Off-control detection device and handheld electric tool

Abstract

The utility model provides an out-of-control detection device and a handheld electric tool, and relates to the technical field of handheld electric tools, the out-of-control detection device is applied to the handheld electric tool, the out-of-control detection device comprises a detection circuit, a logic circuit and a triode, an induction area of the detection circuit is used for being arranged on the outer surface of a handle of the handheld electric tool, and the logic circuit is arranged on the outer surface of the detection circuit. A signal output end of the detection circuit is connected with an input end of the logic circuit, an output end of the logic circuit is connected with a base electrode of the triode, a collector electrode of the triode is connected with a power supply, and an emitter electrode of the triode is connected with a motor of the handheld tool. According to the utility model, the use safety of the handheld electric tool can be effectively improved.

Description

Technical Field

[0001] This utility model relates to the field of handheld power tool technology, and more specifically, to a disengagement detection device and a handheld power tool. Background Technology

[0002] With the development of technology, handheld power tools have become increasingly popular and integrated into all aspects of daily production operations. Handheld power tools require operators to hold the handle to operate them, so that the working part can be precisely applied to the work surface to carry out tasks such as cutting, grinding, and drilling. A firm grip is not only related to the accuracy of operation, but also crucial for safety.

[0003] However, in actual use, when the working part of a handheld power tool hits a hard object, the torque generated by the motor in an instant exceeds the limit that the hand can hold, which may cause the power tool to slip out of the hand. The power tool that continues to run after slipping out of the hand may cause injury to people around. Utility Model Content

[0004] The problem this invention addresses is: how to improve the safety of using handheld power tools.

[0005] To address the aforementioned problems, this utility model provides a disengagement detection device and a handheld power tool.

[0006] In a first aspect, this utility model provides a disengagement detection device for use in handheld power tools. The disengagement detection device includes a detection circuit, a logic circuit, and a transistor. The sensing area of ​​the detection circuit is disposed on the outer surface of the handle of the handheld power tool. The signal output terminal of the detection circuit is connected to the input terminal of the logic circuit. The output terminal of the logic circuit is connected to the base of the transistor. The collector of the transistor is connected to a power supply, and the emitter of the transistor is connected to the motor of the handheld power tool.

[0007] Optionally, the detection circuit includes a DC power supply, an oscillator, and a capacitive sensing element. The positive terminal of the power supply is connected to a first end of the oscillator, and the second end of the oscillator is connected to the negative terminal of the DC power supply. The sensing area of ​​the capacitive sensing element is disposed on the outer surface of the handle of the handheld power tool. The pin of the capacitive sensing element is connected to the first end of the oscillator, and the first end of the oscillator is connected to the input terminal of the logic circuit.

[0008] Optionally, the oscillator includes a first resistor and a capacitor. One end of the first resistor serves as the first terminal of the oscillator and is connected to the positive terminal of the DC power supply. The other end of the first resistor serves as the second terminal of the oscillator and is connected to the negative terminal of the DC power supply. One end of the capacitor is connected to one end of the first resistor, and the other end of the capacitor is connected to the other end of the first resistor.

[0009] Optionally, the device further includes a first switch connected in series between the positive terminal of the DC power supply and the first terminal of the oscillator.

[0010] Optionally, the device further includes an inductor connected in series between the positive terminal of the power supply and the first switch.

[0011] Optionally, the device further includes a second switch connected in series between the output of the logic circuit and the base of the transistor.

[0012] Optionally, the device further includes a second resistor connected in series between the second switch and the base of the transistor.

[0013] Optionally, the device may further include a third resistor connected in series between the power supply and the collector of the transistor.

[0014] Optionally, the device further includes a fourth resistor, one end of which is connected to the base of the transistor, and the other end of which is used to connect to a power supply.

[0015] Secondly, this utility model provides a handheld power tool, including the disengagement detection device described above.

[0016] The beneficial effects of this detachment detection device are as follows: The sensing area of ​​the detection circuit is located on the outer surface of the handle, continuously monitoring the user's grip. When the user accidentally drops the tool due to unforeseen circumstances, such as sudden hand weakness or a sudden external impact, the detection circuit immediately detects this change and transmits the signal sequentially to the logic circuit and the transistor. The transistor then disconnects the motor from the power supply, instantly stopping the tool and preventing it from swinging uncontrollably and potentially injuring those nearby. This significantly reduces the risk of injury to personnel on-site and improves the safety of using handheld power tools. Furthermore, it prevents the handheld power tool from accidentally starting when unattended, preventing damage to surrounding equipment, fires, or other accidental injuries due to loss of control, thus enhancing the safety of using handheld power tools in complex working conditions. Attached Figure Description

[0017] Figure 1This is a circuit diagram of the off-control detection device in an embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the handheld power tool in the embodiment of this utility model.

[0019] Explanation of reference numerals in the attached figures:

[0020] U - DC power supply; L - Inductor; T - Sensing area; C - Capacitor; A - Logic circuit; Q - Transistor; V - Power supply; M - Motor; S1 - First switch; S2 - Second switch; R1 - First resistor; R2 - Second resistor; R3 - Third resistor; R4 - Fourth resistor; B - Handheld power tool. Detailed Implementation

[0021] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Although some embodiments of this utility model are shown in the drawings, it should be understood that this utility model can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this utility model. It should be understood that the drawings and embodiments of this utility model are for illustrative purposes only and are not intended to limit the scope of protection of this utility model.

[0022] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this utility model are only used to distinguish different devices, modules, or units, and are not used to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0023] It should be noted that the terms "one" and "multiple" used in this utility model are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0024] In related technologies, the normal operating mode of handheld power tools involves the user holding the tool or using other parts of their body to stabilize its relative position. The tool's mechanical moving parts achieve their function through continuous or reciprocating motion. Most power tools are powered by a motor. However, some situations can arise during actual use. For example, when the tool's working part suddenly encounters a particularly hard object (like a rock or steel bar), the tool's head may not be able to immediately and effectively cut the contact surface, causing it to suddenly seize and stop rotating. However, the motor continues to output power as before the abnormality, resulting in torque remaining in the mechanical part. Furthermore, the sudden seizure of the working part causes the motor torque to be much greater than during normal operation; that is, the rotational torque acting on the mechanical part suddenly increases dramatically. According to the principle of force interaction, the tool body and handheld part need a reaction force opposite to the direction of the torque to keep the tool body fixed. However, this seizure is rapid, unpredictable, and involves a sudden increase in torque, often leaving the user no time to react, causing the user to lose their grip and the tool to slip from their hand. Tools that continue to operate after being released from the hand are likely to come into impact with the user's body, potentially causing injury. Furthermore, prolonged use of tools can lead to fatigue, reducing grip strength and causing the tool to be accidentally dropped. If the tool's mechanical parts are still operating at this time, it could also cause injury.

[0025] To address the problems existing in the aforementioned related technologies, this utility model provides a disengagement detection device and a handheld power tool.

[0026] Combination Figure 1 and 2 As shown in the figure, this utility model provides a disengagement detection device applied to a handheld power tool B. The disengagement detection device includes a detection circuit, a logic circuit A, and a transistor Q. The sensing area T of the detection circuit is disposed on the outer surface of the handle of the handheld power tool B. The signal output terminal of the detection circuit is connected to the input terminal of the logic circuit A. The output terminal of the logic circuit A is connected to the base of the transistor Q. The collector of the transistor Q is connected to the power supply V. The emitter of the transistor Q is connected to the motor M of the handheld power tool.

[0027] Specifically, the sensing area T of the detection circuit is located on the outer surface of the handle of the handheld power tool B. When operating the tool, the user must hold it and keep it stable, allowing the sensing area to directly contact the user. Under normal circumstances, there is a certain electrical connection between the human body and the detection circuit. When the user holds the handle normally, the detection circuit is in a relatively stable working state, and its electrical parameters are affected by the capacitance C and resistance of the human body. However, if the tool becomes detached, for example, due to the working part hitting a hard object causing an abnormal increase in the torque of the motor M, and the user suddenly releases their grip, the electrical environment of the detection circuit will immediately change. This change can be quickly captured by the detection circuit and converted into a corresponding electrical signal. The signal output terminal of the detection circuit is connected to the input terminal of the logic circuit A. The logic circuit A processes the received signal from the detection circuit, generating a corresponding output signal based on pre-set logic rules. For example, it generates a high-level signal and a low-level signal based on the input signal; that is, a high-level signal is output when there is no detachment, and a low-level signal is generated when detachment occurs. The output of logic circuit A is connected to the base of transistor Q. Transistor Q controls the on / off state of the power supply V to motor M. When logic circuit A determines that no disconnection has occurred, the handheld power tool B can operate normally. Logic circuit A outputs a high-level signal to the base of transistor Q. For an NPN transistor Q, a high-level input to the base will conduct the collector and emitter. Since the collector of transistor Q is connected to the power supply V and the emitter is connected to the motor M, when the collector and emitter are conducting, the power from the power supply V is supplied to motor M through the collector and emitter of transistor Q, thus maintaining the operating state of motor M. In other words, during normal operation, transistor Q is in the conducting state to ensure a stable power supply V to motor M, allowing the handheld power tool to operate normally. However, once a disconnection signal is received, logic circuit A outputs a low-level signal to the base of transistor Q, thereby cutting off the collector and emitter of transistor Q, disconnecting motor M from power supply V, and immediately stopping motor M.

[0028] In this embodiment, the sensing area T of the detection circuit is located on the outer surface of the handle, continuously monitoring the user's grip. When the user accidentally drops the tool, the detection circuit immediately detects this change and transmits the signal sequentially to the logic circuit A and the transistor Q. Finally, the transistor Q disconnects the motor M from the power supply V, stopping its operation and preventing the handheld power tool B from swinging uncontrollably and causing injury to surrounding personnel. This significantly reduces the risk of injury to personnel on site and improves the safety of the handheld power tool B during use. Simultaneously, it also prevents the handheld power tool B from accidentally starting when no one is holding it, preventing the tool from damaging surrounding equipment, causing fires, or other accidental injuries due to loss of control, thus enhancing the safety of using the handheld power tool B in complex working conditions.

[0029] Optionally, such as Figure 1 As shown, the detection circuit includes a DC power supply 11, an oscillator, and a C-type capacitor sensing element. The positive terminal of the power supply V is connected to the first end of the oscillator, and the second end of the oscillator is connected to the negative terminal of the DC power supply 11. The sensing area T of the C-type capacitor sensing element is used to be disposed on the outer surface of the handle of the handheld power tool B. The pin of the C-type capacitor sensing element is connected to the first end of the oscillator, and the first end of the oscillator is connected to the input terminal of the logic circuit A.

[0030] In this optional embodiment, the DC power supply 11 serves as the energy supply unit for the entire detection circuit, providing stable power for the oscillator's operation and ensuring continuous and stable circuit operation. The first end of the oscillator is connected to the positive terminal of the DC power supply 11, and the second end of the oscillator is connected to the negative terminal of the DC power supply 11. The DC power output from the DC power supply 11 ensures that the oscillation frequency of the subsequent oscillator remains at a relatively stable reference level, preventing significant deviations due to fluctuations in the power supply V. The sensing area T of the capacitive C-type sensing element is located on the outer surface of the handle of the handheld power tool B, directly generating a capacitive C coupling relationship with the user's hand. The pins of the capacitive C-type sensing element are connected to one end of the oscillator. When the user holds the tool handle, the human body, as a conductor, changes the original capacitance of the capacitive C-type sensing element. When a person touches the device, it's equivalent to introducing an additional conductor into the capacitor-type sensing element (C), increasing its capacitance. This change in capacitance, in turn, affects the oscillation frequency of the connected oscillator. This chain reaction of capacitance (C) and frequency changes caused by the human gripping action becomes a key indicator for detecting whether the device is being held. This causes the detection circuit to generate a corresponding signal, which is then connected to the input of logic circuit A via the first terminal of the oscillator. The signal is transmitted to logic circuit A, such as the oscillation frequency. Based on the received signal, logic circuit A can determine whether the handheld power tool B is being held. Based on this determination, it can quickly cut off the power supply (V) if the handheld power tool B is released, preventing accidents and improving the safety of using the handheld power tool B.

[0031] For example, logic circuit A may include a frequency counter and a comparator. When a human body comes into contact with the sensing area T, it is equivalent to connecting a capacitor in parallel across capacitor C in detection circuit A, thereby increasing the capacitance in the oscillator and thus reducing the oscillation frequency. That is, when the human body is in contact with the sensing area T, a lower frequency is output. When the human body leaves the sensing area T, the capacitance in the circuit returns to its initial state, the capacitance in the oscillator decreases, and thus the oscillation frequency of the oscillator returns to a relatively higher frequency. Therefore, logic circuit A may include a frequency counter and a comparator. The frequency counter records the oscillation frequency in the detection circuit, and the comparator compares the recorded value with a set value to determine whether the human body is in contact with the sensing area T. For example, if a higher input signal frequency is detected that exceeds the set value, it indicates that the human body has left the sensing area T. At this time, the comparator outputs a low level to the base of transistor Q based on the comparison result, cutting off the collector and transmitter of transistor Q, thereby de-energizing motor M. The frequency counter and comparator are existing technologies and will not be described in detail here.

[0032] Optionally, such as Figure 1As shown, the oscillator includes a first resistor R1 and a capacitor C. One end of the first resistor R1 serves as the first terminal of the oscillator and is connected to the positive terminal of the DC power supply U. The other end of the first resistor R1 serves as the second terminal of the oscillator and is connected to the negative terminal of the DC power supply U. One end of the capacitor C is connected to one end of the first resistor R1, and the other end of the capacitor C is connected to the other end of the first resistor R1.

[0033] Specifically, the first resistor R1 and capacitor C in the oscillator are connected in parallel and then connected to the DC power supply U. That is, one end of the first resistor R1 and one end of the capacitor C are connected as the first terminal of the oscillator and connected to the positive terminal of the DC power supply U. The other end of the first resistor R1 and the other end of the capacitor C are connected as the second terminal of the oscillator and connected to the negative terminal of the DC power supply U. When the circuit is turned on, the current will start from the positive terminal of the power supply V and charge the capacitor C. At this time, the voltage across the capacitor C will gradually rise. Since the voltage across the capacitor C cannot change abruptly, the current is large at the beginning of charging. As charge accumulates on the plates of the capacitor C, the voltage across the capacitor C approaches the voltage of the power supply V, and the charging current gradually decreases. When a hand approaches the sensing area T, it's equivalent to connecting the capacitance C between the human body and the ground in parallel, thus increasing the total capacitance C. This changes the voltage across the oscillator, allowing for a quick determination of whether the human body has touched the sensing area T. The changed voltage value is then sent to logic circuit A. When logic circuit A determines that the received voltage matches the voltage at which the human body is in contact with the sensing area T, it outputs a high level to the base of transistor Q to maintain power supply V for the motor M in the handheld power tool B. Conversely, when the received voltage is the normal voltage of the oscillator (no human contact), it outputs a low level to the base of transistor Q, cutting off power supply V to the motor M. This prevents the handheld power tool B from continuing to rotate after being released from the hand, thus avoiding injury to nearby personnel and damage to surrounding facilities, and improving the safety of using the handheld power tool B.

[0034] Optionally, such as Figure 1 As shown, the device also includes a first switch S1, which is connected in series between the positive terminal of the DC power supply U and the first terminal of the oscillator.

[0035] In this optional embodiment, a first switch S1 is connected in series between the positive terminal of the DC power supply U and the first terminal of the oscillator. The first switch S1 controls the on / off state of the detection circuit. When it is not necessary to detect whether the handheld power tool B is being held, the first switch S1 can be set to the open state, stopping the power supply to the oscillator. When it is necessary to detect whether someone is holding the tool, the first switch S1 can be closed, allowing the DC power supply U of the detection circuit to power the oscillator. Furthermore, the state of the detection circuit can be adjusted via the first switch S1, thereby improving the adaptability of the detachment detection device to different working conditions.

[0036] Optionally, such as Figure 1 As shown, the device also includes an inductor L, which is connected in series between the positive terminal of the power supply V and the first switch S1.

[0037] In this optional embodiment, an inductor L is connected in series between the positive terminal of the power supply V and the first switch S1. The series inductor L can limit sudden changes in current in the detection circuit, avoiding large fluctuations in current from impacting circuit components and affecting the signal output to the logic circuit A. Thus, the logic circuit A can accurately control the switching of the transistor according to the signal, further ensuring the accuracy of control over the handheld power tool B and improving the safety of using the handheld power tool B.

[0038] Optionally, such as Figure 1 As shown, the device also includes a second switch S2, which is connected in series between the output of the logic circuit A and the base of the transistor Q.

[0039] In this optional embodiment, by connecting a second switch S2 in series between the output terminal of logic circuit A and the base of the transistor, the power supply to the handheld power tool B can be controlled by the second switch S2 in an emergency. For example, if logic circuit A or the detection circuit is abnormal, the power to the handheld power tool B can be cut off by disconnecting the second switch S2, ensuring the safety of the handheld power tool B during use. At the same time, the second switch S2 can also be used as a switch for the handheld power tool B, allowing manual control of the start and stop of the handheld power tool B.

[0040] Optionally, such as Figure 1 As shown, the device also includes a second resistor R2, which is connected in series between the second switch S2 and the base of the transistor Q.

[0041] In this optional embodiment, by connecting a second resistor R2 in series between the second switch S2 and the base of the transistor Q, it is possible to prevent the transistor Q from being damaged by excessive base current and ensure that the current flowing into the base is within the range that the transistor Q can withstand.

[0042] Optionally, such as Figure 1 As shown, the device also includes a third resistor R3, which is connected in series between the power supply V and the collector of the transistor Q.

[0043] Optionally, such as Figure 1 As shown, the device also includes a fourth resistor, one end of which is connected to the base of the transistor Q, and the other end of which is used to connect to the power supply V.

[0044] In this optional embodiment, a third resistor R3 is connected in series between the power supply V and the collector of transistor Q. The third resistor R3 limits the collector current, preventing excessive current from damaging transistor Q and other components. One end of a fourth resistor R4 is connected to the base of transistor Q, and the other end is connected to the power supply V. The fourth resistor R4 provides a suitable bias voltage to the base, while also helping to regulate current and voltage, compensate for temperature changes, and thus improve circuit stability.

[0045] This utility model provides a handheld power tool, including the off-control detection device described above.

[0046] The handheld power tool in this embodiment has the same advantages over the prior art as the aforementioned off-control detection device, and will not be repeated here.

[0047] Although the present invention has been disclosed above, its protection scope is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the protection scope of the present invention.

Claims

1. A runaway detection device, characterized in that, The application is applied to a handheld electric tool, and the out-of-control detection device comprises a detection circuit, a logic circuit and a triode, the sensing area of the detection circuit is arranged on the outer surface of the handle of the handheld electric tool, the signal output end of the detection circuit is connected with the input end of the logic circuit, the output end of the logic circuit is connected with the base of the triode, the collector of the triode is connected with the power supply, and the emitter of the triode is connected with the motor of the handheld electric tool.

2. The off-control detection device according to claim 1, characterized in that, The detection circuit comprises a direct current power supply, an oscillator and a capacitive sensing element, the positive pole of the power supply is connected with the first end of the oscillator, the second end of the oscillator is connected with the negative pole of the direct current power supply, the sensing area of the capacitive sensing element is arranged on the outer surface of the handle of the handheld electric tool, the pin of the capacitive sensing element is connected with the first end of the oscillator, and the first end of the oscillator is connected with the input end of the logic circuit.

3. The off-control detection device according to claim 2, characterized in that, The oscillator comprises a first resistor and a capacitor, one end of the first resistor is connected with the positive pole of the direct current power supply as the first end of the oscillator, the other end of the first resistor is connected with the negative pole of the direct current power supply as the second end of the oscillator, one end of the capacitor is connected with one end of the first resistor, and the other end of the capacitor is connected with the other end of the first resistor.

4. The off-control detection device according to claim 2, characterized in that, A first switch is further arranged in series between the positive pole of the direct current power supply and the first end of the oscillator.

5. The off-control detection device according to claim 4, characterized in that, An inductor is further arranged in series between the positive pole of the power supply and the first switch.

6. The off control detection apparatus according to claim 1, characterized by A second switch is further arranged in series between the output end of the logic circuit and the base of the triode.

7. The off control detection apparatus according to claim 6, characterized by A second resistor is further arranged in series between the second switch and the base of the triode.

8. The off control detection apparatus according to claim 7, characterized by A third resistor is further arranged in series between the power supply and the collector of the triode.

9. The off control detection apparatus according to claim 8, characterized by A fourth resistor is further arranged, one end of the fourth resistor is connected with the base of the triode, and the other end of the fourth resistor is connected with the power supply.

10. A hand-held power tool, characterized in that The out-of-control detection device is arranged in the handheld electric tool. The application is applied to a handheld electric tool, and the out-of-control detection device comprises a detection circuit, a logic circuit and a triode, the sensing area of the detection circuit is arranged on the outer surface of the handle of the handheld electric tool, the signal output end of the detection circuit is connected with the input end of the logic circuit, the output end of the logic circuit is connected with the base of the triode, the collector of the triode is connected with the power supply, and the emitter of the triode is connected with the motor of the handheld electric tool.

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