. That is, the calculation unit 50 determines the use of the detected value of the rated capacity. Fig.47 Which of the winding switching conditions (A) and (B) is selected, and the current range is determined based on the detected value of the motor current. When the duration of the motor current is greater than the time threshold corresponding to the current range, it is determined that the winding switching condition is satisfied. In other words, Fig.47 The winding switching conditions shown in (A) and (B) are that the motor current is in an arbitrary current range for a period of time longer than a threshold value corresponding to the current range and the rated capacity.

[0213] This embodiment has the following effects.

[0214] (1) Through Fig.43By setting the winding switching conditions as shown in (A), it is possible to suppress the situation where the temperature protection function operates and the motor 340 stops before the coil connection method is switched from the delta connection (first connection method) to the star connection (second connection method), thereby improving operability. When the coil connection method is switched to the star connection, the motor current becomes smaller, and the temperature rise of components such as the inverter circuit 64 is suppressed, so that the operation of the temperature protection function can be avoided and the operation can be continued, thereby improving operability. As a comparative example, in a structure in which the connection method is switched when the motor current exceeds a threshold value, in the case where an operation is performed in which the motor current does not exceed the threshold value but continues to be close to the threshold value, the temperature protection function operates or the component is damaged in a state where the connection method cannot be switched, and the operation cannot be continued, resulting in poor operability. In the comparative example, when the threshold value is set as low as 50A to avoid being unable to continue the operation, the period during which the operation can be performed using the delta connection (first connection method) becomes shorter, resulting in poor operability. The present embodiment preferably solves the above-mentioned problems in the comparative example.

[0215] (2) Through Fig.43 By setting the relationship between the winding switching condition and the overcurrent protection operating condition as shown in (A) and (B), it is possible to prevent the overcurrent protection function from operating and stopping the motor 340 before the coil connection method is switched from the delta connection to the star connection, thereby improving workability. In addition, before the overcurrent protection function is about to operate, work under the delta connection (first connection method) can be performed, thereby improving workability.

[0216] (3) Through Fig.45 As shown in (A) and (B), the winding switching conditions are set differently when the circuit temperature or the battery temperature is low and when it is high, so that the temperature protection function can be prevented from being activated and stopping the motor 340 before the coil connection method is switched from the delta connection (first connection method) to the star connection (second connection method), and the workability is improved. In addition, the operation under the delta connection (first connection method) can be performed to the limit within the allowable range of the circuit temperature or the battery temperature, and the workability is improved.

[0217] (4) Through Fig.47 As shown in (A) and (B), the winding switching conditions are set differently when the rated capacity of the battery pack 307 is low capacity and when the rated capacity is high, so that operations under delta connection (first connection method) can be performed until the limit corresponding to the rated capacity of the battery pack 307, thereby improving operability.

[0218] (Implementation 5) Fig.49 In relation to the working machine of the fifth embodiment, a graph is provided showing the relationship between the current range and the time threshold in each of the winding switching conditions and the overcurrent protection operation conditions. Fig.44In the example of , the current range is set to be common in the winding switching condition and the overcurrent protection working condition, and the time threshold corresponding to each current range is different. Fig.49 In the example of , the time threshold is set to be common in the winding switching condition and the overcurrent protection operation condition, and the current range corresponding to each time threshold is different. Fig.49 In the example, we can also obtain Fig.44 In addition, the current range and time threshold in the winding switching condition can be set to be smaller than the current range and time threshold in the overcurrent protection working condition.

[0219] Although not shown in the figure, the winding switching condition at low temperature and the winding switching condition at high temperature may be set so that the time threshold is common and the current ranges corresponding to the respective time thresholds are different (the current value of the current range of the winding switching condition at high temperature is smaller than the current range of the winding switching condition at low temperature). In addition, the current range and the time threshold in the winding switching condition at high temperature may be set smaller than the current range and the time threshold in the winding switching condition at low temperature.

[0220] In addition, the winding switching condition at low capacity and the winding switching condition at high capacity may be set so that the current range is common and the time thresholds corresponding to the respective current ranges are different (the time threshold of the winding switching condition at high capacity is larger than the time threshold of the winding switching condition at low capacity). In addition, the current range and the time threshold in the winding switching condition at high capacity may be set larger than the current range and the time threshold in the winding switching condition at low capacity.

[0221] In the fourth and fifth embodiments, the winding switching conditions can be set to three or more conditions according to the circuit temperature or the battery temperature and the rated capacity. In addition, instead of switching the coil connection mode to a delta connection or a star connection, multiple coils in a single phase can be switched to a series connection or a parallel connection. In addition, the threshold values ​​of each embodiment can be combined according to the workload, for example Fig.44 and Fig.49 For example, under the condition of light workload (less than 70A), Fig.44 The threshold value is based on the load condition (above 70A) Fig.49 In addition, when the operating load is small (for example, less than 70A), Fig.44 As shown in the figure, the switching of the wiring method or the overload protection is performed based on both the load threshold and the time threshold. When the load is large (70A or more), the switching of the wiring method or the overload protection is performed only based on the load threshold.

[0222] (Implementation 6) Figure 1 to Figure 7 , Figure 50 to Figure 57 This relates to the working machine 4 according to the sixth embodiment of the present invention. Hereinafter, description of the common parts with the first embodiment will be appropriately omitted.

[0223] Fig.50 is a circuit block diagram of the working machine 4. Figure 8 different parts or Figure 8 The following description will focus on the parts not described in the text.

[0224] The six switching elements constituting the inverter circuit 64 include three upper switching elements 72 on the high potential side and three lower switching elements 73 on the low potential side.

[0225] The control circuit voltage detection circuit 74 detects the output voltage of the control circuit voltage supply circuit 51 and sends it to the calculation unit 50. The display LED drive circuit 75 drives the operation mode display LED 313 or the light mode display LED 315 and the light mode display LED 317 according to the control of the calculation unit 50. The winding switching operation output circuit 76 outputs a control signal for controlling the on / off of the delta connection relay element 32 and the star connection relay element 33 according to the control of the calculation unit 50.

[0226] The three delta connection relay elements 32 correspond to the high rotation side switching unit, and the three star connection relay elements 33 correspond to the high torque side switching unit. The delta connection is an example of a first connection in which a braking current based on the electric brake of the motor 340 flows easily. The star connection is an example of a second connection in which a braking current based on the electric brake of the motor 340 does not flow easily.

[0227] Hereinafter, control when the operation mode is the automatic switching mode will be described.

[0228] (First Control Example) Fig.51 1 is a flowchart showing a first control example of the working machine 4. When activated, the calculation unit 50 turns on the three delta connection relay elements 32 and turns off the three star connection relay elements 33 (S101).

[0229] When the trigger switch 306 is turned off ("maintain trigger off (OFF)" of S103), the operation unit 50 returns to S101. When the trigger switch 306 is turned on ("trigger on (ON)" of S103), the operation unit 50 controls the inverter circuit 64 to drive the motor 340 in a state where the three delta connection relay elements 32 are turned on (high rotation mode) (S105).

[0230] The calculation unit 50 checks whether it is an overload state (high load state) (S107). Here, the overload state is a state where the load is greater than the overload detection threshold (first wiring switching threshold).

[0231] When the overload state is not detected (No in S107), the calculation unit 50 proceeds to S109. When the trigger switch 306 is on ("maintain trigger on" in S109), the calculation unit 50 returns to S105.

[0232] When the trigger switch 306 is turned off ("trigger off" of S109), the operation unit 50 turns off the six switch elements of the inverter circuit 64 (S111), turns off the three delta connection relay elements 32 (S113), turns on the three lower switch elements 73 of the inverter circuit 64 (S115), turns on the three star connection relay elements 33 (S117), and applies electric braking to the motor 340 in the high torque mode (star connection). The lower switch elements 73 turned on in S115 may be one or two. The operation unit 50 continues to perform electric braking until the motor 340 stops ("No" of S119), and returns to S101 when the motor 340 stops ("Yes" of S119).

[0233] Thus, the calculation unit 50 is configured to switch to the high torque mode (star connection) when the trigger switch 306 is turned off in the high rotation mode (delta connection), and apply electric braking to the motor 340 to stop the motor 340. At this time, after the three lower switch elements 73 of the inverter circuit 64 are turned on, the three star connection relay elements 33 are turned on.

[0234] When an overload state is detected ("Yes" in S107), the operation unit 50 sets the six switching elements of the inverter circuit 64 to be disconnected (S121), sets the three delta-connected relay elements 32 to be disconnected (S123), sets the three star-connected relay elements 33 to be connected (S125), and controls the inverter circuit 64 to drive the motor 340 when the three star-connected relay elements 33 are connected (high torque mode) (S127).

[0235] In this manner, the calculation unit 50 is configured to switch to the high torque mode (star connection) when the workload increases in the high rotation mode (delta connection).

[0236] The calculation unit 50 checks whether the motor 340 is in a light load state (S131) ​​while driving the motor 340 in the high torque mode (star connection) (S127). The light load state is a state where the load is below the light load detection threshold (second connection switching threshold). The second connection switching threshold is smaller than the first connection switching threshold used to determine whether the motor is in an overload state.

[0237] When the light load state is not detected ("No" of S131), the operation unit 50 enters S133. When the trigger switch 306 is turned on ("Maintain trigger on" of S133), the operation unit 50 returns to S127. When the trigger switch 306 is turned off ("Trigger off" of S133), the operation unit 50 turns on the three lower switch elements 73 of the inverter circuit 64 (S135) to apply electric braking to the motor 340. The operation unit 50 continues to apply electric braking until the motor 340 stops ("No" of S137), and when the motor 340 stops ("Yes" of S137), it returns to S101. In S135, one or two lower switch elements 73 may be turned on.

[0238] When a light load state is detected ("Yes" in S131), the operation unit 50 sets the six switching elements of the inverter circuit 64 to be disconnected (S139), sets the three star-connected relay elements 33 to be disconnected (S141), sets the three delta-connected relay elements 32 to be connected (S143), and controls the inverter circuit 64 to drive the motor 340 when the three delta-connected relay elements 32 are connected (in the high rotation mode) (S105).

[0239] As described above, the calculation unit 50 is configured to switch to the high rotation mode (delta connection) when the workload decreases in the high torque mode (star connection).

[0240] (Second Control Example) Fig.52 (A) is a flowchart showing a second control example of the working machine 4. The second control example is different from the first control example in the control when the trigger switch 306 is turned off in the high rotation mode (delta connection), and is the same in other respects. The following description will focus on the differences.

[0241] When the trigger switch 306 is turned off ("trigger off" in S109), the operation unit 50 sets the six switch elements of the inverter circuit 64 to be turned off (S144), the three delta connection relay elements 32 to be turned off (S145), the three star connection relay elements 33 to be turned on (S146), the three lower switch elements 73 of the inverter circuit 64 to be turned on (S147), and applies electric braking to the motor 340 in the high torque mode (star connection). The lower switch elements 73 turned on in S147 may be one or two. The operation unit 50 continues to perform electric braking until the motor 340 stops ("No" in S148), and when the motor 340 stops ("Yes" in S148), it returns to S101.

[0242] Thus, the calculation unit 50 is configured to switch to the high torque mode (star connection) when the trigger switch 306 is turned off in the high rotation mode (delta connection), and apply electric braking to the motor 340 to stop the motor 340. At this time, after the three star connection relay elements 33 are turned on, the three lower switch elements 73 of the inverter circuit 64 are turned on.

[0243] (Third Control Example) Fig.52 (B) is a flowchart showing a third control example of the working machine 4. The third control example is different from the first control example in the control when the trigger switch 306 is turned off in the high rotation mode (delta connection), and is the same in other respects. The following description will focus on the differences.

[0244] When the trigger switch 306 is turned off in the high rotation mode (delta connection) ("trigger off" in S109), the operation unit 50 turns on the three lower switch elements 73 of the inverter circuit 64 (S151), and applies electric braking to the motor 340 while maintaining the high rotation mode (delta connection). The operation unit 50 continues the electric braking in S151 until the motor speed decreases to less than the specified speed ("No" in S153). The lower switch elements 73 turned on in S151 may be one or two.

[0245] When the motor speed drops below the specified speed ("Yes" in S153), the operation unit 50 sets the six switch elements of the inverter circuit 64 to be disconnected (S155), sets the three delta connection relay elements 32 to be disconnected (S157), sets the three star connection relay elements 33 to be connected (S159), sets the three lower switch elements 73 of the inverter circuit 64 to be connected (S161), and applies electric braking to the motor 340 in the high torque mode (star connection) to stop the motor 340 ("No" in S163). In S161, one or two lower switch elements 73 can be turned on.

[0246] In this way, the operation unit 50 is configured to apply electric braking to the motor 340 to reduce the motor speed to below the specified speed when the trigger switch 306 becomes disconnected in the high rotation mode (delta connection), and then switch to the high torque mode (star connection) to apply electric braking to the motor 340.

[0247] (Fourth Control Example) Fig.52 (C) is a flowchart showing a fourth control example of the working machine 4. The fourth control example is different from the first control example in the control when the trigger switch 306 is turned off in the high rotation mode (delta connection), and is the same in other respects. The following description will focus on the differences.

[0248] When the trigger switch 306 is turned off in the high rotation mode (delta connection) ("trigger off" in S109), the operation unit 50 turns on the three lower switch elements 73 of the inverter circuit 64 (S171), applies an electric brake to the motor 340 while maintaining the high rotation mode (delta connection), and stops the motor 340 ("No" in S173). In S171, one or two lower switch elements 73 may be turned on.

[0249] (First Operation Example) Fig.53 This is a timing chart of the first operation example of the working machine 4, and includes an operation of switching the coil connection method from a delta connection for high rotation to a star connection for high torque according to an increase in the work load. In the timing chart, the trigger switch 306 is continuously turned on. Fig.53 In FIG. 1 , S1 represents an overload detection threshold, and S2 represents a light load detection threshold.

[0250] Before time T1, the load is light, and the calculation unit 50 drives the motor 340 in the high rotation mode (delta connection). That is, the calculation unit 50 performs commutation control (drive control of the motor 340) based on the inverter circuit 64 in a state where the three delta connection relay elements 32 are turned on and the three star connection relay elements 33 are turned off.

[0251] At time T1, the workload rises to the overload detection threshold value S1, the operation unit 50 detects the overload state, and turns off the six switch elements of the inverter circuit 64. At time T2, the operation unit 50 outputs an off signal for the three delta connection relay elements 32. At the subsequent time T2', the three delta connection relay elements 32 are turned off. The relay element is a contact type, so the time lag from the signal output of the operation unit 50 to the actual switching of the relay element on / off is larger than that of the semiconductor switch element.

[0252] At time T3, the calculation unit 50 outputs an on signal to the three star connection relay elements 33. At the subsequent time T3', the three star connection relay elements 33 are turned on. At time T4, the calculation unit 50 resumes commutation control by the inverter circuit 64 (drive control of the motor 340).

[0253] (Second Operation Example) Fig.54 is a timing chart of the second operation example of the working machine 4, and includes Fig.51 The timing diagram of the actions corresponding to the control of S109 to S117. Fig.54 , S1 represents an overload detection threshold, S2 represents a light load detection threshold, V1 represents a battery voltage, and V2 represents a rated voltage of a switching element of the inverter circuit 64.

[0254] Before time T11, the load is light, and the calculation unit 50 drives the motor 340 in the high rotation mode (delta connection). That is, the calculation unit 50 performs commutation control (drive control of the motor 340) based on the inverter circuit 64 in a state where the three delta connection relay elements 32 are turned on and the three star connection relay elements 33 are turned off.

[0255] At time T11, the trigger switch 306 is turned off, and the calculation unit 50 turns off the six switching elements of the inverter circuit 64. At time T12, the calculation unit 50 outputs an off signal to the three delta connection relay elements 32. At the subsequent time T12', the three delta connection relay elements 32 are turned off.

[0256] At time T13, the operation unit 50 turns on all the lower switch elements 73 of the inverter circuit 64. The lower switch elements 73 that are turned on may be one or two. The operation unit 50 outputs a turn-on signal for the three star connection relay elements 33 at time T14. At the subsequent time T14', the three star connection relay elements 33 are turned on. From time T14', the electric brake starts to take effect, the brake current flows in the stator coil 345, and the speed of reducing the motor speed increases.

[0257] In the second operation example, when the three star connection relay elements 33 are turned on at time T14', the lower switch element 73 of the inverter circuit 64 is already turned on, and a closed loop for the regenerative current to flow is established. Therefore, even if the trigger switch 306 is turned off when the motor speed is close to the no-load speed, the voltage applied to the switch element of the inverter circuit 64 (inter-inverter voltage) will not rise to exceed the battery voltage V1.

[0258] (Third Operation Example) Fig.55This is a timing chart of a third operation example of the working machine 4 . Fig.55 In FIG. 6A , V1 represents the battery voltage, and V2 represents the rated voltage of the switching element of the inverter circuit 64 .

[0259] Before time T21, the load is light, and the operation unit 50 drives the motor 340 in the high rotation mode (delta connection). That is, the operation unit 50 performs commutation control (drive control of the motor 340) based on the inverter circuit 64 in a state where the three delta connection relay elements 32 are turned on and the three star connection relay elements 33 are turned off.

[0260] At time T21, the trigger switch 306 is turned off, and the calculation unit 50 turns off the six switching elements of the inverter circuit 64. At time T22, the calculation unit 50 outputs an off signal to the three delta connection relay elements 32. At the subsequent time T22', the three delta connection relay elements 32 are turned off.

[0261] At time T23, the operation unit 50 outputs an on signal for the three star connection relay elements 33. At the subsequent time T23', the three star connection relay elements 33 are turned on. At time T24, the operation unit 50 turns on all the lower switch elements 73 of the inverter circuit 64. From time T24, the electric brake starts to take effect, the braking current flows in the stator coil 345, and the speed of reducing the motor speed increases.

[0262] In the third operation example, at the time point when the three star connection relay elements 33 are turned on at time T23', all six switch elements of the inverter circuit 64 are turned off, and the closed loop for the regenerative current to flow is not established. In the second operation example, a large regenerative current flows at the moment when the three star connection relay elements 33 are turned on and the closed loop is established, and there is a risk of damage to the three star connection relay elements 33. The third operation example suppresses the risk of damage to the star connection relay elements 33. On the other hand, in the third operation example, the trigger switch 306 is turned off during the driving of the motor 340 in the high rotation mode (delta connection), that is, when the motor speed is high. Therefore, the voltage (inter-inverter voltage) applied to the switch element of the inverter circuit 64 rises to exceed the battery voltage V1, exceeds the rated voltage V2 of the switch element of the inverter circuit 64, and there is a risk of damage to the switch element. The second operation example suppresses the risk of damage to the switch element.

[0263] (Fourth Operation Example) Fig.56 is a timing chart of the fourth operation example of the working machine 4, and includes Fig.52 (B) is a timing chart of operations corresponding to the control of S109 to S161. Fig.56In FIG. 1 , S1 represents an overload detection threshold, and S2 represents a light load detection threshold.

[0264] Before time T31, the load is light, and the operation unit 50 drives the motor 340 in the high rotation mode (delta connection). That is, the operation unit 50 performs commutation control (drive control of the motor 340) based on the inverter circuit 64 in a state where the three delta connection relay elements 32 are turned on and the three star connection relay elements 33 are turned off.

[0265] At time T31, the trigger switch 306 is turned off, and the calculation unit 50 turns on all the lower switching elements 73 of the inverter circuit 64. From time T31, the electric brake takes effect, and the braking current flows through the stator coil 345, and the speed of reducing the motor speed increases.

[0266] At time T32, the motor speed decreases to below the specified speed (speed threshold), and the operation unit 50 turns off the six switch elements of the inverter circuit 64. Here, the electric brake is temporarily stopped. The operation unit 50 detects that the motor speed decreases to below the specified speed, and outputs a disconnection signal for the three delta connection relay elements 32 at time T33. At the subsequent time T33', the three delta connection relay elements 32 are turned off.

[0267] At time T34, the operation unit 50 outputs a turn-on signal for the three star connection relay elements 33. At the subsequent time T34', the three star connection relay elements 33 are turned on. At time T35, the operation unit 50 turns on all the lower switch elements 73 of the inverter circuit 64. The lower switch elements 73 turned on may be one or two. From time T35, the electric brake starts to take effect again, the braking current flows in the stator coil 345, and the speed of reducing the motor speed increases.

[0268] (Fifth Operation Example) Fig.57 is a timing chart of the fifth operation example of the working machine 4, and includes Fig.52 (C) is a timing chart of the actions corresponding to the control of S109 and S171. Fig.57 In FIG. 1 , S1 represents an overload detection threshold, and S2 represents a light load detection threshold.

[0269] Before time T41, the load is light, and the operation unit 50 drives the motor 340 in the high rotation mode (delta connection). That is, the operation unit 50 performs commutation control (drive control of the motor 340) based on the inverter circuit 64 in a state where the three delta connection relay elements 32 are turned on and the three star connection relay elements 33 are turned off.

[0270] At time T41, the trigger switch 306 is turned off, and the calculation unit 50 turns on all the lower switch elements 73 of the inverter circuit 64. The lower switch elements 73 that are turned on may be one or two. From time T41, the electric brake starts to take effect, the braking current flows in the stator coil 345, and the speed of reducing the motor speed increases.

[0271] This embodiment has the following effects.

[0272] (1) The calculation unit 50 is configured to perform control in the following order when the light load state turns into the overload state, namely, · turning off the six switch elements of the inverter circuit 64, · turning off the three delta connection relay elements 32, · turning on the three star connection relay elements 33, · controlling the inverter circuit 64 and driving the motor 340. This is advantageous in terms of durability of the three star connection relay elements 33 because no current flows at the moment when the three star connection relay elements 33 are turned on.

[0273] (2) The calculation unit 50 is configured to perform control in the following order when the overload state changes to the light load state, namely, · turning off the six switch elements of the inverter circuit 64, · turning off the three star connection relay elements 33, · turning on the three delta connection relay elements 32, · controlling the inverter circuit 64 and driving the motor 340. This is advantageous in terms of durability of the three delta connection relay elements 32 because no current flows at the moment when the three delta connection relay elements 32 are turned on.

[0274] (3) Fig.51 In the first control example shown, the operation unit 50 is configured to switch to the high torque mode (star connection) when the trigger switch 306 is turned off in the high rotation mode (delta connection), apply electric braking to the motor 340, and stop the motor 340. Therefore, compared with the case where the electric braking is applied in the high rotation mode (delta connection), the braking current can be suppressed and the temperature rise of the inverter circuit 64 can be suppressed. In addition, the reaction caused by the electric braking is suppressed, which is convenient to use.

[0275] (4) Fig.51In the first control example shown, the operation unit 50 is configured to perform control in the following order when the trigger switch 306 is turned off in the high rotation mode (delta connection), that is, · the six switch elements of the inverter circuit 64 are turned off, · the three delta connection relay elements 32 are turned off, · the three lower switch elements 73 of the inverter circuit 64 are turned on, and · the three star connection relay elements 33 are turned on. As a result, at the time when the three star connection relay elements 33 are turned on, the lower switch element 73 of the inverter circuit 64 is already turned on, and a closed loop for the flow of regenerative current is established. Therefore, even if the trigger switch 306 is turned off in a state where the motor speed is close to the no-load speed, the voltage applied to the switch element of the inverter circuit 64 can be suppressed from rising sharply, thereby suppressing the damage of electronic parts such as the switch element.

[0276] (5) Fig.52 In the second control example shown in (A), the operation unit 50 is configured to perform control in the following order when the trigger switch 306 is turned off in the high rotation mode (delta connection), that is, · the six switch elements of the inverter circuit 64 are turned off, · the three delta connection relay elements 32 are turned off, · the three star connection relay elements 33 are turned on, and · the three lower side switch elements 73 of the inverter circuit 64 are turned on. As a result, at the time point when the three star connection relay elements 33 are turned on, all the six switch elements of the inverter circuit 64 are turned off, and the closed loop for the regenerative current to flow is not established. In the first control example, a large regenerative current flows at the moment when the three star connection relay elements 33 are turned on and the closed loop is established, and there is a risk of damage to the three star connection relay elements 33, but the second control example can suppress such a risk of damage to the star connection relay elements 33.

[0277] (6) Fig.52In the third control example shown in (B), the operation unit 50 is configured to apply electric braking to the motor 340 to reduce the motor speed to below the specified speed when the trigger switch 306 is turned off in the high rotation mode (delta connection), and then switch to the high torque mode (star connection) to apply electric braking to the motor 340. During electric braking after the motor speed is reduced to below the specified speed, the three lower switch elements 73 of the inverter circuit 64 are turned on after the three star connection relay elements 33 are turned on, so that no current flows at the moment when the three star connection relay elements 33 are turned on, which is advantageous in terms of the durability of the three star connection relay elements 33. In addition, since the speed of the motor 340 is reduced to below the specified speed, the reverse voltage generated from the motor 340 when the three lower switch elements 73 of the inverter circuit 64 are turned on after the three star connection relay elements 33 are turned on can be suppressed. By suppressing the reverse voltage, the risk of damage to the switch element 73 can be reduced. In particular, by setting the predetermined number of revolutions so that the reverse voltage does not exceed the voltage of the battery pack 307, the risk of damage to the switch element 73 can be effectively reduced. In addition, since no current flows through the three star-connected relay elements 33 at the moment when the three star-connected relay elements 33 are turned on, this is advantageous in terms of the durability of the three star-connected relay elements 33.

[0278] (7) Fig.52 In the fourth control example shown in (C), when the trigger switch 306 is turned off in the high rotation mode (delta connection), the operation unit 50 turns on the three lower switch elements 73 of the inverter circuit 64, applies electric braking to the motor 340 while maintaining the high rotation mode (delta connection), and stops the motor 340. Therefore, even if the trigger switch 306 is turned off in the high rotation mode (delta connection), the on / off of the three delta connection relay elements 32 and the three star connection relay elements 33 is not switched, which is advantageous in terms of the durability of the three delta connection relay elements 32 and the three star connection relay elements 33.

[0279] (Implementation 7) Figures 58 to 62 This is related to the working machine 5 of the seventh embodiment of the present invention. The mechanical structure of the working machine 5 is partially different from that of the working machines of the above-mentioned embodiments. The circuit structure or control of the working machine 5 can be applied to any of the working machines of the above-mentioned embodiments. Fig.60 and Fig.61 , defines mutually orthogonal front and rear, up and down, left and right directions in the working machine 5. The working machine 5 is a portable circular saw. The working machine 5 includes a housing 1320.

[0280] The housing 1320 is, for example, a resin molded body, and includes a motor housing 1321 that accommodates the motor 340 and the like, a handle housing 1322 that is gripped by an operator, and a battery mounting portion 1323 .

[0281] The motor housing 1321 is a cylindrical portion whose central axis is substantially parallel to the left-right direction. The handle housing 1322 extends obliquely in the front-back and up-down directions above the right portion of the motor housing 1321. A trigger switch 1306 is provided at the upper end of the handle housing 1322 for the user to instruct the start and stop of the motor 340.

[0282] A metal gear box (saw cover) 1325 is connected to the left side of the handle housing 1322. The gear box 1325 accommodates a speed reduction mechanism (not shown) and covers the upper half of the saw teeth 1309.

[0283] The battery installation part 1323 is connected to the left side from the rear end of the handle housing 1322, and the battery pack 307 serving as a power source can be installed in a detachable manner. The working machine 5 is operated by the power of the battery pack 1307. The working machine 5 has an operation panel 1316 above the battery installation part 1323. The user switches the operation mode of the working machine 5 through the operation panel 1316.

[0284] A hook 1324 is installed in front of the handle housing 1322, and is configured to hook the working machine 5 on the hooked portion. The hook 1324 is rotatably installed on the housing 1320. In addition, a sub-handle 1326 is provided above the motor housing 1321. The sub-handle 1326 is a part that the operator holds during operation.

[0285] The working machine 5 includes a motor 340 inside a motor housing 1321 . The rotation of the motor 340 is decelerated by a deceleration mechanism in a gear box 1325 and is transmitted to the saw teeth 1309 .

[0286] The working machine 5 has a control board 1311 ( Fig.59 ), and a plurality of battery connection terminals (not shown) are provided inside the battery mounting portion 1323. The control substrate 1311 carries the arithmetic unit 50, or the control power supply circuit 51, the inverter circuit 64 and other circuits. The plurality of battery connection terminals face the bottom of the battery mounting portion 1323. The plurality of battery connection terminals contact and are electrically connected to the terminals of the battery pack 1307 mounted on the battery mounting portion 1323.

[0287] like Fig.59 As shown, the working machine 5 has a relay board 30 inside a motor housing 1321. The relay board 30 carries a plurality of relay elements 31. The relay board 30 is mounted on the motor 340 by screws or the like. The relay board 30 faces an air hole provided in the motor housing 1321.

[0288] Although the present invention has been described above by taking the embodiment as an example, the present invention is not limited to the embodiment. Various modifications can be made to the matters specifically described in the embodiment within the scope described in the claims.

[0289] In Embodiment 1 and Embodiments 4 to 6, the operation mode may be only the automatic switching mode. In such a case, the operation mode switching switch 312 and the operation mode display LED 313 may be omitted.

[0290] The motor current or motor speed, motor torque, battery current, sawtooth speed, sawtooth torque, time, various voltages (inverter voltage, rated voltage, allowable voltage, etc.), rated capacity, current ranges and time thresholds in each winding switching condition and overcurrent protection working condition, which are exemplified as specific numerical values ​​in the implementation manner, do not limit the scope of the invention in any way and can be changed arbitrarily according to the required specifications.

[0291] The working machine of the present invention is not limited to a portable circular saw, but may be other types of cutting working machines such as a table circular saw, a rotary band saw, a wire saw, a knife saw (reciprocating saw), and a brush cutter. In addition, the working machine of the present invention can also be a grinding working machine with a front end tool for grinding such as a grinder, a grinding working machine with a front end tool for grinding such as a grinder and a polisher, a cutting working machine with a front end tool for cutting such as a planer, a trimmer, and a router, a hole drilling working machine with a front end tool for drilling a hole such as a drill, a hammer, and a ground drill, an impact screwdriver, an impact wrench, a screwdriver drill bit, a shear wrench, a riveting machine, a fastening working machine with a front end tool for fastening such as a steel bar tying machine, a crimping working machine with a front end tool for crimping such as a crimping machine, a bending working machine with a front end tool for bending such as a steel bar bending machine, and a driving working machine with a front end tool for driving such as a nailing machine and a tacker.

[0292] Explanation of symbols

[0293] 1-5: Operating machine

[0294] 50: Operation unit (control unit)

[0295] 51: Control power supply circuit (control circuit voltage supply circuit)

[0296] 52: Current detection circuit (motor current detection circuit)

[0297] 53: Switch operation detection circuit

[0298] 54: Battery type detection circuit

[0299] 55: Voltage detection circuit (battery voltage detection circuit)

[0300] 56: Control signal circuit (control signal output circuit)

[0301] 57: Rotational position detection circuit (rotor position detection circuit)

[0302] 58: Speed ​​detection circuit

[0303] 59: Operation mode detection circuit

[0304] 61: Lighting LED drive circuit

[0305] 62: Lighting LED

[0306] 63: Hall IC (magnetic sensor)

[0307] 64: Inverter circuit

[0308] 65: Detection resistor

[0309] 66: LD detection circuit

[0310] 67: Battery Cell

[0311] 68: Protection IC (battery test control unit)

[0312] 69: Battery temperature detection circuit

[0313] 70: Thermistor (temperature detection element)

[0314] 71: Circuit temperature detection circuit

[0315] 72: Upper switch element

[0316] 73: Lower switch element

[0317] 74: Control circuit voltage detection circuit

[0318] 75: Display LED drive circuit

[0319] 76: Winding switching operation output circuit

[0320] 306: Trigger switch

[0321] 307: Battery Pack

[0322] 309: Sawtooth

[0323] 311: Control board

[0324] 312: Operation mode switch

[0325] 313: Operation mode display LED

[0326] 314: Light mode switch

[0327] 315: Light mode display LED

[0328] 316: Operation Panel

[0329] 317: Light mode display LED

[0330] 320: Shell

[0331] 321: Motor housing

[0332] 322: Handle housing

[0333] 323: Battery Installation Department

[0334] 324: Intermediate housing

[0335] 325: Gear box (saw cover)

[0336] 327: Battery connection terminal

[0337] 328: Cover member

[0338] 340: Motor

[0339] 341: Motor shaft

[0340] 342: Rotor core

[0341] 343: Rotor magnet (permanent magnet)

[0342] 344: stator core

[0343] 345: Stator coil

[0344] 346: Yoke

[0345] 347: Tooth (tooth part)

[0346] 1306: Trigger switch

[0347] 1307: Battery Pack

[0348] 1309: Sawtooth

[0349] 1311: Control board

[0350] 1316: Operation Panel

[0351] 1320: Shell

[0352] 1321: Motor housing

[0353] 1322: Handle housing

[0354] 1323: Battery Installation Department

[0355] 1324: Hook

[0356] 1325: Gear box (saw cover)

[0357] 1326: Deputy handle

Claims

1. A working machine, comprising: A motor, comprising a plurality of windings; A driving unit, for driving the motor; A connection switching unit configured to switch between a high-speed connection state in which the plurality of windings are connected to each other in a manner that provides a high-speed characteristic and a high-torque connection state in which the plurality of windings are connected to each other in a manner that provides a high-torque characteristic; an operating unit for operating the start and stop of the motor; and A control unit controls the driving unit and the wiring switching unit, The working machine is characterized in that The control unit is configured to be capable of executing connection switching control for switching from the high-speed connection state to the high-torque connection state, and to start the connection switching control when the rotation speed of the motor is greater than the no-load rotation speed of the high-torque connection state.

2. The working machine according to claim 1, characterized in that: The no-load speed in the high-torque connection state is the speed of the motor at the intersection of an extended line of the characteristic line of the high-torque connection state and a straight line with a torque of 0, when the relationship between the speed and torque of the motor is represented in the form of a characteristic line in a graph with torque on the horizontal axis and speed on the vertical axis.

3. The working machine according to claim 1, characterized in that: The control unit is configured to complete the connection switching control in a state where the rotation speed of the motor is equal to or less than the no-load rotation speed in the high-torque connection state.

4. The working machine according to claim 1, characterized in that: The control unit is configured to switch the drive unit to a drive stop state in which supply of drive power to the motor is stopped, and to switch the connection switch unit to a connection disconnection state in which at least a part of the plurality of windings is disconnected, during the connection switching control.

5. The working machine according to claim 4, characterized in that: The control unit is configured to switch the connection switching unit from the high-speed connection state to the connection disconnection state when the drive unit is in the drive stop state during the connection switching control.

6. The working machine according to claim 4, characterized in that: The control unit is configured to switch the connection switching unit from the connection disconnection state to the high torque connection state when the drive unit is in the drive stop state during the connection switching control.

7. A working machine comprising: A motor, comprising a plurality of windings; A driving unit, for driving the motor; A connection switching unit configured to be able to switch from one of a high-speed connection state in which the plurality of windings are connected to each other in a manner to achieve high-speed characteristics and a high-torque connection state in which the plurality of windings are connected to each other in a manner to achieve high-torque characteristics to another connection state; an operating unit for operating the start and stop of the motor; and A control unit controls the driving unit and the wiring switching unit, The working machine is characterized in that The control unit is configured to execute a wiring switching control for switching from one of the wiring states to the other wiring state, and in the wiring switching control, the driving unit is switched to a drive stop state in which supply of driving power to the motor is stopped, and the wiring switching unit is switched from one of the wiring states to a wiring disconnection state in which the plurality of windings are disconnected from each other.

8. The working machine according to claim 7, characterized in that: The control unit is configured to switch the connection switching unit from the one connection state to the connection disconnection state when the drive unit is in the drive stop state during the connection switching control.

9. The working machine according to claim 7, characterized in that: The control unit is configured to switch the connection switching unit from the connection disconnection state to the other connection state when the drive unit is in the drive stop state during the connection switching control.

10. A working machine, comprising: A motor having a rotor and a stator including a plurality of windings; a connection switching unit capable of switching the connection mode of the plurality of windings between a first connection mode for high rotation and a second connection mode for high torque; a driving unit having a plurality of switching elements for driving the motor; and A control unit controls the driving unit and the wiring switching unit, The working machine is characterized in that In the first mode, the control unit is configured to execute wiring switching control for switching the wiring mode from the first wiring mode to the second wiring mode according to an increase in the operating load applied to the motor, and is configured to not execute overload protection control for stopping the motor when the operating load satisfies an overload protection condition before the wiring switching control, but to execute the overload protection control only after the wiring switching control.

11. The working machine according to claim 10, characterized in that: In the first mode, the control unit is configured as follows: When the working machine is pressed against the object material with a first pressing force to perform working, or when the working machine is performed at a first working load increase rate, the connection switching control is executed, and When the working machine is pressed against a workpiece with a second pressing force greater than the first pressing force or is working with a second working load increase rate greater than the first working load increase rate, the overload protection control is executed immediately after the connection switching control to stop the motor.

12. A working machine comprising: A motor having a rotor and a stator including a plurality of windings; a connection switching unit capable of switching the connection mode of the plurality of windings between a first connection mode for high rotation and a second connection mode for high torque; A driving unit having a plurality of switching elements for driving the motor; a control unit, which controls the driving unit and the wiring switching unit; and The mode selection unit can be operated by the operator. The working machine is characterized in that The control unit is configured to be able to select which mode, the first mode or the second mode, to drive the motor in, according to an operator's operation of the mode selection unit. The first mode is configured to execute a connection switching control for switching the connection mode from the first connection mode to the second connection mode in response to an increase in a workload applied to the motor. The second mode is configured to maintain the connection configuration as the second connection configuration.

13. The working machine according to claim 12, characterized in that: In the first mode, the control unit is configured as follows: When the working machine is pressed against the workpiece with a first pressing force to perform the work, or when the work is performed at a first work load increase rate, the driving of the motor is maintained after the connection switching control is performed, and When the working machine is pressed against a workpiece with a second pressing force greater than the first pressing force or is working with a second working load increase rate greater than the first working load increase rate, overload protection control is executed immediately after the connection switching control is executed to stop the motor.

14. The working machine according to claim 13, characterized in that: In the second mode, the control unit is configured not to stop the motor by the overload protection control when the working machine is pressed against the workpiece with the second pressing force or the working machine is operated at the second working load increase rate.

15. The working machine according to claim 12, characterized in that: The control unit is configured to stop driving the motor when the connection switching control is executed, and to resume driving the motor immediately after the winding switching control is executed.

16. The working machine according to claim 15, characterized in that: In the first mode, the control unit is configured to stop the motor through the overload protection control immediately after executing the winding switching control and resuming the driving of the motor when the working machine is pressed against the object material with a second pressing force greater than the first pressing force or when the working machine is operated with a second working load increase rate greater than the first working load increase rate.

17. The working machine according to any one of claims 10 to 16, characterized in that: A first winding switching threshold value, which is a threshold value of the workload when the connection method is switched from the first connection method to the second connection method, is equal to or less than an overload protection threshold value, which is a threshold value of the workload when the motor is stopped by overload protection control.

18. The working machine according to claim 17, characterized in that: The first winding switching threshold is greater than 2 / 3 of the overload protection threshold.

19. The working machine according to claim 17, characterized in that: The first winding switching threshold is equal to the overload protection threshold.

20. The working machine according to any one of claims 10 to 16, characterized in that: The control unit is provided with a rest period in which all of the plurality of switch elements are turned off when the connection method is switched.

21. The working machine according to any one of claims 10 to 16, characterized in that: In the first mode, the control unit When the operation load increases and becomes equal to or greater than a first winding switching threshold value when the connection method is set to the first connection method, the connection method is switched to the second connection method, When the operation load decreases and becomes less than a second winding switching threshold value when the connection method is set to the second connection method, the connection method is switched to the first connection method, The first winding switching threshold is greater than the second winding switching threshold.

22. The working machine according to any one of claims 10 to 16, characterized in that: A battery installation unit is provided, wherein the battery installation unit can install a battery pack that serves as a power source for the motor and outputs a discharge stop signal when the discharge current exceeds a battery-side overcurrent protection threshold. When the current flowing in the motor exceeds the main body side overcurrent protection threshold, the control unit stops the motor. The battery side overcurrent protection threshold is greater than the main body side overcurrent protection threshold.

23. The working machine according to claim 22, characterized in that: The control unit is configured to stop the motor when the discharge stop signal is input.

24. A working machine, comprising: a motor having a plurality of windings driven by power supplied from a power source; a connection switching unit capable of switching a connection method of a plurality of windings of the motor between a first connection method for high rotation and a second connection method for high torque; A control unit controls the motor and the wiring switch unit; a housing for accommodating the motor, the wiring switch and the control unit; and a detection unit for detecting a physical quantity that changes due to driving of the motor or a type of the power supply, The working machine is characterized in that The control unit is configured to execute connection switching control for switching the connection method from the first connection method to the second connection method when a predetermined winding switching condition is satisfied. The detected value includes a workload applied to the motor, The winding switching condition includes that a duration of any of the workloads being equal to or greater than a load threshold value is equal to or greater than a time threshold value that differs depending on the magnitude of the workload.

25. The working machine according to claim 24, characterized in that: The control unit is configured as follows: When a first workload is applied to the motor for a first period of time, the connection method is switched from the first connection method to the second connection method. When a second workload greater than the first workload continues to be applied to the motor for a second time shorter than the first time, the connection method is switched from the first connection method to the second connection method.

26. The working machine according to claim 24, characterized in that: The detected values ​​include a work load applied to the motor and a temperature of a heating element constituting the working machine. The winding switching condition includes that a duration of any of the workloads that is equal to or greater than a load threshold value is equal to or greater than a time threshold value, and a combination of the workload and the time threshold value differs depending on the temperature.

27. The working machine according to claim 26, characterized in that: The control unit is configured as follows: When the temperature of the heating element is at a first temperature and the workload applied to the motor is at a predetermined value for a first time, the wiring method is switched from the first wiring method to the second wiring method, When the temperature of the heating element is a second temperature higher than the first temperature and the workload is the predetermined value for a second time shorter than the first time, the connection method is switched from the first connection method to the second connection method.

28. The working machine according to claim 24, characterized in that: The detected values ​​include the workload applied to the motor and the type of the power source, The winding switching condition includes that a duration of any of the operational loads that is equal to or greater than a load threshold value is equal to or greater than a time threshold value, and a combination of the operational load and the time threshold value varies depending on the rated capacity.

29. The working machine according to claim 28, characterized in that: The control unit is configured as follows: When the capacity of the power source is a first capacity and the workload applied to the motor is a first load value for a predetermined time, the connection method is switched from the first connection method to the second connection method, When the capacity of the power source is a second capacity smaller than the first capacity and the workload is a second load value smaller than the first load value for the predetermined time, the connection method is switched from the first connection method to the second connection method.

30. The working machine according to claim 24, characterized in that: The winding switching condition is set based on a detection value in the detection unit so as to switch the connection method from the first connection method to the second connection method before the motor stops due to an overload protection being activated.

31. The working machine according to claim 30, characterized in that: The overload protection is configured to be executed when a first workload, which is a workload applied to the motor, continues for a first time. The switching of the connection method is configured to be performed when a second workload, which is the workload, continues for a second time.

32. The working machine according to claim 31, characterized in that: The first workload and the second workload are substantially the same load value or load range, The second time is shorter than the first time.

33. The working machine according to claim 31, characterized in that: The first time and the second time are approximately the same time or time range, The second workload is less than the first workload.

34. The working machine according to any one of claims 31 to 33, characterized in that: When the second workload is large, the second time is shorter than when the second workload is small.

35. The working machine according to claim 34, characterized in that: When the first workload is large, the first time is shorter than when the first workload is small.

36. The working machine according to claim 24, characterized in that: The power source includes a battery pack that is attachable to and detachable from the housing.

37. A working machine comprising: A motor having a rotor and a stator including a plurality of windings; A connection switching unit for switching the connections of the plurality of windings; A driving unit having a plurality of switching elements for driving the motor; a control unit, which controls the driving unit and the wiring switching unit; and A switch for instructing the start and stop of the motor, The working machine is characterized in that The control unit is configured to control the connection switching unit so that when a load applied to the motor increases, the connection is switched to change from a high rotation mode to a high torque mode. The control unit is configured to switch to the high torque mode and apply electric braking to the motor when the switch is turned off in the high rotation mode.

38. The working machine according to claim 37, characterized in that: The connection switching unit includes a high rotation side switching unit that is turned on in the high rotation mode, and a high torque side switching unit that is turned on in the high torque mode. The control unit is configured such that the switch is disconnected in the high rotation mode and switched to the high torque mode, and when electric braking is applied to the motor, the plurality of switching elements and the high rotation side switching unit are disconnected, and a part of the plurality of switching elements and the high torque side switching unit are connected.

39. The working machine according to claim 38, characterized in that: The control unit is configured such that the switch is disconnected in the high rotation mode and switched to the high torque mode, and when electric braking is applied to the motor, the multiple switching elements and the high rotation side switching unit are disconnected, the high torque side switching unit is connected, and then a part of the multiple switching elements are connected.

40. The working machine according to claim 38, characterized in that: The control unit is configured such that the switch is disconnected in the high rotation mode and switched to the high torque mode, and when electric braking is applied to the motor, the multiple switching elements and the high rotation side switching unit are disconnected, and then a part of the multiple switching elements are connected, and then the high torque side switching unit is connected.

41. The working machine according to claim 37, characterized in that: The control unit is configured to apply electric braking to the motor to reduce the number of revolutions of the motor to a predetermined number or less when the switch is turned off in the high rotation mode, and then switch to the high torque mode to apply electric braking to the motor.

42. A working machine, comprising: A motor having a rotor and a stator including a plurality of windings; A connection switching unit for switching the connections of the plurality of windings; A driving unit having a plurality of switching elements for driving the motor; a control unit, which controls the driving unit and the wiring switching unit; and A switch for instructing the start and stop of the motor, The working machine is characterized in that The control unit is configured to control the connection switching unit so that when a load applied to the motor increases, the connection is switched to change from a high rotation mode to a high torque mode. The control unit is configured to apply an electric brake to the motor in the high rotation mode to stop the motor when the switch is turned off in the high rotation mode.

43. The working machine according to claim 37 or 42, characterized in that: The connection in the high rotation mode is a delta connection, and the connection in the high torque mode is a Y connection.

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