Automatic stop small-flow pump without liquid level sensor

Abstract

The utility model belongs to the technical field of flow pumps, and particularly relates to an automatic stop small-flow pump without a liquid level sensor. Comprising a pump body, a motor in driving connection with the pump body, and an MCU controller, the MCU controller is in circuit connection with the motor through a motor driving circuit, the MCU controller and the motor are connected to a power supply to be electrified, an I / V converter used for driving current sampling is connected in series between the motor driving circuit and the grounding end of the motor, and the I / V converter is connected with the motor. And the I / V converter is connected to the MCU controller in an electric signal manner through the primary filter circuit and the secondary filter circuit which are sequentially connected in series. The utility model provides a motor shutdown control scheme for detecting the water consumption condition without a liquid level sensor for the small-flow pump, reasonably solves the problem of low automatic control accuracy of the small-flow pump without the liquid level sensor, and has better application value.

Description

Technical Field

[0001] The utility model belongs to the technical field of flow pumps, and in particular relates to an automatic shutdown small flow pump without a liquid level sensor. Background Art

[0002] Generally speaking, in high-flow pumps, detecting changes in the motor's current to determine whether a pool or tank is completely drained, thus automatically stopping the motor, is a feasible and established technology. This technology works by assuming that the pump's operating current during idling is approximately half, or even less than, its normal operating current, enabling water usage monitoring.

[0003] In other words, because the current difference between the pump body when it is working normally (with water) and when it is no-load (without water) is very large, and the ratio of the two values ​​is ≥2, this change can be easily detected by the current detection device. Therefore, in reality, the equipment designer can judge the water consumption based on this current change and control the motor to stop, thereby achieving the effect of not using sensors, and its circuit and control program will be simplified.

[0004] However, low-flow, light-load pumps, such as those used in water flossers, are common in small, portable electronic products. These pumps require optimized detection circuits and complex programming to achieve sensorless, waterless automatic stop. Specifically, the water tank capacity of a water flosser is typically only 200 ml, the full water depth is only about 100 mm, and the suction pipe diameter is approximately 2 mm. This results in a very low water flow rate when operating a low-flow pump. Because of the low water flow rate, the motor only requires a small current to pump water properly. This results in a much smaller current distinction from no-load (no water) current than with high-flow pumps. Therefore, using high-flow pumps to detect water usage is prone to misjudgment.

[0005] For small flow pump products, how to achieve automatic shutdown of DC brush motors when there is no water without adding additional liquid level sensors / switches is a technical problem worth exploring and solving. Utility Model Content

[0006] In view of the technical defects existing in the background technology, the present invention proposes an automatic shutdown low-flow pump without a liquid level sensor, which solves the above technical problems and meets practical needs. The specific technical solution is as follows:

[0007] A liquid level sensor-free, automatic shutdown, low-flow pump comprises a pump body, a motor driveably connected to the pump body, and an MCU controller. The MCU controller is connected to a motor circuit via a motor drive circuit. The MCU controller and the motor are connected to a power supply for energization. An I / V converter for driving current sampling and connected to a driving current sampling unit is connected in series between the motor drive circuit and the motor ground terminal. The I / V converter is connected to the MCU controller via an electrical signal via a primary filter circuit and a secondary filter circuit connected in series. The resistance of the I / V converter is ≤20mΩ. The I / V converter is used to detect the motor load condition, and the MCU controller controls the motor to continue operating or stop according to the motor load condition detected by the driving current sampling unit.

[0008] As a further technical solution of the present invention, the first-stage filtering circuit is an inverted L-type filtering circuit, which includes a resistor R2 connected in series between the I / V converter and the MCU controller. The resistor R2 is provided with a signal input end and a signal output end, and a grounded capacitor C4 is connected to the signal input end of the resistor R2.

[0009] As a further technical solution of the present invention, the secondary filtering circuit is a π-type filtering circuit, which includes a resistor R1 connected in series between the I / V converter and the MCU controller. The resistor R1 is provided with a signal input end and a signal output end. The signal input end of the resistor R1 is connected in series with the signal output end of the resistor R2. A grounded capacitor C3 is connected to the signal input end of the resistor R1, and capacitors C1 and C2, which are connected in parallel and also grounded, are connected to the signal output end of the resistor R1.

[0010] As a further technical solution of the present invention, the capacitor C1 is larger than the capacitor C2, and the specification of the capacitor C1 is 10 times that of the capacitor C2.

[0011] As a further technical solution of the present invention, the I / V converter is provided with a sampling resistor, and the I / V converter is used to repeatedly sample the ADC value of the electrical signal under no-load and load conditions of the motor for the MCU controller to judge the motor load condition.

[0012] The utility model is provided with a sampling unit that can sample the ADC value of the motor load for the MCU controller to judge the motor load. On the basis of the sampling unit, it is equipped with an optimized control algorithm, so that the MCU controller can accurately judge whether the motor load condition meets the no-load condition, thereby achieving the technical effect of automatic shutdown even without a liquid level sensor in small current and light load pump products. The circuit cost is low and the performance is reliable, so it has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a structural diagram of the automatic shutdown small flow pump system described in the present utility model.

[0014] Figure 2 This is a circuit diagram of the first and second level filter circuits for sampling the automatic shutdown small flow pump described in the present utility model.

[0015] Figure 3 This is a flow chart for calibrating the corresponding signal ADC values ​​when there is water and when there is no water for the automatic shutdown low-flow pump described in the present utility model.

[0016] Figure 4 This is a flow chart of the automatic shutdown low-flow pump described in the present invention for controlling the motor according to the signal ADC value.

[0017] Figure 5 This is a flow chart of the automatic shutdown small flow pump optimization control algorithm described in the present utility model. DETAILED DESCRIPTION

[0018] The following describes the implementation of the present invention in conjunction with the accompanying drawings and relevant embodiments. The implementation of the present invention is not limited to the following embodiments, and the present invention involves relevant necessary components in this technical field, which should be regarded as common knowledge in this technical field and can be known and mastered by technical personnel in this technical field.

[0019] The utility model discloses an automatic shutdown low-flow pump without a liquid level sensor, comprising a pump body, a motor connected to the pump body drive, and an MCU controller. The MCU controller is connected to the motor circuit via a motor drive circuit, the MCU controller and the motor are connected to a power supply for energizing, an I / V converter for driving current sampling is connected in series between the motor drive circuit and the motor ground terminal, the I / V converter is connected to the MCU controller via an electrical signal via a primary filter circuit and a secondary filter circuit connected in series, the resistance of the I / V converter is ≤20mΩ, the I / V converter is used to detect the motor load condition, and the MCU controller controls the motor to continue running or stop according to the motor load condition detected by the drive current sampling unit.

[0020] This solution takes a water flosser as an example, but it is not limited to water flossers. It can also be implemented on other small-flow, light-load pump products, such as small coffee machines, water dispensers, etc., which are all within the scope of protection of this patent.

[0021] The irrigator consists of two main parts: the upper part houses the nozzle, MCU controller circuitry, and a brushed DC motor. The lower part houses the water tank. These two parts can be separated for easy filling and portability. To use the device, the water tank can be removed, filled with water, and then reattached to the upper part. Pressing the start switch activates the brushed DC motor, which drives the water pump. Water from the tank is ejected from the upper nozzle, flushing away dirt from the teeth.

[0022] At present, the electric irrigator on the market usually stops working after the start button is pressed and the programmed time, usually 90 seconds, is reached. This often leads to the following situation:

[0023] The water tank has been emptied, but the motor is still running because the 90-second timer has not yet expired. At this time, the user can either press the stop button specifically or let the product motor continue to run and wait for the set timer to expire for the product to stop working.

[0024] If you need to press the stop button to stop the motor from idling, it will affect the user experience. If the motor is left idling, it may take tens of seconds or even a minute to stop working, resulting in wasted energy. Moreover, oral irrigators are generally powered by lithium batteries, which have limited capacity. Wasted energy will reduce the user's effective use and require frequent charging.

[0025] The above phenomenon can be said to be a common defect of the oral irrigators currently on the market. In order to solve this problem, the oral irrigator needs to be able to automatically stop working when the water in the water tank is pumped out.

[0026] This article proposes a technical solution that can automatically stop the water supply when there is no water, without the need for an external liquid level sensor or switch. It also proposes a further optimized software algorithm to solve the problem of water / no water identification in low-flow and light-load pumps.

[0027] The system mainly includes four main parts: power supply, MCU controller, motor drive circuit, and DC brushed motor. In addition, there are circuits such as I / V conversion and signal filtering.

[0028] The power supply part is responsible for providing appropriate operating voltage and current to each part of the circuit. The MCU main control part identifies and judges the user's key actions, and outputs the control signal corresponding to the key to the motor drive circuit to control the start / stop of the motor.

[0029] The circuit part for detecting water / no water is composed of an I / V converter connected to the drive current sampling and a signal filtering circuit. The I / V converter is provided with a sampling resistor. The I / V converter is used to multiple times sample the ADC values ​​of the electrical signal under no-load and load conditions of the motor for the MCU controller to judge the motor load condition.

[0030] This solution determines the presence of water by measuring the slight difference between the motor's normal operating current (with water) and its no-load current (without water). Since the MCU can only process voltage signals, the motor's current signal is first converted to a voltage signal using an I / V conversion circuit. A sampling resistor is added to the motor's circuit, connected to GND (power ground). Assuming its resistance is R, the motor's operating current is I, and the resistor voltage is V, then V = IR. The sampling resistor's resistance is typically in the milliohm range. Choosing a higher value reduces the motor's drive current, weakening its ability to drive the motor.

[0031] The I / V converter converts the circuit's output signal, which is then processed by a signal filtering circuit before being sent to the MCU controller. This signal filtering circuit is crucial for low-flow, light-load pumps because the motor's operating current typically contains pulsating components. This is especially true for products like water flossers that use PWM speed regulation. This pulsating current, after passing through the I / V converter, becomes a rippled voltage signal. This can interfere with the MCU's ability to detect the motor's operating current. The filtering circuit removes this ripple, thereby outputting a cleaner signal to the MCU controller.

[0032] Furthermore, the first-level filtering circuit is an inverted L-type filtering circuit, which includes a resistor R2 connected in series between the I / V converter and the MCU controller, the resistor R2 is provided with a signal input end and a signal output end, and a grounded capacitor C4 is connected to the signal input end of the resistor R2; the second-level filtering circuit is a π-type filtering circuit, which includes a resistor R1 connected in series between the I / V converter and the MCU controller, the resistor R1 is provided with a signal input end and a signal output end, the signal input end of the resistor R1 is connected in series with the signal output end of the resistor R2, a grounded capacitor C3 is connected to the signal input end of the resistor R1, and capacitors C1 and C2, which are connected in parallel and also grounded, are connected to the signal output end of the resistor R1.

[0033] As a further technical solution of the present invention, the capacitor C1 is larger than the capacitor C2, and the specification of the capacitor C1 is 10 times that of the capacitor C2. As a specific preferred specification parameter, refer to Figure 2 As shown, the resistor R1 is 10KΩ, the resistor R2 is 2KΩ, the capacitor C1 is 10μF, the capacitor C2 is 0.1μF, the capacitor C3 is 10μF, and the capacitor C4 is 0.1μF.

[0034] To address low-flow, light-load pump products, this solution utilizes a first-stage inverted L-shaped filter circuit, followed by a second-stage π-shaped filter circuit. Two filter capacitors, one large and one small, achieve filtering over a wide frequency range. The large capacitor removes interference caused by fluid fluctuations, while the small capacitor removes PWM pulsation interference. The output signal from the I / V conversion circuit is fed into the filter circuit's signal input terminal. It undergoes initial filtering in the inverted L-shaped first-stage filter circuit, resulting in a cleaner signal that is then sent to the π-shaped second-stage filter circuit for secondary filtering. This two-stage filter eliminates interference superimposed on the signal before transmitting the signal to the MCU controller for processing. The filter circuit component parameters can be adjusted slightly to suit different products.

[0035] In combination with the existing circuit structure of the present invention, the software is designed to address the low differentiation between the loaded and no-load currents of small-flow and light-load pumps, and a water / no-water discrimination method and further optimization algorithm are proposed to effectively avoid misjudgment of water / no-water. In the present invention, the signal after the filtering circuit is input into the MCU controller, and through the internal ADC analog / digital converter circuit of the MCU controller, combined with the corresponding ADC value reading program, the voltage of the input signal is converted into an ADC value, read out, and processed.

[0036] For small-flow, light-load pump products, since the current of the motor during normal pumping is a small value and slightly different from the no-load (no water) current, more complex processing is required in the software. The drive current sampling unit that supports current sampling through algorithm control is the hardware condition of the utility model and is the fundamental reason why the utility model can enable the MCU controller to realize intelligent control of motor start and stop without the need for sensors.

[0037] Furthermore, the I / V converter is used to repeatedly sample the ADC value of the motor's no-load and load conditions for the MCU controller to determine the motor load condition, wherein a sampling resistor is provided, combined with Figure 3 As shown, when the motor is working in a water-containing state, the signal ADC value read by the program is represented by K_water. When the motor is working in a water-free state, the signal ADC value read by the program is represented by K_empty.

[0038] When calibrating K_water and K_empty, for low-flow, light-load pumps, the difference between the normal pumping current and the no-load (no-water) current is relatively subtle, so the signal ADC value must be read N times. For the water state, the minimum value among the obtained data is taken as K_water; for the no-water state, the maximum value among the obtained data is taken as K_empty.

[0039] Because when there is water, the resistance when the motor rotates is greater than when there is no water, the working current of the motor at this time will be greater than when there is no water. According to V = IR described in the first part, the greater the working current of the motor, the greater the voltage value of the signal and the corresponding ADC value. Therefore, K_water > K_empty. Based on these two data above, it is also necessary to set a very important key parameter K_judge, and the value of K_judge should satisfy: K_empty < K_judge < K_water.

[0040] Combined with Figure 4 As shown, according to the difference law of the current values measured when the motor is with / without water, the solution idea of this scheme is as follows: Once the MCU controller starts the motor to rotate, after a few seconds of delay, it continuously reads the input signal ADC value, and reversely deduces whether there is water in the water tank based on the read signal ADC value. The delay time needs to be adjusted according to different products. For example, for motors with relatively large specifications, the delay time can be correspondingly extended, while for motors with relatively small specifications, the delay time can be correspondingly shortened. If the read signal ADC value > K_judge, it means there is water and continue to work. If the read signal ADC value < K_judge, it means there is no water and immediately stop the motor from working to avoid idling.

[0041] Furthermore, an algorithm is adopted for optimization to avoid misjudgment of water presence / absence. Based on the hardware conditions of the present invention, combined with Figure 5 As shown, in actual application, during the process of the motor working to pump water, water is a fluid, so the current of the motor will fluctuate accordingly. Since the current of small flow pump types is not large itself, the impact of these fluctuations on small flow and light load pump products is more serious. The filtering circuit cannot completely filter out these fluctuations, and sometimes the signal ADC value read by the MCU controller deviates greatly from the normal value. If there is no corresponding algorithm in the software for optimization, there will be more misjudgments when identifying water presence / absence in small flow and light load pump products.

[0042] Therefore, a further software algorithm is proposed for optimization to avoid misjudgment of water presence and absence. After the MCU controller starts the motor, it continuously reads the signal ADC value. Once the read signal ADC value < K_judge, set EmptyCheckEN to 1, indicating the start of a no - water detection cycle.

[0043] The number of times the ADC value of the periodic read signal is represented by the variable EmptyADC_CNT. Each time the ADC value of the signal is read, the variable EmptyADC_CNT is incremented by 1. If the ADC value of this signal < K_judge, then the variable Empty_CNT representing the number of times without water is incremented by 1. There are N readings of the voltage ADC value in one no-water detection cycle, where N = 50. Of course, other values can also be set. Theoretically, the larger the value of N, the more accurate it is, but correspondingly, the no-water detection cycle will also become longer, and the reaction speed of stopping the machine when there is no water will become slower. Generally speaking, 50 times is a relatively reasonable total number of readings.

[0044] At the end of the no-water detection cycle, that is, when EmptyADC_CNT is incremented to reach N times (here N = 50), if Empty_CNT > 40, it means that there is an 80% probability (50 x 80% = 40) that the ADC value of the voltage read < K_judge in 50 times. At this time, the MCU can determine that the water tank is without water and then allow the control motor to stop working. The above scheme effectively filters the influence of local data fluctuations caused by external factors on the overall data by calculating the probability, so it can avoid the misjudgment of water presence / absence to the greatest extent.

[0045] In summary, the sampling unit of the present utility model that can sample the ADC value of the motor load, based on the double-stage signal filtering circuit, is used for the MCU controller to judge the motor load. And this sampling unit supports the writing of a reasonable control algorithm. By using an optimized control algorithm, the MCU controller can accurately judge whether the motor load situation meets the no-load condition, and then achieve the effect of automatic shutdown without a liquid level sensor in small-current and light-load pump products. The circuit cost is low and the performance is reliable, so it has a good application prospect.

[0046] The above are only the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present utility model, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present utility model.

Claims

1. A liquid level sensor-free automatic shutdown low-flow pump, comprising a pump body, a motor connected to the pump body, and an MCU controller, wherein the MCU controller is connected to the motor circuit via a motor drive circuit, and the MCU controller and the motor are connected to a power supply for powering, characterized in that: An I / V converter for driving current sampling is connected in series between the motor drive circuit and the motor ground terminal. The I / V converter is connected to the MCU controller by an electrical signal through a primary filter circuit and a secondary filter circuit connected in series. The resistance of the I / V converter is ≤20mΩ. The I / V converter is used to repeatedly detect the motor load condition, and the MCU controller controls the motor to continue running or stop according to the motor load condition detected by the driving current sampling unit.

2. The automatic shutdown low-flow pump without liquid level sensor according to claim 1 is characterized in that: The first-stage filter circuit is an inverted L-type filter circuit, which includes a resistor R2 connected in series between the I / V converter and the MCU controller. The resistor R2 is provided with a signal input end and a signal output end, and a grounded capacitor C4 is connected to the signal input end of the resistor R2.

3. The automatic shutdown low-flow pump without liquid level sensor according to claim 2, characterized in that: The secondary filtering circuit is a π-type filtering circuit, which includes a resistor R1 connected in series between the I / V converter and the MCU controller. The resistor R1 is provided with a signal input end and a signal output end. The signal input end of the resistor R1 is connected in series with the signal output end of the resistor R2. A grounded capacitor C3 is connected to the signal input end of the resistor R1, and capacitors C1 and C2, which are connected in parallel and also grounded, are connected to the signal output end of the resistor R1.

4. The automatic shutdown low-flow pump without liquid level sensor according to claim 3, characterized in that: The capacitor C1 is larger than the capacitor C2, and the specification of the capacitor C1 is 10 times that of the capacitor C2.

5. The automatic shutdown low-flow pump without liquid level sensor according to claim 1, characterized in that: The I / V converter is provided with a sampling resistor, and the I / V converter is used to sample the ADC value of the electrical signal under no-load and load conditions of the motor for the MCU controller to judge the motor load condition.

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