Impact driver

Abstract

To provide an electric operating machine configured to control rotation of a motor according to operation amounts of an operation part, wherein, such a control characteristic for the motor can be set that the motor can be driven at the maximum rotation rate even if the operation amounts of the operation part are small.SOLUTION: An electric operating machine comprises: a motor; an operation part; a control part for controlling rotation of the motor according to operation amounts of the operation part; and a setting part that can selectively set, as a control characteristic for the motor through the control part, one of preregistered control characteristics. One of the control characteristics that can be set in the setting part is a specific control characteristic such that: a control range in which the rotation rate of the motor reaches the maximum rotation rate from the minimum rotation rate becomes equal to 50% or less of an effective operation range, within the effective operation range in which the motor can be driven by the operation of the operation part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an electric working machine configured to control the rotation of a motor serving as a power source in accordance with the amount of operation of an operating unit. [Background technology]

[0002] Conventionally, electric work machines such as power tools are known that are provided with a trigger that is pulled by a user as an operating unit for commanding the driving and stopping of a motor, and are configured to control the rotation of the motor according to the amount of operation of the trigger (see, for example, Patent Document 1).

[0003] In this type of electric work machine, the motor rotation speed changes depending on whether the trigger is pulled lightly or strongly, and the motor control characteristics are preset so that the motor rotation speed reaches maximum when the trigger is pulled more than a predetermined amount. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-104969 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned conventional electric operating machine, the control characteristics of the motor are set so that the rotation speed of the motor reaches the maximum rotation speed when the trigger is fully pulled and the pulling amount reaches near the maximum pulling amount.

[0006] This is to allow the user to adjust the motor speed by operating the trigger, but in order to rotate the motor at the maximum speed set in the control characteristics, the user must pull the trigger all the way.

[0007] Therefore, if the work performed by the electric work machine requires the motor to frequently rotate at maximum rotation speed, the user will need to fully pull the trigger frequently, which can cause fatigue in the user's fingers.

[0008] For example, when tightening a bolt using an impact driver with an impact mechanism, the tool bit driven by the motor is fitted into the head of the bolt, so that the tool bit will not come off the bolt even if the motor is rotated at maximum speed immediately after starting the work.

[0009] For this reason, when performing such tightening work, the user must fully pull the trigger immediately after starting the work in order to firmly tighten the bolt with the impact mechanism; however, this causes fatigue in the fingers, making it impossible to continue the work for long periods of time.

[0010] One aspect of the present disclosure is that, in an electric work machine configured to control the rotation of a motor in accordance with the amount of operation of an operating unit, it is desirable to be able to set, as the control characteristic of the motor, a control characteristic that can drive the motor at the maximum rotation speed even when the amount of operation of the operating unit is small. [Means for solving the problem]

[0011] The electric operating machine according to one aspect of the present disclosure includes a motor, an operating unit for instructing driving and stopping of the motor, and a control unit for controlling the motor speed in accordance with an amount of operation of the operating unit so that the greater the amount of operation, the greater the rotation speed of the motor. The motor control unit includes a control section for controlling the motor and a setting section for setting the control characteristics of the motor controlled by the control section.

[0012] The setting unit sets one of a plurality of preregistered control characteristics as the control characteristic of the motor to be controlled by the control unit. One of the plurality of control characteristics that can be set by the setting unit is a specific control characteristic that is set so that the control range, from the minimum rotation speed to the maximum rotation speed of the motor in the control characteristic, is narrower than the other control characteristics and is 50% or less of the effective operation range in which the motor can be driven by the operation of the operation unit.

[0013] Therefore, according to the electric work machine disclosed herein, if a specific control characteristic is set as the control characteristic when the control unit controls the motor, the motor rotation speed will reach its maximum rotation speed with just a slight operation of the operating unit.

[0014] Therefore, when a user performs an operation that rotates the motor at the maximum rotation speed, by setting the specific control characteristic via the setting unit, the user can rotate the motor at the maximum rotation speed without operating the operation unit to near the maximum operation amount, which allows the user to perform the operation for a long period of time without feeling fatigue in the fingers due to operating the operation unit.

[0015] Here, the setting unit may be configured to set the specific control characteristic in a bolt mode in which the motor is rotated with a tool bit driven by the motor fitted onto a bolt or a nut.

[0016] In other words, in the bolt mode, as described above, the motor is rotated at high speed immediately after the start of work, thereby improving work efficiency. Therefore, if a specific control characteristic is set in this bolt mode, the user can rotate the motor at high speed with a slight operation of the operation unit, thereby reducing finger fatigue.

[0017] In this case, the specific control characteristic may include control to stop or reduce the rotation of the motor when the load on the motor decreases while the motor is rotating in reverse to loosen a bolt or nut in bolt mode.

[0018] In this way, when the motor is rotated in the reverse direction to loosen the tightening of a bolt or nut, when the tightening is loosened and the load on the motor decreases, the motor continues to rotate, preventing the bolt or nut from coming off the tool bit and falling.

[0019] Furthermore, in order to control the motor with this specific control characteristic, the control unit needs to detect a reduction in load when the motor rotates in reverse. The reduction in load can be detected, for example, from a change in the motor's rotation speed or current.

[0020] In addition, if the electric work machine is an electric tool equipped with an impact mechanism that strikes the output shaft, the control unit may be configured to determine that the load has decreased when impacts no longer occur while the motor is being rotated in reverse with the above-mentioned specific control characteristics.

[0021] The setting unit may be configured to set a control characteristic different from the specific control characteristic in a screw fastening mode in which the motor is rotated with a screw fastening tool bit driven by the motor fitted into a groove provided in the head of the screw. In this way, when performing a screw fastening operation, the user can adjust the rotation of the motor by operating the operating unit.

[0022] In this case, the other control characteristics set in the screw tightening mode may include a plurality of control characteristics with different maximum rotation speeds of the motor. In this way, the user can easily carry out the screw tightening operation. The maximum rotation speed of the motor during operation can be selected according to working conditions such as the size of the screw or the type of object, or according to the user's preference. [Brief description of the drawings]

[0023] [Figure 1] 1 is a perspective view showing an overall configuration of a rechargeable impact driver according to an embodiment; [Diagram 2] FIG. 2 is a block diagram showing an electrical configuration of the motor drive device. [Diagram 3] 4 is a plan view showing the arrangement of switches and LEDs on an operation panel. FIG. [Figure 4] 4A is a graph showing the control characteristics used for motor rotation control in a control unit, and FIG. 4B is a map used for rotation control based on the control characteristics. [Diagram 5]5 is a time chart showing changes in rotation speed during normal operation when the motor is controlled using the control characteristics shown in FIG. 4. [Figure 6] 4 is a time chart showing the change in rotation speed when the motor is controlled with the control characteristics of the TEX mode. [Figure 7] 6 is a time chart showing changes in rotation speed when the motor is controlled with the control characteristics of the wood mode. [Figure 8] 6 is a time chart showing a change in the rotation speed when the motor is controlled with a control characteristic that rotates the motor in reverse in a voltage mode. [Figure 9] 4 is a flowchart showing the first half of a motor control process. [Figure 10] 13 is a flowchart showing a second half of the motor control process. [Figure 11] 11 is a flowchart showing a switch operation confirmation process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following description, "TEKS" is a registered trademark. In this embodiment, a rechargeable impact driver 1, which is one type of power tool, will be described as an electric working machine according to the present disclosure.

[0025] 1, the rechargeable impact driver 1 is configured by assembling left and right half housings 2, 3, and includes a main housing 5 with a grip section 4 extending downward. The main housing 5 includes a battery attachment section 9 at the lower end of the grip section 4 for detachably attaching a battery pack 6.

[0026] The rear of the main housing 5 (right side in Figure 1) is a motor storage section 7 that houses a motor 30 (see Figure 2) that serves as the power source for the rechargeable impact driver 1, and a reduction mechanism and an impact mechanism are housed in front of the motor storage section 7.

[0027] At the tip of the main body housing 5, a chuck sleeve 8 is provided for mounting various tool bits (not shown) such as a driver bit or a socket bit on an output shaft driven by a motor 30.

[0028] The impact mechanism includes, for example, a spindle that is rotated via a reduction mechanism, a hammer that rotates together with the spindle and is movable in the axial direction, and an anvil located in front of the hammer and having a tool bit attached to its tip.

[0029] That is, in the striking mechanism, when the spindle rotates with the rotation of the motor 30, the anvil rotates via the hammer, thereby rotating the chuck sleeve 8 (and thus the tool bit).

[0030] As the screw is tightened by the tool bit and the load on the anvil increases, the hammer moves backward against the force of the coil spring and comes off the anvil, then rotates with the spindle. At the same time, the spring biases the rod forward and re-engages the anvil.

[0031] As a result, intermittent strikes are applied to the anvil, and the screw is tightened by the tool bit. Note that this striking mechanism is well known, and therefore a detailed description thereof will be omitted here.

[0032] Next, the grip portion 4 is a gripping portion that is held by the user when using the rechargeable impact driver 1, and a trigger 10 is provided on the upper tip side of the grip portion 4. The trigger 10 is to be pulled by the user's finger while the user is holding the grip portion 4.

[0033] The trigger 10 is provided with a main switch 10A (see FIG. 2) that is turned on when the trigger 10 is pulled, and an operation amount detection unit 10B (see FIG. 2) for detecting the amount of pulling (in other words, the amount of operation) of the trigger 10. The operation amount detection unit 10B is configured with a variable resistor whose resistance value changes according to the amount of pulling of the trigger 10.

[0034] In addition, above the trigger 10 (on the upper end side of the grip portion 4), a mode changeover switch 14 is provided as a second setting portion of the present disclosure for changing the operation mode of the rechargeable impact driver 1 to a desired operation mode with a single operation.

[0035] Further, in the grip portion 4, behind the mode changeover switch 14, there is provided a forward / reverse changeover switch 12 for changing the rotation direction of the motor 30 between the forward direction, which is the screw tightening direction, and the reverse direction.

[0036] The main body housing 5 is provided with a pair of left and right illumination LEDs 16 as illumination units that illuminate the front, sandwiching the chuck sleeve 8. The illumination LEDs 16 also function as a second notification unit that lights up when the mode change switch 14 is operated and the operation input is accepted by the control circuit 80 (see FIG. 2) to notify the operation.

[0037] Next, in the main body housing 5, a battery mounting section 9 provided below the grip section 4 is provided with an operation panel 20. The operation panel 20 is provided with an impact force switch 22 and a special switch 26 as a first setting section of the present disclosure for selectively setting the operation mode of the rechargeable impact driver 1 from among eight preset operation modes. The operation panel 20 is also provided with a lighting switch 24 used to turn the lighting LED 16 on and off.

[0038] As shown in FIG. 3, the operation panel 20 is provided with an impact force mode display section 42, a special mode display section 44, and a setting display LED 46 as display sections for displaying the setting state of the operation mode.

[0039] The impact force mode display unit 42 is intended to display the operating mode set via the impact force switch 22, and is provided with four display LEDs for displaying four types of impact force modes that can be switched sequentially by operating the impact force switch 22.

[0040] In addition, the special mode display unit 44 is for displaying the operation mode set via the special switch 26, and is provided with four display LEDs for displaying four types of operation modes that can be switched sequentially by operating the special switch 26.

[0041] The setting display LED 46 indicates whether the current operation mode displayed on the impact force mode display section 42 or the special mode display section 44 is the operation mode set via the mode changeover switch 14. The setting display LED 46 is turned on when the setting is in the ON state, to notify the user of this fact. The setting display LED 46 functions as a first notification unit in the present disclosure.

[0042] The eight operation modes that can be set via the striking force switch 22 and the special switch 26 will be described in detail later with reference to FIGS. Next, in this embodiment, the battery housed in the battery pack 6 is a rechargeable secondary battery, such as a lithium ion battery.

[0043] In this embodiment, the motor 30 is a three-phase brushless motor having armature windings of U, V, and W phases. The motor 30 is provided with a rotation sensor 32 (see FIG. 2) for detecting the rotational position (angle) of the motor 30.

[0044] The rotation sensor 32 is, for example, configured with a Hall IC or the like that has three Hall elements arranged corresponding to each phase of the motor 30 and is configured to generate a rotation detection signal for each predetermined rotation angle of the motor 30.

[0045] Inside the grip portion 4, a motor drive device 50 (see FIG. 2) is provided which receives power from the battery pack 6 and controls the drive of the motor 30. As shown in FIG. 2, the motor drive device 50 includes a drive circuit 52, a current detection circuit 56, a rotor position detection circuit 58, a display circuit 60, a control circuit power supply circuit 62, and a control circuit 80.

[0046] The drive circuit 52 receives power from the battery pack 6 and passes current through each phase winding of the motor 30, and in this embodiment is configured as a three-phase full-bridge circuit made up of six switching elements Q1 to Q6. In this embodiment, each of the switching elements Q1 to Q6 is a MOSFET.

[0047] In the drive circuit 52, the three switching elements Q1 to Q3 are provided between the terminals U, V, and W of the motor 30 and a power supply line connected to the positive electrode side of the battery pack 6 as so-called high-side switches.

[0048] The other three switching elements Q4 to Q6 are provided between the terminals U, V, and W of the motor 30 and a ground line connected to the negative electrode of the battery pack 6 as so-called low-side switches.

[0049] A capacitor C1 is provided in the power supply path from the positive electrode side of the battery pack 6 to the drive circuit 52 to suppress voltage fluctuations in the battery voltage. A switching element Q7 for connecting / disconnecting the power supply path from the drive circuit 52 to the negative electrode of the battery pack 6, and a resistor R1 for current detection are provided in the power supply path from the drive circuit 52 to the negative electrode of the battery pack 6. The current detection circuit 36 ​​outputs the voltage across the resistor R1 to the control circuit 80 as a current detection signal.

[0050] Next, the rotor position detection circuit 58 detects the rotational position of the motor 30 based on a detection signal from the rotation sensor 32 , and outputs a detection signal of the rotational position to the control circuit 80 .

[0051] In addition, the display circuit 60 is configured to light up the LEDs provided on the impact force mode display section 42 and the special mode display section 44 of the operation panel 20, the setting display LED 46, and the pair of lighting LEDs 16 on the left and right in accordance with instructions from the control circuit 80.

[0052] The control circuit power supply circuit 62 supplies power to each section in the motor drive device 50, and generates a predetermined power supply voltage (constant voltage) Vcc by receiving power from the battery pack 6. The generated power supply voltage Vcc is then supplied to the control circuit 80, the display circuit 60, pull-up resistors provided in the input paths from the various switches described above, and the like.

[0053] In addition, when the power supply circuit 62 for the control circuit is stopped, it starts up when the main switch 10A is turned on, and stops operating when the operation of the main switch 10A, the mode change switch 14, the impact force switch 22, or the special switch 26 is stopped for a certain period of time or more.

[0054] Next, the control circuit 80 is configured with a microcomputer including a CPU, ROM, RAM, etc., and is provided with a storage unit 92 in which the control characteristics of the motor 30 in each of the above-mentioned operation modes are stored. The storage unit 92 is configured with a non-volatile memory in which data can be rewritten.

[0055] In addition, the control circuit 80 is connected to the main switch 10A, the operation amount detection unit 10B, the forward / reverse changeover switch 12, the mode changeover switch 14, the impact force switch 22, the lighting switch 24, and the special switch 26.

[0056] The control circuit 80 functions as a SW input unit 82, a speed command unit 84, a display control unit 86, a rotation speed calculation unit 88, a PWM generation unit 90, and a motor drive control unit 94 under the program executed by the CPU.

[0057] The SW input unit 82 detects the on / off states of the main switch 10A, the mode change switch 14, the impact force switch 22, the lighting switch 24, and the special switch 26, and sets the above-mentioned operating mode and the on / off state of the various LEDs.

[0058] The operation mode set by the SW input unit 82 is stored in the storage unit 92 and is used by the PWM generation unit 90 to generate a PWM signal. The on / off states of the various LEDs are output to the display control unit 86. The display control unit 86 controls the on / off states of the various LEDs via the display circuit 60 in accordance with the input from the SW input unit 82.

[0059] Further, the speed command section 84 detects the amount of operation of the trigger 10 based on an input signal from the operation amount detection section 10B, and outputs it to the PWM generation section 90 as a speed command for driving the motor. Furthermore, the rotation speed calculation unit 88 calculates the rotation speed of the motor 30 based on the detection signal from the rotor position detection circuit 58 , and outputs the calculation result to the PWM generation unit 90 .

[0060] Next, the PWM generating unit 90 reads out from the storage unit 92 the control characteristics corresponding to the operation mode set by the SW input unit 82, and generates a PWM signal that is a control signal for driving the motor 30 in accordance with the control characteristics.

[0061] In other words, the PWM generation unit 90 generates a PWM signal based on the control characteristics read from the memory unit 92, the speed command input from the speed command unit 84 (in other words, the operation amount of the trigger 10), and the rotational speed of the motor 30 input from the rotational speed calculation unit 88.

[0062] In addition, the PWM generation unit monitors the current flowing through the motor 30 based on the detection signal from the current detection circuit 56, and when an overcurrent flows through the motor 30, it instructs the motor drive control unit 94 to stop or reduce the rotation of the motor 30.

[0063] Next, the motor drive control unit 94 controls the motor drive by turning on / off the switching elements Q1 to Q6 constituting the drive circuit 52 in accordance with the PWM signal generated by the PWM generation unit 90. A current flows through each phase winding of the motor 30, causing the motor 30 to rotate.

[0064] The input signal from the forward / reverse changeover switch 12 is input to a motor drive control section 94, which switches the rotation direction of the motor 30 based on the input signal. Next, the operation modes that are set via the striking force switch 22 and the special switch 26 will be described.

[0065] As shown in FIG. 3, the rechargeable impact driver 1 of this embodiment has four impact force modes, namely, "fastest," "strong," "medium," and "weak," as well as four special modes, namely, "wood," "bolt," "texture (thin)," and "texture (thick)."

[0066] These operating modes define the control method for the motor 30, and in order to realize the control method defined in each operating mode, the control characteristics required to control the motor 30 in each operating mode are pre-stored (registered) in the memory unit 92.

[0067] The four impact force modes, namely “fastest”, “strong”, “medium” and “weak”, can be switched in sequence from fastest to strong to medium to weak to fastest, etc. by operating the impact force switch 22.

[0068] In addition, the four special modes of "Wood," "Bolt," "Texture (thin)," and "Texture (thick)" can be switched sequentially by operating the special switch 26, in the following order: Wood → Bolt → Texture (thin) → Texture (thick) → Wood...

[0069] 4A and 4B, the four impact force modes of "fastest", "strong", "medium" and "weak" are common screw tightening modes. In these four impact force modes, control characteristics are set for setting the duty ratio of the control signal (PWM signal) when the motor 30 is driven according to the pull amount (operation amount) of the trigger 10.

[0070] In other words, the control characteristics in the fastest impact force mode are set such that, for example, when the trigger pull amount is divided into 10 levels from "1" to "10," the duty ratio of the PWM signal becomes maximum in the "10" range, which is the largest trigger pull amount, and motor 30 is rotated at the fastest speed.

[0071] The control characteristics in the "strong", "medium", and "weak" impact force modes are set so that the duty ratio of the PWM signal decreases in order in the "10" region, where the trigger pull is the greatest. Therefore, in the "strong", "medium", and "weak" impact force modes, the maximum rotation speed of the motor 30 when the user operates the trigger 10 to the maximum pull amount becomes smaller in order compared to the "fastest" impact force mode.

[0072] Furthermore, the control characteristics in the impact force mode are such that when the trigger pull amount reaches the minimum pull amount of "1" regardless of whether it is "fastest," "strong," "medium," or "weak," the duty ratio of the PWM signal reaches a minimum value close to 0. As the trigger pull amount increases from "1," the duty ratio is set to gradually increase until it reaches the value when the trigger pull amount reaches "10."

[0073] Therefore, in the impact force mode, the operating range in which the trigger pull amount is "1" or more becomes the effective operating range in which the motor 30 can be driven, and within that effective operating range, the area up to when the trigger pull amount reaches "10" becomes the control range in which the rotation speed of the motor 30 can be adjusted.

[0074] As a result, when the trigger 10 is pulled in the impact force mode, the rotation speed of the motor 30 gradually increases due to so-called soft start control, as shown in FIG. 5, until the motor 30 is in an unloaded state. If so, the number of rotations will be constant according to the amount of pulling of the trigger 10.

[0075] When a load is applied to the motor 30 by tightening a screw, etc., the rotation speed of the motor 30 decreases in accordance with the load, and when an impact occurs thereafter, the load applied to the motor 30 temporarily decreases, causing the rotation speed of the motor 30 to fluctuate.

[0076] In the above explanation, an example was given in which the trigger pull amount was divided into 10 stages and the effective operation range and control range were set, but the effective operation range and control range may be set appropriately for the entire operation area of ​​the trigger 10 and are not limited to the above setting method.

[0077] Next, among the special modes, the texture modes "Texture (thin)" and "Texture (thick)" are operating modes for tightening texture screws, which have a drill at the tip for drilling a screw hole in the workpiece.

[0078] In the texture (thick) mode, as shown in Fig. 6, after the motor 30 starts to drive, until an impact occurs, the motor is driven by a PWM signal with a predetermined duty ratio according to the amount of pulling of the trigger 10, just like in the impact force mode. Then, when an impact occurs a predetermined number of times, it is determined that a screw hole has been formed in the workpiece, and the duty ratio of the PWM signal is reduced, and the rotation speed of the motor 30 is reduced.

[0079] As a result, after the motor 30 starts to operate, the motor 30 is rotated at high speed until a screw hole is formed in the workpiece, and then the rotation speed of the motor 30 is reduced, thereby enabling stable screw tightening.

[0080] The impact can be detected, for example, from the number of revolutions or current fluctuations (amplitude) of the motor 30, or vibrations applied to the power tool. Furthermore, whether a screw hole has been successfully formed with the tex screw can be determined not only from the number of impacts, but also from the time that has elapsed since the impact was detected. The threshold value used to determine the impact may be changed according to the driving state of the motor, such as the battery voltage or the number of revolutions of the motor.

[0081] In addition, the difference between "Texture (thin)" and "Texture (thick)" in the texture mode is the thickness of the workpiece, and the user can select as appropriate. In the TEX (thin) mode, the workpiece is thinner than in the TEX (thick) mode, so that the workpiece can be drilled and fastened with the TEX screw in a short time. For this reason, in the TEX (thin) mode, the motor 30 is set to stop driving when a predetermined number of strikes are generated after the motor starts driving.

[0082] In the special mode of "wood" (wood mode), when the trigger 10 is pulled, the duty ratio of the PWM signal is set according to the amount of pulling. This duty ratio is set to be smaller than that of the "fastest" impact force mode, such as the "low speed" or "medium speed" impact force mode.

[0083] Then, when a predetermined number of impacts occur after the motor 30 starts to drive, the duty ratio of the PWM signal is gradually increased as shown in Fig. 7. This is because, when fastening a screw into wood, the screw has not yet penetrated the wood immediately after the motor 30 starts to drive, and so the screw needs to be rotated slowly to penetrate the wood.

[0084] That is, in the wood mode, the motor 30 is driven at a low rotation speed after it starts to drive, and then, when a predetermined number of strikes have been generated, it is assumed that the screw has penetrated into the wood, and the rotation speed of the motor 30 is gradually increased. As a result, the screw can be fixed and tightened efficiently in a short time. It will be possible to implement it.

[0085] Next, among the special modes, the bolt mode is an operation mode for tightening or loosening a bolt (or nut). In other words, when the motor 30 is rotated to tighten or loosen a bolt (or nut), the tool bit is fitted onto the head of the bolt (or nut), so the tool bit will not come off the bolt (or nut) as occurs when tightening a screw.

[0086] For this reason, in the volt mode, as shown in Figures 3A and 3B, the control characteristics are set so that the trigger pull amount at which the duty ratio of the PWM signal (in other words, the rotation speed of the motor 30) is maximized is smaller than the pull amount in the impact force mode.

[0087] In other words, in the volt mode, the control characteristics of the motor 30 are set as the specific control characteristics of the present disclosure so that the duty ratio of the PWM signal (in other words, the rotation speed of the motor 30) is maximized when the trigger pull amount is "4" or more.

[0088] In addition, in the bolt mode, in order to enable the bolt (or nut) to be tightened or loosened quickly, the duty ratio of the PWM signal when the trigger pull amount becomes "4" or more is set to the same (or approximately the same) maximum value as in the "fastest" impact force mode.

[0089] Therefore, in the bolt mode, compared to the fastest operating mode, even a slight pull of the trigger 10 causes the motor 30 to rotate at the fastest speed, allowing the bolt (or nut) to be tightened or loosened efficiently in a short time.

[0090] In addition, the user can rotate the motor at high speed without pulling the trigger 10 nearly to the maximum pulling amount, which prevents the user's fingers from getting tired due to the operation of the trigger 10 when tightening or loosening a bolt (or nut), making it impossible to continue the work for a long time.

[0091] In addition, in the bolt mode, when the motor 30 is rotated in the reverse direction to loosen the tightening of a bolt (or a nut), a load is applied from the bolt (or a nut) when the driving of the motor 30 starts, and an impact occurs immediately.

[0092] When the bolt (or nut) is loosened by the impact, the load applied to the motor 30 decreases, and the rotation speed of the motor 30 increases. Therefore, in the bolt mode, when the motor 30 rotates in reverse, as shown in FIG. 8, the control characteristics are set so that an impact is detected after the drive of the motor 30 starts, and then, when no impact is detected for a predetermined period of time, the drive of the motor 30 is stopped (or reduced).

[0093] Therefore, when loosening the fastening of the bolt (or nut), it is possible to prevent the bolt (or nut) from falling off the tool bit due to the motor 30 being rotated more than necessary. Since a decrease in the load applied to the motor 30 can also be detected by a change in the rotation speed or current of the motor 30, these parameters may be used instead of impact to detect a decrease in the load applied to the motor 30. In this way, even an electric operating machine that does not have an impact mechanism can drive the motor 30 with the control characteristics of the bolt mode.

[0094] Next, the control process executed in the control circuit 80 to control the rotation of the motor 30 is 2 are realized by a CPU constituting the control circuit 80 executing a control process (program) which will be described below.

[0095] As shown in Figures 9 and 10, when the control circuit 80 is started and the CPU starts the control process, first, in S110, various settings such as the currently set operation mode and the control characteristics in that operation mode are read from the memory unit 92.

[0096] Then, in the next S120, it is determined whether or not the trigger 10 is operated based on the input signal from the main switch 10A. If the trigger 10 is operated, the process proceeds to S130, and a drive process for driving the motor 30 is executed.

[0097] In this drive process, in S131, the amount of pulling (operation amount) of the trigger 10 is obtained from the operation amount detection unit 10B, and in S132, various calculation processes are performed for controlling the motor 30 based on the control characteristics read out in S110.

[0098] Next, in S133, the duty ratio (command PWM duty) of the PWM signal, which is a control signal for driving the motor 30, is determined based on the calculation result in S132. Then, in the following S134, the motor drive control unit 94 executes a PWM output process of turning on / off each of the switching elements Q1 to Q6 constituting the drive circuit 52 with a PWM signal having the duty ratio determined in S133, and then proceeds to S120.

[0099] On the other hand, if it is determined in S120 that the trigger 10 has not been operated, the operation states of the mode changeover switch 14, the striking force switch 22, and the special switch 26 are successively confirmed in S140, S150, and S160.

[0100] The confirmation processes in S140, S150, and S160 not only confirm the on / off state of the target switch, but also determine whether the switch was pressed for a long time or a short time based on the operation (pressing) time of the switch.

[0101] Therefore, the confirmation processes in S140, S150, and S160 are executed according to the procedure shown in FIG. That is, in the confirmation processes of S140, S150, and S160, first, in S411, it is determined whether the target switch is in the on or off state, and if the switch is in the off state, the process proceeds to S412 and an on counter for measuring the on time is cleared.

[0102] In the next step S413, the off-time is measured by incrementing the off-counter, and in the next step S414, it is determined whether the time measured by the off-counter (off-time) has exceeded a predetermined time (for example, 10 ms).

[0103] If it is determined in S414 that the OFF time has not exceeded the predetermined time, the confirmation process is temporarily terminated, and if it is determined in S414 that the OFF time has exceeded the predetermined time, the process proceeds to S415.

[0104] In S415, it is determined whether the switch is currently being judged to be on, and if it is not currently being judged to be on, in S416 the short press judgment of the switch is turned off, and in S419 the long press judgment of the switch is turned off. Then, in the following S420, it is stored that the switch is currently being judged to be off, and the confirmation process is temporarily terminated.

[0105] Also, if it is determined in S415 that the switch is currently being turned on, the process proceeds to S417. It is determined whether or not the switch is being judged for a long press (long press judgment ON). If the switch is being judged for a long press, the process proceeds to S419, and if the switch is not being judged for a long press, the process proceeds to S418, where the short press judgment is turned ON, and then the process proceeds to S419.

[0106] Also, if it is determined in S411 that the switch is in the on state, the process proceeds to S421, where an off counter for measuring the off time of the switch is cleared, and in the following S422, the on counter is incremented to measure the on time.

[0107] Next, in S423, it is determined whether the time counted by the on counter (on time) has exceeded a predetermined time (for example, 10 ms). If it is determined that the on time has not exceeded the predetermined time, the process proceeds to S425, and if it is determined that the on time has exceeded the predetermined time, the process proceeds to S425 after storing that the switch is currently being determined to be on.

[0108] In S425, it is determined whether the on-time of the switch exceeds a set time for long press judgment (for example, 1 sec). If the on-time does not exceed the set time for long press judgment, the confirmation process is temporarily terminated, and if the on-time exceeds the set time for long press judgment, it is determined that the switch has been pressed for a long time, and in S426, the long press judgment is turned on, and the confirmation process is temporarily terminated.

[0109] In this way, in the confirmation process of S140, S150, and S160, when the target switch is operated to the ON state, the ON time is measured, and based on the measured time, it is determined whether the switch has been pressed long or not. Also, if a long press is not determined and the switch is turned to the OFF state, it is determined that the switch has been pressed shortly after the OFF state has elapsed for a predetermined time.

[0110] Thus, when the operational states of the mode change switch 14, the impact force switch 22, and the special switch 26 are confirmed in the confirmation processes of S140, S150, and S160, the process proceeds to S170, where it is determined whether the mode change switch 14 has been pressed and held.

[0111] If the mode changeover switch 14 is pressed and held down, the process proceeds to S180, where it is determined whether the impact force switch 22 is also pressed and held down, and if the impact force switch 22 is also pressed and held down, the process proceeds to S190.

[0112] In S190, the currently set operation mode is stored (registered) in the storage unit 92 as the operation mode to be switched by operating the mode change switch 14 (registered mode). That is, in this embodiment, when the mode changeover switch 14 and the striking force switch 22 are pressed and held simultaneously, the operation mode (registered mode) to be switched by the operation of the mode changeover switch 14 is registered in the storage unit 92.

[0113] Then, when the registration mode is registered in the memory unit 92 in this manner, the process proceeds to S200, and, for example, the LED of the current operating mode displayed on the operation panel 20 and the setting display LED 46 are caused to flash during a long press operation to notify that the registration mode has been set or updated.

[0114] Next, when the notification in S200 ends, or when it is determined in S170 that the mode changeover switch 14 has not been pressed for a long time, or when it is determined in S180 that the impact force switch 22 has not been pressed for a long time, the process proceeds to S210 shown in FIG. 10.

[0115] In S210, it is determined whether or not the mode change switch 14 has been short-pressed. If the mode change switch 14 has not been short-pressed, the process proceeds to S290, and if the mode change switch 14 has been short-pressed, the process proceeds to S220.

[0116] In S220, it is determined whether the operation mode (in other words, the control characteristics) currently set for motor control is the registered mode. If the currently set operation mode is not the registered mode, the currently set operation mode, i.e., the operation mode set via the impact force switch 22 or the special switch 26, is stored in the memory unit 92 as the previous value, and the process proceeds to S240.

[0117] In S240, the operation mode for motor control is switched to the registration mode by selecting the registration mode set in S190. Then, in the following S250, the setting display LED 46 of the operation panel 20 is turned on to notify the user of this, and the process proceeds to S260.

[0118] Furthermore, if it is determined in S220 that the registered mode is not currently set as the operating mode for motor control, the process proceeds to S270, where the operating mode stored as the previous value in the memory unit 92 is read out and set as the operating mode for motor control.

[0119] Then, in the next S280, the setting display LED 46 is turned off to notify the user that the current operation mode is not the registration mode switched to by the operation of the mode changeover switch 14, and the process proceeds to S260.

[0120] Also, in S260, the illumination LED 16 is caused to blink for a certain period of time to notify that the operation mode has been switched by operating the mode change switch 14, and the process proceeds to S290.

[0121] Next, in S290, it is determined whether the impact force switch 22 has been short-pressed, and if the impact force switch has not been short-pressed, the process proceeds to S320 to determine whether the special switch 26 has been short-pressed, and if the special switch 26 has not been short-pressed, the process proceeds to S120 in Fig. 9 to execute the above series of processes again.

[0122] Furthermore, if it is determined in S290 that the impact force switch 22 has been pressed for a short time, the process proceeds to S300. In S300, the next operation mode to the operation mode currently selected as the impact force mode is selected from among the four operation modes that can be set as the impact force mode: "fastest," "strong," "medium," and "weak."

[0123] In addition, in S300, the selected operation mode is set as the operation mode for motor control, thereby switching the operation mode, and the process proceeds to S310. In S300, the current operation mode after switching is stored in the storage unit 92. In addition, the current operation mode is notified by lighting up the LED corresponding to the currently set impact force mode among the four LEDs provided on the impact force mode display unit 42.

[0124] Then, in the next S310, the setting display LED 46 is turned off to notify the user that the current operation mode is not the registration mode switched to by operating the mode change switch 14, and the process proceeds to S320.

[0125] If it is determined in S320 that the special switch has been pressed briefly, the process proceeds to S330. In S330, the next operation mode after the operation mode currently selected as the special mode is selected from among the four operation modes that can be set as special modes: "Wood," "Bolt," "Texture (thin)," and "Texture (thick)."

[0126] In addition, in S330, the selected operation mode is set as the operation mode for motor control, thereby switching the operation mode, and the process proceeds to S340. In S330, similarly to S300, the operating mode after switching is stored in memory unit 92, and the current operating mode is notified by lighting up one of the four LEDs provided in special mode display unit 44 that corresponds to the currently set special mode.

[0127] Then, in the next S310, the setting display LED 46 is turned off to notify the user that the current operation mode is not the registration mode switched to by operating the mode changeover switch 14, and the process proceeds to S120 in FIG.

[0128] As described above, in the rechargeable impact driver 1 of this embodiment, the memory unit 92 stores eight types of operation modes (control characteristics) that define the control method for the motor 30. The user can select the operation mode to be used for motor control from among the eight operation modes by operating the impact force switch 22, the special switch 26, or the mode change switch 14.

[0129] Furthermore, the striking force switch 22 and the special switch 26 can be operated by the user to sequentially switch between the four operating modes (striking force mode and special mode) corresponding to each switch.

[0130] In response to this, the mode changeover switch 14 can register in advance the operation modes that can be switched by operating it as registered modes. Also, every time the user operates the mode changeover switch 14, the operation mode used for motor control can be alternately switched between the special mode and the operation mode set via the impact force switch 22 or the special switch 26.

[0131] Therefore, by registering a desired operation mode as a registered mode, the user can extremely easily switch between operation modes, thereby improving the usability of the rechargeable impact driver 1.

[0132] Furthermore, among the above eight operating modes, in the volt mode, like the fastest mode, the motor 30 can be driven at maximum speed, but the amount of pulling of the trigger 10 required to achieve the maximum speed is set to be less than in the fastest mode.

[0133] Specifically, the control characteristics of the volt mode are set so that the duty ratio of the PWM signal is maximized when the trigger 10 is pulled by an amount equal to or less than 50 (approximately 40% in this embodiment) within the effective operating range in which the motor 30 can be driven by pulling the trigger 10. Therefore, the rotation speed of the motor 30 also becomes maximum at this pulling amount.

[0134] Therefore, when tightening or loosening a bolt (or a nut), the user does not need to fully pull the trigger 10, improving operability. Although the embodiments for carrying out the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and can be carried out in various modified forms.

[0135] For example, in the above embodiment, the rechargeable impact driver 1 has been described as an example of an electric working machine of the present disclosure. However, as long as the electric working machine of the present disclosure is an electric working machine that includes a motor as a power source and is configured to control the rotation speed of the motor according to the amount of operation of an operating unit such as a trigger, it can be applied in the same manner as in the above embodiment and can achieve the same effects.

[0136] In addition, in the above embodiment, the motor 30 is described as being configured as a three-phase brushless motor, but the technology disclosed herein can be applied even if the power source of the electric work machine is a brushed motor or an AC motor.

[0137] In addition, multiple functions possessed by one component in the above embodiments may be realized by multiple components, or one function possessed by one component may be realized by multiple components. Also, multiple functions possessed by multiple components may be realized by one component, or one function realized by multiple components may be realized by one component. Also, a part of the configuration of the above embodiment may be omitted. Also, at least a part of the configuration of the above embodiment may be added to or substituted for the configuration of another of the above embodiments. Note that any aspect included in the technical idea identified only by the wording described in the claims is an embodiment of the present disclosure. [Explanation of symbols]

[0138] 1...Rechargeable impact driver, 4...Grip section, 5...Main body housing, 6...Battery pack, 9...Battery mounting section, 10...Trigger, 10A...Main switch, 10B...Operation amount detection section, 12...Forward / reverse switch, 14...Mode switch, 16...Lighting LED, 20...Operation panel, 22...Impact force switch, 24...Illumination switch, 26...Special switch, 30...Motor, 32...Rotation sensor, 36...Current detection circuit, 42...Impact force mode display section, 44...Special mode display section, 46...Setting display LED, 50...Motor drive device, 52...Drive circuit, 56...Current detection circuit, 58...Rotor position detection circuit, 60...Display circuit, 62...Power supply circuit for control circuit, 80...Control circuit, 82...Switch input section, 84...Speed ​​command section, 86...Display control section, 88...Rotation speed calculation section, 90...PWM generation section, 92...Storage section, 94...Motor drive control section

Claims

1. A motor; a mounting portion for mounting a tool bit; an anvil that rotates the tool bit attached to the attachment portion by rotation of the motor; a hammer that rotates together with the anvil and strikes the anvil by disengaging and reengaging with the anvil when a load applied to the anvil from the tool bit increases; an operation unit for instructing the motor to be driven or stopped by a user; A control unit that drives the motor in response to an operation of the operation unit; An impact driver comprising: an operation mode setting switch that is operated by a user to switch and set an operation mode of the impact driver between a first mode and a second mode; a forward / reverse changeover switch that is operated by a user to set the rotation direction of the motor to either a forward direction for fastening an object with the tool bit or a reverse direction for loosening the fastening of the object; Equipped with the operation mode setting switch includes an impact force switch for setting one of a plurality of impact forces including a first impact force that is the largest impact force and a second impact force that is smaller than the first impact force setting, as the impact force by the hammer when the operation mode is the first mode, The control unit is When the operation mode is set to the first mode, the motor is driven in a rotation direction set by the forward / reverse changeover switch so that the rotation speed of the motor increases according to the impact force set by the impact force switch as the operation amount of the operation unit increases, When the operation mode is set to the second mode, when the operation unit is operated, the motor is driven in a rotation direction set by the forward / reverse changeover switch so that the rotation speed of the motor reaches a rotation speed corresponding to a maximum rotation speed in the first mode with a smaller operation amount than in the first mode, Moreover, when the operation mode is set to the second mode, the control characteristic of the motor by the control unit to cause the rotation speed of the motor to reach the maximum rotation speed is the same when the rotation direction of the motor is the forward direction and when the rotation direction is the reverse direction, The control unit of this impact driver is configured to stop or reduce the rotation of the motor when the load applied to the motor decreases while the motor is rotating in the reverse direction in the second mode.

2. The impact driver according to claim 1 , wherein the control unit is configured to detect a reduction in the load applied to the motor from a change in a rotation speed or a current of the motor.

3. 3. The impact driver according to claim 1, wherein the operation mode setting switch is configured to set, as the first mode, a screw tightening mode in which the motor is rotated with the tool bit fitted into a groove provided in the head of a screw, and to set, as the second mode, a bolt mode in which the motor is rotated with the tool bit fitted around a bolt or a nut.

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