JP2012179664A - Electric driving machine and method for driving fastener - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric driving machine that improves efficiency and enables energy saving by reducing current consumption of a circuit in a system to charge a capacitor by boosting a voltage of a battery, thereby reducing consumption of the battery, and a method for driving a fastener.SOLUTION: When both nail detection switches 291 and 292 constituting a length detection means are turned off, a nail is determined to be long, and a target boosting voltage is set to V2. When the nail detection switch 291 is turned off and the nail detection switch 292 is turned on, the nail is determined to be short, and the target boosting voltage is set to V1 (wherein V1<V2). This is because a longer nail requires more energy. Appropriate energy can be set according to the length of the nail, thereby achieving effective use of energy of a secondary battery 3.

Description

  The present invention relates to an electric driving machine driven by a battery and a method for driving the fastener, which is suitable for driving a fastener such as a nail or a staple into a material to be driven such as wood.

  Cordless tools that move motors with charged secondary batteries have already been put into practical use. An electric double layer capacitor that is capable of charging and discharging a large current with a relatively high capacity is also known. In addition, an electric nailing machine for driving nails by a solenoid or the like is also known. Various methods have been proposed in which the voltage of the battery is transferred to the capacitor, and a nail is driven by driving a solenoid with a high-power capacitor capable of discharging a large current. For example, the output of the capacitor is increased by boosting the voltage of the battery to charge the capacitor and increasing the voltage of the capacitor.

JP-A-61-214982

  In order to boost the voltage of the battery and charge the capacitor, various circuits are required to control the current, and the current consumption of the circuit increases. Then, the battery is consumed quickly, and in the case of a secondary battery, there is a problem that the work amount per charge is reduced. Moreover, in the case of a primary battery, since the use time becomes short, it is necessary to prepare a plurality of spare primary batteries.

  The present invention has been made in view of such a situation, and its purpose is to boost the battery voltage and charge the capacitor, thereby improving the efficiency and saving energy by reducing the current consumption (electric power) of the circuit. An object of the present invention is to provide an electric driving machine and a fastener driving method capable of suppressing battery consumption.

One embodiment of the present invention is an electric driving machine. This electric driving machine
A main body and a battery for supplying power to the main body,
The main body includes a magazine for supplying a fastener to a driving preparation position, a plunger capable of driving the fastener existing in the driving preparation position by projecting toward the driving preparation position, and the plunger. Plunger urging means for urging in a direction away from the driving preparation position, a plunger driving coil for generating a magnetic force that gives the plunger a projecting output to the driving preparation position, and a supply voltage to the plunger driving coil A coil voltage generator for generating
The coil voltage generator includes a booster circuit that boosts a supply voltage from the battery, a capacitor to which an output voltage of the booster circuit is applied and provided in parallel with the plunger drive coil, and the plunger from the capacitor A coil energization switch capable of switching on / off of energization to the drive coil, and a controller for controlling at least the booster circuit;
The controller is capable of switching a boost target voltage of the boost circuit between a first target voltage and a second target voltage higher than the first target voltage.

In the electric driving machine,
A length detecting means for detecting whether or not the length of the fastener existing in the magazine is a predetermined value or more;
When the length detecting means detects that the length of the fastener is less than the predetermined value, the controller sets the boost target voltage of the booster circuit as the first target voltage, and sets the length of the fastener. When the length detecting means detects that the voltage is equal to or greater than the predetermined value, the boost target voltage of the boost circuit may be set as the second target voltage.

The length detection means includes at least a pair of light emitting elements and light receiving elements attached to the magazine, and a light shielding member extending to a length detection position in a supply path of a fastener in the magazine,
The light blocking member is pushed in a direction of exiting the supply path by a fastener having a length equal to or greater than the predetermined value present at the length detection position, and blocks light from the light emitting element toward the light receiving element. When there is no fastener having a length equal to or longer than the predetermined value at the detection position, it is preferable not to block light from the light emitting element toward the light receiving element that extends to the length detection position.

The length detection means includes at least two pairs of light emitting elements and light receiving elements attached to the magazine, and a length detection position in a supply path of the fastener in the magazine from a direction different from the length direction of the fastener. And extending first and second light shielding members,
The first light shielding member is pushed in a direction of exiting the supply path by a fastener having a length equal to or greater than the predetermined value present at the length detection position, and is directed from the light emitting element of one pair to the light receiving element. On the other hand, when there is no fastener having a length equal to or longer than the predetermined value at the length detection position while blocking light, the light detection element extends from the one pair of light emitting elements to the light receiving element. Without blocking the light
The second light-shielding member is pushed in the direction of exiting the supply path by a fastener present at the length detection position, and shields light from the other pair of the light-emitting elements toward the light-receiving element, while the length When there is no fastener at the detection position, it is preferable not to block light traveling from the other pair of the light emitting elements to the light receiving element by extending to the length detection position.

  The controller may deactivate the booster circuit when light does not reach the light receiving element from the light emitting element in any pair.

The coil voltage generator includes a power switch circuit including a power switching element provided between the battery and the booster circuit,
The controller may deactivate the booster circuit and switch the power switching element while the voltage of the capacitor rises from an initial voltage to a predetermined voltage equal to or lower than the voltage of the battery.

The booster circuit includes a boosting inductance element, a boosting switching element, and a diode,
The boosting inductance element and the boosting switching element are connected in series between both terminals of the battery,
The capacitor is in series with the boosting inductance element and in parallel with the boosting switching element,
The diode flows a current in a direction of charging the capacitor between a connection point of the boosting inductance element and the boosting switching element and the capacitor, but does not flow a reverse current.
The controller may boost the supply voltage from the battery in the booster circuit by switching the boosting switching element.

In the electric driving machine,
A discharge circuit provided in parallel with the capacitor on the output side of the booster circuit;
The discharge circuit includes a discharge resistor and a discharge switching element connected in series between both terminals of the capacitor, first and second bias resistors connected in series between both terminals of the capacitor, and the first And a bias control switching element provided in parallel with any of the second bias resistor,
A connection point of the first and second bias resistors is connected to a control terminal of the discharge switching element,
The controller controls a voltage of a control terminal of the bias control switching element;
The discharge switching element may be off when the bias control switching element is on, and the discharge switching element may be on when the bias control switching element is off.

  The battery may be detachably attached to the main body, and the bias control switching element may be turned off when the battery is detached from the main body.

Another aspect of the present invention is a method for driving a fastener. This method
A target voltage setting step of setting the boost target voltage to either a first target voltage or a second target voltage higher than the first target voltage;
A capacitor charging step of boosting the voltage of the battery to charge the capacitor to the boost target voltage; and
A step of driving the plunger driving coil from the capacitor charged up to the boost target voltage to project the plunger to the driving preparation position, and pushing out the fastener by the plunger to drive it into the driven material.

  In the target voltage setting step, when the length of the fastener is less than a predetermined value, the boost target voltage is set to the first target voltage, and when the length of the fastener is equal to or greater than the predetermined value, the boost The target voltage may be set to the second target voltage.

In the method of driving the fastener,
Before the capacitor charging step, performing an initial charging step of charging the capacitor from an initial voltage to a predetermined voltage equal to or less than the voltage of the battery,
In the initial charging step, a power switching element provided between the battery and the capacitor may be switched.

  In the fastener driving method, it is preferable that when the battery is detached, a discharging step of turning on a discharging switching element provided in parallel with the capacitor to discharge the capacitor is performed.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  According to the present invention, since the boost target voltage can be selected between the first target voltage and the second target voltage higher than the first target voltage, useless consumption current (power) due to boosting more than necessary. Can be reduced. That is, by boosting the voltage of the battery and charging the capacitor, it is possible to improve efficiency and save energy by reducing the current consumption (electric power) of the circuit, and to suppress the consumption of the battery.

1 is a circuit diagram of an electric driving machine according to an embodiment of the present invention. 2 is a time chart (when nails are short) showing ON / OFF of each switch of the circuit shown in FIG. 1 and time change of the voltage of the capacitor circuit. Time chart showing time change (when nails are long). Similarly, a time chart showing changes over time (when work is stopped after pressure increase). 2 is a flowchart showing the operation of the circuit shown in FIG. FIG. 3 is an external view of the electric driving machine. FIG. 7A is a partial cross-sectional view of FIG. FIGS. 7B and 7C are views taken along the arrow A in FIG. FIGS. 8A to 8C are schematic cross-sectional views enlarging the inside of the magazine for explaining length detection means in the electric driving machine. FIG. 9A is a cross-sectional view taken along line A-A ′ of FIG. FIG. 9B is a cross-sectional view taken along the line B-B ′ of FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, process, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  FIG. 1 is a circuit diagram of an electric driving machine 1 according to an embodiment of the present invention. 2 to 4 are time charts showing ON / OFF of each switch of the circuit shown in FIG. 1 and time change of the voltage of the capacitor circuit 27. FIG. FIG. 5 is a flowchart showing the operation of the circuit shown in FIG. FIG. 6 is an external view of the electric driving machine 1. FIG. 7A is a partial cross-sectional view of FIG.

  The electric driving machine 1 of the present embodiment is an electric nail driving machine that drives a nail as a fastener into a material to be driven such as wood. First, the overall configuration of the electric driving machine 1 will be described mainly with reference to FIGS. 6 and 7A. In addition, the front-back direction and the up-down direction are defined as shown by the arrows in FIG. The nail driving direction is forward.

  The electric driving machine 1 includes a main body 2 and a secondary battery 3 (for example, a lithium ion secondary battery). The secondary battery 3 is detachably attached to the housing 5 of the main body 2 and supplies power to a circuit (described later in FIG. 1) in the main body 2.

  The main body 2 includes, for example, a plunger 501, a spring 510 as a plunger urging means, a plunger driving coil 281, a control box 200, a trigger switch 231, and a push switch inside a resin housing 5. The magazine 4 is attached to the front surface of the housing 5. The control box 200 has most of the circuit of the main body 2 shown in FIG.

  The magazine 4 accommodates a number of nails in a row and sequentially conveys them toward the driving preparation position. The driving preparation position is a space behind the nose portion 7 and in front of the plunger 501 (particularly, a front-end blade portion 501b described later). The nose portion 7 projects forward from the upper end of the magazine 4, and the tip is a nail injection port.

  A trigger switch 231, which is a mechanical switch such as a micro switch, is present (fixed) inside the handle portion 505 of the housing 5. When the operator pulls the trigger 503 in the figure, the rod 504A slidably supported by the housing 5 is pushed backward by the trigger 503, and the arm 504B rotatably supported by the housing 5 is rotated by the rod 504A. The button 231B is pushed by the arm 504B, and the trigger switch 231 is turned on. That is, the trigger switch 231 is a switch that detects the operator's intention. The arm 504B is urged to a state shown in FIG. 7A by a torsion spring (not shown), that is, a state where the button 231B is not pressed, and the trigger switch 231 is turned off when the operator lifts his finger from the trigger 503. Become.

  A push switch 232 that is a mechanical switch such as a micro switch is present (fixed) in the housing 5 at a position close to the nose portion 7. When the operator presses the tip of the nose portion 7 against the workpiece, the push lever 506 is retracted together with the nose portion 7, and the push switch 232 is turned on by the push lever 506 (see FIGS. 7B and 7C). . That is, the push switch 232 is a switch for confirming that the tip of the nose portion 7 forming the nail injection port is pressed against the material to be driven. The push lever 506 is urged forward by a spring (not shown) or the like, and the push switch 232 is turned off when the operator separates the tip of the nose portion 7 from the material to be driven.

  The plunger 501 which is a soft magnetic body integrally includes a proximal end side large diameter portion 501a and a distal end side blade portion 501b. The proximal end large diameter portion 501a has, for example, a cylindrical shape. The distal end blade portion 501b has a smaller diameter than the proximal end large diameter portion 501a and is coaxial with the proximal end large diameter portion 501a. The plunger 501 is coaxial with the plunger drive coil 281.

  In the non-projecting state of the plunger 501 (the state shown in FIG. 7A), the tip blade portion 501b is located inside the plunger drive coil 281 except for a part on the tip side. The proximal-side large-diameter portion 501 a has a part on the distal-side blade part 501 b side inside the plunger drive coil 281, and the remaining part extends rearward of the plunger drive coil 281.

  The plunger drive coil 281 fixed in the housing 5 is a solenoid formed by applying a winding 522 to a bobbin 521. A ring-shaped front damper 525 made of an elastic body such as rubber is held coaxially with the plunger drive coil 281 on the front flange 521a of the bobbin 521. The inner diameter of the front damper 525 is smaller than the outer diameter of the proximal-side large-diameter portion 501a of the plunger 501 and larger than the outer diameter of the distal-end-side blade portion 501b.

  The spring 510 is an extension spring, one end is attached to the rear flange 521b of the bobbin 521, the other end is attached to the proximal end of the proximal-side large-diameter portion 501a, and the plunger 501 is moved backward (from the driving preparation position). Energize in the direction of leaving). The rear damper 526 made of an elastic body such as rubber is fixed to the rear of the plunger 501 in the housing 5 and abuts on the base end surface of the base end side large diameter portion 501a when the plunger is not projected.

  A magnetic force is generated inside the plunger drive coil 281 by the current flowing through the plunger drive coil 281, and the plunger 501 obtains a projecting output toward the driving preparation position by this magnetic force. That is, the plunger 501 protrudes forward (toward the driving preparation position) against the bias of the spring 510 by the magnetic force generated by the plunger drive coil 281. At this time, the protruding amount of the plunger 501 is regulated by the front end surface of the base end side large diameter portion 501 a coming into contact with the front damper 525. When the magnetic force of the plunger drive coil 281 is lost or weakened, the plunger 501 is moved backward (from the driving preparation position) until the base end surface of the base end side large diameter portion 501a abuts on the rear damper 526 by the bias of the spring 510. Return to the direction of leaving.

  Hereinafter, the circuit configuration of the electric driving machine 1 will be described mainly with reference to FIG.

  The main body 2 of the electric driving machine 1 supplies the electric power from the secondary battery 3 to the capacitor circuit 27 and supplies the plunger drive coil 281 with the electric charge, whereby the plunger 501 shown in FIG. Is driven and nails are driven. Further, the nail detection switches 291 and 292 for detecting the length and remaining amount of the nail are provided in the magazine 4 for storing the nail as will be described later. The center of control is a microcomputer (hereinafter referred to as “microcomputer”) 29, and various controls are performed by the output of the microcomputer 29. Details of the circuit configuration will be described below.

  The main body 2 of the electric driving machine 1 includes, as circuit elements, a power switch circuit 21, a battery voltage detection circuit 22, a switch detection circuit 23, a control power supply circuit 24, a booster circuit 25, and a capacitor discharge circuit 26a. A capacitor voltage detection circuit 26b, a capacitor circuit 27 as a capacitor, a plunger drive coil 281, an FET 283 (N-type MOSFET) as a coil energization switch, and a nail detection switch 291 that constitutes a length detection means, 292. Of the circuit elements of the main body 2 shown in FIG. 7, the one excluding the plunger drive coil 281 constitutes a coil voltage generator.

  A power switch circuit 21 for controlling energization with the secondary battery 3 includes an FET 211 (P-type MOSFET) as a power switching element, resistors 212 and 213 as bias resistors, and an FET 214 (bias control switching element). N-type MOSFET). The source terminal of the FET 211 is connected to the plus terminal of the secondary battery 3. The resistors 212 and 213 and the FET 214 are connected in series between the plus terminal and the minus terminal of the secondary battery 3. The resistor 212 is provided between the gate and source of the FET 211. The resistor 213 is provided between the gate terminal (corresponding to a control terminal) of the FET 211 and the drain terminal of the FET 214. The source terminal of the FET 214 is connected to the negative terminal of the secondary battery 3. A gate terminal (corresponding to a control terminal) of the FET 214 is connected to the microcomputer 29.

  The battery voltage detection circuit 22 has resistors 221 and 222 connected in series between the drain terminal of the FET 211 and the negative terminal of the secondary battery 3. A connection point between the resistors 221 and 222 is connected to the microcomputer 29.

  The switch detection circuit 23 includes a trigger switch 231, a push switch 232, and diodes 233 to 235.

  One end of the trigger switch 231 and the push switch 232 is connected to the plus terminal of the secondary battery 3. The other ends of the trigger switch 231 and the push switch 232 are connected to a control power supply circuit 24 to be described later via diodes 235 and 234, and are connected to the minus terminal of the secondary battery 3 and the microcomputer 29 via resistors 236 and 237, respectively. Connected. The diode 233 is provided between the drain terminal of the FET 211 and the control power supply circuit 24.

  A control power supply circuit 24 for supplying power to the microcomputer 29 includes a three-terminal regulator 241 as a power supply circuit and capacitors 242 and 243. The three-terminal regulator 241 steps down the voltage (for example, 14.4 V) of the secondary battery 3 input via the diodes 233 to 235 to the operating voltage (for example, 3.3 V) of the microcomputer 29 and supplies it to the microcomputer 29. . Capacitors 242 and 243 for stable operation are provided between the input terminal and output terminal of the three-terminal regulator 241 and the negative terminal of the secondary battery 3, respectively.

  The booster circuit 25 provided between the FET 211 drain terminal and the negative terminal of the secondary battery 3 includes an inductance 252 as a boosting inductance element, an FET253 (N-type MOSFET) as a boosting switching element, and a current control switching. An FET 254 (N-type MOSFET) as an element, a driver circuit 256, a current detection resistor 255, and a diode 251 are included.

  The inductance 252, the FET 253, and the current detection resistor 255 are connected in series via the power switch circuit 21 between the plus terminal and the minus terminal of the secondary battery 3. One end of the inductance 252 and the cathode terminal of the diode 251 are connected to the drain terminal of the FET 211. The anode terminal of the diode 251 is connected to the negative terminal of the secondary battery 3. The other end of the inductance 252 is connected to the drain terminal of the FET 253 and the source terminal of the FET 254. The source terminal of the FET 253 is connected to the negative terminal of the secondary battery 3 through the resistor 255. A gate terminal (corresponding to a control terminal) of the FET 253 is connected to the microcomputer 29. The gate terminal (corresponding to a control terminal) of the FET 254 is connected to the microcomputer 29 via the driver circuit 256. The driver circuit 256 generates a gate voltage (control voltage) for switching the FET 254. A current detection resistor 255 that detects current is connected to the microcomputer 29, and a terminal voltage is input to the microcomputer 29. The drain terminal of the FET 254 and the source terminal of the FET 253 serve as a plus side output terminal and a minus side output terminal of the booster circuit, respectively, and play a role for charging the capacitor circuit 27 with the power of the secondary battery 3.

  The capacitor circuit 27 includes a plurality of capacitors (for example, electric double layer capacitors) connected in series between the output terminals of the booster circuit 25 (between the drain terminal of the FET 254 and the source terminal of the FET 253). The capacitor circuit 27 receives the output voltage (boosted voltage) of the booster circuit 25 and accumulates (stores) the power supplied from the booster circuit 25.

  The capacitor discharge circuit 26a includes a discharge resistor 264, an FET 265 (N-type MOSFET) as a discharge switching element, resistors 261 and 262 as first and second bias resistors, and an FET 263 (N Type MOSFET).

  The resistors 261 and 262 are connected in series between the output terminals of the booster circuit 25 (between the drain terminal of the FET 254 and the source terminal of the FET 253). A connection point between the resistors 261 and 262 is connected to a gate terminal (corresponding to a control terminal) of the FET 265 and a drain terminal of the FET 263 (N-type MOSFET). The source terminal of the FET 265 and the source terminal of the FET 263 are connected to the negative output terminal of the booster circuit 25 (the source terminal of the FET 253). A gate terminal (corresponding to a control terminal) of the FET 263 is connected to the microcomputer 29. The drain terminal of the FET 265 is connected to the plus side output terminal of the booster circuit 25 (the drain terminal of the FET 254) via the discharge resistor 264.

  The capacitor voltage detection circuit 26b includes resistors 267 and 268 connected in series between the output terminals of the booster circuit 25 (between the drain terminal of the FET 254 and the source terminal of the FET 253). A connection point between the resistors 267 and 268 is connected to the microcomputer 29.

  Note that the combined resistance of the resistors 261 and 262 and the combined resistance of the resistors 267 and 268 are sufficiently larger than the discharge resistor 264. As a result, when the discharge resistor 264 is not energized, the capacitor circuit 27 is less charged and the amount of energy stored in the capacitor array 27 is maintained.

  In parallel with the capacitor circuit 27, a plunger drive coil 281 and an FET 283 are connected in series. A gate terminal (corresponding to a control terminal) of the FET 283 is connected to the microcomputer 29. A diode 282 is connected in parallel with the plunger drive coil 281.

  The nail detection switches 291 and 292 connected to the microcomputer 29 are, for example, switching elements made of phototransistors as light-receiving elements of photointerrupters, and constitute length detection means for detecting the length of the nail as shown below. .

  FIGS. 8A to 8C are schematic cross-sectional views enlarging the inside of the magazine 4 for explaining the length detection means in the electric driving machine 1. 8A shows a long nail at the length detection position in the magazine 4, FIG. 8B shows a short nail at the length detection position, and FIG. 8C shows a length detection position. Indicates when there is no nail (when the remaining amount is insufficient). FIG. 9A is a cross-sectional view taken along the line A-A ′ of FIG. FIG. 9B is a cross-sectional view taken along the line B-B ′ of FIG.

  The magazine 4 holds a large number of nails 101 in a row in the nail conveyance path 402 in the guide 401, and is moved upward by a pusher 403 biased upward by a biasing means such as a spring (not shown). This is a configuration that pushes out. The photo interrupters 29A and 29B, the non-transparent rod-like members 295 and 296 as light shielding members, and the spring 298 (see FIG. 9) constitute nail length detecting means.

  As shown in FIGS. 9A and 9B, the photo interrupter 29B is fixed to the inner wall surface of the magazine 4 and has a light emitting portion 29S and a light receiving portion 29R. The light receiving unit 29R includes a nail detection switch 292 (see FIG. 1) made of, for example, a phototransistor that is turned on / off according to whether light is received from the light emitting unit 29S. The photo interrupter 29A has the same configuration as the photo interrupter 29B, and includes a nail detection switch 291 (see FIG. 1).

  The rod-shaped member 296 is slidably supported by the opening 401 a on the side surface of the guide 401, and the tip can protrude into the nail conveyance path 402. The position where the bar-like member 296 protrudes when viewed from the length direction of the nail 101 in the nail conveyance path 402 is the length detection position. The spring 298 is an extension spring, one end is attached to the end of the rod-like member 296, and the other end is attached to the side surface of the guide 401, and urges the rod-like member 296 toward the nail conveyance path 402. The bar-shaped member 295 has the same shape as that of the bar-shaped member 296, is slidably supported by the opening 401 b on the side surface of the guide 401, and is urged by a spring (not shown) similarly to the bar-shaped member 296.

The length detection means has the following three states.
1. When a long nail is present at the length detection position of the nail conveyance path 402, the rod-like members 295 and 296 are both pushed out of the nail conveyance path 402 by the long nail, and the light interrupters 29A and 29B emit light from the light emitting part to the light receiving part. Block the light. For this reason, both the nail detection switches 291 and 292 are turned off.
2. When a short nail exists at the position where the length of the nail conveyance path 402 is detected, the rod-like member 296 extends to the nail conveyance path 402 by the bias of the spring 298 and the light beam from the light emitting portion 29S of the photo interrupter 29B to the light receiving portion 29R. On the other hand, the rod-shaped member 295 is pushed out of the nail conveyance path 402 by a short nail against the bias of the spring, and blocks the light beam from the light emitting portion to the light receiving portion of the photo interrupter 29A. For this reason, the nail detection switch 292 is turned on and the nail detection switch 291 is turned off.
3. When the nail does not exist at the position where the length of the nail conveyance path 402 is detected, the rod-like members 295 and 296 are both extended to the nail conveyance path 402 by the bias of the spring, and the photo interrupters 29A and 29B are sent from the light emitting part to the light receiving part. Do not block light. For this reason, both the nail detection switches 291 and 292 are turned on.

  Finally, the LD terminal of the secondary battery 3 is connected to the microcomputer 29. The LD terminal is a terminal for transmitting an overdischarge detection signal to the microcomputer 29 when the voltage of each cell constituting the secondary battery 3 becomes a predetermined value or less. That is, the secondary battery 3 is formed by connecting, for example, 4 cells of 3.6 V lithium ion secondary batteries in series, and has a monitoring IC for monitoring the voltage of each cell. This monitoring IC transmits an overdischarge detection signal from the LD terminal when the voltage is at or below a predetermined value in at least one of the cells. When the microcomputer 29 receives the overdischarge detection signal, it turns off the FET 214, notifies the operator of the overdischarge by display or sound, and turns itself off after a predetermined time.

  Hereinafter, the operation of the electric driving machine 1 will be described mainly with reference to FIGS. 2 is a time chart when the nail in the magazine 4 is short, FIG. 3 is a time chart when the nail in the magazine 4 is long, and FIG. 4 is a time chart when the nail in the magazine 4 is long and the operation is stopped after pressurization.

  In the initial state, the voltage of the capacitor circuit 27 is 0, and each switch (including the switching element) is off.

  The operation of the electric driving machine 1 starts when either the trigger switch 231 or the push switch 232 is turned on by the operator's operation (t0 in FIGS. 2 to 4). Whether the trigger switch 231 or the push switch 232 is turned on is appropriately determined by the operator according to the work content.

  When either the trigger switch 231 or the push switch 232 is turned on, the positive switch of the secondary battery 3 passes through the switch that is turned on and the diode (either one of the diodes 234 and 235) connected thereto. A voltage is applied to the control power circuit 24. The microcomputer 29 is activated by the output of the control power circuit 24.

(Initial charging step: t0 to t1 in FIGS. 2 to 4)
The microcomputer 29 turns on the FET 263 (S1 in FIG. 5), lowers the potential of the gate terminal of the FET 265, and turns off the FET 265. Thereby, the energization of the discharge resistor 264 is stopped.

  The microcomputer 29 switches the FET 214 (S2 in FIG. 5). As a result, the FET 211 also performs switching in synchronization and a voltage is applied to the control power supply circuit 24 via the diode 233. For this reason, even if the trigger switch 231 and the push switch 232 are turned off, the activation state of the microcomputer 29 can be maintained.

  At this time, the booster circuit 25 is inactive (no boosting operation is performed), and the FET 253 is off. For this reason, the capacitor circuit 27 is charged from the secondary battery 3 through the inductance 252 of the booster circuit 25 and the parasitic diode of the FET 254. Here, since the FET 211 is switched (intermittently on), the current is limited by the inductance 252 and no inrush current to the capacitor circuit 27 is generated. The flyback current of the inductance 252 is returned by the diode 251. Thereby, the inrush current from the secondary battery 3 to the capacitor circuit 27 can be suppressed, and the cost can be made appropriate without making the rated values of the FET 211 and FET 254 excessive.

  The switching operation of the FET 211 by the microcomputer 29 ends when the voltage of the secondary battery 3 and the voltage of the capacitor circuit 27 are substantially equal (S3 in FIG. 5). Thereafter, the microcomputer 29 turns on the FET 214, that is, the FET 211 to supply the power of the secondary battery 3 to the booster circuit 25 (S4 in FIG. 5). Then, the voltage of the capacitor circuit 27 immediately coincides with the voltage of the secondary battery 3 (t1 in FIGS. 2 to 4). Thereafter, the process proceeds to determination of whether or not boosting is necessary. That is, the microcomputer 29 detects the on / off state of the trigger switch 231 and the push switch 232 (S5 and S6 in FIG. 5). This is performed by the microcomputer 29 detecting the voltage across the resistor 236 or 237 generated by the on operation of the switch.

(Target voltage setting process)
Then, when either or both of the trigger switch 231 and the push switch 232 are on, the state of the nail detection switches 291 and 292 is detected (S7 and S8 in FIG. 5). First, the state of the nail detection switch 291 is detected (S7 in FIG. 5), and when it is on, it is determined that there is no nail (insufficient remaining amount), and the boost target voltage is the voltage of the secondary battery 3 (S9 in FIG. 5). ). That is, the voltage is not boosted by the booster circuit 25 and the voltage of the secondary battery 3 is applied to the capacitor circuit 27 as it is. When the nail detection switch 291 is off, the output of the nail detection switch 292 is detected (S8 in FIG. 5). When the nail detection switch 292 is off, it is determined that the nail is a long nail, and the boost target voltage is set to V2 (S10 in FIG. 5). When the nail detection switch 292 is on, it is determined that the nail is a short nail, and the boost target voltage is set to V1 (S11 in FIG. 5). Here, V1 <V2. This is because long nails require more energy. Moreover, since an appropriate energy can be set according to the length of the nail, the energy of the secondary battery 3 can be used effectively, energy saving can be achieved, and the work amount per charge can be improved. As an example of the boost target voltage, V1 is 100V and V2 is 150V. However, the boost target voltage may be determined in consideration of the weight of the nail, the material of the driven material, and other factors.

(Capacitor charging step: t1 to t2 in FIG. 2, t1 to t2 ′ in FIGS. 3 and 4)
After setting the boost target voltage to V1 or V2, the microcomputer 29 switches the FET 253 (S12 in FIG. 5) and causes the booster circuit 25 to perform a boost operation. That is, when the FET 253 is turned on, a current flows through the inductance 252 and the FET 253. When the FET 253 is turned off, the flyback current of the inductance 252 is charged to the capacitor circuit 27 via the parasitic diode of the FET 254, and the voltage of the capacitor circuit 27 is boosted toward a target voltage higher than the voltage of the secondary battery 3. It will be done.

  The voltage of the capacitor circuit 27 is detected by inputting the voltage divided by the resistors 267 and 268 to the microcomputer 29. When the voltage of the capacitor circuit 27 reaches the boost target voltage (V1 or V2) set as described above, the switching of the FET 253 is stopped (S13 and S14 in FIG. 5). Note that during the period when the capacitor circuit 27 is charged from the secondary battery 3, the terminal voltage of the secondary battery 3 slightly decreases due to the voltage drop caused by the internal resistance (however, this decrease is not shown in the time chart). ).

(Punching process: t3 to t4 in FIG. 2, t3 ′ to t4 ′ in FIG. 3)
Next, it is detected whether both the trigger switch 231 and the push switch 232 are on (S15 and S16 in FIG. 5), and the microcomputer 29 turns on the FET 283 only when both are on (S17 in FIG. 5). Then, the electric charge accumulated in the capacitor circuit 27 is energized to the plunger drive coil 281. As a result, the plunger 501 forming the magnetic circuit of the plunger drive coil 281 is driven (the blade portion 501b protrudes toward the driving preparation position) and the nail is driven. Then, after a predetermined time (for example, 10 to 50 milliseconds) elapses, the FET 283 is turned off (S18 and S19 in FIG. 5), and the current flowing through the plunger drive coil 281 flows back through the diode 282 and is consumed. The nail driving for one shot is thus completed.

  Thereafter, it is confirmed that at least one of the trigger switch 231 and the push switch 232 is turned off (S20, S21 in FIG. 5), and the process returns to the determination of necessity of boosting (S5 in FIG. 5). At this time, the voltage of the capacitor circuit 27 is substantially equal to the voltage of the secondary battery 3. Thereafter, the second and subsequent shots are executed as necessary in the same flow as the first shot (after t5 in FIG. 2, after t5 ′ in FIG. 3).

(Return charging process: t23 to t24 in FIG. 4)
Hereinafter, the return charging process for charging the secondary battery 3 from the capacitor circuit 27 will be described. A typical example of performing this process is to stop the operation without performing driving (after the operation S14 in FIG. 5) after the voltage of the capacitor circuit 27 reaches the boost target voltage (V1 or V2) (after the operation of the operator). This is a case where both the trigger switch 231 and the push switch 232 are turned off by the operation (N in S15 and S22 in FIG. 5). In this case, the microcomputer 29 switches the FET 254 via the driver circuit 256 (S23 in FIG. 5). As a result, the voltage charged in the capacitor circuit 27 charges the secondary battery 3 through the FET 254, the inductance 252 and the parasitic diode of the FET 211. When FET 254 is turned off, the flyback current of inductance 252 flows back through the parasitic diode of FET 253. Further, since the current flows through the resistor 255 when the FET 254 is switched, the microcomputer 29 can detect the voltage of the resistor 255 and appropriately control the charging from the capacitor circuit 27 to the secondary battery 3.

  The return charging step is executed until the difference between the voltage of the secondary battery 3 and the voltage of the capacitor circuit 27 becomes equal to or lower than the predetermined voltage value V3 (S24 in FIG. 5), and then the FET 254 is turned off (S25 in FIG. 5). Then, a discharge standby state is entered. Note that, by charging the secondary battery 3 from the capacitor circuit 27, the terminal voltage of the secondary battery 3 slightly increases (recovers) from before the charge is performed (however, this increase is not shown in the time chart). ).

(Discharge process: t25 in FIG. 4)
Hereinafter, a discharging process from a state in which the voltage of the secondary battery 3 and the voltage of the capacitor circuit 27 are substantially the same will be described. For example, when the work is finished, both the trigger switch 231 and the push switch 232 are turned off by the operator's operation (N in S5 and S6 in FIG. 5). Then, a discharge standby state is entered, and the microcomputer 29 turns off the FETs 214 and 263 after waiting for a predetermined time (for example, 30 seconds) (S26 and S27 in FIG. 5). When the FET 214 is turned off, the FET 211 is also turned off, the secondary battery 3 is cut off, and the current consumption of the secondary battery 3 is reduced. Further, when the FET 263 is turned off, a voltage obtained by dividing the voltage of the capacitor circuit 27 by the resistors 261 and 262 is applied to the gate terminal of the FET 265, so that the FET 265 is turned on. Thereby, the electric charge of the capacitor circuit 27 is discharged through the discharge resistor 264 and the FET 265. When it is determined that there is no nail (insufficient remaining amount), a discharge standby state is entered (S9 → S26 in FIG. 5), and the discharge process is similarly performed.

  The above discharge step (S27 in FIG. 5) is automatically performed even when, for example, the secondary battery 3 is unexpectedly pulled out from the main body 2 of the electric driving machine 1. That is, when the secondary battery 3 is removed, the microcomputer 29 is turned off, and the FETs 214 and 263 are also turned off. For this reason, even if the secondary battery 3 is unexpectedly removed, the charge accumulated in the capacitor circuit 27 can be discharged quickly, so that the reliability is high.

  According to the present embodiment, the following effects can be achieved.

(1) At least two types of boost target voltage (capacitor 27 charging target voltage) can be set. For long nails, the boost target voltage is set to V2, and for short nails, the boost target voltage is set to V1. Therefore, unlike the case where there is only one type of boost target voltage, there is no excessive charging due to the short nail. That is, when the short nail is driven, if the capacitor circuit 27 is charged to the same voltage as that of the long nail, an unnecessary driving force is provided (overpower supply), which is a waste of battery energy. In the embodiment, it is possible to suitably reduce such waste. For this reason, it is possible to improve efficiency and save energy by reducing current consumption (electric power) of the circuit, and to suppress battery consumption.

(2) By performing the above-described return charging step, the charging energy of the capacitor circuit 27 (a portion higher than the voltage of the secondary battery 3) is transferred to the secondary battery 3 even when the boosted voltage is not applied. Can be recovered (reducing waste of charging energy). For this reason, it is possible to improve efficiency and save energy by reducing the current consumption (electric power) of the circuit as compared with the case where the return charging step is not performed, and to suppress the consumption of the battery.

(3) In the above-described initial charging step, the FET 211 is switched while the capacitor circuit 27 is charged from the initial voltage (for example, zero) until it becomes substantially equal to the voltage of the secondary battery 3, so that the current is limited by the inductance 252. Thus, an inrush current to the capacitor circuit 27 can be prevented. In the above-described return charging step, since the FET 254 is switched, the current is limited by the inductance 252 and an excessive current can be prevented from flowing from the capacitor circuit 27 to the secondary battery 3. Therefore, the rated values of the FET 211 and the FET 254 are small compared with the case where the switching is not performed, and the size and cost can be reduced. Moreover, the lifetime reduction of the secondary battery 3 and the capacitor circuit 27 by an excessive electric current (rush current) can be suppressed.

(4) When the operator pulls the trigger 503 (that is, when the trigger switch 231 is turned on), the capacitor circuit 27 is automatically charged toward the boost target voltage (V1 or V2). When the tip of the portion 7 is pressed against the material to be driven, the charging of the capacitor circuit 27 is completed or has progressed halfway, so the time from the operator's operation until the nail is driven can be shortened (response Operability can be improved. The same effect can be obtained when the trigger 503 is pulled after the tip of the nose portion 7 is pressed against the workpiece.

(5) Since the capacitor circuit 27 is automatically discharged when the secondary battery 3 is removed, the reliability is good.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  There may be three or more boost target voltages.

  The secondary battery 3 may be a secondary battery other than the lithium ion secondary battery. Further, a primary battery may be used in place of the secondary battery 3.

  Each switching element may be a non-contact switch (electronic switch) other than the FET.

  Instead of or in addition to using a parasitic diode between the drains and sources of the FETs 211, 253, and 254 as a current path, a separate diode may be connected in parallel between the drains and sources to form a current path.

  The discharge waiting time (S26 in FIG. 5) differs between when both the trigger switch 231 and the push switch 232 are off (N in S6 in FIG. 5) and when there is no remaining fastener (S9 in FIG. 5). May be.

  A waiting time may be set between the time when the trigger switch 231 and the push switch 232 are both turned off after boosting and before the switching of the FET 254 is started (between S22 and S23 in FIG. 5). This is because work may be resumed immediately even when both the trigger switch 231 and the push switch 232 are turned off.

  In the length detection means, instead of optical length detection by a photo interrupter, mechanical length detection that turns on and off two mechanical switches depending on whether or not the length of the fastener is equal to or greater than a predetermined value may be used. Good.

DESCRIPTION OF SYMBOLS 1 Electric driving machine 2 Main part 3 Secondary battery 21 Power switch circuit 22 Battery voltage detection circuit 23 Switch detection circuit 24 Control power supply circuit 25 Boost circuit 26a Capacitor discharge circuit 26b Capacitor voltage detection circuit 27 Capacitor circuit 29 Microcomputer 211, 214 253, 254, 263, 265, 283 FET
231 Trigger switch 232 Push switch 252 Inductance 281 Plunger drive coil 291, 292 Nail detection switch

Claims (13)

A main body and a battery for supplying power to the main body,
The main body includes a magazine for supplying a fastener to a driving preparation position, a plunger capable of driving the fastener existing in the driving preparation position by projecting toward the driving preparation position, and the plunger. Plunger urging means for urging in a direction away from the driving preparation position, a plunger driving coil for generating a magnetic force that gives the plunger a projecting output to the driving preparation position, and a supply voltage to the plunger driving coil A coil voltage generator for generating
The coil voltage generator includes a booster circuit that boosts a supply voltage from the battery, a capacitor to which an output voltage of the booster circuit is applied and provided in parallel with the plunger drive coil, and the plunger from the capacitor A coil energization switch capable of switching on / off of energization to the drive coil, and a controller for controlling at least the booster circuit;
The controller is capable of switching a boost target voltage of the booster circuit between a first target voltage and a second target voltage higher than the first target voltage. . In the electric driving machine according to claim 1,
A length detecting means for detecting whether or not the length of the fastener existing in the magazine is a predetermined value or more;
When the length detecting means detects that the length of the fastener is less than the predetermined value, the controller sets the boost target voltage of the booster circuit as the first target voltage, and sets the length of the fastener. When the length detection means detects that the value is equal to or greater than the predetermined value, the booster target voltage of the booster circuit is set as the second target voltage. In the electric driving machine according to claim 2,
The length detection means includes at least a pair of light emitting elements and light receiving elements attached to the magazine, and a light shielding member extending to a length detection position in a supply path of a fastener in the magazine,
The light blocking member is pushed in a direction of exiting the supply path by a fastener having a length equal to or greater than the predetermined value present at the length detection position, and blocks light from the light emitting element toward the light receiving element. An electric driving machine that extends to the length detection position and does not block light traveling from the light emitting element to the light receiving element when there is no fastener having a length equal to or greater than the predetermined value at the height detection position. In the electric driving machine according to claim 2,
The length detection means includes at least two pairs of light emitting elements and light receiving elements attached to the magazine, and a length detection position in a supply path of the fastener in the magazine from a direction different from the length direction of the fastener. And extending first and second light shielding members,
The first light shielding member is pushed in a direction of exiting the supply path by a fastener having a length equal to or greater than the predetermined value present at the length detection position, and is directed from the light emitting element of one pair to the light receiving element. On the other hand, when there is no fastener having a length equal to or longer than the predetermined value at the length detection position while blocking light, the light detection element extends from the one pair of light emitting elements to the light receiving element. Without blocking the light
The second light-shielding member is pushed in the direction of exiting the supply path by a fastener present at the length detection position, and shields light from the other pair of the light-emitting elements toward the light-receiving element, while the length An electric driving machine that extends to the length detection position and does not block light from the other pair of the light emitting elements toward the light receiving element when no fastener exists at the detection position.   5. The electric driving machine according to claim 4, wherein the controller deactivates the booster circuit when light does not reach the light receiving element from the light emitting element in any pair. In the electric driving machine according to any one of claims 1 to 5,
The coil voltage generator includes a power switch circuit including a power switching element provided between the battery and the booster circuit,
The controller is configured to make the booster circuit inactive and switch the power switching element while the voltage of the capacitor rises from an initial voltage to a predetermined voltage equal to or lower than the voltage of the battery. Embedded machine. In the electric driving machine according to any one of claims 1 to 6,
The booster circuit includes a boosting inductance element, a boosting switching element, and a diode,
The boosting inductance element and the boosting switching element are connected in series between both terminals of the battery,
The capacitor is in series with the boosting inductance element and in parallel with the boosting switching element,
The diode flows a current in a direction of charging the capacitor between a connection point of the boosting inductance element and the boosting switching element and the capacitor, but does not flow a reverse current.
The controller is an electric driving machine that boosts a supply voltage from the battery in the boosting circuit by switching of the boosting switching element. In the electric driving machine according to any one of claims 1 to 7,
A discharge circuit provided in parallel with the capacitor on the output side of the booster circuit;
The discharge circuit includes a discharge resistor and a discharge switching element connected in series between both terminals of the capacitor, first and second bias resistors connected in series between both terminals of the capacitor, and the first And a bias control switching element provided in parallel with any of the second bias resistor,
A connection point of the first and second bias resistors is connected to a control terminal of the discharge switching element,
The controller controls a voltage of a control terminal of the bias control switching element;
The electric driving machine in which the discharge switching element is off when the bias control switching element is on, and the discharge switching element is on when the bias control switching element is off.   9. The electric driving machine according to claim 8, wherein the battery is detachably attached to the main body, and the bias control switching element is turned off when the battery is detached from the main body. Driving machine. A target voltage setting step of setting the boost target voltage to either a first target voltage or a second target voltage higher than the first target voltage;
A capacitor charging step of boosting the voltage of the battery to charge the capacitor to the boost target voltage; and
A fastener that has a driving step of projecting a plunger to a driving-in preparation position by energizing a plunger driving coil from a capacitor charged to the boost target voltage, and pushing out the fastener with the plunger and driving it into a workpiece. How to drive   11. The method according to claim 10, wherein, in the target voltage setting step, when the length of the fastener is less than a predetermined value, the boost target voltage is set to the first target voltage, and the length of the fastener is the height. A fastener driving-in method in which the boost target voltage is set to the second target voltage when it is equal to or greater than a predetermined value. 12. The method according to claim 10 or 11,
Before the capacitor charging step, performing an initial charging step of charging the capacitor from an initial voltage to a predetermined voltage equal to or less than the voltage of the battery,
In the initial charging step, a fastener driving method for switching a power switching element provided between the battery and the capacitor.   13. The method according to claim 10, wherein when the battery is detached, a discharging step is performed in which the discharging switching element provided in parallel with the capacitor is turned on to discharge the capacitor. How to drive the fasteners.

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