Pressure relief valve for cooling liquid storage tank of water-cooled piston aircraft engine

Abstract

The invention relates to a water-cooled piston aircraft engine cooling liquid storage tank pressure relief valve which comprises a cylindrical annular valve seat and an umbrella cap-shaped valve shell, an external thread connector extending downwards is formed at the lower end of the valve seat, a connecting sleeve with an L-shaped section is formed on the upper end face of the valve seat, the upper end of the connecting sleeve abuts against the inner wall of the valve shell, and the lower end of the connecting sleeve abuts against the inner wall of the valve shell. An outer sealing ring is fixedly connected to the connecting sleeve in an inserted and sleeved mode and abuts against the inner wall of the valve shell in a pressing mode. A cylindrical-ring-shaped connector and a connecting pipe are formed at the upper end and the lower end of the middle of the valve shell respectively, the connecting pipe is inserted into the valve seat and abuts against the inner wall of the valve seat, the lower end of the connecting pipe extends out of the valve seat to be sleeved with a pressure relief spring, the upper end of the pressure relief spring abuts against the lower end face of the external thread connector, and the lower end of the pressure relief spring abuts against the limiting check ring. The limiting check ring is fixedly sleeved at the lower end of the connecting pipe. The pressure relief valve adopts double-spring graded pressure control, the pressure control stability and precision are high, and the pressure relief valve adapts to pressure fluctuation of all working conditions of starting, cruising and landing of an airplane.

Description

Technical Field

[0001] This invention relates to the technical field of release valves, and more specifically to a pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine. Background Technology

[0002] Currently, water-cooled piston aircraft engines are the core power unit of light general aviation aircraft. The coolant used to cool the pistons is stored in a coolant reservoir. The coolant reservoir is a key component for balancing coolant volume changes and stabilizing system pressure. Therefore, a release valve needs to be installed inside the coolant reservoir. This valve is used to monitor and regulate the coolant pressure in the reservoir in real time to prevent overpressure rupture or low-pressure cavitation caused by high-altitude low-pressure environments or high engine load operation. At the same time, it is adapted to special operating conditions such as aircraft vibration and sudden temperature changes to ensure the stability of the coolant circulation system, thereby ensuring the continuous and efficient operation of the water-cooled piston engine.

[0003] However, compared to ground vehicle engines, aircraft engines face a much harsher operating environment: First, during high-altitude flight, the low external air pressure causes fluctuations in the pressure difference between the inside and outside of the coolant reservoir. Improper pressure control can lower the boiling point of the coolant, generating bubbles and causing cavitation, thus affecting heat dissipation efficiency. Second, during takeoff and landing, the engine's operating conditions change frequently, resulting in drastic pressure changes within the reservoir in a short period, placing extremely high demands on the response speed of the pressure relief valve. Third, aircraft continuously experience vibrations of 10-2000Hz during flight, which can easily lead to loosening of pressure relief valve components and seal failure. Fourth, the large temperature range at high altitudes means the coolant is constantly in extreme temperature cycling, imposing strict requirements on the temperature resistance and corrosion resistance of the valve material. Currently, the pressure relief valves used in the coolant reservoirs of water-cooled piston aircraft engines have the following technical shortcomings: 1. Poor adaptability to operating conditions: Most valves use a single spring for pressure control, which cannot accurately match the aircraft engine's "start-cruise-landing" cycle. 1. Pressure fluctuations throughout the entire process can easily lead to problems such as overpressure without pressure relief during cruise and underpressure accidental pressure relief during descent; 2. Insufficient sealing reliability: Seals are mostly made of ordinary rubber, which is prone to aging and hardening under sudden temperature changes at high altitudes and long-term immersion in water / glycol coolant, resulting in leakage. In addition, some assembly processes do not avoid the contamination of the sealing surface by thread-locking adhesives (such as Loctite), further reducing sealing performance; 3. Weak vibration resistance and corrosion resistance: The core components (such as valve cores and retaining rings) have insufficient material strength and are prone to structural deformation under long-term aircraft vibration. In addition, some materials are not resistant to coolant corrosion and have a short service life (usually less than 3,000 flight hours). To address the above problems, there is an urgent need to develop a pressure relief valve that is suitable for the working conditions of coolant reservoirs in water-cooled piston aircraft engines, has reliable sealing, precise pressure control, vibration and corrosion resistance, and is easy to maintain, filling the application gap of existing technology in the aviation field. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a pressure relief valve for the coolant reservoir of a water-cooled piston aircraft engine. This pressure relief valve adopts a dual-spring graded pressure control, which provides high stability and accuracy in pressure control and is suitable for pressure fluctuations throughout the entire operating conditions of an aircraft, from start-up to cruise and landing.

[0005] A pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine includes a cylindrical annular valve seat and a cap-shaped valve body. The lower end of the valve seat has a downwardly extending external threaded connector, and the upper end of the valve seat has an L-shaped connecting sleeve. The upper end of the connecting sleeve abuts against the inner wall of the valve body. An external sealing ring is inserted and fixedly connected to the connecting sleeve, and the external sealing ring presses against the inner wall of the valve body. The upper and lower ends of the middle part of the valve body have cylindrical annular interfaces and connecting pipes respectively. The connecting pipe is inserted into the valve seat and abuts against the inner wall of the valve seat. The lower end of the connecting pipe extends out of the valve seat and is sleeved on a pressure relief spring. The upper end of the pressure relief spring presses against the lower end face of the external threaded connector, and the lower end presses against a limiting retaining ring. The limiting retaining ring is sleeved and fixed to the lower end of the connecting pipe. An annular pressure relief chamber is formed between the outer wall of the upper end of the connecting pipe and the inner wall of the connecting sleeve. Several pressure relief holes are formed on the pipe wall below the pressure relief chamber. A limiting protrusion ring is formed on the inner wall of the connecting pipe above the pressure relief holes. A piston hole connecting the connecting pipe and the interface is formed in the valve shell above the limiting protrusion ring. A piston is inserted into the piston hole. A central countersunk hole is formed on the lower end face of the piston. Several vent holes penetrating the outer wall of the piston are formed on the inner wall of the upper end of the central countersunk hole. A conical expansion hole is formed at the outer end of the vent hole. A vent ring groove is formed on the inner wall of the piston hole outside the expansion hole. An upper stepped groove penetrating the lower end face of the piston and forming an annular shape is formed on the inner wall of the upper part of the limiting protrusion ring. Vertical pressure stabilizing springs are inserted in the lower stepped groove and the upper stepped groove. The upper and lower ends of the pressure stabilizing springs press against the piston and the limiting protrusion ring, respectively. A cylindrical annular pressure control sleeve is inserted and fixed inside the valve housing interface. The lower end of the pressure control sleeve has an L-shaped annular connection port. An inner sealing ring is clamped and fixed between the outer wall of the lower end of the annular connection port and the inner wall of the interface. The upper end of the piston has a conical sealing contact surface. The inner sealing ring presses against the sealing contact surface of the piston. A cylindrical filter element is inserted inside the pressure control sleeve. The lower end of the filter element abuts against the annular connection port, and the upper end abuts against the retaining spring. The retaining spring is locked onto the inner wall of the pressure control sleeve.

[0006] Preferably, the outer ring at the upper end of the connecting sleeve is formed with a conical connecting surface, the inner wall of the outer side of the valve housing is a conical surface, and the inner wall of the outer side of the valve housing and the connecting surface on the connecting sleeve are in the same conical surface. The outer sealing ring is pressed against the inner wall of the outer side of the valve body, and a support ring is sleeved on the lower part of the outer sealing ring. The support ring is inserted and fixed on the valve seat.

[0007] Preferably, an O-ring is fitted on the external threaded connector, and an annular groove is formed on the inner wall of the upper end of the external threaded connector. The O-ring is inserted into the annular groove and pressed against the lower end face of the valve seat. An annular positioning groove is formed on the inner wall of the lower end of the external threaded connector. The upper end of the pressure relief spring is inserted into the positioning groove of the external threaded connector and pressed against the upper bottom surface of the positioning groove.

[0008] Preferably, an annular groove is formed on the outer wall of the lower end of the connecting pipe, and an annular elastic retaining ring is inserted into the groove. An annular connecting groove is formed on the inner wall of the lower end of the limiting retaining ring, and the elastic retaining ring is inserted into the connecting groove of the limiting retaining ring and pressed against the limiting retaining ring.

[0009] Preferably, the upper end of the interface is fixed with a positioning support sleeve, the pressure control sleeve is inserted and fixed inside the positioning support sleeve, and a retaining spring groove is formed on the inner wall of the upper part of the pressure control sleeve, and the retaining spring is engaged in the retaining spring groove of the pressure control sleeve.

[0010] Preferably, the spring force of the stabilizing spring is less than the spring force of the relief spring.

[0011] Preferably, the lower stepped groove of the valve housing has several pressure relief holes formed on its inner wall, which are connected to the pressure relief chamber. A valve core with an inverted T-shaped cross-section is inserted into the lower stepped groove. The lower end face of the valve core presses against the bottom surface of the lower stepped groove, and the outer wall of the lower end of the valve core presses against the inner wall of the lower stepped groove and covers the pressure relief holes. An air inlet hole is formed in the middle of the valve core. The air inlet hole consists of an upper conical guide hole and a lower circular small hole. The diameter of the upper end of the guide hole is smaller than the diameter of the small hole. The lower part of the pressure stabilizing spring is sleeved on the valve core and presses against the valve core. A drain hole connected to the pressure relief chamber is formed on the outer wall of one side of the valve housing. A cylindrical annular internal threaded release port is formed on the outer wall of the valve housing at the outlet of the drain hole. A pressure-holding sleeve is screwed into the internal threaded release port. A one-way valve plate is clamped and fixed between the pressure-holding sleeve and the valve housing. The one-way valve plate covers the outlet of the drain hole.

[0012] Preferably, the one-way valve plate includes a circular central valve plate and an annular outer ring plate. The central valve plate covers the drain hole of the valve housing, and the outer ring plate is clamped and fixed between the pressure sleeve and the valve housing. A connecting piece is formed between one side of the outer ring of the central valve plate and the inner ring of the outer ring plate.

[0013] Fiberglass sealing rings are respectively embedded and fixed on the outer wall of the connecting pipe above the pressure relief hole and on the outer wall of the lower part of the valve core. The fiberglass sealing rings are respectively pressed against the inner wall of the valve seat and the inner wall of the lower step groove of the valve body.

[0014] The beneficial effects of this invention are as follows: 1. This pressure relief valve adopts dual-spring graded pressure control, which has high stability and accuracy, and is suitable for pressure fluctuations in the entire operating condition of aircraft from start-up to cruise to landing.

[0015] 2. The sealing elements inside this pressure relief valve are not immersed in the coolant, which reduces the impact of the coolant on the sealing elements, reduces the aging and corrosion of the sealing elements, and thus indirectly improves the sealing performance of the pressure relief valve.

[0016] 3. This pressure relief valve has a simple and compact structure, similar to a modular design, which makes it easy to assemble and disassemble, and facilitates the maintenance and replacement of internal components. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention in half section; Figure 2 This is a schematic diagram of the intake pressure stabilization structure of the present invention; Figure 3 This is a schematic diagram of the pressure relief under low-pressure conditions according to the present invention; Figure 4 This is a schematic diagram of the pressure relief under high pressure conditions according to the present invention; Figure 5 A schematic diagram of the structure of the present invention with the valve core added; Figure 6 for Figure 5 A magnified view of a portion of point A in the middle; Figure 7 This is a schematic diagram of the pressure relief of the valve core under low pressure conditions according to the present invention.

[0018] In the diagram: 1. Valve seat; 11. External threaded connector; 12. Positioning groove; 13. Connecting sleeve; 2. Valve body; 21. Connecting pipe; 22. Interface; 23. Pressure relief hole; 24. Limiting protrusion ring; 25. Lower step groove; 26. Piston hole; 27. Vent ring groove; 28. Slot; 29. ​​Pressure relief hole; 210. Drain hole; 211. Internal threaded release port; 3. Piston; 31. Center countersunk hole; 32. Upper step groove; 33. Vent hole; 34. Enlarged hole; 35. Sealing contact surface; 4. Pressure stabilizing spring. 5. Spring; 6. Fiberglass sealing ring; 7. Pressure control sleeve; 8. Annular connector; 9. Snap ring groove; 10. Inner sealing ring; 11. Pressure relief spring; 22. Limiting ring; 33. Outer sealing ring; 44. Filter element; 55. Snap ring; 66. Positioning support sleeve; 77. Support ring; 88. O-ring; 99. Elastic snap ring; 10. Valve core; 11. Guide hole; 12. Small hole; 13. One-way valve plate; 14. Center valve plate; 15. Outer ring plate; 16. Connecting plate; 17. Pressure holding sleeve. Detailed Implementation

[0019] Example: See Figure 1As shown, a pressure relief valve for a coolant reservoir of a water-cooled piston aircraft engine includes a cylindrical annular valve seat 1 and a cap-shaped valve body 2. The lower end of the valve seat 1 is formed with a downwardly extending external threaded connector 11, and the upper end of the valve seat 1 is formed with an L-shaped connecting sleeve 13. The upper end of the connecting sleeve 13 abuts against the inner wall of the valve body 2, and an outer sealing ring 10 is inserted and fixed on the connecting sleeve 13. The outer sealing ring 10 presses against the inner wall of the valve body 2. The upper and lower ends of the middle part of the valve body 2 are respectively formed with a cylindrical annular interface 22 and a connecting pipe 21. The connecting pipe 21 is inserted into the valve seat 1 and abuts against the inner wall of the valve seat 1. The lower end of the connecting pipe 21 extends out of the valve seat 1 and is sleeved on a pressure relief spring 8. The upper end of the pressure relief spring 8 presses against the lower end face of the external threaded connector 11, and the lower end presses against a limiting retaining ring 9. The limiting retaining ring 9 is sleeved and fixed on the lower end of the connecting pipe 21. An annular pressure relief chamber a is formed between the outer wall of the upper end of the connecting pipe 21 and the inner wall of the connecting sleeve 13. Several pressure relief holes 23 are formed on the wall of the connecting pipe 21 below the pressure relief chamber a. A limiting protrusion ring 24 is formed on the inner wall of the connecting pipe 21 above the pressure relief holes 23. A piston hole 26 connecting the connecting pipe 21 and the interface 22 is formed in the valve shell 2 above the limiting protrusion ring 24. A piston 3 is inserted into the piston hole 26, and the diameter of the piston hole 26 is equal to the diameter of the piston 3. A central countersunk hole 31 is formed on the lower end face of the piston 3. The inner wall of the upper end of the central countersunk hole 31... The piston 3 has several vent holes 33 that penetrate the outer wall of the piston 3. The outer end of the vent holes 33 is formed with a conical enlarged hole 34. The inner wall of the piston hole 26 outside the enlarged hole 34 is formed with a vent ring groove 27. The inner wall of the central countersunk hole 31 of the piston 3 is formed with an upper stepped groove 32 that penetrates the lower end face of the piston 3 and is annular. The inner wall of the upper part of the limiting protrusion ring 24 is formed with an annular lower stepped groove 25. Vertical pressure stabilizing springs 4 are inserted in the lower stepped groove 25 and the upper stepped groove 32. The upper and lower ends of the pressure stabilizing springs 4 press against the piston 3 and the limiting protrusion ring 24, respectively. A cylindrical annular pressure control sleeve 6 is inserted and fixed inside the interface 22 of the valve housing 2. The lower end of the pressure control sleeve 6 is formed with an L-shaped annular connection port 61. An inner sealing ring 7 is clamped and fixed between the outer wall of the lower end of the annular connection port 61 and the inner wall of the interface 22. The upper end of the piston 3 has a conical sealing contact surface 35 formed on the outer ring. The inner sealing ring 7 presses against the sealing contact surface 35 of the piston 3. A cylindrical filter element 20 is inserted inside the pressure control sleeve 6. The filter element 20 is preferably an air filter element. The lower end of the filter element 20 abuts against the annular connection port 61 and the upper end abuts against the retaining spring 30. The retaining spring 30 is locked on the inner wall of the pressure control sleeve 6. The pressure relief spring 8 and the pressure stabilizing spring 4 are both made of aviation corrosion-resistant alloy springs with different preload strokes (18mm / 132mm) and stiffness. They have good vibration resistance and corrosion resistance, and are suitable for pressure fluctuations in the entire operating condition of aircraft "start-cruise-landing", achieving precise pressure control in the range of 0.1-0.5MPa (deviation ≤ ±0.05MPa).

[0020] The outer ring of the upper end of the connecting sleeve 13 is formed with a conical connecting surface, and the inner wall of the outer side of the valve housing 2 is a conical surface. The inner wall of the outer side of the valve housing 2 and the connecting surface on the connecting sleeve 13 are in the same conical surface, that is, the two are in surface contact, which makes the stability better. The outer sealing ring 10 is pressed against the inner wall of the outer side of the valve body 2. A support ring 50 is sleeved on the lower part of the outer sealing ring 10. The support ring 50 is inserted and fixed on the valve seat 1. The support ring 50 can effectively prevent the outer sealing ring 10 on the valve seat 1 from falling off.

[0021] An O-ring 60 is fitted on the external threaded connector 11. An annular groove is formed on the inner wall of the upper end of the external threaded connector 11. The O-ring 60 is inserted into the annular groove and pressed against the lower end face of the valve seat 1. This pressure relief valve is screwed onto the coolant reservoir. The component screwed onto the coolant reservoir is the valve seat 1, and its O-ring 60 is used for effective sealing between the valve seat 1 and the coolant reservoir.

[0022] An annular positioning groove 12 is formed on the inner wall of the lower end of the external threaded connector 11. The upper end of the pressure relief spring 8 is inserted into the positioning groove 12 of the external threaded connector 11 and pressed against the upper bottom surface of the positioning groove 12. The positioning groove 12 is used to constrain the pressure relief spring 8, thereby improving stability.

[0023] An annular groove 28 is formed on the outer wall of the lower end of the connecting pipe 21, and an annular elastic retaining ring 70 is inserted into the groove 28. An annular connecting groove 91 is formed on the inner wall of the lower end of the limiting retaining ring 9. The elastic retaining ring 70 is inserted into the connecting groove 91 of the limiting retaining ring 9 and presses against the limiting retaining ring 9. The elastic retaining ring 70 can restrict the downward movement of the limiting retaining ring 9. The advantage is that the limiting retaining ring 9 is completely fixed in the connecting pipe 21. The limiting retaining ring 9 can be disassembled by removing the elastic retaining ring 70, which facilitates the assembly and disassembly of the entire release valve.

[0024] The upper end of the interface 22 is fixed with a positioning support sleeve 40, and the pressure control sleeve 6 is inserted and fixed inside the positioning support sleeve 40. A retaining spring groove 62 is formed on the inner wall of the upper part of the pressure control sleeve 6, and the retaining spring 30 is locked in the retaining spring groove 62 of the pressure control sleeve 6. The positioning support sleeve 40 can restrict the radial movement of the pressure control sleeve 6, which is equivalent to a bushing and improves the installation accuracy of the positioning support sleeve 40.

[0025] The spring force of the stabilizing spring 4 is less than the spring force of the relief spring 8.

[0026] See Figure 5 , 6 As shown, the lower stepped groove 25 of the valve housing 2 has several pressure relief holes 29 formed on its inner wall, which are connected to the pressure relief chamber a. A valve core 80 with an inverted T-shaped cross-section is inserted into the lower stepped groove 25. The lower end face of the valve core 80 presses against the bottom surface of the lower stepped groove 25, and the outer wall of the lower end of the valve core 80 presses against the inner wall of the lower stepped groove 25 and covers the pressure relief holes 29. An air inlet hole is formed in the middle of the valve core 80. The air inlet hole consists of an upper conical guide hole 801 and a lower circular small hole 802. The diameter of the upper end of the guide hole 801 is smaller than the diameter of the small hole 802. The lower part of the pressure stabilizing spring 4 is sleeved on the valve core 80 and presses against the valve core 80. A drain hole 210 communicating with the pressure relief chamber a is formed on the outer wall of one side of the valve housing 2. A cylindrical annular internal threaded release port 211 is formed on the outer wall of the valve housing 2 at the outlet of the drain hole 210. A pressure holding sleeve 100 is screwed into the internal threaded release port 211. A one-way valve plate 90 is clamped and fixed between the pressure holding sleeve 100 and the valve housing 2. The one-way valve plate 90 covers the outlet of the drain hole 210. Under normal circumstances, when the pressure inside the coolant reservoir increases and falls within the low-pressure range, the pressure acts on the vent hole 33 of piston 3 and the vent ring groove 27 of piston hole 26, causing piston 3 to compress the pressure-stabilizing spring 4 and move downwards. This allows the upper part of piston 3 to move downwards into the vent ring groove 27, and the coolant is discharged from the port 22 of valve body 2. The coolant then needs to pass through the filter element 20, which is mainly used for air purification and filtration. After passing through the liquid, its air filtration effect weakens, so it needs to be filtered. Frequent replacement is required; however, the proposed solution involves opening multiple channels in the valve housing 2, and adding a valve core 80 inside the piston hole 26. The valve core 80 does not affect the air intake and pressure stabilization of the reservoir. When the reservoir pressure increases and pressure relief is needed, due to the air intake hole structure within the valve core 80, the reservoir pressure primarily acts on the valve core 80, causing it to compress the pressure-stabilizing spring 4 and move upwards. This opens the pressure relief hole 29 on the valve housing 2, allowing the coolant to flow through the pressure relief hole 29, pressure relief chamber a, and drain hole 210, ultimately opening the one-way valve plate 90 for discharge. Figure 7 As shown, this will prevent further contamination of filter element 20 and extend its service life.

[0027] The one-way valve plate 90 includes a circular central valve plate 901 and an annular outer ring plate 902. The central valve plate 901 covers the drain hole 210 of the valve housing 2, and the outer ring plate 902 is clamped and fixed between the pressure sleeve 100 and the valve housing 2. A connecting piece 903 is formed between one side of the outer ring of the central valve plate 901 and the inner ring of the outer ring plate 902. The one-way valve plate 90 can prevent the outflowing air or liquid from flowing into the drain hole 210 and only allow pressure relief to be discharged from the drain hole 210.

[0028] Fiberglass sealing rings 5 ​​are respectively embedded and fixed on the outer wall of the connecting pipe 21 on the upper side of the pressure relief hole 23 and on the outer wall of the lower part of the valve core 80. The fiberglass sealing rings 5 ​​are respectively pressed against the inner wall of the valve seat 1 and the inner wall of the lower step groove 25 of the valve body 2. The fiberglass sealing rings 5 ​​have good temperature resistance, corrosion resistance and high strength, which can improve the sealing performance.

[0029] Working principle: This structure is a pressure relief valve for the coolant reservoir of a water-cooled piston aircraft engine. The structure of the pressure relief valve is as follows: Figure 1 As shown, its main body consists of a valve seat 1 and a valve body 2. A pressure relief spring 8 is provided between the valve seat 1 and the valve body 2 to relieve pressure under high pressure conditions in the coolant reservoir. At the same time, a piston 3 and a pressure stabilizing spring 4 are provided inside the valve body 2. The piston 3 participates in the pressure relief under low pressure conditions in the coolant reservoir. The specific pressure stabilization is as follows: When the coolant reservoir loses pressure, the external atmospheric pressure is greater than the pressure inside the coolant reservoir. Air, filtered by filter element 20, acts on piston 3, causing piston 3 to compress the pressure-stabilizing spring 4 and move downwards. Air then enters the connecting pipe 21 through the vent ring groove 27, vent hole 33, and the inner hole of the limiting protrusion ring 24, and finally enters the coolant reservoir. A schematic diagram of the air intake is shown below. Figure 2 As shown; When the pressure in the coolant reservoir increases, but remains within a low-pressure range, the pressure relief spring 8 does not participate. Under its pressure, a pressure difference is created between the venting ring groove 27 and the venting ring groove 34 of the piston 3 and the venting ring groove 27 of the piston orifice 26. This pressure difference drives the piston 3 to compress the pressure stabilizing spring 4, causing it to move downwards and connect to the outside environment through the venting ring groove 27. The coolant then flows out from the venting ring groove 27 and the interface 22, thus relieving pressure. A schematic diagram of the pressure relief is shown below. Figure 3 As shown; When the pressure in the coolant reservoir continues to increase, reaching a high-pressure state, the pressure relief spring 8 compresses to participate in pressure relief. This causes the entire valve body 2 to move upwards, allowing most of the coolant to flow into the pressure relief chamber a through the pressure relief hole 23, and then out through the outer ring of the valve body 2, thus achieving pressure relief. A schematic diagram of the pressure relief process is shown below. Figure 4 As shown.

[0030] The embodiments described are illustrative of the invention and are not intended to limit the invention. Any person skilled in the art can modify the embodiments without departing from the spirit and scope of the invention; therefore, the scope of protection of the invention should be as set forth in the claims.

Claims

1. A pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine, comprising a cylindrical annular valve seat (1) and a cap-shaped valve body (2), wherein the lower end of the valve seat (1) is formed with a downwardly extending external threaded connector (11), characterized in that: A connecting sleeve (13) with an L-shaped cross section is formed on the upper surface of the valve seat (1). The upper end of the connecting sleeve (13) abuts against the inner wall of the valve body (2). An outer sealing ring (10) is inserted and fixed on the connecting sleeve (13). The outer sealing ring (10) presses against the inner wall of the valve body (2). A cylindrical ring-shaped interface (22) and a connecting pipe (21) are formed at the upper and lower ends of the middle part of the valve body (2). The connecting pipe (21) is inserted into the valve seat (1) and abuts against the inner wall of the valve seat (1). The lower end of the connecting pipe (21) extends out of the valve seat (1) and is sleeved on the pressure relief spring (8). The upper end of the pressure relief spring (8) presses against the lower end face of the external threaded joint (11) and the lower end presses against the limiting ring (9). The limiting ring (9) is sleeved and fixed on the lower end of the connecting pipe (21). An annular pressure relief chamber (a) is formed between the outer wall of the upper end of the connecting pipe (21) and the inner wall of the connecting sleeve (13). Several pressure relief holes (23) are formed on the pipe wall of the connecting pipe (21) below the pressure relief chamber (a). A limiting protrusion ring (24) is formed on the inner wall of the connecting pipe (21) above the pressure relief hole (23). A piston hole (26) connecting the connecting pipe (21) and the interface (22) is formed in the valve shell (2) above the limiting protrusion ring (24). A piston (3) is inserted into the piston hole (26). A central countersunk hole (31) is formed on the lower end face of the piston (3). Several through-holes are formed on the inner wall of the upper end of the central countersunk hole (31). The outer wall of the plug (3) has a vent hole (33), and the outer end of the vent hole (33) is formed with a conical expansion hole (34). The inner wall of the piston hole (26) outside the expansion hole (34) is formed with a vent ring groove (27). The inner wall of the central countersunk hole (31) of the piston (3) is formed with an upper step groove (32) that penetrates the lower end face of the piston (3) and is annular. The inner wall of the upper part of the limiting convex ring (24) is formed with an annular lower step groove (25). Vertical pressure stabilizing springs (4) are inserted in the lower step groove (25) and the upper step groove (32). The upper and lower ends of the pressure stabilizing springs (4) press against the piston (3) and the limiting convex ring (24) respectively. A cylindrical annular pressure control sleeve (6) is inserted and fixed inside the interface (22) of the valve housing (2). The lower end of the pressure control sleeve (6) is formed with an L-shaped annular connection port (61). An inner sealing ring (7) is clamped and fixed between the outer wall of the lower end of the annular connection port (61) and the inner wall of the interface (22). The upper end of the piston (3) is formed with a conical sealing contact surface (35). The inner sealing ring (7) presses against the sealing contact surface (35) of the piston (3). A cylindrical filter element (20) is inserted inside the pressure control sleeve (6). The lower end of the filter element (20) abuts against the annular connection port (61) and the upper end abuts against the snap ring (30). The snap ring (30) is locked on the inner wall of the pressure control sleeve (6).

2. The pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine according to claim 1, characterized in that: The outer ring of the upper end of the connecting sleeve (13) is formed with a conical connecting surface, and the inner wall of the outer side of the valve shell (2) is a conical surface. The inner wall of the outer side of the valve shell (2) and the connecting surface on the connecting sleeve (13) are in the same conical surface. The outer sealing ring (10) is pressed against the inner wall of the outer side of the valve body (2), and a support ring (50) is sleeved on the lower part of the outer sealing ring (10). The support ring (50) is inserted and fixed on the valve seat (1).

3. The pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine according to claim 1, characterized in that: The external threaded connector (11) is fitted with an O-ring (60), and an annular groove is formed on the inner wall of the upper end of the external threaded connector (11). The O-ring (60) is inserted into the annular groove and pressed against the lower end face of the valve seat (1). The lower end of the external threaded connector (11) has an annular positioning groove (12) formed on its inner wall. The upper end of the pressure relief spring (8) is inserted into the positioning groove (12) of the external threaded connector (11) and pressed against the upper bottom surface of the positioning groove (12).

4. The pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine according to claim 1, characterized in that: An annular groove (28) is formed on the outer wall of the lower end of the connecting pipe (21), and an annular elastic retaining ring (70) is inserted in the groove (28). An annular connecting groove (91) is formed on the inner wall of the lower end of the limiting retaining ring (9). The elastic retaining ring (70) is inserted into the connecting groove (91) of the limiting retaining ring (9) and pressed against the limiting retaining ring (9).

5. The pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine according to claim 1, characterized in that: The upper end of the interface (22) is fixed with a positioning support sleeve (40), and the pressure control sleeve (6) is inserted and fixed in the positioning support sleeve (40). A retaining spring groove (62) is formed on the inner wall of the upper part of the pressure control sleeve (6), and the retaining spring (30) is inserted in the retaining spring groove (62) of the pressure control sleeve (6).

6. The pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine according to claim 1, characterized in that: The spring force of the stabilizing spring (4) is less than the spring force of the relief spring (8).

7. The pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine according to claim 1, characterized in that: The valve housing (2) has several pressure relief holes (29) connected to the pressure relief chamber (a) formed on the inner wall of the lower stepped groove (25). A valve core (80) with an inverted T-shaped cross section is inserted into the lower stepped groove (25). The lower end face of the valve core (80) presses against the bottom surface of the lower stepped groove (25). The outer wall of the lower end of the valve core (80) presses against the inner wall of the lower stepped groove (25) and covers the pressure relief holes (29). An air inlet hole is formed in the middle of the valve core (80). The air inlet hole consists of an upper conical guide hole (801) and a lower circular small hole (802). The diameter of the upper end of the guide hole (801) is smaller than the diameter of the small hole (802). The lower part of the pressure stabilizing spring (4) is sleeved on the valve core (80) and presses against the valve core (80). A drain hole (210) communicating with the pressure relief chamber (a) is formed on the outer wall of one side of the valve housing (2). A cylindrical annular internal threaded release port (211) is formed on the outer wall of the valve housing (2) at the outlet of the drain hole (210). A pressure-holding sleeve (100) is screwed into the internal threaded release port (211). A one-way valve plate (90) is clamped and fixed between the pressure-holding sleeve (100) and the valve housing (2). The one-way valve plate (90) covers the outlet of the drain hole (210).

8. A pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine according to claim 7, characterized in that: The one-way valve plate (90) includes a circular central valve plate (901) and an annular outer ring plate (902). The central valve plate (901) covers the drain hole (210) of the valve housing (2), and the outer ring plate (902) is clamped and fixed between the pressure sleeve (100) and the valve housing (2). A connecting piece (903) is formed between one side of the outer ring of the central valve plate (901) and the inner ring of the outer ring plate (902).

9. A pressure relief valve for a coolant reservoir in a water-cooled piston aircraft engine according to claim 7, characterized in that: Fiberglass sealing rings (5) are respectively embedded and fixed on the outer wall of the connecting pipe (21) on the upper side of the pressure relief hole (23) and the outer wall of the lower part of the valve core (80). The fiberglass sealing rings (5) are respectively pressed against the inner wall of the valve seat (1) and the inner wall of the lower step groove (25) of the valve body (2).

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