A fuel injector with integrated flow limiting function

Abstract

This invention relates to an injector with integrated flow-limiting function, comprising a screw plug, an injector body, an upper spring seat, a fixed spring, a valve core, a pressure sleeve, a lower spring seat, and a flow-limiting spring. The injector body has an inlet passage, an outlet passage, a threaded hole, a first hole, a first sealing cone surface, a second bevel, a second hole, a third hole, a fourth hole, a fifth hole, and a sixth hole. The second, third, fourth, fifth, and sixth holes form a pressure accumulator. The inlet and outlet passages are interconnected with the pressure accumulator. A flow-limiting spring, a valve core, and a lower spring seat are sequentially installed at the bottom of the pressure accumulator. The lower spring seat has a first pressing surface, a fourth central hole, an installation bevel, and a first central hole. The valve core passes through the fourth central hole and is pressed against the first pressing surface. The installation bevel of the lower spring seat is pressed against the second bevel of the injector body by the fixed spring. One end of the fixed spring is fixed inside the first central hole, and the other end is fixed to the upper spring seat. A pressure sleeve and a screw plug are sequentially fixed to the upper spring seat.

Description

Technical Field

[0001] This invention relates to the field of high-pressure common rail fuel system technology for diesel engines, specifically to an injector with integrated flow limiting function. Background Technology

[0002] Flow control valves are commonly used in common rail systems. On the one hand, they reduce rail pressure fluctuations, and on the other hand, they allow the injectors to automatically stop injecting when the injector is over-injected, thereby reducing contaminants and minimizing machine damage.

[0003] Ordinary flow restrictors undergo linear reciprocating motion during operation, but because they cannot rotate on their own, they cannot be adapted to single-sided oil inlet designs. Summary of the Invention

[0004] This invention provides an injector with integrated flow limiting function, which enables the injector to achieve integrated flow limiting function, and an injector adapted to a single-sided oil inlet design.

[0005] The technical solution of this application is as follows:

[0006] This application provides an injector with integrated flow limiting function, including: an injector body and a pressure sleeve, an upper spring seat, a fixed spring, a lower spring seat, a valve core, and a flow limiting spring installed in the accumulator chamber of the injector body;

[0007] The injector body also includes an inlet passage and an outlet passage that communicate with the accumulator chamber;

[0008] The pressure sleeve is fixed in the pressure accumulator chamber;

[0009] The upper spring seat, the fixed spring, and the lower spring seat are sequentially assembled below the pressure sleeve;

[0010] One end of the valve core extends movably into the lower spring seat from below;

[0011] The flow-limiting spring is disposed between the valve core and the bottom of the accumulator chamber; the valve core is provided with a spiral groove in the circumferential direction;

[0012] When the injector starts injecting fuel and the injection amount does not exceed the set amount, the fuel enters the lower spring seat through the fuel inlet and the accumulator. Under the action of downward hydraulic pressure, the valve core moves towards the flow-limiting spring. The fuel that enters the lower spring seat flows downward through the spiral groove into the fuel outlet.

[0013] When the injector is not injecting fuel, the valve core is pressed tightly against the lower spring seat under the upward force of the flow-limiting spring.

[0014] When the fuel injection quantity of the injector exceeds the set quantity, a seal is formed between the valve core and the cavity wall of the accumulator, preventing the fuel entering the lower spring seat from flowing out through the fuel outlet.

[0015] Preferably, the lower spring seat is provided with a first central hole, a second central hole, a third central hole and a fourth central hole in sequence;

[0016] The lower spring seat is also provided with an oil inlet that connects the accumulator chamber and the second central hole;

[0017] The diameter of the third central hole is smaller than that of the fourth central hole, so that the fourth central hole forms a first pressing surface for pressing the valve core on the side close to the third central hole.

[0018] When the injector is not injecting oil, one end of the valve core passes through the fourth and third central holes and extends into the second central hole. Under the upward force of the flow-limiting spring, the valve core is pressed against the first pressing surface of the fourth central hole.

[0019] Preferably, the pressure accumulator includes a second hole, a third hole, a fourth hole, a fifth hole, and a sixth hole arranged from top to bottom;

[0020] The second hole and the third hole are connected by a first bevel, and the third hole and the fourth hole are connected by a second bevel;

[0021] The oil inlet passage is connected to the third hole, the fourth hole and the fifth hole are connected by a second sealing cone surface, the fifth hole is connected to the oil outlet passage, and the fifth hole is connected to the sixth hole;

[0022] The lower spring seat is arranged in the third hole, and the mounting angle of the lower spring seat is pressed against the second angle.

[0023] Preferably, the side of the lower spring seat is provided with an annular groove, the inlet of the oil inlet hole is arranged in the groove, the groove and the hole wall of the third hole are opposite to each other, so that the fuel entering through the oil inlet passage enters the groove, and then enters the second middle hole through the oil inlet hole connected to the groove.

[0024] The recess is set between the first outer circle and the second outer circle of the lower spring seat, and the outer diameters of the first outer circle and the second outer circle are the same.

[0025] Preferably, the valve core includes: a guide portion and a balance shaft connected together, wherein the outer diameter of the guide portion is larger than the outer diameter of the balance shaft;

[0026] An oil groove is provided on the second pressing surface that connects the guide part to the balance shaft, and a spiral groove that communicates with the oil groove is provided on the outer periphery of the guide part;

[0027] A third sealing cone surface is formed on the side of the guide section facing the current-limiting spring;

[0028] The outer diameter of the balance shaft is smaller than the diameter of the third central hole. When the valve core moves to make the second pressing surface and the first pressing surface fit together, the spiral groove is connected to the third central hole through the oil groove.

[0029] When the fuel injection quantity of the injector exceeds the set quantity, a seal is formed between the third sealing cone surface and the second sealing cone surface, preventing the fuel entering the lower spring seat from flowing out through the fuel outlet.

[0030] Preferably, the injector body further includes a first hole communicating with the second hole and a threaded hole communicating with the first hole;

[0031] The first hole and the second hole are connected by a first sealing conical surface;

[0032] The injector also includes: a screw plug;

[0033] The head of the plug passes through the threaded hole and the first hole and then fits against the first sealing cone surface, and the plug is threadedly connected to the threaded hole.

[0034] One end of the pressure sleeve is fixed inside the countersunk hole of the screw plug, and the other end is pressed against the upper spring seat.

[0035] Preferably, the lift h of the valve core is less than the length of the guide portion and less than the length of the fourth central hole;

[0036] The flow area of ​​the spiral groove is smaller than the flow area of ​​the oil trough;

[0037] The diameter of the guide portion is the same as the diameter of the fourth central hole, and the guide portion and the fourth central hole are fitted with a clearance, allowing the valve core to slide freely within the lower spring seat.

[0038] Preferably, a stress-reducing groove is provided on the wall of the fourth hole, and the stress-reducing groove is located in connection with the first pressing surface.

[0039] Preferably, one end of the flow-limiting spring is fixed to the bottom surface of the sixth hole, and the other end passes through the fifth and fourth holes and is fixed in the spring hole provided on the valve core.

[0040] Preferably, the pressure sleeve includes a mating part that is clearance-fitted with the second hole.

[0041] The beneficial effects of this application are as follows:

[0042] By incorporating an accumulator chamber within the injector body, the injector body functions as a common rail, simplifying the components. Furthermore, the components responsible for the flow restrictor function are installed within the accumulator chamber, saving space previously occupied by the external flow restrictor. The placement of these components near the injection end further reduces pressure fluctuations. During injector operation, the spiral groove design allows the valve core to rotate while moving linearly, better adapting to single-sided inlet designs and ensuring reliability. Fuel filling the spiral grooves also provides self-lubrication to the valve core, reducing the risk of jamming and resulting in faster response. Attached Figure Description

[0043] Figure 1 This is one of the structural schematic diagrams of an injector with integrated flow limiting function according to an embodiment of the present invention;

[0044] Figure 2 This is a second schematic diagram of the structure of an injector with integrated flow limiting function according to an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of the injector body according to an embodiment of the present invention;

[0046] Figure 4 This is a schematic diagram of the lower spring seat according to an embodiment of the present invention;

[0047] Figure 5 This is a schematic diagram of the valve core structure according to an embodiment of the present invention;

[0048] Figure 6 This is a schematic diagram of the valve core structure according to an embodiment of the present invention;

[0049] Figure 7 This is a schematic diagram of the pressure sleeve according to an embodiment of the present invention;

[0050] Figure 8 This is a schematic diagram of the pressure sleeve according to an embodiment of the present invention;

[0051] Explanation of reference numerals in the attached figures:

[0052] 1—Injector body;

[0053] 101—Threaded hole; 102—First hole; 103—First sealing cone surface; 104—Second hole; 105—First bevel angle; 106—Third hole; 107—Second bevel angle; 108—Oil inlet passage; 109—Fourth hole; 110—Second sealing cone surface; 111—Oil outlet passage; 112—Fifth hole; 113—Sixth hole;

[0054] 2—Upper spring seat; 3—Fixed spring; 4—Lower spring seat;

[0055] 401—First central hole; 402—Second central hole; 403—Oil inlet; 404—Third central hole; 405—First pressing surface; 406—Strain relief groove; 407—Fourth central hole; 408—First outer circle; 409—Counter groove; 410—Second outer circle; 411—Third outer circle; 412—Installation bevel;

[0056] 5—Valve core;

[0057] 501—Balance shaft; 502—Second clamping surface; 503—Oil groove; 504—Helical groove; 505—Guide part; 506—Positioning circle; 507—Third sealing cone surface; 508—Spring hole;

[0058] 6—current limiting spring; 7—pressure sleeve;

[0059] 701—First balance hole; 702—Second balance hole; 703—Third balance hole; 704—Through hole; 706—Matching part; 8—Plug. Detailed Implementation

[0060] like Figure 1 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, an injector with integrated flow limiting function includes an injector body 1, a lower spring seat 4, a valve core 5, a flow limiting spring 6, a pressure sleeve 7, and a screw plug 8.

[0061] Reference Figure 3 The injector body 1 is provided with a pressure accumulator chamber and an oil inlet passage 108 and an oil outlet passage 111 connected to the pressure accumulator chamber.

[0062] Specifically, holes are made on the upper surface of the injector body 1, forming a first hole 102, a second hole 104, a third hole 106, a fourth hole 109, a fifth hole 112 and a sixth hole 113 from top to bottom; the second hole 104, the third hole 106, the fourth hole 109, the fifth hole 112 and the sixth hole 113 together form the aforementioned pressure accumulator chamber.

[0063] Reference Figure 3 The first hole 102 and the second hole 104 are connected by the first sealing cone surface 103. The second hole 104 and the third hole 106 are connected by the first oblique angle 105. The third hole 106 and the fourth hole 109 are connected by the second oblique angle 107. The oil inlet passage 108 is connected to the third hole 106. The fourth hole 109 and the fifth hole 112 are connected by the second sealing cone surface 110. The fifth hole 112 is connected to the oil outlet passage 111. The fifth hole 112 is connected to the sixth hole 113.

[0064] Combination Figures 1 to 4 The lower spring seat 4 is assembled in the third hole 106, and its lower part is pressed against the second oblique angle 107.

[0065] Reference Figure 4 The upper surface of the lower spring seat 4 has openings, forming a first central hole 401, a second central hole 402, a third central hole 404, and a fourth central hole 407 from top to bottom.

[0066] Reference Figure 2 and 4 An oil inlet hole 403 is provided on the side of the lower spring seat 4, which is connected to the second intermediate hole 402. An annular groove 409 is provided on the side of the lower spring seat 4, and the inlet of the oil inlet hole 403 is arranged in the groove 409. The walls of the groove 409 and the third hole 106 are opposite to each other, so that the fuel entering through the oil inlet passage 108 enters the groove 409, and then enters the second intermediate hole 402 through the oil inlet hole 403 connected to the groove 409.

[0067] Combination Figure 2 The fuel entering the second central hole 402 flows upward through the first central hole 401 into the second hole 104 above the lower spring seat 4, and downward through the third central hole 404 into the fourth central hole 407.

[0068] Reference Figure 4 The recess 409 is set between the first outer circle 408 and the second outer circle 410 of the lower spring seat 4, and the outer diameters of the first outer circle 408 and the second outer circle 410 are the same.

[0069] Reference Figure 2 and Figure 4 The diameter of the third central hole 404 is smaller than that of the fourth central hole 407, which causes the fourth central hole 407 to form a first pressing surface 405 for pressing the valve core 5 on the side near the third central hole 404.

[0070] Reference Figure 4 The lower spring seat 4 is also provided with a stress-reducing groove 406 on the wall of the fourth central hole 407. The stress-reducing groove 406 is provided in connection with the first pressing surface 405 to prevent the second pressing surface 502 of the valve core from interfering with the first pressing surface 405.

[0071] Reference Figure 2 One end of the valve core 5 passes through the fourth central hole 407 and the third central hole 404 of the lower spring seat 4 and then extends into the second central hole 402.

[0072] Reference Figure 5 and Figure 6The valve core 5 includes: a guide portion 505 and a balance shaft 501 connected together. The outer diameter of the guide portion 505 is larger than the outer diameter of the balance shaft 501. An oil groove 503 is provided on the second pressing surface 502 where the guide portion 505 is connected to the balance shaft 501. A spiral groove 504 is provided on the outer periphery of the guide portion 505. A spring hole 508 is provided on the end face of the guide portion 505 facing the flow limiting spring 6. A positioning outer circle 506 is formed on the side of the guide portion 505 facing the flow limiting spring 6. A third sealing cone surface 507 is formed between the end faces of the positioning outer circle 506 facing the flow limiting spring 6.

[0073] The fuel in the spiral groove 504 applies a lateral force to the valve core 5, causing the valve core 5 to rotate around its own center while performing linear reciprocating motion.

[0074] Reference Figure 5 and Figure 6 The outer diameter of the balance shaft 501 is smaller than the diameter of the third central hole 404. When the valve core 5 moves to the state where the second pressing surface 502 and the first pressing surface 405 are in contact, the spiral groove 504 is connected to the third central hole 404 through the oil groove 503. The fuel in the spiral groove 504 enables the valve core 5 to self-lubricate and move more smoothly.

[0075] Reference Figure 2 and Figure 3 One end of the flow-limiting spring 6 is fixed to the bottom surface of the sixth hole 113, and the other end passes through the fifth hole 112 and the fourth hole 109 and is fixed in the spring hole 508 of the valve core 5.

[0076] Reference Figure 1 and Figure 3 After the head of the screw plug 8 passes through the threaded hole 101 and the first hole 102, it fits against the first sealing cone surface 103, and the screw plug 8 is threadedly connected to the threaded hole 101.

[0077] Reference Figure 1 , Figure 7 and Figure 8 The pressure sleeve 7 is in the second hole 104 of the accumulator chamber, with one end passing through and the other end fixed in the countersunk hole of the screw plug 8, and the other end pressed against the upper spring seat 2.

[0078] Reference Figure 2 The upper spring seat 2 is located in the second hole 104 of the accumulator chamber and is pressed against the pressure sleeve 7 by the fixing spring 3.

[0079] Reference Figure 2 The fixed spring 3 is located in the second hole 104 of the accumulator chamber, with one end connected to the bottom of the first middle hole 401 of the lower spring seat 4, and the other end fixedly connected to the upper spring seat 2.

[0080] like Figure 2 and Figure 3As shown, the full angle of the first oblique angle 105 is designed to be less than 20°, which facilitates the installation of the lower spring seat 4 and can play a guiding role for the lower spring seat 4, making the installation smoother.

[0081] like Figure 2 , Figure 6 and Figure 7 As shown, the pressure sleeve 7 includes a mating part 706, which is clearance-fitted with the second hole 104. When the pressure sleeve 7 is pressed against the upper spring seat 2, the mating part 706 engages with the second hole 104, ensuring that the center error between the pressure sleeve 7 and the center of the second hole 104 is minimized, the force applied to the spring seat 2 is balanced, and no lateral force is generated. Furthermore, the lower spring seat 4 can be better fixed.

[0082] In the initial state (i.e., before the injector starts injecting fuel), no fuel enters from the fuel inlet passage 108. For the lower spring seat 4, it is only subjected to the downward force applied by the fixed spring 3, which causes the mounting angle 412 of the lower spring seat 4 to press against the second angle 107 of the injector body 1; for the valve core 5, due to the upward force applied by the flow-limiting spring 6, the second pressing surface 502 of the valve core 5 and the first pressing surface 405 of the lower spring seat 4 are in contact.

[0083] When the injector starts injecting fuel but the amount of fuel injected does not exceed the set amount of fuel injected, the fuel enters from the fuel inlet 108 into the gap between the wall of the third hole 106 and the sink 409. Since the first outer circle 408 and the second outer circle 410 of the lower spring seat 4 have the same diameter, the fuel in the sink 409 exerts the same force on the first outer circle 408 and the second outer circle 410, so that the lower spring seat 4 is in a balanced state.

[0084] The fuel entering the sink 409 will further pass through the oil inlet 403 of the lower spring seat 4 and enter the second central hole 402 of the lower spring seat 4. Then the fuel flows into the following two oil paths: one is that the fuel in the second central hole 402 passes through the first central hole 401, the second hole 104, and the central hole of the upper spring seat 2 into the through hole 704 of the pressure sleeve 7, and then passes through the first balance hole 701, the second balance hole 702, and the third balance hole 703 of the pressure sleeve 7, and finally reaches the first cavity formed between the mating part 706 of the pressure sleeve 7 and the wall of the second hole 104; the other is that the fuel in the first central hole 402 passes through the third central hole 404, the fourth central hole 407, the oil groove 503, and the spiral groove 504 and flows into the fourth hole 109, the fifth hole 112, and the sixth hole 113, and finally enters the other components of the injector through the oil outlet 111 connected by the fifth hole 112. At this time, the downward force on the lower spring seat 4 includes not only the downward force applied by the fixing spring 3, but also the downward hydraulic pressure applied by the fuel in the third hole 106; the upward force on the lower spring seat 4 comes from the upward hydraulic pressure applied by the fuel in the fourth hole 109. Because the diameter of the third hole 106 is larger than the diameter of the fourth hole 109, the downward hydraulic pressure on the lower spring seat 4 is greater than the upward hydraulic pressure, so that the mounting angle 412 of the lower spring seat 4 can be well pressed against the second angle 107 of the injector body 1.

[0085] like Figure 4 As shown, the oil inlet 403 of the lower spring seat 4 consists of four holes of equal diameter. The four oil inlet holes 403 are evenly distributed on the cylindrical surface of the second central hole 402 along the axial direction of the lower spring seat 4. The four oil inlet holes 403 are symmetrically distributed relative to the center to reduce the lateral force on the fixing of the lower spring seat 4. Similarly, the oil groove 503 of the valve core 5 is also designed as two symmetrically distributed square grooves, and the first balance hole 701, second balance hole 702, and third balance hole 703 on the pressure sleeve 7 are all designed in a centrally symmetrical distribution form, thereby reducing the influence of fuel on the lateral force of the parts.

[0086] like Figure 1 As shown in the embodiments of this application, the working process of the fuel injector mainly consists of three stages:

[0087] The first stage is the initial state, at which time the injector does not inject oil. Due to the spring force applied to the valve core 5 by the flow limiting spring 6, the first pressing surface 405 of the lower spring seat 4 is tightly pressed against the second pressing surface 502 of the valve core 5; and at this time, the lift h of the valve core 5 is 0.

[0088] The second stage occurs when the injector starts injecting fuel and the injection amount does not exceed the set injection amount. Under the action of downward hydraulic pressure, the valve core 5 moves towards the flow-limiting spring 6. At this time, the lift h of the valve core 5 is between 0 and the set value. When the injector stops injecting fuel, the lift h of the valve core 5 will decrease. As long as the interval between two injections of the injector is long enough, the lift h of the valve core 5 will eventually become 0. At the instant when the lift h of the valve core 5 is 0, the first pressing surface 405 of the lower spring seat 4 impacts the second pressing surface 502. At this time, the stress-reducing groove 406 provided on the lower spring seat 4 can make the second pressing surface 502 and the first pressing surface 405 fit tightly together, and can also reduce the stress effect caused by the impact of the first pressing surface 405 and the second pressing surface 502. During this process, the valve core 5 performs linear reciprocating motion.

[0089] The third stage occurs when the injector's fuel injection quantity exceeds the set injection quantity. Under downward hydraulic pressure, the valve core 5 moves towards the flow-limiting spring 6 until the third sealing cone surface 507 of the valve core 5 presses against the second sealing cone surface 110 of the injector body 1. Figure 2 As shown, at this time, the oil passage of the accumulator is blocked, there is no fuel in the oil outlet 111, and the injector does not inject fuel.

[0090] In this embodiment, during the movement of the valve core 5, the fuel in the guide portion 505 of the valve core 5 will apply a lateral force to the valve core 5 due to the spiral groove 504 provided on it. This allows the valve core 5 to rotate around its own center while performing linear reciprocating motion.

[0091] In this embodiment, the oil outlet 111 is located on the side of the injector body. When the injection quantity exceeds the set injection quantity, the third sealing cone surface 507 of the valve core 5 presses against the second sealing cone surface 110. Due to the laterally distributed oil outlets 111, the force on the third sealing cone surface 507 of the valve core 5 is uneven, resulting in uneven force pressing against the second sealing cone surface 110. If the valve core 5 itself does not rotate, the point at which the valve core 5 impacts the second sealing cone surface 110 is the same each time. This situation easily leads to fatigue at a certain point, reducing service life. However, in this embodiment, since the valve core 5 can rotate while performing linear motion, the point at which the third sealing cone surface 507 impacts the second sealing cone surface 110 is different each time, reducing fatigue points and increasing service life. Figure 1 , Figure 5 and Figure 6 The diameter of the guide portion 505 shown is the same as the diameter of the fourth central hole 407 of the lower spring seat 4. The guide portion 505 and the fourth central hole 407 are fitted with a clearance, so that the valve core 5 can slide freely in the lower spring seat 4.

[0092] Furthermore, because the flow area of ​​the spiral groove 504 on the valve core 5 is smaller than that of the oil groove 503, the spiral groove 504 functions as a throttling orifice. When the injection quantity exceeds the set injection quantity, due to the presence of the spiral groove 504, the fuel in the second cavity reaches the fourth hole 109 after passing through the spiral groove 504. Since the flow area of ​​the spiral groove 504 can meet the normal injection requirements, the valve core 5 will move towards the flow-limiting spring 6 to compensate for the reduced injection quantity. After the injection quantity exceeds the set injection quantity, the fuel passing through the spiral groove 504 is insufficient to compensate for the reduced injection quantity. At this time, the valve core 5 compensates for the reduced injection quantity by moving towards the flow-limiting spring 6 until the valve core 5 closes. In addition to its functions as an oil passage and throttling orifice, the spiral groove 504 also serves as a lubricant, allowing the valve core 5 to operate smoothly within the lower spring seat 4. Since the lift h of valve core 5 is less than the length of guide portion 505 and less than the length of fourth central hole 407, even if the lift h of valve core 5 is at the set maximum value, the guide portion 505 of valve core 5 is still inside the fourth central hole 407 of lower spring seat 4, which facilitates guidance when valve core 5 returns to its original position and makes it less prone to jamming.

Claims

1. A fuel injector with integrated flow limiting function, characterized in that, include: Injector body (1) and pressure sleeve (7), upper spring seat (2), fixed spring (3), lower spring seat (4), valve core (5) and flow limiting spring (6) installed in the accumulator chamber of the injector body (1); The injector body (1) also includes an oil inlet passage (108) and an oil outlet passage (111) that are connected to the accumulator chamber. The pressure sleeve (7) is fixed in the pressure accumulator cavity; The upper spring seat (2), the fixed spring (3) and the lower spring seat (4) are sequentially assembled below the pressure sleeve. One end of the valve core (5) extends movably into the lower spring seat (4) from below; The flow-limiting spring (6) is disposed between the valve core (5) and the bottom of the accumulator chamber; the valve core (5) is provided with a spiral groove (504) in the circumferential direction. When the injector starts injecting fuel and the amount of fuel injected does not exceed the set amount, the fuel enters the lower spring seat (4) through the fuel inlet (108) and the accumulator chamber. The valve core (5) moves toward the flow limiting spring (6) under the action of downward hydraulic pressure. The fuel that enters the lower spring seat (4) flows downward through the spiral groove (504) into the fuel outlet (111). When the injector is not injecting oil, the valve core (5) is pressed against the lower spring seat (4) under the upward force of the flow limiting spring (6); When the amount of fuel injected by the injector exceeds the set amount, a seal is formed between the valve core (5) and the cavity wall of the accumulator, blocking the fuel entering the lower spring seat (4) from flowing out through the oil outlet (111).

2. The injector with integrated flow limiting function according to claim 1, characterized in that, The lower spring seat (4) is provided with a first central hole (401), a second central hole (402), a third central hole (404) and a fourth central hole (407) in sequence. The lower spring seat (4) is also provided with an oil inlet (403) that connects the accumulator chamber and the second middle hole (402). The diameter of the third central hole (404) is smaller than that of the fourth central hole (407), so that the fourth central hole (407) has a first pressing surface (405) for the valve core (5) to be pressed on the side of the third central hole (404). When the injector is not injecting oil, one end of the valve core (5) extends into the second central hole (402) through the fourth central hole (407) and the third central hole (404), and the valve core (5) is pressed against the first pressing surface (405) of the fourth central hole (407) under the upward force of the flow limiting spring (6).

3. The injector with integrated flow limiting function according to claim 2, characterized in that, The pressure accumulator includes a second hole (104), a third hole (106), a fourth hole (109), a fifth hole (112), and a sixth hole (113) arranged from top to bottom. The second hole (104) and the third hole (106) are connected by a first bevel (105), and the third hole (106) and the fourth hole (109) are connected by a second bevel (107). The oil inlet channel (108) is connected to the third hole (106), the fourth hole (109) and the fifth hole (112) are connected by the second sealing cone surface (110), the fifth hole (112) is connected to the oil outlet channel (111), and the fifth hole (112) is connected to the sixth hole (113). The lower spring seat (4) is arranged in the third hole (106), and the mounting angle (412) of the lower spring seat (4) is pressed against the second angle (107).

4. The injector with integrated flow limiting function according to claim 3, characterized in that, The lower spring seat (4) has an annular groove (409) on its side. The inlet of the oil inlet hole (403) is arranged in the groove (409). The walls of the groove (409) and the third hole (106) are opposite to each other, so that the fuel entering through the oil inlet passage (108) enters the groove (409) and then enters the second middle hole (402) through the oil inlet hole (403) which is connected to the groove (409). The groove (409) is set between the first outer circle (408) and the second outer circle (410) of the lower spring seat (4), and the outer diameters of the first outer circle (408) and the second outer circle (410) are the same.

5. The injector with integrated flow limiting function according to claim 3, characterized in that, The valve core (5) includes: a guide portion (505) and a balance shaft (501) connected together, wherein the outer diameter of the guide portion (505) is larger than the outer diameter of the balance shaft (501); An oil groove (503) is provided on the second pressing surface (502) where the guide part (505) is connected to the balance shaft (501), and a spiral groove (504) communicating with the oil groove (503) is provided on the outer periphery of the guide part (505). A third sealing cone surface (507) is formed on the side of the guide portion (505) facing the current limiting spring (6); The outer diameter of the balance shaft (501) is smaller than the diameter of the third central hole (404). When the valve core (5) moves to make the second pressing surface (502) and the first pressing surface (405) stick together, the spiral groove (504) is connected to the third central hole (404) through the oil groove (503). When the amount of fuel injected by the injector exceeds the set amount, a seal is formed between the third sealing cone (507) and the second sealing cone (110), blocking the fuel entering the lower spring seat (4) from flowing out through the oil outlet (111).

6. The injector with integrated flow limiting function according to claim 3, characterized in that, The injector body also includes a first hole (102) communicating with the second hole (104) and a threaded hole (101) communicating with the first hole (102). The first hole (102) and the second hole (104) are connected by a first sealing cone surface (103); The injector also includes: a screw plug (8); The head of the plug (8) passes through the threaded hole (101) and the first hole (102) and then fits against the first sealing cone surface (103). The plug (8) is threadedly connected to the threaded hole (101). One end of the pressure sleeve (7) is fixed in the countersunk hole of the screw plug (8), and the other end is pressed against the upper spring seat (2).

7. The injector with integrated flow limiting function according to claim 5, characterized in that, The lift h of the valve core (5) is less than the length of the guide part (505) and less than the length of the fourth central hole (407); The flow area of ​​the spiral groove (504) is smaller than the flow area of ​​the oil groove (503); The diameter of the guide part (505) is the same as the diameter of the fourth central hole (407). The guide part (505) and the fourth central hole (407) are fitted with a clearance, so that the valve core (5) can slide freely in the lower spring seat (4).

8. The injector with integrated flow limiting function according to claim 2, characterized in that, The fourth hole (407) has a stress-reducing groove (406) on its hole wall, and the stress-reducing groove (406) is located in connection with the first pressing surface (405).

9. The injector with integrated flow limiting function according to claim 3, characterized in that, One end of the flow-limiting spring (6) is fixed to the bottom surface of the sixth hole (113), and the other end passes through the fifth hole (112) and the fourth hole (109) and is fixed in the spring hole (508) provided on the valve core (5).

10. The injector with integrated flow limiting function according to claim 3, characterized in that, The pressure sleeve (7) includes a mating part (706), which is clearance-fitted with the second hole (104).

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