A safety pressure limiting valve for high pressure common rail of diesel engine

Abstract

The present invention discloses a safety pressure limiting valve for a high-pressure common rail of a diesel engine, comprising a valve body, a valve seat and a valve core, wherein a spring is installed at one end of the valve core through a spring seat, and a replaceable pressure regulating gasket is provided between the other end of the spring and the valve body. A limit mechanism for limiting the movement stroke of the valve core is provided between the valve body and the valve core, and a stabilizing pressure chamber and a high-pressure chamber that are internally connected are provided on the valve seat, and the valve core moves along the stabilizing pressure chamber and one end contacts one side of the stabilizing pressure chamber. An inner hole is provided on the valve core, and an overflow hole that is connected to the interior of the valve body is provided on one side of the inner hole, and a steel ball for sealing the inner hole is provided on one side of the spring seat, and a small hole that is connected to the inner hole and the stabilizing pressure chamber is provided at the lower end of the valve core. A valve body hole that is connected to the interior of the valve body is provided at the lower end of the valve body, and a low-pressure chamber that is connected to the valve body hole is provided on the common rail pipe.

Description

Technical Field

[0001] The invention relates to the technical field of diesel engine accessories, and in particular to a safety pressure limiting valve for a high-pressure common rail of a diesel engine. Background Art

[0002] In the diesel engine high-pressure common rail system, the fuel pressure in the high-pressure pipeline is relatively high. When the metering valve fails or the return oil of the high-pressure component is blocked or other abnormalities cause the rail pressure to be too high, it may cause damage to the system and even affect driving safety or personal safety.

[0003] Therefore, a valve is required to open and release the oil pressure in the above situation. The valve should not open under normal working pressure, but open to release the pressure to protect the common rail system when the system is abnormally high pressure. At the same time, the system oil pressure should be stabilized at a certain pressure after opening, and the injector should be continuously supplied with oil, so that the diesel engine can still work, so that the driver can take timely measures or drive the faulty vehicle to a service station for repair. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a safety pressure limiting valve for a high-pressure common rail of a diesel engine. The present invention can solve the problem of abnormally high pressure in the system and achieve the effect that the diesel engine can still work when the common rail system is under abnormally high pressure.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A safety pressure limiting valve for a high-pressure common rail of a diesel engine comprises a valve body, a valve seat and a valve core. A spring is installed at one end of the valve core through a spring seat, and a replaceable pressure regulating gasket is arranged between the other end of the spring and the valve body.

[0007] A limit mechanism for limiting the movement of the valve core is provided between the valve body and the valve core. A stabilizing pressure chamber and a high-pressure chamber which are internally connected are provided on the valve seat. The valve core moves along the stabilizing pressure chamber and one end contacts one side of the stabilizing pressure chamber.

[0008] An inner hole is formed on the valve core, an overflow hole communicating with the inside of the valve body is provided on one side of the inner hole, a steel ball for sealing the inner hole is provided on one side of the spring seat, and a small hole communicating with the inner hole and the stabilizing pressure chamber is provided at the lower end of the valve core.

[0009] The lower end of the valve body is provided with a valve body hole communicated with the interior thereof, and the common rail pipe is provided with a low-pressure chamber communicated with the valve body hole.

[0010] Furthermore, the upper diameter of the inner hole is larger than the lower diameter thereof, and the upper portion of the inner hole is a conical structure, and the steel ball contacts the conical structure to form a stable sealing ring line.

[0011] Furthermore, the diameter of the stabilizing pressure chamber is larger than the diameter of the lower part of the valve core, and a conical surface structure is provided on one side of the stabilizing pressure chamber, and the lower end of the valve core contacts the conical surface structure to form a high-pressure sealing loop.

[0012] Furthermore, the small hole is arranged to be inclined relative to the inner hole; a plurality of small holes are arranged, and are distributed in a circle with the axis of the valve core as the center.

[0013] Furthermore, the limiting mechanism includes a limiting step arranged at the lower inner part of the valve body, and the valve core is provided with a limiting shoulder that matches the limiting step.

[0014] Furthermore, a sealing ring is provided between the valve body and the common rail pipe.

[0015] Furthermore, the overflow holes include micropores and through holes.

[0016] The present invention has the beneficial effects:

[0017] 1. The present invention has a reasonable design and is easy to manufacture. When the valve core and the valve seat are closed, a leakage gap is formed between the stabilizing pressure chamber and the low-pressure chamber through the overflow hole to avoid long-term micro-leakage of the high-pressure sealing loop, resulting in a certain high-pressure fuel pressure in the stabilizing pressure chamber acting on the valve core, thereby preventing the valve core from opening at low pressure or opening before reaching a preset safety opening pressure, so that the system can work normally under the designed high pressure, which is beneficial to improving the reliability of the use of the safety pressure limiting valve.

[0018] 2. The present invention realizes two working performances through the design of the high-pressure sealing ring line between the valve core and the valve seat and the stabilizing sealing ring line between the steel ball and the valve core, namely, high-pressure opening safety protection and low-pressure stabilizing pressure constant, which makes the use more controllable and reliable.

[0019] 3. The present invention provides a limiting mechanism and a stabilizing pressure chamber on the valve core. After the valve core is opened under high pressure, a small gap is limited, that is, the valve core is lifted to a height that satisfies the gap with the maximum cross-sectional area of ​​oil flow at the high-pressure sealing loop line. The spring is less deformed by high-pressure impact, making the product performance more stable. The stabilizing pressure chamber drains oil through the inner hole of the valve core to achieve stabilizing performance by using a steel ball seal.

[0020] 4. When the overflow hole of the present invention is a structure combining micropores and through holes, a certain working pressure (i.e., stabilizing pressure) in the high-pressure storage device is provided for emergency operation of road vehicles, so that the motor vehicle can be driven to a repair shop for maintenance by itself.

[0021] 5. When the overflow hole of the present invention is a through hole structure, it is suitable for the common rail system of diesel engines for non-road construction machinery, and meets the technical requirements of diesel engine design. When in use, the structure allows the diesel engine opened at high pressure to maintain near the opening pressure. Under this pressure, the diesel engine can still work normally without power reduction, but it cannot work for a long time, and only meets the needs of the driver to take emergency measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a structural schematic diagram of embodiment 1;

[0023] Figure 2 It is a schematic diagram of the structure of the connection between the valve seat and the valve core in the first embodiment;

[0024] Figure 3 It is a schematic diagram of the structure of the connection between the valve seat and the valve core in the second embodiment;

[0025] Figure 4 is a pressure curve diagram when the first embodiment is used;

[0026] Figure 5 It is a pressure curve diagram when the second embodiment is used.

[0027] Description of reference numerals:

[0028] 1-valve body, 2-valve seat, 3-valve core, 4-steel ball, 5-spring seat, 6-spring, 7-pressure regulating gasket, 8-high-pressure chamber, 9-limit shoulder, 10-maintaining pressure chamber, 11-inner hole, 12-valve body hole, 13-low-pressure chamber, 14-overflow hole, 15-high-pressure sealing ring, 16-small hole, 17-maintaining sealing ring. DETAILED DESCRIPTION

[0029] In order to better understand the present invention, the present invention is further described below in conjunction with the accompanying drawings. It is worth noting that in the description of the present invention, the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0030] Example 1

[0031] A safety pressure limiting valve for a diesel engine high pressure common rail, such as Figure 1 As shown, it includes a valve body 1, a valve seat 2 and a valve core 3, and a sealing ring is provided between the valve body 1 and the common rail pipe. A spring 6 is installed at one end of the valve core 3 through a spring seat 5, and a replaceable pressure regulating gasket 7 is provided between the other end of the spring 6 and the valve body 1.

[0032] After the spring 6 is installed, the upper end surface contacts the pressure regulating gasket 7, and the lower end surface contacts the spring seat 5. After the pressure regulating gasket 7 is assembled with the valve body 1, there is no axial gap, and no bonding is required. It is pressed tightly by the spring force. Pressure regulating gaskets 7 of different thicknesses are assembled to change the pre-pressure of the spring 6 to achieve the required high-pressure opening pressure. The thicker the pressure regulating gasket 7, the more pre-compression of the spring 6, the greater the pre-pressure, and the higher the opening pressure of the valve.

[0033] like Figure 1 and Figure 2 As shown, a limiting mechanism for limiting the movement stroke of the valve core 3 is provided between the valve body 1 and the valve core 3, and the limiting mechanism includes a limiting step provided at the lower inner part of the valve body 1, and the diameter of the limiting step is larger than the diameter of the inner upper part of the valve body 1. A limiting shoulder 9 matching the limiting step is provided on the valve core 3, and the diameter of the limiting shoulder 9 is larger than the inner upper diameter of the valve body 1 and smaller than the inner diameter of the limiting step.

[0034] like Figure 1 and Figure 2 As shown, the valve seat 2 is provided with a stabilizing pressure chamber 10 and a high-pressure chamber 8 which are internally connected, and the valve core 3 moves along the stabilizing pressure chamber 10 and one end contacts one side of the stabilizing pressure chamber 10. The diameter of the stabilizing pressure chamber 10 is larger than the diameter of the lower part of the valve core 3, and a conical surface structure is provided on one side of the stabilizing pressure chamber 10, and the lower end of the valve core 3 contacts the conical surface structure to form a high-pressure sealing loop 15.

[0035] like Figure 2 As shown, the valve core 3 is provided with an inner hole 11, and the upper diameter of the inner hole 11 is larger than the lower diameter thereof. A steel ball 4 for sealing the inner hole 11 is provided on one side of the spring seat 5, and the upper part of the inner hole 11 is a conical structure, and the steel ball 4 contacts the conical structure and forms a stabilizing sealing ring line 17.

[0036] The force exerted by the spring 6 on the spring seat 5 acts on the valve core 3 through the steel ball 4 to form a closing force. The steel ball 4 and the valve core 3 are in close contact under the action of this force to form a stable sealing ring line 17. The force further acts on the valve seat 2, so that the valve core 3 and the valve seat 2 are in close contact at the seat surface to also form a high-pressure sealing ring line 15.

[0037] like Figure 2 As shown, the lower end of the valve core 3 is provided with a small hole 16 which is in communication with the inner hole 11 and the stabilizing pressure chamber 10. The small hole 16 is arranged obliquely relative to the inner hole 11; a plurality of small holes 16 are arranged and are distributed in a circle with the axis of the valve core 3 as the center.

[0038] like Figure 2As shown, one side of the inner hole 11 is provided with an overflow hole 14 communicating with the interior of the valve body 1, and the overflow hole 14 includes a micro hole and a through hole. The lower end of the valve body 1 is provided with a valve body hole 12 communicating with the interior thereof, and the common rail pipe is provided with a low pressure chamber 13 communicating with the valve body hole 12.

[0039] When the valve core 3 and the valve seat 2 are in the closed state, the stabilizing pressure chamber 10 and the low-pressure chamber 13 are connected through the overflow hole 14 to form a leakage gap to avoid long-term micro-leakage of the high-pressure sealing ring 15. A certain high-pressure fuel pressure is formed in the stabilizing pressure chamber 10 to act on the valve core 3, causing the valve core 3 to open upward, that is, avoiding low-pressure opening or opening before reaching the safe opening pressure designed by the system, so that the system can work normally under the designed high pressure.

[0040] The pressure of the high-pressure fuel in the high-pressure chamber 8 will form an upward hydraulic force on the surface below the high-pressure sealing ring line 15. Once the force exceeds the closing force of the spring 6 on the valve core 3, the valve core 3 will move upward to open. At this time, the high-pressure chamber 8 is connected to the stabilizing pressure chamber 10, and the pressure in the stabilizing pressure chamber 10 will increase rapidly, and then the pressure of the high-pressure fuel will act on a larger surface (guide diameter section) of the valve core 3, generating a larger upward hydraulic force, causing the valve core 3 to move upward until one side of the limit shoulder 9 contacts the limit step at the lower part of the valve body 1 and stops moving.

[0041] The guide diameter section of the valve core 3 is equivalent to the cross-sectional area of ​​the guide diameter of the valve core 3, that is, the pressure oil pressure bearing area. The pressure oil acts on the entire surface of the head of the valve core 3, and the upward force generated is proportional to the cross-sectional area of ​​the guide diameter.

[0042] Next, the high-pressure fuel in the stabilizing pressure chamber 10 is connected to the inner hole 11 through the four small holes 16 on the valve core 3, so that the pressure of the high-pressure fuel further acts on the surface of the steel ball 4 below the stabilizing sealing ring line 17. The fuel liquid pressure on the surface of the steel ball 4 is greater than the closing force of the spring 6 at this time, so that the steel ball 4 moves upward and opens, and the high-pressure fuel overflows into the inner cavity of the valve body 1. The inner cavity of the valve body 1 is connected to the low-pressure chamber 13 through the valve body hole 12, and the overflowed fuel enters the low-pressure chamber 13 through the valve body hole 12 and is guided back to the fuel tank. A large amount of high-pressure fuel overflows, causing the fuel pressure in the high-pressure chamber to drop, thereby protecting the system pressure safety.

[0043] Moreover, the stabilizing pressure chamber 10 is connected with the high-pressure chamber 8. This pressure must overcome the closing force of the spring 6 to open the steel ball 4 for overflow. Therefore, by designing the diameter of the stabilizing sealing ring line 17 at the steel ball 4 and the valve core 3 to determine the force area of ​​the steel ball 4, different stabilizing pressures can be formed to meet the requirements of different diesel engine systems.

[0044] That is to say, when the system exceeds the predetermined pressure, that is, overcomes the closing force of the spring 6, so that the steel ball 4 no longer seals the inner hole 11, the valve is opened, and the high-pressure oil flows into the low-pressure chamber 13 through the inner hole 11 in the valve core 3 and the valve body hole 12, causing the pressure in the high-pressure chamber 8 to drop rapidly.

[0045] Under the action of the predetermined spring force, the overflow flow is controlled at the stabilizing seal ring 17 between the steel ball 4 and the valve core 3 to achieve the system stabilizing pressure. At this time, the high pressure chamber 8 is connected to the low pressure chamber 13, and the oil flow channel gap is adjusted by the overflow hole 14 according to the balance between the oil pressure and the spring force.

[0046] The device is installed on the high-pressure storage device and provides a certain working pressure (i.e., stabilizing pressure) in the high-pressure storage device for emergency operation of road vehicles, so that the motor vehicle can be driven to the repair shop for maintenance by itself.

[0047] When using this device, Figure 4 As shown, it describes the protection of diesel engine fault pressure increase, that is, high pressure opening pressure. The sudden drop curve is the process curve of the device from high pressure opening to low pressure stabilization pressure, so as to achieve low pressure stabilization operation.

[0048] Specifically, after the device is opened at high pressure, the pressure drops rapidly, and the stabilizing seal ring line 17 at the steel ball 4 forms a secondary seal. At this time, the stabilizing pressure chamber 10 is connected with the high pressure chamber 8, and the flow of the overflow hole 14 can be ignored. The surface of the steel ball 4 below the stabilizing seal ring line 17 is the force surface, and the liquid pressure acting on this surface and the closing force of the spring 6 form a dynamic balance, so that the pressure drops rapidly and then stabilizes at a lower pressure level. The diesel engine can still work at this pressure, but the power is insufficient and can only meet the driver's needs to drive the vehicle to the maintenance station.

[0049] Example 2

[0050] Based on Example 1, for the common rail system of a non-road diesel engine of an engineering machinery, the following can be adopted according to the design technical requirements of the diesel engine: Figure 3 In the overflow hole 14 structure shown, the overflow hole 14 is only provided with a through hole portion.

[0051] Compared with the micropore + through hole structure of the overflow hole 14 in Example 1, no micropore is provided in this embodiment, but a through hole with a large diameter is made to form a large flow channel. The purpose is not to overflow and maintain stability through the maintenance sealing ring line 17 between the steel ball 4 and the valve core 3, but to overflow and maintain stability at the high-pressure sealing ring line 15 between the valve core 3 and the valve seat 2.

[0052] When using, Figure 5 As shown, the diesel engine described performs alarm pressure protection after the high pressure is turned on.

[0053] That is, the overflow hole 14 on the valve core 3 connects the inner cavity of the valve seat 1, the low-pressure chamber 13 and the stabilizing pressure chamber 10 to form a low-pressure channel. After the device is opened at high pressure, the secondary seal of the stabilizing sealing ring line 17 at the steel ball 4 does not work. At this time, the surface of the valve core 3 below the high-pressure sealing ring line 15 at the valve core 3 and the valve seat 2 is still a force-bearing surface, and this force-bearing surface is much smaller than the force-bearing surface of the steel ball 4 in Example 1. The liquid pressure acting on this surface and the closing force of the spring 6 form a dynamic balance. This pressure is the same as the opening pressure of the device (the force-bearing area has not changed), so the system pressure does not drop, but directly stabilizes near the opening pressure. Under this pressure, the diesel engine can still work normally, and the power does not drop, but it cannot work for a long time, and only meets the driver's needs to take emergency measures.

Claims

1. A safety pressure limiting valve for a diesel engine high pressure common rail, comprising a valve body, a valve seat and a valve core, characterized in that: A spring is installed at one end of the valve core through a spring seat, and a replaceable pressure regulating gasket is provided between the other end of the spring and the valve body; A limit mechanism for limiting the movement of the valve core is provided between the valve body and the valve core, a stabilizing pressure chamber and a high-pressure chamber which are internally connected are provided on the valve seat, and the valve core moves along the stabilizing pressure chamber and one end of the valve core contacts one side of the stabilizing pressure chamber; An inner hole is formed on the valve core, an overflow hole communicating with the inside of the valve body is provided on one side of the inner hole, a steel ball for sealing the inner hole is provided on one side of the spring seat, and a small hole communicating with the inner hole and the stabilizing pressure chamber is provided at the lower end of the valve core; The lower end of the valve body is provided with a valve body hole communicating with the interior thereof, and the common rail pipe is provided with a low-pressure chamber communicating with the valve body hole; The upper diameter of the inner hole is larger than the lower diameter, and the upper part of the inner hole is a conical structure, and the steel ball contacts the conical structure to form a stable sealing loop; The diameter of the stabilizing pressure chamber is larger than the diameter of the lower part of the valve core, and a conical surface structure is provided on one side of the stabilizing pressure chamber, and the lower end of the valve core contacts the conical surface structure to form a high-pressure sealing loop; The limiting mechanism comprises a limiting step arranged at the lower part of the valve body, and the valve core is provided with a limiting shoulder matched with the limiting step.

2. A safety pressure limiting valve for a diesel engine high pressure common rail according to claim 1, characterized in that: The small hole is arranged to be inclined relative to the inner hole; a plurality of small holes are arranged and are distributed in a circle with the axis of the valve core as the center.

3. A safety pressure limiting valve for a diesel engine high pressure common rail according to claim 1, characterized in that: A sealing ring is arranged between the valve body and the common rail pipe.

4. A safety pressure limiting valve for a diesel engine high pressure common rail according to claim 1, characterized in that: The overflow holes include micropores and through holes.

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