A siphon self-suction pipe and a control method thereof

Abstract

The application discloses a siphon type self-suction pipe-in-pump, which mainly comprises a pump body, a pump cavity formed in the pump body, a motor arranged in the pump cavity, an impeller arranged in the pump cavity and coaxially connected with the motor, a vacuum pump arranged on the pump body and connected with the pump cavity, and a control system arranged outside the pump body and used for controlling the start and stop of the motor and the vacuum pump and detecting the water level of the pump cavity and the impeller. The application further discloses a control method of the siphon type self-suction pipe-in-pump, which comprises the steps of connecting an external power supply, collecting water level information in the pump cavity, the impeller and a water inlet pipe by a liquid level sensor in real time, and transmitting the collected information to a signal control chip U for signal amplification processing. The siphon principle is applied to the pipe-in-pump by a technical method, so that the defect that the traditional pipe-in-pump must be filled with water before use can be completely overcome, and the preparation time of the pipe-in-pump can be greatly saved.

Description

Technical Field

[0001] This invention relates to a pipe pump, specifically a siphon-type self-priming pipe pump and its control method. Background Technology

[0002] Currently, with the progress of urbanization and the continuous improvement of rural living standards, the demand for building water supply equipment is also constantly rising, and in-line pumps have become an indispensable part of people's daily lives. However, existing in-line pumps and other traditional water pumps have the following three defects due to design reasons: First, they do not have a self-priming function. When using these in-line pumps, a check valve must be installed at the bottom of the pump's inlet pipe before filling the inlet pipe with water. Since there cannot be any air in the inlet pipe during pumping, the act of filling the inlet pipe with water often needs to be repeated several times to meet the usage requirements, which is a great waste of time. Second, traditional in-line pumps are prone to creating a vacuum state during operation. When there is no water in the pipeline or no water in the impeller, the pump's mechanical seal and motor will be damaged, resulting in a very high damage rate or failure rate, which is not conducive to promotion and use. Thirdly, traditional in-line pumps can only reach a maximum water-drawing height of about 4 meters during operation. When the height between the water tank and the pump exceeds 4 meters, the in-line pump can no longer be used effectively. This water-drawing height is far from meeting people's actual needs, and its use is very limited.

[0003] In summary, existing in-line pumps have many defects and cannot be widely promoted and used. Finding effective solutions to these problems is an urgent task. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention proposes a siphon-type self-priming pump and its control method.

[0005] The present invention provides the following technical solution: a siphon-type self-priming in-pipe pump, mainly composed of a pump body, a pump cavity formed inside the pump body, a motor installed inside the pump cavity, an impeller installed inside the pump cavity and coaxially connected to the motor, a vacuum pump installed on the pump body and connected to the pump cavity, and a control system installed outside the pump body for controlling the start and stop of the motor and the vacuum pump and for detecting the water level in the pump cavity and the impeller; the water inlet of the pump body is connected to the water inlet pipe, and a check valve is provided at the water outlet end of the pump body.

[0006] Furthermore, the control system comprises a power transformer circuit, a vacuum pump control circuit, a motor control circuit, a liquid level detection control circuit, and a motor signal control circuit connected to the power transformer circuit; the liquid level detection control circuit comprises an intermediate relay KA, a liquid level sensor, and a transistor switching circuit connected to the intermediate relay KA; the motor signal control circuit is connected to the transistor switching circuit through the normally open contact of the intermediate relay KA, and the liquid level sensor is connected to the transistor switching circuit and provides it with a liquid level signal.

[0007] The power transformer circuit consists of transformer T1, transformer T2, and a diode bridge rectifier circuit. The primary coil of transformer T1 is connected to phase A and phase B of the external power line, and its secondary coil is connected to the vacuum pump control circuit. The primary coil of transformer T2 is connected to phase B and phase C of the external power line, and its secondary coil is connected to the input terminal of the diode bridge rectifier circuit. The output terminal of the diode bridge rectifier circuit is connected to the liquid level detection and control circuit.

[0008] The motor control circuit consists of a fuse FU and a normally open contact of a contactor KM. One end of the normally open contact of the contactor KM is connected to the A-phase line, B-phase line and C-phase line of the external power line, respectively, and the other end is connected to the power control terminal of the motor via the fuse FU.

[0009] The motor signal control circuit consists of a contactor KM and the normally open contact of an intermediate relay KA. One end of the normally open contact of the intermediate relay KA is connected to the B phase line of the external power line, and the other end is connected to the A phase line of the external power line through the contactor KM to form an electrical circuit.

[0010] The vacuum pump control circuit consists of a time relay KT, a normally closed contact of the time relay KT, and a normally closed contact of a contactor KM. The time relay KT is connected in series across the two ends of the secondary coil of the transformer T1. One end of the power control terminal of the vacuum pump is connected to one end of the time relay KT, and the other end of the power control terminal of the vacuum pump is connected to the other end of the time relay KT via the normally closed contact of the contactor KM and the normally closed contact of the time relay KT in sequence, thus forming an electrical circuit.

[0011] The transistor switching circuit includes a signal control chip U, a filter circuit, capacitors C1 and C2, transistors VT1, VT2, and VT3, a diode T2, a resistor R3 connected at one end to pin 9 of the signal control chip U and at the base of transistor VT3, a resistor R4 connected at one end to pin 8 of the signal control chip U and at the base of transistor VT1, a resistor R1 connected at one end to the positive terminal of the diode bridge rectifier circuit output and at the collector of transistor VT3, a diode T1 with its N terminal connected to the positive terminal of the diode bridge rectifier circuit output and its P terminal connected to the collector of transistor VT2, and a diode T1 with one end connected to the positive terminal of the diode bridge rectifier circuit output and at the other end connected to the collector of transistor VT2. A capacitor C2 is connected to the collector of transistor VT2; the emitter of transistor VT3 is connected to the collector of transistor VT1 and the base of transistor VT2 respectively; the emitter of transistor VT2 is connected to the negative terminal of the output of the diode bridge rectifier circuit via diode T2; the emitter of transistor VT1 is connected to the negative terminal of the output of the diode bridge rectifier circuit; the capacitor C1 is connected in series between the positive and negative terminals of the output of the diode bridge rectifier circuit; the input terminal of the filter circuit is connected to the positive terminal of the output of the diode bridge rectifier circuit, and its output terminal is connected to pin 1 of the signal control chip U; one end of the intermediate relay KA is connected to the positive terminal of the output of the diode bridge rectifier circuit, and the other end is connected to the collector of transistor VT2.

[0012] To better protect the implementation of the present invention, the present invention also preferably provides a first induction protection circuit and a second induction protection circuit in the control system. The first induction protection circuit is composed of a current transformer L1, a diode T3, a resistor R5, a voltage stabilizing capacitor C6, and a capacitor C7. The current transformer L1 is mutually inducted with the C phase line of the external power line. The output terminal of the current transformer L1 is connected to pin 7 of the control chip U through diode T3 and resistor R5 in sequence. One end of the voltage stabilizing capacitor C6 is connected to the N terminal of diode T3 and the other end is grounded. One end of the capacitor C7 is connected to pin 7 of the control chip U and the other end is grounded.

[0013] The second inductive protection circuit consists of a current transformer L2, a diode T4, a resistor R6, a voltage stabilizing capacitor C8, and a capacitor C9. The current transformer L2 is mutually inducted with the A phase line of the external power line. The output terminal of the current transformer L2 is connected to pin 6 of the control chip U through diode T4 and resistor R6 in sequence. One end of the voltage stabilizing capacitor C8 is connected to the N terminal of diode T4, and the other end is grounded. One end of the capacitor C9 is connected to pin 6 of the control chip U, and the other end is grounded.

[0014] The number of liquid level sensors is three. One liquid level sensor is installed inside the water inlet pipe, another liquid level sensor is installed at the bottom of the pump chamber, and the third liquid level sensor is installed at the impeller position. All three liquid level sensors are connected to the signal control chip U, and the signal control chip U amplifies the liquid level signal transmitted by them.

[0015] The present invention also provides a method for controlling a pump in a siphon-type self-priming pipe, comprising the following steps:

[0016] S1. When the external power supply is turned on, the liquid level sensor collects the water level information in the pump chamber, impeller and inlet pipe in real time, and transmits the collected information to the signal control chip U for signal amplification processing.

[0017] S2. When the liquid level sensor sends a no-water signal, the signal control chip U simultaneously sends working voltage to transistors VT3 and VT1. The positive current at the output of the diode bridge rectifier circuit flows back to the negative terminal of the output of the diode bridge rectifier circuit after passing through resistor R1, transistor VT3 and transistor VT1 in sequence. The intermediate relay KA is short-circuited, the motor is in an open-circuit state, the vacuum pump starts and enters the working state, and the air in the pump chamber and the water inlet pipe is discharged.

[0018] S3. Water in the external water tank enters the inlet pipe of the in-pipe pump under atmospheric pressure, and rises into the pump chamber simultaneously with the discharge of air from the inlet pipe and the pump chamber.

[0019] S4. When the time relay KT ends a time cycle, its normally closed contact opens. The system determines whether there is water in the pump chamber and impeller. If so, the signal control chip U shuts off the operating voltage of transistor VT1. The positive current at the output of the diode bridge rectifier circuit is applied to the base of transistor VT2 through resistor R1 and transistor VT3. Transistor VT2 conducts, intermediate relay KA is turned on, the normally open contact of intermediate relay KA closes, contactor KM is energized, the normally open contact of contactor KM closes, and the motor starts working.

[0020] Furthermore, the first and second inductive protection circuits collect mutual inductance information of the external power lines in real time and determine whether the collected mutual inductance information exceeds the rated parameters. If the mutual inductance information of both phases does not exceed the rated parameters, no action is taken. If the mutual inductance information of any one phase exceeds the rated parameters, the signal control chip U turns on transistor VT1, transistors VT3 and VT1 are both turned on, transistor VT2 is short-circuited, the intermediate relay KA is short-circuited, the normally open contact of the intermediate relay KA opens from the closed state, the relay KM is de-energized, and the motor stops running.

[0021] The delay time of the time relay KT is 20 to 40 seconds, and the delay time of the time relay KT is inversely proportional to the diameter of the vacuum pump.

[0022] Compared with the prior art, the advantages and beneficial effects of this invention are:

[0023] 1. This invention innovatively applies the siphon principle to in-line pumps through technical methods, thereby completely overcoming the defect that traditional in-line pumps must first fill the pipeline with water before they can be used, and can greatly save preparation time when using in-line pumps.

[0024] 2. This invention eliminates the need to add a check valve at the bottom of the inlet pipe connected to the in-pipe pump during use, which greatly simplifies the usage process and significantly reduces the usage requirements of the in-pipe pump.

[0025] 3. The maximum siphon height (the height difference between the water tank and the pump in the pipe) of the present invention can reach 13m, which is far greater than the 4m water-drawing limit of the existing pump in the pipe. Its application scope is wider and it can adapt to various situations with different height differences. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0027] Figure 2 This is a schematic diagram of the control system circuit of the present invention.

[0028] The reference numerals in the above figures are as follows: 1—pump body, 2—pump chamber, 3—motor, 4—impeller, 5—vacuum pump, 6—control system, 7—inlet pipe, 8—check valve. Detailed Implementation

[0029] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Those skilled in the art will appreciate that these descriptions are merely descriptive and exemplary and should not be construed as limiting the scope of protection of the present invention.

[0030] Example 1

[0031] like Figure 1 As shown, the pump in the siphon self-priming pipe of the present invention mainly consists of a pump body 1, a pump chamber 2 formed inside the pump body 1, a motor 3 disposed inside the pump chamber 2, an impeller 4 disposed inside the pump chamber 2 and coaxially connected to the motor 3, a vacuum pump 5 disposed on the pump body 1 and connected to the pump chamber 2, and a control system 6 disposed outside the pump body 1 and used to control the motor 3, the impeller 4 and the vacuum pump 5.

[0032] The pump body 1 has an inlet and an outlet. The inlet is connected to an external inlet pipe 7, while a check valve 8 is installed at the outlet to prevent the discharged water from flowing back into the pump chamber 2. The vacuum pump 5 is connected to the pump chamber 2 inside the pump body 1. When the vacuum pump 5 starts, it expels air from the pump chamber 2 and the inlet pipe 7 outside the pump body 1, creating a vacuum negative pressure state. Under the influence of external atmospheric pressure, water in the pool is automatically drawn into the inlet pipe 7 through a siphon effect, thus achieving self-priming. When the impeller 4 detects water inside the pump chamber 2, it automatically starts the motor 3 to pump water.

[0033] The control system of this invention comprises a power transformer circuit, a vacuum pump control circuit, a motor control circuit, a liquid level detection control circuit, and a motor signal control circuit connected to the power transformer circuit. The liquid level detection control circuit consists of an intermediate relay KA, a liquid level sensor, and a transistor switching circuit connected to the intermediate relay KA. In connection, the motor signal control circuit is connected to the transistor switching circuit through the normally open contact of the intermediate relay KA. The liquid level sensor is connected to the transistor switching circuit and provides it with a liquid level signal. Its overall structure is as follows: Figure 2 As shown.

[0034] Specifically, the power transformer circuit consists of transformer T1, transformer T2, and a diode bridge rectifier circuit. One input terminal of the primary coil of transformer T1 is connected to phase A of the external power line, and the other input terminal is connected to phase B of the external power line. The secondary coil of transformer T1 is connected to the vacuum pump control circuit.

[0035] Similarly, one input terminal of the primary coil of transformer T2 is connected to the B phase line of the external power line, and the other input terminal is connected to the C phase line of the external power line. The secondary coil of transformer T2 is connected to the input terminal of the diode bridge rectifier circuit, and the output terminal of the diode bridge rectifier circuit is connected to the liquid level detection and control circuit.

[0036] In this invention, transformer T2 enables the output of the diode bridge rectifier circuit to output a 12V DC voltage. Similarly, transformer T1 enables its secondary coil to output a 24V voltage.

[0037] The motor signal control circuit consists of a contactor KM and the normally open contact of an intermediate relay KA. One end of the normally open contact of the intermediate relay KA is connected to the B phase line of the external power line, and the other end is connected to the A phase line of the external power line through the contactor KM to form an electrical circuit.

[0038] The delay time of the time relay KT in this invention is directly related to the actual situation and the pipe diameter of the vacuum pump 5. The delay time of the time relay KT is inversely proportional to the pipe diameter of the vacuum pump 5. That is, the larger the pipe diameter of the vacuum pump 5, the shorter the delay time of the time relay KT. The delay time of the time relay KT is preferably set between 20 and 40 seconds.

[0039] The vacuum pump control circuit consists of a time relay KT, a normally closed button of the time relay KT, and a normally closed contact of a contactor KM. One end of the power control terminal of the vacuum pump is connected to one end of the time relay KT, and the other end is connected to the other end of the time relay KT in sequence through the normally closed contact of the contactor KM and the normally closed button of the time relay KT to form an electrical circuit.

[0040] The motor control circuit consists of a fuse FU and a normally open contact of a contactor KM. One end of the normally open contact of the contactor KM is connected to the A-phase line, B-phase line and C-phase line of the external power line, respectively, and the other end is connected to the power control terminal of the motor 3 through the fuse FU.

[0041] The transistor switching circuit consists of a signal control chip U, a filter circuit, capacitors C1 and C2, transistors VT1, VT2, and VT3, diodes T1 and T2, and resistors R1, R3, and R4.

[0042] During connection, one end of resistor R3 is connected to pin 9 of signal control chip U, and the other end is connected to the base of transistor VT3. One end of resistor R4 is connected to pin 8 of signal control chip U, and the other end is connected to the base of transistor VT1. The resistance values ​​of resistors R3 and R4 are both 47KΩ. Resistor R1 has a resistance of 10KΩ, with one end connected to the positive terminal of the diode bridge rectifier circuit output and the other end connected to the collector of transistor VT3. One end of the intermediate relay KA is connected to the positive terminal of the diode bridge rectifier circuit output and the other end is connected to the collector of transistor VT2. The N terminal of diode T1 is connected to the positive terminal of the diode bridge rectifier circuit output, and the P terminal is connected to the collector of transistor VT2. The positive terminal of capacitor C2 is connected to the positive terminal of the diode bridge rectifier circuit output, and its negative terminal is connected to the collector of transistor VT2.

[0043] Meanwhile, to prevent the vacuum pump 5 and motor 3 from malfunctioning, the present invention also connects a capacitor C5 in series between the base of transistor VT3 and the negative terminal of the output of the diode bridge rectifier circuit, and a capacitor C3 in series between the base of transistor VT1 and the negative terminal of the output of the diode bridge rectifier circuit.

[0044] The emitter of transistor VT3 is connected to the collector of transistor VT1 and the base of transistor VT2. The emitter of transistor VT2 is connected to the negative terminal of the output of the diode bridge rectifier circuit via diode T2. The emitter of transistor VT1 is also connected to the negative terminal of the output of the diode bridge rectifier circuit. The capacitor C1 is connected in series between the positive and negative terminals of the output of the diode bridge rectifier circuit. The input terminal of the first filter circuit is connected to the positive terminal of the output of the diode bridge rectifier circuit, and its output terminal is connected to pin 1 of the signal control chip U.

[0045] The signal control chip U is implemented using an M324 integrated chip. The filter circuit consists of a resistor R2 and a capacitor C4. When connected, one end of the resistor R2 is connected to the positive terminal of the output of the diode bridge rectifier circuit, and the other end is connected to pin 1 of the signal control chip U. One end of the capacitor C4 is also connected to pin 1 of the signal control chip U, and the other end is grounded.

[0046] To prevent damage to the control system caused by overload of current and voltage in the external power line, the present invention also includes a first induction protection circuit and a second induction protection circuit.

[0047] The first inductive protection circuit consists of a current transformer L1, a diode T3, a resistor R5, a voltage-stabilizing capacitor C6, and a capacitor C7. During connection, the current transformer L1 is mutually inducted with the C-phase line of the external power line. The output terminal of the current transformer L1 is connected to pin 7 of the control chip U via diode T3 and resistor R5. One end of the voltage-stabilizing capacitor C6 is connected to the N-terminus of diode T3, and the other end is grounded. One end of the capacitor C7 is connected to pin 7 of the control chip U, and the other end is grounded.

[0048] The second inductive protection circuit consists of a current transformer L2, a diode T4, a resistor R6, a voltage stabilizing capacitor C8, and a capacitor C9. The current transformer L2 is mutually inducted with the A phase line of the external power line. The output terminal of the current transformer L2 is connected to pin 6 of the control chip U through diode T4 and resistor R6 in sequence. One end of the voltage stabilizing capacitor C8 is connected to the N terminal of diode T4, and the other end is grounded. One end of the capacitor C9 is connected to pin 6 of the control chip U, and the other end is grounded.

[0049] The liquid level detection and control circuit consists of three liquid level sensors. One liquid level sensor is located inside the water inlet pipe 7, another liquid level sensor is located at the bottom of the pump chamber 2, and the third liquid level sensor is located at the impeller 4. All three liquid level sensors are connected to the signal control chip U, and the signal control chip U amplifies the liquid level signals transmitted by them.

[0050] Example 2

[0051] This embodiment is a control method based on the circuit structure in Embodiment 1, which includes the following steps:

[0052] S1. When the external power supply is connected, the liquid level sensor collects water level information in the pump chamber, impeller, and inlet pipe in real time, and transmits the collected information to the signal control chip U for signal amplification processing. Connecting the external power supply in this step means that the power supply of the pump in the entire siphon self-priming pipe is connected to the external power line. After connection, all electronic components are in standby mode.

[0053] S2. When the liquid level sensor sends a no-water signal, the signal control chip U simultaneously sends working voltage to transistors VT3 and VT1. The positive current at the output of the diode bridge rectifier circuit flows back to the negative terminal of the output of the diode bridge rectifier circuit through resistor R1, transistor VT3 and transistor VT1 in sequence. The intermediate relay KA is short-circuited, the motor is in an open-circuit state, the vacuum pump starts and enters the working state, and the air in the pump chamber and water inlet pipe is discharged.

[0054] S3. Water from the external pool enters the inlet pipe of the in-tube pump under atmospheric pressure and rises synchronously into the pump chamber along with the air discharged from the inlet pipe and the pump chamber. Since the air in the pump chamber 2 and the inlet pipe 7 is discharged outside the in-tube pump by the vacuum pump 5, a negative pressure is formed in the pump chamber 2 and the inlet pipe 7. Due to the presence of external atmospheric pressure, a siphon phenomenon occurs, and the water in the pool rises along the inlet pipe 7 under atmospheric pressure and enters the pump chamber 2.

[0055] S4. At the end of a time cycle, the normally closed contact of the time relay KT opens. The system determines whether there is water in the pump chamber and impeller. If so, the signal control chip U shuts off the operating voltage of transistor VT1. The positive current at the output of the diode bridge rectifier circuit is applied to the base of transistor VT2 through resistor R1 and transistor VT3, causing transistor VT2 to conduct. The intermediate relay KA is then turned on, and its normally open contact closes, energizing contactor KM. The normally open contact of contactor KM closes, and the motor starts working. At this time, when contactor KM is energized, its normally closed contact opens, completely disconnecting the vacuum pump control circuit and stopping vacuum pump 5. Through this design, an interlock is formed between vacuum pump 5 and motor 3, meaning that only one pump can operate at a time, effectively preventing the pump chamber 2 from being evacuated and damaging the mechanical seal.

[0056] The delay time of the time relay KT is 20-40 seconds, and the delay time of the time relay KT is inversely proportional to the diameter of the vacuum pump 5. That is, when the diameter of the vacuum pump 5 is larger, it means that the vacuum pump 5 has a greater exhaust capacity, the air in the pump chamber 2 is discharged faster, and the delay time of the time relay KT is shorter; when the diameter of the vacuum pump 5 is smaller, it means that the vacuum pump 5 has a smaller exhaust capacity, the air in the pump chamber 2 is discharged slower, and the delay time of the time relay KT is longer.

[0057] To protect the control system from damage, during operation, the first and second inductive protection circuits of this invention will collect the mutual inductance information of the external power lines in real time and determine whether the collected mutual inductance information exceeds the rated specifications. If the mutual inductance information of phases A and C of the external power lines does not exceed the rated specifications, it indicates that the circuit is working normally, and no action is taken. If the mutual inductance information of any phase exceeds the rated specifications, the signal control chip U will conduct transistor VT1, transistors VT3 and VT1 will both be conducted, transistor VT2 will be short-circuited, the intermediate relay KA will be short-circuited, the normally open contact of the intermediate relay KA will open from the closed state, the relay KM will be de-energized, and the motor will stop running, thereby achieving the purpose of protecting the control system.

[0058] As described above, the present invention can be implemented well.

Claims

1. A siphon-type self-priming in-line pump, characterized in that, It mainly consists of a pump body (1), a pump chamber (2) formed inside the pump body (1), a motor (3) installed inside the pump chamber (2), an impeller (4) installed inside the pump chamber (2) and coaxially connected to the motor (3), a vacuum pump (5) installed on the pump body (1) and connected to the pump chamber (2), and a control system (6) installed outside the pump body (1) for controlling the start and stop of the motor (3) and the vacuum pump (5) and for detecting the water level of the pump chamber (2) and the impeller (4); the inlet of the pump body (1) is connected to the inlet pipe (7), and the outlet end of the pump body (1) is provided with a check valve (8); the control system consists of a power transformer circuit and a power transformer circuit connected to the pump body (1). This system comprises a vacuum pump control circuit, a motor control circuit, a liquid level detection control circuit, and a motor signal control circuit. The liquid level detection control circuit consists of an intermediate relay KA, a liquid level sensor, and a transistor switching circuit connected to the intermediate relay KA. The motor signal control circuit is connected to the transistor switching circuit via the normally open contact of the intermediate relay KA. The liquid level sensor is connected to the transistor switching circuit and provides it with a liquid level signal. The transistor switching circuit includes a signal control chip U, a filter circuit, capacitors C1 and C2, transistors VT1, VT2, and VT3, and a diode D2, one end of which is connected to the signal control chip U. The following resistors are connected: R3, with one end connected to pin 9 of the transistor and the other end connected to the base of transistor VT3; R4, with one end connected to pin 8 of the signal control chip U and the other end connected to the base of transistor VT1; R1, with one end connected to the positive terminal of the diode bridge rectifier circuit output and the other end connected to the collector of transistor VT3; D1, with its N terminal connected to the positive terminal of the diode bridge rectifier circuit output and its P terminal connected to the collector of transistor VT2; and C2, with one end connected to the positive terminal of the diode bridge rectifier circuit output and the other end connected to the collector of transistor VT2. The emitter of transistor VT3 is connected to three... The collector of transistor VT1 is connected to the base of transistor VT2. The emitter of transistor VT2 is connected to the negative terminal of the output of the diode bridge rectifier circuit via diode D2. The emitter of transistor VT1 is connected to the negative terminal of the output of the diode bridge rectifier circuit. The capacitor C1 is connected in series between the positive and negative terminals of the output of the diode bridge rectifier circuit. The input terminal of the filter circuit is connected to the positive terminal of the output of the diode bridge rectifier circuit, and its output terminal is connected to pin 1 of the signal control chip U. One end of the intermediate relay KA is connected to the positive terminal of the output of the diode bridge rectifier circuit, and the other end is connected to the collector of transistor VT2.

2. A siphon-type self-priming in-line pump according to claim 1, characterized in that, The power transformer circuit consists of transformer T1, transformer T2, and a diode bridge rectifier circuit. The primary coil of transformer T1 is connected to phase A and phase B of the external power line, and its secondary coil is connected to the vacuum pump control circuit. The primary coil of transformer T2 is connected to phase B and phase C of the external power line, and its secondary coil is connected to the input terminal of the diode bridge rectifier circuit. The output terminal of the diode bridge rectifier circuit is connected to the liquid level detection and control circuit. The motor control circuit consists of a fuse FU and a normally open contact of a contactor KM. One end of the normally open contact of the contactor KM is connected to the A-phase line, B-phase line and C-phase line of the external power line, respectively, and the other end is connected to the power control terminal of the motor (3) after passing through the fuse FU. The motor signal control circuit consists of a contactor KM and the normally open contact of an intermediate relay KA. One end of the normally open contact of the intermediate relay KA is connected to the B phase line of the external power line, and the other end is connected to the A phase line of the external power line through the contactor KM to form an electrical circuit.

3. A siphon-type self-priming pipe pump according to claim 2, characterized in that, The vacuum pump control circuit consists of a time relay KT, a normally closed contact of the time relay KT, and a normally closed contact of a contactor KM. The time relay KT is connected in series across the two ends of the secondary coil of the transformer T1. One end of the power control terminal of the vacuum pump is connected to one end of the time relay KT, and the other end of the power control terminal of the vacuum pump is connected to the other end of the time relay KT via the normally closed contact of the contactor KM and the normally closed contact of the time relay KT in sequence, thus forming an electrical circuit.

4. A siphon-type self-priming in-pipe pump according to claim 3, characterized in that, The control system also includes a first induction protection circuit and a second induction protection circuit. The first induction protection circuit consists of a current transformer L1, a diode D3, a resistor R5, a voltage stabilizing capacitor C6, and a capacitor C7. The current transformer L1 is mutually inducted with the C-phase line of the external power line. The output terminal of the current transformer L1 is connected to pin 7 of the control chip U via diode D3 and resistor R5 in sequence. One end of the voltage stabilizing capacitor C6 is connected to the N-terminus of diode D3, and the other end is grounded. One end of the capacitor C7 is connected to pin 7 of the control chip U, and the other end is grounded. The second inductive protection circuit consists of a current transformer L2, a diode D4, a resistor R6, a voltage stabilizing capacitor C8, and a capacitor C9. The current transformer L2 is mutually inducted with the A phase line of the external power line. The output terminal of the current transformer L2 is connected to pin 6 of the control chip U via diode D4 and resistor R6 in sequence. One end of the voltage stabilizing capacitor C8 is connected to the N terminal of diode D4, and the other end is grounded. One end of the capacitor C9 is connected to pin 6 of the control chip U, and the other end is grounded.

5. A siphon-type self-priming pipe pump according to claim 4, characterized in that, The number of liquid level sensors is three. One liquid level sensor is set inside the water inlet pipe (7), another liquid level sensor is set at the bottom of the pump chamber (2), and the third liquid level sensor is set at the position of the impeller (4). All three liquid level sensors are connected to the signal control chip U, and the signal control chip U amplifies the liquid level signal transmitted by them.

6. A control method for a siphon-type self-priming pump according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. When the external power supply is turned on, the liquid level sensor collects the water level information in the pump chamber, impeller and inlet pipe in real time, and transmits the collected information to the signal control chip U for signal amplification processing. S2. When the liquid level sensor sends a no-water signal, the signal control chip U simultaneously sends working voltage to transistors VT3 and VT1. The positive current at the output of the diode bridge rectifier circuit flows back to the negative terminal of the output of the diode bridge rectifier circuit after passing through resistor R1, transistor VT3 and transistor VT1 in sequence. The intermediate relay KA is short-circuited, the motor is in an open-circuit state, the vacuum pump starts and enters the working state, and the air in the pump chamber and the water inlet pipe is discharged. S3. Water in the external water tank enters the inlet pipe of the in-pipe pump under atmospheric pressure, and rises into the pump chamber simultaneously with the discharge of air from the inlet pipe and the pump chamber. S4. When the time relay KT ends a time cycle, its normally closed contact opens. The system determines whether there is water in the pump chamber and impeller. If so, the signal control chip U shuts off the operating voltage of transistor VT1. The positive current at the output of the diode bridge rectifier circuit is applied to the base of transistor VT2 through resistor R1 and transistor VT3. Transistor VT2 conducts, intermediate relay KA is turned on, the normally open contact of intermediate relay KA closes, contactor KM is energized, the normally open contact of contactor KM closes, and the motor starts working.

7. The control method for a pump in a siphon-type self-priming pipe according to claim 6, characterized in that, The first and second inductive protection circuits collect mutual inductance information of the external power lines in real time and determine whether the collected mutual inductance information exceeds the rated parameters. If the mutual inductance information of both phases does not exceed the rated parameters, no action is taken. If the mutual inductance information of any phase exceeds the rated parameters, the signal control chip U will turn on transistor VT1, transistors VT3 and VT1 will both be turned on, transistor VT2 will be short-circuited, the intermediate relay KA will be short-circuited, the normally open contact of the intermediate relay KA will open from the closed state, the relay KM will be de-energized, and the motor will stop running.

8. The control method for a pump in a siphon-type self-priming pipe according to claim 6, characterized in that, The delay time of the time relay KT is 20 to 40 seconds, and the delay time of the time relay KT is inversely proportional to the diameter of the vacuum pump (5).

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