Automatic water injection circuit for liquid level detection

Abstract

In order to solve the problems of high cost and poor reliability in the prior art, the utility model provides a liquid level detection automatic water injection circuit which comprises a power supply input circuit, a liquid level detection circuit and a motor control circuit, and the liquid level detection circuit comprises a liquid level detection wiring socket and a Schmitt trigger. A first pin of the liquid level detection connector socket is connected with a power supply through a resistor, a second pin of the liquid level detection connector socket is electrically connected with a second pin of the Schmitt trigger, and the motor control circuit is electrically connected with a third pin of the liquid level detection connector socket. Conventional devices are used, replacement is convenient, raw material cost is low, pure hardware control is achieved, reliability is high, and meanwhile, related functional modules such as liquid level alarm and the like can be conveniently added.

Description

Technical Field

[0001] This utility model relates to water level detection in a container space, and in particular to an automatic water injection circuit for liquid level detection. Background Technology

[0002] Water level monitoring within containers has wide applications in various fields, including industry, agriculture, and home automation. In industrial production, level monitoring is crucial for ensuring normal equipment operation and preventing issues such as overflow or dry running. In agricultural irrigation, water level monitoring effectively regulates the rational use of water resources. In home automation systems, monitoring the level of water tanks or pools helps users replenish water in a timely manner or prevents overflow.

[0003] However, in practical applications, while many high-precision liquid level sensors can provide relatively accurate water level measurements, they are expensive, especially in scenarios requiring large-scale deployment, resulting in high equipment procurement and maintenance costs. Furthermore, some technologies not only have expensive equipment themselves but also require complex installation and commissioning, increasing the overall cost. In complex environments, some liquid level sensors may also have lower reliability, malfunctioning due to environmental influences and thus affecting detection accuracy.

[0004] Some liquid level sensors may require regular maintenance or cleaning during use, especially in harsh environments such as sewage and chemical liquids, where sensor wear and contamination are more pronounced. This not only increases operating costs but may also lead to system downtime and impact production efficiency.

[0005] To address the above problems, Chinese utility model patent CN216668897U proposes a liquid level detection device and an automatic water filling device, including a liquid channel, the first end of which is disposed in the liquid within a water tank; an airtight channel connected to the second end of the liquid channel; an inductive structure connected to the airtight channel, used to adjust its inductance according to the gas pressure within the airtight channel; and an oscillation smoothing module connected to the inductive structure, used to form an oscillation circuit with the inductive structure to obtain an oscillation signal, and to smooth the oscillation signal to generate a liquid level detection pulse signal to obtain the liquid level in the water tank. However, the channel of this utility model is relatively complex, resulting in higher production difficulty and cost, and inconvenient subsequent maintenance. Utility Model Content

[0006] This invention mainly addresses the problems of high cost and poor reliability in existing technologies by providing an automatic water injection circuit for liquid level detection.

[0007] The above-mentioned technical problems of this utility model are mainly solved by the following technical solutions:

[0008] An automatic water filling circuit with liquid level detection includes a power input circuit with a power input socket, a liquid level detection circuit, and a motor control circuit. The liquid level detection circuit includes a liquid level detection wiring socket with 3 pins and a Schmitt trigger with 8 pins. The first pin of the liquid level detection wiring socket is connected to the power supply through a resistor. The second pin of the liquid level detection wiring socket is electrically connected to the second pin of the Schmitt trigger. The motor control circuit is electrically connected to the third pin of the liquid level detection wiring socket.

[0009] As a preferred embodiment, the Schmitt trigger has three resistors connected in series, which can divide the power supply voltage into three equal parts.

[0010] As a preferred embodiment, the Schmitt trigger includes an RS flip-flop, a C1 comparator, and a C2 comparator. The output of the C1 comparator is electrically connected to the R terminal of the RS flip-flop, and the output of the C2 comparator is electrically connected to the S terminal of the RS flip-flop.

[0011] As a preferred embodiment, the non-inverting input of comparator C1 is electrically connected to the inverting input of comparator C2 to obtain a Schmitt trigger.

[0012] As a preferred embodiment, the fourth pin of the Schmitt trigger is a reset pin, and the fourth pin of the Schmitt trigger is electrically connected to the power supply.

[0013] As a preferred embodiment, the fourth pin of the Schmitt trigger is also connected to ground with a filter capacitor for stable circuit operation.

[0014] As a preferred embodiment, a filter capacitor is connected to pin 5 of the Schmitt trigger to improve the stability of the circuit.

[0015] As a preferred embodiment, the first pin and the second pin of the motor docking socket are connected to both ends of the motor.

[0016] As a preferred embodiment, a motor operation indicator light is provided between the liquid level detection circuit and the motor control circuit, which illuminates when the motor is powered on.

[0017] As a preferred embodiment, the power input circuit is equipped with a power indicator light, which illuminates when the power is supplied.

[0018] Therefore, the advantages of this utility model are:

[0019] This invention uses conventional components, which are easy to replace, have low raw material costs, and are purely hardware controlled, ensuring high reliability. It also allows for the addition of related functional modules such as liquid level alarms. Attached Figure Description

[0020] Figure 1 This is a hardware diagram of this utility model.

[0021] Figure 2 This is a diagram of the internal structure of the Schmitt trigger of this utility model. Detailed Implementation

[0022] The technical solution of this utility model will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0023] Example 1:

[0024] Water level monitoring within containers has wide applications in various fields such as industry, agriculture, and home automation. For example, in industrial production, liquid level monitoring is crucial for ensuring the normal operation of equipment and preventing problems such as overflow or dry running; in agricultural irrigation, water level monitoring can effectively regulate the rational use of water resources; and in home automation systems, liquid level monitoring of water tanks or pools can help users replenish water in a timely manner or prevent water overflow.

[0025] Existing water level detection technologies mainly include electrode-type level sensors, float switch-type level sensors, ultrasonic level sensors, and pressure sensors. Each of these technologies has its advantages, but some problems still exist in practical applications:

[0026] While high-precision liquid level sensors (such as ultrasonic and laser sensors) can provide relatively accurate water level measurements, they are expensive, especially in scenarios requiring large-scale deployment, resulting in high equipment procurement and maintenance costs. Furthermore, some technologies (such as radar-based liquid level sensors) are not only expensive in themselves but also require complex installation and commissioning, further increasing the overall cost.

[0027] In complex environments, some level sensors exhibit lower reliability. For example, electrode-type sensors are susceptible to impurities, silt, or corrosive liquids in the water, leading to inaccurate measurements or sensor failure; float switches are prone to mechanical wear and jamming, causing them to malfunction; and ultrasonic sensors may experience signal attenuation or distortion in environments with foam, steam, or significant temperature variations, affecting detection accuracy.

[0028] Some liquid level sensors (such as float-type and pressure sensors) may require regular maintenance or cleaning during use, especially in harsh environments such as sewage and chemical liquids, where sensor wear and contamination are more pronounced. This not only increases operating costs but may also lead to system downtime and impact production efficiency.

[0029] In summary, although existing technologies have achieved certain results in water level detection, they still have many shortcomings in terms of cost, reliability, and maintenance. There is an urgent need for a more economical, reliable water level detection solution that is suitable for various complex environments.

[0030] To address the aforementioned problems, this utility model provides an automatic water filling circuit with liquid level detection, comprising a power input circuit with a power input socket CN1, a liquid level detection circuit, and a motor control circuit. The liquid level detection circuit includes a liquid level detection wiring socket CN2 with three pins and a Schmitt trigger with eight pins. The first pin of the liquid level detection wiring socket CN2 is connected to the power supply via a resistor, and the second pin of the liquid level detection wiring socket CN2 is electrically connected to the second pin of the Schmitt trigger. The motor control circuit is electrically connected to the third pin of the liquid level detection wiring socket CN2. High represents the highest water level setting, and Low represents the lowest water level setting.

[0031] The power input circuit used in this invention is simple in design, mainly consisting of a circuit with a power input socket CN1, which can be directly connected to an external power supply to provide a stable power input for the entire automatic water filling circuit. This design allows the circuit to adapt to different power standards, facilitating its wide application.

[0032] The liquid level detection circuit is the core component of this invention. It includes a three-pin liquid level detection wiring socket CN2 and an eight-pin Schmitt trigger. Pin 1 of the liquid level detection wiring socket CN2 is connected to the power supply via a resistor; this connection method simplifies circuit design and reduces the failure rate. Pin 2 is electrically connected to pin 2 of the Schmitt trigger, which processes the liquid level signal, improving signal processing stability and response speed. The use of the Schmitt trigger makes liquid level detection more accurate and effectively avoids malfunctions caused by water level fluctuations.

[0033] The motor control circuit is electrically connected to pin 3 of the liquid level detection wiring socket CN2, and controls the start and stop of the water pump according to the signal from the liquid level detection circuit. When the water level is lower than the set minimum point Low, the motor control circuit will be turned on to drive the water pump to work and automatically fill the water; when the water level reaches the set maximum point High, the motor control circuit will be turned off and the water pump will stop working, thereby preventing water overflow.

[0034] This design not only achieves pure hardware-based liquid level control but also allows for the easy addition of extra functional modules, such as liquid level alarms, as needed. The liquid level alarm module can issue audible and visual alarms when the water level is too high or too low, reminding users to take timely action and increasing system safety. Furthermore, because it uses common components, readily available substitutes can be found on the market, making maintenance and upgrades easier and further reducing user maintenance costs.

[0035] In summary, this invention's automatic water filling circuit for liquid level detection utilizes a Schmitt trigger to improve signal processing stability, employs conventional components to reduce costs, and employs a purely hardware-based control method to enhance system reliability. This design is not only suitable for home and small factory applications but can also be extended to larger-scale industrial applications, demonstrating significant potential for widespread adoption and practicality. This technology can substantially reduce the cost of liquid level control systems while ensuring efficient operation and long-term stability.

[0036] The Schmitt trigger has three resistors connected in series, each with a resistance of 5K ohms, which divides the power supply voltage into three equal parts. For ease of description, the two reference voltages are named VH and VL respectively. If the 5th pin CONT of the Schmitt trigger does not have an external fixed voltage Vco, then VH = 2 / 3Vcc and VL = 1 / 3Vcc. The table below shows the logic output table of the Schmitt trigger of this invention.

[0037]

[0038] The Schmitt trigger consists of an RS flip-flop, comparator C1, and comparator C2. The output voltage of C1 is Vc1, and the output voltage of C2 is Vc2. Pin 6 (THRES) of the Schmitt trigger is connected to the non-inverting input (IN1) of comparator C1, and pin 2 (TRIG) is connected to the inverting input (IN2) of comparator C2. The output of comparator C1 is electrically connected to the R terminal of the RS flip-flop, and the output of comparator C2 is electrically connected to the S terminal of the RS flip-flop. When the input voltage Vi is higher than VH, the output signal of comparator C1 activates the R terminal of the RS flip-flop, setting its output to low. When the input voltage Vi is lower than VL, the output signal of comparator C2 activates the S terminal of the RS flip-flop, setting its output to high. Connecting the non-inverting input of comparator C1 to the inverting input of comparator C2 as a new input Vi creates the Schmitt trigger. A filter capacitor is connected to pin 5 of the Schmitt trigger to suppress high-frequency noise and prevent false triggering.

[0039] Pin 4, RESET, of the Schmitt trigger is its reset pin. If RESET is connected low, the chip's output will also be low. Therefore, for stable circuit operation, pin 4 of the Schmitt trigger is electrically connected to the power supply Vcc to ensure it operates under normal conditions. Furthermore, to further enhance the circuit's anti-interference capability and stability, a filter capacitor is connected to ground at pin 4 of the Schmitt trigger. This filter capacitor effectively filters out high-frequency noise in the power supply, preventing malfunctions caused by power fluctuations or electromagnetic interference.

[0040] This Schmitt trigger-based water level control system design offers several advantages. First, compared to traditional water level control circuits, the Schmitt trigger, due to its hysteresis characteristic, maintains the stability of the output signal even with fluctuations or noise in the input signal, preventing malfunctions caused by external interference. Second, the Schmitt trigger simplifies circuit design, reducing reliance on complex components, thereby lowering circuit costs while also reducing complexity and potential failure points. Furthermore, the reliability and stability of the Schmitt trigger enable this design to operate stably for extended periods, making it suitable for applications requiring high stability.

[0041] Furthermore, the hysteresis characteristic of the Schmitt trigger can prevent frequent pump starts and stops due to water level fluctuations. Without hysteresis, even minor fluctuations in water level near the setpoint could frequently trigger pump starts and stops, increasing pump wear and potentially system energy consumption. The Schmitt trigger, with its appropriate hysteresis range, ensures the pump only responds when there is a significant change in water level, thus achieving a more robust control strategy.

[0042] Through the above design, the Schmitt trigger and comparator are combined to accurately achieve automatic water level control during the water level control process. When the water level is lower than the minimum set point (Low), the water level sensor detects this signal and transmits it to the C2 comparator connected to the Schmitt trigger. The comparator generates a low water level signal based on the comparison result between the input signal and the reference voltage. Upon receiving this low water level signal, the Schmitt trigger outputs a stable high-level signal, which is then sent to the motor control circuit, causing the control circuit to drive the water pump to start. After the water pump starts working, the water level gradually rises until it reaches the set maximum water level (High). When the water level reaches this preset point, the water level sensor also transmits a signal to the C1 comparator, which inputs the high water level signal to the Schmitt trigger. At this time, the output of the Schmitt trigger switches from high to low. The low-level signal is transmitted to the motor control circuit, controlling the water pump to stop working, preventing the water level from becoming too high or overflowing.

[0043] This invention utilizes the high sensitivity and stability of a Schmitt trigger to achieve automatic liquid level detection and control through a simple hardware circuit. This design is suitable not only for home and small factories but can also be extended to larger-scale industrial applications. This technology significantly reduces the cost of the liquid level control system while ensuring efficient operation and long-term stability. Furthermore, due to the use of common components, readily available substitutes are available on the market, making maintenance and upgrades easier and further reducing user maintenance costs.

[0044] The first pin of the motor docking socket CN3 and the second pin of the motor docking socket CN3 are connected to both ends of the motor, and the third pin of the motor docking socket CN3 is left unconnected.

[0045] A motor operation indicator light is provided between the liquid level detection circuit and the motor control circuit. When the motor is powered on and running, the motor operation indicator light is LED2. The power input circuit is provided with a power indicator light LED1, and when the power is turned on, the power indicator light is lit.

[0046] Embodiment 2:

[0047] Operating principle:

[0048] As Figure 1 shown, when the water level is higher than the High point, the power supply Vcc divides the voltage through the resistor. At this time, Vi > VH > VL. According to the Schmitt trigger logic output table, OUT = 0. At this time, Q1 is not conducting, the relay will not be attracted, and the motor will not work. Because the resistors R3, R5, and R6 limit the current, the motor operation indicator light LED2 will not be lit.

[0049] When the water level is lower than the High point and higher than the Low point, at this time Vcc is still connected to the Vi terminal, and the voltage is divided through the resistor. Vi > VH > VL. Looking up the table, OUT = 0, and Q1 is still not conducting. The relay is in the off state, and the motor still does not work. Because the current is too small, the motor operation indicator light LED2 will not emit light.

[0050] When the water level is lower than the Low point, the input terminal Vi is directly connected to the ground through the resistor R3. At this time, Vi < VL < VH, OUT = 1, Q1 conducts, Vcc is connected to the ground through the resistor R6 and the motor operation indicator light LED2, and the motor operation indicator light LED2 is lit. The relay is attracted, the motor works, and starts to fill water into the container.

[0051] When the water level is higher than the Low point and lower than the High point, because Q1 is still conducting, the level detected by the input terminal Vi is still a low level. At this time, Vi < VL < VH, OUT = 1, Q1 maintains the conducting state, the motor operation indicator light LED2 maintains the lit state, the relay maintains the attracted state, and the motor keeps filling water.

[0052] When the water level is higher than the High point, Vcc divides the voltage, and the level detected by the input terminal Vi becomes a high level. At this time, Vi > VH > VL, OUT = 0, Q1 becomes non-conducting again, the motor operation indicator light LED2 goes out, the relay disconnects, and the motor stops filling water.

[0053] Repeat in a cycle to keep the water level in the container within a safe and reasonable range.

[0054] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. An automatic water injection circuit for liquid level detection, characterized in that, The device includes a power input circuit with a power input socket, a liquid level detection circuit, and a motor control circuit. The liquid level detection circuit includes a liquid level detection wiring socket with 3 pins and a Schmitt trigger with 8 pins. The first pin of the liquid level detection wiring socket is connected to the power supply through a resistor. The second pin of the liquid level detection wiring socket is electrically connected to the second pin of the Schmitt trigger. The motor control circuit is electrically connected to the third pin of the liquid level detection wiring socket.

2. The automatic water injection circuit for liquid level detection according to claim 1, characterized in that, The Schmitt trigger has three resistors connected in series.

3. The automatic water injection circuit for liquid level detection according to claim 1, characterized in that, The Schmitt trigger includes an RS flip-flop, a C1 comparator, and a C2 comparator. The output of the C1 comparator is electrically connected to the R terminal of the RS flip-flop, and the output of the C2 comparator is electrically connected to the S terminal of the RS flip-flop.

4. The automatic water injection circuit for liquid level detection according to claim 3, characterized in that, The non-inverting input of comparator C1 is electrically connected to the inverting input of comparator C2.

5. The automatic water injection circuit for liquid level detection according to claim 1, characterized in that, The fourth pin of the Schmitt trigger is a reset pin, and the fourth pin of the Schmitt trigger is electrically connected to the power supply.

6. The automatic water injection circuit for liquid level detection according to claim 5, characterized in that, The fourth pin of the Schmitt trigger is also connected to ground via a filter capacitor.

7. An automatic water injection circuit for liquid level detection according to claim 1, 2, 3, or 5, characterized in that, A filter capacitor is connected to pin 5 of the Schmitt trigger.

8. The automatic water injection circuit for liquid level detection according to claim 1, characterized in that, The automatic water injection circuit for liquid level detection includes a motor, and the two ends of the motor are connected to the first pin and the second pin of the motor docking socket.

9. The automatic water injection circuit for liquid level detection according to claim 1, characterized in that, A motor operation indicator light is provided between the liquid level detection circuit and the motor control circuit.

10. The automatic water injection circuit for liquid level detection according to claim 1, characterized in that, The power input circuit is equipped with a power indicator light.

Images