A low-power on / off circuit for power tools

Abstract

The present invention relates to the technical field of electrical switch control, and provides a low-power on-off circuit for power tools. A first trigger module is connected in series between the slide switch and the third switch module to control in sequence by hardware startup and software startup. While achieving rapid startup, the normal operation of the circuit is ensured. And after a preset time period, a shutdown signal is output to control the third switch module to stop working, so that even if the startup circuit corresponding to the first switch module is always connected to the battery through the slide switch after being powered on, it can stop working through the third switch module, so that the energized circuit of the startup circuit only requires an extremely low static current, thereby greatly reducing the startup energy consumption of the circuit, effectively increasing the battery life of the battery pack, and avoiding the risk of battery pack scrapping caused by forgetting to turn off the slide switch.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical switch control, and particularly to a low-power on-off circuit for power tools. Background Art

[0002] For the one-key on-off circuits of most power tools on the market, self-returning tactile switches or slide switches are used as braking elements, and low power consumption can be achieved after shutdown.

[0003] In a conventional use scenario, if a power tool (for example: Bosch 12V lithium battery grinder) uses a slide switch as a braking element, low power consumption can be achieved when the user is in a normal shutdown state; however, when the power tool has low battery power and is powered off, if the user forgets to slide the slide switch to the off state, even if the MCU disconnects the power output of the electrical load, since the battery pack still outputs a static current to the load power supply circuit to maintain the standby state, the circuit will continue to consume power.

[0004] In this case, if the user does not remove the battery pack in time, the battery pack will be depleted after a period of time. If the user does not remove the battery pack for more than 3 months for a long time, there may be a risk of battery pack scrapping. Summary of the Invention

[0005] The present invention provides a low-power on-off circuit for power tools, which solves the technical problem that the existing on-off circuit is limited to the physical control of the braking switch. If the power is not cut off in time, the battery pack will continue to consume power, which may lead to the scrapping of the battery pack.

[0006] To solve the above technical problems, the present invention provides a low-power on-off circuit for power tools, including:

[0007] A first switch module connected in series on the main power supply loop;

[0008] A second switch module and a third switch module connected to the control end of the first switch module;

[0009] A first trigger module and a second trigger module connected to the slide switch;

[0010] A main controller connected to the second switch module, the third switch module, and the second trigger module;

[0011] The main controller collects the state feedback of the slide switch through the second trigger module, or collects the state change of the third switch module; and then drives the first switch module to conduct or disconnect the main power supply loop by controlling the state change of the second switch module.

[0012] After the first trigger module is connected to the battery pack power supply through the sliding switch, it outputs a start signal to control the third switch module to drive the first switch module to conduct the main power supply circuit; and after a preset time period, it outputs a shutdown signal to control the third switch module to stop working, and the first trigger module enters the low-power standby state.

[0013] In this basic solution, a first trigger module is connected in series between the sliding switch and the third switch module to control in sequence by hardware startup and software startup. While achieving fast startup, it ensures the normal operation of the circuit; and by outputting a shutdown signal to control the third switch module to stop working after a preset time period, even if the startup circuit corresponding to the first switch module is continuously connected to the battery through the sliding switch after being powered on, it can stop working through the third switch module, so that the power-on circuit of the startup circuit only requires a very low static current, thereby greatly reducing the startup energy consumption of the circuit, effectively increasing the battery life of the battery pack, and avoiding the risk of battery pack scrapping caused by forgetting to turn off the sliding switch.

[0014] In a further implementation, the sliding switch includes a first static contact, a second static contact, and a moving contact. One end of the moving contact is electrically connected to the battery pack, and the other end is connected to the first static contact or the second static contact; the first static contact is connected to the input end of the first trigger module, and the second static contact is connected to the input end of the second trigger module.

[0015] In a further implementation, the first trigger module includes NAND gate U1A, NAND gate U1B, resistor R1, capacitor C1, and capacitor C2; one end of resistor R1 is connected to the first static contact of the sliding switch, and the other end is connected to the input end of NAND gate U1A; the input end of NAND gate U1B is connected to the output end of NAND gate U1A, and the output end is connected to the control end of the third switch module; one end of capacitor C1 is connected to the other end of resistor R1, and the other end is grounded; one end of capacitor C2 is connected to the ADD pin of NAND gate U1A, and the other end is grounded;

[0016] When the moving contact of the sliding switch is connected to the first static contact, the battery pack charges capacitor C1 through resistor R1. Since the voltage across capacitor C1 does not change suddenly, at this time, a low level is input to the input end of NAND gate U1A, then the output end of NAND gate U1A outputs a low level to the input end of NAND gate U1B, and the output end of NAND gate U1B outputs a low level to control the third switch module to drive the first switch module to conduct the main power supply circuit;

[0017] The main controller detects the state change of the third switch module, and then controls the second switch module to replace the third switch module to drive the first switch module to turn on the main power supply circuit.

[0018] When the capacitor C1 is fully charged, a high level is input to the input terminal of the NAND gate U1A, then a high level is output from the output terminal of the NAND gate U1A to the input terminal of the NAND gate U1B, and a high level is output from the output terminal of the NAND gate U1B to control the first switch module to stop working and enter the low-power state.

[0019] This solution takes a dual NAND gate (NAND gate U1A and NAND gate U1B) and a capacitor as the core, uses the dual NAND gate to execute the signal trigger for power access, and combines the charge storage ability of the capacitor. When the moving contact of the sliding switch is connected to the first static contact, the dual NAND gate is triggered to start quickly; then when the capacitor C1 is fully charged, the input signal of the dual NAND gate is changed, thus completing a signal transformation for one start; finally, if the user forgets to turn off the sliding switch, since the static current of the dual NAND gate is maintained at 4 μA, the power consumption of the battery pack can be greatly reduced, and it can still be maintained for more than 6 months even after the power tool has low power, avoiding the risk of battery pack scrapping.

[0020] In a further embodiment, the second trigger module includes a signal trigger module, and the signal trigger module includes a switching transistor Q1A, a resistor R2, a resistor R3, a resistor R4, and a capacitor C3; the first end of the switching transistor Q1A is connected to the power supply terminal through the resistor R2, the second end is grounded, and the control end is connected to the second static contact of the sliding switch through the resistor R3; one end of the capacitor C3 is connected to the second static contact of the sliding switch, and the other end is grounded; one end of the resistor R4 is connected to the control end of the switching transistor Q1A, and the other end is connected; the first end of the switching transistor Q1A is also connected to the main controller;

[0021] When the moving contact of the sliding switch is connected to the second static contact, the switching transistor Q1A is turned on, and a shutdown signal is output to the main controller. The main controller controls the second switch module to drive the first switch module to disconnect the main power supply circuit, performing physical shutdown and software shutdown.

[0022] This solution connects a signal trigger module with the switching transistor Q1A as the core at the second static contact of the sliding switch to monitor in real time whether the sliding switch slides to the second static contact, realizing real-time and low-power monitoring of the shutdown signal.

[0023] In a further embodiment, the second trigger module further includes a discharge module, and the discharge module includes a switching transistor Q1B, a resistor R5, and a resistor R6; a first end of the switching transistor Q1B is connected to one end of a capacitor C2, a second end is grounded, and a control end is connected to the second stationary contact through the resistor R5; one end of the resistor R6 is connected to the control end of the switching transistor Q1B, and the other end is grounded;

[0024] When a moving contact of the sliding switch is connected to the second stationary contact, the switching transistor Q1B is turned on, and electric energy in the capacitor C2 is discharged through the switching transistor Q1B to prepare for a quick start during the next power-on.

[0025] In this solution, the switching transistor Q1B is connected at the second stationary contact of the sliding switch. Through the triggering of the sliding switch shutdown signal, the discharge circuit of the capacitor C1 is turned on to prepare for a quick start during the next power-on.

[0026] In a further embodiment, the first switch module includes a switching transistor Q2, a resistor R7, a diode D1, and a capacitor C4. A first end of the switching transistor Q2 is connected to a rear-end load, a second end is connected to a battery pack, and a control end is connected to the second switch module and the third switch module; a positive electrode of the diode D1 is connected to the control end of the switching transistor Q2, and a negative electrode is connected to the second end of the switching transistor Q2; the resistor R7 is connected in parallel with the diode D1; one end of the capacitor C4 is connected to the control end of the switching transistor Q2, and the other end is grounded.

[0027] In this solution, the first switch module with a switching transistor as the core is connected in series in the main circuit. Since the switching transistor can complete the conversion between the on and off states in a short time, it helps to reduce the switching loss in the switching power supply.

[0028] In a further embodiment, the second switch module includes a switching transistor Q3, a resistor R8, a resistor R9, a resistor R10, a capacitor C5, and a diode D2; a first end of the switching transistor Q3 is connected to the control end of the first switch module, a second end is grounded through the resistor R9, and a control end is connected to the output end of the first switch module through the resistor R8; one end of the resistor R10 is connected to the control end of the switching transistor Q3, and the other end is grounded; the capacitor C5 is connected in parallel with the resistor R10; a positive electrode of the diode D2 is connected to the main controller, and a negative electrode is connected to the control end of the switching transistor Q3;

[0029] The main controller drives the switching transistor Q3 to be turned on or off by changing the signal input to the positive electrode of the diode D2, and then changes the potential of the control end of the first switch module to turn on or off the main power supply circuit.

[0030] In this solution, a switching transistor Q3 is connected to the control terminal of the switching transistor Q2 for switching control, which can control the output of a large current with a small current. Moreover, in the cut-off state, the triode hardly consumes current, thereby reducing the power consumption of the entire circuit.

[0031] In a further embodiment, the third switching module includes a switching transistor Q4, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a diode D3, and a diode D4;

[0032] The first terminal of the switching transistor Q4 is connected to the negative electrodes of the diode D3 and the diode D4, the second terminal is grounded, and the control terminal is connected to the output terminal of the first trigger module through the resistor R13;

[0033] The positive electrode of the diode D3 is connected to the control terminal of the first switching module through the resistor R11; the positive electrode of the diode D4 is connected to the main controller for feeding back the working state of the switching transistor Q4 to the main controller;

[0034] Both ends of the resistor R12 are respectively connected to the first terminal and the control terminal of the switching transistor Q4; one end of the resistor R14 is connected to the battery pack, and the other end is connected to the control terminal of the switching transistor Q4 through the resistor R13;

[0035] After the first trigger module accesses the battery pack power supply through the sliding switch, it outputs a start signal to control the switching transistor Q4 to conduct, thereby driving the first switching module to conduct the main power supply circuit; at the same time, the main controller receives the power-on signal through the positive electrode of the diode D4, and then controls the second switching module to replace the switching transistor Q4 to drive the first switching module to conduct the main power supply circuit.

[0036] This solution sets a third switching module in parallel with the second switching module, uses the switching transistor Q4 to achieve the fast start of the sliding switch, and then uses the switching transistor Q3 to achieve the continuous conduction control of the main power supply circuit. It is converted from hardware control to software control, and can continue to supply power to the system after the sliding switch is turned off, avoiding the situation of immediate power-off after the sliding switch in the traditional circuit, thereby reducing unnecessary circuit restarts and energy consumption. This design achieves lower power consumption through optimized power management.

[0037] In a further embodiment, the switching transistor Q2 is an N-channel MOS transistor or a P-channel MOS transistor.

[0038] In a further embodiment, the battery pack is a lithium battery or a lead-acid battery. Description of the Drawings

[0039] Figure 1 is a system framework diagram of a low-power on-off circuit for a power tool provided by an embodiment of the present invention;

[0040] Figure 2 It is the hardware circuit diagram of some modules provided by the embodiments of the present invention;

[0041] Figure 3 It is the hardware circuit diagram of some modules provided by the embodiments of the present invention;

[0042] Figure 4 It is the hardware circuit diagram of some modules provided by the embodiments of the present invention;

[0043] Among them: the first switch module 1, the second switch module 2, the third switch module 3, the slide switch SW1, the first trigger module 4, the second trigger module 5, the main controller 6, and the battery pack 7. Specific embodiments

[0044] The following specifically illustrates the implementation manners of the present invention in conjunction with the accompanying drawings. The given embodiments are only for illustrative purposes and should not be construed as limiting the present invention. The accompanying drawings are only for reference and illustration and do not constitute a limitation on the protection scope of the present invention patent, because many changes can be made to the present invention without departing from the spirit and scope of the present invention. <�

[0045] A low-power on-off circuit for an electric tool provided by an embodiment of the present invention, as Figures 1 to 4 shown. In this embodiment, it includes:

[0046] The first switch module 1 connected in series on the main power supply loop;

[0047] The second switch module 2 and the third switch module 3 connected to the control end of the first switch module 1;

[0048] The first trigger module 4 and the second trigger module 5 connected to the slide switch SW1;

[0049] The main controller 6 connected to the second switch module 2, the third switch module 3, and the second trigger module 5;

[0050] The main controller 6 collects the status feedback of the slide switch SW1 through the second trigger module 5, or collects the status change of the third switch module 3; and then drives the first switch module 1 to conduct or disconnect the main power supply loop by controlling the status change of the second switch module 2;

[0051] After the first trigger module 4 accesses the power supply of the battery pack 7 through the slide switch SW1, it outputs a start signal to control the third switch module 3 to drive the first switch module 1 to conduct the main power supply loop; and after a preset time period, it outputs a shutdown signal to control the third switch module 3 to stop working, and the first trigger module 4 enters the low-power standby state.

[0052] In this embodiment, see Figure 2, the sliding switch SW1 includes a first static contact NC, a second static contact ON, and a moving contact. One end of the moving contact is electrically connected to the battery pack 7, and the other end is connected to the first static contact NC or the second static contact ON; the first static contact NC is connected to the input end of the first trigger module 4, and the second static contact ON is connected to the input end of the second trigger module 5.

[0053] In this embodiment, the first trigger module 4 includes a NAND gate U1A, a NAND gate U1B, a resistor R1, a capacitor C1, and a capacitor C2; one end of the resistor R1 is connected to the first static contact NC of the sliding switch SW1, and the other end is connected to the input end of the NAND gate U1A; the input end of the NAND gate U1B is connected to the output end of the NAND gate U1A, and the output end (such as Figure 2 , Figure 4 the connection point a in) is connected to the control end of the third switch module 3; one end of the capacitor C1 is connected to the other end of the resistor R1, and the other end is grounded; one end of the capacitor C2 is connected to the ADD pin of the NAND gate U1A, and the other end is grounded;

[0054] When the moving contact of the sliding switch SW1 is connected to the first static contact NC, the battery pack 7 charges the capacitor C1 through the resistor R1. Since the voltage across the capacitor C1 does not change suddenly, a low level is input to the input end of the NAND gate U1A at this time. Then, the output end of the NAND gate U1A outputs a low level to the input end of the NAND gate U1B, and the output end of the NAND gate U1B outputs a low level to control the third switch module 3 to drive the first switch module 1 to conduct the main power supply circuit;

[0055] The main controller 6 collects the state change of the third switch module 3, and then controls the second switch module 2 to replace the third switch module 3 to drive the first switch module 1 to conduct the main power supply circuit;

[0056] When the capacitor C1 is fully charged, a high level is input to the input end of the NAND gate U1A. Then, the output end of the NAND gate U1A outputs a high level to the input end of the NAND gate U1B, and the output end of the NAND gate U1B outputs a high level to control the first switch module 1 to stop working and enter the low power consumption state.

[0057] This embodiment takes a double NAND gate (NAND gate U1A and NAND gate U1B) and a capacitor as the core. The double NAND gate is used to trigger the signal for power access, and at the same time, combined with the charge storage ability of the capacitor. When the moving contact of the sliding switch SW1 is connected to the first static contact NC, the double NAND gate is triggered for quick startup; furthermore, when the capacitor C1 is fully charged, the input signal of the double NAND gate is changed, thus completing a signal transformation for one startup; finally, if the user forgets to turn off the sliding switch SW1, since the static current of the double NAND gate is maintained at 4 uA, the power consumption of the battery pack 7 can be greatly reduced, and it can still be maintained for more than 6 months even after the power tool has low power, avoiding the risk of the battery pack 7 being scrapped.

[0058] In this embodiment, the second trigger module 5 includes a signal trigger module, and the signal trigger module includes a switching transistor Q1A, a resistor R2, a resistor R3, a resistor R4, and a capacitor C3; the first end of the switching transistor Q1A is connected to the power supply terminal through the resistor R2, the second end is grounded, and the control end is connected to the second static contact ON of the sliding switch SW1 through the resistor R3; one end of the capacitor C3 is connected to the second static contact ON of the sliding switch SW1, and the other end is grounded; one end of the resistor R4 is connected to the control end of the switching transistor Q1A, and the other end is connected; the first end of the switching transistor Q1A is also connected to the main controller 6;

[0059] When the moving contact of the sliding switch SW1 is connected to the second static contact ON, the switching transistor Q1A is turned on, and a shutdown signal is output to the main controller 6. The main controller 6 drives the first switch module 1 to disconnect the main power supply circuit through controlling the second switch module 2, performing physical shutdown and software shutdown.

[0060] In this embodiment, a signal trigger module with the switching transistor Q1A as the core is connected to the second static contact ON of the sliding switch SW1 to monitor in real time whether the sliding switch SW1 slides to the second static contact ON, realizing real-time and low-power monitoring of the shutdown signal.

[0061] In this embodiment, the second trigger module 5 further includes a discharge module, and the discharge module includes a switching transistor Q1B, a resistor R5, and a resistor R6; the first end of the switching transistor Q1B is connected to one end of the capacitor C2, the second end is grounded, and the control end is connected to the second static contact ON through the resistor R5; one end of the resistor R6 is connected to the control end of the switching transistor Q1B, and the other end is grounded;

[0062] When the moving contact of the sliding switch SW1 is connected to the second static contact ON, the switching transistor Q1B is turned on, and the electric energy in the capacitor C2 is discharged through the switching transistor Q1B to prepare for a quick startup for the next power-on.

[0063] Among them, the switching transistor Q1A is an N-channel MOS transistor or a P-channel MOS transistor; the switching transistor Q1B is an N-channel MOS transistor or a P-channel MOS transistor.

[0064] In this embodiment, the switching transistor Q1B is connected to the second static contact ON of the sliding switch SW1. By triggering the shutdown signal of the sliding switch SW1, the discharge circuit of the capacitor C1 is conducted to prepare for the quick start of the next startup.

[0065] Among them, the switching transistor Q1A and the switching transistor Q1B form a composite transistor.

[0066] In this embodiment, referring to Figure 3 , the first switching module 1 includes a switching transistor Q2, a resistor R7, a diode D1, and a capacitor C4. The first end of the switching transistor Q2 is connected to the connection point c of the rear-end load (such as Figure 3 ), the second end is connected to the battery pack 7, and the control end is connected to the second switching module 2 and the third switching module 3; the positive electrode of the diode D1 is connected to the control end of the switching transistor Q2, and the negative electrode is connected to the second end of the switching transistor Q2; the resistor R7 is connected in parallel with the diode D1; one end of the capacitor C4 is connected to the control end of the switching transistor Q2, and the other end is grounded.

[0067] In this embodiment, the switching transistor Q2 is an N-channel MOS transistor or a P-channel MOS transistor.

[0068] In this embodiment, the first switching module 1 with a switching transistor as the core is connected in series in the main circuit. Since the switching transistor can complete the conversion between the on and off states in a short time, it helps to reduce the switching loss in the switching power supply.

[0069] In this embodiment, the second switching module 2 includes a switching transistor Q3, a resistor R8, a resistor R9, a resistor R10, a capacitor C5, and a diode D2; the first end of the switching transistor Q3 is connected to the control end of the first switching module 1, the second end is grounded through the resistor R9, and the control end is connected to the output end of the first switching module 1 through the resistor R8; one end of the resistor R10 is connected to the control end of the switching transistor Q3, and the other end is grounded; the capacitor C5 is connected in parallel with the resistor R10; the positive electrode of the diode D2 is connected to the main controller 6, and the negative electrode is connected to the control end of the switching transistor Q3;

[0070] The main controller 6 drives the switching transistor Q3 to conduct or cut off by changing the signal input to the positive electrode of the diode D2, thereby changing the potential of the control end of the first switching module 1 and conducting or turning off the main power supply circuit.

[0071] In this embodiment, the switching transistor Q3 is an NPN-type triode or a PNP-type triode.

[0072] In this embodiment, a switching transistor Q3 is connected to the control terminal of the switching transistor Q2 for switching control, which can control the output of a large current with a small current. Moreover, in the cut-off state, the triode hardly consumes current, thereby reducing the power consumption of the entire circuit.

[0073] In this embodiment, refer to Figure 4 , the third switching module 3 includes a switching transistor Q4, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a diode D3 and a diode D4;

[0074] The first terminal of the switching transistor Q4 is connected to the negative electrodes of the diode D3 and the diode D4, the second terminal is grounded, and the control terminal is connected to the output terminal of the first trigger module 4 through the resistor R13;

[0075] The positive electrode of the diode D3 is connected to the control terminal of the first switching module 1 (such as Figure 3 , Figure 4 the connection point b in) through the resistor R11; the positive electrode of the diode D4 is connected to the main controller 6 for feeding back the operating state of the switching transistor Q4 to the main controller 6;

[0076] Both ends of the resistor R12 are respectively connected to the first terminal and the control terminal of the switching transistor Q4; one end of the resistor R14 is connected to the battery pack 7, and the other end is connected to the control terminal of the switching transistor Q4 through the resistor R13;

[0077] After the first trigger module 4 accesses the power supply of the battery pack 7 through the slide switch SW1, it outputs a start signal to control the switching transistor Q4 to conduct, and then drives the first switching module 1 to conduct the main power supply circuit; at the same time, the main controller 6 receives the power-on signal through the positive electrode of the diode D4, and then controls the second switching module 2 to replace the switching transistor Q4 to drive the first switching module 1 to conduct the main power supply circuit.

[0078] Among them, the diodes D3 and D4 are used for anti-backflow to ensure the accuracy of signal triggering.

[0079] In this embodiment, the switching transistor Q4 is an NPN type triode or a PNP type triode.

[0080] This embodiment sets a third switching module 3 in parallel with the second switching module 2. The switching transistor Q4 is used to achieve the quick start of the slide switch SW1, and then the switching transistor Q3 is used to achieve the continuous conduction control of the main power supply circuit, which is converted from hardware control to software control. It can continue to supply power to the system after the slide switch SW1 is turned off, avoiding the situation of immediate power-off after the slide switch SW1 in the traditional circuit, thereby reducing unnecessary circuit restarts and energy consumption. This design realizes lower power consumption through optimized power management.

[0081] In this embodiment, the battery pack 7 is a lithium battery or a lead-acid battery.

[0082] The main controller 6 is a chip with data processing functions, including but not limited to an MCU.

[0083] See Figure 2 , taking the switching transistor Q1A as an N-channel MOS transistor, the switching transistor Q1B as an N-channel MOS transistor, the switching transistor Q2 as a P-channel MOS transistor, the switching transistor Q3 as an NPN-type triode, and the switching transistor Q4 as a PNP-type triode as examples, the power-on and power-off principle of this embodiment is as follows:

[0084] I. Power-on startup

[0085] (1) When the moving contact of the slide switch SW1 is connected to the first stationary contact NC, the battery pack 7 charges the capacitor C1 through the resistor R1. Since the voltage across the capacitor C1 does not change suddenly, at this time, a low level is input to the input terminal of the NAND gate U1A, so the output terminal of the NAND gate U1A outputs a low level to the input terminal of the NAND gate U1B, and the output terminal of the NAND gate U1B outputs a low level. At this time, the switching transistors Q4 and Q2 are turned on in sequence, and the main controller 6 detects the power-on signal through SW-DE1; the main controller 6 outputs a high level to maintain PW_CL, causing the switching transistor Q3 to turn on, and the switching transistor Q3 maintains the conduction control of the switching transistor Q2.

[0086] A power-on startup is completed.

[0087] (2) If the moving contact of the slide switch SW1 continues to be connected to the first stationary contact NC, when the capacitor C1 is fully charged, a high level is input to the input terminal of the NAND gate U1A, so the output terminal of the NAND gate U1A outputs a high level to the input terminal of the NAND gate U1B, and the output terminal of the NAND gate U1B outputs a high level to control the switching transistor Q4 to stop working and enter the low-power state.

[0088] In the powered-on state, after the power tool runs out of power and shuts down software, if the user forgets to slide the slide switch SW1 to the POWER-OFF state (that is, the moving contact of the slide switch SW1 continues to be connected to the first stationary contact NC), because the switching transistor Q4 has already been turned off after the capacitor C1 is fully charged, the standby current of the double NAND gate is maintained at about 4 μA (the power supply of the double NAND gate is 3V~18V. When the voltage of the battery pack 7 is lower than 3V, the double NAND gate stops working and waits to work again after being recharged to avoid the battery pack 7 from running out of power), and the current of Q5 and the peripheral circuit is also maintained at a few μA. The total current is within about 15 μA. In this way, after the power tool runs out of power, it can be maintained for more than 6 months, thus avoiding the risk of the battery pack 7 being scrapped.

[0089] II. Shutdown control

[0090] When the moving contact of the sliding switch SW1 is connected to the second static contact ON, the switch tube Q1A is turned on, and a shutdown signal is output to the main controller 6 through the port SW-DE2. The main controller 6 outputs a low level through PW_CL, so that the switch tube Q3 is turned off, the switch tube Q2 is turned off, the main power supply circuit is disconnected, and physical shutdown and software shutdown are performed.

[0091] In the embodiment of the present invention, a first trigger module 4 is connected in series between the sliding switch SW1 and the third switch module 3, and the hardware startup and software startup are controlled in sequence to achieve rapid startup while ensuring the normal operation of the circuit; and by outputting a shutdown signal to control the third switch module 3 to stop working after a preset time period, even if the startup circuit corresponding to the first switch module 1 is connected to the battery through the sliding switch SW1 after power is turned on, it can be stopped by the third switch module 3, so that the power-on loop of the startup circuit only requires an extremely low quiescent current, thereby greatly reducing the startup energy consumption of the circuit, effectively improving the battery life of the battery pack 7, and avoiding the risk of the battery pack 7 being scrapped due to forgetting to turn off the sliding switch SW1.

[0092] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A low-power on-off circuit for a power tool, characterized in that, Including: A first switch module connected in series on the main power supply loop; A second switch module and a third switch module connected to the control end of the first switch module; A first trigger module and a second trigger module connected to the sliding switch; A main controller connected to the second switch module, the third switch module, and the second trigger module; The main controller collects the status feedback of the sliding switch through the second trigger module, or collects the status change of the third switch module; and then drives the first switch module to conduct or disconnect the main power supply loop by controlling the status change of the second switch module; After the battery pack power supply is connected through the sliding switch, the first trigger module outputs a start signal to control the third switch module to drive the first switch module to conduct the main power supply loop; and after a preset time period, outputs a shutdown signal to control the third switch module to stop working, and the first trigger module enters the low-power standby state; The first trigger module includes a NAND gate U1A, a NAND gate U1B, a resistor R1, a capacitor C1, and a capacitor C2; one end of the resistor R1 is connected to the first static contact of the sliding switch, and the other end is connected to the input end of the NAND gate U1A; the input end of the NAND gate U1B is connected to the output end of the NAND gate U1A, and the output end is connected to the control end of the third switch module; one end of the capacitor C1 is connected to the other end of the resistor R1, and the other end is grounded; one end of the capacitor C2 is connected to the ADD pin of the NAND gate U1A, and the other end is grounded; When the moving contact of the sliding switch is connected to the first static contact, the battery pack charges the capacitor C1 through the resistor R1. Since the voltage across the capacitor C1 does not change suddenly, at this time, a low level is input to the input end of the NAND gate U1A, and the output end of the NAND gate U1A outputs a low level to the input end of the NAND gate U1B. The output end of the NAND gate U1B outputs a low level to control the third switch module to drive the first switch module to conduct the main power supply loop; The main controller collects the status change of the third switch module, and then drives the first switch module to conduct the main power supply loop by controlling the second switch module to replace the third switch module; When the capacitor C1 is fully charged, a high level is input to the input end of the NAND gate U1A, and the output end of the NAND gate U1A outputs a high level to the input end of the NAND gate U1B. The output end of the NAND gate U1B outputs a high level to control the first switch module to stop working and enter the low-power state.

2. The low-power on-off circuit for a power tool according to claim 1, wherein: The sliding switch includes a first static contact, a second static contact, and a moving contact. One end of the moving contact is electrically connected to the battery pack, and the other end is connected to the first static contact or the second static contact; the first static contact is connected to the input end of the first trigger module, and the second static contact is connected to the input end of the second trigger module.

3. The low-power on-off circuit for a power tool according to claim 2, wherein: The second trigger module includes a signal trigger module, and the signal trigger module includes a switching transistor Q1A, a resistor R2, a resistor R3, a resistor R4, and a capacitor C3. The first end of the switching transistor Q1A is connected to the power supply terminal through the resistor R2, the second end is grounded, and the control end is connected to the second stationary contact of the sliding switch through the resistor R3. One end of the capacitor C3 is connected to the second stationary contact of the sliding switch, and the other end is grounded. One end of the resistor R4 is connected to the control end of the switching transistor Q1A, and the other end is connected. The first end of the switching transistor Q1A is also connected to the main controller. When the moving contact of the sliding switch is connected to the second stationary contact, the switching transistor Q1A is turned on, and a shutdown signal is output to the main controller. The main controller drives the first switch module to disconnect the main power supply circuit through controlling the second switch module, performing physical shutdown and software shutdown.

4. The low-power on-off circuit for a power tool according to claim 3, wherein: The second trigger module further includes a discharge module, and the discharge module includes a switching transistor Q1B, a resistor R5, and a resistor R6. The first end of the switching transistor Q1B is connected to one end of the capacitor C2, the second end is grounded, and the control end is connected to the second stationary contact through the resistor R5. One end of the resistor R6 is connected to the control end of the switching transistor Q1B, and the other end is grounded. When the moving contact of the sliding switch is connected to the second stationary contact, the switching transistor Q1B is turned on, and the electric energy in the capacitor C2 is discharged through the switching transistor Q1B to prepare for a quick start of the next power-on.

5. The low-power on-off circuit for a power tool according to claim 1, wherein: The first switch module includes a switching transistor Q2, a resistor R7, a diode D1, and a capacitor C4. The first end of the switching transistor Q2 is connected to the rear-end load, the second end is connected to the battery pack, and the control end is connected to the second switch module and the third switch module. The positive pole of the diode D1 is connected to the control end of the switching transistor Q2, and the negative pole is connected to the second end of the switching transistor Q2. The resistor R7 is connected in parallel with the diode D1. One end of the capacitor C4 is connected to the control end of the switching transistor Q2, and the other end is grounded.

6. The low-power on-off circuit for a power tool according to claim 1, characterized in that: The second switch module includes a switching transistor Q3, a resistor R8, a resistor R9, a resistor R10, a capacitor C5, and a diode D2. The first end of the switching transistor Q3 is connected to the control end of the first switch module, the second end is grounded through the resistor R9, and the control end is connected to the output end of the first switch module through the resistor R8. One end of the resistor R10 is connected to the control end of the switching transistor Q3, and the other end is grounded. The capacitor C5 is connected in parallel with the resistor R10. The positive pole of the diode D2 is connected to the main controller, and the negative pole is connected to the control end of the switching transistor Q3. The main controller drives the switching transistor Q3 to be turned on or off by changing the signal input to the positive pole of the diode D2, and further changes the potential of the control end of the first switch module to turn on or off the main power supply circuit.

7. The low-power on-off circuit for a power tool according to claim 3, wherein: The third switch module includes a switching transistor Q4, a resistor R11, a resistor R12, a resistor R13, a resistor R14, a diode D3, and a diode D4. The first end of the switching transistor Q4 is connected to the negative pole of the diode D3 and the negative pole of the diode D4, the second end is grounded, and the control end is connected to the output end of the first trigger module through the resistor R13. The positive electrode of diode D3 is connected to the control terminal of the first switching module through resistor R11; the positive electrode of diode D4 is connected to the main controller, and is used to feedback the working state of switching transistor Q4 to the main controller. Both ends of resistor R12 are respectively connected to the first end and the control terminal of switching transistor Q4; one end of resistor R14 is connected to the battery pack, and the other end is connected to the control terminal of switching transistor Q4 through resistor R13. After the first triggering module accesses the battery pack power supply through the sliding switch, it outputs a start signal to control switching transistor Q4 to conduct, and then drives the first switching module to conduct the main power supply circuit; at the same time, the main controller receives the power-on signal through the positive electrode of diode D4, and then controls the second switching module to replace switching transistor Q4 to drive the first switching module to conduct the main power supply circuit.

8. The low-power on-off circuit for a power tool according to claim 5, characterized in that: The switching transistor Q2 is an N-channel MOS transistor or a P-channel MOS transistor.

9. A low-power on-off circuit for a power tool according to any one of claims 1 to 8, characterized in that: The battery pack is a lithium battery or a lead-acid battery.

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