Pilot valve of pneumatic spraying machine

Abstract

The utility model relates to the technical field of pilot valves, and discloses a pilot valve of a pneumatic type coating machine, which comprises a pilot valve body, a cylinder top wall, a cylinder lower cover, a reversing piston, an air inlet hole, an air exchange hole, an air inlet channel, an air exchange channel, a reset spring, an exhaust channel and an exhaust hole. By the adoption of the structure, the cost can be reduced by using the two same pilot valves; according to the reversing valve, the exhaust hole is formed in the pilot valve, so that an end piston cavity of the reversing mechanism is prevented from being communicated with the outside all the time while effective exhaust is carried out, the problem of insufficient pressure during air intake or large resistance during air exhaust is solved, and the reversing reliability is improved; the exhaust hole is formed in the pilot valve, and the pilot valve can be directly disassembled to clean the exhaust hole, so that maintenance is more convenient, and the problem of reversing faults caused by the fact that the exhaust hole is easily blocked is solved.

Description

Technical Field

[0001] This utility model relates to the field of pilot valve technology, specifically a pilot valve for a pneumatic spraying machine. Background Technology

[0002] Currently, many commonly used pneumatic spraying machines use pilot valves with only two channels on the pilot valve body: an air inlet that is normally connected to the air source and a control air inlet that controls the movement of the reversing mechanism. There is no exhaust port; it is a two-position, two-way valve structure. Then, an exhaust port is provided on the upper and lower end covers of the piston chamber of the reversing mechanism. When the valve stem is in the closed position (the piston in the cylinder is not in contact with the valve stem), the control port and the air inlet on the pilot valve body are isolated. When the valve stem is in the open position (the piston in the cylinder pushes the valve stem open), the control port and the air inlet on the pilot valve body are connected, and compressed air enters the piston end of the reversing mechanism, pushing the reversing piston to the other end to achieve reversal. After reversal, the piston in the cylinder moves away from the valve stem, the valve stem resets, and the control port and the air inlet on the pilot valve body are isolated. The compressed air at the piston end of the reversing mechanism is discharged through the exhaust port on the piston chamber end cover of the reversing mechanism. Because this exhaust port is always open to the atmosphere, it also exhausts air when the valve stem is in the open position and compressed air enters the piston end of the reversing mechanism, pushing the reversing piston to the other end. In other words, it exhausts air even when it doesn't need to. Therefore, the diameter of this exhaust port can only be around 1.5mm. If it's too large, the intake pressure will be insufficient; if it's too small, the exhaust resistance will be high. This exhaust port is easily clogged by impurities in the compressed air, causing reversing malfunctions in the spray painting machine.

[0003] Therefore, the present invention aims to explore a pilot valve for a pneumatic spraying machine, which improves the reliability of the switching mechanism, reduces the failure rate, has a simple structure, is easy to maintain, and is interchangeable, so as to replace the pilot valves of existing pneumatic spraying machines on the market. Utility Model Content

[0004] This utility model mainly provides a pilot valve for a pneumatic spraying machine, which solves the problems of existing pilot valves that only have an air inlet and a control air inlet, but no exhaust port. As a result, the exhaust port is located on the reversing mechanism, which is always connected to the atmosphere and is always venting, leading to low reliability. In addition, the exhaust port is easily blocked by impurities, causing reversing failures of the spraying machine and making it difficult to maintain.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A pilot valve for a pneumatic spraying machine includes a pilot valve body, a cylinder top wall, a cylinder bottom cover, and a reversing piston. Two pilot valve bodies are detachably connected to the cylinder top wall and the cylinder bottom cover, respectively. Both the cylinder top wall and the cylinder bottom cover have air inlets that are normally connected to an air source, and both have ventilation holes that communicate with the end piston chamber of the reversing piston. The ventilation holes on the cylinder top wall are connected to the upper end of the end piston chamber, and the ventilation holes on the cylinder bottom cover are connected to the upper end of the end piston chamber. The vent is connected to the lower end of the piston chamber at the end; the pilot valve body has an intake channel that is normally connected to the intake port and an exchange channel that is normally connected to the exchange port; the valve chamber of the pilot valve body is provided with a valve stem and a return spring for driving the valve stem to reset; the valve stem is provided with an exhaust channel, the lower end of which is normally connected to the exchange channel; the upper end of the pilot valve body is provided with a valve cover, the valve cover is provided with an exhaust hole, and the exhaust hole is connected to the upper end of the exhaust channel after reset.

[0007] Furthermore, a step is provided on the valve stem, and the return spring is disposed between the step and the valve cover.

[0008] Furthermore, the exhaust channel includes a lower horizontal hole, a vertical hole, and an upper horizontal hole; the lower horizontal hole is normally connected to the ventilation channel, and the upper horizontal hole, after being reset, is connected to the exhaust hole.

[0009] Furthermore, the valve body mounting holes on the cylinder top wall and cylinder bottom cover are designed as stepped holes, wider at the top and narrower at the bottom. With this structure, the valve body mounting holes are designed as stepped holes, preventing the sealing ring on the pilot valve body from being scratched by the vent hole during pilot valve body installation.

[0010] Furthermore, the pilot valve body includes a fixed seat that can be detachably connected to the cylinder top wall and the cylinder bottom cover, and a disassembly seat that can be detachably connected to the fixed seat, wherein the valve cover is detachably connected to the disassembly seat.

[0011] Beneficial effects: The structure of this application, using two identical pilot valve bodies, can reduce costs; on the pilot valve, while effectively venting, the piston chamber at the end of the reversing mechanism is prevented from always being connected to the outside, avoiding problems such as insufficient pressure during intake or high resistance during exhaust, thus increasing the reliability of reversing; by setting the exhaust port on the pilot valve, the pilot valve can be directly disassembled for cleaning of the exhaust port, making maintenance more convenient and reducing the problem of reversing failure caused by easy blockage of the exhaust port. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the pilot valve structure in Example 1;

[0013] Figure 2 This is a schematic diagram of the pilot valve stem after movement in Example 1;

[0014] Figure 3 This is a schematic diagram of the pilot valve structure in Example 2;

[0015] Figure 4 This is a schematic diagram of the pilot valve stem after movement in Example 2.

[0016] Reference numerals: 1. Cylinder top wall; 2. Pilot valve body; 3. Valve stem; 4. Return spring; 5. Valve cover; 6. First sealing ring; 7. Second sealing ring; 8. Third sealing ring; 9. Fourth sealing ring; 10. Fifth sealing ring; 11. Sixth sealing ring; 12. Inner piston; 13. Cylinder lower cover; 14. Reversing piston; 1a. Intake port; 1b. Venting port; 1c. End piston chamber; 2a. Intake passage; 2b. Venting passage; 3a. Lower horizontal hole; 3b. Vertical hole; 3c. Upper horizontal hole; 5a. Inner annular groove; 5b. Exhaust port; 15. Fixing seat; 16. Disassembly seat. Detailed Implementation

[0017] The pilot valve technology of a pneumatic spraying machine according to this utility model will be further described in detail below with reference to the embodiments.

[0018] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0019] Example 1:

[0020] like Figure 1 , Figure 2As shown, a pilot valve for a pneumatic spraying machine includes a pilot valve body 2, a cylinder top wall 1, a cylinder lower cover 13, and a reversing piston 14. The two pilot valve bodies 2 are detachably connected to the cylinder top wall 1 and the cylinder lower cover 13, respectively. Both the cylinder top wall 1 and the cylinder lower cover 13 have air inlets 1a that are normally connected to an air source, and both the cylinder top wall 1 and the cylinder lower cover 13 have vent holes 1b that communicate with the end piston chamber 1c of the reversing piston 14. The vent holes 1b on the cylinder top wall 1 are connected to the upper end of the end piston chamber 1c. The cylinder lower cover 1... The vent 1b on the pilot valve body 2 is connected to the lower end of the piston chamber 1c. The pilot valve body 2 has an intake channel 2a that is normally connected to the intake port 1a and a venting channel 2b that is normally connected to the vent 1b. The valve chamber of the pilot valve body 2 contains a valve stem 3 and a return spring 4 for resetting the valve stem 3. The valve stem 3 has an exhaust channel, the lower end of which is normally connected to the venting channel 2b. The upper end of the pilot valve body 2 has a valve cover 5 with an exhaust port 5b connected to the upper end of the reset exhaust channel. The valve stem 3 has a step, and the return spring 4 is positioned between the step and the valve cover 5. The exhaust channel includes a lower horizontal hole 3a, a vertical hole 3b, and an upper horizontal hole 3c. The lower horizontal hole 3a is normally connected to the venting channel 2b, and the reset upper horizontal hole 3c is connected to the exhaust port 5b. The valve body mounting holes on the cylinder top wall 1 and cylinder lower cover 13 are designed as stepped holes, wider at the top and narrower at the bottom. Simultaneously, the valve cover 5, valve stem 3, pilot valve body 2, cylinder top wall 1, and cylinder lower cover 13 are equipped with a first sealing ring 6, a second sealing ring 7, a third sealing ring 8, a fourth sealing ring 9, a fifth sealing ring 10, and a sixth sealing ring 11. The multiple sealing rings effectively prevent airflow cross-contamination and isolate the various components. The connection between the exhaust port 5b and the upper end of the reset exhaust channel refers to the alignment and communication between the upper horizontal hole 3c on the valve stem 3 and the inner annular groove 5a on the valve cover 5. The venting port 1b on the cylinder lower cover 13 is connected to the lower end of the end piston chamber 1c via a guide hole on the cylinder body.

[0021] Working principle: When the inner piston 12 is running in the middle position, both the upper and lower valve stems 3 are in the closed position, and the air exchange passage 2b and the air intake passage 2a on the pilot valve body 2 are blocked. At the same time, the piston chambers 1c at the upper and lower ends of the reversing piston 14 are connected to the atmosphere.

[0022] When the inner piston 12 moves to its upper end and pushes open the valve stem 3, the upper transverse hole 3c on the valve stem 3 is misaligned with the inner annular groove 5a on the valve cover 5, blocking the air exchange passage 2b on the pilot valve body 2 from the atmosphere. The valve stem 3 continues to move, connecting the air exchange passage 2b on the pilot valve body 2 with the intake passage 2a. At this time, compressed air reaches the piston chamber 1c at the upper end of the reversing piston 14 through the intake hole 1a on the cylinder top wall 1, the intake passage 2a on the pilot valve body 2, the air exchange passage 2b, and the air exchange hole 1b on the cylinder top wall 1, pushing the reversing piston 14 downwards to achieve reversal. After reversal, the cylinder's intake and exhaust directions change, causing the inner piston 12 to move downwards. When the inner piston 12 leaves the valve stem 3, the return spring 4 returns the valve stem 3 to the closed position. At this time, the step on the valve stem 3 and the third sealing ring 8 block the air exchange passage 2b and the air intake passage 2a on the pilot valve body 2. At the same time, the upper horizontal hole 3c on the valve stem 3 is aligned and connected with the inner ring groove 5a on the valve cover 5. The compressed air in the piston chamber 1c at the upper end of the switching piston 14 is discharged into the atmosphere through the air exchange hole 1b on the cylinder top wall 1, the air exchange passage 2b on the pilot valve body 2, the lower horizontal hole 3a, the vertical hole 3b, the upper horizontal hole 3c on the valve stem 3, the inner ring groove 5a on the valve cover 5, and the exhaust hole 5b.

[0023] Similarly, when the inner piston 12 moves to its lower end and pushes open the valve stem 3, the upper transverse hole 3c on the valve stem 3 is misaligned with the inner annular groove 5a on the valve cover 5, blocking the air exchange passage 2b on the pilot valve body 2 from the atmosphere. The valve stem 3 continues to move, connecting the air exchange passage 2b on the pilot valve body 2 with the intake passage 2a. At this time, compressed air reaches the piston chamber 1c at the lower end of the reversing piston 14 through the intake hole 1a on the cylinder lower cover 13, the intake passage 2a on the pilot valve body 2, the air exchange passage 2b, and the air exchange hole 1b on the cylinder lower cover 13, pushing the reversing piston 14 upward to achieve reversing. After reversing, the cylinder's intake and exhaust directions change again, thus realizing the reciprocating motion of the pneumatic motor.

[0024] Example 2:

[0025] like Figure 3 , Figure 4As shown, a pilot valve for a pneumatic sprayer differs from Embodiment 1 in that: the pilot valve body includes a fixed seat 15 detachably connected to the cylinder top wall 1 and the cylinder lower cover 13, and a disassembly seat 16 detachably connected to the fixed seat 15. The valve cover 5 is detachably connected to the disassembly seat 16. In this embodiment, a second sealing ring 7 is disposed between the fixed seat 15 and the disassembly seat 16. An air exchange channel 2b is disposed on the disassembly seat 16. Embodiments 1 and 2 operate on the same principle. Because the fixing screws on the pilot valve body 2 are covered by paint mist after the sprayer has been used for a period of time, making disassembly difficult; therefore, with this structure, during inspection and maintenance, it is not necessary to disassemble the fixed seat; instead, the disassembly seat and other components can be directly removed, making installation and disassembly more convenient.

[0026] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A pilot valve for a pneumatic spraying machine, characterized in that: The system includes a pilot valve body, a cylinder top wall, a cylinder bottom cover, and a reversing piston. Two pilot valve bodies are detachably connected to the cylinder top wall and the cylinder bottom cover, respectively. Both the cylinder top wall and the cylinder bottom cover have air inlets that are normally connected to an air source, and both have ventilation holes that communicate with the end piston chamber of the reversing piston. The ventilation hole on the cylinder top wall communicates with the upper end of the end piston chamber, and the ventilation hole on the cylinder bottom cover communicates with the end piston chamber. The lower end of the plug cavity is connected; the pilot valve body is provided with an air intake channel that is normally connected to the air intake port and an air exchange channel that is normally connected to the air exchange port; a valve stem and a return spring for driving the valve stem to reset are provided in the valve cavity of the pilot valve body; an exhaust channel is provided on the valve stem, and the lower end of the exhaust channel is normally connected to the air exchange channel; a valve cover is provided at the upper end of the pilot valve body, and an exhaust hole is provided on the valve cover, and the exhaust hole is connected to the upper end of the exhaust channel after reset.

2. The pilot valve of a pneumatic spraying machine according to claim 1, characterized in that: The valve stem is provided with a step, and the return spring is disposed between the step and the valve cover.

3. The pilot valve of a pneumatic spraying machine according to claim 1, characterized in that: The exhaust passage includes a lower horizontal hole, a vertical hole, and an upper horizontal hole; the lower horizontal hole is normally connected to the ventilation passage, and the upper horizontal hole, after being reset, is connected to the exhaust hole.

4. The pilot valve of a pneumatic spraying machine according to claim 1, characterized in that: The valve body mounting holes on the cylinder top wall and cylinder bottom cover are designed as stepped holes, with the top being larger than the bottom.

5. The pilot valve of a pneumatic spraying machine according to claim 1, characterized in that: The pilot valve body includes a fixed seat that can be detachably connected to the cylinder top wall and the cylinder bottom cover, and a disassembly seat that can be detachably connected to the fixed seat, wherein the valve cover is detachably connected to the disassembly seat.

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