Work equipment

Abstract

This allows for comfortable and continuous machining operations while suppressing cost increases and performance degradation in terms of control. [Solution] The work machine comprises a motor 110, an output shaft 43 for holding a cutting tool, a drive circuit unit 200 for supplying current to the motor, and a controller unit 300 for controlling the current flowing to the motor. The controller unit controls the current flowing to the motor by a first control mode M1 controlled by a first switching frequency F1, and a second control mode M2 ​​that suppresses the current flowing to the motor more than in the first control mode M1 by a second switching frequency F2, and also performs feedback control so that the current flowing to the motor does not exceed a predetermined value, the motor current MImax. As a result, even when the load is large when the motor starts up, the current flowing to the motor can be suppressed without putting a load on the switching elements.

Description

Technical Field

[0004] , , , , , ,

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

Background Art

[0002] The working machine (circular saw) described in Patent Document 1 below includes a motor, a plunger that moves in a machining direction and a return direction opposite to the machining direction by the motor, and performs machining on a workpiece by a saw blade when moving in the machining direction. Further, the working machine has a control unit that controls the motor at a first advance angle when the plunger moves in the return direction, and controls the motor at a second advance angle smaller than the first advance angle at least in a section where the load on the plunger is large when the plunger moves in the machining direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in the above working machine, for example, when performing a butt cut in which the working machine is operated from a state where the saw teeth are applied to the cutting target material before driving the motor. At this time, a large current may be generated in the working machine due to the inrush current generated when the motor starts and the increase in the driving current due to the load, and the motor may stop due to the overcurrent protection function provided in the working machine. As means for solving the above problems, for example, it is conceivable to increase the ratings of the battery or drive electrical components so as to match the generated large current, or to relax the overcurrent protection function. However, increasing the rating of batteries or drive electrical components may lead to larger components or increased costs. Furthermore, relaxing overcurrent protection may prevent prompt protection in the event of an overcurrent. On the other hand, for work machines, it is desirable to design the system in a way that minimizes cost increases and performance degradation in terms of control.

[0005] Taking the above facts into consideration, the present invention aims to provide a machine that allows for comfortable continuous processing work while suppressing cost increases and performance degradation in terms of control. [Means for solving the problem]

[0006] One or more embodiments of the present invention are work machines comprising: a motor; an output shaft connected to the motor and holding a cutting tool; a switching element that rotates the motor by supplying a current to the motor; and a controller unit that detects the current flowing through the motor and controls the current flowing through the motor via the switching element, wherein the controller unit is configured to perform a first control mode in which the current flowing through the motor is controlled by a first switching frequency; and a second control mode in which the current flowing through the motor is controlled by a second switching frequency having a higher frequency than the first switching frequency, and feedback control is performed so that the current flowing through the motor does not exceed a predetermined value.

[0007] One or more embodiments of the present invention are work machines in which the controller unit performs the feedback control by controlling the duty cycle of the second switching frequency in the second control mode.

[0008] One or more embodiments of the present invention are work machines in which the controller unit switches from the first switching frequency to the second switching frequency when the current flowing to the motor after the motor has been started becomes equal to or greater than a first threshold.

[0009] One or more embodiments of the present invention are work machines in which the controller unit executes the second control mode when the current flowing to the motor becomes equal to or greater than a second threshold.

[0010] One or more embodiments of the present invention are work machines in which, after starting the motor from a stopped state, the controller unit starts the motor in the first control mode, and thereafter, when the current exceeds a first threshold, controls the motor in the second control mode until a first predetermined time has elapsed.

[0011] One or more embodiments of the present invention are work machines in which the controller unit switches to control by the first control mode after control by the second control mode continues for a second predetermined time or longer.

[0012] One or more embodiments of the present invention are work machines having a transmission mechanism that converts the power of the motor into reciprocating motion and transmits it to the output shaft, wherein the tip tool is a blade with a cutting edge, and when the motor is started with the blade pressed against the workpiece and a cutting operation is performed on the workpiece, the machine is controlled by the second control mode, and when the motor is started without load to prevent cutting by the blade, the machine does not perform control by the second control mode at least until a third predetermined time has elapsed after the motor is started. [Effects of the Invention]

[0013] According to one or more embodiments of the present invention, it is possible to perform processing work without any discomfort while suppressing cost increases. [Brief explanation of the drawing]

[0014] [Figure 1] This is a side view of the electric cutting machine according to this embodiment, seen from the right side. [Figure 2] Figure 1 is a side view showing the interior of the electric cutting machine as seen from the right side. [Figure 3]It is a block diagram showing the electrical configuration of an electric cutter according to the first embodiment of the present invention. [Figure 4] It is a block diagram showing the electrical configuration of a controller unit according to the first embodiment of the present invention. [Figure 5] It is a waveform diagram showing control signals output by a controller unit according to the first embodiment of the present invention, where a) shows a first switching frequency signal, b) shows a second switching frequency signal, and c) shows a duty ratio control signal at the second switching frequency. [Figure 6] It is a graph showing the time transition of the current flowing through a motor according to the first embodiment of the present invention. [Figure 7] It is a flowchart showing the processing of a controller unit according to the first embodiment of the present invention. [Figure 8] It is a block diagram showing the electrical configuration of a controller unit according to the second embodiment of the present invention. [Figure 9] It is a schematic view seen from the right showing the cutting state of an electric cutter according to the second embodiment of the present invention, where a) shows the abutting state and b) shows the no-load state. [Figure 10] It is a graph showing the time transition of the current flowing through a motor according to the second embodiment of the present invention, where a) shows the current flowing through the motor in the abutting state and b) shows the current flowing through the motor in the no-load state. [Figure 11] It is a flowchart showing the processing of a controller unit according to the second embodiment of the present invention. [Figure 12] It is a graph showing the time transition of the current flowing through a motor showing a modification example of the present invention, where a) shows the case where the current flowing through the motor is smaller than the motor current MI1 and b) shows the case where the current flowing through the motor is smaller than the motor current MI2.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, the electric cutter (saber saw) 10 as a working machine according to the present embodiment will be described with reference to FIGS. 1 to 12. The arrows UP, FR, and RH appropriately shown in the drawings indicate the upper side, the front side, and the right side of the electric cutter 10, respectively. In the following description, when the up-down, front-back, and left-right directions are used for explanation, unless otherwise specified, they indicate the up-down direction, the front-back direction, and the left-right direction of the electric cutter 10.

[0016] <First Embodiment> The electric cutter 10 according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 7.

[0017] The electric cutter 10 is configured as an electric tool for performing cutting processing on a workpiece such as a pipe. As shown in FIGS. 1 and 2, the electric cutter 10 includes a housing 20 that constitutes the outer shell of the electric cutter 10, an inner case 30 housed and fixed inside the housing 20, and a mounting portion 40 that holds the tip tool TT. Inside the housing 20 and the inner case 30, a trigger switch portion 50, a drive mechanism portion 60, a battery portion 70, a motor portion 100, a drive circuit portion 200, and a controller portion 300 are included. Hereinafter, each component of the electric cutter 10 will be described.

[0018] (Regarding the housing 20) The housing 20 is formed in a substantially hollow cylindrical shape extending in the front-back direction as a whole. The housing 20 includes a front housing portion 20A that constitutes the front portion of the housing 20 and a handle housing portion 20B as a handle that constitutes the rear end portion of the housing 20. The front housing portion 20A extends in the front-back direction, and the rear end portion of the front housing portion 20A is bent downward. The handle housing portion 20B extends in the up-down direction, and both the upper and lower end portions of the handle housing portion 20B are bent forward and connected to the rear end portion of the front housing portion 20A. During cutting processing, the operator grips the handle housing portion 20B to perform the cutting processing. A mounting section 40 is provided on the front inner side of the front housing section 20A. A trigger switch section 50 is provided on the rear of the handle housing section 20B. A battery section 70 is detachably attached to the lower end of the handle housing section 20B. Furthermore, the controller unit 300 is fixed inside the rear lower part of the front housing unit 20A.

[0019] (Regarding Inner Case 30) As shown in Figure 2, the inner case 30 is formed in a roughly rectangular box shape that extends in the front-to-back direction. The inner case 30 is housed in the upper part of the front housing portion 20A and is fixed to the housing 20 by being sandwiched from the outside in the left-right direction by the housing members that make up the housing 20. Inside the inner case 30 are the motor unit 100 and the drive mechanism unit 60. A motor holder portion 31 for holding the motor unit 100, which will be described later, is formed at the rear end of the inner case 30. The motor holder portion 31 is formed in a roughly rectangular cylindrical shape that protrudes downward from the inner case 30. A communication portion 32 for housing a part of the drive shaft 120 of the motor unit 100 is formed on the upper side of the motor holder portion 31.

[0020] (Regarding the mounting part 40) The mounting section 40 is located on the front side of the housing 20 and includes a dust sleeve 41, a fixing plate 42, and an output shaft 43 with a blade mounting section BA at its front end.

[0021] The dust sleeve 41 is provided at the front end of the output shaft 43. The dust sleeve 41 is formed in a substantially bottomed cylindrical shape that is open to the front. The front end of the output shaft 43 is inserted through the bottom of the dust sleeve 41, and the blade mounting portion BA is positioned inside the dust sleeve 41 of the housing 20. The front end of the dust sleeve 41 is assembled to the housing 20, and the dust sleeve 41 is positioned inside the front end of the housing 20.

[0022] The fixing plate 42 is formed in a roughly U-shaped plate form that is open upward when viewed from the front, and is fixed to the housing 20. The lower end portion of the base portion BS is connected to the front end of the fixing plate 42 so as to be rotatable in the left-right direction as the axial direction.

[0023] The output shaft 43 is connected to the motor 111 via a drive mechanism 60, which will be described later, and holds the blade BL as the tip tool TT. The output shaft 43 is formed in a substantially bottomed cylindrical shape that is open to the front. The rear end of the output shaft 43 is engaged with a plunger 63 in the drive mechanism 60. The front end portion of the output shaft 43 is supported by rolling by a roller unit (not shown) provided at the front end of the inner case 30. A blade mounting portion BA is also provided at the front end of the output shaft 43. The blade mounting portion BA is formed in a substantially stepped cylindrical shape with the front-rear direction as its axial direction, and the rear end of the blade mounting portion BA is fixed to the output shaft 43 with it inserted into the front end of the output shaft 43.

[0024] The blade BL is mounted in the blade mounting section BA. The blade BL is, for example, a sawtooth, and is formed in a substantially elongated plate shape with the left-right direction being the plate thickness direction and extending in the front-rear direction. As a result, when the drive mechanism 60 is operated, the blade BL moves back and forth together with the output shaft 43.

[0025] (Regarding the trigger switch section 50) The trigger switch unit 50 is located on the upper end of the handle housing unit 20B. The trigger switch unit 50 includes a trigger 51 that protrudes forward from the handle housing unit 20B and is configured to be pullable backward, and a switch unit 52 located on the handle housing unit 20B behind the trigger 51. The switch unit 52 has a switch (not shown) that is operated by the trigger 51, and this switch is electrically connected to the controller unit 300. The trigger switch unit 50 transmits operation information from the trigger 51 to the controller unit 300.

[0026] (Regarding the drive mechanism 60) The drive mechanism 60 is housed inside the inner case 30. The drive mechanism 60 consists of a drive gear 61, a crankpin 62, and a plunger 63. The plunger 63 and the output shaft 43 in the drive mechanism 60 are slidably mated together.

[0027] The drive gear 61 is formed in a substantially disc shape with its thickness in the vertical direction. For example, a bevel gear is formed on the outer circumference of the drive gear 61. The drive gear 61 meshes with the gear 121 on the drive shaft 120 of the motor unit 100 at the communication portion 32 of the inner case 30. As a result, when the motor unit 100 is operating, the rotation of the gear 121 is transmitted to the drive gear 61. Furthermore, a crankpin 62 is provided on the drive gear 61 so as to be rotatable as a connecting part. The crankpin 62 is formed in a substantially cylindrical shape with its axial direction in the vertical direction, is positioned eccentrically with respect to the rotation axis of the drive gear 61, and protrudes upward from the drive gear 61.

[0028] The plunger 63 is formed in an elongated shape extending in the front-rear direction. A plunger connecting hole PH is formed through the plunger 63 in an elongated shape with the left-right direction as its longitudinal direction. A crank pin 62 provided on the drive gear 61 is inserted into the plunger connecting hole PH in the plunger 63 so as to be movable in the left-right direction and engageable in the front-rear direction. As a result, the rotational motion of the drive shaft 120 in the motor 110 is transmitted to the drive gear 61, the rotational force of the drive gear 61 is converted by the plunger 63, and the output shaft 43 moves back and forth in the front-rear direction. The drive mechanism 60 is provided as a mechanism that converts the rotational motion of the drive shaft 120 in the motor 110 into reciprocating motion in the forward and backward direction via the drive gear 61 and plunger 63. As a result, the rotational motion of the drive shaft 120 in the motor 110 causes the output shaft 43 to reciprocate in the forward and backward direction.

[0029] (Regarding the battery unit 70) The battery unit 70 is detachably attached to the lower end of the handle housing unit 20B. The battery unit 70 is electrically connected to the drive circuit unit 200, and power is supplied from the battery unit 70 to the motor unit 100 and the controller unit 300 via the drive circuit unit 200.

[0030] (Regarding the motor unit 100) The motor unit 100 is located on the lower rear side of the inner case 30. The motor unit 100 includes a motor 110, a drive shaft 120, and a rotation sensor 130. The drive shaft 120 of the motor 110 extends in the vertical direction, and a gear 121 is fixed to the upper end of the drive shaft 120. The upper end portion of the drive shaft 120 is housed in a communication section 32 within the inner case 30, and within the inner case 30, the gear 121 is engaged with a drive gear 61 provided in the drive mechanism section 60. As shown in Figure 3, the motor unit 100 is electrically connected to the drive circuit unit 200 and the controller unit 300, which will be described later.

[0031] The motor 110 is connected to the output shaft 43 via the gear 121 and the drive gear 61 and plunger 63 in the drive mechanism 60. For example, a brushless motor is used for the motor 110, and the anode and cathode of the motor 110 are electrically connected to the drive circuit 200.

[0032] The rotation sensor 130 is a magnetic sensor, such as one using a Hall element. The rotation sensor 130 detects the rotation information of the motor 110 and transmits the rotation information of the motor 110 to the controller unit 300. The rotation sensor 130 is located on the underside of the motor 110 and is electrically connected to the controller unit 300.

[0033] (Regarding the drive circuit section 200) The drive circuit unit 200 includes a switching element 210 and a motor current detection unit 220. The drive circuit unit 200 is electrically connected to the motor unit 100 and the controller unit 300. The drive circuit unit 200 is a power supply that supplies drive current to the motor 110, and the drive current is supplied to the motor 110 by the controller unit 300 controlling the switching element 210.

[0034] The switching element 210 is equipped with, for example, one or more power FETs (field-effect transistors) and supplies current to the motor 110 based on control signals supplied from the controller unit 300. A pulse wave, which is a control signal transmitted from the controller unit 300, is input to the gate terminal of the switching element 210 via a control circuit such as a filter circuit (not shown) in the drive circuit unit 200. For example, the battery unit 70 is electrically connected to the drain terminal of the switching element 210, and the current controlled by the controller unit 300 is supplied from the battery unit 70 to the motor 110 via the drain and source terminals of the switching element 210. A filter (not shown) is configured on the output side of the switching element 210 to smooth the output current value.

[0035] The motor current detection unit 220 detects the current value supplied from the switching element 210 to the motor 110. The motor current detection unit 220 transmits information regarding the detected current value to the controller unit 300. The information regarding the current value transmitted by the motor current detection unit 220 may be, for example, the voltage value generated across the shunt resistor, or numerical data information converted by an A / D converter.

[0036] Furthermore, the drive circuit 200 may be provided with an overcurrent protection circuit that limits the current value or stops the current when an excessive current flows through the switching element 210.

[0037] (Regarding the controller unit 300) The controller unit 300 detects the current flowing through the motor 110 and controls the current flowing through the motor 110 via the switching element 210. The controller unit 300 is configured to execute a first control mode M1 in which the current flowing through the motor 110 is controlled by a first switching frequency F1, and a second control mode M2 ​​in which the current flowing through the motor 110 is controlled by a second switching frequency F2 which has a higher frequency than the first switching frequency F1, and feedback control is performed so that the current flowing through the motor 110 does not exceed a predetermined motor current MImax. As shown in Figure 4, the controller unit 300 is electrically connected to the switch unit 52 in the trigger switch unit 50, the rotation sensor 130 in the motor unit 100, and the switching element 210 and motor current detection unit 220 in the drive circuit unit 200.

[0038] Specifically, the controller unit 300 includes a processor 310 and a memory 320. The processor 310 includes a determination unit 311, a control unit 312, and a time count unit 313. Each part of the processor 310 and the memory 320 input and output various types of information via the bus line BU.

[0039] The determination unit 311 determines whether the trigger 51 is being operated based on the operation information transmitted from the switch unit 52 in the trigger switch unit 50. The operation information transmitted from the switch unit 52 may be one of two types of information, ON / OFF, or it may be data information obtained by converting the trigger 51's pulling operation state into numerical information. The determination unit 311 stores the operation information transmitted from the switch unit 52 in the storage unit 321 of the memory 320. Furthermore, the determination unit 311 determines the state of the motor 110 based on the information transmitted from the rotation sensor 130 in the motor unit 100 and the information transmitted from the motor current detection unit 220 in the drive circuit unit 200. Specifically, the determination unit 311 determines whether or not the motor 110 is rotating based on the information transmitted from the rotation sensor 130. The determination unit 311 also obtains the current value supplied to the motor 110 based on the information transmitted from the motor current detection unit 220. The determination unit 311 stores the obtained information in the storage unit 321.

[0040] The control unit 312 switches between the first switching frequency F1 in the first control mode M1 and the second switching frequency F2 in the second control mode. As shown in Figure 5a, the control unit 312 supplies current to the motor 110 in the first control mode M1 by transmitting a pulse wave of the first switching frequency F1 to the switching element 210. Also, as shown in Figure 5b, the control unit 312 supplies current to the motor 110 in the second control mode M2 ​​by transmitting a pulse wave of the second switching frequency F2 to the switching element 210. Furthermore, as shown in Figure 5c, the control unit 312 performs feedback control in the second control mode M2 ​​by controlling the duty cycle of the second switching frequency F2.

[0041] As shown in Figure 6, the control unit 312 performs feedback control in the second control mode so that the current flowing through the motor 110 does not exceed a predetermined value, the motor current MImax. Here, by controlling the duty cycle of the second switching frequency F2, the control unit 312 controls the current flowing to the motor 110 without changing the frequency of the second switching frequency F2. For example, when it is necessary to increase the current flowing to the motor 110 when cutting the workpiece CM, the control unit 312 increases the current flowing to the motor 110 by increasing the time the pulse wave is in the Hi state and decreasing the time the pulse wave is in the Lo state (increasing the duty cycle). Furthermore, for example, the motor current MImax is set so that the current flowing through the motor 110 does not exceed the rating of the motor 110 or the switching element 210. When the current flowing through the motor 110 increases during the cutting of the workpiece CM and is likely to exceed the motor current MImax, the control unit 312 reduces the current flowing through the motor 110 by decreasing the time the pulse wave is in the Hi state and increasing the time the pulse wave is in the Lo state (decreasing the duty cycle).

[0042] As shown in Figure 6, the control unit 312 switches from the first switching frequency F1 to the second switching frequency F2 in the first control mode M1 when the current flowing through the motor 110 after the motor 110 has started up becomes greater than or equal to the motor current MI1, which is the first threshold. In other words, when the current flowing through the motor 110 becomes greater than or equal to the motor current MI1, the control unit 312 suppresses the current flowing through the motor 110 by switching from the first switching frequency F1 to the second switching frequency F2.

[0043] Furthermore, when the current flowing through the motor 110 exceeds the motor current MI2, which is the second threshold, the control unit 312 executes a second control mode in which it performs feedback control by controlling the duty cycle of the second switching frequency F2. Therefore, by maintaining the second switching frequency F2 and performing feedback control to control the duty cycle, the control unit 312 more reliably suppresses the increase in the current flowing through the motor 110.

[0044] Furthermore, after the control unit 312 starts the stopped motor 110, the control unit 312 starts the motor 110 in the first control mode M1, and then, when the motor current becomes MI1 or higher, it controls the motor 110 in the second control mode M2 ​​until a predetermined time PT1, which is the first predetermined time, has elapsed. The control unit 312 starts the motor 110 in the first control mode M1, and if the current flowing to the motor 110 does not reach the motor current MI2, it sets the execution time of the second control mode M2 ​​to a predetermined time PT1 to suppress the temperature rise of the switching element 210 and control the current flowing to the motor 110 so as not to exceed the component ratings of the motor 110 or the switching element 210.

[0045] Furthermore, the control unit 312 switches to control under the first control mode M1 after the control under the second control mode M2 ​​continues for a predetermined time PT2 or longer, which is a second predetermined time. In other words, the control unit 312 does not allow the second control mode M2 ​​to continue for a predetermined time PT2 or longer, thereby limiting the time during which the motor 110 or switching element 210 is overloaded and heats up. The control unit 312 prevents the component lifespan of the motor 110 or switching element 210 from being shortened.

[0046] Furthermore, if the control unit 312 determines that the motor 110 is not rotating even after the protective stop time TS has elapsed since starting the motor 110 from a stopped state, it stops the current flowing to the motor 110.

[0047] The time count unit 313 starts counting time based on control information from the control unit 312. The time count unit 313 also transmits time count information to the control unit 312 based on the control information from the control unit 312. Specifically, for example, when control information to start time counting is transmitted from the control unit 312, the time counting unit 313 starts time counting. When control information to acquire time count information is transmitted from the control unit 312, the time counting unit 313 transmits the time count information at that time to the control unit 312.

[0048] As described above, the controller unit 300 controls the current flowing to the switching element 210 based on the current value information required for cutting the workpiece CM, thereby controlling the current flowing to the motor 110 so that it does not exceed a predetermined value, the motor current MImax. In other words, it controls the current flowing to the motor 110 so that it does not exceed the rating of the switching element 210 or the rating of the motor 110. Furthermore, the controller unit 300 controls the current value required for cutting the workpiece CM to the motor 110 so that the overcurrent protection circuit does not activate.

[0049] Memory 320 is configured to include ROM (Read Only Memory), RAM (Random Access Memory), etc., which are not shown in the figure. Memory 320 stores, for example, a control program and various data input from the processor 310. In this embodiment, memory 320 pre-stores, for example, the first switching frequency in the first control mode M1 and the second switching frequency F2 in the second control mode M2, the motor currents MI1 to MI3 as first to third thresholds, the first to third predetermined times PT1 to PT3, the protection stop time TS, etc.

[0050] (Regarding the processing flow of the controller unit 300) In the cutting process of the electric cutting machine 10 configured as described above, the motor unit 100 operates when the operator pulls the trigger switch unit 50, which causes the controller unit 300 to control the drive circuit unit 200. As a result, the drive gear 61, which is meshed with the gear unit 112 of the drive shaft 120 of the motor 110, rotates. Consequently, the output shaft 82 of the drive mechanism unit 60, which is connected to the crankpin 62 of the drive gear 61, reciprocates in the front-rear direction together with the blade BL. Thus, cutting is performed on the material to be cut. The processing flow of the controller unit 300 will be explained below with reference to Figure 7.

[0051] The determination unit 311 in the processor 310 of the controller unit 300 determines whether the trigger 51 is being operated based on the operation information transmitted from the switch unit 52 in the trigger switch unit 50, and the determination unit 311 transmits the result to the control unit 312 via the storage unit 321 (step S110).

[0052] If the determination unit 311 determines that the trigger 51 has not been operated ("NO" in step S110), the control unit 312 proceeds to step S110.

[0053] On the other hand, if the determination unit 311 determines that the trigger 51 has been operated ("YES" in step S110), the control unit 312 sets the control mode to the first control mode M1 (step S120). Then, the control unit 312 causes the time count unit 313 to start counting time (step S130) and transitions the process to step S140.

[0054] The determination unit 311 determines whether or not the motor 110 is rotating based on the information transmitted from the rotation sensor 130 in the motor unit 100 (step S140).

[0055] If the determination unit 311 determines that the motor 110 is rotating (YES in step S140), the control unit 312 proceeds to step S170.

[0056] On the other hand, if the determination unit 311 determines that the motor 110 is not rotating ("NO" in step S140), the control unit 312 obtains time count information from the time count unit 313 (step S150). If the time count information is within the protection stop time TS ("YES" in step S150), the control unit 312 transitions the process to step S140. If the time count information is not within the protection stop time TS ("NO" in step S150), the control unit 312 transitions the process to step S160 and terminates the process by implementing control to stop the current flowing to the motor 110.

[0057] The determination unit 311 determines, based on the information from the motor current detection unit 220, whether the current supplied to the motor 110 is greater than or equal to the motor current MI1 (step S170).

[0058] If the determination unit 311 determines that the current supplied to the motor 110 is not equal to or greater than the motor current MI1 ("NO" in step S170), the control unit 312 proceeds to step S170.

[0059] On the other hand, if the determination unit 311 determines that the current supplied to the motor 110 is greater than or equal to the motor current MI1 ("YES" in step S170), the control unit 312 sets the second switching frequency F2 (step S180) and transitions the process to step S190.

[0060] The determination unit 311 determines, based on the information from the motor current detection unit 220, whether the current supplied to the motor 110 is equal to or greater than the motor current MI2 (step S190).

[0061] If the determination unit 311 determines that the current supplied to the motor 110 is equal to or greater than the motor current MI2 ("YES" in step S190), the control unit 312 switches the control mode to the second control mode M2 ​​(step S210) and proceeds to step S220.

[0062] On the other hand, if the determination unit 311 determines that the current supplied to the motor 110 is greater than or equal to the motor current MI2 ("NO" in step S190), the control unit 312 obtains time count information from the time count unit 313 (step S200). If the time count information is within the elapsed time T1 ("YES" in step S200), the control unit 312 transitions the process to step S190. If the time count information is not within the elapsed time T1 ("NO" in step S200), the control unit 312 transitions the process to step S230, sets the control mode to the first control mode M1, and terminates the process.

[0063] The control unit 312 obtains time count information from the time count unit 313, and if the time count information is within the elapsed time T2, it proceeds to step S220.

[0064] On the other hand, if the time count information is not within the elapsed time T2 ("NO" in step S220), the control unit 312 transitions the process to step S230, sets the control mode to the first control mode M1, and terminates the process.

[0065] (Effects and Benefits) As described above, the electric cutting machine 10 as a work machine according to this embodiment 1 comprises a motor 110, an output shaft 43 connected to the motor 110 and holding the cutting tool TT, a switching element 210 that rotates the motor 110 by supplying current to the motor 110, and a controller unit 300 that detects the current flowing through the motor 110 and controls the current flowing through the motor 110 via the switching element 210. The controller unit 300 is configured to execute a first control mode M1 that controls the current flowing through the motor 110 by a first switching frequency F1, and a second control mode M2 ​​that controls the current flowing through the motor 110 by a second switching frequency F2 with a frequency higher than the first switching frequency F1, and also performs feedback control so that the current flowing through the motor 110 does not exceed a predetermined value, the motor current MImax. In other words, the electric cutting machine 10 detects the current value flowing to the motor 110 via the controller unit 300. The controller unit 300 then controls the current flowing to the motor 110 by switching between a first control mode M1 and a second control mode M2 ​​based on the current value information flowing to the motor 110. Therefore, the electric cutting machine 10 can control the current flowing through the motor 110 so that it does not exceed a predetermined motor current MImax by switching between a first control mode M1 and a second control mode M2 ​​based on the current value information flowing through the motor 110 and controlling the current flowing through the switching element 210 based on the cutting load. In other words, by controlling the current flowing through the motor 110 so that it does not exceed the current value of the switching element 210 or the motor 110, components can be protected and the need to use components with high rated values ​​is reduced. Furthermore, since the operation is not interrupted by the activation of the overcurrent protection circuit, the electric cutting machine 10 can perform continuous cutting work without any discomfort. Therefore, it is possible to perform processing work comfortably while keeping cost increases to a minimum.

[0066] Furthermore, the controller unit 300 performs feedback control by controlling the duty cycle of the second switching frequency F2 in the second control mode M2. In other words, by controlling the duty cycle of the second switching frequency F2, the control unit 312 controls the current flowing to the motor 110 without changing the frequency of the second switching frequency F2. For example, the motor current MImax is set so that the current flowing to the motor 110 does not exceed the rating of the motor 110 or the switching element 210. When the current flowing to the motor 110 increases during the cutting of the workpiece CM and is likely to exceed the motor current MImax, the control unit 312 reduces the current flowing to the motor 110 by decreasing the time the pulse wave is in the Hi state and increasing the time the pulse wave is in the Lo state. Therefore, the electric cutting machine 10 can control the current flowing to the motor 110 so as not to exceed the component ratings of the motor 110 or the switching element 210 by reducing the duty cycle. Furthermore, components can be selected for the motor 110 or the switching element 210 that have ratings that take into account the motor current MImax rather than the maximum current. Therefore, it is possible to suppress cost increases.

[0067] Furthermore, the controller unit 300 switches from the first switching frequency F1 to the second switching frequency F2 when the current flowing to the motor 110 after the motor 110 has started up becomes equal to or greater than the motor current MI1, which is the first threshold. In other words, after the motor 110 is started, the control unit 312 supplies current to the motor 110 at a first switching frequency F1. When the current flowing through the motor 110 becomes greater than or equal to the motor current MI1, the control unit 312 determines that the current is likely to increase further. The control unit 312 then switches from the first switching frequency F1 to the second switching frequency F2 to suppress the current flowing through the motor 110. In this way, the electric cutting machine 10 can determine that the current is likely to increase further when cutting the workpiece CM, and by switching from the first switching frequency F1 to the second switching frequency F2, it can suppress the current flowing to the motor 110. By suppressing the current flowing to the motor 110, the electric cutting machine 10 can continue the processing work. Therefore, it is possible to perform processing work comfortably while keeping cost increases to a minimum.

[0068] Furthermore, the controller unit 300 executes the second control mode M2 ​​when the current flowing to the motor 110 becomes equal to or greater than the motor current MI2, which is the second threshold. In other words, when the current flowing through the motor 110 exceeds the motor current MI2, which is the second threshold, the control unit 312 performs feedback control to control the duty cycle of the second switching frequency F2, thereby suppressing the increase in the current flowing through the motor 110. Therefore, when the current flowing through the motor 110 exceeds the motor current MI2, the control unit 312 determines that the current is likely to increase further in order to cut the workpiece CM. By maintaining the second switching frequency F2 and performing feedback control to reduce the duty cycle, the control unit 312 can control the current flowing through the motor 110 so as not to exceed the component ratings of the motor 110 or the switching element 210. Therefore, it is possible to perform processing work comfortably while keeping cost increases to a minimum.

[0069] Furthermore, after starting the stopped motor 110, the controller unit 300 starts the motor 110 in the first control mode M1, and then, when the motor current MI1 or higher, it controls the motor 110 in the second control mode M2 ​​until a predetermined time PT1, which is the first predetermined time, has elapsed. In other words, the control unit 312 starts the motor 110 in the first control mode M1, and if the current flowing to the motor 110 does not reach the motor current MI2, the execution time of the second control mode M2 ​​is set to a predetermined time PT1, thereby controlling the current flowing to the motor 110 so as not to exceed the component rating of the motor 110 or the switching element 210, while suppressing the temperature rise of the switching element 210. Therefore, by executing the second control mode M2 ​​only for a predetermined time PT1, the control unit 312 can suppress the temperature rise while suppressing the current flowing to electrical components such as the motor 110 or switching element 210. This reduces the need to use components with high heat resistance. Therefore, it is possible to perform processing work comfortably while keeping cost increases to a minimum.

[0070] Furthermore, the controller unit 300 switches to control in the first control mode M1 after control in the second control mode M2 ​​continues for a predetermined time PT2 or longer, which is the second predetermined time. In other words, the control unit 312 prevents the second control mode M2 ​​from continuing for a predetermined time PT2 or longer, thereby limiting the time during which the motor 110 or switching element 210 is overloaded and generates heat. Therefore, the control unit 312 can suppress the temperature rise of the switching element 210 by preventing the control unit 312 from continuing the second control mode M2 ​​for a predetermined time PT2 or longer. This prevents the shortening of the component lifespan of the motor 110 or the switching element 210. Therefore, it is possible to perform processing work comfortably while keeping cost increases to a minimum.

[0071] <Second Embodiment> An electric cutting machine 10A according to a second embodiment of the present invention will be described using Figures 8 to 11.

[0072] The electric cutting machine 10A comprises a housing 20, an inner case 30, and a mounting section 40 for holding a blade BL with a cutting edge as the cutting tool TT. Inside the housing 20 and inner case 30 are a trigger switch section 50, a drive mechanism section 60, a battery section 70, a motor section 100, a drive circuit section 200, and a controller section 300A.

[0073] (Regarding the controller unit 300A) The controller unit 300A detects the current flowing through the motor 110 and controls the current flowing through the motor 110 via the switching element 210. As shown in Figure 8, the controller unit 300A includes a processor 310A and a memory 320. The processor 310A includes a determination unit 311 and a control unit 312A.

[0074] As shown in Figure 9a, when the motor 110 is started with the blade BL pressed against the workpiece CM (hereinafter referred to as the "press-cutting state") and a cutting operation is performed on the workpiece CM, the control unit 312A controls it using the second control mode M2. As shown in Figure 9b, when the motor 110 is started without load to avoid cutting by the blade BL, the control unit 312A does not perform control using the second control mode M2 ​​until at least the predetermined time PT3, which is the third predetermined time, has elapsed after the motor 110 is started.

[0075] Here, for example, as shown in Figure 10a, if the current flowing to the motor 110 becomes greater than the motor current MI5 within a predetermined time PT4, the control unit 312A determines that the motor 110 is started in a state of being switched off. On the other hand, for example, as shown in Figure 10b, if the current flowing to the motor 110 within a predetermined time PT5 does not exceed the motor current MI6, the control unit 312A determines that the motor 110 has been started without load so as not to perform cutting with the blade BL. In this case, the control unit 312A does not perform control by the second control mode M2 ​​until at least the predetermined time PT3, which is the third predetermined time, has elapsed after the motor 110 has been started.

[0076] (Regarding the processing flow of the controller unit 300A) The processing flow of the controller unit 300A will be explained using Figure 11.

[0077] The determination unit 311 in the processor 310 of the controller unit 300 determines whether the trigger 51 is being operated based on the operation information transmitted from the switch unit 52 in the trigger switch unit 50, and the determination unit 311 transmits the result to the control unit 312A via the storage unit 321 (step S310).

[0078] If the determination unit 311 determines that the trigger 51 has not been operated ("NO" in step S310), the control unit 312A proceeds to step S310.

[0079] On the other hand, if the determination unit 311 determines that the trigger 51 has been operated ("YES" in step S310), the control unit 312A sets the control mode to the first control mode M1 (step S320). Then, the control unit 312A causes the time count unit 313 to start counting time (step S330) and transitions the process to step S340.

[0080] The determination unit 311 determines whether or not the motor 110 is rotating based on the information transmitted from the rotation sensor 130 in the motor unit 100 (step S340).

[0081] If the determination unit 311 determines that the motor 110 is rotating (YES in step S340), the control unit 312A proceeds to step S370.

[0082] On the other hand, if the determination unit 311 determines that the motor 110 is not rotating ("NO" in step S340), the control unit 312A obtains time count information from the time count unit 313 (step S350). If the time count information is within the protection stop time TS ("YES" in step S350), the control unit 312A transitions the process to step S340. If the time count information is not within the protection stop time TS ("NO" in step S350), the control unit 312A transitions the process to step S360 and terminates the process by implementing control to stop the current flowing to the motor 110.

[0083] Based on the information from the determination unit 311, the control unit 312A determines whether the motor is in a cut-off state by determining whether the current flowing to the motor 110 within a predetermined time PT4 has become greater than the motor current MI5 (step S370).

[0084] If the control unit 312A determines that the device is in a state of being cut off (YES in step S370), the control unit 312A sets the control mode to the second control mode M2 ​​(step S400) and terminates the process.

[0085] On the other hand, if the control unit 312A determines that it is not in a closed state ("NO" in step S370), the control unit 312A determines whether or not it is in an unloaded state (step S380).

[0086] If the control unit 312A determines that the system is not in an unloaded state ("NO" in step S380), the control unit 312A sets the control mode to the second control mode M2 ​​(step S390) and terminates the process.

[0087] On the other hand, if the control unit 312A determines that there is no load (YES in step S370), the control unit 312A obtains time count information from the time count unit 313 and determines whether or not it is within the predetermined time PT3 (step S390).

[0088] If the control unit 312A determines that the time PT3 is within a predetermined time ("YES" in step S390), the control unit 312A proceeds to step S390.

[0089] On the other hand, if the control unit 312A determines that the time is not within the predetermined time PT3 ("NO" in step S390), the control unit 312A sets the control mode to the second control mode (step S400) and terminates the process.

[0090] (Effects and Benefits) As described above, the electric cutting machine 10A as a work machine according to this second embodiment has a drive mechanism 60 as a transmission mechanism that converts the power of the motor 110 into reciprocating motion and transmits it to the output shaft 43, the tip tool TT is a blade BL with a cutting edge, and when the motor 110 is started with the blade BL pressed against the workpiece CM and cutting work is performed on the workpiece CM, the control unit 312A in the controller unit 300A controls the motor 110 by the second control mode M2, and when the motor 110 is started without load so as not to perform cutting with the blade BL, the control by the second control mode M2 ​​is not performed at least until the predetermined time PT3, which is the third predetermined time, has elapsed after the motor 110 is started. In other words, if the electric cutting machine 10 determines that it is in a cutting state, the control unit 312A in the controller unit 300A switches to the second control mode M2 ​​to control the current flowing to the motor 110 so that the current value does not exceed the rating of the switching element 210 or the rating of the motor 110. If it determines that it is in a no-load state, the control unit 312A limits the time during which the switching element 210 generates heat by not executing the control in the second control mode M2 ​​before the predetermined time PT3 has elapsed. Therefore, the control unit 312 can limit the temperature rise of the switching element 210 when it is switched off or under no-load conditions. This prevents the component life of the switching element 210 from being shortened. Therefore, it is possible to continue machining operations while suppressing cost increases and performance degradation in terms of control.

[0091] Furthermore, the electric cutting machine 10 or electric cutting machine 10A may be equipped with a pressure sensor on the mounting section 40 where the blade BL is attached in order to detect the contact cutting state. In this case, if the control unit 312A obtains information that a pressing force has been applied before current is supplied to the motor 110, the control unit 312A determines that the contact cutting state is in effect. The control unit 312 may detect the pressing force applied to the blade BL based on information obtained from the rotation sensor 130, information obtained from the motor current detection unit 220, information obtained from the time count unit 313, and information obtained from the pressure sensor, and control the current supplied to the motor 110 according to the pressing force. In this case, the electric cutting machine 10 or electric cutting machine 10A can limit the temperature rise of the switching element 210. Furthermore, the electric cutting machine 10 can prevent the component life of the switching element 210 from being shortened.

[0092] (modified version) As shown in Figure 12a, after starting the stopped motor 110, if the current flowing through the motor 110 becomes a motor current MI3 which is less than the motor current MI1, the control unit 312 in the controller unit 300 may control in the first control mode M1. Also, as shown in Figure 12b, if the current flowing through the motor 110 becomes greater than the motor current MI1 but becomes a motor current MI4 which is less than the motor current MI2 without reaching the motor current MI2, the control unit 312 in the controller unit 300 does not need to perform feedback control in the second control mode M2. At this time, the motor currents MI1 to MI4 are set to satisfy the relationship shown in Equation 1 below.

number

[0093] 10: Electric cutting machine (work machine) 20: Housing 30: Inner Case 40: Mounting part 50: Trigger switch section 60: Drive mechanism 100: Motor section 110: Motor 120: Rotation sensor 200: Drive circuit section 210: Switching element 300: Controller section 300A: Controller section 310: Processor 310A: Processor 311: Judgment section 312: Control Unit 312A: Control Unit 313: Time count section 320: Memory 321: Storage section

Claims

1. Motor and, The output shaft connected to the motor and holding the tip tool, A switching element that rotates the motor by supplying current to the motor, A controller unit that detects the current flowing through the motor and controls the current flowing through the motor via the switching element, Equipped with, The controller unit is A first control mode that controls the current flowing through the motor by a first switching frequency, A second control mode controls the current flowing through the motor using a second switching frequency that is higher than the first switching frequency, and also performs feedback control to prevent the current flowing through the motor from exceeding a predetermined value. A work machine configured to be executable.

2. The work machine according to claim 1, wherein the controller unit performs the feedback control by controlling the duty cycle of the second switching frequency in the second control mode.

3. The work machine according to claim 2, wherein the controller unit switches from the first switching frequency to the second switching frequency when the current flowing to the motor after the motor has been started exceeds a first threshold.

4. The work machine according to claim 3, wherein the controller unit executes the second control mode when the current flowing to the motor exceeds a second threshold.

5. The work machine according to any one of claims 2 to 4, wherein the controller unit, after starting the motor in a stopped state in the first control mode, switches to the second control mode, and then controls the motor in the second control mode until a first predetermined time has elapsed.

6. The work machine according to claim 1, wherein the controller unit switches to control by the first control mode after control by the second control mode continues for a second predetermined time or longer.

7. The motor has a transmission mechanism that converts the motor's power into reciprocating motion and transmits it to the output shaft. The aforementioned tip tool is a blade with an edge, When the motor is started with the blade pressed against the workpiece and a cutting operation is performed on the workpiece, the motor is controlled by the second control mode. The work machine according to claim 1, wherein if the motor is started without load so as not to perform cutting with the blade, the control by the second control mode is not performed at least until a third predetermined time has elapsed after the motor has been started.

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