Overcurrent protection for electric motors

Abstract

Overcurrent protection for the electric and motorized components of power tools, such as a tool housing, output assembly, trigger, electrical safety device, motor, indicator, controller, and power supply. The electrical safety device (e.g., a fuse) is connected in series with the power supply from the power source to the controller. When the trigger is actuated, the controller measures the current through the electrical safety device at time intervals. The controller determines the accumulated heat energy through the electrical safety device and compares this accumulated heat energy to a threshold. If the accumulated heat energy exceeds the threshold, the controller stops or interrupts power supply to the motor, thereby shutting down the motor. The controller may also activate an indicator to indicate a fault to the user.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 164,860, filed March 23, 2021, and U.S. Patent Application No. 17 / 694,242, filed March 14, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to electric motors, and more particularly to overcurrent protection for electrical components used in the operation of electric motors. Background Technology

[0004] Electric hand tools (such as, for example, electric ratchet wrenches, impact wrenches, and other actuators) are commonly used in automotive, industrial, and household applications to install and remove threaded fasteners and to apply torque and / or angular displacement to workpieces (such as, for example, threaded fasteners). Electric hand tools typically include an output component (such as a drive flange or drive chuck), a trigger switch that can be actuated by the user, an electric motor housed in a housing, and other components (such as, for example, switches, light-emitting diodes (LEDs), controllers, and power sources (such as batteries)).

[0005] Some power hand tools use a fuse connected in series with the power supply from the power source to the controller. The purpose of this fuse is to trip in the event of a fault (such as a short circuit) to protect electrical components (such as the controller, motor, and / or trigger switches) from damage due to overcurrent. However, it can be difficult to find fuses of the right size (especially for high-current tools) so that they trip quickly in the event of a fault (such as a short circuit) while still allowing the tool to operate continuously during normal operation. This results in fuses that are either too small or too large (i.e., the fuse's I...). 2 (The t rating is too low or too high). 2 The t rating is provided in the datasheet for each fuse series. A fuse that is too small will cause unnecessary interruption of operation for the protection of electrical components, while a fuse that is too large will cause high current to flow through electrical components for an extended period in the event of a fault, resulting in greater damage. Summary of the Invention

[0006] This invention relates primarily to overcurrent protection for electric motor devices (such as power tools). The tool includes a tool housing, an output assembly (such as a ratchet head assembly) adapted to provide torque to a workpiece, a trigger switch, a motor housed within the housing, an indicator, a controller, and a power supply. An electrical safety device (such as, for example, a fuse) is connected in series with the power supply from the power source to the controller. When the trigger is actuated, the controller measures the current through the fuse at time intervals. The controller calculates the current by repeatedly applying the formula current × current × time (I0 × I0) at each time interval. 2 The controller determines the accumulated heat energy using a multiplier (×t). The controller compares the accumulated heat energy to a threshold. If the accumulated heat energy exceeds the threshold, the controller stops or interrupts power supply to the motor, thus shutting it down. The controller can also activate an indicator to notify the user of a fault.

[0007] This invention utilizes a controller to limit thermal energy through electrical safety devices (such as fuses), rather than relying solely on appropriately sized electrical safety devices to protect the tool's electrical components in the event of a tool malfunction (such as a short circuit). This invention prevents electrical safety devices from prematurely and / or unnecessarily blocking or interrupting current from the power source, while also allowing the electrical safety devices to act quickly in the event of a malfunction. Furthermore, this invention enables the successful use of conventional electrical safety devices of slightly smaller size without the need to upgrade to those with higher ratings (e.g., higher IL). 2 Larger electrical safety devices (t rated value). Attached Figure Description

[0008] To facilitate understanding of the claimed subject matter, embodiments thereof are shown in the accompanying drawings. By consulting these embodiments and considering them in conjunction with the following description, the claimed subject matter, its construction and operation, and its many advantages should be readily understood and appreciated.

[0009] Figure 1 This is a perspective view of an example tool incorporating one embodiment of the present invention.

[0010] Figure 2 and Figure 3 This is a component block diagram of an electronic component of an exemplary tool incorporating embodiments of the present invention.

[0011] Figure 4 This is a block diagram illustrating the operation method of an exemplary tool incorporating one embodiment of the present invention. Detailed Implementation

[0012] While the invention allows for many different embodiments, a preferred embodiment is shown in the accompanying drawings, which will be described in detail herein. It should be understood that this disclosure is to be considered as an example of the principles of the invention and is not intended to limit the broad aspects of the invention to the illustrated embodiments. As used herein, the term "invention" is not intended to limit the scope of the claimed invention, but is a term used solely for illustrative purposes to discuss exemplary embodiments of the invention.

[0013] This invention relates primarily to overcurrent protection for electric devices such as power tools. The tool includes a tool housing, an output assembly (such as a ratchet head assembly) adapted to provide torque to a workpiece, a trigger switch, an electrical safety device, a motor housed within the housing, an indicator, a controller, and a power source (such as a battery). The electrical safety device (such as a fuse) is connected in series with the power supply from the power source to the controller. When the trigger is actuated, the controller measures the current through the electrical safety device at time intervals. The controller calculates the current by repeatedly applying the formula current × current × time (I0 × I0) at each time interval. 2 The controller determines the accumulated heat energy passing through the electrical safety device using a multi-t method. The controller compares the accumulated heat energy to a threshold. If the accumulated heat energy exceeds the threshold, the controller stops or interrupts power supply to the motor, thereby shutting it down. The controller can also activate an indicator to notify the user of a fault.

[0014] By utilizing a controller to limit thermal energy passing through conventional electrical safety devices (such as fuses), the precise sizing of these devices does not depend solely on protecting the electrical components of the tool in the event of a tool failure (such as a short circuit), as is the case with existing solutions. This invention allows the electrical safety device to act quickly in the event of a tool failure without prematurely and / or unnecessarily blocking or interrupting current from the power source. Furthermore, this invention enables the use of smaller conventional electrical safety devices (e.g., fuses) without the need to upgrade to larger devices with higher ratings.

[0015] See Figures 1 to 3 An exemplary tool 100 (such as a cordless ratchet tool) incorporating one embodiment of the present invention includes a main tool housing 102 and an output assembly 104 (such as a ratchet head assembly). The tool housing 102 may include a first housing portion and a second housing portion joined together in a clamshell manner and securely connected to the output assembly 104. The tool housing 102 may enclose or house an electric motor 114. Figure 2 and Figure 3 (shown in the image), controller 116 ( Figure 2 and Figure 3 (shown in the image), switch assembly 118 ( Figure 2and Figure 3 (shown in the image), a display with buttons for configuration and setting tools, and one or more indicators 122. Figure 2 and Figure 3 (as shown in the diagram) such as, for example, light-emitting diodes, electrical safety devices 124 ( Figure 2 and Figure 3 (As shown in the diagram) (such as, for example, a fuse) and other components for operating the tool. The tool housing 102 may also include a textured or knurled handle to improve the user's grip on the tool 100 during use.

[0016] For example, output assembly 104 includes a drive portion 106 that includes a drive flange 108. The drive flange 108 is adapted to apply torque to a workpiece (such as a fastener) via an adapter, drill bit, or sleeve (e.g., a two-way ratchet square or hexagonal actuator) coupled to the drive flange 108. As shown, the drive flange 108 is a "male" connector designed to insert or mat with a female pairing. However, the drive portion 106 may alternatively include a "female" connector designed to mat with a male pairing. The drive portion 106 may also be configured to directly engage a workpiece without coupling to an adapter, drill bit, or sleeve. The rotation direction of the drive portion 106 / drive flange 108 can be selected as a first rotation direction or a second rotation direction (such as clockwise or counterclockwise) by rotating a selector switch.

[0017] Tool 100 includes a trigger 110 that can be actuated by a user to operate tool 100. For example, a user can press the trigger 110 inward to selectively draw power from power source 120, causing motor 114 to provide torque to output assembly 104 and rotate drive flange 112 in the desired rotational direction. Trigger 110 can also be operatively coupled to a switching mechanism 118 adapted to supply power from power source 120 to motor 114 when trigger 110 is actuated. Any suitable trigger 110 or switch can be implemented without departing from the spirit and scope of the invention. For example, trigger 110 can also be biased such that trigger 110 can be pressed inward relative to tool 100 to operate tool 100, and releasing trigger 110 allows trigger 110 to move outward relative to tool 100 to stop tool 100 from operating by the biasing characteristic of trigger 110. Trigger 110 and switching mechanism 118 can also be variable speed mechanisms. In this respect, when the trigger 110 is actuated or pressed, the further the trigger 110 is pressed down, the faster the motor will work.

[0018] Motor 114 may be disposed within tool housing 102 and adapted to operatively engage output assembly 104, and may provide torque to tool 100, thereby providing torque to drive section 106 / drive flange 108. Motor 114 may be a brushless or brushed motor or any other suitable motor. Power supply 120 may be associated with tool 100 to provide power to tool 100 to operate the motor. In one embodiment, power supply 120 may be housed in end 112 of tool housing 102 opposite output assembly 104, in the middle of tool 100, or in any other part of tool 100 / tool ​​housing 102. Power supply 120 may also be an external component not housed in tool 100 but operatively coupled to tool 100, for example, via wired or wireless means. In one embodiment, power supply 120 is a removable rechargeable battery adapted to be disposed in end of tool housing 102 and electrically coupled to corresponding terminals of tool 100.

[0019] The controller 116 may be operatively coupled to one or more of the power supply 120, the switching mechanism 118, and the motor 114. The controller 116 may include a central processing unit (CPU) for processing data and computer-readable instructions, and memory for storing data and instructions. The memory may include volatile random access memory (RAM), non-volatile read-only memory (ROM), and / or other types of memory. It may also include data storage components for storing data and controller / processor-executable instructions (e.g., instructions for the operation and execution of tool 100). The data storage components may include one or more non-volatile solid-state storage devices (such as flash memory, read-only memory (ROM), magnetoresistive RAM (MRAM), ferroelectric RAM (FRAM), phase-change memory, etc.).

[0020] Computer instructions for operating tool 100 and its various components can be executed by controller 116 using memory as temporary "working" memory during runtime. The computer instructions can be stored in non-volatile memory, storage devices, or external devices in a non-transitory manner. Alternatively, in addition to software or as a replacement for software, some executable instructions can be embedded in hardware or firmware.

[0021] An electrical safety device 124 (such as a fuse) is connected in series with the power supply from power source 120 to controller 116 to provide overcurrent protection to controller 116, motor 114, and / or other electrical components of tool 100. When too much current flows through electrical safety device 124 due to a fault event (such as a short circuit), electrical safety device 124 blocks or interrupts the current, thereby shutting down motor 114 and protecting other components. Once electrical safety device 124 has been activated, it is an open circuit and must be replaced or rewired.

[0022] For example, controller 116 can implement the method described herein. When trigger 110 is actuated, power is supplied to motor 114, causing output component 104 to operate and overcurrent protection to activate. During operation of tool 100, controller 116 measures the current through electrical safety device 124 at time intervals (such as, for example, every 1 microsecond or every 1 millisecond). For example, a high-pass filter can be used to filter the current and / or accumulated heat energy through electrical safety device 124 to remove slowly varying amounts of current and / or accumulated heat energy. Controller 116 implements this by repeatedly applying the formula current × current × time (I0) at each time interval. 2 The controller 116 determines the accumulated thermal energy passing through the electrical safety device 124 using the parameter ×t). The controller 116 compares the accumulated thermal energy with a threshold value. This threshold value is based on the I value that the electrical safety device 124 can or should be able to withstand. 2 The minimum number of ×t pulses and the specifications provided by the manufacturer of electrical safety device 124. If the accumulated heat energy exceeds a threshold, controller 116 stops or interrupts the supply of power from power source 120 to motor 114, thereby shutting down motor 114. This prevents electrical safety device 124 from prematurely and / or unnecessarily blocking or interrupting current from the power source. Tool 100 can also activate indicator 122 to indicate a fault to the user. Indicator 122 can be any type of indicator (such as a light-emitting diode (LED), haptic actuator, display, etc.) capable of indicating a fault to the user. Furthermore, the indicator can be turned off after a predetermined amount of time.

[0023] See Figure 4 This describes an operational method 200 of an exemplary tool 100 incorporating one embodiment of the present invention. As shown in step 202, overcurrent protection is initiated when the trigger is actuated. As shown in step 204, once the trigger is actuated, the tool (e.g., via controller 116) measures the current through the electrical safety device 124 at time intervals (e.g., every 1 microsecond or every 1 millisecond). As shown in step 206, the tool (e.g., via controller 116) determines the accumulated thermal energy through the electrical safety device 124. For example, as described above, the tool may use a high-pass filter to filter the current and / or accumulated thermal energy. As shown in step 208, the tool (e.g., via controller 116) compares the accumulated thermal energy (which may be filtered accumulated thermal energy) with a threshold. As shown in step 210, when the accumulated thermal energy is below the threshold, the tool (e.g., via controller 116) continues to operate normally and continues to measure the current and calculate the accumulated thermal energy at predetermined time intervals until the trigger is released. When the accumulated heat energy equals or exceeds a threshold, the tool (such as via controller 116) terminates or stops supplying power to the motor, as shown in step 212, and may also activate an indicator, as shown in step 214, until the trigger is released.

[0024] As described herein, an exemplary tool 100 incorporating one embodiment of the invention is a ratchet wrench. However, it should be recognized that the invention can be used with any type of handheld power tool, including but not limited to electric or motorized tools (such as drills, planers, or impact wrenches, ratchet wrenches, screwdrivers, or other power tools) powered by an external power source (such as a wall socket and / or generator socket) or a battery. Furthermore, although the invention is exemplarily described for use with a tool, the invention can be used with or incorporated into any electric motor device.

[0025] As used herein, the term "connection" and its functional equivalents are not intended to be limited to a direct mechanical connection of two or more parts. Rather, the term "connection" and its functional equivalents are intended to refer to any direct or indirect mechanical, electrical, or chemical connection between two or more objects, features, workpieces, and / or environmental substances. In some instances, "connection" is also intended to indicate that one object is integral with another. As used herein, unless otherwise specified, the terms "a" or "some" may include one or more items.

[0026] The description and figures above are provided by way of example only and not as a limitation. While specific embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications can be made without departing from the broader aspects of the inventors' contributions. The actual scope of protection claimed, when viewed from the proper perspective of the prior art, is intended to be defined by the following claims.

Claims

1. A method of operating an electric tool, the electric tool comprising a motor, an output assembly adapted to be driven by the motor, a power supply adapted to supply power to the motor, and a controller operably coupled to the motor and the power supply, the method comprising: When power is supplied to the motor, the amount of accumulated thermal energy through an electrical safety device is determined, wherein the electrical safety device is operatively connected in series with the power supply connection from the power source to the controller; The amount of accumulated heat energy is compared with a threshold limit; as well as When the accumulated heat energy reaches or exceeds the threshold limit, the power supply to the motor is stopped.

2. The method according to claim 1, further comprising: The current flowing through the electrical safety device is measured at predetermined time intervals.

3. The method of claim 2, wherein the step of determining the amount of accumulated thermal energy through the electrical safety device is based on the amount of current passing through the electrical safety device at predetermined time intervals.

4. The method of claim 2, further comprising: The current is filtered by the filter of the power tool.

5. The method of claim 4, wherein the filter is a high-pass filter.

6. The method of claim 1, further comprising: The amount of accumulated heat energy is filtered by the filter of the power tool.

7. The method of claim 6, wherein the filter is a high-pass filter.

8. The method of claim 1, further comprising: When the amount of accumulated heat energy is below the threshold limit, power supply to the motor is permitted.

9. The method of claim 1, wherein when the trigger of the power tool is actuated, the step of determining the amount of accumulated thermal energy through the electrical safety device is initiated.

10. An electric tool having a motor, a power supply adapted to supply power to the motor, and an output assembly adapted to be driven by the motor, the electric tool comprising; A controller operatively connected to the motor and the power supply; as well as An electrical safety device, which is operatively connected in series with the power supply connection from the power source to the controller; The controller is adapted to: When power is supplied to the motor, the amount of accumulated thermal energy through the electrical safety device is determined; The amount of accumulated thermal energy is compared with a threshold limit; as well as When the amount of accumulated heat energy reaches or exceeds the threshold limit, the power supply to the motor is stopped.

11. The power tool of claim 10, wherein the controller is further adapted to: measure the amount of current passing through the electrical safety device at predetermined time intervals.

12. The power tool of claim 11, wherein the controller is further adapted to: determine the amount of accumulated heat energy passing through the electrical safety device based on the respective current amounts passing through the electrical safety device at predetermined time intervals.

13. The power tool of claim 11, further comprising: A filter suitable for filtering the current.

14. The power tool of claim 13, wherein the filter is a high-pass filter.

15. The power tool of claim 10, further comprising: A filter suitable for filtering the amount of accumulated heat energy.

16. The power tool of claim 15, wherein the filter is a high-pass filter.

17. The power tool of claim 10, wherein the controller is further adapted to: allow power to be supplied to the motor when the amount of accumulated thermal energy is below the threshold limit.

18. The power tool of claim 10, wherein the controller is further adapted to: determine the amount of accumulated thermal energy through the electrical safety device when the trigger of the power tool is actuated.

19. The power tool of claim 10, wherein the controller includes a data storage component adapted to store executable instructions.

20. The power tool of claim 19, wherein the data storage component is a ferroelectric random access memory.

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