Torque tool with fault protection function and its operating method

Abstract

A torque tool for generating a predetermined torque and a method of operating the same are disclosed. The driver is connected to a motor via a thermal fuse and receives a power signal from an electrical power source. The thermal fuse cuts off power to the driver if power is supplied to the driver for an extended period. A comparator that receives the power signal and a reference signal is connected to a solid-state switch that is operable based on a fault signal, which is generated by the comparator. The solid-state switch is connected in series with the thermal fuse between the driver and the electrical power source and quickly cuts off power to the driver without the thermal fuse cutting off the power signal if the voltage level of the power signal falls below a threshold voltage.

Description

Technical Field

[0001] The present disclosure generally relates to torque tools, and more specifically to torque tools having a fault protection function.

Background Art

[0002] Motors are generally driven using MOSFET-based motor drivers. For example, in a common configuration, one or more high-side MOSFETs and one or more low-side MOSFETs are provided. The motor is driven by a series of switching of such high-side and low-side MOSFETs. This type of motor driver has various fault modes. The MOSFET may fail when a voltage exceeding the rated maximum or minimum voltage level is applied. This can occur when the power supply voltage is too high or too low, or when a voltage spike or transient voltage occurs. Also, the MOSFET may fail when exposed to an excessive current level. This can happen when the motor is stopped or in an overload condition, or when a short circuit occurs in the motor or wiring. Since the MOSFET generates heat during on / off switching, it may fail due to overheating in case of insufficient heat dissipation or overcurrent conditions. Furthermore, MOSFET-based motor drivers may also fail due to electrostatic discharge, gate oxide breakdown, and / or electromagnetic interference.

[0003] In one failure mode, both the high-side and low-side MOSFETs may be turned on simultaneously. In this case, a short circuit occurs between the positive and negative power supplies. This can occur due to a failure in the control circuit that turns on both MOSFETs simultaneously, or due to a short circuit in the MOSFETs themselves. When this failure mode occurs, the power flowing through the MOSFETs can rapidly reach extremely high levels (e.g., large currents of 300A or more), potentially causing the MOSFETs to overheat, fail, or even rupture. Furthermore, this power can damage other components in the motor driver circuit, such as the gate driver, power supply circuit, or microcontroller. This type of failure mode is sometimes called a "shoot-through" or "cross-conduction" failure.

[0004] To prevent such failure modes, MOSFET-based motor drivers are typically designed with protective features such as dead-time insertion to ensure that both MOSFETs are not turned on simultaneously. Dead-time insertion involves a short delay between turning off one MOSFET and turning on the other, preventing both MOSFETs from turning on at the same time. However, such delays can negatively impact the performance and capabilities of torque tools.

[0005] Thermal fuses are widely used to prevent damage to electrical equipment from excessive power flow. They are a type of electrical safety device designed to protect electronic equipment and appliances from overheating and fire. They are typically disposable devices that operate like electrical fuses but are activated by heat. A thermal fuse consists of a container filled with a special material that melts or decomposes when it reaches a specific temperature. When current is applied, the fuse heats up via Joule heating. When the temperature of the thermal fuse exceeds a specified limit, it activates, interrupting the electrical circuit and cutting off power to the equipment. Thermal fuses are configured to operate within their rated operating range (specified by the operating range of current and voltage). Thermal fuses are generally unpredictable; for example, the time it takes for the fuse to blow under certain currents and voltages can vary significantly, making them difficult to predict. They also have low accuracy regarding the operating range and temperature at which power is cut off, and their response to overcurrents and / or overvoltages is relatively slow. Thermal fuses have the advantage of being simple in structure and inexpensive to manufacture and install, but they are disposable devices that need to be replaced after activation.

[0006] Torque tools are often over-engineered to meet safety requirements and standards; that is, motors and motor drivers are used that are more powerful than necessary. As a result, for safety reasons, torque tools tend to be heavier, more expensive, or larger. [Overview of the project]

[0007] According to one aspect of the present disclosure, a torque tool is provided for generating a predetermined torque. The torque tool includes a driver electrically connected to an electrical power source to receive a power signal at a predetermined voltage level and current level; a motor electrically connected to the driver to generate a predetermined torque in response to the supply of a power signal to the driver such that the voltage level is a first voltage and the current level is a first current; a thermal fuse electrically positioned between the electrical power source and the driver and configured to interrupt a power signal to the driver if the supply of a power signal to the driver is continuous for an extended period of time and the current level during the extended period is lower than a first current; an analog circuit electrically positioned between the electrical power source and the driver and connected in series with the thermal fuse, defining a solid-state switch that can be operated on fault signals, and enabling rapid interruption of the power signal to the driver; and a comparator connected to the solid-state switch and configured to generate a fault signal based on a power signal and a predetermined reference signal, and selectively operating the solid-state switch in response to a drop from a threshold voltage lower than a first voltage, so as to quickly stop the power signal without the thermal fuse stopping the power signal, thereby mitigating overcurrent.

[0008] Another aspect of the present disclosure provides a method for operating a torque tool that generates a predetermined torque. This method includes: supplying a power signal having a voltage level and a current level from an electrical power source to a driver via a thermal fuse configured to stop the power signal to the driver if the power signal to the driver is supplied for an extended period of time (during which the current level is lower than a first current); driving a motor with the driver to generate a predetermined torque in response to the power signal supply to the driver such that the voltage level is a first voltage and the current level is a first current; generating a fault signal using a comparator based on the power signal and a predetermined reference signal; and operating a solid-state switch electrically arranged in series with the thermal fuse between the driver and the power source based on the fault signal, so as to quickly stop the power signal to the driver in order to mitigate an overcurrent without the thermal fuse stopping the power signal if the voltage level falls below a threshold voltage lower than a first voltage.

[0009] A torque tool for generating a predetermined torque is provided according to yet another aspect of the present disclosure. The torque tool comprises a driver electrically connected to an electrical power source to receive a power signal at a certain voltage and current level; a motor electrically connected to the driver, configured to generate a predetermined torque in response to the supply of the power signal to the driver, wherein the voltage level is a first voltage and the current level is a first current when the power signal is supplied; and a motor electrically positioned between the power source and the driver, configured to stop the power signal to the driver when the power signal to the driver is supplied for a long time when the current level during continued supply is lower than the first current, and to stop the power signal to the driver when the power signal to the driver is supplied for 1 second or more with a current level lower than the first current. A thermal fuse configured as such; a digital circuit configured to receive a power signal and electrically connected to a driver to control a motor based on the power signal; an analog circuit configured to stop the power signal to the driver within 10 microseconds when the voltage level falls below a first threshold voltage which is lower than a first voltage, an analog low-pass filter defined by resistors and capacitors that filters the power signal and generates a filtered power signal; a first solid-state switch that is operable based on a fault signal and electrically placed in series with the thermal fuse between the driver and the power source, enabling the power signal to the driver to be stopped quickly; a circuit connected to the first solid-state switch and configured to generate a fault signal based on the filtered power signal and a predetermined reference signal, which selectively operates the first solid-state switch to quickly stop the power signal to the driver when the voltage level falls below a first threshold voltage; heat The fuse includes a comparator that mitigates overcurrent without interrupting the power signal, and an analog circuit that defines a second solid-state switch that can operate based on a digital fault signal generated by a digital circuit in response to the voltage level falling below a second threshold voltage that is lower than a first voltage and higher than a first threshold voltage, while the current level exceeds a first current.

[0010] Embodiments may include combinations of the above features.

[0011] Further details of these and other aspects relating to the subject matter of the present invention will become apparent from the following detailed description and drawings. [Brief explanation of the drawing]

[0012] Please refer to the attached diagram for further explanation. [Figure 1] This is a perspective view of an exemplary geared torque tool. [Figure 2] This is a schematic circuit diagram of the fault protection circuit for the torque tool according to this embodiment. [Figure 3] This is a schematic block diagram of the fault trigger of the fault protection circuit according to this embodiment. [Figure 4A] This figure schematically shows the temporal change in the power level of the power signal according to this embodiment. [Figure 4B] This figure schematically shows the temporal changes in the current and voltage levels of the power signal according to this embodiment. [Figure 5] This is a schematic circuit diagram of a fault protection circuit for a torque tool according to another embodiment. [Figure 6] This flowchart shows an example of how a torque tool operates to generate a predetermined torque. [Figure 7] A block diagram of the computing or processing device according to this embodiment is shown.

[0013] <Detailed description of the invention>

[0014] The following disclosure relates to a torque tool equipped with a fault protection system. In some embodiments, the apparatus and methods disclosed herein enable lighter and smaller torque tools, as well as lower cost, lower complexity, and safer operation.

[0015] Various embodiments will be described in relation to the drawings.

[0016] For example, in the operation of a normal torque tool such as tightening a bolt, the power supplied to the motor increases the torque applied until it reaches a predetermined torque, that is, a torque corresponding to a predetermined peak power (and current). This predetermined torque may be the torque associated with the torque tool or may be selectable. When the predetermined torque is reached, the torque tool quickly releases the load on the bolt to avoid over-tightening. Therefore, the torque is not continuously applied at or near the predetermined torque value. It has been found advantageous to configure the torque tool such that the predetermined torque causes a predetermined peak power (or current) to be higher than the rated operating power (or current) of the motor 122. This allows the motor to be made smaller, increasing the drive time, reducing the weight, and lowering the cost. However, it has been found that such a setting increases the risks of thermal damage, fire, sparks, ignition, and smoke.

[0017] As a particularly common failure mode in torque tools, it has been found that cross-conduction or shoot-through occurs. These risks are reduced by cutting off the power supply to the driver using a high-speed switch operated by high-speed electronics when the power level exceeds a predetermined peak power.

[0018] FIG. 1 is a perspective view of an exemplary geared torque tool 100.

[0019] The torque tool 100 includes an electric motor 102 that defines a rotor and a stator. The motor 102 is securely housed within the outer housing or handle assembly of the torque tool 100. In some embodiments, it is understood that the outer housing 102 may not include a handle. For example, the torque tool 100 may be remotely operated by a pendant.

[0020] For example, the motor 102 may be a brushless direct current (DC) motor powered by one or more batteries. In some embodiments, other types of motors may be suitable for specific applications.

[0021] The motor 102 is connected to the gear train of the gearbox 104 to form a drive assembly that terminates at the output shaft 106. The drive assembly enables torque transmission and supports the gearbox 104 during torque transmission. The motor 102 and the gearbox 104 are generally arranged in series and axially adjacent to each other (with respect to the longitudinal axis 108 that defines the axis of rotation of the rotor), and / or may be arranged without overlapping each other (or at least partially fitting into each other).

[0022] The output shaft 106 extends axially outward from the gearbox 104 distal to the motor 102. The output shaft 106 is driven by the motor via the gearbox 104 and acts to rotate about the longitudinal axis 108. The output shaft 106 defines a tool head or is suitable for connection to a tool head, and defines a fitting adapter or spindle for fitting with a workpiece, such as a threaded fastener, etc., enabling rotation by the torque tool 100.

[0023] In various embodiments, the user trigger 112 is attached on or near the handle 110 of the torque tool 100 to enable an operator to operate the torque tool 100. In various embodiments, the outer housing assembly may further include a trigger guard 114 to prevent accidental operation of the user trigger 112.

[0024] In some embodiments, for example, the electronic circuitry 117, including a controller and / or other digital and / or analog circuits, may be housed at least partially inside or between two opposing portions of the exterior housing assembly, for example, securely sandwiched between them or positioned in a pocket formed between them. In various embodiments, the electronic circuitry 117 may be housed at the distal end of the handle 110 from the motor 102. Advantageously, in some embodiments, a portion of the electronic circuitry 117 (e.g., its housing) may form the lower end of the exterior housing assembly. It is also understood that additional or alternative electronic circuits may be provided at other locations within the torque tool 100, for example, on a printed circuit board (PCB) mounted adjacent to the motor 102 of the torque tool 100.

[0025] The battery 118 can be mounted on the torque tool 100. The battery 118 powers the torque tool 100, enhances portability, and enables wireless operation of the torque tool. In some embodiments, the battery 118 may be directly engaged with and entirely adjacent to the electronic circuit 117. For example, the electronic circuit 117 may be configured for fault protection. The battery 118 is understood to mean one or more batteries, each comprising one or more cells. The one or more batteries comprising the battery 118 may be connected to the motor 102 to supply power to the motor 102. For example, a dual battery can include two batteries that work in coordination to supply power to the motor 102. It is also understood that in some embodiments, a power source other than the battery 118 may be used. For example, the torque tool 100 may include wiring that allows for an electrical connection to an electrical socket to supply AC power.

[0026] In some embodiments, the exterior housing assembly is formed at least partially from plastic, and for example, each part of the exterior housing assembly may be a plastic part formed by injection molding.

[0027] The drive assembly of the torque tool 100 may be applied so as to be rigidly coupled to one end of the external reaction arm 107 by frictional or fastening engagement between a ring on the gearbox 104 and a slot on the reaction arm 107 that engages with the ring. For example, the reaction arm 107 may be a metal bar or other rigid member. The other end of the reaction arm 107 may be rigidly coupled to or attached to a non-movable structure to allow rotation of the output shaft 106. In some embodiments, the reaction arm 107 may not be provided.

[0028] Figure 2 shows a schematic circuit diagram of the fault protection circuit 120 of the torque tool 100 according to this embodiment.

[0029] The torque tool 100 is configured to generate a predetermined torque. For example, such torque may be selectable by the user operating the torque tool 100. The predetermined torque is associated with a peak current, which may be associated with the peak power received by the driver 124. The driver 124 is electrically connected to the motor 122 of the torque tool 100 to generate the predetermined torque. The driver 124 is electrically connected to receive a power signal 125 from the battery 118 in terms of current and voltage levels. These current and voltage levels define the power level. The current and voltage levels may vary depending on the switching of the driver 124. In normal operation, the driver 124 increases the current level until it reaches the peak current, and then rapidly decreases the current level. As the current level increases, the voltage level may decrease, while the power level increases.

[0030] The operation of the driver 124 may be controlled by a controller or other circuit. In some embodiments, the driver 124 may be controlled in a feedforward or feedback manner. In some embodiments, the driver 124 may increase the current up to a predetermined current to achieve a predetermined torque, for example, such a predetermined current may be specified or determined based on the model of the electric motor and its connected components. In some embodiments, the driver 124 may increase the current level to achieve a predetermined torque based on measured current, torque, rotational speed, strain rate, and / or other observable values ​​indicating torque.

[0031] Circuit 120 further includes an analog circuit 128 and one or more thermal fuses 126A, 126B, the thermal fuses being electrically positioned between the battery 118 and the driver 124. Analog circuit 128 specifies a solid-state switch 130A electrically positioned between the driver and the battery 118, which is connected in series with the thermal fuses 126A, 126B. This allows the operation of switch 130A to quickly interrupt the power signal 125 to the driver 124. For example, switch 130A may be a MOSFET (metal-oxide-semiconductor field-effect transistor) and may be configured to quickly interrupt and / or supply the power signal 125 to the driver 124 based on the gate input voltage to the MOSFET. The thermal fuses 126A, 126B may be selected individually or in combination to comply with safety standards applicable to torque tools, for example, IEC standard 62841-1-2014, the contents of which are incorporated herein by reference.

[0032] In this specification, “solid-state switch” may refer to a transistor-based switch that enables appropriate power transfer, can operate with relatively small current signals, and can rapidly connect or disconnect the source gate and drain gate. Transistor-based switches include MOSFETs, insulated-gate bipolar transistors (IGBTs), and bipolar junction transistors (BJTs). The solid-state switch 130A may be a high-power switch such as a MOSFET or IGBT.

[0033] The analog circuit 128 also defines a fault trigger 132 operably connected to the solid-state switch 130B, for example, to supply a gate voltage input to a MOSFET. In various embodiments, the fault trigger 132 may be an analog trigger configured with virtually no digital circuitry to avoid analog-to-digital conversion, which could result in unacceptable delays for the fault protection system. The fault trigger 132 may be configured to operate the solid-state switch 130B based on a power signal 125 to prevent overcurrent to the driver 124. In various embodiments, the operation of the solid-state switch 130B may operate the solid-state switch 130A. In some embodiments, the fault trigger 132 may be directly connected to the solid-state switch 130A without an intermediate connection via the solid-state switch 130B.

[0034] The fault trigger 132 generates a fault signal 148. The solid-state switch 130B can operate based on this fault signal 148, allowing it to quickly cut off the power signal 125 to the driver 124. In some embodiments, the fault signal 148 may be a binary signal, such as a high voltage or a low voltage. For example, a low voltage may indicate no fault detection, and a high voltage may indicate fault detection.

[0035] In the embodiment shown in Figure 2, solid-state switch 130A is controlled by solid-state switches 130B and 130C connected in series. Solid-state switch 130C may be operated by a main control unit or MCU 134 (or a controller constituting part thereof) electrically connected to it. For example, in some embodiments, if any of solid-state switches 130A, 130B, or 130C is opened, the power supply to the driver 124 may be cut off.

[0036] The MCU 134 may be connected to a fault trigger 132. In some embodiments, the MCU 134 may be connected to a driver 124 and define a controller that controls the power or current supplied to the motor 122 by the driver 124. This controller may be configured to receive a power signal 125 and be electrically connected to the driver 124 to control the motor 122 based on the power signal 125 to generate a predetermined torque.

[0037] In some embodiments, the MCU 134 may be configured to determine the current associated with the driver 124 using an electrical connection 138. In some embodiments, the current supplied to the driver 124 may be monitored using a current monitoring line 138. In various embodiments, the MCU 134 may be configured to control the motor 122 via the driver 124 based on the detected torque generated by the motor 122. In various embodiments, the MCU 134 may include digital circuits such as one or more digital microprocessors.

[0038] In various embodiments, a user trigger 112 may be connected to an MCU 134. The user trigger 112 is capable of generating a user input signal 137. The MCU 134 may be configured to receive the user input signal 137. Under normal operation, the MCU 134 may be configured to control the motor 122 based on the user input signal 137 and generate a predetermined torque using a power signal, provided that a fault signal 149 indicates no fault condition. If the fault signal indicates a fault, the MCU 134 may avoid or stop supplying power to the driver 124. Alternatively, the MCU 134 may generate an output signal to supply to an output device 139, such as a display device, speaker, or LED light. In some embodiments, the display device may generate a user message based on the output signal. For example, the user message may be descriptive. Examples of user messages may include warnings to the user, including instructions, hints, or advice regarding the safe operation of the torque tool 100, and instructions regarding the replacement and / or removal of the battery 118.

[0039] Figure 3 shows a schematic block diagram of the fault trigger 132 according to this embodiment.

[0040] The fault trigger 132 includes a comparator 140 connected to the solid-state switch 130B. The comparator 140 is configured to receive a predetermined reference signal 142 and a power signal 125 and may be driven by a supply voltage 146 (or supply rail voltage). In some embodiments, the reference signal 142 is generated by a voltage regulator 144. In some embodiments, the reference signal 142 may be, for example, a 5V reference signal. The comparator 140 generates a fault signal 148 as an output by comparing the reference signal 142 and the power signal 125. The comparator 140 is configured to generate the fault signal 148 based on the power signal and the predetermined reference signal and to selectively operate the solid-state switch 130B.

[0041] In some embodiments, the power signal 125 is filtered through a low-pass filter 150A before being supplied to the comparator 140 as a filtered power signal. The cutoff frequency of the low-pass filter 150A may be 100–500 kHz, or approximately 160 kHz. Advantageously, such a cutoff frequency allows for sufficiently fast operation of the solid-state switch 130B to suppress excessive switching due to high-frequency noise, while mitigating risks such as fire and thermal damage. Excessive switching can lead to component failure or undesirable motor operation.

[0042] In some embodiments, the output of the comparator 140 is filtered through another low-pass filter 150B before being supplied to the MCU 134. In contrast, the solid-state switch 130B may receive the unfiltered output of the comparator 140. Advantageously, this allows for high-speed operation of the solid-state switch 130B, reducing risks such as fire and thermal damage.

[0043] In some embodiments, the cutoff frequency of the low-pass filter 150B may be 200-300 Hz, or approximately 265 Hz.

[0044] The filtered fault signal 149 may be supplied to the MCU 134. The MCU 134 may be configured to control the motor 122 based on the user input signal 137 when the filtered fault signal 149 shows a voltage level higher than a threshold voltage, and to generate a predetermined torque using the power signal.

[0045] Low-pass filters 150A and 150B are analog filters, such as low-pass filters, implemented using one or more resistors and one or more capacitors, thereby enabling faster processing. For example, they may not require a digital-to-analog converter. In some embodiments, inductors may also be used.

[0046] As can be understood, in some embodiments, other components may be provided within the fault trigger 132.

[0047] As shown in Figure 3, a resistor and a diode may be provided to supply an output that provides grounding in the event of a short-circuit fault.

[0048] Figure 4A is a schematic diagram showing the temporal change in the power level of a power signal 125 according to one embodiment.

[0049] The power of power signal 125 increases until it reaches peak power. Peak power is achieved when a predetermined torque is reached. Therefore, to avoid continuous application of torque, the power then drops sharply. Peak power is reached over time t torque This can sometimes be achieved.

[0050] During the starting operation of motor 122 and / or driver 124, the starting behavior may result in a stationary point as shown in Figure 4A, which is usually much lower than the peak power. After starting is complete, the power increases monotonically, and t torque It can rise until it reaches the peak power level.

[0051] Figure 4B is a schematic diagram showing the temporal changes in the current level and voltage level of a power signal 125 according to one embodiment.

[0052] The current supplied to motor 122 is the first current I first The voltage increases until it reaches V. The first current may be the peak current, or, during normal operation of the torque tool 100, it may be the maximum current that the driver 124 receives, at least until the next tightening cycle begins. At the same time, the voltage level increases from the initial voltage to the first voltage V. first It decreased to V first This may be the trough voltage, or it may be the minimum voltage during normal operation of the torque tool 100. The initial voltage can be determined by the battery characteristics.

[0053] The first voltage may be associated with a first current, so that the motor 122 generates a predetermined torque when the power signal 125 supplied to the driver 124 has a voltage level of the first voltage and a current level of the first current.

[0054] The thermal fuses 126A and 126B are configured to operate within an operational envelope defined by a current range. In some cases, a voltage range may also be specified. When operating within the operational envelope, the thermal fuses 126A and 126B can operate as intended; that is, heating (such as Joule heating) causes the temperature of the fuses 126A and 126B to rise relatively slowly, eventually causing one or more fuses 126A and 126B to operate and interrupt the circuit. Operating the thermal fuses 126A and 126B outside their operational envelope may result in unpredictable behavior. This operational envelope includes a first current and a first voltage. Therefore, at least one thermal fuse 126A or 126B may be configured to interrupt the power signal 125 to the driver 124 if the power signal 125 to the driver 124 has been supplied with a first current and a first voltage for an extended period. Furthermore, in various embodiments, the operational envelope includes a second current I lower than the first current. second It may extend to this extent. In the torque tool 100, this second current is a second voltage V that is higher than the first voltage. second This can be associated with the following. Therefore, at least one thermal fuse 126A, 126B may be configured to interrupt the power signal 125 to the driver 124 if the power signal 125 is supplied to the driver 124 for an extended period of time. In this case, the current level during the continuous supply may be between a first current and a second current. The voltage level during the continuous supply may be between a first voltage and a second voltage.

[0055] It is understood that the operating range may include currents higher than the first current. However, to ensure that the thermal fuse activates in a timely manner to protect driver 124, the operating range of the thermal fuse may be set to be relatively narrow. Thermal fuses with high precision and predictable performance can be difficult and expensive to manufacture. Therefore, it has been found to be advantageous to use thermal fuses with a safety factor.

[0056] The motor 122 may be designed to enable substantially long-duration or continuous operation at a rated operating power, or current or voltage, which may be defined in terms of current and voltage. This rated operating power, or current and voltage, defines the maximum load of the motor and is defined taking into account the service factor, which may be determined based on various factors such as the motor's power loss characteristics, the mechanical fatigue of the motor components, the thermal performance of the motor component materials, and the heat dissipation performance. In some embodiments, a second current and / or a second voltage define the rated (or maximum) operating current and / or operating voltage of the motor 122, respectively.

[0057] In the normal operation of the torque tool 100, for example when tightening a bolt, the applied torque increases until a predetermined torque is reached, as shown in Figures 4A and 4B. Once this predetermined torque is reached, the torque tool 100 quickly releases the bolt to prevent overtightening. Therefore, the torque is not sustained for a long period of time at the predetermined torque. It has been found that it is advantageous to set the torque tool 100 so that its peak current (or power) is higher than the rated operating current (or power) of the motor 122. It has also been found that it is advantageous to design other electronic components, such as printed circuit board components, wiring patterns, and conductors, to operate at lower currents. This allows for miniaturization, expansion of the operating range, weight reduction, and cost reduction of the motor and electronic circuits. However, this may significantly increase the risk of fire and / or thermal damage.

[0058] While the motor 122 can be driven above its rated power for short periods, prolonged operation exceeding the rated current and / or rated power may lead to decreased efficiency and a shortened motor lifespan. Furthermore, it increases the risk of motor or driver failure. Therefore, at least one thermal fuse 126A, 126B may be configured to reliably interrupt the power signal 125 to the driver 124 if a power signal 125 exceeding the rated power is supplied to the driver 124 for an extended period.

[0059] Even so, thermal fuses 126A and 126B alone may not adequately mitigate all significant risks. A short circuit in driver 124 can cause a rapid increase in current within the circuit. In overcurrent conditions, electronic components, particularly the wiring on printed circuit boards, can overheat, increasing their resistance and potentially reducing the current in the circuit. This is particularly noticeable if the electronic components are poorly designed. In relatively short-duration overcurrent conditions, thermal fuses 126A and 126B may not activate, and may remain non-activated due to the low current after the electronic components have sustained resistance damage. Nevertheless, the electronic components continue to overheat, potentially leading to a prolonged period of increased risk of fire and further thermal damage.

[0060] Operating a motor beyond its rated capacity reduces the circuit's margin against overcurrents, such as those caused by short circuits. This increases the risk of fire and / or thermal damage, making those risks more imminent. For example, in some embodiments, fire and smoke may occur when the current increases to a level where the associated voltage level is 5V. Thermal fuses act by Joule heating and therefore require time to activate. Consequently, thermal fuses may not be effective in mitigating the risks associated with short-circuit conditions.

[0061] The increased risk is mitigated by using a high-speed switch operated by high-speed electronic equipment, which cuts off the power supply to the driver 124 when the voltage level reaches a first threshold voltage 160A that is lower than the first voltage and may indicate a current associated with a fault condition such as a short circuit.

[0062] In particular, the comparator 140 is configured to generate a fault signal 148 based on the power signal 125 and a predetermined reference signal 142, selectively operating the solid-state switch 130B to quickly stop the power signal 125 to the driver 124 when the voltage level falls below a first threshold voltage 160A. heat Fuses 126A and 126B mitigate overcurrents without interrupting power signal 125.

[0063] The first threshold voltage 160A may be determined based on the characteristic duration for generating a fault signal 148 in response to a power signal 125, and the typical or worst-case current / voltage / power curve behavior at the time of fault occurrence (e.g., the time interval from fault occurrence to reaching current / voltage / power associated with smoke or fire).

[0064] It is important to use solid-state switches and analog electronics for high-speed switching because of the use of digital electronics that require digital-to-analog conversion (or vice versa). heat The reduced response speed due to fuses and the like may be insufficient to avoid smoke and fire. In some embodiments, at least one thermal fuse 126A, 126B may be configured to stop the power signal 125 to the driver 124 in response to the power signal 125 being supplied to the driver 124 for at least 1 second while the current level is lower than (or approximately equal to) the first current and higher than the second current. On the other hand, the analog circuit 128 is configured to stop the power signal 125 to the driver 124 within about 10 microseconds after the voltage level falls below the first threshold voltage 160A.

[0065] In various embodiments, the digital circuitry of the MCU 134 may be configured to receive a power signal 125. The solid-state switch 130C may be operable based on a digital fault signal generated by the digital circuitry in response to the voltage level falling below a second threshold voltage 160B while the current level exceeds a first current. The second threshold voltage 160B may be set lower than the first voltage and higher than the first threshold voltage 160A. The second threshold voltage 160B is determined based on the characteristic duration of the analog-to-digital conversion (e.g., 0.5 seconds), the digital processing, and the typical or worst-case power curve behavior at the time of fault, ensuring that a digital fault signal is transmitted in a timely manner to avoid motor failure and / or the generation of fire or smoke. If the digital circuitry fails to stop the power signal 125 to the driver 124, a fault trigger 132 generates a fault signal 148 to stop the power signal 125. This configuration has the advantage of providing multiple layers of fault protection.

[0066] For example, the first threshold voltage 160A may be approximately 5V, the second threshold voltage 160B may be approximately 12V, and the first voltage may be approximately 14V.

[0067] As used herein, "long operating period" may be at least equivalent to the characteristic response time of a thermal fuse.

[0068] Figure 5 is a schematic diagram of a fault protection circuit 120 for a torque tool 100 in another embodiment of the present invention.

[0069] In Figure 5, the MCU 134 is operably connected to the solid-state switch 130D, which may be connected to the solid-state switch 130E. A fault trigger 132 may be operably connected to supply a signal 151 to the solid-state switch 130E. A user input signal 137 may be generated by the operation of the user trigger 112 and supplied to the MCU 134. In response, the MCU 134 may operate the solid-state switch 130D to close the switch 130E. In this state, the battery 118 may be allowed to continue supplying power to the fault trigger 132 even while a fault condition exists.

[0070] If the driver 124 is damaged, when the torque tool 100 is restarted, the voltage level to the driver 124 remains low, causing the fault trigger 132 to generate a fault signal 148 and cut off the power supply to the driver 124. In this case, the solid-state switch 130E receives the signal 151 and cuts off the power supply to the driver 124 while allowing power to be supplied to the MCU 134 and the fault trigger 132. This configuration has the advantage of allowing the torque tool 100's circuitry to operate in isolation, protecting both the user and the torque tool 100.

[0071] In some embodiments, the digital circuitry of the MCU 134 may be configured to generate an output signal 162 based on processing a fault signal when the fault signal indicates the presence of a fault condition and the user input signal indicates a user request to start the device. An output device 139 may receive this output signal and generate a warning to the user based on the output signal. For example, the display device may indicate to the user that the torque tool and / or its circuitry is damaged, suggest replacing the part, suggest removing the battery to protect it, and / or suggest sending the tool to the manufacturer for repair.

[0072] In Figure 5, the MCU 134 may also be operably connected to the solid-state switch 130F to cut off the power supply to the resistor in order to protect the resistor.

[0073] Figure 6 is a flowchart showing an example of a method 600 for operating a torque tool to generate a predetermined torque.

[0074] Step 602 of Method 600 includes supplying a power signal having a voltage level and a current level from an electrical power source to a driver. This power signal is supplied to the driver via a fuse configured to stop the power signal to the driver if the power signal to the thermal driver is supplied for an extended period of time. The voltage level supplied for an extended period of time is higher than a first voltage, and the current level supplied for an extended period of time is lower than a first current.

[0075] Step 604 of Method 600 includes driving a motor with a driver such that the voltage level is a first voltage and the current level is a first current, thereby generating a predetermined torque in response to the supply of a power signal to the driver.

[0076] Step 606 of Method 600 includes the step of generating a fault signal based on a power signal and a predetermined reference signal using a comparator.

[0077] Step 608 of Method 600 includes the step of operating a solid-state switch electrically arranged in series with a thermal fuse between the driver and the power supply, which, based on a fault signal, in response to the voltage level falling below a threshold voltage lower than a first voltage, allows the thermal fuse to quickly shut off the power signal to the driver in order to mitigate an overcurrent without shutting off the power signal.

[0078] In some embodiments of Method 600, the solid-state switch is a metal-oxide-semiconductor field-effect transistor.

[0079] In some embodiments of Method 600, the threshold voltage is a first threshold voltage, and the solid-state switch is a first solid-state switch. Method 600 may further include the step of operating a second solid-state switch based on a digital fault signal generated by a digital circuit configured to receive a power signal when the voltage level is lower than the first voltage and below a second threshold voltage which is higher than the first threshold voltage, and the current level is above the first current.

[0080] Some embodiments of Method 600 may further include the step of supplying a power signal to a controller electrically connected to the driver, controlling the motor based on the power signal, and generating a predetermined torque.

[0081] In some embodiments of Method 600, a solid-state switch and a comparator constitute an analog circuit, and a thermal fuse is configured to cut off the power signal to the driver if the driver has been supplied with a power signal for at least one second while the current level is lower than (or approximately the same as) a first current. The analog circuit is also configured to cut off the power signal to the driver within 10 microseconds after the voltage level falls below a threshold voltage.

[0082] Some embodiments of Method 600 further include the step of filtering a power signal using an analog low-pass filter to generate a filtered power signal, wherein a comparator is configured to receive the filtered power signal and generate a fault signal.

[0083] In some embodiments of Method 600, the cutoff frequencies of the analog low-pass filter are above 100 kHz and 500 kHz.

[0084] Some embodiments of Method 600 may further include the steps of receiving a user input signal, processing a fault signal and the user input signal in response to the user input signal and generating an output signal based on the fault signal, and generating a user warning on a display device based on the output signal.

[0085] Figure 7 shows a block diagram of a computing device or processing device 700 according to one embodiment.

[0086] As an example, the output device 139, the electronic circuit 117, the MCU 134, its controller and / or a part of its digital circuit, or a combination thereof, can be implemented using the processing device 700 example shown in Figure 7.

[0087] The processing device 700 includes at least one processor 702, memory 704, at least one input / output (I / O) interface 706, and / or at least one network communication interface 708.

[0088] The processor 702 may be a microprocessor or microcontroller, a digital signal processing (DSP) processor, an integrated circuit, a field-programmable gate array (FPGA), a reconfigurable processor, a programmable read-only memory (PROM), or a combination thereof.

[0089] The memory 704 may include, for example, machine-readable or computer-readable memory located internally or externally, such as: random access memory (RAM), read-only memory (ROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and / or ferroelectric RAM (FRAM).

[0090] The I / O interface 706 may enable the processing device 700 to interconnect with one or more input devices located on the torque tool, such as a trigger, interface button and / or touchscreen, a keyboard, mouse, camera and / or microphone, a display screen and / or speaker.

[0091] The network interface 708 may be configured to receive and transmit data.

[0092] The embodiments described herein provide non-limiting examples of possible embodiments of the Art. By examining this disclosure, those skilled in the art will recognize that modifications can be made to the embodiments described herein without departing from the scope of the Art. For example, the solid switches disclosed herein may be implemented using insulated-gate bipolar transistors (IGBTs), single heat Only two or more fuses may be provided. heat Fuses may be provided in series, and the power source may be an AC power source. Furthermore, those skilled in the art may make further modifications based on this disclosure, but such modifications will remain within the scope of the present art.

Claims

1. A torque tool for generating a predetermined torque, A driver electrically connected to receive power signals of voltage level and current level from a power source, A motor electrically connected to a driver to generate a predetermined torque when a power signal is supplied to the driver, wherein the voltage level becomes a first voltage and the current level becomes a first current when a power signal is supplied, A thermal fuse electrically placed between an electrical power supply and a driver, The system is configured to stop the power signal to the driver if the power signal to the driver continues to be supplied, and the current level during continuous supply is lower than the first current, and a thermal fuse is used. It is an analog circuit, A solid-state switch that can operate based on a fault signal, electrically arranged in series with a thermal fuse between the driver and the power supply, enabling rapid termination of the power signal to the driver, and Analog circuit defining a comparator connected to a solid-state switch, which generates a fault signal based on a power signal and a predetermined reference signal, and is configured to selectively operate the solid-state switch when the voltage level falls below a threshold voltage lower than a first voltage, thereby quickly stopping the power signal to the driver and mitigating overcurrent without the thermal fuse stopping the power signal. A torque tool having the following features.

2. The torque tool according to claim 1, wherein the solid-state switch is a metal-oxide-semiconductor field-effect transistor.

3. The threshold voltage is a first threshold voltage, the solid-state switch is a first solid-state switch, and further, A digital circuit configured to receive the aforementioned power signal, and The torque tool according to claim 1, further comprising a second solid-state switch that operates based on a digital fault signal generated by the digital circuit when the voltage level is lower than a second threshold voltage lower than a first voltage, higher than a first threshold voltage, and the current level is greater than a first current.

4. The torque tool according to claim 1, comprising a controller configured to receive a power signal and electrically connected to a driver for controlling a motor based on the power signal and generating a predetermined torque.

5. The torque tool according to claim 1, wherein the thermal fuse is configured to stop the power signal to the driver if the power signal has been supplied to the driver for at least one second while the current level is lower than a first current, and the analog circuit is configured to stop the power signal to the driver within 10 microseconds after the voltage level falls below a threshold voltage.

6. A torque tool according to claim 1, comprising an analog low-pass filter defined by resistors and capacitors, which filters a power signal and generates a filtered power signal, wherein a comparator is configured to receive the filtered power signal and generate a fault signal.

7. The torque tool according to claim 6, wherein the cutoff frequency of the analog low-pass filter is in the range of 100 kHz to 500 kHz.

8. A user trigger that can be operated to generate a user input signal, A digital circuit configured to process fault signals and user input signals and generate an output signal based on the fault signal in response to the user input signal, The torque tool according to claim 1, further comprising a display device configured to receive an output signal in such a way as to generate a user warning based on the output signal.

9. The torque tool according to claim 8, wherein the digital circuit includes a controller electrically connected to the driver and configured to receive the power signal and the user input signal, and the digital circuit is configured to control the motor based on the user input signal when a fault signal indicates that the voltage level is higher than a threshold voltage, and to generate a predetermined torque using the power signal.

10. A method for operating a torque tool to generate a predetermined torque, A process of supplying power signals of voltage level and current level from an electrical power source to a driver via a thermal fuse, wherein the thermal fuse is configured to stop the power signals when they are supplied to the driver for an extended period of time, and the voltage level during such extended supply is higher than a first voltage and the current level is lower than a first current; The process involves driving a motor with the driver and generating a predetermined torque in response to the supply of a power signal to the driver such that the voltage level is a first voltage and the current level is a first current, A step of generating a fault signal based on the power signal and a predetermined reference signal using a comparator, A method for operating a torque tool to generate a predetermined torque, comprising the steps of: operating a solid-state switch electrically arranged in series with the thermal fuse between the driver and the power supply, and, based on the fault signal, quickly stopping the power signal to the driver in order to mitigate an overcurrent without the thermal fuse stopping the power signal when the voltage level falls below a threshold voltage lower than a first voltage.

11. The method according to claim 10, wherein the solid-state switch is a metal oxide semiconductor field-effect transistor.

12. The threshold voltage is a first threshold voltage, the solid-state switch is a first solid-state switch, and further, The method according to claim 10, further comprising the step of operating a second solid-state switch based on a digital fault signal generated by a digital circuit configured to receive a power signal when the voltage level is lower than a first voltage and lower than a second threshold voltage which is higher than a first threshold voltage, and the current level is higher than a first current.

13. The method according to claim 10, further comprising supplying the power signal to a controller electrically connected to the driver, controlling the motor based on the power signal, and generating a predetermined torque.

14. The method according to claim 10, wherein the solid-state switch and the comparator define an analog circuit, the thermal fuse is configured to stop the power signal to the driver if the power signal has been supplied to the driver for at least one second while the current level is lower than a first current, and the analog circuit is configured to stop the power signal to the driver within 10 microseconds after the voltage level falls below a threshold voltage.

15. The method according to claim 10, further comprising the configuration that the power signal is filtered using an analog low-pass filter to generate a filtered power signal, and the comparator receives the filtered power signal to generate a fault signal.

16. The method according to claim 15, wherein the cutoff frequency of the analog low-pass filter is greater than 100 kHz and greater than 500 kHz.

17. Receives user input signals, It processes fault signals and user input signals, and generates an output signal based on the fault signal in response to the user input signal. The method according to claim 10, further comprising generating a user warning on a display device based on an output signal.

18. A torque tool for generating a predetermined torque, A driver electrically connected to an electrical power source to receive power signals in terms of voltage and current levels, A motor electrically connected to the driver and generating a predetermined torque in response to the supply of a power signal to the driver such that the voltage level is a first voltage and the current level is a first current, A thermal fuse electrically arranged between the power supply and the driver, configured to stop the power signal when a power signal is supplied to the driver for an extended period of time, wherein the current level during the extended period of supply is lower than the first current, and the thermal fuse is configured to stop the power signal when the power signal is supplied to the driver for at least one second while the current level is lower than the first current, A digital circuit that receives the power signal, is electrically connected to the driver, and is configured to control the motor based on the power signal, An analog circuit configured to stop the power signal to the driver within 10 microseconds when the voltage level falls below a first threshold voltage which is lower than a first voltage, An analog low-pass filter defined by resistors and capacitors, which filters the power signal and generates a filtered power signal. A first solid-state switch that operates based on a fault signal and is electrically arranged in series with the thermal fuse between the power supply and the driver, enabling the rapid cessation of the power signal to the driver. A comparator coupled to the first solid-state switch, which generates the fault signal based on the filtered power signal and a predetermined reference signal, and which, when the voltage level falls below the first threshold voltage, selectively operates the first solid-state switch to quickly stop the power signal to the driver in order to mitigate overcurrent without the thermal fuse stopping the power signal, and A torque tool including an analog circuit that defines a second solid-state switch that operates based on a digital fault signal generated by the digital circuit when the voltage level is lower than a first voltage and lower than a second threshold voltage which is higher than a first threshold voltage, and the current level is higher than the first current.

19. The torque tool according to claim 18, wherein the first and second solid-state switches are metal oxide semiconductor field-effect transistors.

20. The torque tool according to claim 18, wherein the cutoff frequency of the analog low-pass filter is 100 kHz or more and 500 kHz or less.

Images