A start-stop automatic controller

Abstract

The present application belongs to the field of automatic control of liquid pump, and relates to a start-stop automatic controller, comprising: a voltage reduction circuit, a pulse signal acquisition circuit, a single-chip microcomputer and a relay output circuit connected electrically; the voltage reduction circuit comprises an AC / DC voltage reduction circuit and a DC / DC voltage reduction circuit; an input end of the AC / DC voltage reduction circuit is connected with an AC power input terminal, and an output end of the AC / DC voltage reduction circuit is connected with an input end of the DC / DC voltage reduction circuit; an output end of the DC / DC voltage reduction circuit is connected with a power supply pin of the single-chip microcomputer; an input end of the pulse signal acquisition circuit is connected with a signal output end of a turbine inductive sensor; the relay output circuit comprises a relay and a relay drive circuit. The start-stop automatic controller can adapt to the conditions of not full pipe and air inlet, has an all-electronic structure, no mechanical fatigue problem, wide voltage input, good power supply adaptability, high control precision, is suitable for all liquid pumps, can protect the pump body, reduce energy consumption and noise, has a clear circuit structure and is easy to realize.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for liquid pumps, and more specifically, to an automatic start-stop controller. Background Technology

[0002] In liquid delivery systems, the start-stop control of the liquid pump is a crucial aspect. Traditional control methods primarily employ pressure switch control, which works by detecting pressure changes within the pipeline to regulate pump operation. When the pipeline pressure falls below a set value, the pressure switch closes, and the pump starts; when the pressure reaches the set value, the pressure switch opens, and the pump stops.

[0003] However, this traditional pressure switch control method has the following drawbacks:

[0004] First, a pressure switch must be used in conjunction with a check valve to achieve pressure sealing. The function of the check valve is to prevent liquid backflow after the pump stops and to maintain the pressure in the pipeline. However, in actual use, check valves are prone to air or water leakage due to impurities in the liquid, aging of the sealing ring, etc., which can cause the pressure to be lost, thus rendering the pressure switch unable to make accurate judgments.

[0005] Second, when the pipe is not full of liquid, meaning there is a mixture of gas and liquid flowing within the pipe, the pressure switch cannot function properly. Because gas is compressible, the pressure fluctuations in a partially filled pipe are completely different from those in a fully filled pipe, making it difficult for the pressure switch to accurately detect the actual water pressure changes.

[0006] Third, when air enters the pipeline, the presence of air will make the pressure signal unstable, and the pressure switch is prone to malfunction, causing the pump to start and stop frequently or run dry when there is no liquid.

[0007] Fourth, traditional pressure switches use mechanical and spring structures. Over long-term use, springs can experience fatigue and changes in their elastic coefficient, causing the pressure switch's actuation threshold to drift and reducing control accuracy. As usage time increases, spring fatigue becomes more severe, ultimately resulting in a high product failure rate and short lifespan. Summary of the Invention

[0008] To address the aforementioned deficiencies in the prior art, the present invention provides an automatic start-stop controller, comprising:

[0009] The circuit consists of a step-down circuit, a pulse signal acquisition circuit, a microcontroller, and a relay output circuit, all electrically connected.

[0010] The step-down circuit includes an AC / DC step-down circuit and a DC / DC step-down circuit;

[0011] The input terminal of the AC / DC step-down circuit is connected to the AC power input terminal, and the output terminal of the AC / DC step-down circuit is connected to the input terminal of the DC / DC step-down circuit.

[0012] The output terminal of the DC / DC step-down circuit is connected to the power supply pin of the microcontroller;

[0013] The input terminal of the pulse signal acquisition circuit is connected to the signal output terminal of the turbine induction sensor, and the output terminal of the pulse signal acquisition circuit is connected to the pulse input pin of the microcontroller.

[0014] The relay output circuit includes a relay and a relay driving circuit. The input terminal of the relay driving circuit is connected to the control pin of the microcontroller, and the output terminal of the relay driving circuit is connected to both ends of the relay coil. The contact switch of the relay is connected in series in the power supply circuit of the external liquid pump motor.

[0015] Preferably, the AC / DC step-down circuit includes a first step-down chip, a first inductor, a first capacitor, a second capacitor, a first diode, a second diode, and a first resistor;

[0016] The DRAIN pin of the first step-down chip is connected to the high voltage input terminal of the rectified AC power supply. The VCC pin of the first step-down chip is grounded through the first capacitor. The SEL pin of the first step-down chip is grounded through the first resistor. The SOURCE pin of the first step-down chip is grounded.

[0017] The DRAIN pin of the first step-down chip is also connected to the cathode of the first diode, the anode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is grounded;

[0018] A first inductor is connected between the SOURCE pin and the DRAIN pin of the first step-down chip;

[0019] The connection point between the first inductor and the cathode of the first diode serves as the output terminal of the AC / DC step-down circuit, and this output terminal is grounded through the second capacitor.

[0020] Preferably, the SEL pin of the first step-down chip is grounded through a first resistor, so that the output voltage is locked at 12V;

[0021] The first step-down chip integrates a 500V high-voltage MOSFET and adopts a non-isolated step-down AC-DC constant voltage topology.

[0022] Preferably, the DC / DC step-down circuit includes a second step-down chip, a second inductor, a third capacitor, a fourth capacitor, a second resistor, and a third resistor;

[0023] The VIN pin of the second step-down chip is connected to the output terminal of the AC / DC step-down circuit and grounded through the third capacitor;

[0024] The SW pin of the second step-down chip is connected to one end of the second inductor, and the other end of the second inductor serves as the output terminal of the DC / DC step-down circuit. This output terminal is grounded through the fourth capacitor.

[0025] The FB pin of the second step-down chip is connected to the output terminal of the DC / DC step-down circuit through a second resistor, and is also grounded through a third resistor;

[0026] The GND pin of the second buck converter is grounded, and the EN pin of the second buck converter is connected to its VIN pin.

[0027] Preferably, the second buck chip integrates a high-side MOSFET and a low-side MOSFET, adopts a synchronous rectification buck topology, and has a switching frequency of 1MHz;

[0028] The internal reference voltage of the FB pin of the second step-down chip is 0.6V, and the output voltage is set by the ratio of the second resistor to the third resistor.

[0029] Preferably, the pulse signal acquisition circuit includes a fourth resistor, a fifth resistor, a fifth capacitor, and a transistor;

[0030] The signal output terminal of the turbine sensor is connected to the base of the transistor through a fourth resistor. The base of the transistor is grounded through a fifth resistor, and the base of the transistor is also grounded through a fifth capacitor.

[0031] The emitter of the transistor is grounded, the collector of the transistor is connected to the pulse input pin of the microcontroller, and the collector of the transistor is connected to the output terminal of the DC / DC buck circuit through a pull-up resistor.

[0032] Preferably, the relay driving circuit includes a sixth resistor, a seventh resistor, a sixth capacitor, and an N-channel MOSFET;

[0033] The control pin of the microcontroller is connected to the gate of the N-channel MOSFET through the sixth resistor. The gate of the N-channel MOSFET is grounded through the seventh resistor. The gate of the N-channel MOSFET is also grounded through the sixth capacitor.

[0034] The source of the N-channel MOSFET is grounded, and the drain of the N-channel MOSFET is connected to one end of the relay coil. The other end of the relay coil is connected to the output of the DC / DC step-down circuit.

[0035] A freewheeling diode is connected in parallel across the coil of the relay. The cathode of the freewheeling diode is connected to the output terminal of the DC / DC step-down circuit, and the anode is connected to the drain of the N-channel MOSFET.

[0036] Preferably, the turbine sensing sensor is a water flow turbine sensor, which has an impeller and a magnet inside. The impeller rotates under the drive of liquid flow, and the magnet generates a pulse signal when it is close to a Hall element or a reed switch.

[0037] Preferably, the microcontroller integrates a pulse counting module and a timer module. The pulse counting module is used to receive the number of pulses output by the pulse signal acquisition circuit, and the timer module is used to set the pulse sampling time window.

[0038] The microcontroller calculates the instantaneous flow rate value based on the number of pulses per unit time according to a preset flow rate-pulse ratio, compares it with preset start flow rate thresholds and stop flow rate thresholds, and outputs start / stop control signals.

[0039] Preferably, the AC power input terminal is connected to an AC 85V~265V wide voltage input power supply;

[0040] The AC / DC step-down circuit outputs 12V DC power, and the DC / DC step-down circuit outputs 5V DC power.

[0041] The microcontroller operates at 5V, and the relay operates at 12V.

[0042] The automatic start-stop controller of the present invention has the following advantages:

[0043] (1) No check valve required: The flow state of the liquid in the pipeline is directly detected by the turbine induction principle, rather than the pressure. Therefore, there is no need to use a check valve. Even if the check valve leaks air or water, it will not affect the normal operation of the controller, greatly reducing the dependence on pipeline accessories.

[0044] (2) Adaptable to incomplete pipe and air ingress conditions: When the pipe is not full of liquid or air enters, as long as there is still liquid flowing in the pipe, the turbine will rotate and generate a pulse signal, and the controller can work normally. The presence of air will not substantially interfere with the pulse signal, overcoming the defect that the pressure switch cannot work normally under such conditions.

[0045] (3) All-electronic structure, no mechanical fatigue problem: The mechanical structure such as springs is completely eliminated, and electronic induction and microcontroller control are adopted. The step-down circuit, pulse acquisition circuit and relay drive circuit are all solid-state electronic circuits, which do not have problems such as mechanical fatigue and elastic coefficient change. The long-term performance is stable and the failure rate is greatly reduced.

[0046] (4) Wide voltage input and good power supply adaptability: The AC / DC step-down circuit uses the BP2522F chip, which supports a wide range of AC input from 85V to 265V, and can adapt to the mains power standards of different countries and regions around the world. The DC / DC step-down circuit further stabilizes the output of 5V, ensuring the reliable operation of the microcontroller.

[0047] (5) High control precision: The microcontroller calculates flow rate through pulse counting and timers, which can accurately determine the start and stop of liquid flow. Compared with the fuzzy threshold of mechanical pressure switches, digital flow rate determination has higher precision and consistency.

[0048] (6) Applicable to all liquid pumps: It can be installed on the pipeline of any liquid pump and is controlled by sensing the liquid flow, without being limited by factors such as pump type, head, or power. At the same time, since it uses flow sensing instead of pressure sensing, it is not affected by pressure differences caused by the distance of the pipeline, and has a wider range of applications.

[0049] (7) It can protect the pump body and reduce energy consumption and noise: When the liquid stops flowing, the controller outputs a stop signal in time to stop the pump from running, avoiding wear and overheating caused by the pump running dry for a long time, and eliminating the noise generated by the pump running dry, thus saving energy.

[0050] (8) The circuit structure is clear and easy to implement: The circuit of this invention adopts mature step-down chips and standard transistor and MOSFET driving circuits. It has fewer components, lower cost, and higher reliability, making it suitable for mass production and widespread application. Attached Figure Description

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort. The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0052] Figure 1 This is a schematic diagram of the constituent modules of the automatic start / stop controller of the present invention;

[0053] Figure 2 This is a circuit diagram of the AC / DC step-down circuit of the automatic start / stop controller of the present invention;

[0054] Figure 3 This is a circuit diagram of the DC / DC step-down circuit of the automatic start / stop controller of this invention;

[0055] Figure 4 This is an exploded view of a preferred embodiment of the automatic start / stop controller of the present invention;

[0056] Figure 5 This is a perspective view of a preferred embodiment of the automatic start / stop controller of the present invention;

[0057] Figure 6 This is a top view of a preferred embodiment of the automatic start / stop controller of the present invention;

[0058] Figure 7 This is a left view of a preferred embodiment of the automatic start / stop controller of the present invention;

[0059] Figure 8 This is a bottom view of a preferred embodiment of the automatic start / stop controller of the present invention;

[0060] Figure 9 This is a right view of a preferred embodiment of the automatic start / stop controller of the present invention;

[0061] Figure 10 This is a front view of a preferred embodiment of the automatic start / stop controller of the present invention. Detailed Implementation

[0062] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0063] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0064] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. If the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0065] Please see Figure 1 This is a schematic diagram of the constituent modules of the automatic start / stop controller of the present invention. Figure 1 As shown, the start-stop automatic controller provided in the first embodiment of the present invention includes components electrically connected to:

[0066] AC power input terminals (L, N) (not shown in the diagram) are connected to an 85V~265V AC power supply.

[0067] The rectifier and filter circuit (not shown in the diagram, including the rectifier bridge and filter capacitor) converts alternating current into pulsating direct current.

[0068] The step-down circuit includes an AC / DC step-down circuit and a DC / DC step-down circuit. The AC / DC step-down circuit uses the BP2522F chip to step down the high voltage DC to 12V DC.

[0069] The DC / DC step-down circuit uses the ME3121AM6G chip to step down 12V DC to 5V DC.

[0070] The turbine sensing sensor (installed inside the pipe, not shown in the diagram) outputs a pulse signal.

[0071] The pulse signal acquisition circuit shapes and converts the pulse signal level.

[0072] Microcontrollers (such as STC15W series or STM8 series) run control algorithms;

[0073] The relay output circuit drives the relay coil and controls the power supply to the pump.

[0074] The input terminal of the AC / DC step-down circuit is connected to the AC power input terminal, and the output terminal of the AC / DC step-down circuit is connected to the input terminal of the DC / DC step-down circuit. The output terminal of the DC / DC step-down circuit is connected to the power pin of the microcontroller. The input terminal of the pulse signal acquisition circuit is connected to the signal output terminal of the turbine sensor, and the output terminal of the pulse signal acquisition circuit is connected to the pulse input pin of the microcontroller. The relay output circuit includes a relay and a relay drive circuit. The input terminal of the relay drive circuit is connected to the control pin of the microcontroller, and the output terminal of the relay drive circuit is connected to both ends of the relay coil. The relay contact switch is connected in series in the power supply circuit of the external liquid pump motor.

[0075] In practice, the AC power input terminal is connected in sequence to the DRAIN pin of the rectifier filter circuit and the AC / DC step-down circuit; the output terminal (12V) of the AC / DC step-down circuit is connected to the VIN pin of the DC / DC step-down circuit, which also provides power to the relay coil; the output terminal (5V) of the DC / DC step-down circuit is connected in sequence to the VCC pin of the microcontroller, the pull-up resistor of the pulse signal acquisition circuit, and the logic part of the relay drive circuit; the signal output terminal of the turbine sensor is connected to the input terminal of the pulse signal acquisition circuit; the output terminal of the pulse signal acquisition circuit is connected to the pulse input pin (e.g., P3.2 / INT0) of the microcontroller; and the control pin (e.g., P1.0) of the microcontroller is connected to the input terminal of the relay drive circuit.

[0076] The AC / DC step-down circuit includes a first step-down chip, a first inductor, a first capacitor, a second capacitor, a first diode, a second diode, and a first resistor;

[0077] The DRAIN pin of the first step-down chip is connected to the high voltage input terminal of the rectified AC power supply. The VCC pin of the first step-down chip is grounded through the first capacitor. The SEL pin of the first step-down chip is grounded through the first resistor. The SOURCE pin of the first step-down chip is grounded.

[0078] The DRAIN pin of the first step-down chip is also connected to the cathode of the first diode, the anode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is grounded.

[0079] The first inductor is connected between the SOURCE pin and the DRAIN pin of the first step-down chip.

[0080] The connection point between the first inductor and the cathode of the first diode serves as the output terminal of the AC / DC step-down circuit, and this output terminal is grounded through the second capacitor.

[0081] The SEL pin of the first step-down chip is grounded through the first resistor, so that the output voltage is locked at 12V;

[0082] The first step-down chip integrates a 500V high-voltage MOSFET and adopts a non-isolated step-down AC-DC constant voltage topology.

[0083] Figure 2 This is a circuit diagram of the AC / DC step-down circuit of the automatic start / stop controller of this invention. Figure 2 As shown, in specific implementation, the first step-down chip is selected as BP2522F.

[0084] Let the positive terminal of the high voltage DC obtained after the AC input is rectified and filtered be HV+, and the negative terminal be GND_HV (this GND is not isolated from the subsequent low voltage GND, but a safe distance is ensured through PCB layout).

[0085] The DRAIN pin of the first step-down chip U1 (BP2522F) is directly connected to HV+;

[0086] The VCC pin of the first step-down chip U1 is connected to GND_HV through the first capacitor C1 (typical value 10μF / 50V);

[0087] The SEL pin of the first step-down chip U1 is connected to GND_HV through the first resistor R1 (typical value 10kΩ);

[0088] The SOURCE pin of the first step-down chip U1 is directly connected to GND_HV;

[0089] The cathode of the first diode D1 is connected to the DRAIN pin of the first step-down chip U1, the anode of the first diode D1 is connected to the cathode of the second diode D2, and the anode of the second diode D2 is connected to GND_HV.

[0090] The first inductor L1 (typical value 1mH) is connected between the SOURCE pin of the first step-down chip U1 and the cathode of the first diode D1;

[0091] The positive terminal of the second capacitor C2 (typical value 470μF / 25V) is connected to the cathode of the first diode D1 (i.e. the 12V output terminal), and the negative terminal is connected to GND_HV;

[0092] The 12V output terminal is marked as VCC12V.

[0093] The working principle of the AC / DC step-down circuit is:

[0094] The BP2522F is a non-isolated step-down AC-DC constant voltage chip that integrates a 500V high-voltage MOSFET and a PWM controller.

[0095] Upon power-up, high-voltage DC current enters the chip's internal high-voltage startup circuit through the DRAIN pin, which charges the C1 capacitor connected to the VCC pin. When the VCC voltage rises to the chip's startup threshold (typically 12V), the chip's internal circuitry begins to operate.

[0096] The BP2522F chip's internal MOSFET switches at a high frequency (typically 60kHz~100kHz). When the internal MOSFET is on, current flows from HV+ through DRAIN → internal MOSFET → SOURCE → L1 → load (subsequent circuit) → GND_HV, forming a loop. The first inductor L1 stores energy. When the internal MOSFET is off, the current in the first inductor L1 cannot change abruptly. It continues to flow through the loop formed by the freewheeling diodes D1 and D2, maintaining the output current. At the same time, the voltage across the first inductor L1 reverses, keeping the output voltage at the set value.

[0097] The SEL pin is grounded via R1, selecting an output voltage of 12V. Internally, the chip compares the sampled output voltage (via an internal feedback pin, eliminating the need for an external optocoupler) with an internal reference to adjust the PWM duty cycle, stabilizing the output voltage at 12V ± 5%.

[0098] The AC / DC step-down circuit is characterized by its ability to obtain low-voltage DC directly from the voltage after high-voltage AC rectification, eliminating the need for a power frequency transformer. It is also characterized by its small size, high efficiency, and low standby power consumption.

[0099] The DC / DC step-down circuit includes a second step-down chip, a second inductor, a third capacitor, a fourth capacitor, a second resistor, and a third resistor;

[0100] The VIN pin of the second step-down chip is connected to the output of the AC / DC step-down circuit and grounded through the third capacitor;

[0101] The SW pin of the second step-down chip is connected to one end of the second inductor, and the other end of the second inductor serves as the output terminal of the DC / DC step-down circuit. This output terminal is grounded through the fourth capacitor.

[0102] The FB pin of the second step-down chip is connected to the output of the DC / DC step-down circuit through the second resistor, and is also grounded through the third resistor;

[0103] The GND pin of the second buck converter is grounded, and the EN pin of the second buck converter is connected to its VIN pin.

[0104] The second buck chip integrates a high-side MOSFET and a low-side MOSFET, adopts a synchronous rectification buck topology, and has a switching frequency of 1MHz.

[0105] The internal reference voltage of the FB pin of the second step-down chip is 0.6V, and the output voltage is set by the ratio of the second resistor to the third resistor.

[0106] Figure 3 This is a circuit diagram of the DC / DC step-down circuit of the automatic start / stop controller of this invention. Figure 3 As shown, in specific implementation, the second step-down chip is selected as ME3121AM6G.

[0107] The VIN pin of the second step-down chip U2 (ME3121AM6G) is connected to the AC DC output VCC12V, and is grounded through the third capacitor C3 (typical value 10μF / 16V);

[0108] The EN pin of the second step-down chip U2 is directly connected to the VIN pin;

[0109] The SW pin of the second step-down chip U2 is connected to one end of the second inductor L2 (typical value 4.7μH);

[0110] The other end of L2 serves as a 5V output terminal (VCC5V) and is grounded through the fourth capacitor C4 (typical value 22μF / 6.3V);

[0111] The FB pin of U2 is connected to VCC5V through a second resistor R2 (typically 100kΩ), and grounded through a third resistor R3 (typically 20kΩ).

[0112] The GND pin of the second step-down chip U2 is directly grounded.

[0113] The working principle of a DC / DC step-down circuit is:

[0114] The ME3121AM6G is a synchronous rectified buck DC-DC converter that integrates high-side and low-side power MOSFETs and employs an adaptive constant on-time control architecture (ACOT).

[0115] When the chip is operating, the internal high-side MOSFET is turned on, and current flows from VIN through the high-side MOSFET → SW pin → L2 → load → GND. L2 stores energy, and the output capacitor C4 is charged simultaneously. Subsequently, the high-side MOSFET is turned off, and the internal low-side MOSFET is turned on. The current in L2 freewheels through the low-side MOSFET, continuing to supply power to the load.

[0116] The FB pin samples the output voltage through a voltage divider network composed of R2 and R3. The internal reference voltage of the ME3121AM6G chip is 0.6V. The error amplifier compares the FB pin voltage with 0.6V and dynamically adjusts the on-time of the high-side MOSFET to ensure that the output voltage satisfies Vout = 0.6 × (1 + R2 / R3). In this embodiment, R2 is 100kΩ and R3 is 20kΩ, so Vout = 0.6 × (1 + 100 / 20) = 0.6 × 6 = 3.6V. It should be noted that this is only an example; to achieve a 5V output, the resistor values ​​need to be adjusted. For example, if R3 = 10kΩ, then R2 needs to satisfy 0.6 × (1 + R2 / 10) = 5 → 1 + R2 / 10 = 8.33 → R2 / 10 = 7.33 → R2 = 73.3kΩ, so R2 can be 75kΩ.

[0117] The ME3121AM6G chip automatically enters PFM mode under light load to reduce the switching frequency and minimize switching losses; under heavy load, it switches to PWM mode to ensure load capacity. With a switching frequency of approximately 1MHz, L2 and C4 can be implemented using smaller components.

[0118] This DC / DC step-down circuit converts 12V to 5V with an efficiency of over 90%, providing a stable and clean power supply for the microcontroller.

[0119] The pulse signal acquisition circuit includes a fourth resistor, a fifth resistor, a fifth capacitor, and a transistor;

[0120] The signal output terminal of the turbine sensor is connected to the base of the transistor through the fourth resistor. The base of the transistor is grounded through the fifth resistor, and the base of the transistor is also grounded through the fifth capacitor.

[0121] The emitter of the transistor is grounded, and the collector of the transistor is connected to the pulse input pin of the microcontroller. At the same time, the collector of the transistor is connected to the output terminal of the DC / DC buck circuit through a pull-up resistor.

[0122] In practice, the output terminal SENSOR_OUT of the turbine sensor is connected to the base of transistor Q1 (NPN type, such as 9013) through the fourth resistor R4 (typical value 1kΩ);

[0123] The base of transistor Q1 is grounded through the fifth resistor R5 (typically 10kΩ);

[0124] The base of transistor Q1 is grounded through the fifth capacitor C5 (typical value 0.1μF);

[0125] The emitter of transistor Q1 is grounded;

[0126] The collector of transistor Q1 is used as the pulse output terminal PULSE_OUT and connected to the pulse input pin of the microcontroller.

[0127] The collector of transistor Q1 is connected to VCC5V via a pull-up resistor R_PULLUP (typically 4.7kΩ).

[0128] The working principle of the pulse signal acquisition circuit is:

[0129] Turbine sensing sensors typically employ Hall effect sensors or reed switches. When a magnet approaches, the sensor outputs a low-level (or high-level, depending on the type) pulse. This embodiment assumes the sensor output is a high-level pulse (low level when not triggered, high level when triggered).

[0130] When the turbine sensor does not output a pulse (in a stationary state), SENSOR_OUT is low, the base of transistor Q1 is low, transistor Q1 is cut off, its collector is pulled up to VCC5V by R_PULLUP, and PULSE_OUT is high.

[0131] When the turbine sensor outputs a high-level pulse, current flows into the base of transistor Q1 through the fourth resistor R4. Transistor Q1 is saturated and turned on, and its collector is pulled low to near 0V, causing PULSE_OUT to go low.

[0132] When the sensor pulse ends, transistor Q1 returns to cutoff, and PULSE_OUT returns to high level.

[0133] In this way, the sensor's raw pulse signal is converted into a falling edge or rising edge signal that the microcontroller can recognize. The fourth resistor R4 limits the base current to prevent overdrive of transistor Q1; the fifth resistor R5 ensures that the base voltage of transistor Q1 is 0 when there is no signal, avoiding false triggering; C5 filters out high-frequency noise and improves anti-interference capability.

[0134] The microcontroller can be configured with external interrupts or timer capture functions to count the level changes of the PULSE_OUT pin.

[0135] The relay drive circuit includes a sixth resistor, a seventh resistor, a sixth capacitor, and an N-channel MOSFET;

[0136] The microcontroller's control pin is connected to the gate of the N-channel MOSFET through the sixth resistor. The gate of the N-channel MOSFET is grounded through the seventh resistor, and the gate of the N-channel MOSFET is also grounded through the sixth capacitor.

[0137] The source of the N-channel MOSFET is grounded, and the drain of the N-channel MOSFET is connected to one end of the relay coil. The other end of the relay coil is connected to the output of the DC / DC step-down circuit.

[0138] A freewheeling diode is connected in parallel across the coil of the relay. The cathode of the freewheeling diode is connected to the output of the DC / DC step-down circuit, and the anode is connected to the drain of the N-channel MOSFET.

[0139] In practice, the microcontroller's control pin CTRL (e.g., P1.0) is connected to the gate of the N-channel MOSFET Q2 (e.g., AO3400, VDS=30V, ID=5.8A) through the sixth resistor R6 (typical value 1kΩ);

[0140] The gate of the N-channel MOSFET Q2 is grounded through the seventh resistor R7 (typically 10kΩ);

[0141] The gate of the N-channel MOSFET Q2 is grounded through the sixth capacitor C6 (typical value 0.1μF);

[0142] The source of N-channel MOSFET Q2 is grounded;

[0143] The drain of the N-channel MOSFET Q2 is connected to one end of the coil of the relay K1;

[0144] The other end of the coil of relay K1 is connected to VCC12V;

[0145] A freewheeling diode D3 (e.g., 1N4148 or 1N4007) is connected in parallel across the coil of relay K1. The cathode of D3 is connected to VCC12V, and the anode is connected to the drain of Q2.

[0146] The contact switch of relay K1 (e.g., a set of normally open contacts) is connected in series in the power supply circuit of the liquid pump motor. One end of the contact is connected to the AC power supply L_IN, and the other end is connected to the pump's L_OUT.

[0147] The working principle of the relay output circuit is:

[0148] Based on the flow rate determination, the microcontroller outputs a high level (5V) on the CTRL pin when the pump needs to be started. This high level is applied to the gate of Q2 through R6, making the gate-source voltage VGS of Q2 ≥ 2.5V (typical value), thus turning on Q2. After Q2 turns on, its drain voltage is pulled down to near 0V, and the coil of relay K1 receives approximately 12V. The coil current flows through Q2 to ground, the relay is energized, its normally open contact closes, the pump's power circuit is connected, and the pump begins to run.

[0149] When the microcontroller needs to stop the pump, it outputs a low level (0V) on the CTRL pin. The gate of Q2 discharges through R7, VGS drops below the threshold, and Q2 is turned off. The relay coil is de-energized, the contacts open, and the pump stops running.

[0150] When Q2 changes from conducting to cutoff, the current in the relay coil cannot change abruptly, resulting in a reverse induced electromotive force (V = L × di / dt) across the coil. This induced electromotive force can reach tens or even hundreds of volts, potentially damaging Q2. The freewheeling diode D3 provides a low-impedance freewheeling path for the coil current: when Q2 is cut off, the coil current forms a loop through D3, VCC12V, and ground, gradually attenuating and clamping the reverse voltage across the coil to within VCC12V + 0.7V, protecting Q2 from damage.

[0151] R6 is used to limit the gate drive current to prevent insufficient drive capability or overshoot; R7 ensures that Q2 is reliably cut off when the microcontroller outputs a high impedance state; C6 filters out high-frequency interference on the gate to prevent false triggering.

[0152] In practice, the turbine sensor is a water flow turbine sensor, which contains an impeller and a magnet. The impeller rotates under the drive of liquid flow, and the magnet generates a pulse signal when it approaches a Hall element or reed switch.

[0153] The turbine sensing sensor is installed in the outlet pipe of the liquid pump, and its specific structure is as follows:

[0154] A cylindrical outer shell with standard pipe thread interfaces (e.g., 4-point, 6-point, etc.) at both ends, which can be connected in series in a pipe;

[0155] An impeller is coaxially mounted inside the casing. The impeller has multiple blades. When the liquid flows, it impacts the blades and drives the impeller to rotate.

[0156] One or more permanent magnets are fixed on the central shaft of the impeller;

[0157] On the outside of the housing (or inside the sealed cavity), near the impeller, a Hall switch or reed switch is installed, with its signal line leading to the controller.

[0158] As the liquid flows, the impeller rotates, and each time the magnet passes the Hall element, the Hall element outputs a pulse (or a level flip). The pulse frequency f (Hz) is proportional to the liquid flow velocity v (m / s): f = k × v, where k is the sensor constant. Furthermore, the volumetric flow rate Q (m³ / s) is related to the flow velocity v and the pipe cross-sectional area A by Q = v × A, therefore the pulse frequency is proportional to the volumetric flow rate.

[0159] During factory calibration, a linear relationship between pulse frequency and flow rate can be established by measuring the number of pulses per unit time: Q (L / min) = α × f, where α is the calibration coefficient. The microcontroller uses this relationship to calculate the instantaneous flow rate.

[0160] Because of its small moment of inertia and fast response speed, the turbine can generate a detectable pulse signal even at low flow rates, making it suitable for pump start-stop control.

[0161] The microcontroller integrates a pulse counting module and a timer module. The pulse counting module is used to receive the number of pulses output by the pulse signal acquisition circuit, and the timer module is used to set the pulse sampling time window.

[0162] The microcontroller calculates the instantaneous flow rate value based on the number of pulses per unit time and a preset flow rate-pulse ratio, compares it with the preset start-up flow rate threshold and stop flow rate threshold, and outputs a start / stop control signal.

[0163] The AC power input terminal connects to an AC 85V~265V wide voltage input power supply.

[0164] The AC / DC step-down circuit outputs 12V DC, and the DC / DC step-down circuit outputs 5V DC.

[0165] The microcontroller operates at 5V, while the relay operates at 12V.

[0166] The microcontroller (e.g., the STC15W408AS, using an 8051 core, with built-in ADC, timer, and external interrupt) performs the following initialization operations after power-on:

[0167] Configure the system clock to an internal RC oscillator (e.g., 22.1184MHz).

[0168] Configure a timer (e.g., Timer0) as a 1ms interrupt to generate a time base and sampling window timing;

[0169] Configure external interrupt 0 (INT0) as falling edge triggered and connect it to the PULSE_OUT signal for pulse counting;

[0170] Configure an I / O port (e.g., P1.0) as a push-pull output and connect it to the CTRL terminal of the relay driver circuit;

[0171] Define the following internal variables: pulse_count (pulse count), flow_rate (instantaneous flow rate), pump_status (pump status), and stop_delay_counter (stop delay counter).

[0172] The main program flow of the microcontroller is as follows:

[0173] In each 1ms timer interrupt, the time counter is incremented. When the time counter reaches the sampling period (e.g., 1 second), pulse_count is multiplied by the calibration coefficient to obtain flow_rate (L / min), then pulse_count is cleared and the time counter is reset.

[0174] Determine the relationship between flow_rate and the set threshold:

[0175] If the pump is currently stopped and flow_rate > START_THRESHOLD (e.g., 5 L / min), then immediately set the CTRL pin high to start the pump and set the pump status to running.

[0176] If the pump is currently running and flow_rate < STOP_THRESHOLD (e.g., 2 L / min), a stop delay counter is started (e.g., a 2-second delay). During the delay, if flow_rate exceeds STOP_THRESHOLD again, the delay counter is cleared; if the delay counter reaches the set time, the CTRL pin is set low, the pump stops, and the pump status is set to stopped.

[0177] In the external interrupt 0 service routine, pulse_count is incremented by 1 for each falling edge detected.

[0178] Using the algorithm described above, the controller can reliably start and stop the pump based on the flow rate, avoiding malfunctions caused by instantaneous flow fluctuations or temporary air bubbles in the pipeline.

[0179] The following describes the working process of the automatic start / stop controller of the present invention in practical applications:

[0180] Initial state: The controller is powered on, the microcontroller is initialized, the pump is stopped, and there is no flow in the pipeline.

[0181] Start-up process: When the user turns on the tap or water-using equipment, liquid flows in the pipes.

[0182] The flowing liquid impacts the impeller inside the turbine sensor, causing the impeller to start rotating. The magnet periodically approaches the Hall element, and the sensor outputs a pulse signal.

[0183] The pulse signal acquisition circuit shapes the pulse and sends it to the external interrupt pin of the microcontroller.

[0184] If the microcontroller detects that the number of pulses exceeds the number of pulses corresponding to the start-up threshold (e.g., 50 pulses) within a 1-second sampling window, it determines that the flow rate is greater than 5 L / min.

[0185] When the microcontroller sets the CTRL pin to a high level, Q2 turns on, the relay is energized, the pump's power is switched on, and the pump starts running.

[0186] After the pump starts running, to maintain the flow of liquid in the pipeline, the turbine continuously outputs pulses, the microcontroller keeps CTRL at a high level, and the pump works continuously.

[0187] Stopping process: When the user turns off the tap, the liquid in the pipe gradually changes from flowing to still.

[0188] The turbine impeller speed decreases until it stops, and the pulse frequency decreases until it reaches zero.

[0189] If the microcontroller detects that the number of pulses is lower than the stop threshold (e.g., less than 20 pulses) within a 1-second sampling window, it determines that the flow rate is less than 2 L / min.

[0190] The microcontroller starts and stops a delay timer (2 seconds). If the number of pulses remains below the stop threshold within these 2 seconds, the microcontroller will set the CTRL pin low after the delay ends, Q2 will be cut off, the relay will be released, and the pump will be powered off and stopped.

[0191] If a pulse higher than the stop threshold is detected again during the delay period (e.g., the user briefly turns on the tap again), the delay is terminated and the pump continues to run.

[0192] Handling abnormal situations:

[0193] When air enters the pipeline, the gas drives the impeller to rotate (although less efficient than liquid, it still generates pulses). The microcontroller can still detect these pulses and maintain pump operation. The pump only stops when the gas stops flowing and the pulses disappear. Because air has a lower density, the driving force on the impeller is smaller, and the pulse frequency is lower than that of liquid, but this will not cause false shutdowns.

[0194] Even when the pipe is not full of liquid, the impeller will rotate as long as the liquid is still flowing (even in a gas-liquid two-phase flow), and the pulse signal can still be detected, so the controller works normally.

[0195] If the check valve leaks and causes a pressure drop after the pump stops, the controller will not start the pump if there is no flow, since it judges based on flow rate rather than pressure, thus avoiding frequent pump start-stop.

[0196] Through the above design, this invention achieves reliable, accurate, and widely adaptable automatic start-stop control of liquid pumps, completely solving the shortcomings of traditional pressure switches and simple electronic solutions.

[0197] In the above embodiments, the STC15W series microcontroller is selected, but other microcontrollers with pulse counting functions, such as STM8S003 and PIC16F1823, can also be selected, as long as the same function is achieved.

[0198] In the above embodiments, the turbine sensing sensor uses a Hall element output, or it can use a reed switch output. The pulse acquisition circuit is adjusted accordingly (the reed switch is a switching signal, which can be directly connected to a pull-up resistor and then sent to the microcontroller).

[0199] In the above embodiments, the relay output circuit is driven by an N-channel MOSFET, which can also be replaced by an NPN transistor (such as an 8050). However, the MOSFET has a lower on-state voltage drop and a higher current capability, making it more suitable for driving relays with higher power.

[0200] In the above embodiments, the AC / DC step-down circuit uses BP2522F, but other similar non-isolated step-down chips, such as AP8002 and PN8015, can also be used, with the connection relationships adjusted accordingly.

[0201] In the above embodiments, the DC / DC buck circuit uses ME3121AM6G, but other synchronous rectification buck chips such as SY8105 and RT8008 can also be used.

[0202] The beneficial effects of the present invention, through the design of the above embodiments, are as follows:

[0203] (1) No check valve required: The flow state of the liquid in the pipeline is directly detected by the turbine induction principle, rather than the pressure. Therefore, there is no need to use a check valve. Even if the check valve leaks air or water, it will not affect the normal operation of the controller, greatly reducing the dependence on pipeline accessories.

[0204] (2) Adaptable to incomplete pipe and air ingress conditions: When the pipe is not full of liquid or air enters, as long as there is still liquid flowing in the pipe, the turbine will rotate and generate a pulse signal, and the controller can work normally. The presence of air will not substantially interfere with the pulse signal, overcoming the defect that the pressure switch cannot work normally under such conditions.

[0205] (3) All-electronic structure, no mechanical fatigue problem: The mechanical structure such as springs is completely eliminated, and electronic induction and microcontroller control are adopted. The step-down circuit, pulse acquisition circuit and relay drive circuit are all solid-state electronic circuits, which do not have problems such as mechanical fatigue and elastic coefficient change. The long-term performance is stable and the failure rate is greatly reduced.

[0206] (4) Wide voltage input and good power supply adaptability: The AC / DC step-down circuit uses the BP2522F chip, which supports a wide range of AC input from 85V to 265V, and can adapt to the mains power standards of different countries and regions around the world. The DC / DC step-down circuit further stabilizes the output of 5V, ensuring the reliable operation of the microcontroller.

[0207] (5) High control precision: The microcontroller calculates flow rate through pulse counting and timers, which can accurately determine the start and stop of liquid flow. Compared with the fuzzy threshold of mechanical pressure switches, digital flow rate determination has higher precision and consistency.

[0208] (6) Applicable to all liquid pumps: It can be installed on the pipeline of any liquid pump and is controlled by sensing the liquid flow, without being limited by factors such as pump type, head, or power. At the same time, since it uses flow sensing instead of pressure sensing, it is not affected by pressure differences caused by the distance of the pipeline, and has a wider range of applications.

[0209] (7) It can protect the pump body and reduce energy consumption and noise: When the liquid stops flowing, the controller outputs a stop signal in time to stop the pump from running, avoiding wear and overheating caused by the pump running dry for a long time, and eliminating the noise generated by the pump running dry, thus saving energy.

[0210] (8) The circuit structure is clear and easy to implement: The circuit of this invention adopts mature step-down chips and standard transistor and MOSFET driving circuits. It has fewer components, lower cost, and higher reliability, making it suitable for mass production and widespread application.

[0211] This invention has been described with reference to specific embodiments, but those skilled in the art will understand that various changes and equivalent substitutions can be made without departing from the scope of the invention. Furthermore, numerous modifications can be made to this invention to suit specific applications without departing from its protection scope. Therefore, this invention is not limited to the specific embodiments disclosed herein, but includes all embodiments falling within the scope of the claims.

Claims

1. An automatic start / stop controller, characterized in that, include: The circuit consists of a step-down circuit, a pulse signal acquisition circuit, a microcontroller, and a relay output circuit, all electrically connected. The step-down circuit includes an AC / DC step-down circuit and a DC / DC step-down circuit; The input terminal of the AC / DC step-down circuit is connected to the AC power input terminal, and the output terminal of the AC / DC step-down circuit is connected to the input terminal of the DC / DC step-down circuit. The output terminal of the DC / DC step-down circuit is connected to the power supply pin of the microcontroller; The input terminal of the pulse signal acquisition circuit is connected to the signal output terminal of the turbine induction sensor, and the output terminal of the pulse signal acquisition circuit is connected to the pulse input pin of the microcontroller. The relay output circuit includes a relay and a relay driving circuit. The input terminal of the relay driving circuit is connected to the control pin of the microcontroller, and the output terminal of the relay driving circuit is connected to both ends of the relay coil. The contact switch of the relay is connected in series in the power supply circuit of the external liquid pump motor.

2. The automatic start / stop controller according to claim 1, characterized in that: The AC / DC step-down circuit includes a first step-down chip, a first inductor, a first capacitor, a second capacitor, a first diode, a second diode, and a first resistor; The DRAIN pin of the first step-down chip is connected to the high voltage input terminal of the rectified AC power supply. The VCC pin of the first step-down chip is grounded through the first capacitor. The SEL pin of the first step-down chip is grounded through the first resistor. The SOURCE pin of the first step-down chip is grounded. The DRAIN pin of the first step-down chip is also connected to the cathode of the first diode, the anode of the first diode is connected to the cathode of the second diode, and the anode of the second diode is grounded; A first inductor is connected between the SOURCE pin and the DRAIN pin of the first step-down chip; The connection point between the first inductor and the cathode of the first diode serves as the output terminal of the AC / DC step-down circuit, and this output terminal is grounded through the second capacitor.

3. The automatic start / stop controller according to claim 2, characterized in that: The SEL pin of the first step-down chip is grounded through a first resistor, so that the output voltage is locked at 12V; The first step-down chip integrates a 500V high-voltage MOSFET and adopts a non-isolated step-down AC-DC constant voltage topology.

4. The automatic start / stop controller according to claim 1, characterized in that: The DC / DC step-down circuit includes a second step-down chip, a second inductor, a third capacitor, a fourth capacitor, a second resistor, and a third resistor; The VIN pin of the second step-down chip is connected to the output terminal of the AC / DC step-down circuit and grounded through the third capacitor; The SW pin of the second step-down chip is connected to one end of the second inductor, and the other end of the second inductor serves as the output terminal of the DC / DC step-down circuit. This output terminal is grounded through the fourth capacitor. The FB pin of the second step-down chip is connected to the output terminal of the DC / DC step-down circuit through a second resistor, and is also grounded through a third resistor; The GND pin of the second buck converter is grounded, and the EN pin of the second buck converter is connected to its VIN pin.

5. The automatic start / stop controller according to claim 4, characterized in that: The second step-down chip integrates a high-side MOSFET and a low-side MOSFET, adopts a synchronous rectification step-down topology, and has a switching frequency of 1MHz; The internal reference voltage of the FB pin of the second step-down chip is 0.6V, and the output voltage is set by the ratio of the second resistor to the third resistor.

6. The automatic start / stop controller according to claim 1, characterized in that: The pulse signal acquisition circuit includes a fourth resistor, a fifth resistor, a fifth capacitor, and a transistor; The signal output terminal of the turbine sensor is connected to the base of the transistor through a fourth resistor. The base of the transistor is grounded through a fifth resistor, and the base of the transistor is also grounded through a fifth capacitor. The emitter of the transistor is grounded, the collector of the transistor is connected to the pulse input pin of the microcontroller, and the collector of the transistor is connected to the output terminal of the DC / DC buck circuit through a pull-up resistor.

7. The automatic start / stop controller according to claim 1, characterized in that: The relay drive circuit includes a sixth resistor, a seventh resistor, a sixth capacitor, and an N-channel MOSFET; The control pin of the microcontroller is connected to the gate of the N-channel MOSFET through the sixth resistor. The gate of the N-channel MOSFET is grounded through the seventh resistor. The gate of the N-channel MOSFET is also grounded through the sixth capacitor. The source of the N-channel MOSFET is grounded, and the drain of the N-channel MOSFET is connected to one end of the relay coil. The other end of the relay coil is connected to the output of the DC / DC step-down circuit. A freewheeling diode is connected in parallel across the coil of the relay. The cathode of the freewheeling diode is connected to the output terminal of the DC / DC step-down circuit, and the anode is connected to the drain of the N-channel MOSFET.

8. The automatic start / stop controller according to claim 1, characterized in that: The turbine sensor is a water flow turbine sensor, which has an impeller and a magnet inside. The impeller rotates under the drive of liquid flow, and the magnet generates a pulse signal when it is close to a Hall element or a reed switch.

9. The automatic start / stop controller according to claim 1, characterized in that: The microcontroller integrates a pulse counting module and a timer module. The pulse counting module is used to receive the number of pulses output by the pulse signal acquisition circuit, and the timer module is used to set the pulse sampling time window. The microcontroller calculates the instantaneous flow rate value based on the number of pulses per unit time according to a preset flow rate-pulse ratio, compares it with preset start flow rate thresholds and stop flow rate thresholds, and outputs start / stop control signals.

10. The automatic start / stop controller according to claim 1, characterized in that: The AC power input terminal is connected to an AC 85V~265V wide voltage input power supply; The AC / DC step-down circuit outputs 12V DC power, and the DC / DC step-down circuit outputs 5V DC power. The microcontroller operates at 5V, and the relay operates at 12V.

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