JP2012066333A - Electric tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a wide working area to be covered by one tool body and a battery pack because a plurality of voltages can be easily selected one battery pack.SOLUTION: An electric tool includes a battery pack 2 incorporating a battery pack part in which a plurality of secondary batteries are connected and a tool body 1 including a driving unit 3 operated with the battery pack as a power supply. The battery pack 2 includes a plurality of terminals capable of output of different voltages. The tool body includes a voltage switching unit 9 selecting a voltage to be supplied to the driving unit via the terminals of the battery pack.

Description

  The present invention relates to an electric power tool, and more particularly to an electric power tool including a detachable battery pack containing a secondary battery.

  Battery packs for power tools are prepared with different numbers of battery cells connected in series according to the output voltage. When performing light work and heavy work together, the output voltage will be adjusted according to each work. In many cases, work is performed by combining a plurality of different battery packs and a tool body corresponding to each battery pack, or all work is performed with a battery pack suitable for heavy work and a corresponding tool body.

  However, it is expensive to prepare a plurality of battery packs and a plurality of types of tool bodies. Also, when a light work is performed for heavy work, very delicate operation is required, and the work becomes difficult.

  For this purpose, Japanese Patent Laid-Open No. 10-29172 discloses that one (or two or more) of the plurality of battery cells contained in the battery pack has the same shape as the battery cell, and the + terminal and the − terminal are short-circuited. A battery that changes the voltage output from the battery pack by changing to a dummy battery has been proposed.

  However, in order to change the voltage during the work, it is necessary to replace the battery cell and the dummy battery, and the voltage cannot be easily changed.

  Although it is possible to change the output voltage of the battery pack by providing a voltage switching unit for switching the connection between the battery cells in the battery pack so that the output voltage of the battery pack can be changed. Since it is common to purchase a battery pack, providing the voltage switching unit on the battery pack side increases the overall cost and the size of the battery pack.

  In addition, the voltage range for the tool body is determined according to the specifications of the built-in motor. However, if a voltage switching unit is provided on the battery pack side, a battery pack with an unsuitable voltage may be connected to the tool body. become.

JP-A-10-29172

  The present invention has been made in view of these points, and provides a power tool capable of easily selecting a plurality of voltages with a single battery pack and covering a wide work area with a single tool body and battery pack. It is an object to do.

  The present invention relates to an electric tool comprising a battery pack containing an assembled battery to which a plurality of secondary batteries are connected, and a tool body having a drive unit that operates using the battery pack as a power source. The tool main body includes a voltage switching unit that selects a voltage to be supplied to the driving unit through the terminal of the battery pack.

  The tool body includes a plurality of power connection terminals that are respectively connected to a plurality of terminals in the battery pack, and the voltage switching unit turns on and off the connection between the plurality of power connection terminals and the drive unit. What is a switch can be suitably used, and the tool body includes a power connection terminal that is selectively connected to a plurality of terminals in the battery pack, and the voltage switching unit is connected to the power connection terminal. It may be a position changing mechanism for the selection. In the latter case, the number of terminals can be reduced and a switch is not necessary, so that the cost can be reduced.

  The tool body includes a voltage operation unit, and the voltage switching unit switches the voltage according to the operation of the voltage operation unit, and the tool body includes a detection unit that detects the state of the drive unit, You may provide the control part which makes a voltage switch part switch a voltage according to the state detected by the detection part.

  In the present invention, since the voltage can be switched freely according to the usage, it can be used for various work, and since there is a voltage switching part on the tool body side, it depends on the type of the electric tool. Since the voltage range that can be switched can be limited, and it is not necessary for the user to be aware of the corresponding voltage, it is easy to use, and it can not be switched to a voltage that is not compatible, It is also possible to prevent damage to the tool body.

It is a block circuit diagram of an example of an embodiment of the invention. It is a perspective view same as the above. It is a perspective view of a battery pack same as the above. It is a perspective view of a tool main part same as the above. It is a torque-rotation speed characteristic figure of a motor same as the above. It is a perspective view of another example. It is a circuit diagram same as the above. (a) and (b) are the fragmentary perspective views of the tool main body in another example. It is a circuit diagram same as the above. It is a circuit diagram of another example. It is a circuit diagram of another example. It is a circuit diagram of another example. It is a circuit diagram of the battery pack in another example.

  The power tool shown in FIG. 2 is of a type called a drill driver. The power tool shown in FIG. 2 has a chuck handle 15 at the tip and includes a driving motor, a speed reducer, and the like. It consists of a tool main body 1 disposed inside and a battery pack 2 that is detachable at the tip of a grip portion 11 extending from the middle of the tool main body 1. In the figure, 12 is a trigger switch handle, 13 is a forward / reverse rotation switching switch, and 14 is a hanging clip.

  As shown in FIG. 1, the battery pack 2 includes a plurality of battery cells C1, C2, and C3 that are secondary batteries, and these battery cells C1, C2, and C3 are connected in series. As shown in FIG. 3, in addition to the terminal B− connected to the cathode of the battery cell C1 and the terminal B3 connected to the anode of the battery cell C3, it is connected between the battery cells C1 and C2. A terminal B1 and a terminal B2 connected between the battery cells C2 and C3 are provided, and three different voltages can be output.

  As shown in FIG. 4, four power connection terminals I0, I1, I2, and I3 are provided at the lower end of the grip part 11 that is the battery pack connection part on the tool body 1 side. When mounted, these power connection terminals I0, I1, I2, and I3 are connected to the four terminals B-, B1, B2, and B3 of the battery pack 2, respectively.

  In addition, the positions of the terminals B-, B1, B2, and B3 in the battery pack 2 are provided at positions defined according to the output voltage, and the power connection terminals I0, I1, I2, and I3 of the tool body 1 are similarly provided. It is provided at the specified position.

  In the tool body 1, the driving unit 3 that is the motor described above, a detection unit 4 that detects the state of the driving unit 3, a switching unit 5 for controlling energization to the driving unit 3, the trigger switch 12, and forward / reverse In addition to the operation unit 6 including the rotation switch 13 and the like, the control unit 7 that controls the operation of the switching unit 5, and the control power supply unit 8, a voltage switching unit 9 is provided.

  The voltage switching unit 9 in which the power supply connection terminals I1, I2, and I3 are connected to the input side switches the power supply connection terminals I1, I2, and I3 connected to the drive unit 3 to thereby change the voltage applied to the drive unit 3. FIGS. 6 and 7 show an example when the voltage switching unit 9 is configured by a rotary switch having mechanical contacts. 7, 41 is a thermistor for detecting the temperature of the drive unit (motor) 3, 42 is a current detection unit for detecting the motor current, and the thermistor 41 and the current detection unit 42 constituting the detection unit 4 are control units. The detection result is input to 7.

  The trigger switch 12 in the operation unit 6 is for performing on / off of the power tool and adjusting the rotation speed, and has a built-in variable volume that varies in proportion to the pull amount of the trigger switch. Is output to the control unit 7. The control unit 7 is composed of a microcomputer, reads the amount of operation of the trigger switch 12 of the operation unit 6 by AD conversion, drives the switching unit 5 according to the table set inside, and drives the motor by changing the duty ratio. Control the rotation of An Nch FET is used for the switching unit 5, and a PWM signal is sent from the control unit 7 to the gate of the switching unit 5 (FET) to control the driving unit 3 which is a DC motor.

  As shown in FIG. 5, the direct current motor as the drive unit 3 has a linear relationship between the torque and the rotational speed if the applied voltage is constant, and increases the maximum rotational speed and the starting torque when the applied voltage is increased. Therefore, it is possible to work with a higher load.

  Therefore, in this electric power tool, for example, by switching to the terminal I1 connected to the terminal B1, a voltage suitable for light work can be applied to the drive unit 3, and by switching to the terminal I3 connected to the terminal B3, A voltage suitable for heavy work can be applied to the drive unit 3.

  If it is an electric tool with such a function, when working with torque that is higher than usual, it is possible to respond without the need to purchase and prepare a high-voltage electric tool that can produce high torque. If the work output is damaged when the above output is generated, the voltage can be set low to prevent damage even if it is wrong.

  In the electric tool, the range of voltage that can be used differs depending on the assumed work and the performance of the drive unit (motor), but the voltage switching unit 9 is not on the battery pack 2 side but on the tool body 1 side. Therefore, the voltage range that can be switched according to the type of the electric tool can be set in the tool main body 1, and the tool main body 1 corresponds to the user. Since the battery pack 2 having a voltage within a compatible range can be used without being aware of the voltage, and a voltage that is not compatible is not input, the tool body 1 may be damaged. It can also be prevented.

  When a high voltage is input to the drive unit 3, the maximum number of revolutions and the starting torque can be increased. However, since the motor current also increases, the temperature rises with long-term use, and there is a possibility that heat and smoke are generated. The detection unit 4 is provided with a detection unit for detecting the state of the motor for protecting the motor, and is for protecting the motor by feeding back the abnormality to the control unit 7. The current detection unit 42 shown in FIG. A current detection resistor is attached after the motor output, and the voltage at both ends thereof is amplified by an operational amplifier and input to the control unit 7, and the thermistor 41 detects the motor temperature.

  Now, when the user switches to the terminal B3 (power supply voltage terminal I3) by the voltage switching 9, the working range in which the voltage can be increased is widened, but the motor current is increased and the motor temperature is increased. When the current detection unit 42 detects a current exceeding the maximum current in the switching unit 5 or when the thermistor 41 detects a temperature exceeding the heat resistance temperature of the motor winding, the control unit 7 shortens the PWM ON time. Reduce the current value to suppress further heat generation. Further, if the temperature further rises, it has a function of stopping the motor.

  As information to be detected for protection, in addition to the motor drive current and the motor temperature, the temperature of the gear block, the number of rotations of the motor, the number of rotations after being increased or decreased by a gear, and the like can be used.

  The control power supply unit 8 supplies a control voltage of a constant voltage to the control unit 7 and the detection unit 4 regardless of voltage switching by operation of the voltage switching unit 9 or the remaining battery level. Incidentally, when the battery cell in the battery pack 2 is a lithium battery, the voltage range that can be supplied from the battery pack 2 having the three battery cells in the illustrated example is 4.2 V for the maximum voltage and 2 V for the minimum voltage. Then, it becomes 2V-12.6V. Therefore, when the control unit 7 is driven at 5 V, a step-up / step-down circuit is used for the control power source unit 8.

  In the above example, the voltage switching unit fixes B-, which is GND, and switches the voltage by switching B1-B3. However, it is the same by fixing B3 and switching B--B2 on the GND side of the circuit. The effect of can be obtained.

  As the voltage switching unit 9, in addition to a switch having a mechanical contact, as shown in FIGS. 8 and 9, at least one of two power connection terminals I 0 and I 1 provided on the tool body 1 can be operated by sliding operation. The position may be changed. In the illustrated example, the voltage applied to the drive unit 3 can be switched by changing the power connection terminal I1 to a position connected to any one of the terminal B1, the terminal B2, or the terminal B3 of the battery pack 2. Yes. In this case, since the contact for voltage switching becomes unnecessary, cost can be held down.

  A switch in which a voltage switching switch is replaced with a semiconductor element or a relay may be used. FIG. 10 shows a semiconductor device (PchFET) T1, T2, T3 replaced. The control unit 7 selects a voltage by turning on one of the semiconductor elements T1, T2, and T3 according to an input signal from the voltage operation unit 16. When the semiconductor elements T1, T2, and T3 are used, the lifetime can be greatly extended because the contacts are not worn. In addition, when a mechanical switch contact is used, the voltage operation unit 16 must be installed in the vicinity of the contact or in a range that can be operated by a link mechanism in order to switch by the physical movement of the voltage operation unit. Although the installation place of the voltage operation unit 16 is limited, in the case of a semiconductor element, the voltage operation unit 16 only needs to be electrically connected. Since there are no restrictions and no physical operation amount is required, the voltage operation unit 16 can be constituted by an electronic switch such as a tactile switch for small signals. The switch can be switched without having to re-grip the grip or operate it with the other hand. Next, a very good usability.

  If the power tool can be operated with either hand, it can be operated, for example, in the front of the grip part 11 (near the trigger switch 12) and placed in a part that is not hidden by the fingers that grip the grip part 11, Become.

  Further, as the semiconductor elements T1, T2, T3, a PNP transistor or the like can be used in addition to the PchFET. However, there is no problem with a tool with a small driving current, but when the driving current exceeds 20 A even in a steady state like a drill driver, a transistor requires a large heat sink due to large heat generation.

  As shown in FIG. 11, when the voltage is switched by switching the ground line of the driving unit 3, NchFETs or NPN transistors may be used as the semiconductor elements T1 to T3. In particular, the cost of NchFETs is lower than that of PchFETs and there are abundant ones with low on-resistance, so the heat sink can be made smaller and the cost can be reduced.

  In each of the above examples, the voltage is switched by the user's voltage switching operation. For example, the change of the motor rotation speed during the operation is monitored, and the control unit 7 automatically switches the voltage according to the result. You may make it perform. An example of this case is shown in FIG. Here, the voltage switching unit 9 is composed of semiconductor elements T1 to T3 that are on / off controlled by the control unit 7, and an encoder 43 for detecting the rotational speed is provided as the detection unit 4 in addition to the thermistor 41 and the current detection unit 42. The controller 7 switches the voltage based on the change in the motor rotation speed detected by the encoder 43.

  For example, when a normal operation is performed by supplying current to the drive unit 3 through the terminal B2 and the power supply connection terminal I2 by turning on the semiconductor element T2, the load increases (for example, a blade is attached to a tree node). When the motor speed decreases, the control unit 7 that detects the decrease in the speed through the encoder 43 increases the supplied voltage by turning on the semiconductor element T3 and turning off the semiconductor elements T2 and T1. By increasing the torque of the motor, the work can be continued. As described above, the control unit 7 automatically switches the voltage from the value detected by the detection unit 4, so that it is possible to improve the workability by omitting the user's operation.

  Of course, the current detection unit 42 monitors the current so that the switching unit 5 is not broken, and the thermistor 41 monitors the temperature to prevent damage due to heat generation of the motor, and switches to the terminal B3 (power connection terminal I3). After that, if an abnormality is detected, the control unit 7 stops the motor or reduces the rotation speed.

  The automatic voltage switching according to the state of the drive unit 3 may be used in combination with the manual voltage switching by the voltage operation unit 16. Further, a preferable voltage may be displayed to the user according to the state of the driving unit 3, and the user may switch the voltage with the voltage operation unit 16 according to this display.

  As the battery pack 2 from which a plurality of voltages can be taken out, various connection can be conceived with respect to the connection of the battery cells. However, the battery pack 2 shown in FIGS. 1 and 7, that is, a plurality of battery cells C1, C2, C3 connected in series. In the case where the terminals B1 and B2 are drawn from the intermediate tap, it is not necessary to add a new battery cell to the conventional battery pack 2 that can extract only a single voltage. Nevertheless, the battery pack 2 from which a plurality of voltages can be taken out can be obtained at low cost.

  As for the connection of the battery cells in the battery pack 2, as shown in FIG. 13, the assembled battery in which the battery cells C1 to C3 are connected in series, the assembled battery 2 in which the battery cells C4 and C5 are connected in series, and the battery cell It is also possible to use three sets of batteries composed only of C6 and connect the terminals B3, B2 and B1 to these three sets of batteries. Of course, it may be other than the illustrated example, and any battery pack 2 capable of outputting a plurality of different voltages can be applied to the present invention.

DESCRIPTION OF SYMBOLS 1 Tool main body 2 Battery pack 3 Drive part 4 Detection part 5 Switching part 6 Operation part 7 Control part 8 Control power supply part 9 Voltage switching part

Claims (5)

  A power tool comprising a battery pack containing an assembled battery to which a plurality of secondary batteries are connected, and a tool body having a drive unit that operates using the battery pack as a power source, and the battery pack outputs different voltages. A power tool comprising: a plurality of terminals capable of performing the operation, wherein the tool body includes a voltage switching unit that selects a voltage supplied to the driving unit through the terminals of the battery pack.   The tool body includes a plurality of power connection terminals that are respectively connected to a plurality of terminals in the battery pack, and the voltage switching unit turns on and off the connection between the plurality of power connection terminals and the drive unit. The power tool according to claim 1, wherein the power tool is a switch.   The tool body includes a power connection terminal that is selectively connected to a plurality of terminals in the battery pack, and the voltage switching unit is a position changing mechanism for the selection of the power connection terminal. The power tool according to claim 1, wherein   The electric power tool according to any one of claims 1 to 3, wherein the tool body includes a voltage operation unit, and the voltage switching unit switches the voltage in accordance with an operation of the voltage operation unit.   The tool body includes a detection unit that detects the state of the drive unit, and a control unit that causes the voltage switching unit to switch the voltage in accordance with the state detected by the detection unit. Item 5. The electric tool according to any one of Items 1 to 4.

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