Work machine

Abstract

To provide a work machine capable of increasing a brake time after power shutdown.SOLUTION: A control part 20, when a trigger 11 is turned on and a battery pack 5 is mounted, drives a motor 31. The control part 20, when a voltage of a battery temperature detection terminal 28 is 0 V, determines that the battery pack 5 is disengaged, turns switching elements Q1 to Q3 off, turns switching elements Q4 to Q6 on, and applies electric brake to the motor 31. The control part 20, when a lower side gate voltage is reduced to a threshold, turns all of switching element driving signals H1 to H6 off. The control part 20, when the lower side gate voltage is recovered, carries out brake control again.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] There are known working machines that are driven by commercial power sources or DC power sources. Patent Document 1 discloses a working machine that is driven by a storage battery as a DC power source, specifically an electric grass cutter. When the storage battery falls off during operation, the working machine of Patent Document 1 operates a control operation unit using the charge stored in an electrolytic capacitor, and the control operation unit controls a switching element to short-circuit the drive coil, brakes the motor, and forcibly stops the rotary blade. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-125056 A Summary of the Invention [Problem to be solved by the invention]

[0004] The configuration of Patent Document 1 does not take into consideration the case where the charge stored in the electrolytic capacitor becomes low (the voltage of the electrolytic capacitor becomes low). Furthermore, in the configuration of Patent Document 1, in order to detect the removal of the storage battery when the voltage of the terminal to which the storage battery voltage is input falls below a predetermined value, a diode is provided to prevent the regenerative energy of the motor from flowing to the storage battery side and causing erroneous detection. If this diode is present, the control operation unit cannot be operated by the regenerative energy of the motor. On the other hand, if this diode is removed, the voltage rise caused by the regenerative energy of the motor makes it impossible to detect the removal of the storage battery.

[0005] An object of the present invention is to solve at least one of the following problems 1 to 3. Problem 1: To provide a work machine capable of extending the braking time after the power is cut off. Problem 2: To provide a work machine capable of increasing the reliability of detecting a power interruption. Challenge 3: To provide a work machine that can perform optimal braking according to the situation. [Means for solving the problem]

[0006] One aspect of the present invention is a work machine. A motor driven by power supplied from a power supply; an operation unit that is operated by an operator to instruct starting and stopping of the motor; a drive unit having a switching element and driving the motor in response to an operation of the operation unit; A control unit that controls the drive unit; A work machine comprising: The control unit is configured to execute a third brake control when the power supply is cut off while the motor is rotating, and then, when the control voltage applied to the control terminal of the switching element decreases, execute a fourth brake control different from the third brake control.

[0007] Another aspect of the present invention is a work machine. A motor; an operation unit that is operated by an operator to instruct starting and stopping of the motor; a drive unit that drives the motor in response to an operation of the operation unit; A control unit that controls the drive unit; a housing to which a battery pack serving as a driving source for the motor can be detachably attached; A work machine comprising: The control unit is configured to control the drive unit so that the braking force applied to the motor is different between a first state in which the operating unit is operated and then the operation of the operating unit is released, and a second state in which the battery pack is detached from the housing while the motor is rotating.

[0008] Another aspect of the present invention is a work machine. A motor driven by power supplied from a power supply; an operation unit that is operated by an operator to instruct starting and stopping of the motor; a drive unit having a switching element and driving the motor in response to an operation of the operation unit; A voltage detection unit that detects a voltage on an input side of the drive unit; A control unit that controls the drive unit; A work machine comprising: The control unit is configured to apply a brake to the motor when the voltage detected by the voltage detection unit increases.

[0009] Another aspect of the present invention is a work machine. A motor driven by power supplied from a power supply; an operation unit that is operated by an operator to instruct starting and stopping of the motor; a drive unit having a switching element and driving the motor in response to an operation of the operation unit; a temperature terminal to which temperature information of the power supply is input; A control unit that controls the drive unit; A work machine comprising: The control unit is configured to detect a cutoff of the power supply based on information input from the temperature terminal.

[0010] The present invention may be expressed as an "electric operating machine", "electric tool", "electrical equipment", etc., and such expressions are also valid as aspects of the present invention. Effect of the Invention

[0011] According to the present invention, at least one of the above problems 1 to 3 can be achieved. [Brief description of the drawings]

[0012] [Figure 1] 1 is a circuit block diagram of a work machine 1 according to an embodiment of the present invention. [Diagram 2] FIG. 3 is a cross-sectional view of the motor 3 of the work machine 1. [Diagram 3]5 is a time chart for when the trigger 11 is turned off while the motor 31 is being driven in the work machine 1. [Figure 4] 4 is a time chart relating to a first control example of the work machine 1. [Diagram 5] 5 is a time chart relating to a second control example of the work machine 1. [Figure 6] 6 is a flowchart of a third control example of the work machine 1. [Figure 7] 13 is a flowchart of a fourth control example of the work machine 1. [Figure 8] 6 is a time chart relating to a third control example of the work machine 1. [Figure 9] 6 is a time chart relating to a fourth control example of the work machine 1. [Figure 10] 4 is a diagram showing the change over time in the direction of a phase current after the trigger 11 is turned off while the motor 31 is being driven in the work machine 1. FIG. [Figure 11] 9 is a diagram showing the direction of phase current in each section AF of the time chart of FIG. 8; [Figure 12] 10 is a diagram showing the direction of phase current in each section AF of the time chart of FIG. 9; [Figure 13] FIG. 2 is a side view of a portable circular saw as an example of the work machine 1. [Figure 14] 1 is a perspective view of a brush cutter as an example of a work machine 1. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] This embodiment relates to a working machine 1. The working machine 1 is, for example, a portable circular saw as shown in Fig. 13 or a brush cutter as shown in Fig. 14, and has a housing 10 and a trigger 11 as an operating unit. A battery pack 5 serving as a power source is removably attached to the housing 10. The mechanical configurations of portable circular saws and brush cutters are well known, so a description thereof will be omitted here. The circuit configuration of the working machine 1 will be described below.

[0014] 1 is a circuit block diagram of a work machine 1. The work machine 1 includes a motor 31, an inverter circuit 30, and a control unit 20.

[0015] The motor 31 is driven by power supplied from the battery pack 5. The motor 31 is a 4-pole, 6-slot, inner rotor type, three-phase brushless motor as shown in FIG. 2, and has a stator 32 and a rotor 33. The stator 32 has U-phase, V-phase, and W-phase stator windings 34 that are star-connected (Y-connected). An operator can instruct the motor 31 to start and stop by operating the trigger 11.

[0016] The inverter circuit 30 is a drive unit that drives the motor 31 in response to the operation of the trigger 11 under the control of the control unit 20. The inverter circuit 30 converts the direct current output by the battery pack 5 into alternating current and supplies it to each stator winding 34 of the stator 32 to drive the motor 31. An electrolytic capacitor C for absorbing surges is provided between the input terminals of the inverter circuit 30. The inverter circuit 30 includes switching elements Q1 to Q6 such as FETs and IGBTs connected in a three-phase bridge.

[0017] The sources of the switching elements Q1 to Q3 and the drains of the switching elements Q4 to Q6 are connected to each other and to star-connected stator windings U, V, and W. Parasitic diodes D1 to D6 are present in parallel between the drain and source of each of the switching elements Q1 to Q6.

[0018] The switching elements Q1 to Q6 are turned on when the input voltage to their gates (control terminals) is at high level, and turned off when the input voltage is at low level. The on / off of the switching elements Q1 to Q6 is controlled by the control unit 20.

[0019] The gates of the switching elements Q1 to Q6 are connected to the inverter drive unit 25 of the control unit 20. The switching elements Q1 to Q6 perform switching operations in response to switching element drive signals H1 to H6 input from the inverter drive unit 25. As a result, the DC voltage from the battery pack 5 applied to the inverter circuit 30 is supplied as a three-phase AC voltage to the U-phase, V-phase, and W-phase stator windings.

[0020] The inverter circuit 30 employs a known 120-degree energization (rectangular wave drive) method, in which the upper (high-voltage side) switching elements Q1-Q3 connected to an upper arm (high-voltage line) are turned on in sequence for 120 degrees each out of one 360-degree cycle, and the lower (low-voltage side) switching elements Q4-Q6 connected to a lower arm (low-voltage line) are also turned on in sequence for 120 degrees each out of one 360-degree cycle. During the on period, at least one of the upper switching elements Q1-Q3 and the lower switching elements Q4-Q6 may be PWM (Pulse Width Modulation) controlled.

[0021] The current detection circuit 12 detects the drive current of the motor 31 from the voltage of a resistor R provided in the path of the drive current of the motor 31 (the current flowing through each stator winding 34 of the stator 32), and transmits the detected drive current to the control unit 20.

[0022] The battery voltage detection circuit 13, which serves as a voltage detection unit, detects the output voltage of the battery pack 5 (the voltage on the input side of the inverter circuit 30) and transmits it to the control unit 20. The voltage detection value in the battery voltage detection circuit 13 becomes the output voltage of the battery pack 5 (hereinafter "battery voltage") when the battery pack 5 is connected. On the other hand, if the battery pack 5 is removed while the motor 31 is being driven (rotating), the voltage detection value in the battery voltage detection circuit 13 rises above the battery voltage due to regenerative energy of the motor 31. Therefore, when the voltage detected by the battery voltage detection circuit 13 rises above the expected battery voltage, the control unit 20 can determine that the battery pack 5 has been removed (detect a power interruption).

[0023] The temperature detection element 15 is, for example, a thermistor, and is provided near the motor 31 or the inverter circuit 30. The temperature detection circuit 16 detects the temperature of the motor 31 or the inverter circuit 30 based on the output voltage of the temperature detection element 15, and transmits the temperature to the control unit 20.

[0024] The Hall ICs 19 are an example of a magnetic detection element, and three are arranged at 60° intervals in the circumferential direction as shown in Fig. 2. INT1-INT3 shown in Fig. 2 are output signals from each Hall IC 19, and waveforms are shown in Figs. 8-9 described below. The rotor position detection circuit 17 detects the rotational position of the rotor 33 (hereinafter referred to as "motor rotational position") from the output signal of the Hall IC 19 and transmits it to the control unit 20. The control unit 20 can detect the rotation speed of the motor 31 (hereinafter referred to as "motor rotation speed") from the signal from the rotor position detection circuit 17.

[0025] The switch mechanism 18 transmits a switch operation detection signal corresponding to the operation of the trigger 11 by an operator to the control unit 20. The switch mechanism 18 also includes a contact switch SW provided between the positive terminal of the battery pack 5 and the upper input terminal of the inverter circuit 30 and the high-voltage terminal of the electrolytic capacitor C. The contact switch SW is switched on and off in response to the operation of the trigger 11.

[0026] A diode D7 is connected in parallel to the contact switch SW. The diode D7 is connected in a direction that allows current to flow from the inverter circuit 30 to the battery pack 5. The presence of the diode D7 allows the regenerative energy of the motor 31 to flow to the gate voltage generation circuit 22 and the control circuit power generation circuit 24 when the battery pack 5 is removed from the housing 10 with the contact switch SW in the off state, and the control unit 20 can be maintained in an activated state.

[0027] The gate voltage generation circuit 22 generates an upper gate voltage to be applied to the gates of the switching elements Q1 to Q3 and a lower gate voltage to be applied to the gates of the switching elements Q4 to Q6 based on the battery voltage.

[0028] The control circuit power generation circuit 24 converts the output voltage of the gate voltage generation circuit 22 into a power supply voltage for the control unit 20, etc., and supplies it to the control unit 20, etc. The gate voltage detection circuit 26 detects the output voltage of the gate voltage generation circuit 22 and transmits it to the control unit 20.

[0029] The battery temperature detection circuit 27 detects the temperature of the battery pack 5 from the voltage of the battery temperature detection terminal 28, i.e., the output signal of the temperature detection element 7 of the battery pack 5, and transmits it to the control unit 20. The battery temperature detection terminal 28 is a temperature terminal to which temperature information of the battery pack 5 is input. The voltage of the battery temperature detection terminal 28 has a voltage value of about 2.8 V when the battery pack 5 is connected, and a voltage value corresponding to the temperature of the battery pack 5. On the other hand, the voltage of the battery temperature detection terminal 28 is 0 V when the battery pack 5 is not connected. Therefore, the control unit 20 can determine whether the battery pack 5 is connected or not, i.e., whether the power supply has been cut off or not, from the voltage of the battery temperature detection terminal 28.

[0030] In the work machine 1, the battery temperature detection terminal 28 detects the temperature of the battery pack 5, and also functions as a battery attachment detection terminal that detects whether the battery pack 5 is connected as described above. Furthermore, the battery temperature detection terminal 28 also functions as a communication terminal between the battery pack 5 and the control unit 20. That is, the work machine 1 is configured to perform both digital and analog communication between the control unit 20 and the battery pack 5, and can detect temperature information and communicate information (digital communication) via the battery temperature detection terminal 28 by switching between digital communication and analog communication at any timing. Note that, in order to improve the accuracy of detecting the removal of the battery pack 5, the control unit 20 may periodically check the communication state with the battery pack 5 via the battery temperature detection terminal 28 in addition to detecting the temperature, and may determine that the battery pack 5 has been removed from the housing 10 even if communication is not established.

[0031] The control unit 20 controls the inverter circuit 30 in response to the operation of the trigger 11, and controls the driving of the motor 31. The control unit 20 includes a calculation unit 21 and an inverter driving unit 25 (a pre-driver circuit).

[0032] The calculation unit 21 generates a gate control signal based on the signal from the rotor position detection circuit 17, and outputs it to the inverter drive unit 25. There are six gate control signals corresponding to the switching elements Q1 to Q6 of the inverter circuit 30, and each of the gate control signals is a binary signal that goes to a high level when switching elements Q1 to Q6 are turned on and goes to a low level when switching elements Q1 to Q6 are turned off.

[0033] The inverter drive unit 25 generates switching element drive signals H1 to H6 with increased current capabilities of each gate control signal based on the output voltage of the gate voltage generation circuit 22, and outputs them to the gates (control terminals) of the switching elements Q1 to Q6 of the inverter circuit 30. The switching element drive signals H1 to H6 are at a high level when the corresponding gate control signal is at a high level, and are at a low level when the corresponding gate control signal is at a low level.

[0034] 3 is a time chart for a case where the trigger 11 is turned off while the motor 31 is being driven in the work machine 1. Before time t1, the trigger 11 is on and the control unit 20 drives the motor 31.

[0035] When the trigger 11 turns off at time t1, the first state is entered, and the control unit 20 sets the switching element drive signals H1-H3 applied to the gates of the upper switching elements Q1-Q3 to low level, and sets the switching element drive signals H4-H6 applied to the gates of the lower switching elements Q4-Q6 to high level. This turns the upper switching elements Q1-Q3 off and the lower switching elements Q4-Q6 on, and an electric brake is applied to the motor 31. The brake control started at time t1 corresponds to the first brake control.

[0036] 4 is a time chart relating to a first control example of the work machine 1. Before time t2, the trigger 11 is on, the battery pack 5 is attached, and the control unit 20 drives the motor 31.

[0037] When the battery pack 5 is removed from the housing 10 at time t2, the voltage of the battery temperature detection terminal 28 becomes 0 V (a voltage value indicating power cutoff). Even if the battery pack 5 is removed from the housing 10, the gate voltage generation circuit 22 and the control circuit power generation circuit 24 operate using the power stored in the electrolytic capacitor C, and the control unit 20 remains activated.

[0038] When the control unit 20 detects from the voltage of the battery temperature detection terminal 28 that the battery pack 5 has been removed from the housing 10 at time t2, it sets the switching element drive signals H1 to H3 to low level and the switching element drive signals H4 to H6 to high level, turning off the switching elements Q1 to Q3 and turning on the switching elements Q4 to Q6, and applying an electric brake to the motor 31.

[0039] After time t2, the energy stored in electrolytic capacitor C gradually decreases. The lower gate voltage is maintained at 15V until time t3, but the energy stored in electrolytic capacitor C continues to decrease, and the voltage gradually decreases from 15V after time t3. The lower gate voltage becomes the voltage of the switching element drive signals H4 to H6 when they are at a high level. Therefore, the voltages of the switching element drive signals H4 to H6 also decrease in conjunction with the decrease in the lower gate voltage.

[0040] When the lower gate voltage drops to the threshold value at time t4, the control unit 20 turns off all of the switching element drive signals H1 to H6. This causes the electrolytic capacitor C to be charged with the regenerative energy of the motor 31, and the input voltages to the gate voltage generation circuit 22 and the control circuit power generation circuit 24 are restored, and the lower gate voltage is also restored.

[0041] When the lower gate voltage rises to a predetermined value at time t5, the control unit 20 performs the same brake control as that started at time t2. After that, the same operation as that from time t2 to t5 is repeated until the motor 31 stops.

[0042] Fig. 5 is a time chart relating to a second control example of the work machine 1. The second control example is different from the first control example in the number of switching elements of the inverter circuit 30 that are turned on in the brake control after the battery pack 5 is detached from the housing 10. The operation up to time t12 in Fig. 5 is the same as the operation up to time t2 in Fig. 4.

[0043] When the battery pack 5 is removed from the housing 10 at time t12, the second state is entered. When the removal of the battery pack 5 from the housing 10 is detected by the voltage of the battery temperature detection terminal 28, the control unit 20 sets the switching element drive signals H1 to H3, H6 to a low level and the switching element drive signals H4, H5 to a high level. This turns off the switching elements Q1 to Q3, Q6 and turns on the switching elements Q4, Q5, and electrically brakes the motor 31. Compared to the brake control started at time t2 in FIG. 4, the brake control started at time t12 (corresponding to the second brake control) has a smaller braking force because fewer switching elements are turned on, but the consumption of the energy stored in the electrolytic capacitor C is also smaller.

[0044] After time t12, the energy stored in the electrolytic capacitor C gradually decreases. The lower gate voltage is maintained at 15V until time t13, but the energy stored in the electrolytic capacitor C continues to decrease, and after time t13, it gradually decreases from 15V. The voltage levels of the switching element drive signals H4 and H5 also decrease in conjunction with the decrease in the lower gate voltage. The period from time t12 to t13 is longer than the period from time t2 to t3 in FIG. 4. This is due to the difference in the amount of energy consumed by the brake control during both periods.

[0045] When the lower gate voltage drops to the threshold value at time t14, the control unit 20 turns off all of the switching element drive signals H1 to H6. This causes the electrolytic capacitor C to be charged with the regenerative energy of the motor 31, and the input voltages to the gate voltage generation circuit 22 and the control circuit power generation circuit 24 are restored, and the lower gate voltage is also restored.

[0046] When the lower gate voltage rises to a predetermined value at time t15, the control unit 20 performs the same brake control as that started at time t12. After that, the same operation as that from time t12 to t15 is repeated until the motor 31 stops.

[0047] 6 is a flowchart of a third control example of the work machine 1. The control unit 20 drives the motor 31 (S1), and when the voltage of the battery temperature detection terminal 28 drops below the threshold value (YES in S5) while the trigger 11 is on (NO in S3), it determines that the battery pack 5 has been removed from the housing 10, and performs brake control (S7). The threshold value in S5 is set lower than the voltage range that can be input to the battery temperature detection terminal 28 when the battery pack 5 is connected.

[0048] When the trigger 11 is off in S3 (YES in S3), the control unit 20 performs brake control (S7). The brake control in S7 is the same as the brake control started at time t2 in Fig. 4, and applies electric brakes by turning off the switching elements Q1 to Q3 and turning on the switching elements Q4 to Q6.

[0049] If the motor rotation speed is not less than the threshold value (NO in S9), the control unit 20 determines that the motor 31 is not stopped, and proceeds to S11. If the lower side gate voltage is not less than the threshold value (NO in S11), the control unit 20 determines that the switching elements Q4 to Q6 are not in the half-on state, and continues the brake control (S7). If the lower side gate voltage is less than the threshold value (YES in S11), the control unit 20 determines that the switching elements Q4 to Q6 are in the half-on state, and performs the off control in S13 and subsequent steps. The half-on state is a state in which the switching elements are not completely on due to a low lower side gate voltage, and the on-resistance is high.

[0050] The control unit 20 detects the motor rotation position from the combination of the output signals of the Hall IC 19 (S13).

[0051] The control unit 20 determines whether the combination of the output signals of the Hall IC 19 is U phase (INT1): L, V phase (INT2): H, W phase (INT3): H If so (YES in S15), the switching element Q6 is turned off (S17), and the process returns to S11.

[0052] The control unit 20 determines whether the combination of the output signals of the Hall IC 19 is U phase (INT1): H, V phase (INT2): H, W phase (INT3): L, If so (YES in S19), the switching element Q5 is turned off (S21), and the process returns to S11.

[0053] The control unit 20 determines whether the combination of the output signals of the Hall IC 19 is U phase (INT1): H, V phase (INT2): L, W phase (INT3): H, If so (YES in S23), the switching element Q4 is turned off (S25), and the process returns to S11.

[0054] 7 is a flowchart of a fourth control example of the work machine 1. The control unit 20 drives the motor 31 (S1), and when the trigger 11 is on (NO in S3) and the voltage detection value in the battery voltage detection circuit 13 exceeds the threshold value (YES in S5a), it determines that the battery pack 5 has been removed from the housing 10 and performs brake control (S7a). The threshold value in S5a is higher than the expected voltage range of the battery voltage, for example, 55V.

[0055] The brake control in S7a is the same as the brake control started at time t12 in FIG. 5, and applies electric brakes by turning off switching elements Q1 to Q3 and Q6 and turning on switching elements Q4 and Q5.

[0056] If the trigger 11 is off in S3 (YES in S3), the control unit 20 performs brake control (S4) and proceeds to S5a. The brake control in S4 is the same as S7 in Fig. 6, and applies electric brakes by turning off the switching elements Q1 to Q3 and turning on the switching elements Q4 to Q6. In the brake control in S4, the switching elements Q4 to Q6 may be turned on intermittently (PWM control). If the condition in S5a is satisfied during the brake control in S4 (if the battery pack 5 is removed from the housing 10), the control unit 20 transitions to brake control in S7a.

[0057] If the motor rotation speed is not less than the threshold (NO in S9), the control unit 20 determines that the motor 31 is not stopped, and proceeds to S11. If the lower gate voltage is not less than the threshold (NO in S11), the control unit 20 determines that the switching elements Q4 and Q5 are not in the half-on state, and continues the brake control (S7a). If the lower gate voltage is less than the threshold (YES in S11), the control unit 20 determines that the switching elements Q4 and Q5 are in the half-on state, and performs the off control from S13 onwards. The off control is the off control in FIG. 6 excluding the processing for Q6 that is already off (S15, S17).

[0058] Fig. 8 is a time chart relating to a third control example of the work machine 1. Although not shown in the figure, in Fig. 8 the trigger 11 is always on. Before time t21, the trigger 11 is on, the battery pack 5 is attached, and the control unit 20 drives the motor 31.

[0059] When the battery pack 5 is removed from the housing 10 at time t21, the voltage of the battery temperature detection terminal 28 becomes 0 V (a voltage value indicating power cutoff). Even if the battery pack 5 is removed from the housing 10, the gate voltage generation circuit 22 and the control circuit power generation circuit 24 operate using the power stored in the electrolytic capacitor C, and the control unit 20 remains activated.

[0060] When the control unit 20 detects at time t21 that the battery pack 5 has been removed from the housing 10 based on the voltage at the battery temperature detection terminal 28, the control unit 20 sets the switching element drive signals H1 to H3 to a low level and the switching element drive signals H4 to H6 to a high level, thereby turning off the switching elements Q1 to Q3 and turning on the switching elements Q4 to Q6, and applying an electric brake to the motor 31.

[0061] When the lower gate voltage falls below the threshold at time t23, the control unit 20 performs off control (corresponding to the process after S13 in FIG. 6) to sequentially turn off the switching elements Q4 to Q6.

[0062] The control unit 20 sets the switching element drive signal H6 to low level at the timing (time t25) when the output signal (INT2) of the V-phase Hall IC 19 rises. This turns off the switching element Q6. The current that had been flowing through the switching element Q6 now flows via the diode D3 of the switching element Q3.

[0063] The control unit 20 then sets the switching element drive signal H5 to low level at the timing (time t27) when the output signal (INT1) of the Hall IC 19 for the U phase rises. This turns off the switching element Q5. The current that had been flowing through the switching element Q5 now flows via the diode D2 of the switching element Q2.

[0064] The control unit 20 then sets the switching element drive signal H4 to low level at the timing (time t29) when the output signal (INT3) of the W-phase Hall IC 19 rises. This turns off the switching element Q4. The current that had been flowing through the switching element Q4 now flows via the diode D1 of the switching element Q1.

[0065] The order in which the switching elements Q4 to Q6 are turned off varies depending on the motor rotational position when the lower gate voltage falls below the threshold.

[0066] The brake control is performed with the switching elements Q4 and Q5 in the on state (conducting state) from time t25 to t27, and with the switching element Q4 in the on state from time t27 to t29. The brake control with the switching elements Q4 to Q6 in the on state corresponds to the third brake control, and the brake control with the switching elements Q4 and Q5 in the on state and the brake control with the switching element Q4 in the on state correspond to the fourth brake control. Alternatively, the brake control with the switching elements Q4 to Q6 in the on state and the brake control with the switching elements Q4 and Q5 in the on state correspond to the third brake control, and the brake control with the switching element Q4 in the on state corresponds to the fourth brake control. The fourth brake control has a weaker braking force than the third brake control.

[0067] At time t29, all of the switching elements Q4 to Q6 are turned off, the electrolytic capacitor C is charged with the regenerative energy of the motor 31, the input voltages to the gate voltage generation circuit 22 and the control circuit power generation circuit 24 are restored, and the lower gate voltage is also restored.

[0068] When the lower gate voltage rises to or above the threshold at time t31, the control unit 20 performs the same brake control as that started at time t21. After that, the same operation from time t21 to t31 is repeated until the motor 31 stops.

[0069] 9 is a time chart relating to the fourth control example of the work machine 1. Before time t41, the trigger 11 is on, the battery pack 5 is attached, and the control unit 20 drives the motor 31.

[0070] When the trigger 11 turns off at time t41, the first brake section begins, and the control unit 20 sets the switching element drive signals H1 to H3 to low level and the switching element drive signals H4 to H6 to intermittently high level, thereby turning off the switching elements Q1 to Q3 and intermittently turning on the switching elements Q4 to Q6, and applying an electric brake to the motor 31.

[0071] In the middle of the first braking section from time t41, the battery pack 5 becomes detached from the housing 10, and the voltage on the input side of the inverter circuit 30 (hereinafter, "inverter input voltage") starts to rise.

[0072] When the inverter input voltage exceeds the threshold value of 55V at time t43, the second braking section begins, and the control unit 20 sets the switching element drive signals H1 to H3, and H6 to low level and the switching element drive signals H4 and H5 to high level. This turns off the switching elements Q1 to Q3, and Q6 and turns on the switching elements Q4 and Q5, and the motor 31 is electrically braked.

[0073] When the lower gate voltage falls below the threshold at time t45, the control unit 20 performs off control (corresponding to the process after S13 in FIG. 7) to sequentially turn off the switching elements Q4 and Q5.

[0074] The control unit 20 sets the switching element drive signal H5 to low level at the timing (time t47) when the output signal (INT1) of the Hall IC 19 for the U phase rises. This turns off the switching element Q5. The current that had been flowing through the switching element Q5 now flows via the diode D2 of the switching element Q2.

[0075] The control unit 20 then sets the switching element drive signal H4 to low level at the timing (time t49) when the output signal (INT3) of the W-phase Hall IC 19 rises. This turns off the switching element Q4. The current that had been flowing through the switching element Q4 now flows via the diode D1 of the switching element Q1.

[0076] The order in which the switching elements Q4 and Q5 are turned off varies depending on the motor rotational position when the lower gate voltage falls below the threshold.

[0077] During the period from time t47 to t49, braking control is performed with switching element Q4 in the on state. The braking control with switching elements Q4 and Q5 in the on state corresponds to the third braking control, and the braking control with switching element Q4 in the on state corresponds to the fourth braking control. The fourth braking control has a weaker braking force than the third braking control.

[0078] At time t49, both switching elements Q4 and Q5 are turned off, the electrolytic capacitor C is charged with the regenerative energy of the motor 31, the input voltages to the gate voltage generation circuit 22 and the control circuit power generation circuit 24 are restored, and the lower gate voltage is also restored.

[0079] When the lower gate voltage rises to or above the threshold at time t51, the control unit 20 performs the same brake control as that started at time t43. After that, the same operation as that from time t43 to t51 is repeated until the motor 31 stops.

[0080] 10(A) to 10(F) are diagrams showing changes over time in the direction of phase currents (regenerative currents) after the trigger 11 is turned off while the motor 31 is being driven in the work machine 1. The direction of the phase currents changes sequentially with the rotation of the motor 31. The phase currents flow in a closed loop between the switching elements Q4 to Q6 and the stator 32.

[0081] 11(A) to (F) are diagrams showing the directions of phase currents (regenerative currents) in each section AF of the time chart in FIG. 8. Between FIG. 11(B) and (C), there is a timing when the direction of the W-phase current changes from a direction flowing out from the stator 32 side to a direction flowing into the stator 32 side, and the switching element Q6 is turned off at that timing. Between FIG. 11(D) and (E), there is a timing when the direction of the V-phase current changes from a direction flowing out from the stator 32 side to a direction flowing into the stator 32 side, and the switching element Q5 is turned off at that timing. After FIG. 11(F), there is a timing when the direction of the U-phase current changes from a direction flowing out from the stator 32 side to a direction flowing into the stator 32 side, and the switching element Q4 is turned off at that timing.

[0082] 12(A)-(F) are diagrams showing the directions of phase currents (regenerative currents) in each section AF of the time chart in FIG. 9. In FIG. 12(A)-(F), since switching element Q6 is always off, no current flows from the drain side to the source side of switching element Q6. Between FIG. 12(D) and (E), there is a timing when the direction of the V-phase current changes from the direction flowing out from the stator 32 side to the direction flowing into the stator 32 side, and switching element Q5 is turned off at that timing. In addition, after FIG. 12(F), there is a timing when the direction of the U-phase current changes from the direction flowing out from the stator 32 side to the direction flowing into the stator 32 side, and switching element Q4 is turned off at that timing.

[0083] This embodiment provides the following advantages.

[0084] (1) The work machine 1 has a diode D7 in parallel with the contact switch SW. When the contact switch SW is off and the battery pack 5 is removed from the housing 10, the regenerative energy of the motor 31 is passed through the diode D7 to the gate voltage generation circuit 22 and the control circuit power generation circuit 24. This ensures that the power supply for the control unit 20 is maintained for a long period of time, and the control unit 20 can be kept activated for a long period of time.

[0085] (2) The control unit 20 judges whether the battery pack 5 has been removed from the housing 10 based on the voltage at the battery temperature detection terminal 28 or the inverter input voltage. Therefore, unlike a configuration in which the battery pack 5 is judged to have been removed from the housing 10 when the voltage at the terminal to which the output voltage of the battery pack 5 is input falls below a predetermined value, there is no need to provide a diode (such as the diode 51 in Patent Document 1) to prevent the regenerative energy of the motor 31 from flowing to the battery pack 5 side and causing erroneous detection. Therefore, when the battery pack 5 is removed from the housing 10, the regenerative energy of the motor 31 can be flowed to the gate voltage generation circuit 22 and the control circuit power generation circuit 24, and the activated state of the control unit 20 can be maintained for a long time.

[0086] (3) In the first to third control examples shown in Fig. 4 to Fig. 6 and Fig. 8, the control unit 20 determines that the battery pack 5 has been removed from the housing 10 when the voltage of the battery temperature detection terminal 28 becomes equal to or lower than a threshold value, for example, 0 V. This allows the single battery temperature detection terminal 28 to perform three functions: temperature detection, communication, and battery attachment detection. This allows the number of terminals to be increased without increasing the number of terminals (while maintaining compatibility with conventional terminals) and while suppressing an increase in size.

[0087] (4) In a fourth control example shown in Fig. 7 and Fig. 9, the control unit 20 determines that the battery pack 5 has been removed from the housing 10 when the inverter input voltage exceeds a threshold value. This reduces the risk of erroneous detection due to loose terminal connections between the battery pack 5 and the main body of the work machine 1. In addition, by setting the threshold value of the inverter input voltage to, for example, 55V, it is possible to appropriately handle cases in which the rated voltage of the battery pack 5 is 18V or 36V.

[0088] (5) When the lower gate voltage falls below the threshold during execution of the brake control after the battery pack 5 is removed from the housing 10, the control unit 20 temporarily turns off all of the switching elements Q4 to Q6. This makes it possible to suppress heat generation in the switching elements caused by current flowing in the half-on state, thereby suppressing damage to the switching elements. Furthermore, when the lower gate voltage recovers due to the regenerative energy of the motor 31, the control unit 20 resumes the brake control. This makes it possible to secure a longer total brake control time and increase the reliability of stopping the motor 31.

[0089] 6 to 9, when the lower gate voltage falls below the threshold and the control unit 20 turns off all of the switching elements Q4 to Q6, the control unit 20 turns off the switching element through which the phase current flows at the timing when the direction of the phase current changes from flowing out from the stator 32 side to flowing into the stator 32 side. This makes it possible to suppress a voltage rise due to regenerative energy.

[0090] (7) In the second and fourth control examples shown in FIG. 5, FIG. 7, and FIG. 9, the control unit 20 turns off the switching elements Q1 to Q3 and Q6 and turns on the switching elements Q4 and Q5 in the brake control after the battery pack 5 is removed from the housing 10. Therefore, compared with the brake control in which the switching elements Q1 to Q3 are turned off and the switching elements Q4 to Q6 are turned on, the drop in the lower gate voltage can be suppressed and the time until the lower gate voltage drops below the threshold, that is, the duration of one brake control, can be extended. As a result, when the lower gate voltage drops below the threshold and all the switching elements Q4 to Q6 are turned off, the phase current is sufficiently small, and the voltage rise due to the regenerative energy is suppressed. Furthermore, when the trigger 11 is turned off when the battery pack 5 is not removed from the housing 10, the control unit 20 performs the brake control in which the switching elements Q1 to Q3 are turned off and the switching elements Q4 to Q6 are turned on, thereby ensuring a high brake force. In this way, appropriate brake control according to the usage situation of the work machine 1 can be executed.

[0091] 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 each of the details specifically described in the embodiment within the scope of the claims.

[0092] The voltage values, the number of poles and the number of slots of the motor 31, etc., given as specific numerical values ​​in the embodiment do not limit the scope of the invention in any way and can be changed as desired according to the required specifications. The working machine of the present invention is not limited to a portable circular saw or a brush cutter, but may be of other types such as a table circular saw or a grinder. [Explanation of symbols]

[0093] 1...work machine, 5...battery pack, 7...temperature detection element, 10...housing, 11...trigger (operation unit), 12...current detection circuit, 13...battery voltage detection circuit, 15...temperature detection element, 16...temperature detection circuit, 17...rotor position detection circuit, 18...switch mechanism, 19...Hall IC, 20...control unit, 21...calculation unit, 22...gate voltage generation circuit, 24...control circuit power generation circuit, 25...inverter drive unit (pre-driver circuit), 26...gate voltage detection circuit, 27...battery temperature detection circuit, 28...battery temperature detection terminal (temperature terminal), 30...inverter circuit (drive unit), 31...motor (brushless motor), 32...stator, 33...rotor, 34...stator winding.

Claims

1. A motor; an operation unit that is operated by an operator to instruct starting and stopping of the motor; a drive unit that drives the motor in response to an operation of the operation unit; a control unit that controls the drive unit; a housing to which a battery pack serving as a driving source for the motor can be detachably attached; A work machine equipped with the control unit is configured to control the drive unit so that a braking force applied to the motor is different between a first state in which the operation unit is operated and then the operation of the operation unit is released, and a second state in which the battery pack is detached from the housing while the motor is rotating. An electrical device characterized by:

2. The work machine according to claim 1, a temperature detection terminal for detecting the temperature of the battery pack; the control unit detects that the battery pack has been removed from the housing based on information input from the temperature detection terminal. A work machine characterized by:

3. A work machine as described in claim 1, a temperature detection terminal for detecting the temperature of the battery pack; the control unit is configured to brake the motor when the voltage input from the temperature detection terminal becomes zero while the operation unit is operated and the motor is rotating. A work machine characterized by:

4. The work machine according to claim 1, a voltage detection unit that detects a voltage on the input side of the drive unit, the control unit detects that the battery pack has been removed from the housing based on an increase in the voltage detected by the voltage detection unit. A work machine characterized by:

5. A work machine as described in claim 1, a voltage detection unit that detects a voltage on the input side of the drive unit, the control unit is configured to brake the motor when the voltage detected by the voltage detection unit increases. A work machine characterized by:

6. A work machine as described in claim 5, the control unit is configured to brake the motor when the voltage is greater than a voltage of the power supply. A work machine characterized by:

7. The work machine according to claim 1, a switch that is provided in a current path between the battery pack and the drive unit and that is switched on and off by operation of the operation unit; a diode connected in parallel with the switch; The diode is connected in a direction that allows current to flow from the drive unit side to the battery pack side. A work machine characterized by:

8. A work machine as described in claim 1, the drive unit has a plurality of switching elements, The braking force varies depending on the number of switching elements that are turned on among the plurality of switching elements. A work machine characterized by:

9. a motor driven by power supplied from a power supply; an operation unit that is operated by an operator to instruct starting and stopping of the motor; a driving unit having a switching element and driving the motor in response to an operation of the operating unit; a voltage detection unit that detects a voltage on the input side of the drive unit; a control unit that controls the drive unit; A work machine equipped with the control unit is configured to brake the motor when the voltage detected by the voltage detection unit increases. A work machine characterized by:

10. The work machine according to claim 9, The control unit is configured to detect a power supply interruption based on an increase in the voltage. A work machine characterized by:

11. The work machine according to claim 9 or 10, the control unit is configured to brake the motor when the voltage is greater than a voltage of the power supply. A work machine characterized by:

12. a motor driven by power supplied from a power supply; an operation unit that is operated by an operator to instruct starting and stopping of the motor; a driving unit having a switching element and driving the motor in response to an operation of the operating unit; a temperature terminal to which temperature information of the power supply is input; a control unit that controls the drive unit; A work machine equipped with The control unit is configured to detect a power interruption based on information input from the temperature terminal. A work machine characterized by:

13. A work machine as described in claim 12, the control unit is configured to brake the motor when the voltage input from the temperature terminal becomes zero while the operation unit is operated and the motor is rotating. A work machine characterized by:

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