Pilot-operated type backpressure switching valve

Abstract

The utility model relates to the technical field of valve bodies, in particular to a pilot-operated type backpressure switching valve which comprises a main valve assembly, a pilot-operated valve assembly and a connector assembly, the pilot-operated valve assembly and the connector assembly are located at the front end of the main valve assembly, the connector assembly is used for supplying power to the pilot-operated valve assembly, and the pilot-operated valve assembly is used for controlling the main valve assembly to work according to power-on and power-off states. The main valve assembly comprises a front cover, a rear cover, a valve body, a valve rod, a first piston, a second piston, a spacer bush and a reset spring, the front cover is located between the front end of the valve body and the pilot valve assembly, the rear cover is arranged at the rear end of the valve body, the valve rod is arranged in the valve body, the first piston abuts against the position between the end of the valve rod and the front cover, and one end of the second piston abuts against the valve rod. The spacer bush is assembled between the valve body and the rear cover and arranged outside the second piston in a sleeving mode, the reset spring is located in the spacer bush, and the two ends of the reset spring abut against the rear cover and the other end face of the second piston respectively. Two output modes with back pressure and without back pressure can be achieved, various expected function requirements are met, the use cost is low, and installation is convenient.

Description

Technical Field

[0001] This utility model relates to the field of valve body technology, and in particular to a pilot-operated back pressure switching valve. Background Technology

[0002] In the handling of heavy production machinery or tools, in order to reduce reliance on manpower and reduce labor costs, mechanical systems are usually used to output force, such as using cylinders to drive the load and using valves to control the movement of the cylinders. In terms of functionality, the system must ensure that the load can move in a straight line and can be safely and stably stopped at any position. When the cylinder drives the load, the speed must be controlled to avoid causing safety accidents due to excessive speed.

[0003] In related technologies, the commonly used technical solution is as follows: a low-friction cylinder is arranged downwards and connected to the load. A precision pressure reducing valve and a two-position, three-normally closed, spring-returned solenoid valve are connected to the rear end of the cylinder, and a precision pressure reducing valve and a two-position, three-normally closed, spring-returned solenoid valve are connected to the front end of the cylinder. When the two-position, three-normally closed valves at the front and rear ends are opened, due to the difference in piston cross-sectional area, the force at the rear end is greater than the force at the front end, and the cylinder piston rod extends slowly, achieving the effect of slow load reduction. When the load reaches the ideal position, the solenoid valve connected to the rear end of the cylinder closes, while the solenoid valve connected to the front end remains in a venting state. By adjusting the pressure of the precision pressure reducing valve, the force acting on the piston is balanced with the gravity of the load, allowing the load to remain stationary at any position. At this point, the spatial position of the load can be freely adjusted. The above method uses multiple valves to form a pneumatic circuit, which requires high costs. Furthermore, the pressure of the precision pressure reducing valve needs to be adjusted during use to control the load balance, resulting in complex wiring and operation, and high maintenance difficulty.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background technology of this utility model, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a pilot-operated back pressure switching valve to simplify and individually control the load air circuit, thereby reducing the cost of use and the difficulty of installation and maintenance.

[0006] To achieve the above objectives, the technical solution adopted by this utility model is: a pilot-operated back pressure switching valve, comprising: a main valve assembly and a pilot valve assembly and a connector assembly located at the front end of the main valve assembly, wherein the connector assembly is used to supply power to the pilot valve assembly, and the pilot valve assembly is used to control the operation of the main valve assembly according to the power supply status;

[0007] The main valve assembly includes a front cover, a rear cover, a valve body, a valve stem, a first piston, a second piston, a spacer, and a return spring. The front cover is located between the front end of the valve body and the pilot valve assembly. The rear cover is located at the rear end of the valve body. The valve stem is built into the valve body. The first piston is abutted between the end of the valve stem and the front cover. One end of the second piston abuts against the valve stem. The spacer is fitted between the valve body and the rear cover and is sleeved on the outside of the second piston. The return spring is located in the spacer, with both ends abutting against the other end faces of the rear cover and the second piston, respectively.

[0008] Furthermore, sealing gaskets are provided between the front cover and the front end of the valve body, and between the rear cover and the rear end of the valve body.

[0009] Furthermore, the valve body is provided with a first working air pressure output port and a second working air pressure output port. Both the first working air pressure output port and the second working air pressure output port are connected to the assembly space where the valve stem is located. The first working air pressure output port is connected to the air inlet of the rear cover of the cylinder, and the second working air pressure output port is connected to the air inlet of the front cover of the cylinder.

[0010] Furthermore, the valve body is provided with three external air source inlets, and each of the three external air source inlets is connected to a pressure reducing valve.

[0011] Furthermore, a main exhaust port is provided on the valve body, and the main exhaust port is connected to the first working air pressure output port.

[0012] Furthermore, sealing gaskets are provided at the first working air pressure output port, the second working air pressure output port, the three external air source vents, the main exhaust port, and the junction of the valve stem and the valve body.

[0013] Furthermore, the pilot valve assembly includes a coil assembly, a first rubber plug, a push rod, a second rubber plug, a moving iron core, and a valve seat. The moving iron core is slidably disposed in the coil assembly, the second rubber plug is disposed inside the moving iron core, one end of the moving iron core abuts against the push rod, the push rod and the first rubber plug are disposed in the valve seat, and the first rubber plug is located at the other end of the push rod.

[0014] Furthermore, the valve seat is provided with a pilot valve exhaust port and a pilot valve working port, the pilot valve exhaust port being configured corresponding to the first rubber plug, and the pilot valve working port being configured corresponding to the second rubber plug.

[0015] Furthermore, a pilot air port is provided on the front cover, the pilot air port is located on the outer side of the front cover and communicates with the interior of the valve seat.

[0016] Furthermore, a pilot air intake passage and a pilot exhaust passage are provided on the side of the front cover facing the pilot valve assembly. The pilot air intake passage is connected to the pilot valve working port, and the pilot exhaust passage is connected to the pilot valve exhaust port.

[0017] The beneficial effects of this utility model are as follows: This utility model uses a back pressure switching valve with a high degree of functional integration. Only one control element is needed to realize two different outputs in the pneumatic control system to control the action of the cylinder. In use, only the on and off state of the pilot valve assembly needs to be controlled through the connector assembly to easily realize the two output modes with and without back pressure, thereby meeting a variety of expected functional requirements. It can also be wired and controlled independently, with extremely low operating costs and very convenient installation. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the pilot-operated back pressure switching valve in an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of the assembly of the pilot-operated back pressure switching valve in an embodiment of this utility model;

[0021] Figure 3 This is a front view of the pilot-operated back pressure switching valve in an embodiment of this utility model;

[0022] Figure 4 This is a cross-sectional view of the main valve assembly AA when back pressure is output;

[0023] Figure 5 This is a cross-sectional view of the main valve assembly AA when the load is balanced.

[0024] Figure 6 This is a side view of the pilot-operated back pressure switching valve in an embodiment of the present invention;

[0025] Figure 7 for Figure 6 Sectional view at point BB;

[0026] Figure 8 This is a rear view of the pilot-operated back pressure switching valve in an embodiment of the present invention.

[0027] Figure 9 for Figure 8 Sectional view at CC;

[0028] Figure 10 This is a schematic diagram of the front cover in an embodiment of the present utility model.

[0029] Reference numerals: 10. Main valve assembly; 11. Front cover; 11a. Pilot air port; 11b. Pilot air inlet; 11c. Pilot exhaust port; 12. Rear cover; 13. Valve body; 13a. First working air pressure output port; 13b. Second working air pressure output port; 13c. External air source vent; 13d. Main exhaust port; 14. Valve stem; 15. First piston; 16. Second piston; 17. Spacer; 18. Return spring; 19. Sealing gasket; 20. Pilot valve assembly; 21. Coil assembly; 22. First rubber plug; 23. Push rod; 24. Second rubber plug; 25. Moving iron core; 26. Valve seat; 26a. Pilot valve exhaust port; 26b. Pilot valve working port; 30. Connector assembly. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0031] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] like Figures 1 to 10 The pilot-operated back pressure switching valve shown includes: a main valve assembly 10, a pilot valve assembly 20 and a connector assembly 30 located at the front end of the main valve assembly 10, the connector assembly 30 being used to supply power to the pilot valve assembly 20, and the pilot valve assembly 20 being used to control the operation of the main valve assembly 10 according to the power supply status.

[0034] The main valve assembly 10 includes a front cover 11, a rear cover 12, a valve body 13, a valve stem 14, a first piston 15, a second piston 16, a spacer 17, and a return spring 18. The front cover 11 is located between the front end of the valve body 13 and the pilot valve assembly 20. The rear cover 12 is located at the rear end of the valve body 13. The valve stem 14 is built into the valve body 13. The first piston 15 is abutted between the end of the valve stem 14 and the front cover 11. One end of the second piston 16 abuts against the valve stem 14. The spacer 17 is assembled between the valve body 13 and the rear cover 12 and is sleeved on the outside of the second piston 16. The return spring 18 is located in the spacer 17, and its two ends abut against the other end faces of the rear cover 12 and the second piston 16, respectively.

[0035] This utility model uses a highly integrated back pressure switching valve, which requires only one control element to achieve two different outputs in the pneumatic control system to control the cylinder's movement. In use, only the on / off state of the pilot valve assembly 20 needs to be controlled through the connector assembly 30 to easily achieve the two output modes with and without back pressure, thereby meeting a variety of expected functional requirements. It can also be wired and controlled independently, with extremely low operating costs and very convenient installation.

[0036] Specifically, the front cover 11 is located at the front end of the valve body 13, serving to connect with the pilot valve assembly 20, and also providing certain limiting and sealing functions for internal components such as the valve stem 14 and piston. The front cover 11 also has two air passages, used to supply air from the main air inlet of the valve body 13 to the air inlet of the pilot valve assembly 20 and to connect the pilot valve working port 26b to the first piston 15. The rear cover 12 is located at the rear end of the valve body 13, providing support and positioning for components such as the valve stem 14 and the second piston 16, ensuring the structural stability of the entire main valve assembly 10.

[0037] The valve body 13 serves as the main carrier of the main valve assembly 10, providing installation space and movement channels for components such as the valve stem 14, the first piston 15, and the second piston 16, ensuring that the gas can flow along a predetermined path inside, thus enabling the cylinder to operate normally. The valve stem 14 connects the first piston 15 and the second piston 16 and moves axially under the action of gas pressure. Under the action of the return spring 18, the valve stem 14 is reset to its initial state. The movement of the valve stem 14 controls the on / off state and flow rate of the gas, thereby controlling the extension and retraction of the cylinder piston rod and the output force of the cylinder, thus achieving load motion control.

[0038] The first piston 15 and the second piston 16 generate thrust under the action of gas pressure, and different force balance states can be achieved through the difference in piston area, thereby controlling the movement direction and speed of the cylinder. When the pilot valve assembly 20 is energized, it can change the way the gas acts on the first piston 15 and the second piston 16, causing the valve stem 14 to move, thereby changing the intake and exhaust of the cylinder and controlling the rise or fall of the load.

[0039] Specifically, the first piston 15 is propelled by airflow through the process hole on the valve body 13 of the main valve assembly 10, then through the air passage on the front cover 11 to the pilot valve assembly 20. When the pilot valve assembly 20 is energized, its working port outputs airflow through another air passage on the front cover 11 to the first piston 15, thus propelling it to move. The second piston 16 is continuously pressurized by airflow through another process hole on the valve body 13 of the main valve assembly 10, then through an air passage on the rear cover 12. In addition, the return spring 18 also applies a force to the second piston 16. These two forces allow the valve stem 14 to return to its initial position when the first piston 15 is not under force. Even in the event of an air passage failure, the return spring 18 is sufficient to return the valve stem 14 to its initial position, ensuring safety. The valve stem 14 in two different positions within the valve body allows the two working ports 12a and 13b to produce different outputs, thereby controlling the cylinder to drive the load to the expected tooling state.

[0040] The spacer 17 guides the second piston 16 and the return spring 18, ensuring that the second piston 16 can move smoothly along the axial direction during the movement, avoiding the tilting and jamming of the second piston 16. At the same time, the spacer 17 also helps to seal and prevent gas leakage. The return spring 18 can restore the main valve assembly 10 to its initial state when the pilot valve assembly 20 is de-energized or there is no external control signal.

[0041] Furthermore, the back pressure switching valve of this utility model has many application scenarios, occupies little space, and can be widely used in heavy equipment operation scenarios to improve work efficiency; it also has a simple structure and extremely low processing cost; assembly and operation are simple, and it can be quickly replaced in case of failure.

[0042] Based on the above embodiments, sealing gaskets 19 are provided between the front end of the front cover 11 and the front end of the valve body 13, and between the rear end of the rear cover 12 and the rear end of the valve body 13. When combined with the special shape and structure on the front cover 11 and the rear cover 12 to form an internal air passage, they can effectively prevent gas from leaking from the connection points, ensure the stability of the pressure inside the cylinder, avoid accidental movement of the load position due to gas leakage, and improve the safety and stability of the system. In addition, the sealing gaskets 19 have a certain degree of elasticity and flexibility, which can play a buffering role between the front cover 11 and the valve body 13, and between the rear cover 12 and the valve body 13, reducing the impact of mechanical vibration and impact on the precision components inside the valve body 13, extending the service life of the main valve assembly 10, reducing the risk of component damage due to vibration and impact, and improving the reliability of the system.

[0043] Based on the above embodiments, the valve body 13 is provided with a first working air pressure output port 13a and a second working air pressure output port 13b. Both the first working air pressure output port 13a and the second working air pressure output port 13b are connected to the assembly space where the valve stem 14 is located. The first working air pressure output port 13a is connected to the air inlet of the rear cover 12 of the cylinder, and the second working air pressure output port 13b is connected to the air inlet of the front cover 11 of the cylinder. By controlling the air pressure of the first working air pressure output port 13a and the second working air pressure output port 13b, precise control of the movement of the cylinder piston rod can be achieved. Moreover, since both the first working air pressure output port 13a and the second working air pressure output port 13b are connected to the assembly space where the valve stem 14 is located, the air circuit is effectively integrated inside the valve body 13, reducing the complexity of external air circuit connections and facilitating installation and maintenance.

[0044] In practical applications, the two pneumatic output ports of this back pressure switching valve are connected to the front and rear ends of the loaded cylinder, respectively, to output pressure. The cylinder can then move slowly under back pressure, effectively avoiding safety hazards and equipment damage caused by excessive speed. When only one pneumatic output port is used to output pressure to one end of the cylinder, an external precision pressure reducing valve or proportional pressure valve can be connected to precisely set the pressure value, ensuring that the force output by the actuator cylinder is balanced with the load's weight. This allows operators to more easily and flexibly control the spatial position of the load, precisely controlling its position when moving heavy machinery, reducing manpower consumption and operational difficulty.

[0045] Based on the above embodiment, the valve body 13 is provided with three external air source inlets 13c, which are respectively connected to pressure reducing valves. The three external air source inlets 13c are connected to external air pressure, namely P1, P2, and P3. During operation, the front end of the external air source inlet 13c of P2 needs to be connected to a precision pressure reducing valve or a proportional pressure valve, while the front ends of the external air source inlets 13c of P1 and P3 can be connected to ordinary pressure reducing valves. The first working air pressure output port 13a is connected to the air inlet of the rear cover 12 of the low friction cylinder, and the second working air pressure output port 13b is connected to the air inlet of the front cover 11 of the cylinder.

[0046] Based on the above embodiments, a main exhaust port 13d is opened on the valve body 13. The main exhaust port 13d is connected to the first working air pressure output port 13a, so that the gas in the cylinder rear cover 12 part can be smoothly discharged during the piston rod movement, balance the air pressure and control the movement speed, simplify the air circuit system and reduce the maintenance difficulty, and improve the safety and reliability of the system.

[0047] Based on the above embodiments, sealing gaskets 19 are provided at the first working air pressure output port 13a, the second working air pressure output port 13b, the three external air source vents 13c, the main exhaust port 13d, and the junction of the valve stem 14 and the valve body 13; this enhances the sealing performance of each key part, prevents gas leakage, ensures stable air pressure in the cylinder system, and guarantees the stability of the air circuit connection, thereby improving the operating efficiency and reliability of the entire system.

[0048] Based on the above embodiments, the pilot valve assembly 20 includes a coil assembly 21, a first rubber plug 22, a push rod 23, a second rubber plug 24, a moving iron core 25, and a valve seat 26. The coil assembly 21 consists of a coil, a magnetic shielding tube, and a stationary iron core. The moving iron core 25 is slidably disposed in the magnetic shielding tube of the coil assembly 21. When the coil is energized, the stationary iron core generates a magnetic field that attracts the moving iron core. The second rubber plug 24 is disposed inside the moving iron core 25. One end of the moving iron core 25 abuts against the push rod 23, and the other end is connected to a spring. The spring force supports the moving iron core 25 so that the second rubber plug 24 contacts and seals with the pilot valve working port 26b of the valve seat 26. At the same time, the push rod 23 is also pushed up by the moving iron core 25. The push rod 23 and the first rubber plug 22 are disposed in the valve seat 26. The first rubber plug 22 is located at the other end of the push rod 23, and a spring is placed on top of it. Finally, it is tightly connected to the push rod 23 as one unit. When the moving iron core 25 is attracted, the pilot valve working port 26b of the valve seat 26 is opened, and the push rod 23, which was lifted by the attraction, falls down. The spring force causes the first rubber plug 22 to contact and seal with the pilot valve exhaust port 26a of the valve seat 26. Through the sliding of the moving iron core 25 in the coil assembly 21 and the cooperation with the push rod 23, rubber plug and other components, the pilot valve assembly 20 can accurately control the working state of the main valve assembly 10 according to the energized or de-energized state, thereby realizing precise control of the cylinder load movement, including the rise and fall of the load and stable stopping at any position. Moreover, the pilot valve assembly 20 is a relatively independent module, which is convenient for integrated installation with the main valve assembly 10. It is also convenient for quick disassembly and repair in case of failure, reducing maintenance costs and downtime.

[0049] Specifically, the valve seat 26 serves as the basic support structure of the pilot valve assembly 20, providing space for the installation and movement of other components such as the moving iron core 25 and the push rod 23, ensuring the accuracy of the relative positions and movement trajectories of each component. The first rubber plug 22 is located at the other end of the push rod 23, serving a sealing and limiting function. On the one hand, it prevents gas leakage from the gap between the push rod 23 and the valve seat 26, ensuring stable internal air pressure in the pilot valve assembly 20. On the other hand, it limits the range of motion of the push rod 23, preventing excessive movement that could damage or cause loss of control. The push rod 23 serves as the connecting component between the moving iron core 25 and the first rubber plug 22, transmitting the movement of the moving iron core 25 to the first rubber plug 22, thereby indirectly affecting the air circuit opening and closing state of the main valve assembly 10. The second rubber plug 24 can reduce the mechanical impact between the moving iron core 25 and the push rod 23, extending the component's lifespan, while also preventing gas leakage from the gap between the moving iron core 25 and the coil assembly 21, ensuring air pressure balance inside the pilot valve assembly 20.

[0050] When the pilot valve assembly 20 is energized, the moving iron core 25 slides under the action of electromagnetic force, overcoming the spring force and other forces, driving the push rod 23 and other components to move, thereby changing the air path state of the main valve assembly 10; when de-energized, the moving iron core 25 resets under the action of spring force and other forces, restoring the initial state of the main valve assembly 10.

[0051] Based on the above embodiments, the valve seat 26 is provided with a pilot valve exhaust port 26a and a pilot valve working port 26b. The pilot valve exhaust port 26a is correspondingly set with the first rubber plug 22, and the pilot valve working port 26b is correspondingly set with the second rubber plug 24. This enables precise control of the gas inlet and outlet, making the sliding of the moving iron core 25 smoother and more stable, thereby improving the accuracy and response speed of the pilot valve assembly 20 in controlling the main valve assembly 10, and improving the stability and safety of the system.

[0052] Based on the above embodiments, a pilot air port 11a is provided on the front cover 11. The pilot air port 11a is located on the outer side of the front cover 11 and communicates with the inside of the valve seat 26. Pilot air enters from the pilot air port 11a at the position of the front cover 11, and is guided into the valve seat 26 of the pilot valve through the flow channel, providing an independent and stable air supply channel for the pilot valve assembly 20, simplifying the air path layout and improving system integration.

[0053] Based on the above embodiment, a pilot air intake passage 11b and a pilot exhaust passage 11c are provided on the side of the front cover 11 facing the pilot valve assembly 20. The pilot air intake passage 11b is connected to the pilot valve working port 26b, and the pilot exhaust passage 11c is connected to the pilot valve exhaust port 26a. The pilot exhaust passage 11b controls the gas from the pilot valve assembly 20 to enter the main valve assembly 10 and controls the gas from the main valve assembly 10 to be discharged.

[0054] In this embodiment, the back pressure switching valve has two working states: an output mode without back pressure and an output mode with back pressure. When the pilot valve assembly 20 is energized, it is in the output mode without back pressure to balance the load. When the pilot valve assembly 20 is de-energized, it is in the output mode with back pressure to realize the cylinder action under the condition of back pressure.

[0055] During use, the three external air supply ports 13c of the back pressure switching valve are connected to external air pressure, namely P1, P2, and P3. Among them, the front end of the external air supply port 13c of P2 needs to be connected to a precision pressure reducing valve or a proportional pressure valve, while the front ends of the external air supply ports 13c of P1 and P3 can be connected to ordinary pressure reducing valves. The first working air pressure output port 13a is connected to the air inlet of the rear cover 12 of the low friction cylinder, and the second working air pressure output port 13b is connected to the air inlet of the front cover 11 of the cylinder.

[0056] When the pilot valve assembly 20 is energized, it drives the main valve assembly 10 to switch the output path through the air circuit. The first working air pressure output port 13a and the second working air pressure output port 13b output simultaneously. One end of the cylinder receives pressure to drive the first piston 15 to move, while the other end receives a buffer back pressure. The two opposing forces can slow down the extension speed of the cylinder, effectively preventing the heavy load from falling too fast and causing a dangerous accident.

[0057] Specifically, when the pilot valve is energized, the coil in the pilot valve assembly 20 is energized and generates a magnetic force to attract the internal moving iron core 25. After the moving iron core 25 is attracted, the pilot valve working port 26b is opened, and gas enters the internal cavity of the valve seat 26. At this time, the gas enters the pilot gas inlet passage corresponding to the front cover 11 through the valve seat 26. The front cover 11 guides this gas to the first piston 15, which becomes the pilot gas that drives the piston, thereby pushing the valve stem 14 to move.

[0058] After the power is cut off, the coil loses its magnetic force, and the moving iron core 25 is reset by the spring. At this time, the pilot valve assembly 20 returns to the normally closed state. As the moving iron core 25 is reset, it drives the push rod 23 and the first rubber plug 22 upward, causing the pilot valve exhaust port 26a to open and expel the internal pilot gas. After the pilot gas is expelled, it will not put pressure on the valve stem 14. The reset spring 18 pushes the valve stem 14 back to its original position to block the valve body 13, completing one action.

[0059] When the pilot valve assembly 20 is not energized, the return spring 18 pushes the second piston 16 to reset the valve stem 14. At this time, the two external air supply ports 13c, P1 and P3, are blocked. As long as the pressure value of the proportional pressure valve at the front end of the external air supply port 13c of P2 is adjusted in advance, the output force of the cylinder can balance the weight of the load. The actuator cylinder can drive heavy machinery or tools to remain stably stationary within the stroke range. During operation, the spatial position of the load can be flexibly changed manually.

[0060] Specifically, when the pilot valve is not energized, pilot gas enters from the pilot gas port 11a at the front cover 11 position, and is guided into the valve seat 26 of the pilot valve through the flow channel. Since the pilot valve is normally closed, the gas is blocked by the second rubber plug 24 at this time.

[0061] Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A pilot-operated back pressure switching valve, characterized in that, include: The main valve assembly (10) includes a pilot valve assembly (20) and a connector assembly (30) located at the front end of the main valve assembly (10). The connector assembly (30) supplies power to the pilot valve assembly (20), and the pilot valve assembly (20) controls the operation of the main valve assembly (10) according to the power supply status. The main valve assembly (10) includes a front cover (11), a rear cover (12), a valve body (13), a valve stem (14), a first piston (15), a second piston (16), a spacer (17), and a return spring (18). The front cover (11) is located between the front end of the valve body (13) and the pilot valve assembly (20). The rear cover (12) is located at the rear end of the valve body (13). The valve stem (14) is built into the valve body (13). The piston (15) is abutted between the end of the valve stem (14) and the front cover (11). One end of the second piston (16) abuts against the valve stem (14). The spacer (17) is assembled between the valve body (13) and the rear cover (12) and is sleeved on the outside of the second piston (16). The return spring (18) is located in the spacer (17) and its two ends abut against the other end faces of the rear cover (12) and the second piston (16), respectively.

2. The pilot-operated back pressure switching valve according to claim 1, characterized in that, Sealing gaskets (19) are provided between the front end of the front cover (11) and the front end of the valve body (13), and between the rear end of the rear cover (12) and the rear end of the valve body (13).

3. The pilot-operated back pressure switching valve according to claim 1, characterized in that, The valve body (13) is provided with a first working air pressure output port (13a) and a second working air pressure output port (13b). The first working air pressure output port (13a) and the second working air pressure output port (13b) are both connected to the assembly space where the valve stem (14) is located. The first working air pressure output port (13a) is connected to the air inlet of the rear cover (12) of the cylinder, and the second working air pressure output port (13b) is connected to the air inlet of the front cover (11) of the cylinder.

4. The pilot-operated back pressure switching valve according to claim 3, characterized in that, The valve body (13) has three external air source inlets (13c), and each of the three external air source inlets (13c) is connected to a pressure reducing valve.

5. The pilot-operated back pressure switching valve according to claim 4, characterized in that, The valve body (13) has a main exhaust port (13d) which is connected to the first working air pressure output port (13a).

6. The pilot-operated back pressure switching valve according to claim 5, characterized in that, Sealing gaskets (19) are provided at the first working air pressure output port (13a), the second working air pressure output port (13b), the three external air source vents (13c), the main exhaust port (13d), and the connection between the valve stem (14) and the valve body (13).

7. The pilot-operated back pressure switching valve according to claim 1, characterized in that, The pilot valve assembly (20) includes a coil assembly (21), a first rubber plug (22), a push rod (23), a second rubber plug (24), a moving iron core (25), and a valve seat (26). The moving iron core (25) is slidably disposed in the coil assembly (21), and the second rubber plug (24) is disposed inside the moving iron core (25). One end of the moving iron core (25) abuts against the push rod (23). The push rod (23) and the first rubber plug (22) are disposed in the valve seat (26), and the first rubber plug (22) is located at the other end of the push rod (23).

8. The pilot-operated back pressure switching valve according to claim 7, characterized in that, The valve seat (26) is provided with a pilot valve exhaust port (26a) and a pilot valve working port (26b). The pilot valve exhaust port (26a) is provided in correspondence with the first rubber plug (22), and the pilot valve working port (26b) is provided in correspondence with the second rubber plug (24).

9. The pilot-operated back pressure switching valve according to claim 8, characterized in that, The front cover (11) is provided with a pilot air port (11a), which is located on the outer side of the front cover (11) and communicates with the inside of the valve seat (26).

10. The pilot-operated back pressure switching valve according to claim 9, characterized in that, The front cover (11) is provided with a pilot air intake passage (11b) and a pilot exhaust passage (11c) on the side facing the pilot valve assembly (20). The pilot air intake passage (11b) is connected to the pilot valve working port (26b), and the pilot exhaust passage (11c) is connected to the pilot valve exhaust port (26a).

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