Electric tool

Abstract

The objective of the present disclosure is to provide an electric tool capable of quickly stopping driving of a motor after completion of work. This electric tool (100) comprises a motor (1), a holding unit (21), a transmission mechanism (3), a detection unit (4), a determination unit (51), and a control unit (52). The motor (1) rotates in response to a voltage being applied from a battery pack (B1). The holding unit (21) holds a tip tool (X1). The transmission mechanism (3) transmits the rotation of the motor (1) to the tip tool (X1). The detection unit (4) detects the amount of voltage drop in a prescribed period. The determination unit (51) determines whether or not the amount of voltage drop is greater than a threshold value. The control unit (52) stops the motor (1) when the determination unit (51) determines that the amount of voltage drop is greater than the threshold value.

Description

power tools

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to power tools, and more particularly to power tools having a motor.

[0002] Patent Document 1 discloses a power tool including a motor, a connection means for connecting to a battery pack, a voltage detection means, and a control means. The voltage detection means detects the voltage value of the battery pack connected to the connection means. The control means, based on a change in the voltage value of the secondary battery after operating the motor, restricts the operation of the motor when the change in the voltage value is large more than when the change in the voltage value is small.

[0003] Incidentally, in a power tool that uses the output of a motor to perform a task, it is required to quickly stop the driving of the motor after the task is completed.

[0004] JP 2015-104278 A

[0005] An object of the present disclosure is to provide a power tool that can quickly stop the drive of the motor after work is completed.

[0006] A power tool according to one aspect of the present disclosure includes a motor, a holding unit, a transmission mechanism, a detection unit, a determination unit, and a control unit. The motor rotates when voltage is applied from a battery pack. The holding unit holds a tool bit. The transmission mechanism transmits the rotation of the motor to the tool bit. The detection unit detects the amount of voltage drop over a predetermined period. The determination unit determines whether the amount of voltage drop is greater than a threshold. The control unit stops the motor when the determination unit determines that the amount of voltage drop is greater than the threshold.

[0007] FIG. 1 is a block diagram showing a schematic configuration of a power tool according to the present embodiment. FIG. 2 is a graph showing the time change in the voltage applied from the battery pack and the time change in the current flowing from the battery pack to the motor in the power tool. FIG. 3 is a graph different from FIG. 2 showing the time change in the voltage applied from the battery pack in the power tool. FIG. 4 is a side view of a main part of the power tool before a crimping operation is performed on an attachment attached to the power tool. FIG. 5 is a side view of a main part of the power tool after a crimping operation is performed on an attachment attached to the power tool. FIG. 6 is a graph showing the time change in the voltage applied from the battery pack and the time change in the current flowing from the battery pack to the motor in a power tool of a comparative example. FIG. 7 is a graph showing the time change in the voltage applied from the battery pack and the time change in the current flowing from the battery pack to the motor in a power tool of a comparative example when the applied voltage of the battery pack is lower than a predetermined voltage value or the temperature of the battery pack is lower than a predetermined temperature. 8 and 9 are flowcharts showing a rotation speed setting method for setting the rotation speed of the rotary shaft of the motor in the power tool, respectively, and a control method for controlling the driving of the motor in the power tool.

[0008] The embodiments and modifications described below are merely examples of the present disclosure. The present disclosure is not limited to the embodiments and modifications, and various modifications other than these embodiments and modifications are possible depending on the design, etc., as long as they do not deviate from the technical concept of the present disclosure. The drawings described in the following embodiments and modifications are schematic drawings, and the ratios of the sizes and thicknesses of the components in the drawings do not necessarily reflect the actual dimensional ratios.

[0009] (Embodiment) (1) Overview An overview of a power tool 100 according to this embodiment will be described below with reference to FIGS. 1 to 3. FIG.

[0010] 1, the power tool 100 according to this embodiment includes a motor 1, a holding unit 21, a transmission mechanism 3, a detection unit 4, a determination unit 51, and a motor control unit 52. The motor control unit 52 corresponds to the control unit of the present disclosure. The power tool 100 according to this embodiment is operated by application of voltage from a battery pack B1, and is used for work (such as crimping work) that uses the output of the motor 1.

[0011] The motor 1 rotates when voltage is applied from the battery pack B1. The holding unit 21 holds the tool bit X1 that performs work. The transmission mechanism 3 transmits the rotation of the motor 1 to the tool bit X1. The detection unit 4 detects the amount of voltage drop ΔV (see FIGS. 2 and 3) applied from the battery pack B1 over a predetermined period ΔT (see FIGS. 2 and 3). Graph G1 shown in FIGS. 2 and 3 indicates the change over time in the value of the voltage applied from the battery pack B1, i.e., the change over time in the value of the battery voltage of the battery pack B1. In other words, the "amount of voltage drop ΔV" in this disclosure is a value indicating how much the value of the voltage applied from the battery pack B1 (graph G1) has dropped over the predetermined period ΔT.

[0012] The determination unit 51 determines whether the voltage drop ΔV detected by the detection unit 4 is greater than a threshold value. The motor control unit 52 stops (driving) the motor 1 when the determination unit 51 determines that the voltage drop ΔV is greater than the threshold value.

[0013] 2 and 3 , it has been empirically determined that, after time T1 when work is completed, the value of the current flowing from the battery pack B1 to the motor 1 (graph G2) gradually increases and the value of the voltage applied from the battery pack B1 (graph G1) gradually decreases due to factors such as an increase in the load on the tool bit X1. Therefore, in the power tool 100 of this embodiment, when the determination unit 51 determines that the voltage drop ΔV is greater than the threshold, the motor control unit 52 stops (driving) the motor 1, thereby reducing the difference between time T1 when work is completed and time T2 when the motor 1 is stopped. In other words, the power tool 100 of this embodiment has the advantage of being able to quickly stop driving the motor 1 after work is completed.

[0014] (2) Detailed Configuration (2-1) Power Tool Hereinafter, the detailed configuration of the power tool 100 of this embodiment will be described with reference to FIGS. 1 to 7. FIG.

[0015] As shown in Figure 1, the power tool 100 of this embodiment includes a motor 1, an output shaft 2, a transmission mechanism 3, a detection unit 4, a control unit 5, a reduction mechanism 91, a notification unit 92, and an operation unit 93.

[0016] The power tool 100 of this embodiment is used for crimping work using the output of the motor 1 when the attachment A1, which is the tool tip X1, is attached. That is, the output of the motor 1 transmitted to the attachment A1, which is the tool tip X1, is used for the crimping work. In the present disclosure, the "crimping work" refers to, for example, the work of crimping a work object W1 (FIGS. 4 and 5), which is a crimp terminal, a sleeve, or the like, onto an electric wire.

[0017] (Motor) The motor 1 performs a rotational operation (i.e., rotates). More specifically, the motor 1 is driven by application of a voltage from the battery pack B1, and performs a rotational operation.

[0018] The motor 1 is, for example, a brushless motor. In particular, the motor 1 of this embodiment is a synchronous motor, more specifically, a permanent magnet synchronous motor (PMSM). The motor 1 includes a rotor having a rotating shaft 11 (see FIG. 1 ) and a permanent magnet, and a stator having armature windings for three phases (U phase, V phase, and W phase).

[0019] The rotation speed and torque of the rotating shaft 11 of the motor 1 change according to the control by the motor control unit 52. The motor control unit 52 controls the rotation speed and torque of the rotating shaft 11 of the motor 1 by controlling the motor current flowing through the motor 1 in response to the application of voltage from the battery pack B1. In other words, the motor 1 is controlled by the motor control unit 52 so that the rotation speed of the rotating shaft 11 of the motor 1 becomes the rotation speed set by a setting unit 55, which will be described later.

[0020] (Output Shaft) The output shaft 2 is mechanically connected to the rotating shaft 11 of the motor 1 via a reduction gear mechanism 91 and a transmission mechanism 3. The reduction gear mechanism 91 converts the rotation speed and torque of the rotating shaft 11 of the motor 1 into the rotation speed and torque required for the operation (in this embodiment, the crimping operation). The transmission mechanism 3 transmits the rotation speed and torque of the rotating shaft 11 of the motor 1 converted by the reduction gear mechanism 91 to the output shaft 2. That is, the torque of the rotating shaft 11 of the motor 1 is transmitted to the output shaft 2 via the reduction gear mechanism 91 and the transmission mechanism 3. As a result, the output shaft 2 rotates due to the output of the motor 1 output via the reduction gear mechanism 91 and the transmission mechanism 3. The output shaft 2 is a so-called spindle.

[0021] The output shaft 2 is provided with a holding portion 21. The holding portion 21 holds the tool bit X1. The holding portion 21 of this embodiment holds the attachment A1, which is the tool bit X1. That is, the holding portion 21 of this embodiment is configured so that the attachment A1, which is the tool bit X1, can be detachably attached (mounted). In short, the holding portion 21 of this embodiment is a mounting portion to which the attachment A1 can be detachably mounted.

[0022] The transmission mechanism 3 of this embodiment transmits the rotation of the rotary shaft 11 of the motor 1 to the output shaft 2 provided with the holder 21. That is, when the attachment A1, which is the tool bit X1, is attached to the holder 21, the transmission mechanism 3 of this embodiment transmits the rotation of the rotary shaft 11 of the motor 1 to the tool bit X1.

[0023] (Detection Unit) The detection unit 4 detects the amount of voltage drop ΔV applied from the battery pack B1 during a predetermined period ΔT. More specifically, the detection unit 4 measures the value of the voltage applied from the battery pack B1. After the predetermined period ΔT has elapsed, the detection unit 4 detects the difference between the value of the voltage measured at the start of the predetermined period ΔT and the value of the voltage measured at the end of the predetermined period ΔT as the amount of voltage drop ΔV. As an example, the detection unit 4 of this embodiment is a voltage measuring device that measures the value of the voltage applied from the battery pack B1.

[0024] The detection unit 4 detects the amount of voltage drop ΔV during each of a plurality of predetermined periods ΔT (see FIG. 3 ). Although three predetermined periods ΔT1, ΔT2, and ΔT3 are shown in FIG. 3 as an example, in reality, the detection unit 4 detects the amount of voltage drop ΔV during each of a plurality of predetermined periods ΔT that constitute the period from the start of the crimping operation to the stop of driving of the motor 1. In other words, the detection unit 4 continuously detects the amount of voltage drop ΔV during the predetermined period ΔT during the period from the start of the crimping operation to the stop of driving of the motor 1.

[0025] (Controller) As shown in FIG. 1 , the controller 5 includes a determiner 51 , a motor controller 52 , a type acquirer 53 , a temperature acquirer 54 , and a setting unit 55 .

[0026] The determination unit 51 determines whether the voltage drop ΔV (see FIGS. 2 and 3 ) detected by the detection unit 4 is greater than a threshold value. The threshold value here is a preset value. As an example, the threshold value is preset based on an empirically estimated value of the amount of gradual decrease in the voltage applied from the battery pack B1 after time T1 (see FIGS. 2 and 3 ) when the crimping operation is completed.

[0027] The determination unit 51 of this embodiment determines whether the voltage drop ΔV is greater than the threshold value when the mask release condition is satisfied and a predetermined time has elapsed since the determination unit 51 last determined whether the voltage drop ΔV is greater than the threshold value. The mask release condition of this embodiment is to satisfy at least one of the following: a preset mask time has elapsed since the start of the crimping operation; and the value of the current flowing from the battery pack B1 to the motor 1 is equal to or greater than a preset mask release value.

[0028] In this embodiment, when the mask release condition is satisfied and a predetermined time has elapsed since the determination unit 51 last determined whether the voltage drop ΔV is greater than a threshold, the determination unit 51 determines whether the voltage drop ΔV (see FIG. 3) in each of the plurality of predetermined periods ΔT detected by the detection unit 4 is greater than a threshold. For example, the determination unit 51 in this embodiment determines that the voltage drop ΔV1 and ΔV2 (see FIG. 3) in each of the predetermined periods ΔT1 and ΔT2 are equal to or less than the threshold. On the other hand, the determination unit 51 in this embodiment determines that the voltage drop ΔV3 (see FIG. 3) in the predetermined period ΔT3 is greater than the threshold.

[0029] The motor control unit 52 controls the drive (rotational operation) of the motor 1. More specifically, the motor control unit 52 controls the rotation speed and torque of the rotating shaft 11 of the motor 1 by controlling the motor current flowing through the motor 1 when a voltage is applied from the battery pack B1. The motor control unit 52 controls the motor current so that the rotation speed of the rotating shaft 11 of the motor 1 becomes the rotation speed set by the setting unit 55.

[0030] When the operation unit 93 accepts an operation to start the crimping operation and the setting unit 55 sets the rotation speed of the motor 1, the motor control unit 52 starts driving the motor 1 (i.e., controls the motor 1 to start rotating). More specifically, when the operation unit 93 accepts an operation to start the crimping operation and the setting unit 55 sets the rotation speed of the motor 1, the motor control unit 52 controls the application of voltage from the battery pack B1 to the motor 1 and the flow of motor current to the motor 1.

[0031] When the determination unit 51 determines that the amount of voltage drop ΔV is greater than the threshold value, the motor control unit 52 stops driving the motor 1 (i.e., controls the motor 1 to stop rotating). More specifically, when the determination unit 51 determines that the amount of voltage drop ΔV is greater than the threshold value, the motor control unit 52 controls the motor 1 so that no voltage is applied from the battery pack B1 to the motor 1 and no motor current flows through the motor 1. The motor control unit 52 also stops the rotation of the motor 1 when the operation unit 93 accepts an operation to end the crimping operation.

[0032] The type acquisition unit 53 acquires type information, which is information about the type of battery pack B1 attached to the power tool 100. More specifically, the type information, which is information about the type of battery pack B1 attached to the power tool 100, is stored in a memory unit B13 (see FIG. 1 ), which will be described later, of the battery pack B1. The type acquisition unit 53 acquires the type information from the memory unit B13. For example, when the battery pack B1 is attached to the power tool 100, the type acquisition unit 53 acquires the type information from the memory unit B13 of the attached battery pack B1.

[0033] In this embodiment, the type information acquired by the type acquisition unit 53 includes an applied voltage value, which is the value of the voltage that the battery pack B1 attached to the power tool 100 can apply to the motor 1. The "applied voltage value" referred to in this disclosure is, for example, the upper limit of the voltage that the battery pack B1 can apply to the motor 1 at room temperature when it is fully charged and not deteriorated. As an example, the type information is information indicating whether the applied voltage value of the battery pack B1 attached to the power tool 100 is 14.4 V or 18.0 V. The type acquisition unit 53 may acquire the type information by measuring the voltage applied to the motor 1 from the battery pack B1 attached to the power tool 100.

[0034] That is, the type obtaining unit 53 obtains type information relating to the applied voltage value of the battery pack B1 attached to the power tool 100. As an example, the type obtaining unit 53 obtains whether the applied voltage value of the battery pack B1 attached to the power tool 100 is 14.4 V or 18.0 V.

[0035] The temperature acquisition unit 54 acquires temperature information related to the temperature of the battery pack B1 attached to the power tool 100. More specifically, a temperature measurement unit B12 (see FIG. 1 ), which will be described later, of the battery pack B1 measures the temperature of the power storage unit B11, and the temperature acquisition unit 54 acquires the temperature of the power storage unit B11 measured by the temperature measurement unit B12 as temperature information. The temperature information related to the temperature of the battery pack B1 may be the temperature of the battery pack B1 itself, or may be signal information obtained by converting the temperature of the battery pack B1 into a voltage value.

[0036] The setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based on the type information acquired by the type acquisition unit 53 and the temperature information acquired by the temperature acquisition unit 54. That is, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based on the applied voltage value of the battery pack B1 acquired by the type acquisition unit 53 and the temperature of the battery pack B1 acquired by the temperature acquisition unit 54.

[0037] The setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a first rotation speed when the applied voltage value of the battery pack B1 is equal to or greater than a predetermined voltage value and the temperature of the battery pack B1 is equal to or greater than a predetermined temperature. On the other hand, when the applied voltage value of the battery pack B1 is lower than the predetermined voltage value or the temperature of the battery pack B1 is lower than the predetermined temperature, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a second rotation speed lower than the first rotation speed. As an example, the first rotation speed is 16,460 rpm and the second rotation speed is 6,580 rpm. The predetermined voltage value is, for example, 18.0 V. The predetermined temperature is, for example, 10°C.

[0038] The control unit 5 preferably includes a computer system. In a computer system, a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) reads and executes programs stored in memory to realize some or all of the functions of the control unit 5. The computer system's main hardware configuration is a processor that operates according to a program. The type of processor is not important as long as it can realize functions by executing a program. The processor may be composed of one or more electronic circuits, including a semiconductor integrated circuit (IC) or an LSI (Large Scale Integration). While ICs and LSIs are used here, the names may vary depending on the degree of integration, and may be called system LSIs, VLSIs (Very Large Scale Integration), or ULSIs (Ultra Large Scale Integration). Field-programmable gate arrays (FPGAs), which are programmed after the LSI is manufactured, or reconfigurable logic devices that can reconfigure the connections within the LSI or set up circuit partitions within the LSI, can also be used for the same purpose. Multiple electronic circuits may be integrated on a single chip or on multiple chips. The plurality of chips may be integrated into one device, or may be provided in a plurality of devices.

[0039] (Notification unit) The notification unit 92 notifies the operator of the crimping work of how the setting unit 55 set the rotation speed of the rotating shaft 11 of the motor 1. The notification unit 92 of the present embodiment notifies the operator of the crimping work that the setting unit 55 has set the rotation speed of the rotating shaft 11 of the motor 1 to the second rotation speed.

[0040] The notification unit 92 of this embodiment is a light-emitting unit that has a light-emitting element (such as an LED element) and emits (turns on) light. The notification unit 92 of this embodiment emits light when the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to the second rotation speed, thereby notifying the operator of the crimping work.

[0041] (Operation Unit) The operation unit 93 accepts operations for controlling the rotation of the rotary shaft 11 of the motor 1. That is, the operation unit 93 accepts operations for starting or ending the crimping operation performed using the output of the motor 1. By pulling the operation unit 93, the motor 1 can be switched on and off.

[0042] (2-2) Attachment The tool bit X1 of this embodiment is an attachment A1 that is detachably attached to the holding portion 21 of the power tool 100. As shown in Figures 1, 4, and 5, the tool bit X1, or the attachment A1, includes an engaging portion A11, a drive mechanism A12, a female die A13, and a male die A14. In the attachment A1, a work object W1 (Figures 4 and 5), such as a crimp terminal or a sleeve, and an electric wire (not shown) are inserted between the female die A13 and the male die A14. When the male die A14 is driven toward the female die A13, the female die A13 and the male die A14 crimp the work object W1 to the electric wire.

[0043] The engaging portion A11 engages with the holding portion 21 of the power tool 100. In this embodiment, the engaging portion A11 engages with the holding portion 21 provided on the output shaft 2 of the power tool 100.

[0044] The drive mechanism A12 drives the male die A14 toward the female die A13 using the transmitted output (rotation) of the rotary shaft 11 of the motor 1. When the engagement portion A11 is engaged with the holding portion 21, the drive mechanism A12 transmits the rotation of the output shaft 2, i.e., the rotation of the rotary shaft 11 of the motor 1. The drive mechanism A12 drives the male die A14 from a state in which the work object W1 and the electric wire are inserted between the female die A13 and the male die A14 (see FIG. 4) to a state in which the female die A13 and the male die A14 crimp the work object W1 to the electric wire (see FIG. 5). That is, in this embodiment, the output (rotation) of the rotary shaft 11 of the motor 1 transmitted to the attachment A1, which is the tip tool X1, is used for the crimping operation.

[0045] It has been empirically found that after the male die A14 is driven toward the female die A13 and the work object W1 is crimped to the electric wire (i.e., after the crimping operation is completed), factors such as an increase in the load on the male die A14 cause the value of the current flowing from the battery pack B1 to the motor 1 (graph G2) to increase gradually, and the value of the voltage applied from the battery pack B1 (graph G1) to decrease gradually, as shown in Figures 2 and 3.

[0046] (2-3) Battery Pack The battery pack B1 is a rechargeable power supply unit that is detachably attached to the power tool 100. In this embodiment, the battery pack B1 is not a component of the power tool 100. However, the power tool 100 may include the battery pack B1 as a component.

[0047] As shown in FIG. 1, the battery pack B1 includes a power storage unit B11, a temperature measurement unit B12, and a storage unit B13.

[0048] The power storage unit B11 is a chargeable and dischargeable secondary battery. The temperature measurement unit B12 measures the temperature of the power storage unit B11. The temperature measurement unit B12 outputs the measurement result to the temperature acquisition unit 54 of the power tool 100. The temperature measurement unit B12 is, for example, a temperature sensor.

[0049] The memory unit B13 stores type information, which is information relating to the type of the battery pack B1 attached to the power tool 100. In this embodiment, the type information stored in the memory unit B13 includes an applied voltage value, which is the value of the voltage that the battery pack B1 can apply to the motor 1 of the power tool 100. The memory unit B13 is, for example, a storage device such as a magnetic core memory or a semiconductor memory. The memory unit B13 may also be an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD).

[0050] (3) Comparison: Graph Ge1 in Fig. 6 shows the change over time in the value of the voltage applied from the battery pack in the power tool of the comparative example, while graph Ge2 in Fig. 6 shows the change over time in the value of the current flowing from the battery pack to the motor in the power tool of the comparative example.

[0051] As shown in Figure 6, it has been empirically found that in the power tool of the comparative example, after time Te1 when the crimping operation is completed, the value of the current flowing from the battery pack to the motor (graph Ge2) gradually increases and the value of the voltage applied from the battery pack B1 (graph Ge1) gradually decreases due to factors such as an increase in the load on the tool bit. Therefore, in the power tool of the comparative example, the motor control unit stops driving the motor when the value of the current flowing from the battery pack to the motor (graph Ge2) exceeds a predetermined stop current value Ath or when the value of the voltage applied from the battery pack (graph Ge1) falls below a predetermined stop voltage value Vth. Note that Figure 6 illustrates a case in which the value of the voltage applied from the battery pack (graph Ge1) falls below the stop voltage value Vth before the value of the current flowing from the battery pack to the motor (graph Ge2) exceeds the stop current value Ath. As a result, in the power tool of the comparative example, the difference between time Te1 when the crimping operation is completed and time Te2 when the motor stops driving may be large.

[0052] 2 and 3 show the change over time in the value of the voltage applied from the battery pack B1 in the power tool 100 of this embodiment. On the other hand, graph G2 in Fig. 2 shows the change over time in the value of the current flowing from the battery pack B1 to the motor 1 in the power tool 100 of this embodiment.

[0053] In the power tool 100 of this embodiment, the motor control unit 52 stops the operation of the motor 1 when the determination unit 51 determines that the voltage drop ΔV is greater than the threshold value. Therefore, the time T2 at which the motor control unit 52 stops the operation of the motor 1 is closer to the time T1 at which the work is completed than the time at which the value of the current flowing from the battery pack B1 to the motor 1 (graph G2) is expected to exceed the stop current value Ath or the time at which the value of the voltage applied from the battery pack B1 (graph G1) is expected to fall below the stop voltage value Vth. In other words, the power tool 100 of this embodiment has the advantage of being able to make the difference between the time T1 at which the work is completed and the time T2 at which the operation of the motor 1 is stopped smaller than the power tool of the comparative example.

[0054] 7 shows the change over time in the value of the voltage applied from the battery pack when the applied voltage value of the battery pack is lower than a predetermined voltage value or the temperature of the battery pack is lower than a predetermined temperature in the power tool of the comparative example. On the other hand, graph Ge4 shown in FIG. 7 shows the change over time in the value of the current flowing from the battery pack to the motor when the applied voltage value of the battery pack is lower than a predetermined voltage value or the temperature of the battery pack is lower than a predetermined temperature in the power tool of the comparative example.

[0055] As shown in Fig. 7 , in the power tool of the comparative example, when the applied voltage value of the battery pack is lower than a predetermined voltage value or the temperature of the battery pack is lower than a predetermined temperature, it is conceivable that the value of the current flowing from the battery pack to the motor (graph Ge4) exceeds a preset stop current value Ath or the value of the voltage applied from the battery pack (graph Ge3) falls below a preset stop voltage value Vth at time Te3, which is before the end of the crimping operation. In the power tool of the comparative example, in the above cases, the operation of the motor is stopped at time Te3, which is before the end of the operation. Note that Fig. 7 illustrates a case in which the value of the voltage applied from the battery pack (graph Ge3) falls below the stop voltage value Vth at time Te3, which is before the end of the operation.

[0056] On the other hand, in the power tool 100 of this embodiment, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based on the applied voltage value of the battery pack B1 acquired by the type acquisition unit 53 and the temperature of the battery pack B1 acquired by the temperature acquisition unit 54. Therefore, when the applied voltage value of the battery pack B1 is lower than a predetermined voltage value or the temperature of the battery pack B1 is lower than a predetermined temperature, the power tool 100 of this embodiment has the advantage of being able to prevent the value of the current flowing from the battery pack B1 to the motor 1 from exceeding the stop current value Ath or the value of the voltage applied from the battery pack B1 from falling below the stop voltage value Vth before the crimping operation is completed, regardless of the type and temperature of the battery pack B1.

[0057] (4) Operation (4-1) Method for Setting the Rotational Speed ​​First, a method for setting the rotational speed of the rotary shaft 11 of the motor 1 in the power tool 100 will be described with reference to FIG.

[0058] As shown in FIG. 8, the rotation speed setting method includes a type acquisition step ST11, a first determination step ST12, a temperature acquisition step ST13, a second determination step ST14, a third determination step ST15, a setting step ST16, a notification step ST17, and a driving step ST18.

[0059] In the type acquisition step ST11, the type acquisition unit 53 acquires type information, which is information relating to the type of the battery pack B1 attached to the power tool 100. More specifically, in the type acquisition step ST11, the type acquisition unit 53 acquires type information stored in the memory unit B13 of the battery pack B1 attached to the power tool 100. In the type acquisition step ST11 of this embodiment, the type acquisition unit 53 acquires type information relating to the applied voltage value of the battery pack B1 attached to the power tool 100. As an example, when the battery pack B1 is attached to the power tool 100, the type acquisition unit 53 performs the type acquisition step ST11.

[0060] In the first determination step ST12, the motor control unit 52 determines whether the operation unit 93 has received an operation to start the crimping operation. If the motor control unit 52 determines that the operation unit 93 has not received an operation to start the crimping operation (ST12: No), the motor control unit 52 continues the first determination step ST12. On the other hand, if the motor control unit 52 determines that the operation unit 93 has received an operation to start the crimping operation (ST12: Yes), the temperature acquisition unit 54 performs a temperature acquisition step ST13 to acquire temperature information, which is information related to the temperature of the battery pack B1 attached to the power tool 100. More specifically, in the temperature acquisition step ST13, the temperature acquisition unit 54 acquires the temperature of the power storage unit B11 measured by the temperature measurement unit B12 as the temperature information.

[0061] In the second determination step ST14, the setting unit 55 determines whether the voltage value applied to the battery pack B1 is equal to or greater than a predetermined voltage value. In the third determination step ST15, the setting unit 55 determines whether the temperature of the battery pack B1 is equal to or greater than a predetermined temperature. In the rotation speed setting method of this embodiment, after determining in the second determination step ST14 that the voltage value applied to the battery pack B1 is equal to or greater than the predetermined voltage value (ST14: Yes), the setting unit 55 performs the third determination step ST15.

[0062] In the setting step ST16, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1. More specifically, in the setting step ST16, if it is determined that the applied voltage value of the battery pack B1 is equal to or greater than a predetermined voltage value (ST14: Yes) and if it is determined that the temperature of the battery pack B1 is equal to or greater than a predetermined temperature (ST15: Yes), the setting unit 55 performs a first setting step ST161 in which the rotation speed of the rotating shaft 11 of the motor 1 is set to a first rotation speed. On the other hand, in the setting step ST16, if it is determined that the applied voltage value of the battery pack B1 is smaller than the predetermined voltage value (ST14: No) or if it is determined that the temperature of the battery pack B1 is smaller than the predetermined temperature (ST15: No), the setting unit 55 performs a second setting step ST162 in which the rotation speed of the rotating shaft 11 of the motor 1 is set to a second rotation speed.

[0063] In notification step ST17, the notification unit 92 notifies the operator of the crimping operation of how the setting unit 55 set the rotation speed of the rotating shaft 11 of the motor 1. In the rotation speed setting method of the present embodiment, after the setting unit 55 performs the second setting step ST162, the notification unit 92 performs notification step ST17 of notifying the operator that the setting unit 55 has set the rotation speed of the rotating shaft 11 of the motor 1 to the second rotation speed. More specifically, in notification step ST17, the notification unit 92 emits light to notify the operator of the crimping operation that the setting unit 55 has set the rotation speed of the rotating shaft 11 of the motor 1 to the second rotation speed.

[0064] In the driving step ST18, the motor control unit 52 drives the motor 1 so that the rotation speed of the motor 1 becomes the rotation speed set by the setting unit 55 in the setting step ST16 (i.e., controls the motor 1 so that the driving of the motor 1 starts).

[0065] 8 is merely an example of the method for setting the rotation speed in the power tool 100 of this embodiment, and the order of the steps may be changed as appropriate, or any of the steps may be omitted as appropriate. For example, the order of the second determination step ST14 and the third determination step ST15 may be changed as appropriate.

[0066] (4-2) Control Method Next, a control method for controlling the drive (rotational operation) of the motor 1 in the power tool 100 will be described with reference to FIG.

[0067] As shown in FIG. 9, the control method includes a voltage measurement step ST21, a first determination step ST22, a detection step ST23, a second determination step ST24, a third determination step ST25, a fourth determination step ST26, and a control step ST27.

[0068] In the voltage measurement step ST21, the detection unit 4 measures the value of the voltage applied from the battery pack B1. In the first determination step ST22, the detection unit 4 determines whether a predetermined period ΔT has elapsed since the detection unit 4 measured the value of the voltage applied from the battery pack B1 in the voltage measurement step ST21. If the detection unit 4 determines that the predetermined period ΔT has not elapsed (ST22: No), the detection unit 4 continues the first determination step ST22. If the detection unit 4 determines that the predetermined period ΔT has elapsed (ST22: Yes), the detection unit 4 performs the detection step ST23. In the detection step ST23, the detection unit 4 measures the value of the voltage applied from the battery pack B1 again to detect the amount of drop ΔV of the voltage applied from the battery pack B1 during the predetermined period ΔT.

[0069] In the second determination step ST24, the determination unit 51 determines whether or not a mask release condition is satisfied. The mask release condition in this embodiment is that at least one of the following conditions is satisfied: a predetermined mask time has elapsed since the start of the crimping operation, and the value of the current flowing from the battery pack B1 to the motor 1 is equal to or greater than a predetermined mask release value. That is, in the second determination step ST24 in this embodiment, the determination unit 51 determines whether or not at least one of the following conditions is satisfied: a predetermined mask time has elapsed since the start of the crimping operation, and the value of the current flowing from the battery pack B1 to the motor 1 is equal to or greater than a predetermined mask release value.

[0070] In the third determination step ST25, the determination unit 51 determines whether a predetermined time has elapsed since the previous determination of whether the voltage drop ΔV is greater than the threshold value. In the control method of this embodiment, the determination unit 51 performs the third determination step ST25 after determining in the second determination step ST24 that the mask release condition is satisfied (ST24: Yes).

[0071] If the determination unit 51 determines that the mask release condition is not satisfied (ST24: No), or if the determination unit 51 determines that a predetermined time has not elapsed since the previous determination of whether the voltage drop ΔV is greater than the threshold value (ST25: No), the detection unit 4 performs the voltage measurement step ST21. On the other hand, if the determination unit 51 determines that the mask release condition is satisfied (ST24: Yes) and if the determination unit 51 determines that a predetermined time has elapsed since the previous determination of whether the voltage drop ΔV is greater than the threshold value (ST25: Yes), the determination unit 51 performs the fourth determination step ST26. In the fourth determination step ST26, the determination unit 51 determines whether the voltage drop ΔV detected in the current detection step ST23 is greater than the threshold value.

[0072] If the determination unit 51 determines that the voltage drop ΔV is not greater than the threshold, i.e., that the voltage drop ΔV is equal to or less than the threshold (ST26: No), the detection unit 4 performs the voltage measurement step ST21. On the other hand, if the determination unit 51 determines that the voltage drop ΔV is greater than the threshold (ST26: Yes), the motor control unit 52 performs the control step ST27 to stop the driving of the motor 1 (i.e., to control the motor 1 to stop its rotation). More specifically, in the control step ST27, the motor control unit 52 controls the motor 1 so that no voltage is applied from the battery pack B1 to the motor 1 and no motor current flows through the motor 1.

[0073] 9 is merely an example of a control method for the power tool 100 of this embodiment, and the order of the steps may be changed as appropriate, or any of the steps may be omitted as appropriate. For example, the order of the second determination step ST24 and the third determination step ST25 may be changed as appropriate.

[0074] (5) Advantages The power tool 100 of this embodiment includes a motor 1, a holding unit 21, a transmission mechanism 3, a detection unit 4, a determination unit 51, and a motor control unit 52. The motor 1 rotates when voltage is applied from the battery pack B1. The holding unit 21 holds the tool bit X1 that performs work. The transmission mechanism 3 transmits the rotation of the motor 1 to the tool bit X1. The detection unit 4 detects a voltage drop ΔV (see FIGS. 2 and 3 ) applied from the battery pack B1 during a predetermined period ΔT. The determination unit 51 determines whether the voltage drop ΔV detected by the detection unit 4 is greater than a threshold value. The motor control unit 52 stops driving the motor 1 when the determination unit 51 determines that the voltage drop ΔV is greater than the threshold value.

[0075] As a result, the power tool 100 of this embodiment can reduce the difference between the time T1 when the work is completed and the time T2 when the driving of the motor 1 is stopped. In other words, the power tool 100 of this embodiment has the advantage of being able to quickly stop the driving of the motor 1 after the work is completed.

[0076] The power tool 100 of this embodiment further includes a type acquisition unit 53 and a setting unit 55. The type acquisition unit 53 acquires type information, which is information about the type of the battery pack B1 attached to the power tool 100. The setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based on the type information acquired by the type acquisition unit 53.

[0077] In the power tool of the comparative example, depending on the type of battery pack attached to the power tool, it is possible that the voltage applied from the battery pack may fall below the stop voltage value Vth before the work is completed. In the power tool of the comparative example, in the above case, the motor is stopped before the work is completed. On the other hand, in the power tool 100 of the present embodiment, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based on the type of battery pack B1 acquired by the type acquisition unit 53, thereby achieving the effect of preventing the voltage applied from the battery pack B1 from falling below the stop voltage value Vth. As a result, the power tool 100 of the present embodiment has the advantage of preventing the motor 1 from being stopped before the work is completed, regardless of the type of battery pack B1 attached to the power tool 100.

[0078] In the power tool 100 of this embodiment, the type information acquired by the type acquisition unit 53 includes an applied voltage value, which is the value of the voltage that the battery pack B1 attached to the power tool 100 can apply to the motor 1.

[0079] In the power tool of the comparative example, depending on the voltage that the battery pack can apply to the motor, it is possible that the voltage applied from the battery pack will fall below the stop voltage Vth before the work is completed. In the power tool of the comparative example, in the above case, the motor is stopped before the work is completed. On the other hand, in the power tool 100 of the present embodiment, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based on the voltage that the battery pack B1 can apply to the motor 1, thereby preventing the voltage applied from the battery pack B1 from falling below the stop voltage Vth. As a result, the power tool 100 of the present embodiment has the advantage of preventing the motor 1 from being stopped before the work is completed, regardless of the voltage that the battery pack B1 can apply to the motor 1.

[0080] In the power tool 100 of this embodiment, when the voltage applied to the battery pack B1 is equal to or greater than a predetermined voltage value, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a first rotation speed. On the other hand, when the voltage applied to the battery pack B1 is less than the predetermined voltage value, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a second rotation speed that is smaller than the first rotation speed.

[0081] This has the advantage that, regardless of the value of the voltage that the battery pack B1 can apply to the motor 1, it is possible to more effectively prevent the motor 1 from stopping operation before the work is completed.

[0082] The power tool 100 of this embodiment further includes a temperature acquisition unit 54 and a setting unit 55. The temperature acquisition unit 54 acquires temperature information, which is information relating to the temperature of the battery pack B1 attached to the power tool 100. The setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based on the temperature information acquired by the temperature acquisition unit 54.

[0083] In the power tool of the comparative example, depending on the temperature of the battery pack B1 attached to the power tool, it is possible that the voltage applied from the battery pack B1 may fall below the stop voltage value Vth before the work is completed. In the power tool of the comparative example, in the above case, the motor is stopped before the work is completed. On the other hand, in the power tool 100 of the present embodiment, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based on the temperature of the battery pack B1 acquired by the temperature acquisition unit 54, thereby achieving the effect of preventing the voltage applied from the battery pack B1 from falling below the stop voltage value Vth. As a result, the power tool 100 of the present embodiment has the advantage of preventing the motor 1 from being stopped before the work is completed, regardless of the temperature of the battery pack B1 attached to the power tool 100.

[0084] In the power tool 100 of this embodiment, when the temperature of the battery pack B1 is equal to or higher than a predetermined temperature, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a first rotation speed. On the other hand, when the temperature of the battery pack B1 is lower than the predetermined temperature, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a second rotation speed lower than the first rotation speed.

[0085] This has the advantage of more effectively preventing the motor 1 from stopping before the work is completed, regardless of the temperature of the battery pack B1 attached to the power tool 100.

[0086] In the power tool 100 of this embodiment, the output (rotation) of the motor 1 transmitted to the attachment A1, which is the tool tip X1, is used for crimping work.

[0087] As a result, the power tool 100 of this embodiment has the advantage that the driving of the motor 1 can be stopped quickly after the crimping operation is completed.

[0088] (6) Modifications The above-described embodiment is merely one of various embodiments of the present disclosure. The above-described embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. The following modifications may be realized in appropriate combination.

[0089] In the above-described embodiment, the holding portion 21 is configured to allow the attachment A1, which is the tool bit X1, to be detachably attached (mounted). However, the holding portion 21 may be configured integrally with the tool bit X1 to hold the tool bit X1. In other words, the tool bit X1 does not have to be detachably attached to the holding portion 21 of the power tool 100. In other words, the tool bit X1 does not have to be the attachment A1.

[0090] In the above embodiment, the control unit 5 includes both the type acquisition unit 53 and the temperature acquisition unit 54. However, the control unit 5 may include at least one of the type acquisition unit 53 and the temperature acquisition unit 54.

[0091] When the control unit 5 has only the type acquisition unit 53, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based only on the type information acquired by the type acquisition unit 53. Specifically, when the applied voltage value of the battery pack B1 is equal to or greater than a predetermined voltage value, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a first rotation speed. On the other hand, when the applied voltage value of the battery pack B1 is less than the predetermined voltage value, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a second rotation speed that is smaller than the first rotation speed.

[0092] Furthermore, when the control unit 5 has only the temperature acquisition unit 54, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 based only on the temperature information acquired by the temperature acquisition unit 54. Specifically, when the temperature of the battery pack B1 is equal to or higher than a predetermined temperature, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a first rotation speed. On the other hand, when the temperature of the battery pack B1 is lower than the predetermined temperature, the setting unit 55 sets the rotation speed of the rotating shaft 11 of the motor 1 to a second rotation speed lower than the first rotation speed.

[0093] (Summary) A power tool (100) of a first aspect includes a motor (1), a holding unit (21), a transmission mechanism (3), a detection unit (4), a determination unit (51), and a control unit (52). The motor (1) rotates when voltage is applied from a battery pack (B1). The holding unit (21) holds a tool bit (X1). The transmission mechanism (3) transmits the rotation of the motor (1) to the tool bit (X1). The detection unit (4) detects a voltage drop (ΔV) over a predetermined period (ΔT). The determination unit (51) determines whether the voltage drop (ΔV) is greater than a threshold value. The control unit (52) stops the motor (1) when the determination unit (51) determines that the voltage drop (ΔV) is greater than the threshold value.

[0094] This embodiment has the advantage that the driving of the motor (1) can be stopped quickly after the work is completed.

[0095] The power tool (100) of the second aspect is the same as the power tool (100) of the first aspect, but further includes a type acquisition unit (53) and a setting unit (55). The type acquisition unit (53) acquires type information, which is information about the type of the battery pack (B1). The setting unit (55) sets the rotation speed of the motor (1) based on the type information.

[0096] According to this aspect, there is an advantage that the motor (1) can be prevented from stopping before the work is completed, regardless of the type of battery pack (B1) attached to the power tool (100).

[0097] In the power tool (100) of the third aspect, in the second aspect, the type information includes an applied voltage value that is a value of voltage that the battery pack (B1) can apply to the motor (1).

[0098] This embodiment has the advantage that it is possible to prevent the motor (1) from stopping before the work is completed, regardless of the value of the voltage that the battery pack (B1) can apply to the motor (1).

[0099] The power tool (100) of a fourth aspect is the power tool (100) of the third aspect, wherein the setting unit (55) sets the rotation speed to a first rotation speed when the applied voltage value is equal to or greater than a predetermined voltage value, and sets the rotation speed to a second rotation speed lower than the first rotation speed when the applied voltage value is less than the predetermined voltage value.

[0100] This embodiment has the advantage that it is possible to further prevent the motor (1) from stopping before the work is completed, regardless of the value of the voltage that the battery pack (B1) can apply to the motor (1).

[0101] The power tool (100) of a fifth aspect is the power tool (100) of any one of the first to fourth aspects, further including a temperature acquisition unit (54) and a setting unit (55). The temperature acquisition unit (54) acquires temperature information relating to the temperature of the battery pack (B1). The setting unit (55) sets the rotation speed of the motor (1) based on the temperature information.

[0102] This embodiment has the advantage that the motor (1) can be prevented from stopping before the work is completed, regardless of the temperature of the battery pack (B1) attached to the power tool (100).

[0103] The sixth aspect of the power tool (100) is the fifth aspect, wherein the setting unit (55) sets the rotation speed to a first rotation speed when the temperature is equal to or higher than a predetermined temperature, and sets the rotation speed to a second rotation speed lower than the first rotation speed when the temperature is lower than the predetermined temperature.

[0104] This embodiment has the advantage that it is possible to further prevent the motor (1) from stopping before the work is completed, regardless of the temperature of the battery pack (B1) attached to the power tool (100).

[0105] The seventh aspect of the power tool (100) is any one of the first to sixth aspects, wherein the output of the motor (1) transmitted to the tool bit (X1) is used for crimping work.

[0106] This embodiment has the advantage that the driving of the motor (1) can be stopped quickly after the crimping operation is completed.

[0107] REFERENCE SIGNS LIST 100 Power tool 1 Motor 3 Transmission mechanism 4 Detection unit 52 Control unit (motor control unit) 21 Holding unit 51 Determination unit 53 Type acquisition unit 54 Temperature acquisition unit 55 Setting unit B1 Battery pack X1 Tool tip ΔT Predetermined period ΔV Amount of voltage drop

Claims

1. An electric power tool comprising: a motor that rotates when voltage is applied from a battery pack; a holding unit that holds a tool bit; a transmission mechanism that transmits the rotation of the motor to the tool bit; a detection unit that detects the amount of voltage drop over a predetermined period of time; a determination unit that determines whether the amount of voltage drop is greater than a threshold value; and a control unit that stops the motor when the determination unit determines that the amount of voltage drop is greater than the threshold value.

2. The power tool according to claim 1, further comprising: a type acquisition unit that acquires type information that is information relating to the type of the battery pack; and a setting unit that sets the rotation speed of the motor based on the type information.

3. The power tool according to claim 2, wherein the type information includes an applied voltage value that is the value of the voltage that the battery pack can apply to the motor.

4. The power tool according to claim 3, wherein the setting unit sets the rotation speed to a first rotation speed when the applied voltage value is equal to or greater than a predetermined voltage value, and sets the rotation speed to a second rotation speed lower than the first rotation speed when the applied voltage value is smaller than the predetermined voltage value.

5. The power tool according to any one of claims 1 to 4, further comprising: a temperature acquisition unit that acquires temperature information that is information relating to the temperature of the battery pack; and a setting unit that sets the rotation speed of the motor based on the temperature information.

6. The power tool according to claim 5, wherein the setting unit sets the rotation speed to a first rotation speed when the temperature is equal to or higher than a predetermined temperature, and sets the rotation speed to a second rotation speed lower than the first rotation speed when the temperature is lower than the predetermined temperature.

7. The power tool according to any one of claims 1 to 6, wherein the output of the motor transmitted to the tool bit is used for crimping work.

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