Reciprocating tool, and method for holding energization in electric motor of reciprocating tool

Abstract

To provide a technique capable of holding energization in an electric motor with a simple configuration even after a manual switch for a reciprocating tool is turned off.SOLUTION: A reciprocating tool includes a reciprocating member, an electric motor, a transmission device, a drive circuit, a first manual switch, a switch element and a control circuit. A first contact point of the first manual switch is connected to a power supply, and a second contact point of the first manual switch is connected to the drive circuit. The first manual switch in its on state connects the first contact point to the second contact point. The switch element (i) is turned on when it receives an electric signal, and (ii) establishes electrical continuity between the first contact point and the second contact point in its on state. In response to at least the first manual switch being turned on, the control circuit continues to output the electric signal to the switch element until the drive of the electric motor is stopped.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a reciprocating tool. [Background technology]

[0002] The following Patent Document 1 discloses a driving tool equipped with a start-up state locking mechanism. The start-up state locking mechanism has a mechanical function of locking the driving tool's power switch in the on state to keep the driving tool's electric motor in the started state (energized state). This start-up state locking mechanism keeps the electric motor in the started state for a certain period of time after the user releases the on operation of the trigger after the driving operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-58080 Summary of the Invention [Problem to be solved by the invention]

[0004] The above-described start-up locking mechanism is a mechanical mechanism that requires many mechanical parts. If the start-up locking mechanism can be simplified, it can facilitate the miniaturization and weight reduction of the above-described driving tool.

[0005] Therefore, an object of one aspect of the present disclosure is to provide a technique that can maintain the power supply to an electric motor in a reciprocating tool with a simple configuration even after a manual switch is turned off. [Means for solving the problem]

[0006] In this disclosure, terms such as "first" and "second" are intended only to distinguish elements from one another and are not intended to limit the order or number of elements. Thus, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. In addition, a first element may be included without a second element, and similarly, a second element may be included without a first element.

[0007] One aspect of the present disclosure provides a reciprocating tool including a reciprocating member, an electric motor, a transmission device, a drive circuit, a first manual switch, a switch element, and a control circuit.

[0008] The reciprocating member is configured to reciprocate between a first dead center and a second dead center. The electric motor is configured to generate a driving force. The transmission device is configured to transmit the driving force of the electric motor to the reciprocating member at least during the stroke of the reciprocating member from the second dead center to the first dead center.

[0009] The drive circuit is configured to (i) receive current from a power source and (ii) drive the electric motor with the received current. The first manual switch (i) has a first contact and a second contact, and (ii) is configured to be manually turned on or off by a user of the reciprocating tool. The first contact is connected to a power source. The second contact is connected to a drive circuit. The first manual switch (i) is configured to connect the first contact to the second contact in its on state, and (ii) is configured to disconnect the first contact from the second contact in its off state.

[0010] The switch element is configured to (i) be turned on upon receiving an electrical signal, (ii) in its on state, establish electrical continuity between the first contact and the second contact, and (iii) in its off state, interrupt electrical continuity between the first contact and the second contact.

[0011] The control circuit is configured to continue to output an electric signal to the switch element in response to at least the first manual switch being turned on until the driving of the electric motor is stopped.

[0012] In the reciprocating tool configured as described above, when the first manual switch is manually turned on, the switch element maintains electrical continuity between the first contact and the second contact of the first manual switch until the driving of the electric motor is stopped. As a result, even if the first manual switch is turned off before the driving of the electric motor is stopped, current continues to be supplied from the power source to the drive circuit, and the electric motor can be kept energized.

[0013] Therefore, in this reciprocating tool, the power supply to the electric motor can be maintained by a switch element that is much simpler than a mechanical mechanism. Another aspect of the present disclosure is a method for maintaining energization of an electric motor in a reciprocating tool, the method comprising: connecting a first contact of the manual switch to a power source; connecting a second contact of a manual switch to a drive circuit, the manual switch being configured (i) to be manually turned on or off by a user of the reciprocating tool, (ii) in its on state, to connect the first contact to the second contact, and (iii) in its off state, to disconnect the first contact from the second contact; and the drive circuit being configured (i) to receive current from a power source and (ii) to drive the electric motor with the received current; The first contact and the second contact are connected via a switch element, the switch element being configured to (i) be turned on in response to an electric signal, (ii) in its on state, establish conduction between the first contact and the second contact, and (iii) in its off state, cut off conduction between the first contact and the second contact; In response to at least the manual switch being turned on, an electric signal is continuously output to the switch element until the driving of the electric motor is stopped. The present invention provides a method comprising:

[0014] According to this method, the electric motor in the reciprocating tool can be maintained energized by a switch element that is much simpler than a mechanical mechanism. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is an external view of a reciprocating tool according to an exemplary embodiment; [Figure 2] FIG. 2 is a central longitudinal cross-sectional view of the reciprocating tool. [Figure 3A-3B] 3A is a cross-sectional view taken along line IIIA-IIIA in FIG. 1, and FIG. 3B is a top view of the reciprocating tool including a perspective view of a motor housing portion. [Figures 4A-4D] 1 shows one sequence of mechanical movements in a reciprocating tool. [Figures 5A-5E] 1 illustrates the movement of the holder corresponding to one sequence of mechanical movements in a reciprocating tool. [Figure 6] FIG. 2 is a circuit diagram showing an electrical configuration of the reciprocating tool. [Figure 7] 4 is a timing chart showing an outline of the electrical operation of the reciprocating tool. [Figure 8] 4 is a flowchart showing a flow of a main routine executed by a control circuit. [Figure 9] 4 is a flowchart showing the flow of a motor control process executed by a control circuit. DETAILED DESCRIPTION OF THE INVENTION

[0016] 1. Overview of the embodiment Some embodiments may provide a reciprocating tool comprising at least one of the following: Feature 1: A reciprocating member configured to reciprocate between a first dead center and a second dead center; Feature 2: an electric motor configured to generate a driving force; Feature 3: A transmission device configured to transmit the driving force of the electric motor to the reciprocating member at least during the stroke of the reciprocating member from the second dead center to the first dead center; Feature 4: A drive circuit configured to (i) receive current from a power source and (ii) drive an electric motor with the received current; Feature 5: (i) a first manual switch including a first contact and a second contact, and (ii) a first manual switch configured to be manually turned on or off by a user of the reciprocating tool; Feature 6: The first contact is connected to a power source; Feature 7: The second contact is connected to the driving circuit; Feature 8: The first manual switch is configured to (i) connect the first contact to the second contact in its on state, and (ii) disconnect the first contact from the second contact in its off state; Feature 9: A switch element configured to (i) be turned on in response to an electric signal, (ii) establish electrical continuity between a first contact and a second contact in the on state, and (iii) interrupt electrical continuity between the first contact and the second contact in the off state; and Feature 10: A control circuit configured (or programmed) to continue outputting an electrical signal to the switch element in response to at least the first manual switch being turned on until the driving of the electric motor is stopped.

[0017] In a reciprocating tool having at least the features 1 to 10, the power supply to the electric motor can be maintained by a switch element that is much simpler than a mechanical mechanism. Examples of reciprocating tools include electric nail guns, electric rebar tying machines, electric rebar cutting machines, electric oilers, and electric air pumps. An example of an electric oiler is an electric grease gun.

[0018] Examples of electric motors include DC motors, AC motors, and stepper motors. Examples of DC motors include brushless DC motors and brushed DC motors. Examples of drive circuits include full-bridge circuits and half-bridge circuits.

[0019] Examples of the first manual switch include a trigger switch, a push button switch, and a tactile switch. The first contact of the first manual switch may be connected to the positive pole of the power supply, or alternatively, the first contact of the first manual switch may be connected to the negative pole of the power supply.

[0020] Examples of the switching element include a semiconductor switch and a mechanical relay. Examples of the semiconductor switch include a field effect transistor (FET), a bipolar transistor, an insulated gate bipolar transistor (IGBT), and a solid state relay (SSR).

[0021] In some embodiments, the control circuitry may be integrated into a single electronic unit or a single electronic device or a single circuit board. In some embodiments, the control circuit may be a combination of two or more electronic circuits or two or more electronic units or two or more electronic devices individually provided on or within the reciprocating tool.

[0022] In some embodiments, the control circuitry may comprise a microcomputer (or microcontroller or microprocessor), hardwired logic, an application specific integrated circuit (ASIC), an application specific general purpose product (ASSP), a programmable logic device (PLD) (e.g., a field programmable gate array (FPGA)), discrete electronic components, and / or combinations thereof.

[0023] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-10: Feature 11: A physical quantity detection circuit configured to detect a physical quantity associated with the first manual switch being turned on; and Feature 12: The control circuit is configured to continue outputting an electric signal to the switch element in response to the physical quantity detection circuit detecting the physical quantity until the driving of the electric motor is stopped.

[0024] In a reciprocating tool having at least features 1 to 12, the control circuit can output an electrical signal to the switch element in response to at least the first manual switch being turned on, without directly detecting that the first manual switch has been turned on.

[0025] Examples of physical quantities include the current flowing from the power supply to the drive circuit, the voltage of the power supply, and the rotation angle of the electric motor. Some embodiments may include, in addition to or instead of at least one of features 1-12: Feature 13: The physical quantity is the current flowing from the power supply to the drive circuit.

[0026] In a reciprocating tool having at least the features 1 to 13, the control circuit can output an electric signal to the switch element in response to a current flowing from the power source to the drive circuit.

[0027] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-13: Feature 14: The control circuit is configured to output at least one pulse width modulation signal having a predetermined period to the drive circuit to control the drive circuit; and Feature 15: The drive circuit is configured to drive the electric motor based on at least one pulse width modulated signal.

[0028] In a reciprocating tool having at least Features 1 to 12, 14, and 15, the control circuit can control the electric motor by at least one pulse width modulated signal.

[0029] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-15: Feature 16: The control circuit is configured to output at least one pulse width modulation signal having an initial duty ratio to the drive circuit before the drive circuit starts the electric motor; and Feature 17: The initial duty ratio is a duty ratio that is greater than zero but is insufficient to start the electric motor.

[0030] In a reciprocating tool having at least Features 1 to 12 and 14 to 17, the physical quantity detection circuit can detect a physical quantity during the ON period of at least one pulse-modulated signal without the drive circuit starting the electric motor.

[0031] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-17: Feature 18: The physical quantity detection circuit is configured to continue to output a predetermined logic value to the control circuit for a time period equal to or longer than a predetermined period of at least one pulse width modulation signal in response to the detection of the physical quantity by the physical quantity detection circuit; and Feature 19: The control circuit is configured to continue outputting an electric signal to the switch element for a period from when the control circuit receives the predetermined logical value until when the driving of the electric motor is stopped.

[0032] In a reciprocating tool having at least the features 1 to 12 and 14 to 19, a predetermined logical value can be continuously output to the control circuit even during the OFF period of at least one pulse width modulation signal.

[0033] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-19: Feature 20: The electric motor is a brushless DC motor having first to third coils; Feature 21: The drive circuit (i) forms at least a part of a full bridge circuit, and (ii) includes first to sixth semiconductor switches connected to the first to third coils; Feature 22: The first to third semiconductor switches are high-side switches in a full-bridge circuit; Feature 23: The fourth to sixth semiconductor switches are low-side switches in a full-bridge circuit; Feature 24: The at least one pulse width modulation signal includes first to sixth pulse width modulation signals corresponding to the first to sixth semiconductor switches, respectively; Feature 25: The control circuit is configured to select a combination of (i) one of the first to third semiconductor switches and (ii) one of the fourth to sixth semiconductor switches such that the drive circuit fails to start the electric motor before the drive circuit starts the electric motor; Feature 26: The control circuit is configured to select a pair of pulse-width modulation signals corresponding to the selected combination from the first to sixth pulse-width modulation signals before the drive circuit starts the electric motor; Feature 27: The control circuit is configured to output the selected pair of pulse width modulation signals to the drive circuit before the drive circuit starts the electric motor; and Feature 28: Each of the pair of pulse width modulation signals has an initial duty cycle.

[0034] Examples of brushless DC motors include three-phase brushless DC motors and four or more phase brushless DC motors. Examples of full-bridge circuits include three-phase full-bridge circuits and four or more phase full-bridge circuits.

[0035] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-28: Feature 29: A pressing member configured to be pressed against the workpiece by a user; Feature 30: A second manual switch configured to be turned on when the pressing member is pressed against the workpiece; and Feature 31: The control circuit is configured to control the drive circuit to start the electric motor based on the fact that both the first manual switch and the second manual switch are turned on.

[0036] In a reciprocating tool having at least features 1 to 10 and 29 to 31, the electric motor can be prevented from being started accidentally when the pressing member is not pressed against the workpiece, that is, when the user is not processing the workpiece.

[0037] Some embodiments may include, in addition to or instead of at least one of features 1-31: Feature 32: The control circuit is configured to start outputting at least one pulse width modulation signal having an initial duty ratio in response to the second manual switch being turned on.

[0038] In a reciprocating tool including at least the features 1 to 12, 14, 15, and 29 to 32, the physical quantity detection circuit can be prevented from detecting a physical quantity before the second manual switch is turned on.

[0039] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-32: Feature 33: The reciprocating tool is configured to be selectively set to any one of a plurality of operating modes, including a first mode; Feature 34: The control circuit is configured to stop outputting the electrical signal in response to (i) the reciprocating tool being set to the first operating mode and (ii) the first manual switch being turned on within a predetermined time after the second manual switch being turned on.

[0040] In a reciprocating tool having at least features 1 to 10, 29 to 31, 33, and 34, while the reciprocating tool is set to the first operating mode, the electric motor can be prevented from being driven in response to the first manual switch being turned on within a predetermined time after the second manual switch is turned on.

[0041] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-34: · Feature 35: A cylinder (or chamber) containing compressed gas within it; Feature 36: (i) a piston within the cylinder, (ii) urging the reciprocating member toward the second dead center by compressed gas; and Feature 37: The reciprocating member is configured to be driven by the piston from the first dead center to the second dead center.

[0042] In a reciprocating tool having at least Features 1-10 and 35-37, the reciprocating member can be moved from the first dead center to the second dead center by pressure applied to the piston from the compressed gas.

[0043] Examples of compressed gases include compressed air and compressed inert gases. Compressed air may be compressed dry air. Examples of compressed inert gases include compressed nitrogen gas and compressed noble gases.

[0044] Some embodiments may include, in addition to or instead of at least one of features 1-37, the following: Feature 38: The reciprocating member is configured to (i) be positioned at a first dead center in response to the piston being positioned at its top dead center, and (ii) be positioned at a second dead center in response to the piston being positioned at its bottom dead center.

[0045] In a reciprocating tool including at least 1 to 10 and 35 to 38, the maximum pressure of the compressed gas is applied to the reciprocating member, causing the reciprocating member to move from the first dead center to the second dead center. Additionally, the reciprocating member moving from the second dead center to the first dead center can be decelerated by the pressure of the compressed gas.

[0046] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-38: Feature 39: The transmission device includes a cam, (i) having an outer periphery with a plurality of pins arranged in a circumferential direction of the cam, and (ii) configured to rotate by the driving force of the electric motor; Feature 40: The reciprocating member (i) extends between a first dead point and a second dead point, (ii) includes a plurality of racks in its extending direction, and (iii) is configured to be driven from the second dead point to the first dead point by the plurality of racks engaging with each of the plurality of pins.

[0047] In a reciprocating tool having at least Features 1 to 10, 39, and 40, the reciprocating member can be moved by a cam from at least the second dead center to the first dead center. Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-40: Feature 41: A position detector configured to output a position detection signal to a control circuit each time the reciprocating member reaches a predetermined position (or a predetermined phase) in at least one reciprocating motion of the reciprocating member; and Feature 42: The control circuit is configured to control the drive circuit to stop driving the electric motor in response to the control circuit receiving the position detection signal.

[0048] In a reciprocating tool having at least the features 1 to 10, 41, and 42, the reciprocating member can be stopped at a predetermined position. Some embodiments may include, in addition to or instead of at least one of features 1-42: Feature 43: The predetermined position corresponds to (i) a stop position where the reciprocating member is stopped, and / or (ii) a standby position where the reciprocating member is standby for at least one next reciprocating motion of the reciprocating member.

[0049] In a reciprocating tool having at least the features 1 to 10 and 41 to 43, the reciprocating member can be stopped at a stop position and / or a standby position. Some embodiments may include, in addition to or instead of at least one of features 1-43: Feature 44: A signal blocking circuit configured to block an electrical signal output from the control circuit from the switch element in response to the first manual switch and the switch element being in their respective off states.

[0050] In a reciprocating tool having at least features 1 to 10 and 44, even if an electrical signal is erroneously output from the control circuit when the first manual switch and the switch element are in their respective off states, the switch element can be prevented from being turned on.

[0051] Some embodiments may include at least one of the following in addition to or instead of at least one of features 1-44: Feature 45: A battery mounting portion configured to removably mount a battery pack; and Feature 46: The power source is a battery pack attached to the battery attachment section.

[0052] An embodiment may provide a method comprising at least one of the following: ·Feature 47: Connecting a first contact of the manual switch to a power source; ·Feature 48: Connecting the second contact of the manual switch to the drive circuit; Feature 49: The manual switch is configured to (i) be manually turned on or off by a user of the reciprocating tool, (ii) connect the first contact to the second contact in its on state, and (iii) disconnect the first contact from the second contact in its off state; Feature 50: The drive circuit is configured to (i) receive a current from a power source and (ii) drive the electric motor with the received current; Feature 51: The first contact and the second contact are connected via a switch element; Feature 52: The switch element is configured to (i) be turned on in response to an electric signal, (ii) establish electrical continuity between the first contact and the second contact in the on state, and (iii) interrupt electrical continuity between the first contact and the second contact in the off state; and Feature 53: In response to at least the manual switch being turned on, an electrical signal continues to be output to the switch element until the driving of the electric motor is stopped.

[0053] According to the method having at least the features 47 to 53, the power supply to the electric motor in the reciprocating tool can be maintained by a switch element that is much simpler than a mechanical mechanism.

[0054] In some embodiments, features 1-53 may be combined in any combination. In some embodiments, any of features 1-53 may be omitted. 2. Specific Exemplary Embodiments A specific exemplary embodiment is described below: This specific exemplary embodiment provides a reciprocating tool 1 as shown in FIG.

[0055] The terms "upper," "lower," "front," "rear," "left," and "right" used in the following description or drawings are used merely to facilitate easy understanding of the structure of the reciprocating tool 1 and are not intended to limit the orientation of the reciprocating tool 1. The reciprocating tool 1 can be oriented in any direction. 2-1. Overall structure of reciprocating tool 1, the reciprocating motion tool 1 in this embodiment is an electric nail gun configured to drive nails into a workpiece. Examples of nails used in the reciprocating motion tool 1 include staples, pin nails, finish nails, and brad nails. In another embodiment, the reciprocating motion tool 1 may be any other type of reciprocating motion tool, such as an electric rebar tying machine, an electric rebar cutting machine, an electric oiler, or an electric air pump.

[0056] The reciprocating tool 1 includes a housing 2. The housing 2 includes a driving assembly receptacle 3 extending from the rear end of the housing 2 to the front end (i.e., in the direction in which the nail is ejected). The reciprocating tool 1 includes an ejection section 4 in front of the driving assembly receptacle 3. The ejection section 4 includes a guide 5 configured to guide the nail ejected from the reciprocating tool 1 to the workpiece. In this embodiment, the guide 5 protrudes from inside the driving assembly receptacle 3 to the front of the reciprocating tool 1. The ejection section 4 includes a pressing member (or contact) 6 configured to be pressed against the workpiece. The pressing member 6 is disposed above the guide 5 and protrudes furthest forward of the reciprocating tool 1. The ejection section 4 includes a link mechanism 7 connected to the pressing member 6.

[0057] The housing 2 has a grip 8 extending downward from approximately the center of the driving assembly receiving portion 3. The grip 8 is configured to be held with one hand of a user of the reciprocating tool 1. The grip 8 has a trigger 9 on its upper front side. The trigger 9 is configured to be pulled by a finger (e.g., index finger) of the user.

[0058] The housing 2 includes a motor housing 10 extending downward from the front of the driving assembly housing 3. The housing 2 includes a battery attachment section 11 extending from the lower end of the motor housing 10 to the lower end of the grip 8. The battery attachment section 11 is configured so that a battery pack 12 can be detachably attached to the battery attachment section 11.

[0059] The reciprocating tool 1 includes a magazine 13 on the left side of the housing 2, the magazine 13 extending from the bottom of the guide 5 to the bottom end of the reciprocating tool 1. The magazine 13 is configured to feed one or more nails stored therein one by one into the guide 5. In this embodiment, the magazine 13 is inclined backward.

[0060] As shown in FIG. 2, the driving assembly housing 3 houses a driving assembly 14 configured to drive nails. The driving assembly 14 includes a cylinder 15 extending from the rear end of the driving assembly housing 3 to a generally central portion thereof. The cylinder 15 contains compressed gas therein. In this embodiment, the compressed gas is compressed dry air. In other embodiments, the compressed gas may be compressed inert gas, such as compressed nitrogen gas or compressed noble gas.

[0061] The cylinder 15 has a piston 16 therein. The piston 16 is configured to be able to move between the rear end and the front end of the cylinder 15 while sealing the cylinder 15. The driving assembly 14 has a bumper 17 at the front end of the cylinder 15. The bumper 17 is configured to receive the piston 16 when it reaches the front end of the cylinder 15 and stop the piston 16.

[0062] The driving assembly 14 includes a reciprocating member (or driver) 18 that passes through a bumper 17 and is connected to the piston 16. The reciprocating member 18 extends from the piston 16 toward the tip of the guide 5. The reciprocating member 18 is configured to move toward the tip of the guide 5 by pressure applied to the piston 16 by compressed gas. In other words, the piston 16 urges the reciprocating member 18 toward the tip of the guide 5 by the compressed gas. In this embodiment, the reciprocating member 18 has a length such that (i) the tip of the reciprocating member 18 reaches the tip of the guide 5 when the piston 16 reaches the front end of the cylinder 15 (i.e., the bottom dead center of the piston 16), and (ii) the tip of the reciprocating member 18 retracts into the driving assembly housing 3 when the piston 16 reaches the rear end of the cylinder 15 (i.e., the top dead center of the piston 16).

[0063] The link mechanism 7 of the injection unit 4 includes a spring 19 in the driving assembly housing 3. The link mechanism 7 is configured to urge the pressing member 6 forward by the spring 19, and to move the pressing member 6 toward the rear of the reciprocating tool 1 in response to the tip of the pressing member 6 being pressed against the workpiece.

[0064] The driving assembly accommodating portion 3 accommodates a contact switch 20 above the reciprocating member 18. The contact switch 20 is configured to be pressed (i.e., turned on) by the link mechanism 7 when the pressing member 6 is pressed against the workpiece.

[0065] The grip 8 houses a trigger switch 21. The trigger switch 21 is configured to be pressed (i.e., turned on) when the trigger 9 is pulled. The trigger switch 21 is configured to be turned off when the user's finger is released from the trigger 9.

[0066] The battery mounting section 11 houses a connector 22 configured to be detachably connected to the battery pack 12 mounted on the battery mounting section 11. The battery mounting section 11 houses a controller 23 above the connector 22.

[0067] The motor housing 10 houses an electric motor 24 in its lower portion. In this embodiment, the electric motor 24 is a three-phase brushless DC motor. In other embodiments, the electric motor 24 may be a one-phase brushless DC motor, a two-phase brushless DC motor, a four or more phase brushless DC motor, a brushed DC motor, an AC motor, or a stepping motor.

[0068] The motor accommodating section 10 accommodates a transmission device 25 above the electric motor 24. The transmission device 25 is connected to a rotor 26 of the electric motor 24 and is configured to (i) transmit the driving force of the electric motor 24 to the reciprocating member 18.

[0069] More specifically, the transmission device 25 includes a reducer 27 that (i) has a preset reduction ratio and (ii) is configured to convert the driving force of the electric motor 24 into a reduced output and transmit it to the reciprocating member 18. Therefore, the transmission device 25 can transmit a torque proportional to the reduction ratio of the reducer to the reciprocating member 18. In this embodiment, the reducer 27 is a concentric shaft gear reducer, more specifically, a planetary gear reducer. In another embodiment, the reducer 27 may be a parallel shaft gear reducer or a right-angle shaft gear reducer, depending on the structure of the transmission device 25.

[0070] 3A, the transmission device 25 includes a cam 28 above the reducer 27. In this embodiment, the cam 28 is disk-shaped. The cam 28 includes first to ninth pins 29a to 29i arranged on its outer periphery along the circumferential direction. The cam 28 is configured to rotate upon receiving the output of the reducer 27. More specifically, the cam 28 rotates counterclockwise around the rotor 26 of the electric motor 24 when viewed from above the reciprocating tool 1.

[0071] The reciprocating member 18 is provided with first to ninth racks 30a to 30i on its right side. The first to ninth racks 30a to 30i are aligned in a row in the direction in which the reciprocating member 18 extends. The first to ninth racks 30a to 30i correspond to the first to ninth pins 29a to 29i, respectively. The first to ninth pins 29a to 29i engage with the first to ninth racks 30a to 30i, respectively, and transmit the driving force of the electric motor 24 to the reciprocating member 18.

[0072] As shown in FIG. 3B , the transmission device 25 includes a holder 31 above the cam 28. In this embodiment, the holder 31 is disk-shaped. The holder 31 is made of a non-magnetic material. The holder 31 includes a first magnet 32 ​​on its upper surface. In this embodiment, the first magnet 32 ​​is disposed on the upper surface of the holder 31 with its south pole facing radially outward from the holder 31. In another embodiment, the first magnet 32 ​​may be disposed on the upper surface of the holder 31 with its north pole facing radially outward from the holder 31.

[0073] The holder 31 has a second magnet 33 on its upper surface. In this embodiment, the second magnet 33 is arranged on the upper surface of the holder 31 so that its north pole faces radially outward from the holder 31. In another embodiment, the second magnet 33 may be arranged on the upper surface of the holder 31 so that its south pole faces radially outward from the holder 31.

[0074] The holder 31 is configured to rotate by receiving the output of the reducer 27. More specifically, the holder 31 rotates counterclockwise together with the cam 28 around the rotor 26 of the electric motor 24 when viewed from above the reciprocating tool 1.

[0075] The motor housing 10 is provided with a Hall IC 34 on its right inner wall. The Hall IC 34 faces the outer periphery of the holder 31. The Hall IC 34 is configured to (i) detect the south pole of the first magnet 32 ​​when the first magnet 32 ​​approaches the Hall IC 34, and (ii) detect the north pole of the second magnet 33 when the second magnet 33 approaches the Hall IC 34.

[0076] The housing 2 is provided with a main power switch 36 at its rear upper left side, which is configured to be pressed by a user to power the reciprocating tool 1 on or off.

[0077] The housing 2 includes a mode selection switch 37 adjacent to the main power switch 36. The mode selection switch 37 is configured to be pressed by a user to select an operating mode of the reciprocating tool 1.

[0078] The housing 2 is provided with a first indicator 38 between the main power switch 36 and the mode selection switch 37. The first indicator 38 is lit (i) when the reciprocating tool 1 is set to a single-shot mode, which will be described later, or (ii) when a malfunction occurs in the reciprocating tool 1.

[0079] The housing 2 is provided with a second indicator 39 adjacent to the first indicator 38. The second indicator 39 is lit when (i) the reciprocating tool 1 is set to a repeat mode, which will be described later, or (ii) a malfunction occurs in the reciprocating tool 1. 2-2. Mechanical operation of reciprocating tools 2-2-1. Mechanical operation of reciprocating members and cams 4A to 4D, the operation of the reciprocating member 18 and the cam 28 will be described. In many cases, when processing a workpiece, a user uses the reciprocating tool 1 with the front end of the reciprocating tool 1 facing downward, and therefore, in FIGS. 4A to 4D, the front end of the reciprocating tool 1 faces downward.

[0080] As shown in FIG. 4A, the reciprocating member 18 is normally held in a standby position. The standby position is set just before the top dead center of the reciprocating member 18. In this embodiment, the standby position is a position where the reciprocating member is stopped, and also a position where the reciprocating member waits for its next reciprocating motion. At the standby position, the first to eighth pins 29a to 29h of the cam 28 are disengaged from the first to eighth racks 30a to 30h of the reciprocating member 18, and only the ninth pin 29i of the cam 28 is engaged with the ninth rack 30i of the reciprocating member 18. At this time, the piston 16 is positioned just before its top dead center.

[0081] When the electric motor 24 is driven to rotate the cam 28 counterclockwise, the reciprocating member 18 is driven from the standby position to its top dead center, as shown in Fig. 4B. At this time, the piston 16 also reaches its top dead center.

[0082] When the reciprocating member 18 reaches its top dead center and the ninth pin 29i disengages from the ninth rack 30i, the reciprocating member 18 is driven to its bottom dead center by the compressed gas pressure applied by the piston 16, as shown in FIG. 4C. As a result, the nail fed into the guide 5 is struck by the reciprocating member 18 and driven into the workpiece. When the reciprocating member 18 reaches its bottom dead center, the piston 16 also reaches its bottom dead center. The cam 28 continues to rotate even after the ninth pin 29i disengages from the ninth rack 30i, and the first to ninth pins 29a to 29i re-engage with the first to ninth racks 30a to 30i, respectively. Then, as shown in FIG. 4D, the reciprocating member 18 returns to the standby position, and the cam 28 is stopped. 2-2-2.Mechanical operation of the holder When electric motor 24 is driven, holder 31 rotates together with cam 28 as shown in Figures 5A to 5E. Figures 5A to 5C and 5E correspond to Figures 4A to 4D, respectively. Figure 5D shows the rotational position of holder 31 when cam 28 is located between (i) the rotational position of cam 28 shown in Figure 4C and (ii) the rotational position of cam 28 shown in Figure 4D.

[0083] The Hall IC 34 includes a first Hall element 34a. In this embodiment, the first Hall element 34a is configured to detect the south pole of the first magnet 32. In another embodiment, when the first magnet 32 ​​is disposed on the upper surface of the holder 31 with its north pole facing radially outward from the holder 31, the first Hall element 34a may be configured to detect the north pole of the first magnet 32.

[0084] The Hall IC 34 includes a second Hall element 34b. In this embodiment, the second Hall element 34b is configured to detect the north pole of the second magnet 33. In another embodiment, when the second magnet 33 is disposed on the upper surface of the holder 31 with its south pole facing radially outward from the holder 31, the second Hall element 34b may be configured to detect the south pole of the second magnet 33.

[0085] The first magnet 32 ​​is disposed in front of the second magnet 33 in the rotation direction of the holder 31 (counterclockwise direction in FIGS. 5A to 5E). More specifically, as shown in FIG. 5D, the first magnet 32 ​​is arranged on the upper surface of the holder 31 so that its south pole faces the first hall element 34a when preparations to stop the cam 28 begin.

[0086] As shown in Figures 5A and 5E, the second magnet 33 is arranged on the upper surface of the holder 31 so that its north pole faces the second Hall element 34b when the reciprocating member 18 is in the standby position. 2-3. Electrical configuration of reciprocating tools As shown in FIG. 6, the electric motor 24 includes first to third coils 24a to 24c, each associated with one of the three phases (i.e., U-phase, V-phase, and W-phase) of the electric motor 24. The first to third coils 24a to 24c are configured to be sequentially excited to generate a rotating magnetic field. In this embodiment, the first to third coils 24a to 24c form a delta connection. In another embodiment, the first to third coils 24a to 24c may form a star connection (or a Y-connection). The rotor 26 (i) includes a first pole 26a and a second pole 26b, and (ii) is configured to rotate when the first pole 26a and the second pole 26b receive the rotating magnetic field generated by the first to third coils 24a to 24c.

[0087] The electric motor 24 includes a rotational position detector 24d. The rotational position detector 24d is configured to output first to third pulse signals (or square wave signals) to the controller 23 in accordance with the rotational position of the rotor 26. In this embodiment, the rotational position detector 24d is a Hall sensor. In this embodiment, each of the first to third pulse signals inverts from positive (or HIGH) to negative (or LOW) or from negative (or LOW) to positive (or HIGH) every time the rotor 26 rotates through 180 electrical degrees. The first to third pulse signals have a phase difference of 60 electrical degrees from one another. In another embodiment, the rotational position detector 24d may be configured to output one pulse signal to the controller 23 every time the rotor 26 rotates through 60 electrical degrees, instead of the first to third pulse signals. In yet another embodiment, the rotational position detector 24d may be configured to output first to third sine wave signals to the controller 23, instead of the first to third pulse signals. In this case, the controller 23 may include a waveform conversion circuit configured to convert the first to third sine wave signals into first to third pulse signals. In yet another embodiment, the rotation position detector 24d may be a pulse encoder.

[0088] The reciprocating tool 1 includes a power supply line Lp extending from the positive terminal of the battery pack 12 attached to the battery attachment section 11 to the controller 23. The reciprocating tool 1 includes a ground line Ln extending from the negative terminal of the battery pack 12 attached to the battery attachment section 11 to the controller 23. The ground line Ln is connected to the ground of the reciprocating tool 1 on the controller 23. The battery pack 12 applies its output voltage (hereinafter referred to as battery voltage) between the power supply line Lp and the ground line Ln.

[0089] The controller 23 includes a control circuit 51. In this embodiment, the control circuit 51 includes a microcomputer 51a. The microcomputer 51a includes a CPU (not shown), a ROM (not shown), a RAM (not shown), an analog-to-digital (AD) converter (not shown), an input port (not shown), and an output port (not shown). In another embodiment, the control circuit 51 may include an additional microcomputer. In yet another embodiment, the control circuit 51 may include, in addition to or instead of the microcomputer 51a, a logic circuit (or a wired logic connection) including two or more electronic components. In yet another embodiment, the control circuit 51 may include, in addition to or instead of the microcomputer 51a, an ASIC and / or an ASSP. In yet another embodiment, the control circuit 51 may include, in addition to or instead of the microcomputer 51a, a PLD on which a reconfigurable logic circuit can be configured. An example of a PLD includes an FPGA. The control circuit 51 is connected to the rotational position detector 24d. The control circuit 51 is configured to (i) receive first to third pulse signals from the rotational position detector 24d, and (ii) recognize the rotational position of the rotor 26 based on the received first to third pulse signals.

[0090] The control circuit 51 is connected to the main power switch 36. The main power switch 36 has (i) a first contact connected to the ground of the reciprocating tool 1 and (ii) a second contact connected to the control circuit 51. Therefore, the main power switch 36 is configured to output a first negative logic signal to the control circuit 51 in response to the main power switch 36 being pressed (i.e., turned on). The control circuit 51 is configured to recognize that the main power switch 36 is turned on based on the control circuit 51 receiving the first negative logic signal from the main power switch 36.

[0091] The control circuit 51 is connected to the mode selection switch 37. The mode selection switch 37 has (i) a first contact connected to the ground of the reciprocating tool 1 and (ii) a second contact connected to the control circuit 51. Therefore, the mode selection switch 37 is configured to output a second negative logic signal to the control circuit 51 in response to the mode selection switch 37 being pressed (i.e., turned on). The control circuit 51 is configured to recognize that the mode selection switch 37 is turned on based on the second negative logic signal received from the mode selection switch 37.

[0092] The control circuit 51 is connected to the contact switch 20. The contact switch 20 has (i) a first contact connected to the ground of the reciprocating tool 1 and (ii) a second contact connected to the control circuit 51. Therefore, the contact switch 20 is configured to output a third negative logic signal to the control circuit 51 in response to the contact switch 20 being pressed (i.e., turned on) by the pressing member 6 being pressed against the workpiece. The control circuit 51 is configured to recognize that the contact switch 20 is turned on based on the fact that the control circuit 51 receives the third negative logic signal from the contact switch 20.

[0093] The control circuit 51 is connected to the first Hall element 34a. The first Hall element 34a is configured to output a first position detection signal to the control circuit 51 in response to the first Hall element 34a detecting the south pole of the first magnet 32. In this embodiment, the first position detection signal is a negative logic signal. In another embodiment, the first position detection signal may be a positive logic signal.

[0094] The control circuit 51 is connected to the second Hall element 34b. The second Hall element 34b is configured to output a second position detection signal to the control circuit 51 in response to the second Hall element 34b detecting the north pole of the second magnet 33. In this embodiment, the second position detection signal is a negative logic signal. In another embodiment, the second position detection signal may be a positive logic signal.

[0095] The control circuit 51 is configured to (i) be connected to the first indicator 38, and (ii) output a first lighting signal to the first indicator 38. The first indicator 38 is configured to light up upon receiving the first lighting signal from the control circuit 51.

[0096] The control circuit 51 is configured to (i) be connected to the second indicator 39, and (ii) output a second lighting signal to the second indicator 39. The second indicator 39 is configured to light up upon receiving the second lighting signal from the control circuit 51.

[0097] The controller 23 includes a power supply circuit 52 connected to (i) a first contact of the main power switch 36, (ii) a control circuit 51, (iii) a power supply line Lp, and (iv) ground. The main power switch 36 is configured to output a first negative logic signal to the power supply circuit 52 in addition to the control circuit 51. The control circuit 51 is configured to output a remote control (RC) signal to the power supply circuit 52. In this embodiment, the RC signal is a negative logic signal. In another embodiment, the RC signal may be a positive logic signal.

[0098] The power supply circuit 52 is configured to maintain its ON state (i) while receiving a first negative logic signal from the main power switch 36, or (ii) while receiving an RC signal from the control circuit 51. In its ON state, the power supply circuit 52 is configured to generate a fixed DC voltage (hereinafter referred to as the power supply voltage) Vc based on the battery voltage. The power supply voltage Vc generated by the power supply circuit 52 is supplied to the rotational position detector 24d, the first Hall element 34a, the second Hall element 34b, the first indicator 38, the second indicator 39, and various circuits on the controller 23 via paths not shown.

[0099] The controller 23 includes a voltage measurement circuit 53 configured to (i) measure the battery voltage on the power supply line Lp and (ii) output a battery voltage signal to the control circuit 51. The battery voltage signal is an analog signal having a voltage corresponding to the measured battery voltage.

[0100] The controller 23 includes a first latch circuit 54 connected to (i) the first contact of the contact switch 20 and (ii) the second Hall element 34b. The first latch circuit 54 is configured to (i) hold its output (POS) negative (or LOW) in response to a falling edge of the second position detection signal output from the second Hall element 34b, and (ii) reset its output to positive (or HIGH) in response to a third negative logic signal output from the contact switch 20.

[0101] The controller 23 includes a drive circuit 55 connected to a control circuit 51. The control circuit 51 is configured to output first to sixth pulse width modulation (PWM) signals to the drive circuit 55. The first to sixth PWM signals share the same cycle. The drive circuit 55 is configured to drive the electric motor 24 in accordance with the first to sixth PWM signals received from the control circuit 51.

[0102] More specifically, the drive circuit 55 includes a signal amplifier (or level shifter) 55a configured to amplify the first to sixth PWM signals received from the control circuit 51.

[0103] The drive circuit 55 includes first to sixth switches Q1 to Q6 that form a three-phase full-bridge circuit. The first to third switches Q1 to Q3 function as high-side switches of the three-phase full-bridge circuit and are connected to (i) the power supply line Lp and (ii) the first to third coils 24a to 24c. The fourth to sixth switches Q4 to Q6 function as low-side switches of the three-phase full-bridge circuit and are connected to (i) the first to third coils 24a to 24 and (ii) ground.

[0104] The first to sixth switches Q1 to Q6 are configured to receive the first to sixth PWM signals amplified by the signal amplifier 55a, respectively, and transition to their respective on or off states. In this embodiment, the first to sixth switches Q1 to Q6 are n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs). In another embodiment, at least one of the first to sixth switches Q1 to Q6 may be another type of semiconductor switch, including a junction field-effect transistor (JFET), a bipolar transistor, and an insulated gate bipolar transistor (IGBT). In yet another embodiment, each of or at least one of the first to sixth switches Q1 to Q6 may be a mechanical relay.

[0105] The controller 23 includes a first signal blocking circuit 56 configured to block the first to third PWM signals output from the control circuit 51. More specifically, the first signal blocking circuit 56 is configured to (i) be disabled while the output (POS) of the first latch circuit 54 is positive, and (ii) be enabled while the output of the first latch circuit 54 is negative. When the first signal blocking circuit 56 is disabled, the first to third PWM signals are transmitted to the drive circuit 55 via the first signal blocking circuit 56. When the first signal blocking circuit 56 is enabled, the first to third PWM signals are blocked from the drive circuit 55 by the first signal blocking circuit 56.

[0106] In this embodiment, the first signal blocking circuit 56 includes wired logic. More specifically, the first signal blocking circuit 56 includes first to third AND gates 56a to 56c. The first to third AND gates 56a to 56c are configured to (i) transmit the first to third PWM signals to the drive circuit 55 while the output of the first latch circuit 54 is positive, and (ii) block the first to third PWM signals from the drive circuit 55 by setting their respective outputs to negative (or LOW) while the output of the first latch circuit 54 is negative.

[0107] The controller 23 includes a current measurement circuit 57 (i) interconnected between the drive circuit 55 and ground, and (ii) configured to measure the magnitude of a current (hereinafter referred to as a motor current) flowing through the electric motor 24. The current measurement circuit 57 includes a shunt resistor R1. The shunt resistor R1 has (i) a first end connected to the fourth to sixth switches Q4 to Q6, and (ii) a second end connected to ground.

[0108] The current measurement circuit 57 includes a differential amplifier OP1 configured to (i) measure the magnitude of the motor current flowing through the shunt resistor R1 and (ii) output a current measurement signal. More specifically, the differential amplifier OP1 is configured to amplify the voltage across the shunt resistor R1 to generate the current measurement signal. The current measurement signal is therefore an analog signal having a voltage corresponding to the magnitude of the motor current. The differential amplifier OP1 may be configured in an open-loop configuration without a negative feedback circuit from its output to its input, or in a closed-loop configuration with such a negative feedback circuit. The control circuit 51 is configured to receive the current measurement signal.

[0109] The current measurement circuit 57 includes a comparator CP1 configured to detect when the trigger switch 21 is turned on. More specifically, the comparator CP1 is configured to (i) compare the voltage of the current measurement signal with a preset reference voltage Vref, (ii) set its output to positive (or HIGH) in response to the voltage of the current measurement signal being greater than the reference voltage Vref, and (iii) set its output to negative (or LOW) in response to the voltage of the current measurement signal being equal to or less than the reference voltage Vref. The reference voltage Vref is equal to or approximates the voltage of the current measurement signal when insufficient motor current, as described below, flows through the electric motor 24.

[0110] The controller 23 includes a second latch circuit 58 configured to hold the output (CUR) of the comparator CP1 positive (or HIGH) when the output of the comparator CP1 is positive. The second latch circuit 58 is configured to hold the output of the comparator CP1 positive for a period of time at least equal to or longer than the periods of the first to sixth PWM signals (e.g., 100 milliseconds) each time the output of the comparator CP1 transitions from negative to positive. The control circuit 51 is configured to receive the output of the second latch circuit 58.

[0111] The trigger switch 21 interconnects (i) the power supply line Lp and (ii) the first to third switches Q1 to Q3. More specifically, the trigger switch 21 has (i) a first contact connected to the power supply line Lp and (ii) a second contact connected to the first to third switches Q1 to Q3, and is configured to establish or block conduction between the power supply line Lp and the first to third switches Q1 to Q3.

[0112] The controller 23 includes a seventh switch Q7 connected to (i) the first contact and (ii) the second contact of the trigger switch 21. The seventh switch Q7 is configured to (i) establish electrical continuity between the first and second contacts of the trigger switch 21 in its on state, and (ii) disconnect the first and second contacts of the trigger switch 21 in its off state. Therefore, the seventh switch Q7 is configured to (i) connect the power supply line Lp to the first to third switches Q1 to Q3 via the seventh switch Q7 while the trigger switch 21 is in its off state and the seventh switch Q7 is in its on state, and (ii) disconnect the power supply line Lp from the first to third switches Q1 to Q3 while the trigger switch 21 is in its off state and the seventh switch Q7 is also in its off state. In this embodiment, the seventh switch Q7 is an n-channel MOSFET. In other embodiments, the seventh switch Q7 may be other types of semiconductor switches, including JFETs, bipolar transistors, IGBTs, and SSRs, and in yet other embodiments, the seventh switch Q7 may be a mechanical relay.

[0113] The control circuit 51 is configured to output (i) a switch-on signal for turning on the seventh switch Q7, and (ii) a switch-off signal for turning off the seventh switch Q7. In this embodiment, the switch-on signal is a positive logic signal, and the switch-off signal is a negative logic signal. In another embodiment, the switch-on signal may be a negative logic signal, and the switch-off signal may be a positive logic signal.

[0114] The controller 23 includes a second signal blocking circuit 59 configured to block the switch-on signal output from the control circuit 51. More specifically, the second signal blocking circuit 59 is configured to (i) be disabled while the output (CUR) of the second latch circuit 58 is positive, and (ii) be enabled while the output of the second latch circuit 58 is negative. When the second signal blocking circuit 59 is disabled, the switch-on signal is transmitted to the seventh switch Q7 via the second signal blocking circuit 59. When the second signal blocking circuit 59 is enabled, the switch-on signal is blocked from the seventh switch Q7 by the second signal blocking circuit 59.

[0115] In this embodiment, the second signal blocking circuit 59 includes wired logic. More specifically, the second signal blocking circuit 59 includes a fourth AND gate 59a. The fourth AND gate 59a is configured to (i) transmit a switch-on signal to the seventh switch Q7 while the output of the second latch circuit 58 is positive, and (ii) set the output of the fourth AND gate 59a to negative (or LOW) to block the switch-on signal from the seventh switch Q7 while the output of the second latch circuit 58 is negative.

[0116] The controller 23 includes an electrolytic capacitor C1 configured to supply a stable motor current to the electric motor 24. The electrolytic capacitor C1 has (i) an anode connected to the first contact of the trigger switch 21 and (ii) a cathode connected to ground. In another embodiment, the electrolytic capacitor C1 may be eliminated. 2-4. Electrical operation of reciprocating tools The electrical configuration described above operates as follows.

[0117] As shown in FIG. 7, when the power supply circuit 52 is in the ON state, if the pressing member 6 is pressed against the workpiece and the contact switch 20 is turned ON, the output (POS) of the first latch circuit 54 is held positive (or HIGH), and the first signal blocking circuit 56 is disabled. The control circuit 51 recognizes the rotational position of the rotor 26 based on the first to third pulse signals received from the rotational position detector 24d. The control circuit 51 selects (i) one of the high-side switches and (ii) one of the low-side switches according to a first table stored in ROM, and outputs PWM signals corresponding to the selected switches. The first table specifies the combination of the high-side switch and the low-side switch to be selected in association with the rotational position of the rotor 26. The first table is set to select a combination of the high-side switch and the low-side switch that will cause the rotor 26 to fail to rotate. More specifically, in this embodiment, the first table is set to select (i) a combination of high-side switches and low-side switches that generates a magnetic field that attracts the first pole 26a of the rotor 26 to the coil (any of the first to third coils 24a to 24c) facing the first pole 26a, or (ii) a combination of high-side switches and low-side switches that generates a magnetic field that attracts the second pole 26b to the coil (any of the first to third coils 24a to 24c) facing the second pole 26b of the rotor 26.

[0118] Each of the corresponding PWM signals has an initial duty ratio that is greater than zero but insufficient (e.g., 10%) to start the electric motor 24. Such an initial duty ratio causes the selected high-side switch and the selected low-side switch to supply insufficient motor current to the corresponding one of the first to third coils 24a to 24c. The rotor 26 is configured not to rotate due to the insufficient motor current.

[0119] When the trigger switch 21 is turned on and insufficient motor current flows, the output (CUR) of the second latch circuit 58 is held positive (or HIGH), disabling the second signal blocking circuit 59. When the control circuit 51 recognizes that the trigger switch 21 is turned on based on the positive output of the second latch circuit 58, it transmits a switch-on signal to the seventh switch Q7, turning on the seventh switch Q7. The control circuit 51 then performs a soft start. During the soft start, the control circuit 51 selects (i) one of the high-side switches and (ii) one of the low-side switches according to a second table stored in ROM and outputs PWM signals corresponding to the selected switches. The second table specifies the combination of the high-side switch and the low-side switch to be selected in association with the rotational position of the rotor 26. The second table is configured to select a combination of the high-side switch and the low-side switch that contributes to rotating the rotor 26. During the soft start, the control circuit 51 gradually increases the duty ratio of each of the corresponding PWM signals.

[0120] When the soft start is completed, the control circuit 51 sets the duty ratio of the PWM signal corresponding to the selected high-side switch and the selected low-side switch to 100%.

[0121] When the first Hall element 34a detects that the reciprocating member 18 has reached the stop preparation position, the control circuit 51 starts preparations to stop the electric motor 24. Specifically, the control circuit 51 calculates the remaining drive time of the electric motor 24. When the calculated remaining drive time has elapsed, the control circuit 51 sets the duty ratios of all of the first to sixth PWM signals to 0% and causes the electric motor 24 to transition to a free-run state.

[0122] Subsequently, when the second Hall element 34b detects that the reciprocating member 18 has reached the standby position, (i) the output (POS) of the first latch circuit 54 is reset to negative (or LOW), (ii) the first signal cut-off circuit 56 is enabled, and (iii) the first to third PWM signals are cut off from the first to third switches Q1 to Q3 by the first signal cut-off circuit 56. Almost simultaneously, the control circuit 51 outputs PWM signals having a predetermined duty ratio (for example, 100%) to at least two of the fourth to sixth switches Q4 to Q6 so as to generate short-circuit braking (or regenerative braking) in the electric motor 24. This generates short-circuit braking in the electric motor 24, and the electric motor 24 stops.

[0123] When the control circuit 51 recognizes that the electric motor 24 has stopped based on the first to third pulse signals, a switch-off signal is transmitted from the control circuit 51 to the seventh switch Q7, turning off the seventh switch Q7. 2-5. Operation mode of reciprocating tools As described above, the reciprocating tool 1 is configured to be switched between the single-shot mode and the continuous-shot mode. The operation of the reciprocating tool 1 in the single-shot mode and the continuous-shot mode will be outlined below.

[0124] In the single shot mode, when the trigger 9 is pulled with the pressing member 6 pressed against the workpiece, the reciprocating tool 1 drives one nail into the workpiece. In the single shot mode, the reciprocating tool 1 does not drive a nail when the trigger 9 is pulled and the pressing member 6 is pressed against the workpiece.

[0125] In the continuous firing mode, the reciprocating tool 1 drives one nail into the workpiece each time the pressing member 6 is pressed against the workpiece with the trigger 9 pulled. 2-6. Processing performed by the control circuit The processing executed by the control circuit 51 (more specifically, the microcomputer 51a) will be described in detail below. 2-6-1.Main routine During its operation, the control circuit 51 repeatedly executes a main routine shown in FIG.

[0126] 8, the control circuit 51 first waits until a preset time base has elapsed in S110 (S110: NO). When the time base has elapsed (S110: YES), the control circuit 51 proceeds sequentially from S120 to S170.

[0127] In S120, the control circuit 51 executes AD conversion processing, in which the control circuit 51 converts the battery voltage signal and the current measurement signal into respective digital values, and stores the respective digital values ​​in the RAM.

[0128] In S130, the control circuit 51 executes a switch determination process. In the switch determination process, the control circuit 51 stores in RAM the logic (positive or negative, or HIGH or LOW, or 1 or 0) of the voltages received from the main power switch 36, the mode selection switch 37, the contact switch 20, the first Hall element 34a, the second Hall element 34b, and the second latch circuit 58.

[0129] In S140, the control circuit 51 executes a standby determination process, in which the control circuit 51 determines whether or not to transition the reciprocating tool 1 to a standby state.

[0130] In S150, the control circuit 51 executes a malfunction determination process. In the malfunction determination process, the control circuit 51 determines whether an error flag is set. The error flag is (i) set when a malfunction has occurred, and (ii) cleared when no malfunction has occurred. If the error flag is set, the control circuit 51 executes a predetermined operation corresponding to the malfunction.

[0131] In S160, the control circuit 51 executes a motor control process, the details of which will be described later. In S170, the control circuit 51 executes a display process. In the display process, the control circuit 51 lights up the first indicator 38 or the second indicator 39 depending on the set operation mode. More specifically, when the reciprocating tool 1 is set to the single-shot mode, the control circuit 51 outputs a first lighting signal to the first indicator 38. When the reciprocating tool 1 is set to the continuous-shot mode, the control circuit 51 outputs a second lighting signal to the second indicator 39. In addition, when an error flag is set, the control circuit 51 outputs the first lighting signal and the second lighting signal to the first indicator 38 and the second indicator 39, respectively. 2-6-2.Interrupt processing In addition to the above-described main routine, the control circuit 51 executes an interrupt process (not shown). In this interrupt process, the control circuit 51 stores the logic (positive or negative, or HIGH or LOW, or 1 or 0) of the voltages of the first to third pulse signals in RAM. In this embodiment, the control circuit 51 periodically and repeatedly executes the interrupt process. In another embodiment, the control circuit 51 may execute the interrupt process in response to the edges or voltage levels of the first to third pulse signals or other signals. 2-6-3.Motor control processing As shown in FIG. 9, in the motor control process, first in S310, the control circuit 51 determines whether or not the contact switch 20 is turned on based on the logic of the voltage of the contact switch 20 stored in the RAM.

[0132] If the contact switch 20 is turned off (S310: NO), the control circuit 51 immediately ends the motor control process. If the contact switch 20 is turned on (S310: YES), the control circuit 51 proceeds to S320. In S320, the control circuit 51 outputs corresponding PWM signals to the selected high-side switch and the selected low-side switch (i.e., the combination of the high-side switch and the low-side switch that fails to rotate the rotor 26). The corresponding PWM signals have the initial duty ratio described above.

[0133] In the next step S330, the control circuit 51 determines whether a first predetermined time (for example, 5 seconds) has elapsed since the start of output of the corresponding PWM signal. The first predetermined time is set to prevent a nail from being accidentally ejected when the pressing member 6 is held in a state pressed against an object against the user's intention. If the first predetermined time has elapsed (S330: YES), the control circuit 51 proceeds to step S340, where it stops outputting the corresponding PWM signal and ends the motor control process.

[0134] If the first predetermined time has not elapsed (S330: NO), the control circuit 51 proceeds to S350 and determines whether the trigger switch 21 is on or not based on the logic of the output of the second latch circuit 58 stored in RAM. If the trigger switch 21 is off (S350: NO), the control circuit 51 immediately ends the motor control process.

[0135] If the trigger switch 21 is turned on (S350: YES), the control circuit 51 proceeds to S360 and determines whether the reciprocating tool 1 is set to the continuous mode. More specifically, the control circuit 51 determines whether the continuous mode flag is set. When the control circuit 51 is started, the continuous mode flag is cleared. In the reciprocating tool 1, the operating mode of the reciprocating tool 1 is switched between the single mode and the continuous mode every time the user presses the mode selection switch 37. Therefore, the control circuit 51 sets or clears the continuous mode flag based on the logic of the voltage of the mode selection switch 37 stored in the RAM.

[0136] If the reciprocating tool 1 is set to the continuous firing mode (S360: YES), the control circuit 51 proceeds to S370 and sets a driving permission flag. The driving permission flag indicates that driving a nail is permitted. In the following S380, the control circuit 51 outputs a switch-on signal to the seventh switch Q7 to turn on the seventh switch Q7, and proceeds to S410.

[0137] If the reciprocating tool 1 is set to the single-shot mode (S360: NO), the control circuit 51 proceeds to S390 and determines whether a second predetermined time (e.g., 50 milliseconds) has elapsed. The second predetermined time is set to prevent the reciprocating tool 1 from driving a nail when an operation prohibited in the single-shot mode, such as pressing the pressing member 6 against a workpiece while the trigger 9 is pulled, is performed. If the second predetermined time has elapsed (S390: YES), the control circuit 51 proceeds to S370.

[0138] If the second predetermined time has not elapsed (S390: NO), the control circuit 51 proceeds to S400 and clears the driving permission flag. In the following step S410, the control circuit 51 executes a drive process.

[0139] In the drive process, if the driving permission flag is set, the control circuit 51 executes the soft start described above. When the soft start is completed, the control circuit 51 sets the duty ratio of the PWM signal output to the selected high-side switch and the selected low-side switch (i.e., the high-side switch and the low-side switch that contribute to rotating the rotor 26) to 100%.

[0140] If the drive permission flag is cleared, the control circuit 51 immediately ends the drive process. In the following step S420, the control circuit 51 executes a stop process.

[0141] In the stop process, the control circuit 51 clears the motor stop flag. The motor stop flag indicates that the electric motor 24 is stopped. Next, based on the logic of the voltage of the first Hall element 34a stored in the RAM, it is determined whether the reciprocating member 18 is located in the stop preparation position. If the reciprocating member 18 is located in the stop preparation position, the control circuit 51 calculates the remaining drive time of the electric motor 24. When the calculated remaining drive time has elapsed, the control circuit 51 sets the duty ratios of all of the first to sixth PWM signals to 0% and causes the electric motor 24 to transition to a free-run state.

[0142] Next, the control circuit 51 determines whether the reciprocating member 18 is located at the standby position based on the logic of the voltage of the second Hall element 34b stored in the RAM. If the reciprocating member 18 is located at the standby position, the control circuit 51 outputs PWM signals having a predetermined duty ratio (for example, 100%) to at least two of the fourth to sixth switches Q4 to Q6 so as to generate short-circuit braking in the electric motor 24.

[0143] Next, the control circuit 51 determines whether or not the electric motor 24 is stopped based on the logic of the voltages of the first to third pulse signals stored in the RAM up to that point. If the electric motor 24 is stopped, the control circuit 51 sets a motor stop flag.

[0144] When this stopping process is completed, the control circuit 51 proceeds to S430 and determines whether or not the electric motor 24 is stopped. More specifically, the control circuit 51 determines whether or not a motor stop flag is set.

[0145] If the electric motor 24 is not stopped (i.e., the motor stop flag is cleared) (S430: NO), the control circuit 51 proceeds to S440. In S440, the control circuit 51 outputs a switch-on signal to the seventh switch Q7 to turn on the seventh switch Q7. In other words, the control circuit 51 continues to output the switch-on signal to the seventh switch Q7 to maintain the seventh switch Q7 in its on state.

[0146] If the electric motor 24 is stopped (i.e., the motor stop flag is set) (S430: YES), the control circuit 51 proceeds to S450. In S450, the control circuit 51 outputs a switch-off signal to the seventh switch Q7 to turn off the seventh switch Q7. 2-7. Technical Effects of the Embodiments In the reciprocating tool 1 configured as described above, even if the trigger switch 21 is turned off while the electric motor 24 is being driven, the seventh switch Q7 can maintain the power supply to the electric motor 24.

[0147] In addition, in the reciprocating tool 1, the control circuit 51 can detect that the trigger switch 21 has been turned on based on the motor current without the drive circuit 55 starting the electric motor 24, and output a switch-on signal to the seventh switch Q7.

[0148] Furthermore, in the reciprocating tool 1, when the pressing member 6 is not pressed against the workpiece, that is, when the user is not processing the workpiece, the electric motor 24 can be prevented from being started erroneously.

[0149] Furthermore, in the reciprocating tool 1, a PWM signal having an initial duty ratio is output in response to the contact switch 20 being turned on, so that it is possible to prevent the trigger switch 21 from being detected as being turned on before the contact switch 20 is turned on.

[0150] Furthermore, in the reciprocating tool 1, while the reciprocating tool 1 is set to the single shot mode, even if the trigger switch 21 is turned on within a second predetermined time after the contact switch 20 is turned on, the electric motor 24 can be prevented from being driven.

[0151] Furthermore, in the reciprocating tool 1, even if a switch-on signal is erroneously output from the control circuit 51 when the trigger switch 21 and the seventh switch Q7 are in their respective off states, the second signal blocking circuit 59 can prevent the seventh switch Q7 from being turned on. 2-8. Terminology In this embodiment, the top dead center of the reciprocating member 18 corresponds to an example of a first dead center in the general description of the embodiment, and the bottom dead center of the reciprocating member 18 corresponds to an example of a second dead center in the general description of the embodiment. The trigger switch 21 corresponds to an example of a first manual switch in the general description of the embodiment, and the seventh switch Q7 corresponds to an example of a switch element in the general description of the embodiment. The switch-on signal corresponds to an example of an electrical signal in the general description of the embodiment, and the combination of the current measurement circuit 57 and the second latch circuit 58 corresponds to an example of a physical quantity detection circuit in the general description of the embodiment. The contact switch 20 corresponds to an example of a second manual switch in the general description of the embodiment, and the single-shot mode corresponds to an example of a first mode in the general description of the embodiment. The standby position corresponds to an example of a predetermined position in the general description of the embodiment, and the combination of the second magnet 33 and the second Hall element 34b corresponds to an example of a position detector in the general description of the embodiment. The second position detection signal corresponds to an example of a position detection signal in the general description of the embodiment, and the second signal blocking circuit 59 corresponds to an example of a signal blocking circuit in the general description of the embodiment. 2-9. Variations The present disclosure is not limited to the above-described embodiment, and can be implemented in various modifications.

[0152] In one variation, the control circuit 51 may determine whether the trigger switch 21 is on or not based on the digital value of the battery signal stored in the RAM in S350. When the trigger switch 21 is turned on and a motor current flows, the battery voltage drops. Therefore, the control circuit 51 can determine whether the trigger switch 21 is on or not based on the battery voltage.

[0153] In one variation, in S350, the control circuit 51 may determine whether the trigger switch 21 is on or not based on the logic of the voltages of the first to third pulse signals stored in the RAM up to that point. When the trigger switch 21 is turned on and a motor current flows, the rotational position of the rotor 26 may change slightly. Therefore, the control circuit 51 can determine whether the trigger switch 21 is on or not based on the first to third pulse signals.

[0154] In one modification, the first contact of the trigger switch 21 may be connected to the fourth to sixth switches Q4 to Q6, and the second contact of the trigger switch 21 may be connected to the ground.

[0155] In some variations, the standby position of the reciprocating member 18 may be different from the position at which the reciprocating member 18 is stopped. 2-10. Supplementary Information In the above embodiments, multiple functions achieved by one component may be achieved by multiple components, and one function achieved by one component may be achieved by multiple components. Furthermore, multiple functions achieved by multiple components may be achieved by one component, and one function achieved by multiple components may be achieved by one component. Furthermore, part of the configuration of the above embodiments may be omitted. Furthermore, at least part of the configuration of one of the above embodiments may be added to or substituted for the configuration of another of the above embodiments. [Explanation of symbols]

[0156] 1... reciprocating tool, 2... housing, 3... driving assembly accommodating section, 4... injection section, 5... guide, 6... pressing member, 7... link mechanism, 8... grip, 9... trigger, 10... motor accommodating section, 11... battery mounting section, 12... battery pack, 13... magazine, 14... driving assembly, 15... cylinder, 16... piston, 17... bumper, 18... reciprocating member, 19... spring, 20... contact switch, 21... trigger switch, 22... connector, 23... controller, 24... electric motor, 24a to 24c... first to third coils, 24d... rotational position detector, 25... transmission device, 26... rotor, 26a... first pole, 26b... second pole, 27... reducer, 28... cam, 29a to 29i... first to ninth pins, 30a to 30i... first to ninth racks , 31...holder, 32...first magnet, 33...second magnet, 34...Hall IC, 34a...first Hall element, 34b...second Hall element, 36...main power switch, 37...mode selection switch, 38...first indicator, 39...second indicator, 51...control circuit, 52...power supply circuit, 53...voltage measurement circuit, 54...first latch circuit, 55...drive circuit, 55a...signal amplifier, 56...first signal blocking circuit, 56a to 56c...first to third AND gates, 57...current measurement circuit, 58...second latch circuit, 59...second signal blocking circuit, 59a...fourth AND gate, C1...electrolytic capacitor, CP1...comparator, Ln...ground line, Lp...power supply line, OP1...differential amplifier, Q1 to Q7...first to seventh switches, R1...shunt resistor.

Claims

1. A reciprocating tool, a reciprocating member configured to reciprocate between a first dead center and a second dead center; an electric motor configured to generate a driving force; a transmission device configured to transmit the driving force of the electric motor to the reciprocating member at least during a stroke of the reciprocating member from the second dead center to the first dead center; a drive circuit configured to (i) receive current from a power source and (ii) drive the electric motor with the received current; a first manual switch including (i) a first contact and a second contact; and (ii) a first manual switch configured to be manually turned on or off by a user of the reciprocating tool, the first contact being connected to the power source and the second contact being connected to the drive circuit, the first manual switch configured to (i) connect the first contact to the second contact in its on state, and (ii) disconnect the first contact from the second contact in its off state; a switch element configured to (i) be turned on in response to an electric signal, (ii) establish electrical continuity between the first contact and the second contact in the on state, and (iii) interrupt electrical continuity between the first contact and the second contact in the off state; a control circuit configured to continue outputting the electric signal to the switch element in response to at least the first manual switch being turned on until the driving of the electric motor is stopped; A reciprocating tool comprising:

2. The reciprocating tool according to claim 1, further comprising: a physical quantity detection circuit configured to detect a physical quantity associated with the first manual switch being turned on; The control circuit is configured to continue outputting the electrical signal to the switch element in response to the physical quantity detection circuit detecting the physical quantity until driving of the electric motor is stopped.

3. The reciprocating tool according to claim 2, The physical quantity is the current flowing from the power source to the drive circuit.

4. The reciprocating tool according to claim 2 or 3, the control circuit is configured to output at least one pulse width modulated signal having a predetermined period to the drive circuit to control the drive circuit; The drive circuit is configured to drive the electric motor based on the at least one pulse width modulated signal.

5. The reciprocating tool according to claim 4, the control circuit is configured to output the at least one pulse width modulated signal having an initial duty cycle to the drive circuit before the drive circuit starts the electric motor; The initial duty ratio is greater than zero but insufficient to start the electric motor.

6. The reciprocating tool according to claim 5, the physical quantity detection circuit is configured to continue to output a predetermined logic value to the control circuit for a time period equal to or longer than the predetermined period of the at least one pulse width modulation signal in response to the physical quantity detection circuit detecting the physical quantity; The control circuit is configured to continue outputting the electrical signal to the switch element for a period from when the control circuit receives the predetermined logical value until when driving of the electric motor is stopped.

7. The reciprocating tool according to claim 5 or 6, the electric motor is a brushless DC motor having first to third coils, the drive circuit (i) forms at least a part of a full bridge circuit, and (ii) includes first to sixth semiconductor switches connected to the first to third coils; the first to third semiconductor switches are high-side switches in the full-bridge circuit, the fourth to sixth semiconductor switches are low-side switches in the full-bridge circuit, the at least one pulse-width modulated signal includes first to sixth pulse-width modulated signals corresponding to the first to sixth semiconductor switches, respectively; The control circuit, before the drive circuit starts the electric motor, selecting a combination of (i) one of the first to third semiconductor switches and (ii) one of the fourth to sixth semiconductor switches such that the drive circuit fails to start the electric motor; selecting a pair of pulse width modulation signals corresponding to the selected combination from the first to sixth pulse width modulation signals; The selected pair of pulse width modulation signals is output to the drive circuit. It is configured as follows: A reciprocating tool, wherein each of the pair of pulse width modulated signals has the initial duty ratio.

8. The reciprocating tool according to any one of claims 1 to 7, further comprising: a pressing member configured to be pressed against the workpiece by the user; a second manual switch configured to be turned on when the pressing member is pressed against the workpiece; and Equipped with The control circuit is configured to control the drive circuit to start the electric motor based on the fact that both the first manual switch and the second manual switch are turned on.

9. A reciprocating tool according to claim 8 when dependent on any one of claims 4 to 7, The control circuit is configured to start outputting the at least one pulse-width modulated signal having the initial duty ratio in response to the second manual switch being turned on.

10. A reciprocating tool according to claim 8 or 9, the reciprocating tool is configured to be selectively set to any one of a plurality of operating modes including a first mode; The control circuit is configured to stop outputting the electrical signal in response to (i) the reciprocating tool being set to the first operating mode, and (ii) the first manual switch being turned on within a predetermined time after the second manual switch being turned on.

11. A reciprocating tool according to any one of claims 1 to 10, a cylinder containing compressed gas therein; (i) a piston within the cylinder, (ii) urging the reciprocating member toward the second dead center by the compressed gas; Equipped with A reciprocating tool, wherein the reciprocating member is configured to be driven by the piston from the first dead center to the second dead center.

12. A reciprocating tool according to claim 11, The reciprocating member is configured to (i) be positioned at the first dead center in response to the piston being positioned at its top dead center, and (ii) be positioned at the second dead center in response to the piston being positioned at its bottom dead center.

13. A reciprocating tool according to any one of claims 1 to 12, The transmission device is a cam (i) having an outer periphery with a plurality of pins arranged in a circumferential direction of the cam; and (ii) a cam configured to be rotated by the driving force of the electric motor; The reciprocating member (i) extends between the first dead center and the second dead center, (ii) has a plurality of racks in its extension direction, and (iii) is configured to be driven from the second dead center to the first dead center by the plurality of racks engaging with each of the plurality of pins.

14. The reciprocating tool according to any one of claims 1 to 13, further comprising: a position detector configured to output a position detection signal to the control circuit each time the reciprocating member reaches a predetermined position in at least one reciprocating motion of the reciprocating member; The reciprocating tool, wherein the control circuit is configured to control the drive circuit to stop driving the electric motor in response to receiving the position detection signal.

15. 15. A reciprocating tool according to claim 14, A reciprocating tool, wherein the predetermined position corresponds to (i) a stop position where the reciprocating member is stopped, and / or (ii) a standby position where the reciprocating member is standby for at least one next reciprocating motion of the reciprocating member.

16. The reciprocating tool according to any one of claims 1 to 15, further comprising: a signal interruption circuit configured to interrupt the electrical signal output from the control circuit from the switch element in response to the first manual switch and the switch element being in their respective off states.

17. The reciprocating tool according to any one of claims 1 to 16, further comprising: a battery mounting section configured to removably mount a battery pack; The power source is the battery pack attached to the battery attachment portion.

18. 1. A method for maintaining energization of an electric motor in a reciprocating tool, comprising: connecting a first contact of the manual switch to a power source; connecting a second contact of the manual switch to a drive circuit, wherein the manual switch is configured to (i) be manually turned on or off by a user of the reciprocating tool, (ii) connect the first contact to the second contact in its on state, and (iii) disconnect the first contact from the second contact in its off state, and the drive circuit is configured to (i) receive current from the power source, and (ii) drive the electric motor with the received current; The first contact and the second contact are connected via a switch element, the switch element being configured to (i) be turned on in response to an electric signal, (ii) in its on state, establish conduction between the first contact and the second contact, and (iii) in its off state, interrupt conduction between the first contact and the second contact; and continuing to output the electric signal to the switch element in response to at least the manual switch being turned on until the driving of the electric motor is stopped. The method comprises:

Images