JP7649471B2 - Power tools - Google Patents

Description

The present invention relates to power tools.

Power tools generate heat as the drive unit operates, causing the temperature to rise. In order to prevent damage to parts due to high temperatures, conventionally, when the power tool becomes hot, the operator is notified that the power tool is hot and is urged to stop using the tool, or measures are taken to forcibly prohibit use of the power tool. By taking such measures, it is possible to prevent damage to parts, etc.

As an example of such a power tool, Patent Document 1 describes a power tool that is configured to notify the operator that the power tool is hot when the temperature of the power tool exceeds a first threshold, and to forcibly stop the operation of the drive unit when the temperature of the power tool exceeds a second threshold. With this power tool, the operator is notified in advance that the power tool is hot, making it possible to avoid a situation in which the operator is forced to suddenly stop working.

JP 2020-66116 A

However, in the power tool disclosed in Patent Document 1, when an operator is notified that the first threshold has been exceeded, he or she is forced to slow down or stop working.

As a solution different from that of Patent Document 1, it is possible to actively cool the power tool by connecting a fan to the motor of the power tool. However, when connecting a fan to the motor, a sufficient cooling effect cannot be obtained in a power tool whose motor operates intermittently. It is also possible to rotate the fan independently of the drive unit, but this requires an area for mounting the fan and a structure for rotating the fan independently.

The inventors of this application therefore focused on suppressing the heat generation of the power tool itself, as an approach different from the means for actively cooling the power tool. In other words, the object of the present invention is to provide a power tool that makes it possible to suppress heat generation.

This application discloses an electric power tool having a motor. The electric power tool includes a switching element for supplying a current to the motor, and a drive circuit for supplying a control signal to the switching element. The electric power tool is further configured to reduce or cut off the voltage supplied to the drive circuit based on drive information of the electric power tool.

Here, "operation information" refers to information that indicates the operating state of the power tool and is obtained by operating the power tool.

Also, "reducing the voltage supplied to the drive circuit" includes not supplying voltage to the drive circuit and supplying ground voltage to the drive circuit. The voltage includes the power supply voltage used to power the drive circuit.

"Power tool" may be a driving tool capable of driving nails, needles, pins, and other fasteners.

The "motor" may be, for example, a three-phase brushless motor consisting of a stator with three-phase windings and a rotor with a permanent magnet.

The "switching element" may be, for example, a FET (Field Emission Transistor) or other transistor.

The power tool may, for example, be equipped with a switching circuit consisting of six transistors connected in a three-phase bridge between a positive busbar and a negative busbar, and a three-phase brushless motor consisting of a stator having three-phase windings connected to the three outputs of the switching circuit, and a rotor having a permanent magnet.

The drive circuit, for example, supplies a gate signal or a base signal as a control signal to the gate or base of a transistor, which is a switching element. The control signal may be an analog signal having a voltage for generating a voltage exceeding a threshold voltage in the switching element. The drive circuit may, for example, include an amplifier circuit for generating the gate signal or the base signal.

The power tool may further include a drive power supply circuit for generating a voltage to be supplied to the drive circuit. The drive power supply circuit may include a switching element for switching between supplying and stopping the supply of voltage to the drive circuit. The switching element may be, for example, a field emission transistor (FET) or another transistor.

The power tool may further include a control circuit for supplying control instructions to the drive circuit. The control instructions may be digital signals. The control circuit may be, for example, a CPU (Central Processing Unit) with a processor, an ASIC (Application Specific Integrated Circuit), an LSI (Large Scale Integrated Circuit), or a SoC (System On Chip).

The control circuit of the power tool may be configured to be controllable to supply or not supply voltage to the drive circuit, for example, by supplying a control signal to a switching element of the drive power circuit based on drive information of the power tool to switch the switching element ON/OFF.

The power tool may be configured to separate the drive circuit from the control circuit, and to supply the control circuit voltage to the control circuit while the drive circuit voltage is not supplied to the drive circuit. As an example of such a configuration, the power tool may include a first semiconductor chip including the drive circuit, and a second semiconductor chip including the control circuit. The power tool may include a package (enclosure) that encapsulates the first semiconductor chip and the second semiconductor chip.

The power tool may be configured so that the voltage of the drive circuit is greater than the voltage of the control circuit.

The power tool operation information may include information indicating the temperature of the power tool.

The power tool may include, for example, a temperature sensor for acquiring information indicating the temperature of the second semiconductor chip as information indicating the temperature of the power tool. This temperature sensor may be further sealed by a package (enclosure) that seals the first and second semiconductor chips. In this case, the power tool includes a first semiconductor chip including a drive circuit, a second semiconductor chip including a control circuit, and a temperature sensor that acquires information indicating the temperature of the control circuit and provides it to the control circuit, and a package (enclosure) that seals the first semiconductor chip, the second semiconductor chip, and the temperature sensor.

Alternatively, the power tool may be equipped with a temperature sensor for acquiring information indicating the temperature of the motor or the switching circuit as information indicating the temperature of the power tool. This temperature sensor may be a thermistor connected to the switching circuit. The temperature sensor may be installed on a board on which a control circuit or the like is mounted, or may be installed inside the power tool body.

The drive information of the power tool may include information indicating the operating time of a drive unit provided in the power tool. Since the operating time of the drive unit is correlated with the temperature of the power tool, heat generation can also be suppressed by configuring the voltage supplied to the drive circuit to be reduced based on the information indicating the operating time of the drive unit.

Here, "drive unit" refers to the part of the power tool that drives it. If the power tool is a driving tool, the drive unit includes a motor that drives the tool. Note that the parts that are driven by the motor may be included in the drive unit.

If the power tool is a driving tool, the operating time of the drive unit may be the operating time of the motor or the operating time of the plunger driven by the motor, and more specifically, the operating time of the drive unit may be the total time it takes for the plunger, which is at the waiting point, to drive a fastener and then return to the waiting point. For example, if the average operating time of the drive unit to drive one fastener is 100 ms and 1000 fasteners have been driven since driving began, the operating time of the drive unit is 1000 x 100 ms, or 100 seconds.

The drive information of the power tool may include information indicating the number of operations per unit time of the drive unit equipped in the power tool. Since the number of operations per unit time of the drive unit is correlated with the temperature of the power tool, heat generation can also be suppressed by configuring the voltage supplied to the drive circuit to be reduced based on the information indicating the number of operations per unit time of the drive unit.

If the power tool is a driving tool, the number of operations of the drive unit per unit time may be the number of times fasteners are driven per unit time. For example, if fasteners are driven 50 times per minute, the number of operations of the drive unit per unit time is 50 times/minute.

The driving information of the power tool may include information indicating a temperature of the motor.
The driving information of the power tool may include current information of the motor.

When the power tool is in a standby state, the voltage supplied to the drive circuit may be reduced based on the drive information of the power tool.

Here, the standby state of the power tool refers to a state in which the drive unit of the power tool is not operating. If the drive unit of the power tool is equipped with a motor, the standby state of the power tool may correspond to a state in which the motor is not rotating.

For example, in the case of an electric power tool that has a trigger as an operating unit and that is operated by an operator by pulling the trigger to start the motor rotating, the electric power tool may be configured so that the standby state of the electric power tool is from when the operator pulls the trigger to start the motor rotating and then when the motor stops to when the operator next pulls the trigger.

If the power tool is a driving tool, the standby state of the power tool may be configured such that the motor starts to rotate when the operator operates the control unit (pulls the trigger), the plunger that was waiting in the standby position moves to drive the fastener, and then the plunger returns to the standby position and the motor stops, causing the power tool to transition from an operating state to a standby state. The standby state continues until the operator next pulls the trigger.

For example, if fasteners are driven 50 times per minute and the average operating time of the drive unit to drive one fastener is 100 ms, the operating time per minute is 5 seconds and the time in standby state (hereinafter sometimes referred to as "standby time") is 55 seconds.

The inventors of this application focused on the waiting state that occurs during the gaps (typically less than one second) between successive fasteners being driven, and came up with the idea of capturing this timing to reduce the voltage supplied to the drive circuit.

The power tool may include a means for detecting the standby state of the power tool. When the main driving part of the power tool is composed of a motor, the means for detecting the standby state of the power tool may be a sensor such as a Hall element for detecting the rotation speed of the motor. Alternatively, the means for detecting the standby state of the power tool may be a control circuit for controlling the motor. The control circuit may be configured to detect that the power tool has transitioned from an operating state to a standby state based on the elapse of the time required for the motor rotation to stop from the time when brake control (stop control) for stopping the rotation of the motor is started.

This application discloses a driving tool equipped with a motor. The driving tool includes a switching element for supplying a current to the motor, and a drive circuit for supplying a control signal to the switching element. The driving tool is configured to be capable of repeatedly switching between an operating state in which a drive unit operates to drive a fastener, and a standby state in which the drive unit waits, and is configured to include a time period in which a voltage is supplied to the drive circuit during the operating state, and a time period in which a reduced voltage is supplied to the drive circuit during the standby state (including a time period in which no voltage is supplied).

The driving tool may be configured to be capable of driving at least 30 fasteners per minute. In this case, the driving tool is configured to have at least 29 standby states per minute, each of which includes a period during which a reduced voltage is supplied to the drive circuit (including a period during which no voltage is supplied). Each standby period may be less than one second. The driving tool may be configured such that the period during which a reduced voltage is supplied to the drive circuit per unit time is greater than the period during which no reduced voltage is supplied to the drive circuit.

The threshold for reducing the voltage may be configurable.

The threshold value may be a value assigned to information indicating the temperature of the power tool.

The driving tool may be configured to include a time during which an unreduced voltage is supplied to the drive circuit when the drive unit is in a standby state and the temperature of the power tool is lower than a threshold value, and a time during which a reduced voltage is supplied to the drive circuit (including a time during which no voltage is supplied) when the drive unit is in a standby state and the temperature of the power tool is higher than a threshold value.

The device may further include a notification means for notifying the user that the voltage supplied to the drive circuit has been reduced or cut off. The notification means may be any means that can be perceived by the operator, and may be, for example, a visual notification means such as an LED light, or an auditory notification means such as a buzzer.

The power tool may be configured to stop operation when the temperature of the power tool reaches a predetermined value. When a threshold value is a value assigned to the information indicating the temperature of the power tool, the predetermined value may be a value greater than the threshold value.

This application discloses an electric power tool including a motor. The electric power tool includes a switching element for supplying a current to the motor, a drive circuit for supplying a control signal to the switching element, a control circuit for supplying a control command to the drive circuit, and an operation unit (trigger) configured to be operable by an operator. The electric power tool is configured to be able to execute a first operation mode in which, when the operation unit is operated in a state in which a first voltage is supplied to the control circuit and a second voltage is supplied to the drive circuit, the motor starts to rotate by the switching element, and the supply of the second voltage to the drive circuit is not stopped after the motor stops rotating, and a second operation mode in which, when the operation unit is operated in a state in which the first voltage is supplied to the control circuit and the second voltage is not supplied to the drive circuit, the second voltage is supplied to the drive circuit, the motor starts to rotate by the switching element, and the supply of the second voltage to the drive circuit is stopped after the motor stops rotating.

The first operating mode may be configured to be executable when the power tool is at a temperature lower than a first temperature, and the second operating mode may be configured to be executable when the power tool is at a second temperature higher than the first temperature.

The power tool may be a driving tool for driving fasteners, and the power tool may be configured so that a first time required from operating the operating part to driving the fastener in the first operating mode is shorter than a second time required from operating the operating part to driving the fastener in the second operating mode.
The present application discloses a power tool including a motor, the power tool including a control circuit for controlling the motor, the control circuit being configured to partially limit execution of a control process of the power tool when drive information of the power tool satisfies a preset condition and the power tool is in a standby state.

FIG. 1 is a front view of a driving tool according to one embodiment. FIG. 2 is a cross-sectional view of a driving tool according to one embodiment. FIG. 3 is a perspective view of a plunger assembly according to one embodiment. FIG. 4 is a cross-sectional view (front view) of a plunger assembly according to one embodiment. FIG. 5 is a cross-sectional view (side view) of a plunger assembly according to one embodiment. FIG. 6 is a cross-sectional view (plan view) of a plunger assembly according to one embodiment. FIG. 7 is a perspective view including a plunger and a wire according to one embodiment. FIG. 8 is a control block diagram of the driving tool according to one embodiment. FIG. 9 is a timing chart showing a power supply state of the driving tool according to the embodiment. FIG. 10 is a flowchart of a driving method using the driving tool according to one embodiment. FIG. 11 is a graph showing a change in temperature of the driving tool according to the embodiment.

The following describes an embodiment of the present invention with reference to the drawings. The following embodiment is an example for explaining the present invention, and is not intended to limit the present invention to only that embodiment.

[First embodiment]
FIG. 1 shows a front view of an electric driving tool 10 according to the first embodiment (however, a partial cross-sectional view of the magazine portion is shown), and FIG. 2 shows a cross-sectional view of the driving tool 10 seen from the same direction (however, showing the state after all fasteners F in the magazine 14 have been driven out).

This driving tool 10 is an electric nail driver that is configured to be able to drive a nail (one example of a "fastener F") by driving a plunger 32 (FIG. 2) using a motor (FIG. 2). In this specification, "up and down," "front and back," and "left and right" are based on the position of the driving tool 10 in FIG. 1 and FIG. 2. The left direction on the paper in FIG. 1 and FIG. 2 corresponds to the direction in which the fastener F is driven out, and may be called the driving direction DR1 or ejection direction DR1, etc., and the opposite right direction on the paper corresponds to the direction away from the ejection port 12A from which the fastener F is driven out, and may be called the moving away direction DR2. The directions may be expressed using the directions X1, X2, Y, and Z shown in the drawings.

This driving tool 10 includes a housing 12, a magazine 14 that stores fasteners F to be driven by the driving tool 10, a driver 34 for driving out the fasteners F, a plunger 32 to which the driver 34 is attached, a motor 20 and a gear 22 for moving the plunger 32 from the bottom dead center to the top dead center, a coil spring 36 (an example of a "biasing member" or "driving means") that applies a driving force to move the plunger 32 from the top dead center to the bottom dead center, a moving member 38 that is disposed at the extending end of the coil spring 36, a wire 40 (an example of a "string-like member") that engages with the plunger 32 and the moving member 38 to link them, and a pulley 42 (an example of a "direction changing member") around which the wire 40 is hung. Furthermore, a battery B is provided in a removable manner in the driving tool 10.

The driving tool 10 includes a housing 12 (hereinafter, the housing 12 and the part fixed to the housing 12 may be referred to as the "tool body") that houses the main components of the driving tool 10, including the plunger 32. The housing 12 includes a grip portion 12B for the operator to hold, a bridge portion 12C that connects the battery mounting portion to which the battery B is attached and the motor 20, and a nose portion 12D for driving out the fastener F. The grip portion 12B and the bridge portion 12C are each formed, for example, in a columnar shape extending in the vertical direction so that the operator can easily hold them. The front end of the housing 12 (and the front end of the driving tool 10) includes a nose portion 12D in which an ejection port 12A for ejecting the fastener F to the left of the paper is formed. A contact arm 12D1 may be attached to the tip of the nose portion 12D. The contact arm 12D1 is provided around the ejection port 12A so that it can retract from the ejection port 12A, and functions as a safety device that allows the ejection of the fastener F only when the contact arm 12D1 is pressed against the object to be driven and the trigger 12E is pressed down.

A trigger 12E (an example of an "operating part") is provided on the housing 12. When the user presses the trigger 12E, it establishes electrical continuity between the battery B and the motor 20. The trigger 12E is exposed on a surface of the grip part 12B facing forward (the direction of ejection DR1 of the fastener F), and is biased forward (in the direction of ejection DR1) by a trigger biasing member 12F such as a spring.

Battery B is configured to be detachably attached to the lower end of grip portion 12B and bridge portion 12C. Battery B functions as a DC power source that supplies power to drive a motor, etc., and is configured to output a predetermined DC voltage (for example, 14V to 20V, 18V in this embodiment). By attaching battery B, the driving tool 10 can be carried and used. However, battery B may be configured to be stored within housing 12, or power may be supplied by means other than a battery.

The driving tool 10 includes a magazine 14 attached below the nose portion 12D. The magazine 14 is configured to be loaded with a plurality of linked fasteners F (FIG. 1). The magazine 14 includes a pusher 14A that urges the fasteners F toward the nose portion 12D. The pusher 14A is urged by a urging member (not shown) so that when the leading fastener F is driven out by the driver 34, the adjacent fasteners F are supplied to the ejection path of the nose portion 12D.

The driving tool 10 further includes a plunger assembly 30. FIG. 3 is a perspective view of the plunger assembly 30, and FIG. 4 and FIG. 5 are cross-sectional views of the plunger assembly 30 in a state where the coil spring 36 is most compressed (an example of the "first state") and in a state where the coil spring 36 is most extended (an example of the "second state"), respectively (however, if FIG. 4 is a cross-sectional view in a front view, FIG. 5 corresponds to a cross-sectional view in a left side view). FIG. 6 shows a cross-sectional view of the plunger assembly 30 in a plan view. FIG. 7 is a perspective view showing the plunger 32, a pin 38A that is a part of the moving member 38, and a wire 40 that engages with the plunger 32 and the moving member 38. The plunger assembly 30 includes the driver 34, the plunger 32, the coil spring 36, the moving member 38, the wire 40, and the pulley 42, as well as a cylinder 44 that accommodates the coil spring 36 and a pair of guide rails 46 that regulate the moving direction of the plunger 32.

The driver 34 is a member that contacts and strikes the fastener F to drive out the fastener F. As shown in these drawings, the driver 34 in this embodiment is composed of a rigid metal body formed into a long, thin rod extending in the drive direction DR1 of the fastener F. Since the fastener F is disposed on an extension line of the driver 34, when the driver 34 moves in the drive direction DR1, the front end of the driver 34 strikes the fastener F. The rear end of the driver 34 is connected to the plunger 32 and is configured to move integrally with the plunger 32.

The plunger 32 is a member that moves from the top dead center to the bottom dead center, moving together with the driver 34 to drive out the fastener F. As shown in FIG. 7, the plunger 32 has four side walls, including a first side wall 32A with which the wire 40 engages, a second side wall 32B that is connected to the first side wall 32A at a substantially right angle and engages with the guide rail 46, a third side wall 32C that is connected to the second side wall 32B at a substantially right angle and arranged substantially parallel to the first side wall 32A, with which the driver 34 engages, and a fourth side wall 32D that is connected to the third side wall 32C and the first side wall 32A at a substantially right angle, arranged substantially parallel to the second side wall 32B, and engages with the guide rail 46. A cylinder 44, which will be described later, is disposed in the hollow area surrounded by the four side walls. The outer wall surface of the first side wall portion 32A is provided with gear engagement portions 32A1, which are two convex portions provided at different heights, and the gear engagement portion 32A1 engages with a gear 22 described later, so that the plunger 32 moves from the bottom dead center to the top dead center against the elastic force (biasing force) of the coil spring 36. Here, the top dead center of the plunger 32 is set in an area on the rear end side of the tool body, and the bottom dead center is set in an area between the top dead center and the nose portion 12D. Therefore, when the plunger 32 moves from the top dead center to the bottom dead center, the plunger 32 moves in a striking direction DR1 approaching the injection port 12A, and when the plunger 32 moves from the bottom dead center to the top dead center, the plunger 32 moves in a moving away direction DR2 away from the injection port.

The first side wall 32A of the plunger 32 is further provided with a wire engaging portion 32A2. The wire engaging portion 32A2 includes a first portion 32A21 formed by protruding from the inner wall surface of the first side wall 32A in a direction toward the inside (i.e., a direction toward the third side wall 32C) and a second portion 32A22 extending from an end of the first portion 32A21 in a direction toward the top dead center. The surface of the first portion 32A21 facing the top dead center becomes a pressure receiving surface for applying a force from the wire 40 to the plunger 32 in the launch direction DR1. In addition, the second portion 32A22 restricts the wire 40 from shifting in a direction toward the third wall portion. Furthermore, by forming the first portion 32A21 to protrude in a direction approaching the third side wall portion 32C, it is possible to extend the wire 40 that engages with the pressure receiving surface of the first portion 32A21 along the inner wall surface of the first side wall portion 32A. This makes it possible to prevent the wire 40 from shifting in a direction away from the third side wall portion 32C. In addition, the wire engagement portion 32A2 is formed symmetrically with respect to a virtual plane IP1 (FIG. 6) that is parallel to a plane that approximates the second side wall portion 32B and the fourth side wall portion 32D and is equidistant from both planes. This configuration makes it possible to prevent the plunger 32 from tilting due to an imbalance of the force acting on the plunger 32 from the wire 40.

The second side wall portion 32B and the fourth side wall portion 32D are formed symmetrically with respect to the imaginary plane IP1. The second side wall portion 32B and the fourth side wall portion 32D are provided with guide rollers 32B1 and 32D1 for engaging with the guide rail 46, respectively. Two guide rollers 32B1 and 32D1 are provided on each of the top dead center side and the bottom dead center side, and by engaging each of the two guide rollers 32B1 and 32D1 with the guide rail 46, it is possible to prevent the plunger 32 from tilting during movement.

The third side wall portion 32C is provided with a driver engagement portion 32C1 that is formed symmetrically with respect to the imaginary plane IP1 and to which the rear end of the driver 34 is connected. This makes it possible to prevent the plunger 32 from tilting due to the reaction force that the plunger 32 receives when the driver 34 strikes the fastener F.

As shown in these drawings, the plunger 32 is configured so that, when the direction of movement of the plunger 32 (the direction connecting the top dead center and the bottom dead center) is used as a reference, the distance between the driver engagement portion 32C1 and the injection port 12A is smaller than the distance between the wire engagement portion 32A2 and the injection port 12A.

The cylinder 44 is a member that houses the coil spring 36 and guides the movement direction of the pin 38A that is part of the moving member 38. The cylinder 44 according to this embodiment has a cylindrical portion 44A formed in a cylindrical shape and a cap portion 44C that corresponds to a lid for the cylindrical portion 44A. The cylinder 44 penetrates the hollow area surrounded by the four side walls of the plunger 32 and is fixed to the housing 12 so that the movement direction of the plunger 32 and the central axis of the cylinder 44 are approximately parallel, and the cap portion 44C fixes the guide rail 46.

The cylinder 44 contains a coil spring 36, which is a compression spring that can expand and contract in the central axial direction of the cylinder 44, i.e., in the moving direction of the plunger 32. One end 36A of the coil spring 36 is fixed to the bottom surface of the cylinder on the injection port side (bottom dead center side of the plunger 32). A moving member 38 is disposed on the other end 36B of the coil spring 36, and tension is applied to the one end 36A side of the coil spring 36 by a wire 40. Therefore, the other end 36B of the coil spring and the moving member 38 are both configured to be movable, and when the coil spring 36 compresses from an extended state, the other end 36B of the coil spring and the moving member 38 move in the ejection direction DR1, and when the coil spring 36 expands from a compressed state and restores, the other end 36B of the coil spring and the moving member 38 move in the moving direction DR2 away from the injection port 12A. A pair of holes 44B are formed in the wall of the cylinder 44, extending parallel to the central axis, i.e., parallel to the extension direction of the coil spring 36.

The moving member 38 directly or indirectly engages with a portion of the wire 40, thereby moving the wire 40 with the extension of the other end 36B of the coil spring. The moving member 38 according to this embodiment includes an annular portion 38B disposed at the other end 36B of the coil spring, and a pin 38A fixed to the annular portion 38B and with which both ends of the wire 40 are engaged. In this embodiment, a pair of holes 44B formed in the wall of the cylinder 44 are parallel to two planes that approximate the first side wall portion 32A and the third side wall portion 32C of the plunger 32, and are formed so as to intersect with an imaginary plane IP2 (FIG. 6) passing through the central axis of the cylinder 44 and the coil spring 36. In addition, both ends of the pin 38A engage with the pair of holes 44B so that the extension direction of the pin 38A is approximately parallel to this imaginary plane. Therefore, even if the moving member 38 including the pin 38A moves in the central axis direction of the cylinder 44 as the coil spring 36 expands or compresses, it is possible to prevent the pin 38A from twisting in the circumferential direction of the cylinder 44.

The wire 40 is a member that is attached to the moving member 38 and the plunger 32 to link the moving member 38 and the plunger 32. In this embodiment, the wire 40 is formed into a ring shape at one end by connecting one end of the wire 40 to a part spaced from the end of the wire 40, and the pin 38A engages with the wire 40 by penetrating this ring-shaped part. The wire 40 that engages with the pin 38A passes through a hole in the annular part 38B of the moving member 38 and extends in the thrust direction DR1 along the central axis of the coil spring 36, passes through a hole formed in the bottom surface of the cylinder 44, and then changes direction by being wrapped around the pulley 42, extends in the separation direction DR2, and engages with the pressure-receiving surface of the wire engagement part 32A2 of the plunger 32. The wire 40 then extends in the thrust direction DR1, changes direction by being wrapped around the pulley 42, and extends in the separation direction DR2 along the central axis of the coil spring 36. At the other end, the wire 40 is formed into a loop by connecting the other end of the wire 40 to a portion spaced from the end of the wire 40, and the pin 38A is engaged with the wire 40 by passing through this loop-shaped portion. Therefore, both ends of the wire 40 are engaged with the pin 38A, and the middle portion of the wire 40 is engaged with the plunger 32.

That is, the wire 40 includes a first portion 40A including one end that engages with the moving member 38, a second portion 40B including a portion connected to the first portion 40A and extending in the launch direction DR1, a third portion 40C including a portion connected to the second portion 40B and extending approximately in the receding direction, a fourth portion 40D that connects to the third portion 40C and engages with the plunger 32, a fifth portion 40E that connects to the fourth portion 40D and includes a portion extending approximately in the launch direction DR1, a sixth portion 40F that connects to the fifth portion 40E and includes a portion extending in the receding direction DR2, and a seventh portion 40G that connects to the sixth portion 40F and includes the other end that engages with the moving member 38.

The drive mechanism for moving the plunger 32 from the bottom dead center to the top dead center is composed of a motor 20 and a gear 22. The motor 20 according to the present embodiment shown in FIG. 2 is composed of a three-phase DC brushless motor, and is arranged, for example, in the bridge portion 12C so that the output shaft of the motor 20 is approximately perpendicular to the launch direction DR1 and the separation direction DR2. A gear having the output shaft of the motor 20 as a rotation axis meshes with the first gear 22A constituting the gear 22, and the first gear 22A meshes with the second gear 22B constituting the gear 22. The first gear 22A is arranged in the separation direction DR2 with respect to the gear of the output shaft of the motor 20, and the second gear 22B is arranged in the separation direction DR2 with respect to the first gear 22A. The first gear 22A and the second gear 22B are each provided with a torque roller (not shown) that is parallel to the rotation axis and protrudes in a direction approaching the outer wall surface of the first side wall portion 32A of the plunger 32. The torque roller rotates around the central axis of the first gear 22A (second gear 22B) as the first gear 22A (second gear 22B) rotates. Since the central axis of the first gear 22A (second gear 22B) is parallel to the output shaft of the motor 20, the torque roller reciprocates in the striking direction DR1 and the separating direction DR2 as the first gear 22A (second gear 22B) rotates. When the plunger 32 is near the bottom dead center, the torque roller of the first gear 22A engages with one of the convex portions provided on the bottom dead center side as the gear engaging portion 32A1. Then, the torque roller moves in the separating direction DR2 as the first gear 22A rotates, and pushes up the gear engaging portion 32A1 of the plunger 32 in the separating direction DR2, making it possible to move the plunger 32 in the separating direction DR2. When the torque roller of the first gear 22A moves to the farthest position in the separation direction DR2, the torque roller of the second gear 22B engages with the other convex portion provided on the top dead center side as the gear engagement portion 32A1. As the second gear 22B rotates, the torque roller moves in the separation direction DR2, pushing the gear engagement portion 32A1 of the plunger 32 further in the separation direction DR2, so that the plunger 32 can be moved further in the separation direction DR2. When the torque roller of the second gear 22B moves to the farthest position in the separation direction DR2, the plunger 32 reaches the top dead center, and the engagement between the gear engagement portion 32A1 and the second gear 22B is released.

The driving tool 10 further includes a control unit 50 for driving the motor 20. The control unit 50 is mounted on a PCB board 24 (FIG. 2) that is disposed in the gap between the motor 20 and the battery B in the bridge portion 12C.

Figure 8 shows a functional block diagram of the driving tool 10. The motor 20, which is the object of control by the control unit 50, includes a rotor and a stator having three-phase windings (an example of a "stator winding"). The motor 20 is a three-phase brushless motor that is configured to be able to rotate a rotor having a permanent magnet by passing a three-phase AC current through the three-phase windings based on the DC power supply voltage supplied from battery B to generate a rotating magnetic field. Note that the motor 20 is not provided with a position detection sensor, such as a Hall IC, for detecting the position of the rotor of the motor 20. However, the motor 20 may be provided with a position detection sensor for detecting the position of the rotor.

The control unit 50 includes an inverter circuit 50A having switching elements for supplying three-phase AC current to the three-phase windings of the motor 20, a drive circuit 50B for supplying control signals to the switching elements of the inverter circuit 50A, a drive power supply circuit 50C for generating a power supply voltage for operating the drive circuit 50B and supplying it to the drive circuit 50B, a control circuit 50D for supplying control commands to the drive circuit 50B, a system power supply circuit 50E for generating a power supply voltage for operating the control circuit 50D and supplying it to the control circuit 50D, and a sensor 50S for acquiring drive information for the driving tool 10.

The inverter circuit 50A is composed of, for example, six switching elements each composed of power transistors such as FETs (Field Effect Transistors) or IGBTs (Insulated Gate Bipolar Transistors) connected in a three-phase bridge between a positive bus (power supply line) and a negative bus (ground line) connected to the output terminals of the battery B, and freewheel diodes connected in parallel to each of these switching elements. The three output terminals of this inverter circuit are each connected to the three-phase windings of the stator of the motor 20. Therefore, by turning the six switching elements ON/OFF, the inverter circuit 50A is configured to generate a voltage between the three-phase windings and supply a current.

The drive circuit 50B supplies a gate signal or a base signal as a control signal to the gate or base of the six power transistors, which are switching elements. The drive circuit 50B according to the present embodiment generates an analog signal having a voltage that exceeds a threshold voltage in the switching element and turns on the switching element, as a control signal, using a 12V DC voltage (an example of a "second power supply voltage") supplied from the drive power supply circuit 50C based on a control command received from the control circuit 50D, and supplies the analog signal to the switching element. The drive circuit 50B includes an amplifier circuit for generating a gate signal or a base signal. In the present embodiment, the drive circuit 50B is composed of a one-chip semiconductor substrate (semiconductor die). The one chip on which the drive circuit 50B is formed may be called a first semiconductor chip. However, this does not prevent the drive circuit 50B from being composed of a semiconductor substrate of multiple chips.

The drive power supply circuit 50C generates, for example, a DC voltage of 12 V as a power supply voltage for operating the drive circuit 50B based on the power supply voltage supplied from the battery B, and supplies it to the drive circuit 50B. The drive power supply circuit 50C includes an ON/OFF circuit 50C1 for switching between supplying and stopping the supply of the power supply voltage to the drive circuit 50B based on a control command (ON/OFF command) from the control circuit 50D. The ON/OFF circuit 50C1 includes a switching element formed of a transistor. Therefore, when the ON/OFF circuit 50C1 is ON and the switching element is conducting, the drive power supply circuit 50C supplies a power supply voltage of 12 V to the drive circuit 50B, and when the ON/OFF circuit 50C1 is OFF and the switching element is not conducting, the drive power supply circuit 50C does not supply a power supply voltage of 12 V to the drive circuit 50B.

The control circuit 50D supplies a control command to the drive circuit 50B to cause the drive circuit 50B to generate a control signal for controlling the six power transistors, which are switching elements. The control circuit 50D according to this embodiment generates a PWM (Pulse Width Modulation) signal, which is a digital signal, as a control command (drive command) based on a DC voltage of, for example, 5V or less (an example of a "first power supply voltage") supplied from the system power supply circuit 50E, and supplies it to the drive circuit 50B. Note that by configuring the drive circuit 50B and the control circuit 50D so that the first power supply voltage is smaller than the second power supply voltage, it is possible to increase the effect of suppressing heat generation.

Furthermore, the control circuit 50D generates a control signal (ON/OFF command) for controlling the switching element of the ON/OFF circuit 50C1 based on a DC voltage of, for example, 5 V supplied from the system power supply circuit 50E, and supplies it to the ON/OFF circuit 50C1.

The control circuit 50D is realized as a CPU consisting of a one-chip semiconductor substrate (semiconductor die) equipped with a volatile semiconductor memory (SRAM) for temporarily storing data such as the results of the arithmetic processing and part of the computer program for controlling the driving tool 10, including the arithmetic processing described in this embodiment and the control program for the motor 20, and a processor for executing the above-mentioned computer program and generating control commands including drive commands and ON/OFF commands. The one chip on which the CPU of the control circuit 50D is formed may be called the second semiconductor chip.

By providing the drive circuit 50B and the control circuit 50D as separate chips in this way, it is possible to easily realize a configuration in which the system power supply circuit 50E supplies power supply voltage to the control circuit 50D, while the control circuit 50D is used to stop the supply of power supply voltage from the drive power supply circuit 50C to the drive circuit 50B. However, this does not prevent the CPU from being constructed from a semiconductor substrate of multiple chips.

The driving tool 10 further includes a multi-chip package (peripheral device) having resin that seals the drive circuit 50B, the CPU of the control circuit 50D, and a plurality of chips that constitute the sensor 50S described later. That is, by sealing the drive circuit 50B and the CPU of the control circuit 50D in the same package, it is possible to provide a compact control unit 50. In addition, by adopting a configuration in which they are sealed in the same package, supplying a power supply voltage to the CPU of the control circuit 50D while supplying a reduced voltage (including not supplying a power supply voltage) to the drive circuit 50B, it is possible to suppress the heat generation of the drive circuit 50B and the transmission of this heat to the CPU of the control circuit 50D. In addition to the above, the package may include the drive power supply circuit 50C, the ON/OFF circuit 50C1, and the system power supply circuit 50E.

The control circuit 50D further includes a semiconductor memory such as a flash memory for non-transitory storage of the above-mentioned computer program and supplying it to the CPU of the control circuit 50D, and a semiconductor memory such as a DRAM that functions as a main memory.

The control circuit 50D having the above configuration is configured to supply or stop (not supply) a power supply voltage to the drive circuit 50B by supplying a control signal (or stopping the supply of a control signal) to the switching element of the ON/OFF circuit 50C1 of the drive power supply circuit 50C based on the driving information of the driving tool 10 obtained from the sensor 50S described later to switch the switching element ON/OFF. However, the control circuit 50D may be configured to be controllable to supply a voltage (e.g., 5V) lower than the power supply voltage (e.g., 12V) for operating the drive circuit 50B based on the driving information of the driving tool 10. Even if the configuration supplies a reduced voltage, it is possible to suppress heat generation caused by the drive circuit 50B.

The system power supply circuit 50E generates a DC voltage of, for example, 5V or less as a power supply voltage for operating the control circuit 50D based on the power supply voltage supplied from the battery B, and supplies it to the control circuit 50D. Note that since the drive power supply circuit 50C and the system power supply circuit 50E are both voltage generation circuits, some of the circuits may be shared, or both may be configured from a single chip.

The sensor 50S acquires information indicating the driving state of the driving tool 10, which is obtained by driving the driving tool 10, and supplies the information to the control circuit 50D. The sensor 50S in this embodiment is a temperature sensor that acquires information indicating the temperature of the driving tool 10. The temperature of the driving tool 10 rises when the driving tool 10 is continuously operated, and falls when the continuous operation is stopped, so the information indicates the driving state of the driving tool 10.

In this embodiment, the sensor 50S is composed of a temperature sensor such as a thermistor arranged close to the control circuit 50D or a DTS (Digital Thermal Sensor) incorporated in a semiconductor substrate constituting the CPU of the control circuit 50D. Therefore, the sensor 50S can accurately acquire the temperature of the CPU of the control circuit 50D. For this reason, in an electric tool in which a rise in temperature of the control circuit is a problem (for example, an electric tool in which the timing at which the CPU temperature of the control circuit reaches the rated temperature (for example, the maximum junction temperature) of the CPU when the electric tool is operated continuously may be earlier than the timing at which other parts reach the rated temperature of the parts), it is possible to accurately suppress heat generation in the electric tool. The inventors of the present application focused on the fact that the part that becomes a problem when the electric tool is operated continuously may be the CPU of the control circuit rather than the motor, and in this embodiment, a configuration in which the sensor 50S is arranged close to the control circuit 50D (for example, a configuration in which the sensor 50S is provided in the same package) was adopted. However, the present invention is not limited to this, and the sensor 50S may be a thermistor or other temperature sensor installed near the motor 20 or the switching element of the inverter circuit 50A. In this case, the sensor 50S can obtain the temperature of the motor 20 with high accuracy. With this configuration, it is possible to reduce the possibility of a layer short in the stator winding of the motor 20 or the motor 20 burning out.

In the above configuration, the control unit 50 is configured to be able to drive the driving tool 10 in at least two operating modes using the control circuit 50D. Figures 9 (A) and (B) are timing charts showing the power supply voltage (system power supply) supplied to the control circuit 50D, the power supply voltage (driver power supply) supplied to the drive circuit 50B, the operation state of the trigger 12E, and the drive state of the motor 20 in the first and second operating modes of the driving tool 10.

9(A), the first operation mode is an operation mode capable of performing continuous operation of driving multiple fasteners F while continuously supplying the power supply voltage for the control circuit operation from the system power supply circuit 50E to the control circuit 50D and continuously supplying the power supply voltage for the drive circuit operation from the drive power supply circuit 50C to the drive circuit 50B. When the control circuit 50D detects that the operator has operated the trigger 12E to drive the fastener F in the first operation mode, the control circuit 50D supplies a control command for controlling the motor 20 to the drive circuit 50B, so that the motor 20 starts to rotate (A in FIG. 9(A)), and the driving tool 10 enters an operating state. After the fastener F is driven, the motor 20 stops rotating and the driving tool 10 transitions from the operating state to the standby state, but the supply of the power supply voltage from the system power supply circuit 50E to the control circuit 50D and the supply of the power supply voltage from the drive power supply circuit 50C to the drive circuit 50B continue.

As shown in FIG. 9B, the second operation mode is an operation mode capable of performing continuous operation of driving multiple fasteners F while continuously supplying the power supply voltage for the control circuit operation from the system power supply circuit 50E to the control circuit 50D and intermittently (intermittently) supplying the power supply voltage for the drive circuit operation from the drive power supply circuit 50C to the drive circuit 50B. When the control circuit 50D detects that the operator has operated the trigger 12E to drive the fastener F in the second operation mode, the control circuit 50D supplies a control signal to the ON/OFF circuit 50C1 to control the switching element of the ON/OFF circuit 50C1 to ON. As a result, the drive power supply circuit 50C starts supplying the power supply voltage for the drive circuit operation to the drive circuit 50B (B in FIG. 9B). After that, the control circuit 50D supplies a control command for controlling the motor 20 to the drive circuit 50B, so that the motor 20 starts rotating (C in FIG. 9B), and the driving tool 10 is in an operating state. When the motor 20 stops rotating after the driving is completed and the driving tool 10 transitions from the operating state to the standby state, the control circuit 50D stops supplying the control signal for controlling the switching element of the ON/OFF circuit 50C1 to ON in order to control the switching element to OFF. As a result, the supply of power supply voltage from the system power supply circuit 50E to the control circuit 50D continues, while the supply of power supply voltage from the drive power supply circuit 50C to the drive circuit 50B stops (D in FIG. 9B). When the operator then operates the trigger 12E again to drive the fastener F, the supply of power supply voltage for the drive circuit operation from the drive power supply circuit 50C to the drive circuit 50B begins in the same manner as described above. Thereafter, the same steps are executed.

Here, as a means for the control circuit 50D to detect that the motor 20 has stopped rotating after driving and the driving tool 10 has transitioned to a standby state, the control unit 50 may be provided with a counter that starts counting from the start of brake control (stop control) to stop the rotation of the motor 20. Since the estimated time required from the start of brake control to the stop of the rotation of the motor 20 is known, the control unit 50 can accurately detect that the driving tool 10 has transitioned from an operating state to a standby state by determining whether the time required for the rotation of the motor 20 to stop has elapsed based on the count value of the counter.

Alternatively, the control unit 50 may be configured to detect that the driving tool 10 has transitioned from the operating state to the standby state based on other timing, such as counting the time required from the start of driving to the completion of driving. As yet another means, the control unit 50 may be configured to detect that the motor has stopped rotating and that the driving tool 10 has transitioned from the operating state to the standby state based on a signal obtained from a sensor such as a Hall element for detecting the rotation speed of the motor. Or, the control unit 50 may be configured to detect that the motor has stopped rotating and that the driving tool 10 has transitioned from the operating state to the standby state based on a back electromotive force generated in the stator winding, etc.

The control circuit 50D of the driving tool 10 according to this embodiment is configured to switch between the first and second operation modes based on the driving information of the driving tool 10 acquired from the sensor 50S. Specifically, the sensor 50S installed near the CPU of the control circuit 50D supplies information indicating the temperature of the driving tool 10 to the control circuit 50D, and the control circuit 50D operates the driving tool 10 in the first operation mode when the temperature of the driving tool 10 estimated based on the information acquired from the sensor 50S is less than a predetermined first threshold value, operates the driving tool 10 in the second operation mode when the temperature of the driving tool 10 estimated based on the information acquired from the sensor 50S is equal to or greater than a predetermined first threshold value and less than a predetermined second threshold value, and stops the operation of the driving tool 10 when the temperature of the driving tool 10 estimated based on the information acquired from the sensor 50S reaches the second threshold value. The temperature of the driving tool 10 compared with the first threshold value, etc. is not limited to a value indicating the actual temperature of the driving tool 10, but may be a value that varies depending on the temperature of the driving tool 10. For example, the driving tool 10 may be configured to compare the value obtained from the sensor 50S with the first threshold value, etc. without converting it into the temperature of the driving tool 10.

The following describes a driving method using the driving tool 10 according to this embodiment. Figure 10 is a flowchart showing the driving method. Figure 11 is a graph showing the temperature change of the driving tool 10 during continuous operation.

First, when the operator turns on the main power switch of the driving tool 10, the system power circuit 50E continuously supplies the control circuit 50D with a power supply voltage (system power supply) for operating the control circuit. The control circuit 50D acquires temperature information of the driving tool 10 from the sensor 50S (step S101) and determines whether the temperature of the driving tool 10 estimated based on the acquired temperature information is less than a predetermined first threshold (step S102). If the temperature of the driving tool 10 is less than the first threshold (YES), the control circuit 50D operates the driving tool 10 in the first operating mode (step S103). When the operator pulls the trigger 12E (step S104), the control circuit 50D detects that the trigger 12E has been pulled and supplies a control command (PWM signal) for controlling the motor 20 to the drive circuit 50B, and the drive circuit 50B supplies a control signal to the switching element of the inverter circuit 50A, so that the output voltage of the battery B is applied to the three-phase winding constituting the stator of the motor 20 and a current flows through the winding of each phase. The rotor of the motor 20 starts to rotate according to the rotating magnetic field generated by the current, and the driving tool 10 transitions from a standby state to an operating state. When the motor 20 starts to rotate, the torque roller provided on the second gear 22B comes into contact with the gear engagement portion 32A1 of the plunger 32, which has been waiting at a standby position between the top dead center and the bottom dead center, and pushes the plunger 32 up in the separation direction DR2. Because the plunger 32 is connected to the moving member 38 by the wire 40, the moving member 38 moves in the ejection direction DR1 while compressing the coil spring 36 in conjunction with the movement of the plunger 32 in the retraction direction DR2. When the plunger 32 reaches the top dead center, the engagement between the plunger 32 and the gear 22 is released. As a result, the coil spring 36, which was in a compressed state, expands all at once. The moving member 38 moves together with the other end of the coil spring 36 in the retraction direction DR2, which corresponds to the expansion direction of the coil spring 36. Because the moving member 38 is connected to the plunger 32 by the wire 40, the plunger 32 and the driver 34 move in the ejection direction DR1 in conjunction with the movement of the moving member 38 in the retraction direction DR2.

When the plunger 32 reaches near the bottom dead center (or immediately before reaching that position), the driver 34, which moves in the ejection direction DR1 together with the plunger 32, ejects the fastener F supplied to the nose portion 12D in the ejection direction DR1 (step S105). The fastener F is ejected from the ejection port 12A and driven into the target object.

When the plunger 32 reaches the bottom dead center, the first gear 22A, which rotates in synchronization with the rotor of the motor 20, is configured to engage with the gear engagement portion 32A1 of the plunger 32. Therefore, the plunger 32 starts to move from the bottom dead center toward the top dead center. As the plunger 32 moves toward the top dead center, the coil spring 36 is compressed.

At a predetermined timing, the control circuit 50D starts deceleration control to decelerate the rotation of the motor 20, for example, brake control as an example of deceleration control. Specifically, the control circuit 50D generates a PWM signal with a smaller duty ratio than during normal rotation and outputs it to the drive circuit 50B. The rotation speed of the rotor of the motor 20 is greatly reduced by the deceleration control by the control circuit 50D. Even if the rotation speed is reduced, the motor 20 is still rotating, so the plunger 32 continues to move gently toward the top dead center. Alternatively, as the brake control, a short brake that turns off the upper arm of the inverter circuit and turns on the lower arm, or a chopper brake that turns off the upper arm and turns on/off the lower arm by PWM control or the like may be used.

When the control circuit 50D completes the brake control, the rotor of the motor 20 stops rotating, and the plunger 32 stops at the stop position (standby position), so that the driving tool 10 transitions from an operating state to a standby state (step S106). Thereafter, as long as the temperature of the driving tool 10 is below the predetermined first threshold, steps S101 to S105 can be repeated to continuously drive fasteners F into the target object.

By performing continuous operation in the first operating mode, the temperature of the driving tool 10 increases over time, as shown by the solid line L1 in Figure 11.

The timing for supplying the power supply voltage for drive circuit operation from the drive power supply circuit 50C to the drive circuit 50B may be after the main power switch of the driving tool 10 is turned on, or it may be configured to determine whether or not the power supply voltage for drive circuit operation is not being supplied to the drive circuit 50B after step S103, and to execute a step of supplying the power supply voltage if it is determined that the power supply voltage is not being supplied (for example, when step S103 is executed for the first time after the main power switch of the driving tool 10 is turned on, it is possible that the power supply voltage for drive circuit operation is not being supplied to the drive circuit 50B).

If the temperature of the driving tool 10 is equal to or higher than the first threshold value in step S102 (NO), the control circuit 50D determines whether the temperature of the driving tool 10 is lower than a predetermined second threshold value that is higher than the first threshold value (step S107). If the temperature of the driving tool 10 is lower than the second threshold value (YES), the control circuit 50D operates the driving tool 10 in the second operation mode (step S108). The driving tool 10 is provided with a notification means for notifying the operator that the temperature of the driving tool 10 has become high and that the supply of the power supply voltage to the drive circuit 50B in the standby state is stopped or reduced. If the temperature of the driving tool 10 is equal to or higher than the first threshold value, the control circuit 50D causes the notification means to execute a notification. The notification means may be any means that can be perceived by the operator, and may be, for example, a visual notification means such as an LED light, or an auditory notification means such as a buzzer. The operator can recognize that the driving tool 10 has become too hot by the notification means, and can adjust the future work schedule based on the fact that operation will eventually stop if work continues.

When the operator pulls the trigger 12E (step S109), the control circuit 50D detects that the trigger 12E has been pulled, and if the switching element of the ON/OFF circuit 50C1 is OFF, it supplies a control signal to the ON/OFF circuit 50C1 to control the switching element of the ON/OFF circuit 50C1 to ON. As a result, the drive power supply circuit 50C starts supplying the power supply voltage for the drive circuit operation to the drive circuit 50B (step S110). The control circuit 50D then supplies a control command (PWM signal) to the drive circuit 50B to control the motor 20. After that, the operation of the driving tool 10 up to the point where the fastener F is driven in the driving direction DR1 and driven in (step S111) and the operation to stop the rotation of the motor 20 by brake control are the same as those described above, so detailed explanations will be omitted.

The control circuit 50D detects that the driving tool 10 has transitioned from an operating state to a standby state based on the elapse of the time required for the motor 20 to stop rotating from the time when the brake control for stopping the rotation of the motor 20 was started (step S112). Next, the control circuit 50D stops supplying the control signal for controlling the switching element of the ON/OFF circuit 50C1 to ON in order to control the switching element to OFF. As a result, the supply of the power supply voltage from the system power supply circuit 50E to the control circuit 50D continues, while the supply of the power supply voltage from the drive power supply circuit 50C to the drive circuit 50B is stopped (step S113). Thereafter, steps S101, S102, and steps S107 to S113 are repeated as long as the temperature of the driving tool 10 is equal to or higher than the first threshold and lower than the second threshold.

For example, assuming that the number of times fasteners are driven per minute is 50, and the average operating time of the drive unit to drive one fastener in the first operating mode is 100 ms, the time in the operating state per minute (hereinafter sometimes referred to as the "operating time") is 5 seconds, and the time in the standby state (hereinafter sometimes referred to as the "standby time") is 55 seconds. In other words, even when fasteners F are continuously driven using the driving tool 10, there is a limit to the timing at which the operator can continuously drive fasteners F into different locations, so the standby time is longer than the operating time.

In the second operating mode, the supply of power supply voltage to the drive circuit 50B is stopped during at least a portion of the standby state (e.g., 50% or more of the standby state), so that heat generation associated with the supply of power supply voltage to the drive circuit 50B can be suppressed compared to the first operating mode.

On the other hand, in the second operation mode, compared to the first operation mode, steps such as supplying power supply voltage to the drive circuit 50B and time required for current stabilization are required, so the time required from the operator operating the trigger 12E to the driving in in the second operation mode (for example, 95 ms to 105 ms) is longer by, for example, 5 ms to 15 ms than the time required from the operator operating the trigger 12E to the driving in in the first operation mode (sometimes called the response time. For example, 90 ms to 100 ms). In particular, when the DC voltage supplied from the battery B drops, the time required from the operator operating the trigger 12E to the driving in becomes longer. Therefore, the driving tool 10 is configured to execute the first operation mode when the driving tool 10 is relatively low temperature, and execute the second operation mode when the driving tool 10 is relatively high temperature. By making the time difference between the first operation mode and the second operation mode 10 ms or less, the operator's work is not significantly hindered. However, the driving tool 10 may be configured so that the operator can selectively execute the first operating mode even at high temperatures, and the driving tool 10 may be configured so that the operator can selectively execute the second operating mode even at low temperatures.

The dashed line L2 in FIG. 11 shows the temperature change of the driving tool 10 when the first operation mode is continued even after the temperature of the driving tool 10 exceeds the first threshold, and the solid line L3 shows the temperature change of the driving tool 10 when the driving tool 10 is switched to the second operation mode. As shown in the figure, while the motor 20 and the like are stopped in the standby state of the driving tool 10, it is possible to suppress the heat generation of the drive circuit 50B by stopping the power supply to the drive circuit 50B. As a result, it has become clear that it is possible to relatively suppress the temperature rise of the driving tool 10. As shown in the figure, the time from the first threshold to the second threshold when switching to the second operation mode at the first threshold is at least 1.5 times or more than the time from the first threshold to the second threshold when the first operation mode is continued. In other words, the driving tool 10 is configured to set the first threshold so that the time from the first threshold to the second threshold when switching to the second operation mode is at least 1.5 times or more than the time from the first threshold to the second threshold when the first operation mode is continued. As a result, it is possible to increase the number of times fasteners F can be continuously driven before the temperature at which the driving tool 10 must be stopped to prevent component failure is reached, and to reduce the frequency of interruptions to work.

The second threshold value is preferably set based on the temperature at which operation must be stopped to prevent component failure of the driving tool 10. For example, if the CPU of the control circuit 50D is the first of the components of the driving tool 10 to reach its rated temperature (e.g., maximum junction temperature) when the driving tool 10 is operated continuously, the driving tool 10 may be configured to install a sensor 50S near the CPU and compare the CPU temperature estimated based on information obtained from the sensor 50S with the second threshold value set as the rated temperature of the CPU.

In step S107, if the temperature of the driving tool 10 is equal to or higher than the second threshold value (NO), the control circuit 50D stops the operation of the driving tool 10 (step S114).

As described above, it is possible to provide a driving tool that can suppress heat generation. Note that the present invention is not only applicable to driving tools. In a power tool that has a motor and an inverter circuit for operating the motor and that periodically repeats tasks, and in a power tool that repeats an operating state in which the motor rotates and a standby state in which the motor does not rotate, the present invention can be applied to a power tool that is configured to reduce (including stop) the power supply voltage to a drive circuit that supplies a control signal to the inverter circuit in the standby state.

For example, when a power tool including a driving tool performs a clear erase operation (driving a fastener) at least 30 times per minute, the power tool (driving tool) according to the present invention may be configured to include a time during which a reduced power supply voltage is supplied to the drive circuit (including a time during which no power supply voltage is supplied) in at least 29 standby states per minute. Also, each standby period may be less than one second. It is preferable that the power tool (driving tool) is configured so that the time during which a reduced power supply voltage is supplied to the drive circuit per unit time (e.g., per minute) is greater than the time during which an unreduced power supply voltage is supplied to the drive circuit.

The driving tool 10 may also be provided with, for example, an operation panel into which an operator can input information. The driving tool 10 may also be configured so that an operator can set, for example, the first threshold value using the operation panel.

[Modification]
In the above embodiment, the sensor 50S acquires information indicating the temperature of the driving tool 10 as information indicating the driving state of the driving tool 10. However, the information indicating the driving state of the driving tool 10 is not limited to the temperature information of the driving tool 10.

In this modified example, the sensor 50S acquires information indicating the operating time of the drive unit of the power tool. The operating time of the drive unit is information that correlates with the temperature of the power tool. When the power tool is a driving tool, the drive unit is a motor or a plunger. When the motor stops, the plunger stops, so the operating times of the two are approximately the same. Also, the more times the fastener F is driven in, the longer the operating time of the motor or plunger increases and the higher the temperature becomes, so it is possible to use the operating time of the drive unit as information indicating the operating state of the driving tool 10.

As a means for acquiring the operating time of the drive unit, for example, the time at which the control circuit 50D supplies a control command to rotate the motor 20 may be acquired. In addition, the operating time of the drive unit may be configured to start counting when the operator turns on the main power switch, and to reach zero when the operator turns off the main power switch.

For example, if the average operating time of the drive unit to drive one fastener is 100 ms, and the first operating mode is switched to the second operating mode when approximately 1,000 fasteners have been driven continuously, the operating time of the drive unit from the start of driving to the driving of 1,000 fasteners is 1,000 x 100 ms, which is approximately 100 seconds. Therefore, it is possible to set 100 seconds as the first threshold value.

The sensor 50S may be configured to acquire information that varies depending on the operating time of the drive unit as information indicating the operating time of the drive unit. For example, the time since the main power switch was turned on may be the information indicating the operating time of the drive unit, or the sensor 50S may be configured to acquire the standby time of the drive unit.

Furthermore, the driving information of the power tool may include information indicating the number of times the drive unit of the power tool operates per unit time. As described above, in a power tool, an operating state in which the motor rotates and a standby state in which the motor does not rotate are repeated, so when driving 50 fasteners F, the number of operations is 50. As the number of times fasteners F are driven increases, the operating time of the motor or plunger increases and the temperature also rises, so it is possible to use the operating time of the drive unit as information indicating the driving state of the driving tool 10.

Here, by acquiring the number of operations per unit time (e.g., per minute) as drive information, it is possible to improve the correlation with temperature. Since the number of operations (the number of times fasteners are driven in in the case of a driving tool) is information that is easy for an operator to grasp, by configuring the power tool (driving tool) so that the operator can set the first threshold value using an input means such as an operation panel, it becomes possible to switch between the first and second operating modes in accordance with the work content of the operator. Current information when the motor is driven may also be used as drive information. For example, an integrated current value may be used instead of the operating time.

In addition, the present invention can be modified in various ways without departing from the gist of the invention. For example, a third operation mode different from the first operation mode and the second operation mode may be executable. In this case, the third operation mode may be executed after the execution of the first operation mode, and then the second operation mode may be executed. Alternatively, the third operation mode may be executed after the execution of the second operation mode. In addition, the power supply voltage of the system power supply circuit 50E may be supplied to the drive circuit 50B during standby. In addition, two or more temperature sensors may be arranged in the printed wiring board on which the motor and inverter circuit are mounted, and in the package of the CPU, and when the temperature obtained from any of the temperature sensors reaches a first threshold value set correspondingly, the second operation mode may be switched to. In addition, the present invention can be modified within the scope of the normal creative ability of a person skilled in the art. For example, the present invention can be modified as follows.

[Modification]
The power tool of the first embodiment suppresses heat generation in the drive circuit 50B by cutting off the voltage supply to the drive circuit 50B when in a standby state with the trigger OFF and not pulled.

This modification discloses an invention relating to a power tool in which the voltage supply to a part of a control circuit 50D for controlling the motor 20 is reduced or cut off when the power tool is in a standby state.
The power tool may be a driving tool 10 or the like, but is not limited thereto.

When such a power tool is in a standby state, the voltage supply to a portion of the control circuit 50D for controlling the motor 20 may be reduced or cut off, and the voltage supply to the drive circuit 50B may be reduced or cut off as described in the first embodiment. By adopting such a configuration, it is possible to realize an embodiment of this modified example with a simplified configuration.

However, such an electric power tool may be configured such that when the electric power tool is in standby state, the voltage supply to a portion of the control circuit 50D for controlling the motor 20 is reduced or cut off, while the voltage supply to the drive circuit 50B is not reduced or cut off.
In addition, when the voltage supply to a part of the control circuit 50D for controlling the motor 20 is reduced or cut off during standby, the voltage supply to the other parts of the control circuit 50D is continued. Therefore, the voltage supply to the other parts is not reduced or cut off. With this configuration, it is possible to detect when the power tool has returned from the standby state to the operating state using the other parts of the control circuit 50D.

By employing the above-described configuration, it is possible to reduce the amount of heat generated by the control circuit 50D, and therefore the amount of heat generated by the power tool.
This modified example is preferably applicable to power tools in which a decrease in response is not a major problem, and power tools that are started up from a sleep mode by a method other than a trigger operation, for example.

10. Driving tool 12. Housing 12E. Trigger 20. Motor 22. Gear 24. PCB board 32. Plunger 34. Driver 40. Wire 42. Pulley 44. Cylinder 50. Control unit 50A. Inverter circuit 50B. Drive circuit 50C. Drive power circuit 50C1. ON/OFF circuit 50D. Control circuit 50E. System power circuit 50S. Sensor

Claims (10)

A motor;
A switching element for supplying a current to the motor;
a drive circuit for supplying a control signal to the switching element;
a control circuit that supplies a control command to the drive circuit to generate the control signal;
a drive power supply circuit for generating a voltage to be supplied to the drive circuit;
A power tool comprising:
The power tool, wherein the control circuit is configured to reduce or cut off the voltage supplied from the drive power supply circuit to the drive circuit based on drive information of the power tool. The power tool according to claim 1, characterized in that the drive information of the power tool includes information indicating the temperature of the power tool. The power tool according to claim 1, characterized in that the drive information of the power tool includes information indicating the operation time of a drive unit provided in the power tool. The power tool according to claim 1, characterized in that the drive information of the power tool includes information indicating the number of operations per unit time of a drive unit provided in the power tool. The power tool according to claim 1, characterized in that the drive information of the power tool includes information indicating the temperature of the motor. The power tool according to any one of claims 1 to 5, characterized in that, when the power tool is in a standby state, the power supply voltage supplied to the drive circuit is reduced or cut off based on the drive information of the power tool. The power tool according to claim 6, characterized in that it is configured to be able to set a threshold value for the power tool's driving information that reduces or cuts off the power supply voltage. The power tool according to any one of claims 1 to 7, further comprising a notification means for notifying that the voltage supplied to the drive circuit has been reduced or cut off. The power tool according to any one of claims 1 to 8, characterized in that the power tool is configured to stop operation when the temperature of the power tool reaches a predetermined value. A motor;
A switching element for supplying a current to the motor;
a drive circuit for supplying a control signal to the switching element;
a control circuit that supplies a control command to the drive circuit to generate the control signal;
a drive power supply circuit for generating a voltage to be supplied to the drive circuit;
A power tool comprising:
The control circuit includes:
The driving information of the power tool satisfies a preset condition,
And when the power tool is in a standby state,
The control circuit is configured to partially limit the execution of its own control process;
The drive information of the power tool includes information indicating a temperature of the power tool or information indicating an operation time of a drive unit provided in the power tool,
The power tool, characterized in that the control circuit partially restricts the execution of its own control processing, including reducing or cutting off the voltage supplied by the drive power supply circuit to the drive circuit based on drive information of the power tool.

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