Large-caliber pilot-operated type normally-open electromagnetic valve

Abstract

The utility model relates to the technical field of electromagnetic valves, in particular to a large-diameter pilot-operated type normally-open electromagnetic valve which comprises a valve body, a top cover, a bottom cover, a valve element assembly, a magnetism isolating pipe, a coil and a normally-open spring, the valve body and the top cover form a main valve cavity and are connected with an outlet cavity through a main valve port, the valve element assembly is located in the main valve cavity, and the magnetism isolating pipe is connected with the coil. Comprising a piston, a valve rod, a connecting valve plate, a lower movable iron core, a valve port sealing piece, a connecting rod and an iron core spring, the piston and a bottom cover form a balance cavity, and the valve rod is connected with the piston and the connecting valve plate. Under the action of electromagnetic force, the upper movable iron core presses the lower movable iron core, the pilot valve port is closed firstly, then the valve element assembly moves downwards to close the main valve port under the action of pressure difference, as the section of the pilot valve port is far smaller than that of the main valve port, the electromagnetic force needed for closing the pilot valve port is very small, the power of a coil can be smaller, the structure is simple, the failure rate is low, and the cost is low. Reliability is high, using pressure is high, and coil power is low.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic valves, in particular to a large-caliber pilot-operated normally open electromagnetic valve. Background Art

[0002] Solenoid valves are basic automation components used to control fluids and are actuators. Normally open solenoid valves are a type of solenoid valve, characterized by the solenoid valve opening when the coil is de-energized and closing when the coil is energized. When selecting a solenoid valve, if the solenoid valve needs to be in the open state for a long time, or the open time is longer than the closed time, a normally open solenoid valve can often be selected to avoid the coil from being overheated and burned due to long-term energization of the coil.

[0003] For example, Chinese patent CN207064775U discloses a large-caliber multi-stage pilot high-pressure solenoid valve, which relates to the technical field of solenoid valves, including a valve body, a main valve port, a piston guide sleeve, a piston assembly, a large valve cover and a multi-stage pilot solenoid assembly. The main valve port is arranged inside the water outlet hole of the valve body, the piston guide sleeve is arranged in the valve body cavity, the piston assembly is arranged inside the piston guide sleeve and is located at the upper part of the main valve port, the large valve cover is fixed to the top of the valve body, the multi-stage pilot solenoid assembly is arranged at the upper end of the large valve cover, the multi-stage pilot solenoid assembly includes a secondary pilot assembly and an electromagnetic pilot assembly, a large balancing hole is provided on the large valve cover, the inner cavity of the piston assembly is connected with the multi-stage pilot solenoid assembly, the secondary pilot assembly and the electromagnetic pilot assembly are connected through the balancing hole, the main valve port is opened by multiple valve openings and multiple pressure reliefs, and the purpose of opening the large-caliber solenoid valve with a miniature small coil is well achieved.

[0004] The above-mentioned solenoid valve is relatively common. Compared with the normally closed solenoid valve, the normally open solenoid valve has a relatively complex structure and more parts, so the failure rate is relatively high. Compared with the normally closed solenoid valve, the working pressure of the normally open solenoid valve of the same specification is relatively lower. At the same time, the power of the coil also needs to be appropriately increased, especially for large-diameter normally open solenoid valves. Utility Model Content

[0005] 1. Technical issues to be solved

[0006] The utility model aims at the above defects existing in the prior art and proposes a large-caliber pilot-operated normally open solenoid valve to solve the problems that the existing normally open solenoid valve has a relatively complex structure, many parts and a relatively high failure rate.

[0007] 2. Technical Solution

[0008] In order to solve the above technical problems, the utility model provides a large-caliber pilot-operated normally open solenoid valve including:

[0009] Valve body;

[0010] A top cover arranged on the upper part of the valve body;

[0011] A bottom cover arranged at the lower part of the valve body;

[0012] A valve core assembly disposed inside the valve body;

[0013] A magnetic isolation tube arranged on the upper part of the top cover;

[0014] The left and right sides of the valve body are respectively provided with an inlet cavity, an outlet cavity, and a main valve port for connecting the inlet cavity and the outlet cavity, and the cavity between the upper part of the main valve port and the top cover is the main valve cavity;

[0015] The valve core assembly includes a piston, a valve stem, a connecting valve plate, a lower moving iron core, a connecting rod, and an iron core spring.

[0016] The lower moving iron core is sleeved in the connecting valve plate, the connecting rod is penetrated in the magnetic isolation tube, and the bottom of the connecting rod is sleeved with the upper part of the lower moving iron core, the two ends of the valve stem are respectively connected to the piston and the connecting valve plate, the connecting valve plate is used to close the main valve port, and the iron core spring is located between the connecting rod and the connecting valve plate;

[0017] A balance chamber is provided between the piston and the bottom cover, the main valve chamber and the balance chamber are arranged oppositely at the upper and lower sides of the valve body, and the piston is located between the balance chamber and the outlet chamber;

[0018] A normally open spring is arranged in the balance chamber, one end of the normally open spring abuts against the piston, and the other end of the normally open spring abuts against the inner wall of the bottom cover, and the normally open spring is used to keep the valve core assembly in a lifted state;

[0019] The large-caliber pilot-operated normally open electromagnetic valve also includes an electromagnetic drive device, and an upper moving iron core (5a) is also provided in the electromagnetic drive device. When the electromagnetic drive device is energized, the upper moving iron core (5a) can overcome the elastic force of the iron core spring (4h) and press downward, thereby driving the lower moving iron core (4c) to move through the connecting rod (4b);

[0020] The valve body also includes a piston chamber, which is used to accommodate and install the piston;

[0021] The main valve port and the piston cavity are coaxially arranged, and the piston cavity is connected to the outlet cavity;

[0022] The connecting valve plate is provided with a first through hole, and the valve stem is provided with a second through hole and a pilot valve port.

[0023] The fluid can enter the balance chamber through the first through hole, the pilot valve port and the second through hole in sequence.

[0024] The cross-sectional areas of the first through hole, the second through hole and the through hole of the pilot valve port are the same.

[0025] The piston is provided with a third through hole deviating from the piston axis, and the third through hole connects the balance chamber and the outlet chamber, and the through hole cross section area of ​​the third through hole is smaller than the cross section area of ​​the pilot valve port and the third through hole.

[0026] Among them, the outer diameter of the piston is equal to the outer diameter of the connecting valve plate. When the pilot valve port is opened, the pressure in the main valve chamber and the balance chamber is balanced. The piston and the connecting valve plate have the same pressure area, so the valve core assembly is also in a pressure balance state.

[0027] The valve core assembly, the piston chamber and the magnetic isolation tube are coaxially arranged.

[0028] Among them, a flange-shaped connecting end is provided at the upper end of the valve stem, and the valve stem is fixedly connected to the connecting valve plate through the flange-shaped connecting end. An annular valve port seal is provided near the edge of the connection between the valve stem and the connecting valve plate.

[0029] The outer ring edge of the flange-shaped connecting end presses the inner ring edge of the valve port seal. The valve port seal is used for sealing between the valve stem and the connecting valve plate, and is also used for sealing between the connecting valve plate and the main valve port.

[0030] The connecting valve plate includes a first connecting portion which is in a sleeve shape and has an opening at the top, and a second connecting portion which cooperates with a flange-shaped connecting end;

[0031] The lower moving iron core is penetrated on the first connecting part, and the first through hole is opened on the side wall of the first connecting part.

[0032] Wherein, an annular groove for arranging an annular valve port sealing member is provided at the bottom of the connecting valve plate.

[0033] 3. Beneficial Effects

[0034] Compared with the prior art, the solenoid valve of the utility model has a reasonable structure and has the following advantages. First, the coil is not energized in the original state, and the fluid enters the main valve chamber. Under the action of the iron core spring, the pilot valve port is in an open state, and the fluid enters the balance chamber. Since the third through hole is smaller than the pilot valve port, the pressure in the balance chamber quickly reaches equilibrium with the pressure in the main valve chamber. Since the cross-sectional area of ​​the piston and the connecting valve plate is the same, the upper and lower forces of the entire valve core assembly are balanced. Under the action of the normally open spring, the valve core assembly is always kept in a lifted state, so that when the solenoid valve is not energized, the solenoid valve is always normally open, and there is no need to energize the coil for a long time, thereby avoiding the coil being burned out due to long-term energization of the coil.

[0035] When the coil is energized, the upper moving iron core presses the lower moving iron core under the action of electromagnetic force, first closing the pilot valve port, and then under the action of pressure difference, the valve core assembly moves down to close the main valve port. Since the cross-section of the pilot valve port is much smaller than the main valve port, the electromagnetic force required to close the pilot valve port is very small, so the power of the coil can be smaller, the structure is simple, the failure rate is low, the reliability is high, the use pressure is high, and the coil power is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a main structural cross-section diagram of a large-caliber pilot-operated normally open solenoid valve.

[0037] Figure 2 It is a structural cross-sectional view of a large-caliber pilot-operated normally open solenoid valve core assembly.

[0038] Figure 3 It is a cross-sectional view of the valve body of a large-caliber pilot-operated normally open solenoid valve.

[0039] Figure 4 It is a partial cross-sectional view of the pilot part of a large-caliber pilot-operated normally open solenoid valve.

[0040] Figure 5 It is a large-caliber pilot-operated normally open solenoid valve, which is a front view structural cross-section diagram when it is normally open during operation.

[0041] Figure 6 It is a schematic diagram of the working principle structure of a large-caliber pilot-operated normally open solenoid valve after power is supplied.

[0042] In the figure:

[0043] 1 is a valve body;

[0044] 1a is the inlet cavity; 1b is the outlet cavity; 1c is the main valve port; 1d is the piston cavity; 1e is the inlet thread; 1f is the outlet thread; 11 is the main valve cavity; 13 is the balance cavity;

[0045] 2 is the top cover;

[0046] 3 is the bottom cover;

[0047] 4 is a valve core assembly; 4a is a piston; 41a is a third through hole; 4b is a connecting rod; 4c is a lower moving iron core; 41c is an iron core seal; 4d is a valve stem; 41d is a second through hole; 42d is a pilot valve port; 43d is a flange-shaped connecting end; 4e is a connecting valve plate; 41e is a first through hole; 42e is a first connecting portion; 43e is a second connecting portion; 4f is a valve port seal; 4h is an iron core spring;

[0048] 5 is a magnetic isolation tube; 5a is an upper moving iron core;

[0049] 6 is a coil;

[0050] 7 is a normally open spring. DETAILED DESCRIPTION

[0051] The following is a further detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0052] Embodiment 1:

[0053] like Figure 1 to Figure 6 As shown, a large-caliber pilot-operated normally open solenoid valve of this embodiment comprises: a valve body 1; a top cover 2 arranged on the upper part of the valve body 1; a bottom cover 3 arranged on the lower part of the valve body 1; a valve core assembly 4 arranged inside the valve body 1; a magnetic isolation tube 5 arranged on the upper part of the top cover 2;

[0054] For example, the left and right sides of the valve body 1 are respectively provided with an inlet cavity 1a, an outlet cavity 1b, and a main valve port 1c for connecting the inlet cavity 1a and the outlet cavity 1b, and the cavity between the upper part of the main valve port 1c and the top cover 2 is the main valve cavity 11; the valve core assembly 4 includes a piston 4a, a valve stem 4d, a connecting valve plate 4e, a lower moving iron core 4c, a connecting rod 4b, and an iron core spring 4h, the lower moving iron core 4c is sleeved in the connecting valve plate 4e, the connecting rod 4b is penetrated and arranged in the magnetic isolation tube 5, and the bottom of the connecting rod 4b is sleeved with the upper part of the lower moving iron core 4c, the two ends of the valve stem 4d are respectively connected to the piston 4a and the connecting valve plate 4e, the connecting valve plate 4e is used for closing the main valve port 1c, and the iron core spring 4h is located between the connecting rod 4b and the connecting valve plate 4e;

[0055] For example, a balancing chamber 13 is provided between the piston 4a and the bottom cover 3, the main valve chamber 11 and the balancing chamber 13 are arranged oppositely at the upper and lower sides of the valve body 1, and the piston 4a is located between the balancing chamber 13 and the outlet chamber 1b;

[0056] A normally open spring 7 is provided in the balance chamber 13, one end of the normally open spring 7 abuts against the piston 4a, and the other end of the normally open spring 7 abuts against the inner wall of the bottom cover 3. The normally open spring 7 is used to keep the valve core assembly 4 in a raised state.

[0057] The valve body 1 further comprises a piston chamber 1d, for example, the piston chamber 1d is used to accommodate and install the piston 4a; the main valve port 1c and the piston chamber 1d are coaxially arranged, and the piston chamber 1d is communicated with the outlet chamber 1b.

[0058] like Figure 2 and Figure 4As shown, the connecting valve plate 4e is provided with a first through hole 41e, and the valve stem 4d is provided with a pilot valve port 42d and a second through hole 41d. Specifically, the connecting valve plate 4e includes a sleeve-shaped first connecting portion 42e with an opening at the top, and a second connecting portion 43e matched with the flange-shaped connecting end 43d described below; the moving iron core 4c is penetrated on the first connecting portion 42e, and the first through hole 41e is opened on the side wall of the first connecting portion 42e. The main valve chamber 11 and the balance chamber 13 are controlled to be on and off by the first through hole 41e, the second through hole 41d and the pilot valve port 42d. When the pilot valve port 42d is opened, the main valve chamber 11 and the balance chamber 13 are connected. When the pilot valve port 42d is closed, the main valve chamber 11 and the balance chamber 13 are blocked.

[0059] The cross-sectional areas of the first through hole 41e, the second through hole 41d and the pilot valve port 42d are the same. Once the pilot valve port 42d is opened, the fluid in the main valve chamber 11 can smoothly and quickly enter the balance chamber 13 until the pressure in the main valve chamber 11 and the balance chamber 13 is balanced.

[0060] The piston 4a is provided with a third through hole 41a, through which the balance chamber 13 and the outlet chamber 1b are connected. The cross-sectional area of ​​the third through hole 41a is smaller than the cross-sectional area of ​​the pilot valve port 42d and the second through hole 41d. When the fluid of the main valve chamber 11 enters the balance chamber 13, the pressure of the balance chamber 13 is greater than the outlet chamber 1b. When the pilot valve port 42d is closed, the pressure of the balance chamber 13 is released through the third through hole 41a until the pressure of the balance chamber 13 is the same as the pressure of the outlet chamber 1b. At this time, the pressure of the balance chamber 13 is lower than the pressure of the main valve chamber 11.

[0061] The outer diameter of the piston 4a is the same as the maximum outer diameter of the connecting valve plate 4e. When the pilot valve port 42d is opened, the pressure of the main valve chamber 11 and the balance chamber 13 are balanced. Since the outer diameters are the same, the valve core assembly 4 is in a pressure balance state at this time. The valve core assembly 4 is only subjected to the elastic force of the normally open spring 7, and the valve core assembly 4 is lifted upward as a whole. At this time, the main valve port 1c is opened, and the solenoid valve is in a normally open state.

[0062] The connecting rod 4b and the lower moving iron core 4c are connected by screw thread fixation. An iron core spring 4h is arranged between the connecting rod 4b and the connecting valve plate 4e to connect the lower moving iron core 4c and the connecting valve plate 4e. An iron core seal 41c is arranged at the bottom of the lower moving iron core 4c to dynamically seal the pilot valve port 42d. When the coil 6 is not energized, under the action of the iron core spring 4h, the lower moving iron core 4c is lifted upward, and the pilot valve port 42d remains open. When the coil 6 is energized, the upper moving iron core 5a overcomes the elastic force of the iron core spring 4h and is pressed downward, and the iron core seal 41c closes the pilot valve port.

[0063] The valve core assembly 4, piston chamber 1d and magnetic isolation tube 5 are on the same axis. The valve stem 4d and piston 4a play an up and down guiding role, ensuring that the valve core assembly 4 can only move up and down. Due to the guidance, the impact and deviation of the valve core assembly 4 caused by fluid pressure is avoided, thereby ensuring that the valve core assembly 4 can move up and down reliably.

[0064] When the coil 6 is energized, under the action of electromagnetic force, the upper moving iron core 5a presses down the moving iron core 4c, first closing the pilot valve port 42d, and then under the action of pressure difference, the valve core assembly 4 moves down to close the main valve port 1c. Since the cross section of the pilot valve port 42d is much smaller than the main valve port 1c, the electromagnetic force required to close the pilot valve port 42d is very small, so the power of the coil 6 can be smaller, so that a small-power coil closes a large-diameter electromagnetic valve. When the coil 6 is de-energized, under the action of the iron core spring 4h, the pilot valve port 42d opens first, so that the pressure of the upper and lower cross sections of the valve core assembly 4 is balanced. The opening of the main valve port 1 only requires the elastic force of the normally open spring 7. Therefore, by adjusting the elastic force of the normally open spring 7, the electromagnetic valve can be opened at a higher pressure.

[0065] In this embodiment, the size range of the main valve port 1c is DN5 mm-100 mmDN: nominal diameter, and the connection methods include but are not limited to the inlet thread 1e and the outlet thread 1f, and can also be other thread connection methods or flanges and other connection methods. The structure of the coil 6 includes but is not limited to the structure shown in the figure, and the coil voltage includes various direct currents and alternating currents.

[0066] The utility model provides a large-caliber pilot-operated normally open electromagnetic valve. When the coil is powered off, the electromagnetic valve is in a normally open state. When the coil is powered on, the electromagnetic valve is closed. Therefore, the original state of the electromagnetic valve is normally open. The working principle of the utility model is further described in conjunction with the accompanying drawings: in the original state of the solenoid valve, the coil 6 is not energized, and the fluid enters the main valve chamber 11. Under the action of the iron core spring 4h, the pilot valve port 42d is in an open state, and the fluid enters the balance chamber 13 through the first through hole 41e, the pilot valve port 42d, and the second through hole 41d respectively. Since the third through hole 41a is smaller than the pilot valve port 42d, the pressure in the balance chamber 13 quickly reaches equilibrium with the pressure in the main valve chamber 11. Since the cross-sectional area of ​​the piston 4a and the connecting valve plate 4e is the same, the upper and lower forces of the entire valve core assembly 4 are balanced. Under the action of the normally open spring 7, the valve core assembly 4 is always kept in a lifted state. At this time, the main valve port 1c is also kept in an open state, and the fluid continues to flow out from the outlet chamber 1b through the main valve port 1c. At this time, the solenoid valve is in a normally open state.

[0067] When the coil 6 is energized, under the action of electromagnetic force, the upper moving iron core 5a presses down the valve stem 4d, driving the lower moving iron core 4c to close the pilot valve port 42d. At this time, the fluid in the main valve chamber 11 cannot flow to the balance chamber 13, and the pressure of the balance chamber 13 keeps releasing pressure toward the outlet chamber 1b until it is consistent with the pressure of the outlet chamber 1b. At this time, the pressure on the valve core assembly 4 is greater than the pressure at the bottom. Under the action of the pressure difference, the valve core assembly 4 moves downward to close the main valve port 1c, and the solenoid valve is in a closed state at this time.

[0068] When the coil 6 is powered off again, the pilot valve port 42d opens, the pressure in the balance chamber 13 is balanced with the pressure in the main valve chamber 11 again, and under the action of the normally open spring 7, the valve core assembly 4 is lifted up again, the main valve port 1c opens, and the solenoid valve returns to the normally open state.

[0069] The electromagnetic force of the coil 6 of the utility model first controls the opening and closing of the pilot valve port 42d, and then controls the opening and closing of the main valve port 1c. When the coil 6 is powered off, the pilot valve port 42d is opened and the main valve port 1c is also opened. When the coil 6 is powered on, the pilot valve port 42d is closed and the main valve port is also opened and closed.

[0070] Embodiment 2:

[0071] Compared with the first embodiment, in the present embodiment, a flange-shaped connecting end 43d is provided at the upper end of the valve stem 4d, and the valve stem 4d is fixedly connected to the connecting valve plate 4e through the flange-shaped connecting end 43d, and an annular valve port sealing member 4f is provided near the edge of the connection between the valve stem 4d and the connecting valve plate 4e.

[0072] The outer edge of the flange-shaped connecting end 43d presses the inner edge of the valve port seal 4f, and the valve port seal 4f is used for sealing between the valve stem 4d and the connecting valve plate 4e, and is also used for sealing between the connecting valve plate 4e and the main valve port 1c, which has a double sealing effect, and the valve port seal 4f can be fixed more effectively through this structural design. An annular groove for arranging the annular valve port seal 4f is provided at the bottom of the connecting valve plate 4e.

[0073] The above are only preferred implementations of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A large-caliber pilot-operated normally open solenoid valve, characterized in that: The large-caliber pilot-operated normally open solenoid valve comprises: Valve body (1); A top cover (2) arranged on the upper part of the valve body (1); A bottom cover (3) arranged at the lower part of the valve body (1); A valve core assembly (4) disposed inside the valve body (1); A magnetic isolation tube (5) arranged on the upper part of the top cover (2); The valve body (1) is provided with an inlet cavity (1a), an outlet cavity (1b), and a main valve port (1c) for connecting the inlet cavity (1a) and the outlet cavity (1b) on the left and right sides respectively; the cavity between the upper part of the main valve port (1c) and the top cover (2) is the main valve cavity (11); The valve core assembly (4) comprises a piston (4a), a valve stem (4d), a connecting valve plate (4e), a lower moving iron core (4c), a connecting rod (4b), and an iron core spring (4h). The lower moving iron core (4c) is sleeved in the connecting valve plate (4e), the connecting rod (4b) is arranged through the magnetic isolation tube (5), and the bottom of the connecting rod (4b) is sleeved with the upper part of the lower moving iron core (4c), the two ends of the valve stem (4d) are respectively connected to the piston (4a) and the connecting valve plate (4e), the connecting valve plate (4e) is used to close the main valve port (1c), and the iron core spring (4h) is located between the connecting rod (4b) and the connecting valve plate (4e); A balancing chamber (13) is provided between the piston (4a) and the bottom cover (3); the main valve chamber (11) and the balancing chamber (13) are arranged oppositely at upper and lower sides of the valve body (1); and the piston (4a) is located between the balancing chamber (13) and the outlet chamber (1b); A normally open spring (7) is provided in the balance chamber (13), one end of the normally open spring (7) abuts against the piston (4a), and the other end of the normally open spring (7) abuts against the inner wall of the bottom cover (3), and the normally open spring (7) is used to keep the valve core assembly (4) in a raised state; The large-caliber pilot-operated normally open electromagnetic valve also includes an electromagnetic drive device, and an upper moving iron core (5a) is also provided in the electromagnetic drive device. When the electromagnetic drive device is energized, the upper moving iron core (5a) can overcome the elastic force of the iron core spring (4h) and press downward, thereby driving the lower moving iron core (4c) to move through the connecting rod (4b); The valve body (1) further comprises a piston chamber (1d), wherein the piston chamber (1d) is used to accommodate and install a piston (4a); The main valve port (1c) and the piston chamber (1d) are coaxially arranged, and the piston chamber (1d) and the outlet chamber (1b) are in communication; The connecting valve plate (4e) is provided with a first through hole (41e), and the valve stem (4d) is provided with a second through hole (41d) and a pilot valve port (42d). The fluid can enter the balance chamber (13) through the first through hole (41e), the pilot valve port (42d) and the second through hole (41d) in sequence.

2. A large-caliber pilot-operated normally open solenoid valve according to claim 1, characterized in that: The first through hole (41e), the second through hole (41d) and the pilot valve port (42d) have the same through hole cross-section area.

3. A large-caliber pilot-operated normally open solenoid valve according to claim 1, characterized in that: The piston (4a) is provided with a third through hole (41a) deviating from the axis of the piston (4a), and the third through hole (41a) is connected with the balance chamber (13) and the outlet chamber (1b), and the area of ​​the through hole cross section of the third through hole (41a) is smaller than the area of ​​the cross section of the pilot valve port (42d) and the third through hole (41a).

4. A large-caliber pilot-operated normally open solenoid valve according to claim 1, characterized in that: The outer diameter of the piston (4a) is equal to the outer diameter of the connecting valve plate (4e). When the pilot valve port (42d) is opened, the pressures in the main valve chamber (11) and the balance chamber (13) are balanced. The piston (4a) and the connecting valve plate (4e) have the same pressure area, so that the valve core assembly (4) is also in a pressure balanced state.

5. A large-caliber pilot-operated normally open solenoid valve according to claim 1, characterized in that: The valve core assembly (4), the piston chamber (1d) and the magnetic isolation tube (5) are coaxially arranged.

6. A large-caliber pilot-operated normally open solenoid valve according to claim 1, characterized in that: The upper end of the valve stem (4d) is provided with a flange-shaped connecting end (43d), the valve stem (4d) is fixedly connected to the connecting valve plate (4e) via the flange-shaped connecting end (43d), and an annular valve port sealing member (4f) is provided near the edge of the connection between the valve stem (4d) and the connecting valve plate (4e). The outer edge of the flange-shaped connecting end (43d) presses the inner edge of the valve port seal (4f). The valve port seal (4f) is used for sealing between the valve stem (4d) and the connecting valve plate (4e), and is also used for sealing between the connecting valve plate (4e) and the main valve port (1c).

7. A large-caliber pilot-operated normally open solenoid valve according to claim 2, characterized in that: The connecting valve plate (4e) comprises a first connecting portion (42e) which is in a sleeve shape and has an opening at the top, and a second connecting portion (43e) which cooperates with a flange-shaped connecting end (43d); The lower moving iron core (4c) is inserted into the first connecting portion (42e), and the first through hole (41e) is formed on a side wall of the first connecting portion (42e).

8. A large-caliber pilot-operated normally open solenoid valve according to claim 6, characterized in that: An annular groove for arranging an annular valve port sealing member (4f) is provided at the bottom of the connecting valve plate (4e).

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