Oil sprayer integrated with flow limiting function

Abstract

The invention relates to an oil sprayer integrated with a flow limiting function. The oil sprayer comprises a screw plug, an oil sprayer body, an upper spring seat, a fixed spring, a valve element, a pressing sleeve, a lower spring seat and a flow limiting spring. The oil sprayer body is provided with an oil inlet channel, an oil outlet channel, a threaded hole, a first hole, a first sealing conical surface, a second oblique angle, a second hole, a third hole, a fourth hole, a fifth hole and a sixth hole, and the second hole, the third hole, the fourth hole, the fifth hole and the sixth hole form a pressure storage cavity. And the oil inlet channel and the oil outlet channel are respectively communicated with the pressure storage cavity. A flow-limiting spring, a valve core and a lower spring seat are sequentially mounted at the bottom of the pressure storage cavity; the lower spring seat is provided with a first pressing surface, a fourth middle hole, a mounting bevel angle and a first middle hole, and the valve element penetrates through the fourth middle hole and then is pressed on the first pressing surface; a mounting bevel angle of the lower spring seat is pressed on a second bevel angle of the oil sprayer body through a fixing spring; one end of the fixed spring is fixed in the first middle hole, and the other end is fixed on the upper spring seat; and a pressing sleeve and a screw plug are sequentially fixed on the upper spring seat.

Description

Technical Field

[0001] The invention relates to the technical field of a diesel engine high pressure common rail fuel system, in particular to a fuel injector with an integrated flow limiting function. Background Art

[0002] The flow limiting valve is often used in the common rail system. On the one hand, it is used to reduce rail pressure fluctuations. On the other hand, it is used to enable the injector to stop spraying automatically when the injector is overfilled, thereby reducing pollutants and minimizing damage to the machine.

[0003] The common flow limiting valve performs linear reciprocating motion during the movement process, but since it cannot self-rotate, the flow limiting valve cannot be adapted to the single-side oil inlet hole design. Summary of the invention

[0004] The present invention provides a fuel injector with integrated flow limiting function, which is used to enable the fuel injector to realize the integration of flow limiting function and is adapted to the fuel injector with single-side oil inlet hole design.

[0005] The technical solution of this application is: The present application provides an injector with integrated flow limiting function, comprising: an injector body, and a compression sleeve, an upper spring seat, a fixed spring, a lower spring seat, a valve core and a flow limiting spring installed in a pressure storage chamber of the injector body; The injector body also includes an oil inlet passage and an oil outlet passage communicating with the pressure accumulator chamber; The compression sleeve is fixed in the pressure storage chamber; The upper spring seat, the fixed spring and the lower spring seat are sequentially assembled below the compression sleeve; One end of the valve core movably extends into the interior of the lower spring seat from below the lower spring seat; The current limiting spring is arranged between the valve core and the bottom of the pressure accumulator chamber; the valve core is provided with a spiral groove in the circumference; When the injector is turned on to spray fuel and the injection amount does not exceed the set amount, the fuel enters the lower spring seat through the fuel inlet passage and the pressure accumulator chamber, and the valve core moves toward the direction of the flow limiting spring under the action of the downward hydraulic pressure, and the fuel entering the lower spring seat flows downward into the fuel outlet passage through the spiral groove; When the fuel injector does not spray fuel, the valve core is in close contact with the lower spring seat under the upward force of the current limiting spring; When the fuel injection amount of the fuel injector exceeds a set amount, a seal is formed between the valve core and the cavity wall of the pressure accumulation cavity, thereby blocking the fuel entering the lower spring seat from flowing out through the oil outlet passage.

[0006] Preferably, the lower spring seat is provided with a first middle hole, a second middle hole, a third middle hole and a fourth middle hole in sequence; The lower spring seat is also provided with an oil inlet hole connecting the pressure storage chamber and the second middle hole; The diameter of the third hole is smaller than that of the fourth hole, so that a first pressing surface for the valve core to be pressed is formed on one side of the fourth hole close to the third hole; When the injector is not spraying oil, one end of the valve core passes through the fourth center hole and the third center hole and extends into the second center hole, and the valve core is tightly attached to the first pressing surface of the fourth center hole under the upward force of the current limiting spring.

[0007] Preferably, the pressure accumulator chamber includes a second hole, a third hole, a fourth hole, a fifth hole and a sixth hole arranged from top to bottom; 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; The oil inlet passage is connected to the third hole, the fourth hole is connected to the fifth hole via 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; The lower spring seat is arranged in the third hole, and the installation bevel of the lower spring seat is pressed against the second bevel.

[0008] Preferably, a ring-shaped sunken groove is provided on the side of the lower spring seat, the inlet of the oil inlet hole is arranged in the sunken groove, and the hole walls of the sunken groove and the third hole are opposite to each other, so that the fuel entering through the oil inlet passage enters the sunken groove and then enters the second middle hole through the oil inlet hole connected with the sunken groove; The sink groove is arranged 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.

[0009] Preferably, the valve core comprises: a guide portion and a balancing shaft connected to each other, wherein the outer diameter of the guide portion is larger than the outer diameter of the balancing shaft; An oil groove is arranged on the second pressing surface where the guide part is connected to the balance shaft, and the spiral groove communicating with the oil groove is arranged on the outer periphery of the guide part; A third sealing cone surface is formed on one side of the guide portion facing the current limiting spring; The outer diameter of the balancing shaft is smaller than the diameter of the third central hole, and when the valve core moves to make the second pressing surface and the first pressing surface close to each other, the spiral groove is connected with the third central hole through the oil groove; When the fuel injection amount of the fuel injector exceeds a set amount, a seal is formed between the third sealing cone surface and the second sealing cone surface to block the fuel entering the lower spring seat from flowing out through the oil outlet passage.

[0010] Preferably, the injector body further includes a first hole communicating with the second hole, and a threaded hole communicating with the first hole; The first hole and the second hole are connected via a first sealing cone surface; The fuel injector further comprises: a screw plug; The head of the screw plug passes through the threaded hole and the first hole to form a fit with the first sealing cone surface, and the screw plug is threadedly connected to the threaded hole; One end of the compression sleeve is fixed in the countersunk hole of the screw plug, and the other end is pressed tightly on the upper spring seat.

[0011] 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 middle hole; The flow area of ​​the spiral groove is smaller than the flow area of ​​the oil groove; The diameter of the guide portion is the same as the diameter of the fourth center hole, and the guide portion and the fourth center hole are clearance-matched so that the valve core can slide freely in the lower spring seat.

[0012] Preferably, a stress reducing groove is arranged on the hole wall of the fourth central hole, and the stress reducing groove is arranged to be connected with the first pressing surface.

[0013] Preferably, one end of the current limiting spring is fixed to the bottom surface of the sixth hole, and the other end is fixed in a spring hole provided on the valve core after passing through the fifth hole and the fourth hole.

[0014] Preferably, the press sleeve comprises a fitting portion, and the fitting portion is clearance-fitted with the second hole.

[0015] The beneficial effects of this application are: By designing a pressure accumulator chamber inside the injector body, the injector body acts as a common rail pipe, simplifying the parts; in addition, the relevant components that realize the function of the flow limiting valve are installed in the pressure accumulator chamber, saving the external space of the flow limiting valve; the relevant components that realize the function of the flow limiting valve are arranged close to the injection end, which can more effectively reduce the pressure fluctuation; when the injector is working, the spiral groove design can make the valve core produce self-rotation while moving in a straight line, which can better adapt to the single-sided oil inlet hole design and ensure reliability; the fuel is filled in the spiral groove, so that the valve core also has the function of self-lubrication, which reduces the risk of sticking during movement and responds faster. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the structure of a fuel injector with integrated current limiting function according to an embodiment of the present invention; Figure 2 The second structural schematic diagram of the fuel injector with integrated current limiting function according to an embodiment of the present invention; Figure 3 It is a structural schematic diagram of a fuel injector body according to an embodiment of the present invention; Figure 4 It is a structural schematic diagram of a lower spring seat according to an embodiment of the present invention; Figure 5A schematic diagram of the structure of a valve core according to an embodiment of the present invention; Figure 6 A schematic diagram of the structure of a valve core according to an embodiment of the present invention; Figure 7 It is a structural schematic diagram of a compression sleeve according to an embodiment of the present invention; Figure 8 It is a structural schematic diagram of a compression sleeve according to an embodiment of the present invention; Description of reference numerals: 1—injector body; 101—threaded hole; 102—first hole; 103—first sealing cone surface; 104—second hole; 105—first bevel; 106—third hole; 107—second bevel; 108—oil inlet passage; 109—fourth hole; 110—second sealing cone surface; 111—oil outlet passage; 112—fifth hole; 113—sixth hole; 2—upper spring seat; 3—fixed spring; 4—lower spring seat; 401—first center hole; 402—second center hole; 403—oil inlet hole; 404—third center hole; 405—first pressing surface; 406—stress reducing groove; 407—fourth center hole; 408—first outer circle; 409—sunk groove; 410—second outer circle; 411—third outer circle; 412—installation bevel; 5—valve core; 501 - balance shaft; 502 - second pressing surface; 503 - oil groove; 504 - spiral groove; 505 - guide portion; 506 - positioning circle; 507 - third sealing cone surface; 508 - spring hole; 6—current limiting spring; 7—pressing sleeve; 701—first balancing hole; 702—second balancing hole; 703—third balancing hole; 704—through hole; 706—matching portion; 8—screw plug. DETAILED DESCRIPTION

[0017] like Figure 1 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, a fuel injector with integrated flow limiting function comprises a fuel injector body 1, a lower spring seat 4, a valve core 5, a flow limiting spring 6, a compression sleeve 7 and a screw plug 8.

[0018] Reference Figure 3 A pressure storage chamber and an oil inlet passage 108 and an oil outlet passage 111 connected to the pressure storage chamber are arranged in the injector body 1.

[0019] Specifically, holes are opened on the upper surface of the injector body 1 to form 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 above-mentioned pressure storage chamber.

[0020] Reference Figure 3 The first hole 102 and the second hole 104 are connected by a first sealing cone surface 103, the second hole 104 and the third hole 106 are connected by a first bevel 105, the third hole 106 and the fourth hole 109 are connected by a second bevel 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 a second sealing cone surface 110, the fifth hole 112 is connected to the oil outlet passage 111, and the fifth hole 112 is connected to the sixth hole 113.

[0021] 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 bevel 107 .

[0022] Reference Figure 4 The upper surface of the lower spring seat 4 is opened to form a first middle hole 401, a second middle hole 402, a third middle hole 404 and a fourth middle hole 407 from top to bottom.

[0023] Reference Figure 2 and 4 An oil inlet hole 403 is provided on the side of the lower spring seat 4, and the oil inlet hole 403 is connected to the second middle hole 402. An annular recessed 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 recessed groove 409. The recessed groove 409 and the hole wall of the third hole 106 are opposite to each other, so that the fuel entering through the oil inlet passage 108 enters the recessed groove 409, and then enters the second middle hole 402 through the oil inlet hole 403 connected to the recessed groove 409.

[0024] Combination Figure 2 The fuel entering the second center hole 402 passes upward through the first center hole 401 into the second hole 104 above the lower spring seat 4, and passes downward through the third center hole 404 into the fourth center hole 407.

[0025] Reference Figure 4 The sink groove 409 is disposed 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.

[0026] Reference Figure 2 and Figure 4The diameter of the third center hole 404 is smaller than that of the fourth center hole 407 , so that the fourth center hole 407 forms a first pressing surface 405 for the valve core 5 to be pressed on the side close to the third center hole 404 .

[0027] Reference Figure 4 A stress reducing groove 406 is further provided on the hole wall of the fourth middle hole 407 on the lower spring seat 4, and the stress reducing groove 406 is arranged 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.

[0028] Reference Figure 2 One end of the valve core 5 passes through the fourth center hole 407 and the third center hole 404 of the lower spring seat 4 and then extends into the second center hole 402.

[0029] Reference Figure 5 and Figure 6 The valve core 5 includes: a connected guide part 505 and a balancing shaft 501, the outer diameter of the guide part 505 is larger than the outer diameter of the balancing shaft 501; an oil groove 503 is provided on the second clamping surface 502 where the guide part 505 is connected to the balancing shaft 501, a spiral groove 504 is provided on the outer periphery of the guide part 505, a spring hole 508 is opened on the end surface of the guide part 505 on the side facing the current limiting spring 6, a positioning outer circle 506 is formed on the side of the guide part 505 facing the current limiting spring 6, and a third sealing cone surface 507 is formed between the end surfaces of the positioning outer circle 506 on the side facing the current limiting spring 6.

[0030] The fuel in the spiral groove 504 applies a lateral force to the valve core 5, so that the valve core 5 performs a rotational motion around its own center while performing a linear reciprocating motion.

[0031] Reference Figure 5 and Figure 6 The outer diameter of the balance shaft 501 is smaller than the aperture of the third center hole 404. When the valve core 5 moves to a state where the second pressing surface 502 and the first pressing surface 405 are in contact with each other, the spiral groove 504 is connected to the third center 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.

[0032] Reference Figure 2 and Figure 3 One end of the current 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 .

[0033] Reference Figure 1 and Figure 3 The head of the screw plug 8 passes through the threaded hole 101 and the first hole 102 and fits with the first sealing cone surface 103 , and the screw plug 8 is threadedly connected to the threaded hole 101 .

[0034] Reference Figure 1 , Figure 7 and Figure 8 The pressing sleeve 7 is in the second hole 104 of the pressure storage chamber, one end of the pressing sleeve passes through the rear end and is fixed in the countersunk hole of the screw plug 8, and the other end is pressed tightly on the upper spring seat 2.

[0035] Reference Figure 2 The upper spring seat 2 is in the second hole 104 of the pressure storage chamber and is pressed against the pressing sleeve 7 by the fixing spring 3.

[0036] Reference Figure 2 The fixed spring 3 is in the second hole 104 of the pressure storage chamber, one end of which is connected to the bottom of the first middle hole 401 of the lower spring seat 4, and the other end of which is fixedly connected to the upper spring seat 2.

[0037] like Figure 2 and Figure 3 As shown, the full angle of the first bevel 105 is designed to be less than 20°, which is convenient for installing the lower spring seat 4 and can guide the lower spring seat 4, making the installation smoother.

[0038] like Figure 2 , Figure 6 and Figure 7 As shown, the pressing sleeve 7 includes a matching portion 706, and the matching portion 706 is loosely matched with the second hole 104. When the pressing sleeve 7 is pressed against the upper spring seat 2, the matching portion 706 matches with the second hole 104 to ensure that the error between the center of the pressing sleeve 7 and the center of the second hole 104 is as small as possible, and the force applied to the spring seat 2 is balanced without generating lateral force. Furthermore, the lower spring seat 4 can be better fixed.

[0039] In the initial state (i.e., when the injector has not started to spray fuel), no fuel has yet entered from the fuel inlet passage 108. For the lower spring seat 4, it is only subjected to the downward force exerted by the fixing spring 3, so that the installation angle 412 of the lower spring seat 4 is pressed against the second angle 107 of the injector body 1; for the valve core 5, due to the upward force exerted 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.

[0040] When the injector starts to spray fuel but the injection amount does not exceed the set injection amount, the fuel enters the gap between the hole wall of the third hole 106 and the groove 409 from the oil inlet channel 108. 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 groove 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.

[0041] The fuel entering the sink 409 will further pass through the oil inlet hole 403 of the lower spring seat 4 and enter the second middle hole 402 of the lower spring seat 4, and then the fuel will flow into the following two oil paths: one is that the fuel in the second middle hole 402 passes through the first middle hole 401, the second hole 104, and the middle hole of the upper spring seat 2 to enter the through hole 704 of the pressing sleeve 7, and then passes through the first balancing hole 701, the second balancing hole 702, and the third balancing hole 703 of the pressing sleeve 7 to finally reach the first cavity formed between the matching portion 706 of the pressing sleeve 7 and the hole wall of the second hole 104; the other is that the fuel in the first middle hole 402 passes through the third middle hole 404, the fourth middle hole 407, the oil groove 503, and the spiral groove 504 to flow into the fourth hole 109, the fifth hole 112 and the sixth hole 113, and finally enters other components of the injector through the oil outlet 111 connected to the fifth hole 112. At this time, the downward force applied to the lower spring seat 4 includes not only the downward force applied by the fixed spring 3, but also the downward hydraulic pressure applied by the fuel in the third hole 106; the upward force applied to the lower spring seat 4 comes from the upward hydraulic pressure applied by the fuel in the fourth hole 109. Since the diameter of the third hole 106 is designed to be larger than the diameter of the fourth hole 109, the downward hydraulic pressure applied to the lower spring seat 4 is larger than the upward hydraulic pressure, so that the installation bevel 412 of the lower spring seat 4 can be well pressed against the second bevel 107 of the injector body 1.

[0042] like Figure 4 As shown, the oil inlet hole 403 of the lower spring seat 4 is composed of four holes of equal diameter, and the four oil inlet holes 403 are evenly distributed on the cylindrical surface of the second middle 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 fixation of the lower spring seat 4 by the lateral force. Based on a similar principle, the oil groove 503 of the valve core 5 is also designed as two symmetrically distributed square grooves, and the first balance hole 701, the second balance hole 702, and the third balance hole 703 on the press sleeve 7 are all designed to be centrally symmetrically distributed, thereby reducing the influence of fuel on the lateral force of the parts.

[0043] like Figure 1 As shown, in the embodiment of the present application, the working process of the injector mainly includes three stages: The first stage is the initial state, at which the injector does not spray oil. Due to the spring force applied by the current limiting spring 6 to the valve core 5, the first pressing surface 405 of the lower spring seat 4 is tightly fitted with the second pressing surface 502 of the valve core 5; and at this time, the lift h of the valve core 5 is 0.

[0044] The second stage is when the injector starts to spray oil and the amount of oil sprayed does not exceed the set amount of oil sprayed, the valve core 5 moves toward the direction of the flow limiting spring 6 under the action of the downward hydraulic pressure, and at this time, the h of the valve core 5 is between 0 and the set value; when the injector does not spray oil, 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 moment when the lift h of the valve core 5 is 0, the first pressing surface 405 of the lower spring seat 4 hits the second pressing surface 502, and at this time, the stress reduction groove 406 set on the lower spring seat 4 can make the second pressing surface 502 and the first pressing surface 405 fit tightly together, and can reduce the stress caused by the collision between the first pressing surface 405 and the second pressing surface 502; during this process, the valve core 5 performs linear reciprocating motion.

[0045] The third stage is when the injection amount of the injector exceeds the set injection amount, the valve core 5 moves toward the direction of the flow limiting spring 6 under the action of the downward hydraulic pressure until the third sealing cone surface 507 of the valve core 5 is pressed against the second sealing cone surface 110 of the injector body 1. Figure 2 As shown, at this time, the oil circuit of the pressure accumulator chamber is blocked, there is no fuel in the oil outlet passage 111, and the injector does not spray fuel.

[0046] In the embodiment of the present application, during the movement of the valve core 5, since the spiral groove 504 is provided on the guide portion 505 of the valve core 5, the fuel in the spiral groove 504 will apply lateral force to the valve core 5, so that the valve core 5 can rotate around its own center while performing linear reciprocating motion.

[0047] In the embodiment of the present application, the oil outlet 111 is arranged on the side of the injector body. When the injection amount exceeds the set injection amount, the third sealing cone surface 507 of the valve core 5 is pressed against the second sealing cone surface 110. Due to the laterally distributed oil outlet 111, the third sealing cone surface 507 of the valve core 5 is subjected to uneven force, resulting in uneven force against the second sealing cone surface 110. If the valve core 5 itself does not rotate, the point where the valve core 5 hits the second sealing cone surface 110 is the same each time. This situation is prone to fatigue of a certain point and reduces the service life. In the embodiment of the present application, since the valve core 5 can rotate itself while performing linear motion, the point where the third sealing cone surface 507 hits the second sealing cone surface 110 is different each time, thereby reducing fatigue points and increasing service life. Figure 1 , Figure 5 and Figure 6 The diameter of the guide portion 505 is the same as the diameter of the fourth center hole 407 of the lower spring seat 4 , and the guide portion 505 and the fourth center hole 407 are clearance-matched so that the valve core 5 can slide freely in the lower spring seat 4 .

[0048] In addition, since the flow area of ​​the spiral groove 504 provided on the valve core 5 is smaller than the flow area of ​​the oil groove 503, the spiral groove 504 has the function of a throttling hole. When the injection amount exceeds the set injection amount, due to the existence of the spiral groove 504, the fuel in the second cavity passes through the spiral groove 504 and reaches the fourth hole 109. Since the flow area of ​​the spiral groove 504 can meet the normal injection requirements, the valve core 5 will move toward the flow limiting spring 6 to compensate for the reduced injection amount. After the injection amount exceeds the set injection amount, the fuel passing through the spiral groove 504 is not enough to supplement the reduced injection amount. At this time, the valve core 5 compensates for the fuel by moving toward the flow limiting spring 6 until the valve core 5 is closed. In addition, in addition to the functions of oil passage and throttling hole, the spiral groove 504 can also play a lubricating role, so that the valve core 5 can run smoothly in the lower spring seat 4. Since the lift h of the valve core 5 is less than the length of the guide portion 505 and less than the length of the fourth center hole 407, even if the lift h of the valve core 5 is at the set maximum value, the guide portion 505 of the valve core 5 is still in the fourth center hole 407 of the lower spring seat 4, so that the valve core 5 can be guided when returning to its position and is not prone to jamming.

Claims

1. A fuel injector with integrated current limiting function, characterized in that: include: A fuel injector body (1), and a compression sleeve (7), an upper spring seat (2), a fixed spring (3), a lower spring seat (4), a valve core (5), and a flow limiting spring (6) installed in a pressure storage chamber of the fuel injector body (1); The injector body (1) further comprises an oil inlet passage (108) and an oil outlet passage (111) which are in communication with the pressure accumulator chamber; The pressing sleeve (7) is fixed in the pressure storage chamber; The upper spring seat (2), the fixed spring (3) and the lower spring seat (4) are sequentially assembled below the compression sleeve; One end of the valve core (5) movably extends from below the lower spring seat (4) into the interior of the lower spring seat (4); The flow limiting spring (6) is arranged between the valve core (5) and the bottom of the pressure storage chamber; the valve core (5) is provided with a spiral groove (504) in the circumferential direction; When the fuel injector starts to spray fuel and the fuel injection amount does not exceed the set amount, the fuel enters the lower spring seat (4) through the fuel inlet passage (108) and the pressure accumulator chamber, and the valve core (5) moves in the direction of the flow limiting spring (6) under the action of the downward hydraulic pressure, and the fuel entering the lower spring seat (4) flows downward into the fuel outlet passage (111) through the spiral groove (504); When the fuel injector is not spraying fuel, the valve core (5) is in close contact with the lower spring seat (4) under the upward force of the flow limiting spring (6); When the fuel injection amount of the fuel injector exceeds a set amount, a seal is formed between the valve core (5) and the cavity wall of the pressure accumulation cavity, thereby blocking the fuel entering the lower spring seat (4) from flowing out through the oil outlet passage (111).

2. The fuel injector with integrated current limiting function according to claim 1, characterized in that: The lower spring seat (4) is provided with a first middle hole (401), a second middle hole (402), a third middle hole (404) and a fourth middle hole (407) in sequence; The lower spring seat (4) is also provided with an oil inlet hole (403) for connecting the pressure storage 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 a first pressing surface (405) for pressing the valve core (5) is formed on one side of the fourth central hole (407) close to the third central hole (404); When the fuel injector is not spraying fuel, one end of the valve core (5) passes through the fourth center hole (407) and the third center hole (404) and extends into the second center hole (402), and the valve core (5) is in close contact with the first pressing surface (405) of the fourth center hole (407) under the upward force of the flow limiting spring (6).

3. The fuel injector with integrated current limiting function according to claim 1, characterized in that: The pressure storage chamber comprises 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 via a first bevel (105), and the third hole (106) and the fourth hole (109) are connected via a second bevel (107); The oil inlet passage (108) is in communication with the third hole (106), the fourth hole (109) is connected with the fifth hole (112) via a second sealing cone surface (110), the fifth hole (112) is in communication with the oil outlet passage (111), and the fifth hole (112) is in communication with the sixth hole (113); The lower spring seat (4) is arranged in the third hole (106), and the installation bevel (412) of the lower spring seat (4) is pressed against the second bevel (107).

4. The fuel injector with integrated current limiting function according to claim 3, characterized in that: The side surface of the lower spring seat (4) is provided with an annular recessed groove (409), the inlet of the oil inlet hole (403) is arranged in the recessed groove (409), and the hole walls of the recessed 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 recessed groove (409) and then enters the second middle hole (402) through the oil inlet hole (403) connected to the recessed groove (409); The sink groove (409) is arranged between a first outer circle (408) and a second outer circle (410) of the lower spring seat (4); the first outer circle (408) and the second outer circle (410) have the same outer diameter.

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

6. The fuel injector with integrated current limiting function according to claim 1, characterized in that: The fuel injector body further comprises 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 via a first sealing cone surface (103); The fuel injector further comprises: a screw plug (8); The head of the screw plug (8) passes through the threaded hole (101) and the first hole (102) to form a fit with the first sealing cone surface (103), and the screw plug (8) is threadedly connected to the threaded hole (101); One end of the compression 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 fuel injector with integrated current 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 portion (505) and less than the length of the fourth center 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 portion (505) is the same as the diameter of the fourth center hole (407), and the guide portion (505) and the fourth center hole (407) are clearance-matched, so that the valve core (5) can slide freely in the lower spring seat (4).

8. The fuel injector with integrated current limiting function according to claim 2, characterized in that: A stress reducing groove (406) is provided on the hole wall of the fourth central hole (407), and the stress reducing groove (406) is arranged to be connected to the first pressing surface (405).

9. The fuel injector with integrated current limiting function according to claim 3, characterized in that: One end of the current 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 a spring hole (508) provided on the valve core (5).

10. The fuel injector with integrated current limiting function according to claim 1, characterized in that: The pressing sleeve (7) comprises a matching portion (706), and the matching portion (706) is clearance-matched with the second hole (104).

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