JP6060821B2 - Electric tool - Google Patents

Description

  The present invention relates to an electric tool that can prevent a fuse from being blown out due to heat generation and a failure of an electronic component.

  Conventionally, an electric tool in which a fuse is mounted in a battery pack or a tool housing has been put to practical use. In such power tools, the fuse is blown when an abnormal current flows when a mechanical component or electronic component fails, so that power supply is stopped before ignition or smoke occurs (for example, patents) Reference 1).

JP2011-140108A

  The capacity of the fuse mounted on the electric tool as described above is set to a current value at which the secondary battery can be discharged in order to protect the secondary battery. However, with tools that have a large load current and are used near the rated capacity of the fuse (for example, charging circular saws and charging screw tighteners), normal operation or overload operation that is assumed for use (locking during disconnection, Despite the operation of tightening the floating screw), the same operation is repeated in a short time, so that the temperature of the fuse mounted in the battery pack or tool housing rises, and the fuse is fused by heat accumulation. There was a possibility that. In addition, there is a possibility that an electronic component such as an FET may break down due to heat generation.

  In addition, as a method of preventing the fusing of the fuse and the failure of the electronic component, (1) a method of limiting the operating current of the tool so that the operating current of the tool does not exceed the rated current of the fuse or FET, (2 ) A method to prevent the tool operating current from exceeding the rated current of the fuse or FET by increasing the power supply voltage, or (3) a method to stop the tool by detecting the temperature of the fuse or FET, etc. .

  However, when the operating current is limited as in (1), the maximum torque is limited, so that there is a problem that the performance of the electric tool is limited.

  Further, when the power supply voltage is increased as in (2), it is necessary to increase the size of the battery pack and the like, leading to a problem of increasing the size and weight of the tool.

  Further, when the temperature of the fuse or FET is detected as in (3), it is necessary to add a part for temperature detection, which leads to a problem that the substrate is increased in size and cost.

  Therefore, the present invention can prevent fusing of the fuse and failure of the electronic parts, and the torque must be limited, the battery pack must be enlarged, or a part for temperature detection must be added. It is an object of the present invention to provide an electric tool that does not cause such a problem.

  The present invention has been made to solve the above-described problems, and is characterized by the following.

(Claim 1)
The invention described in claim 1 is characterized by the following points.
That is, the electric tool according to claim 1 is an electric tool equipped with an electronic component, and a motor, a switch for turning on / off power supply to the motor, and a current value supplied to the motor A current detection unit that samples at a predetermined interval, an arithmetic processing unit that calculates a determination value using a current value sampled by the current detection unit and an elapsed time since the current detection unit started sampling, A comparison processing unit that determines the necessity of cooling processing by comparing the determination value calculated by the arithmetic processing unit with a predetermined threshold, and the switch when the comparison processing unit determines that cooling processing is necessary And a cooling processing unit that executes the cooling process while disabling the operation in a certain period of time.

(Claim 2)
The invention described in claim 2 has the following features in addition to the features of the invention described in claim 1 described above.
That is, a cooling time setting unit that sets an execution time of the cooling process is provided, and the execution time of the cooling process set in the cooling time setting unit is used by the arithmetic processing unit for calculating the determination value. Features.

(Claim 3)
The invention described in claim 3 is characterized by the following points in addition to the characteristics of the invention described in claim 1 or 2.
That is, a reset processing unit that resets a sampling result of the current detection unit is provided.

  The invention according to claim 1 is as described above, and an arithmetic processing unit that calculates a determination value using the current value sampled by the current detection unit and the elapsed time since the current detection unit started sampling. A comparison processing unit that determines the necessity of the cooling process by comparing the determination value calculated by the calculation processing unit with a predetermined threshold, and a case where the comparison processing unit determines that the cooling process is necessary. A cooling processing unit that disables the operation of the switch for a certain period of time and executes a cooling process.

  Therefore, when the value accumulated using the current value and time exceeds a predetermined threshold value, the operation of the switch is disabled for a certain time and the cooling process is executed. The electronic parts such as can be cooled. Therefore, even if the temperature of an electronic component rises by repeating high-load operations in a short time, the necessity of cooling processing is reasonably determined by the current value and time, and cooling processing is executed as necessary. As a result, the electronic component is cooled, and the fuse can be prevented from being blown out or the electronic component can be prevented from malfunctioning.

  In addition, fuse fuses and electronic component failures can be prevented without limiting the operating current, so discharge can be maximized within a range where fuse fuses and electronic component failures do not occur. The tool performance can be maximized.

  In addition, since it is not necessary to increase the power supply voltage, there is no need to increase the size of the battery pack or the like, and the problem of increasing the size and weight of the tool does not occur.

  Further, since it is not necessary to detect the temperature of the fuse or FET, it is not necessary to add a temperature detection component, and problems such as an increase in the size and cost of the substrate do not occur.

  In addition, the invention according to claim 2 is as described above, and includes a cooling time setting unit that sets the execution time of the cooling process. Therefore, the execution time of the cooling process is changed according to the use environment of the user. The operability and performance can be adjusted. In addition, since the execution time of the cooling process set in the cooling time setting unit is used for the calculation of the determination value by the arithmetic processing unit, the execution time of the cooling process is set short. However, it is possible to effectively prevent fuses from being blown out or electronic components from being damaged.

  Specifically, if the execution time of the cooling process is set to be long, the calculation result of the arithmetic processing unit can be set to a relatively small value by changing the execution time of the cooling process. The determination value calculated by the processing unit is unlikely to reach a predetermined threshold value. In other words, the time until the cooling process is executed can be increased in exchange for the longer execution time of the cooling process, so that the continuous operation time of the electric tool is increased when performing a heavy work. The performance of the power tool can be improved. When the judgment value reaches a predetermined threshold, the electronic component is sufficiently cooled by providing a long cooling time, so that even if the continuous operation time is extended, the fuse may be blown out or the electronic component may fail. It can be effectively prevented.

  On the contrary, if the execution time of the cooling process is set to be short, if the calculation result of the arithmetic processing unit becomes a relatively large value by changing the execution time of the cooling process, the arithmetic processing unit It becomes easy for the determination value calculated by to reach a predetermined threshold value. In other words, the time until the cooling process is executed is shortened in exchange for the shortening of the execution time of the cooling process. Can work.

  The invention according to claim 3 is as described above, and includes a reset processing unit that resets a sampling result of the current detection unit. Therefore, when the arithmetic processing unit is realized by software, an integrated value of the sampling values Can be prevented from overflowing.

It is an external appearance perspective view of an electric tool. It is a block diagram at the time of implement | achieving a cooling process with software with the control apparatus incorporated in the tool main body. It is a block diagram at the time of implement | achieving a cooling process by software with the control apparatus incorporated in the battery pack. It is a flow figure at the time of realizing cooling processing with software. When the cooling process is realized by software, (a) a calculation formula for the first determination value and (b) a calculation formula for the second determination value. It is a block diagram at the time of implement | achieving a cooling process with hardware with the circuit arrange | positioned in the tool main body. It is a block diagram at the time of implement | achieving a cooling process with hardware with the circuit arrange | positioned in the battery pack. It is a flow figure at the time of realizing cooling processing with hardware. It is a calculation formula of a judgment value when cooling processing is realized by hardware.

  The embodiment of the present invention will be described with reference to the drawings, taking a connecting screw screw tightening machine 10 as an example of an electric tool.

  The connecting screw screw tightening machine 10 according to the present embodiment uses a connecting screw 16 in which a plurality of screws are connected by a connecting band, and as shown in FIG. 1, a nose formed at the tip of a tool body 11. A screw is driven from the portion 14 into the workpiece.

  The connecting screw screw tightening machine 10 is a rechargeable electric tool that operates using a rechargeable battery pack 15 that is detachably mounted on a mounting portion 12 formed at the rear end of the tool body 11 as a power source. .

  Although not particularly shown, the above-described nose portion 14 is provided with a driver bit, and when the trigger 13 of the tool body 11 is pulled, the motor 23 rotates using the battery pack 15 as a power source. When the nose portion 14 is pressed against the material to be driven while the motor 23 is rotated, the nose portion 14 is pushed in, the driver bit strikes the screw held in the nose portion 14, and the driver bit is pushed in. Since the rotation of the motor 23 is transmitted to the pushed driver bit, the driver bit is rotated and the screw is tightened to be driven into the driven material.

  FIG. 2 is a block diagram showing the internal structure of the connecting screw tightening machine 10. As shown in the block diagram, when the tool body 11 and the battery pack 15 are electrically connected, power is supplied from the battery pack 15 to the tool body 11 so that the motor 23 can rotate. Is formed. Inside the tool body 11, a fuse 21, which is an electronic component, a trigger switch 22 as a switch, a motor 23, a switching element 24, and a current detection unit 25 are electrically connected in series.

  The trigger switch 22 is for turning on / off the power supply to the motor 23, and the electric circuit is closed so that the power supply to the motor 23 is started when the trigger 13 is pulled. It is what.

  The switching element 24 is composed of, for example, an FET and cuts an electric circuit in order to execute a cooling process described later. The switching element 24 closes the electric circuit when the cooling process is not performed, and opens the electric circuit when the cooling process is being performed. Thereby, during the cooling process, even if the trigger switch 22 is operated, the power supply to the motor 23 is not performed.

The current detector 25 samples a current value supplied to the motor 23 at a predetermined interval (for example, every 100 ms). The current detection unit 25 samples a current value at a predetermined interval using a known structure such as a current detection circuit, and transmits the sampled current value to the control device 30 described later.
Further, the tool body 11 incorporates a control device 30 for controlling the switching element 24 and the like described above.

  Although not specifically shown, the control device 30 is configured around a CPU and includes a ROM, a RAM, and the like. The CPU reads a program stored in the ROM, and functions as an integration processing unit 31, a comparison processing unit 32, a cooling processing unit 33, a cooling time setting unit 34, and a reset processing unit 35 as an example of an arithmetic processing unit. It is configured as follows.

  The integration processing unit 31 calculates a determination value based on input data from the current detection unit 25. As shown in FIGS. 5A and 5B, the integration processing unit 31 according to the present embodiment calculates two types of determination values.

  FIG. 5A is an equation for calculating a first determination value for determining the necessity of the cooling process. In this equation, the current values Is1 to IsN sampled by the current detection unit 25 (N is the number of samplings. In the case of the first sampling, IsN = Is1, in the case of the second sampling, IsN = Is2), the current detection unit 25 The integration processing unit 31 is substituted by substituting the sampling cycle Ts (for example, 100 ms), the elapsed time since the current detection unit 25 started sampling (sampling number N × sampling cycle Ts), and the cooling processing execution time Tc. Calculates the first determination value.

  FIG. 5B is an equation for calculating a second determination value for determining the necessity of reset processing. Integration by substituting into this equation the current values Is1 to IsN sampled by the current detection unit 25, the sampling period Ts of the current detection unit 25, and the elapsed time since the current detection unit 25 started sampling. The processing unit 31 calculates the second determination value.

  For convenience, the equations in FIGS. 5A and 5B are equations when the number of samplings is three or more. When the number of samplings is 1, since there is no more than Is2, the square root numerator on the right side is “(Is1 ^ 2 × Ts)”. When the number of times of sampling is two, the square root numerator on the right side is “(Is1 ^ 2 × Ts) + (Is2 ^ 2 × Ts)”.

  The comparison processing unit 32 compares the first determination value calculated by the integration processing unit 31 with a predetermined threshold value to determine the necessity of the cooling process, and the second determination calculated by the integration processing unit 31. The necessity of the reset process is determined by comparing the value with a predetermined threshold value. Specifically, when the first determination value is equal to or greater than a predetermined threshold, a signal instructing the cooling processing unit 33 to execute the cooling processing is output. When the second determination value is less than the predetermined threshold value, a signal instructing the reset processing unit 35 to execute the reset process is output.

  The predetermined threshold value is set in consideration of the rated capacity of the fuse 21. Specifically, a value obtained by multiplying the rated capacity of the fuse 21 by the derating coefficient of the environmental temperature and the total energization time is set.

  When the comparison processing unit 32 determines that the cooling process is necessary, the cooling processing unit 33 disables the operation of the trigger switch 22 for a predetermined time and executes the cooling process. Specifically, when a signal instructing execution of the cooling process is received from the comparison processing unit 32, the switching element 24 is operated to open the circuit. Note that the time for which the circuit is opened (cooling execution time) is set by a cooling time setting unit 34 described later.

  The cooling time setting unit 34 is for setting the execution time of the cooling process. The cooling time setting unit 34 stores the execution time of the cooling process designated by the user (for example, 0.5 seconds to 2.5 seconds) in a memory or the like. The user interface for the user to specify the execution time of the cooling process is not particularly shown, but may be configured by known operation means such as buttons, memory card insertion, or wireless data communication. The cooling processing execution time stored in the memory by the cooling time setting unit 34 is read and used by the cooling processing unit 33 described above. That is, when executing the cooling process, the cooling processing unit 33 executes the cooling process until the execution time of the cooling process set by the cooling time setting unit 34 elapses.

  The reset processing unit 35 resets the sampling result of the current detection unit 25 when the comparison processing unit 32 determines that the reset processing is necessary. Specifically, when the signal instructing execution of the reset process is received from the comparison processing unit 32, the data used by the integration processing unit 31 for the calculation is reset. By executing this reset process, the sampling current value data accumulated for use in the calculation of the integration processing unit 31 is discarded, and the value of the number of times of sampling used for the calculation of the integration processing unit 31 is also zero. It is initialized to. Thus, by resetting the data at a timing that does not affect the user's work, the problem that the accumulated value overflows beyond the variable storage area can be avoided.

In the above description, the electronic component (fuse 21) to be protected is built in the tool body 11. However, as shown in FIG. 3, the electronic component (fuse 21) to be protected is a battery pack. 15 may be incorporated. The switching element 24, the current detection unit 25, and the control device 30 (the integration processing unit 31, the comparison processing unit 32, the cooling processing unit 33, the cooling time setting unit 34, and the reset processing unit 35) for executing the cooling process are batteries. It may be built in the pack 15.
FIG. 4 is a flowchart for explaining the cooling process.

  As shown in FIG. 4, first, in step S <b> 100, the current detection unit 25 samples a current value flowing on the circuit at a predetermined sampling period, and outputs it to the integration processing unit 31. Then, the process proceeds to step S101.

  In step S <b> 101, the integration processing unit 31 calculates the first determination value and the second determination value based on the sampling current value, and outputs the calculation result to the comparison processing unit 32. Then, the process proceeds to step S102.

  In step S102, the comparison processing unit 32 compares the first determination value with a predetermined threshold value. If the first determination value is greater than or equal to the predetermined threshold value, the process proceeds to step S103. On the other hand, if the first determination value is less than the predetermined threshold value, the process proceeds to step S104.

  When the process proceeds to step S103, the cooling processing unit 33 sets the switching element 24 to OFF and disables the trigger switch 22 until the execution time of the cooling process designated by the cooling time setting unit 34 has elapsed. As a result, the cooling process is executed, and control is performed so that the tool does not operate for a time sufficient to cool the fuse 21. Then, the process proceeds to step S104.

  In step S104, the comparison processing unit 32 compares the second determination value with a predetermined threshold value. If the second determination value is less than the predetermined threshold value, the process proceeds to step S105. On the other hand, if the second determination value is greater than or equal to the predetermined threshold value, the process returns to step S100.

  When the process proceeds to step S105, the reset processing unit 35 resets the data used by the integration processing unit 31 for calculation. Then, the process returns to step S100.

  According to such an aspect, when the first determination value integrated using the current value and time sampled by the integration processing unit 31 exceeds a predetermined threshold, the operation of the trigger switch 22 is disabled for a certain period of time. Since the cooling process is executed, the electronic component such as the fuse 21 can be cooled by using the cooling process time. Therefore, even if the temperature of an electronic component rises by repeating high-load operations in a short time, the necessity of cooling processing is reasonably determined by the current value and time, and cooling processing is executed as necessary. As a result, the electronic component is cooled, and it is possible to prevent the fuse 21 from being blown out erroneously and the failure of the electronic component (such as FET).

  In addition, since the fuse 21 can be prevented from being blown out or the electronic component can be prevented from malfunctioning without limiting the operating current, the discharge can be maximized within the range where the fuse 21 is not blown out or the electronic component is not broken. The power tool performance can be maximized.

  Further, since it is not necessary to increase the power supply voltage, there is no need to increase the size of the battery pack 15 and the like, and problems such as increase in the size and weight of the tool do not occur.

  Further, since it is not necessary to detect the temperature of the fuse 21 or the FET, it is not necessary to add a component for temperature detection, and problems such as an increase in the size of the substrate and an increase in cost do not occur.

  In addition, since the cooling time setting unit 34 that sets the execution time of the cooling process is provided, the execution time and the performance can be adjusted by changing the execution time of the cooling process according to the use environment of the user. In addition, since the execution time of the cooling process set in the cooling time setting unit 34 is used for the calculation of the first determination value by the integration processing unit 31, the execution time of the cooling process is set short. Even in this case, it is possible to effectively prevent the fuse 21 from being blown out or the electronic component from being broken.

  Specifically, when the execution time of the cooling process is set to be long, the calculation result of the integration processing unit 31 becomes a relatively small value due to the change of the execution time of the cooling process. It becomes difficult for the determination value calculated by 31 to reach a predetermined threshold value. In other words, the time until the cooling process is executed can be increased in exchange for the longer execution time of the cooling process, so that the continuous operation time of the electric tool is increased when performing a heavy work. The performance of the power tool can be improved. When the determination value reaches a predetermined threshold value, the electronic component is sufficiently cooled by providing a long cooling time. Therefore, even when the continuous operation time is increased, the fuse 21 is erroneously blown or the electronic component is broken. Can be effectively prevented.

  On the contrary, when the execution time of the cooling process is set short, the calculation result of the integration processing unit 31 becomes a relatively large value due to the change of the execution time of the cooling process. The calculated determination value easily reaches a predetermined threshold value. In other words, the time until the cooling process is executed is shortened in exchange for the shortening of the execution time of the cooling process. Can work.

  Further, since the reset processing unit 35 that resets the sampling result of the current detection unit 25 is provided, it is possible to prevent a problem that the integrated value of the sampling value overflows when the integration processing unit 31 is realized by software.

  In the above-described embodiment, the method for realizing the cooling process by software has been described. However, the present invention is not limited to this, and the cooling process can also be realized by hardware.

  That is, as shown in FIG. 6, the integration processing unit 31, the comparison processing unit 32, and the cooling processing unit 33 may be configured by circuits. In this case, an integration processing unit 31 (integration circuit), a comparison processing unit 32 (comparison circuit), and a cooling processing unit 33 (timer circuit) may be connected to the subsequent stage of the current detection unit 25. Moreover, what is necessary is just to control ON / OFF of the switching element 24 by connecting the output of the cooling process part 33 to the switching element 24. FIG. The calculation of the integration processing unit 31 is performed based on the formula shown in FIG.

In the above description, the electronic component (fuse 21) to be protected is built in the tool body 11. However, as shown in FIG. 7, the electronic component (fuse 21) to be protected is a battery pack. 15 may be incorporated. And the switching element 24 for performing a cooling process, the electric current detection part 25, the integration process part 31, the comparison process part 32, and the cooling process part 33 may be incorporated in the battery pack 15. FIG.
FIG. 8 is a flowchart for explaining the cooling process when the cooling process is realized by hardware.

  As shown in FIG. 8, first, in step S <b> 200, the current detection unit 25 samples a current value flowing on the circuit at a predetermined sampling period, converts it into a voltage, and outputs it to the integration processing unit 31. Then, the process proceeds to step S201.

  In step S <b> 201, the integration processing unit 31 calculates a determination value based on the sampling voltage value, and outputs the calculation result to the comparison processing unit 32. Then, the process proceeds to step S202.

  In step S202, the comparison processing unit 32 compares the determination value with a predetermined threshold value. If the determination value is greater than or equal to the predetermined threshold value, the process proceeds to step S203. On the other hand, if the determination value is less than the predetermined threshold, the process returns to step S200.

  When the process proceeds to step S203, the cooling processing unit 33 sets the switching element 24 to OFF and disables the trigger switch 22 until a predetermined cooling processing execution time elapses. As a result, the cooling process is executed, and control is performed so that the tool does not operate for a time sufficient to cool the fuse 21. Then, the process returns to step S200.

  As described above, even when the cooling process is realized by hardware, the same effect as when the cooling process is realized by software can be obtained.

  In this embodiment, the integration processing unit 31 performs integration as an example of the arithmetic processing unit. However, a differential processing, a peak value, an effective value, or the like may be used.

10 Connection screw tightening machine (electric tool)
DESCRIPTION OF SYMBOLS 11 Tool main body 12 Mounting part 13 Trigger 14 Nose part 15 Battery pack 15a Battery cell 16 Connection screw 21 Fuse (electronic component)
22 Trigger switch 23 Motor 24 Switching element 25 Current detection unit 30 Control device 31 Integration processing unit (arithmetic processing unit)
32 Comparison processing unit 33 Cooling processing unit 34 Cooling time setting unit 35 Reset processing unit

Claims (3)

An electric tool equipped with electronic components,
A motor,
A switch for turning on and off the power supply to the motor;
A current detector for sampling a current value supplied to the motor at a predetermined interval;
An arithmetic processing unit that calculates a determination value using a current value sampled by the current detection unit and an elapsed time after the current detection unit starts sampling;
A comparison processing unit that determines the necessity of cooling processing by comparing the determination value calculated by the calculation processing unit with a predetermined threshold;
A cooling processing unit that executes the cooling process by disabling the operation of the switch for a predetermined time when it is determined by the comparison processing unit that the cooling process is necessary;
An electric tool comprising: A cooling time setting unit for setting an execution time of the cooling process;
The power tool according to claim 1, wherein the execution time of the cooling process set in the cooling time setting unit is used by the calculation processing unit to calculate the determination value.   The power tool according to claim 1, further comprising a reset processing unit that resets a sampling result of the current detection unit.

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