TWI690396B - Electric tool and electric tool control circuit and control method - Google Patents

Abstract

The object of the present invention is to prevent the damage of the setting data and the like stored in the information memory means due to the counter electromotive force generated by the electric motor. The solution is: the electric screwdriver includes: an electric motor; a Hall sensor, which detects the rotation of the electric motor and then transmits the rotation detection signal; and a memory, which stores setting data related to the control of the electric motor. When a voltage is applied to the control circuit of the electric screwdriver to start the control circuit (S100), when the rotation of the electric motor is detected by the Hall sensor and the electric motor is rotating, the memory is not accessed (S104). If the time when the electric motor is stopped is more than a predetermined reference time (100 ms), access to the memory is allowed (S106, S108).

Description

Electric tool and electric tool control circuit and control method

The present invention relates to a control circuit for an electric tool provided with an electric motor, and a control method of the electric tool.

For example, Patent Document 1 discloses an electric screwdriver that rotates and drives a screwdriver bit by an electric motor to perform a screw locking operation. In this type of electric screwdriver, in general, the user can change the setting of the tightening torque or the tightening time in accordance with the type of screw or the member to which the screw is locked. Therefore, the electric screwdriver is provided with an information memory means for pre-recording the setting data. In most cases, this information memory means consists of semiconductor memory that can be read and written. When an electric screwdriver is connected to an external power source and a voltage is applied to the control circuit of the electric screwdriver, the control circuit automatically starts, and the control conditions of the electric screwdriver are set based on the initialization and setting data of the electric screwdriver. When this initial setting is completed, the screw lock operation can be performed according to the user's operation.

In an electric tool having an electric motor like the above-mentioned electric screwdriver, even if the electric tool is not connected to an external power source, if the electric motor is rotated by an external force, a back electromotive force is generated, and a voltage is applied to the control circuit. In this way, when a huge voltage is applied to the control circuit to activate the control circuit, the control circuit may be activated and the initialization or control conditions of the electric tool may be set. Since the back electromotive force of the electric motor is unstable and is temporarily generated, the back electromotive force cannot stably supply power to the control circuit. Therefore, under normal circumstances, even if the control circuit is temporarily activated, it will immediately stop. Therefore, if the control circuit is activated by the counter electromotive force, the control circuit may stop in the middle of accessing information storage means such as a memory for recording setting data. In this way, if the control circuit suddenly stops while accessing the memory, there is a possibility that the data stored in the information memory means may be damaged.

In order to prevent data damage, a diode is placed between the electric motor and the control circuit so that the current accompanying the back-EMF of the electric motor does not flow to the control circuit, and the control circuit will not start due to the back-EMF. [Prior Technical Literature] [Patent Literature]

[Patent Literature 1] International Publication No. 2017/170648

[Problems to be solved by the invention]

For example, in the above-mentioned electric screwdriver, since the tightening torque of the screw is roughly proportional to the magnitude of the current flowing to the electric motor, if the locking torque is increased, a large current will flow to the electric motor. The diode used to prevent the back electromotive force from being applied to the control circuit must be a large-capacity diode that can withstand such a large current, but because this diode is not easy to obtain or can be obtained but the size is too large, it must be increased The big electric screwdriver itself.

Therefore, the object of the present invention is to provide a control circuit for an electric tool without using additional current control circuit components such as diodes to prevent damage to the data stored in the information memory means due to the back EMF generated by the electric motor . In addition, an object of the present invention is to provide an electric tool provided with such a control circuit and a control method of an electric tool capable of preventing data damage.

That is, the present invention provides a control circuit for an electric tool, the electric tool having: an electric motor; a rotation detection means that detects the rotation of the electric motor and transmits a rotation detection signal; and an information memory means, which Save the setting data related to the control of the electric motor; when the voltage is applied to the control circuit, the control circuit determines whether the electric motor is rotating based on the rotation detection signal. When the electric motor is rotating, the information is not Memory means access.

In this control circuit, when a voltage is applied to the control circuit, the information storage means cannot be accessed when the electric motor is rotating. At the time when a voltage is applied to the control circuit, when the electric motor is rotating, the electric motor rotates by an external force to generate a counter electromotive force, and applying the voltage to the control circuit by the counter electromotive force has a high possibility of starting the control circuit. In this control circuit, when the possibility of starting the control circuit by the back electromotive force is high, the information memory means is not accessed. By this, it is possible to prevent the control circuit from temporarily starting due to the back electromotive force of the electric motor and then accessing the control circuit The control circuit stops during the information memory means, which results in damage to the setting data and other data saved in the information memory means.

Preferably, when it is determined that the rotation stop time of the electric motor is greater than or equal to a predetermined reference time, access to the information storage means is permitted.

With this setting, the state where the rotation of the electric motor has stopped can be more surely detected, and the information memory means can be accessed only in a safer state. As a means for detecting rotation, various elements such as Hall sensors or encoders are considered, including those that emit a signal only when the rotation shaft of the electric motor passes a predetermined rotation position. In the case of using this method, the signal indicating the rotation of the electric motor is transmitted only in the form of pulses. Therefore, even if the electric motor is rotating, there will be a time when the control circuit does not accept the signal. According to the above-mentioned configuration, even in this case, it is possible to more accurately determine that the rotation of the electric motor is stopped, and to more surely prevent the information storage means from being mistakenly determined that the electric motor has stopped even if the electric motor is rotating.

Preferably, when the stop time is more than the reference time, the information storage means can be accessed and the setting data can be read, and then the control conditions of the electric tool can be set based on the read setting data.

Moreover, once access to the information memory means is permitted, regardless of whether the electric motor rotates or not, the state where access to the information memory means is allowed to be maintained can be maintained.

Specifically, the information memory means can be a readable and writable memory.

The present invention also provides an electric tool, which includes: an electric motor; Rotation detection means, which detects the rotation of the electric motor and transmits a rotation detection signal; information memory means, which stores setting data related to the control of the electric motor; and any of the control circuits described above.

The invention also provides a control method of an electric tool, the electric tool is provided with: an electric motor; a rotation detection means, which detects the rotation of the electric motor and then transmits a rotation detection signal; an information memory means, which stores the Control-related setting data; and a control circuit, the control method includes: the step of detecting the rotation of the electric motor by the rotation detection means when a voltage is applied to the control circuit; and when the electric motor is rotating, it is wrong The steps of accessing the information memory means.

The method may further include the steps of: calculating a time at which the rotation of the electric motor stops; when the stop time is greater than the reference time, accessing the information memory means and then reading the setting data; based on the reading The step of setting the control conditions of the electric tool according to the setting data; and after the setting step, regardless of whether the electric motor rotates or not, it is set to allow access to the information memory means.

Hereinafter, an embodiment of the electric power tool of the present invention will be described based on additional drawings.

The electric screwdriver (power tool) 100 according to the first embodiment of the present invention includes a tool housing 110, an electric motor 112 built in the tool housing 110, and a drill holder 114 as shown in FIGS. 1 and 2. , Which is rotationally driven by the electric motor 112. A driver bit 116 appropriately selected in accordance with the target screw is detachably attached to the bit holder 114. The tool housing 110 is provided with: an input interface 122 having a display portion 118 and an input button 120; and a power cord 124 for connecting the electric screwdriver 100 to an external power source 123. Also provided in the tool housing 110 are: a motor drive circuit 126 for controlling the driving of the electric motor 112; a control circuit 128 for controlling the entire electric screwdriver 100; a Hall sensor 130 which detects the electric motor 112. Rotating position of the rotor; and readable and writable non-volatile semiconductor memory (information memory means) 132 where setting data is saved. Further, although not shown in the figure, there is a program memory or a data memory and a register memory used when the control circuit 128 executes the control program by storing the control program in advance at the manufacturing stage. Except for program update and other special conditions, program memory is used as a dedicated memory for reading. Basically, data is not written or deleted by users. The data memory and the register memory are only used in the execution of the control program, and are volatile memories that delete internal data while the power is stopped.

Among them, "setting data" refers to data mainly used to perform settings related to the control of the electric motor 112, for example, the data is the setting torque during the setting screw lock operation, the rotation time of the electric motor 112, the screw performing the lock The number, the qualification criteria for judging when the screw locking operation has been completed normally, etc. The setting data can be arbitrarily changed by the user by operating the input interface 122 or transmitting data by an external device such as a computer. The changed setting data is written to the memory 132 and saved.

The Hall sensor 130 is fixed to the stator side of the electric motor 112, and detects the rotation position of the rotor by detecting the magnetic field generated by the magnet set in the rotor. Based on the rotation position of the rotor detected by the Hall sensor 130, the timing of energization of each coil of the stator is controlled, thereby smoothly rotating the rotor. In the electric screwdriver 100, the control circuit 128 receives the output signal transmitted from the Hall sensor 130, and then determines whether the electric motor 112 rotates based on the output signal. In other words, the Hall sensor 130 functions as a rotation detection means for detecting the rotation of the electric motor 112. The control circuit 128 determines that the rotation of the electric motor 112 has stopped when the output signal (rotation detection signal) does not change, and determines that the electric motor 112 is rotating when the output signal changes.

As a rotation detection means for detecting the rotation of the electric motor 112, any sensor other than the Hall sensor 130 can be used. For example, FIG. 3 shows an embodiment in which a resistance element 136 is connected to each wiring 134 connected to each coil of the electric motor 112. In this embodiment, by detecting the voltage change of each resistance element 136, the current flowing through the wiring 134 is detected. When a current flows through the wiring 134, it is considered to be either when the electric motor 112 is rotationally driven by supplying electric power to the electric motor 112 based on a control program, or when the electric motor 112 is rotated by an external force to generate a back electromotive force. In short, there is a high possibility that the electric motor 112 is rotating when the wiring 134 generates current. Therefore, it is possible to detect whether the electric motor 112 rotates by detecting the voltage change between the resistance elements 136. In addition, in the illustrated example, the electric motor 112 is a three-phase motor, but it may be a single-phase motor. Alternatively, a torque sensor may be provided on the rotating shaft of the electric motor 112 or the rotating mechanism for transmitting power from the rotating shaft to the driver bit 116, and when the torque sensor detects a change in the torque, the electric motor 112 is determined Is spinning. Further, rotation detection can also be performed by the encoder. The rotation detection means of the present invention can use various sensors as described above, and any means based on any other detection principle can be used as long as it does not deviate from the purpose of the present invention.

The operation (control method) when the electric screwdriver 100 is started will be described below with reference to FIG. 4. When a voltage is applied to the control circuit 128, the control circuit 128 is activated and the initial setting is performed. Specifically, when the control circuit 128 is activated (S100), initialization is first performed (S102). Here, initialization refers to, for example, setting the control program to be read from the program memory, or storing necessary data in the data memory or the register memory, and performing the operation of controlling the state of the program. Then, based on the rotation detection signal transmitted from the Hall sensor 130, it is determined whether the electric motor 112 is rotating (S104). Specifically, if there is no change in the rotation detection signal, it is determined that the electric motor 112 has stopped, and if there is a change, it is determined that the electric motor 112 is rotating. When the electric motor 112 is rotating, it waits until the electric motor 112 stops. When the electric motor 112 has stopped, the time that the electric motor 112 has stopped is calculated (S106), and the standby time is reached until the stop time reaches a predetermined reference time (100 ms in this embodiment). If the stop time is equal to or longer than the reference time, access to the memory 132 is started, setting data is read (S108), and the control conditions of the electric screwdriver 100 are set based on the read setting data (S110). At this time, data indicating the number of activations is written to the memory 132. If the setting is normally completed (S112), a series of initial settings are completed and the screw locking operation by the user's operation can be performed (S114).

In the electric screwdriver 100, if a voltage is applied to the control circuit 128 as described above, the initial setting is automatically performed. The timing of applying a voltage to the control circuit 128 is usually when the electric screwdriver 100 is connected to an external power supply 123 and electric power is supplied from the external power supply 123. At this time, normally, the electric motor 112 has not yet rotated, so the memory 132 is allowed to be accessed according to the flowchart of FIG. In addition, even when the electric screwdriver 100 is not connected to the external power supply 123, if the screwdriver bit 116 is rotated manually or the like, and the electric motor 112 is rotated by an external force, the electric motor 112 generates a counter electromotive force, and current flows from the electric The state where the motor 112 flows to the control circuit 128 and a voltage is applied to the control circuit 128. At this time, if a voltage level required for activation is applied to the control circuit 128, the control circuit 128 will be activated. Since the back electromotive force of the electric motor 112 is usually generated for only a few seconds or less, even if the control circuit 128 is started, it will immediately stop. Therefore, if the control circuit 128 is temporarily activated due to the counter electromotive force, access to the memory 132 is more likely to cause the control circuit 128 to stop when power supply is stopped during access. During access to the memory 132, especially during writing of data to the memory 132, if the control circuit 128 is stopped, there is a possibility that data such as setting data stored in the memory 132 may be damaged. In the electric screwdriver 100, as described above, the rotation of the electric motor 112 is monitored by the Hall sensor 130, and when the electric motor 112 is rotating, it waits until the rotation stops. Therefore, due to the counter electromotive force generated by the rotation of the electric motor 112, the memory 132 cannot be accessed when the control circuit 128 is activated. That is to say, in the electric screwdriver 100, the memory 132 can be accessed only when power is stably supplied from the external power supply 123, so that the control circuit 128 stops when the control circuit 128 accesses the memory 132, which can reduce The possibility of damage to the setting data in the memory 132. Moreover, the program memory, data memory, and register memory are also accessed when they are started by the back electromotive force in the initialization project (S102), but the program memory is dedicated to reading and data writing. It will not be executed at startup, so the possibility of data damage due to the stop of the control circuit 128 is low, and the data in the data memory and the register memory will be deleted when the power supply is stopped, so even If the data stored in the memory is damaged, it will not be a problem.

In the electric screwdriver 100, the access is not allowed immediately after it is determined that the rotation of the electric motor 112 stops, that is, the memory 132 is allowed to be accessed, but after the electric motor 112 is stopped for a predetermined reference time (100 ms) or more. It is also considered that when the electric motor is rotated by an external force, the rotation of the electric motor does not continue, but is temporarily stopped and then immediately rotated. Also, as described above, various means can be adopted as the rotation detection means, but it includes a means for transmitting a signal only when the rotor is at a predetermined rotation position. In the case of using this rotation detection means, even if the rotation detection means is not transmitted In fact, the electric motor 112 may be rotating. By setting the above-mentioned prescribed reference time, it is possible to more surely judge that the electric motor 112 has stopped, and thereby, it is possible to more surely prevent access to the memory 132 when it is started due to back electromotive force.

Moreover, once the access to the memory 132 is allowed and the initial setting is completed, the power supply to the electric screwdriver 100 is highly likely to be performed by the stable external power supply 123, so during the access to the information storage means, the power The probability of a sudden supply stop is extremely low. Therefore, once access to the memory 132 is permitted, it will be in a state where access to the memory 132 is allowed at any point in time regardless of whether the electric motor 112 rotates or not, and this state is maintained.

The electric screwdriver 200 according to the second embodiment of the present invention is composed of an electric screwdriver body 202 and a controller 204 for controlling the electric screwdriver body 202 as shown in FIGS. 5 and 6. The electric screwdriver body 202 and the controller 204 are connected by a communication cable 206 via communication portions 238a, 238b provided therein, respectively. The power line 224 connected to the external power source 223 is provided on the side of the controller 204, and the power supply from the external power source 223 toward the electric screwdriver body 202 is executed from the controller 204 via the communication cable 206. In the tool housing 210 of the electric screwdriver body 202, as shown in FIG. 6, an electric motor 212, a motor drive circuit 226, and a Hall sensor 230 similar to the electric screwdriver 100 of the first embodiment are provided. The input interface 222 is provided on the side of the controller 204.

In the electric screwdriver 200, control circuits 228a and 228b are provided in the electric screwdriver body 202 and the controller 204, respectively. The two control circuits 228a and 228b communicate with each other via the communication cable 206, and the two control circuits 228a and 228b achieve the same function as the control circuit 128 of the first embodiment. Similarly, the electric screwdriver body 202 and the controller 204 are respectively provided with memories 232a and 232b, and the two memories 232a and 232b achieve the same function as the memory 132 of the first embodiment.

When a voltage is applied to the control circuits 228a and 228b, as shown in FIG. 7, the control circuits 228a and 228b will be activated respectively to perform the initial setting. Specifically, when the control circuit 228a on the side of the electric screwdriver body 202 is activated (S200), initialization is first performed (S202). Then, based on the rotation detection signal from the Hall sensor 230, it is determined whether the electric motor 212 is rotating (S204). When the electric motor 212 is not stopped, it stands by until the electric motor 212 is stopped. When the electric motor 212 has stopped, the time when the electric motor 212 has stopped is calculated (S206). The standby time until the stop time becomes a predetermined reference time (100 ms in this embodiment). If the stop time becomes more than the reference time, a normal start signal is transmitted to the control circuit 228b on the controller 204 side (S208).

After the control circuit 228b on the controller 204 side receives the normal start signal (S252) after starting (S250), it accesses the memory 232b to read the setting data (S254), and transfers the read setting data to the electric screwdriver The control circuit 228a on the side of the body 202 (S256). When the control circuit 228a on the side of the electric screwdriver body 202 receives the setting data (S210), the control conditions of the electric screwdriver 200 are set based on the received setting data (S212). At this time, setting data is written to the memory 232a. Then it is judged whether the setting has been completed normally (S214). If it has been completed normally, the OK signal is transmitted to the control circuit 228b on the controller 204 side (S216). If it has not been completed normally, the NG signal is transmitted to the controller 204 side. Control circuit 228b (S218). When the OK signal is transmitted, the initial setting on the side of the electric screwdriver body 202 is completed, and the screw locking operation can be performed (S220). When the control circuit 228b on the controller 204 side receives the OK signal (S258), it is in a state where the initial setting on the controller 204 side is completed and the screw locking operation can be performed (S260). In addition, when receiving the NG signal (S258), the memory 132 is accessed again, and the reading of the setting data (S254) is restarted. Even in this electric screwdriver 200, similar to the electric screwdriver 100 of the first embodiment, by monitoring whether the electric motor 212 is rotating when the control circuits 228a and 228b are started, it is not accessed when the back-EMF of the electric motor 212 is started. Memory 232a, 232b. This prevents the control circuits 228a and 228b from accessing the memories 232a and 232b to prevent damage to the setting data and other data in the memories 232a and 232b when the control circuits 228a and 228b stop.

Furthermore, in this embodiment, the control circuits 228a and 228b and the memories 232a and 232b are distributed and arranged in the electric screwdriver body 202 and the controller 204, but the arrangement method can be appropriately changed. In addition, the control circuits 228a, 228b or the memories 232a, 232b may be arranged together in either the electric screwdriver body 202 or the controller 204.

The embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. For example, in the above-mentioned embodiment, the present invention has been described using an electric screwdriver as an example, but it may be another type of electric tool that uses an electric motor such as a torque wrench or a grinder as a driving source. In addition, after the time when the rotation of the electric motor has stopped becomes more than a predetermined reference time, access to the memory is permitted, but the reference time can be arbitrarily changed. Also, for example, in the case of using a rotation detection means that can surely sense the rotation stop of the electric motor, etc., the reference time can be deleted and if it is determined that the rotation of the electric motor has stopped, access to the memory can be allowed immediately. As the information memory means for saving the setting data, in addition to the above-mentioned built-in semiconductor memory, a hard disk drive, a recordable medium such as a writable CD or DVD, and a removable USB memory can be used. means.

100‧‧‧Electric screwdriver (power tool) 110‧‧‧Tool housing 112‧‧‧Electric motor 114‧‧‧Drill holder 116‧‧‧driver bit 118‧‧‧ Display 120‧‧‧Enter button 122‧‧‧Input interface 123‧‧‧External power supply 124‧‧‧Power cord 126‧‧‧Motor drive circuit 128‧‧‧Control circuit 130‧‧‧Hall sensor 132‧‧‧Memory (memory means) 134‧‧‧Wiring 136‧‧‧Resistance element 200‧‧‧Electric screwdriver 202‧‧‧Electric screwdriver body 204‧‧‧Controller 206‧‧‧Communication cable 210‧‧‧Tool shell 212‧‧‧Electric motor 222‧‧‧Input interface 223‧‧‧External power supply 224‧‧‧Power cord 226‧‧‧Motor drive circuit 228a‧‧‧Control circuit 228b‧‧‧Control circuit 230‧‧‧ Hall sensor 232a‧‧‧Memory 232b‧‧‧Memory 238a‧‧‧Communications Department 238b‧‧‧Communications Department

Fig. 1 is an external view of an electric screwdriver according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram of the electric screwdriver of FIG. 1. FIG.

Fig. 3 is a diagram showing another embodiment of the rotation detection means.

FIG. 4 is a flowchart showing the operation of the electric screwdriver of FIG. 1 at the time of starting.

5 is an external view of an electric screwdriver according to a second embodiment of the present invention.

6 is a functional block diagram of the electric screwdriver of FIG. 5.

7 is a flowchart showing the operation of the electric screwdriver of FIG.

Claims (8)

A control circuit for an electric tool, the electric tool is provided with: an electric motor; a rotation detection means that detects the rotation of the electric motor and then transmits the rotation detection signal; and an information memory means that saves control with the electric motor Related setting data; it is characterized in that the control circuit determines whether the electric motor is rotating based on the rotation detection signal when a voltage is applied to the control circuit. When the electric motor is rotating, the information storage means is not stored take. A control circuit as claimed in item 1 of the patent scope, wherein the control circuit is set to allow access to the information storage means when it is determined that the rotation stop time of the electric motor is greater than a predetermined reference time. The control circuit as claimed in item 2 of the patent scope, wherein the control circuit is set to: when the stop time is more than the reference time, access the information memory means and then read the setting data, and then based on the reading Setting data, and set the control conditions of the power tool. The control circuit as claimed in item 2 of the patent scope, wherein the control circuit is set to: once access to the information memory means is allowed, regardless of whether the electric motor rotates or not, the state where access to the information memory means is allowed is maintained . For example, in the control circuit of the first patent application, the information storage means is a readable and writable memory. An electric tool comprising: an electric motor; a rotation detection means which detects the rotation of the electric motor and transmits a rotation detection signal; an information memory means which saves setting data related to the control of the electric motor; and if requested The control circuit of any one of the first to fourth patent scope. A control method of an electric tool, the electric tool is provided with: an electric motor; a rotation detection means, which detects the rotation of the electric motor and transmits the rotation detection signal; an information memory means, which saves the settings related to the control of the electric motor Data; and a control circuit; characterized in that the control method includes: the step of detecting the rotation of the electric motor by the rotation detection means when a voltage is applied to the control circuit; and when the electric motor is rotating, it is wrong The steps of accessing the information memory means. For example, the control method of item 7 of the patent application scope includes: the step of calculating the time when the rotation of the electric motor stops; when the stop time is more than the reference time, the information memory means The step of accessing and reading the setting data; the step of setting the control conditions of the electric tool based on the read setting data; and after the setting step, whether or not the electric motor rotates, is set to allow The steps of the state of access to information memory means.

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