CN106545448B

CN106545448B - Double-path oil inlet resonance bypass type electric control oil injector

Info

Publication number: CN106545448B
Application number: CN201710034964.1A
Authority: CN
Inventors: 刘秀琴; 范立云
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2017-01-18
Filing date: 2017-01-18
Publication date: 2022-07-15
Anticipated expiration: 2037-01-18
Also published as: CN106545448A

Abstract

The invention aims to provide a double-path oil inlet resonance bypass type electric control oil injector which comprises an oil injector head, an oil injector body, a flow limiting valve component, an electromagnetic valve component, a needle valve component and a nozzle. The flow-limiting valve component is positioned in the pressure accumulation cavity, so that the stability of the oil injection process of each cylinder is ensured under the condition of large oil injection quantity. The bottom of the flow limiting valve assembly is provided with a resonance through hole and a resonance throttling hole, and the fluctuation of fuel oil passing through the flow limiting valve assembly is reduced by utilizing the wave superposition principle. The lower part is provided with a solenoid valve component and a needle valve component. The electromagnetic valve adopts a two-position three-way valve form to reduce the dynamic oil return amount. The control cavity is internally provided with a control slide block which is contacted with the middle block, and the functions of slowing down the oil injection speed in the initial stage of injection and accelerating the seating response of the needle valve are achieved. The control cavity further accelerates the pressure building speed by adopting a double-path oil inlet mode, and the quick response characteristic of the oil sprayer is realized. The inside of the oil sprayer has no static pressure difference, and the oil sprayer has no static leakage.

Description

Double-path oil inlet resonance bypass type electric control oil injector

Technical Field

The invention relates to an engine fuel injection device.

Background

The high-speed electromagnetic valve type oil sprayer realizes a complex oil spraying rule by means of a controller and has the advantages of fast response, high control precision, flexible control strategy and reliable working performance. However, with the gradual increase of the fuel injection pressure in the current fuel injector, the performance of the fuel injector is also tested in various aspects: the static leakage condition of the oil injector exists under the condition of not injecting oil; the dynamic oil return amount of the two-position two-way valve is large, so that the fuel utilization rate is influenced; in the initial stage of injection, the discharge amount of nitrogen oxides is increased due to overlarge oil injection speed, and after the injection is finished, the control cavity is fed with oil in a single way, so that the pressure building speed is slow, the oil is not quickly cut off, and the particulate matter discharge is increased; the movement of the needle valve and the fuel injection can excite water hammer pressure waves to cause the fuel pressure change of each volume cavity; during large-oil-quantity injection, the oil injection process of the oil injector may affect the fluctuation of the common rail pressure, so that the stability and the uniformity of the oil injection process of each cylinder are reduced.

Disclosure of Invention

The invention aims to provide a double-path oil inlet resonance bypass type electronic control oil injector which has the advantages of quick response characteristic, small fuel pressure fluctuation, capability of realizing a slow-to-fast oil injection speed time history curve and no static leakage function.

The purpose of the invention is realized by the following steps:

the invention discloses a double-path oil inlet resonance bypass type electric control oil injector, which is characterized in that: the oil injection device comprises an oil injector head, an oil injector body, a flow limiting valve component, a solenoid valve component, a needle valve component, a nozzle and a downlink high-pressure oil way, wherein the oil injector head is arranged above the oil injector body;

the flow limiting valve assembly comprises a limiting spring seat, a flow limiting piston, a ball valve reset spring seat and a supporting control slider, wherein the limiting spring seat, the flow limiting piston and the ball valve reset spring seat are arranged from top to bottom, a damping spring is arranged between the limiting spring seat and the flow limiting piston, the supporting control slider is arranged in the ball valve reset spring seat, a ball valve is arranged between the upper end of the supporting control slider and the flow limiting piston, a ball valve reset spring is arranged between the lower end of the supporting control slider and the ball valve reset spring seat below the supporting control slider, a piston blind hole and a flow limiting hole are formed in the flow limiting piston, an axial central through hole is formed in the supporting control slider, a resonance through hole and a resonance orifice are formed in the ball valve reset spring seat, a transition oil cavity is formed between the ball valve reset spring seat and an oil sprayer body below the ball valve reset spring seat, the piston blind hole is communicated with a pressure storage cavity and the flow limiting hole, and the flow limiting hole are communicated or disconnected with the axial central through hole under the control of the ball valve, the resonance through hole and the resonance throttling hole are communicated with the axial central through hole and the transition oil cavity;

The electromagnetic valve component comprises an electromagnet, a coil, an armature, a balance valve rod and a valve seat, the balance valve comprises an intermediate block, a coil is wound on the electromagnet, a solenoid valve reset spring seat is arranged above the electromagnet, an armature is arranged below the electromagnet, a solenoid valve reset spring is arranged between the armature and the solenoid valve reset spring seat, a balance valve rod is positioned in a valve seat, the upper end part of the balance valve rod is fixedly connected with the armature, the intermediate block is arranged below the valve seat, a balance valve rod upper cavity is formed between the middle part of the balance valve rod and the valve seat, a balance valve rod lower cavity is formed between the lower end part of the balance valve rod, the valve seat and the intermediate block, an ascending oil inlet hole is arranged in the valve seat, an oil return hole, an intermediate oil duct and an intermediate orifice are arranged in the intermediate block, the ascending oil hole is communicated with the balance valve rod upper cavity, the intermediate orifice is communicated with the balance valve rod lower cavity respectively, and the oil return hole is communicated with or disconnected with the intermediate orifice and the oil tank under the control of the balance valve rod;

the needle valve assembly comprises a needle valve limiting sleeve, a control slider and a needle valve body, wherein the control slider is positioned in the needle valve limiting sleeve, the upper part of the needle valve body is positioned in the needle valve limiting sleeve, the lower part of the needle valve body is positioned in a nozzle, a control cavity is formed between the control slider and the needle valve body, a control slider reset spring is arranged in the control cavity, a bulge part is arranged in the middle of the needle valve body, the needle valve reset spring is arranged between the bulge part and the needle valve limiting sleeve above the bulge part, a middle cavity is arranged on the upper end face of the control slider, an oil inlet hole, a control slider through hole and a bypass oil path are arranged in the control slider, the oil inlet hole is communicated with the middle cavity through an oil inlet throttling hole, the control slider through hole is respectively communicated with the middle cavity and the control cavity, the bypass oil path is communicated with the control cavity, an oil containing groove is formed between the needle valve body and the nozzle, and the end part of the nozzle is provided with a spraying hole;

The middle oil duct is communicated with the middle cavity, the upper end of the downlink high-pressure oil path is communicated with the transition oil cavity, the transition oil cavity is communicated with the oil containing groove through the oil injector body, the valve seat, the middle block, the needle valve limiting sleeve and the nozzle, and the uplink oil inlet hole is communicated with the downlink high-pressure oil path.

The present invention may further comprise:

1. when the spray hole sprays oil, the fuel pressure of the transition oil cavity is reduced, the current-limiting piston, the ball valve and the supporting slide block integrally move downwards, the ball valve is not seated on the ball valve reset spring seat, and the current-limiting hole is communicated with the axial central through hole; when the quality of fuel flowing out of the spray hole exceeds a threshold value, the flow-limiting piston compresses the ball valve and enables the ball valve to be seated on a ball valve reset spring seat, and the flow-limiting hole is disconnected with the axial central through hole; when the spray hole stops spraying oil, the flow-limiting piston, the ball valve and the supporting slide block are integrally restored to the initial positions under the action of the ball valve return spring.

2. When the coil is electrified, the balance valve rod moves upwards, the upper cavity of the balance valve rod and the lower cavity of the balance valve rod are in a disconnected state, the oil return hole and the oil tank are in a communicated state, fuel oil in the control cavity returns to the oil tank through the middle oil duct, the middle throttle hole and the oil return hole, the needle valve body is lifted upwards, and the spray hole opens for oil injection; after the coil is powered off, the balance valve rod moves downwards under the action of the electromagnetic valve reset spring and is pressed on the upper end face of the middle block, the upper balance valve rod cavity is communicated with the lower balance valve rod cavity, the oil return hole is disconnected with the oil tank, and meanwhile, fuel oil in the downlink high-pressure oil way enters the control cavity through the uplink oil inlet hole, the upper balance valve rod cavity, the lower balance valve rod cavity and the middle oil duct on one hand and enters the control cavity through the oil inlet hole and the oil inlet throttling hole on the other hand.

3. When the spray hole stops spraying oil, the fuel pressure of the upper end face of the control slide block is higher than that of the lower end face of the control slide block, the control slide block overcomes the pre-tightening force of the return spring of the control slide block to move downwards, the bypass oil way is opened, and the control slide block returns to the initial position under the action force of the return spring of the control slide block along with the fuel entering the control cavity.

4. The diameter of the middle part of the resonance throttling hole is smaller than the diameters of the two ends of the resonance throttling hole and smaller than the diameter of the resonance through hole, and the total axial length of the resonance throttling hole and the resonance through hole is consistent.

The invention has the advantages that: the invention adopts the pressure accumulation cavity structure, and ensures that the continuous oil injection process of the oil injector can not cause great fluctuation to the common rail fuel pressure to influence the oil injection processes of other oil injectors under the condition of large oil injection quantity. The invention adopts the flow limiting valve assembly, thereby effectively reducing the occurrence of abnormal oil injection conditions and ensuring the normal and stable oil injection process. Meanwhile, a resonance structure is added in the flow limiting valve assembly, so that fuel pressure fluctuation is reduced, and the stability of the fuel injection process is improved. The oil injector adopts the electromagnetic valve to control the balance valve rod to adjust the switch of the oil return circuit, thereby improving the control precision and flexibility, effectively improving the emission of the whole diesel engine and improving the fuel economy. A balance valve rod of the oil sprayer adopts a two-position three-way mode, two-way sealing of a conical surface and a plane can be achieved, and dynamic oil return amount is reduced. The double-circuit oil inlet oil duct, the balanced valve control valve rod of disk seat and the interior processing of centre piece and the bypass oil duct of control intracavity control slider can make the control chamber build pressure more fast, have improved needle valve response characteristic. The design of the throttle hole of the control slide block and the middle throttle ensures that the oil sprayer can slowly spray oil at the initial stage, and the formation of nitrogen oxides is reduced. And the static pressure difference does not exist in the nozzle part, so that the function of static leakage-free of the oil sprayer can be realized.

Drawings

FIG. 1 is a schematic view of the structure of the present invention;

FIG. 2 is a schematic view of a constrictor valve assembly;

FIG. 3 is a schematic view of a solenoid valve assembly;

FIG. 4 is a schematic view of a needle valve assembly;

FIG. 5 is a schematic view A-A.

Detailed Description

The invention will now be described in more detail by way of example with reference to the accompanying drawings in which:

with reference to fig. 1-5, the main structure of the two-way oil inlet resonance bypass type electric control oil injector comprises an oil injector head 1, an oil injector body 11, a flow limiting valve assembly 3, an electromagnetic valve assembly 10, a tight cap 9, a needle valve assembly 5 and a nozzle 6. The injector head 1 is connected with the injector body 11 in a matching way through threads and is sealed by a sealing ring 12 arranged on the injector body 11. The main oil inlet hole 13 on the injector head 1 is communicated with the pressure accumulation cavity 2 in the injector body 11. Below the injector body 11, there are a solenoid valve assembly 10, a nozzle 6 and a needle valve assembly 5, which are assembled and connected by a locking cap 9. The flow limiting valve component 3 is arranged in the oil injector body 11 and mainly comprises a retainer ring 14, a limiting spring seat 27, a damping spring 15, a flow limiting piston 16, a ball valve 25, a supporting control slider 18, a ball valve return spring 19 and a ball valve return spring seat 23. The flow-limiting piston 16 is provided with a flow-limiting hole 17 and a piston blind hole 26, and the supporting control slider 18 is provided with an axial central through hole 24 to ensure that fuel oil can pass through a lower oil path. Two resonance holes, namely a resonance throttling hole 22 and a resonance through hole 20, are machined at the bottom of the ball valve reset spring seat 23. An electromagnetic valve assembly 10 is arranged between the bottom of the oil injector body 11 and the upper part of the nozzle 6, and mainly structurally comprises an electromagnetic valve return spring 28, an electromagnetic valve return spring seat 39, a coil 29, an electromagnet 38, an armature 37, a valve seat 30, an intermediate block 34 and a balance valve rod 36. The armature 37 and the balance valve rod 36 are placed in combination in the valve seat 30, and the upper oil inlet hole 31 is machined in the valve seat 30. An oil return hole 32, an intermediate oil passage 33, an intermediate orifice 35, and the like are machined in the intermediate block 34. The needle valve assembly 5 is arranged below the electromagnetic valve assembly 10, and mainly structurally comprises a control slide block 47, a needle valve limiting sleeve 45, a control slide block return spring 42, a needle valve body 43 and a needle valve return spring 44. The control slider 47 is disposed in the control chamber 46, and is machined with an oil inlet orifice 49, a control slider through-hole 41, and a bypass oil passage 40. The oil inlet orifice 49 is communicated with the oil inlet hole 48 on the needle valve limiting sleeve 45.

Fig. 1 is a schematic diagram of the overall structure of a fuel injector according to the present invention. A main oil inlet hole 13 is processed on the injector head 1, and high-pressure fuel oil conveyed by a high-pressure oil pipe enters the inside of the injector through the main oil inlet hole 13. The injector head 1 and the injector body 11 are assembled through threads, and a sealing ring 12 is arranged between the injector head and the injector body for sealing. The main oil inlet hole 13 communicates with the pressure accumulation chamber 2. The fuel in the accumulator chamber 2 will pass down through the constrictor valve assembly 3. After flowing out of the flow limiting valve assembly 3, the fuel enters the control cavity 46 and the oil containing groove 8 through the descending high-pressure oil way 4. A solenoid valve assembly 10 is arranged between the lower part of the oil injector body 11 and the needle valve assembly 5. The lifting and seating of the armature 37 and the balance valve stem 36 is controlled by electromagnetic forces within the solenoid operated valve assembly 10. When the balance valve rod 36 is lifted upward, the oil return hole 32 is opened, and the fuel in the control chamber 46 flows through the control slider through hole 41, the intermediate oil passage 33, and the intermediate orifice 35, and is discharged through the oil return hole 32. The fuel pressure in the control chamber 46 drops and forms a fuel pressure difference with the oil tank 8, so that the needle valve body 43 is lifted and the oil injection starts. At this time, the needle valve body 43 is limited by the needle valve limiting sleeve 45. Due to the two-stage throttling action of the control slider through hole 41 and the intermediate throttling hole 35, the fuel pressure of the intermediate oil passage 33 does not drop rapidly, so that the dropping speed of the fuel pressure of the control chamber 46 is slowed down. When the balance valve rod 36 is seated downwards, the oil return hole 32 is closed, fuel can directly enter the control cavity 46 through the uplink oil inlet hole 31, the balance valve rod 36, the middle throttle hole 35, the middle oil passage 37, the control slider through hole 41 and the bypass oil passage 40, and can also directly enter the control cavity 46 through the oil inlet hole 48 and the oil inlet throttle hole 49, so that the control cavity 46 is pressurized, the needle valve body 43 is seated, and the oil injection process is finished. Meanwhile, a needle valve body 43 pressed by a needle valve return spring 44 is placed in the nozzle 6, and fig. 5 is an enlarged view of a section a-a of the needle valve body 43. The arc-shaped surface of the needle valve body 43 can play a good role in guiding. And static pressure difference does not exist in the needle valve component 5, so that the characteristic of no static leakage of the oil injector is ensured. The needle valve component 5 and the solenoid valve component 10 are placed in the tightening cap 9 and are fastened with the oil injector body 11 through threads.

Fig. 2 is a schematic view of a portion of a constrictor valve assembly of the present invention. The flow limiting valve assembly 3 mainly comprises a retainer ring 14, a limiting spring seat 27, a damping spring 15, a flow limiting piston 16, a ball valve 25, a supporting control slider 18, a ball valve return spring 19, a ball valve return spring seat 23 and the like. The entire restrictor valve assembly 3 is arranged inside the injector body 11 via the pressure accumulation chamber 2 and is restricted by the collar 14. The limit spring seat 27 cooperates with the retainer ring 14 to act, on the one hand, as a spring seat for the damping spring 15 and, on the other hand, to limit the maximum displacement of the restrictor piston 16. Under the spring pre-tightening force of the damping spring 15 and the ball valve return spring 19, the ball valve 25 is matched with the lower end surface of the flow limiting piston 16 and the upper end surface of the supporting control slide block 18. The ball return spring seat 23 is pressed against the bottom by the spring force of the ball return spring 19, and its upper variable cross-section is the seating surface of the ball 25. From the pressure accumulation chamber 2, the fuel enters a blind piston bore 26 in the restrictor piston 16 and then enters the axial central through-hole 24 of the support control slide 18 via the restrictor orifice 17. The fuel flowing out of the axial central through hole 24 passes through the resonance through hole 20 and the resonance orifice 22 into the transition oil chamber 21. The provision of the machined resonant through holes 20 and the resonant orifice 22 results in a reduction in the amplitude of the fuel pressure wave passing through both holes. Because there is one section aperture in resonance orifice 22 to be littleer than resonance through-hole 20, its throttle effect is stronger, causes the fuel velocity of flow that flows through from two holes to be different for the fuel pressure wave of original looks produces the phase difference, and two strands of fuel pressure waves offset each other after the stack, and the pressure fluctuation further reduces, and the total length in the axial of two holes is the same. The descending high-pressure oil path 4 is communicated with the transition oil chamber 21 and leads to the lower oil path. When the oil injector injects oil normally, the jet hole 7 sprays the fuel oil, and the pressure of the fuel oil in the transition oil cavity 21 is reduced. Due to the throttling effect of the throttling hole 17 on fuel, the pressure of the fuel in the piston blind hole 26 in the throttling piston 16 and the pressure accumulation cavity 2 is higher, and pressure difference is formed between the pressure and the transition oil cavity 21, so that the throttling piston 16, the ball valve 25 and the supporting control slide block 18 displace downwards to compensate the fuel sprayed by the fuel injector, but the ball valve 25 cannot be seated on the ball valve reset spring seat 23. When the oil injection is finished, the pressure difference between the upper part and the lower part of the flow-limiting piston 16 is gradually reduced along with the flow of the fuel oil through the flow-limiting hole 17, and the flow-limiting piston 16, the ball valve 25 and the supporting control slide block 18 are restored to the original positions under the action of the return spring force of the ball valve. When the fuel injector continuously injects fuel, the mass of the fuel flowing out exceeds the threshold value, and the fuel injector is in an abnormal working state, because the flow of the fuel injected by the injection hole 7 is large and the flow speed is high, the oil pressure of the transition oil cavity 21 below the flow limiting piston 16 is rapidly reduced, and an up-down pressure difference is formed, so that the flow limiting piston 16 presses the ball valve 25 to be seated on the ball valve reset spring seat 23, and the fuel is prevented from flowing. Due to the lack of fuel supply, the fuel injector stops operating, preventing continuation of abnormal fuel injection.

Fig. 3 is a schematic view of a part of the structure of the solenoid valve assembly of the present invention. The solenoid valve assembly 10 mainly includes a solenoid valve return spring 28, a solenoid valve return spring seat 39, a coil 29, an electromagnet 38, an armature 37, a valve seat 30, an intermediate block 34, a balance valve rod 36, and the like. The solenoid valve return spring seat 39, the solenoid valve return spring 28, the coil 29 and the electromagnet 38 are embedded inside the injector body 11, wherein the solenoid valve return spring seat 39 is fastened to the topmost end of the solenoid valve by a screw thread. Between the solenoid valve return spring seat 39 and the armature 37 is the solenoid valve return spring 28. The armature 37 and the balancing valve rod 36 are placed inside the valve seat 30 below the injector body 11. The component that engages the valve seat 30 at the bottom is an intermediate block 34. The whole electromagnetic valve is in the form of a two-position three-way valve. When the injector starts to inject oil, the coil 29 of the electromagnetic valve is electrified to form a magnetic loop with the electromagnet 38 and the armature 37, so as to generate electromagnetic force, attract the balance valve rod 36 to move upwards, open the oil return hole 32 in the middle block 34 and block the upward oil inlet hole 31. At this time, the fuel in the control chamber 46 returns to the fuel tank through the intermediate oil passage 33, the intermediate orifice 35, and the return hole 32, and the pressure in the control chamber 46 decreases, so that the upper surface of the needle valve body 43 is pressed and reduced, and a pressure difference is formed with the fuel pressure in the oil reservoir 8. The needle valve body 43 is lifted upwards to open the spray hole 7 for spraying oil. When the injector stops injecting fuel, the armature 37 and the balance valve rod 36 are tightly combined into a whole, so that they are pressed on the intermediate block 34 and block the oil return hole 32 under the spring pre-load of the solenoid valve return spring 28. Meanwhile, the balance valve rod 36 opens an oil path from the ascending oil inlet 31, the middle throttling hole 35 and the middle oil passage 33 to the control cavity 46, and simultaneously feeds oil to the oil feeding throttling hole 49 on the control slide block 47, so that the pressure building speed of the normal single oil feeding hole to the control cavity 46 is improved, and the seating speed of the needle valve is accelerated.

FIG. 4 is a schematic view of a portion of a needle valve assembly according to the present invention. The needle valve assembly 5 mainly comprises a control slider 47, a control slider return spring 42, a needle valve stop collar 45, a needle valve body 43 and a needle valve return spring 44. A control slide 47 is placed inside the control chamber 46 and is lifted up against the lower end face of the intermediate block 34 by a control slide return spring 42. An oil inlet hole 48 is processed on the needle valve limiting sleeve 45. An oil inlet throttle hole 49, a control slider through hole 41 and a bypass oil passage 40 are machined in the control slider 47. When the oil injection starts, due to the two-stage throttling action of the middle throttling hole 35 on the middle block 34 and the control slide block through hole 41, the pressure of the fuel oil in the control cavity 46 drops more slowly than that of the normal oil injector, and the effect of reducing the emission of nitrogen oxides is achieved. When the oil injection is finished, because the fuel pressure at the upper end surface of the control slide block 47 is higher than that at the lower end surface, the control slide block 47 can overcome the spring pre-tightening force of the control slide block return spring 42 to displace downwards and open the bypass oil passage 40, so that the fuel pressure in the control cavity 46 is established more quickly, and the seating response of the needle valve is improved. As fuel enters the control chamber 46, the oil pressure on the upper and lower end surfaces of the control slider 47 tends to be consistent. The control slider 47 is reset by the control slider return spring 42.

According to the working process, in the oil injection process of the two-way oil inlet resonance bypass type electric control oil injector, a two-position three-way valve mode is adopted, the two-way oil inlet of the electromagnetic valve balance valve rod 36 and the inner part of the middle block 34 is adopted, the pressure building process of the control cavity 46 is accelerated, and the response speed of the needle valve seating is improved. The resonance structure effectively reduces the fuel pressure fluctuation and improves the stability of the fuel injection process. The structure of the control slide block through hole 41 and the bypass oil passage 40 of the control slide block 47 arranged in the control cavity 46 ensures the characteristics of low oil injection speed in the initial stage of injection and quick oil cut-off after the end of oil injection. The whole oil injection process is controlled by an electromagnetic valve, and the electromagnetic force is utilized to drive the balance valve rod 36 to move, so that the requirements of high response speed, high control precision and variable oil injection rule in the oil injection process are met. The oil sprayer body 11 is internally provided with the flow limiting valve component 3, so that the abnormal oil spraying state is prevented from being continuously carried out, and the stability of the working process is ensured. When the common rail pressure storage cavity is applied to a common rail system, the pressure storage cavity 2 can effectively reduce the pressure fluctuation of the common rail under the large-oil-volume injection state, so that the phenomena of uniformity and stability reduction of the oil injection process of each cylinder are reduced.

Claims

1. Double-circuit oil feed resonance by-pass type electronic control oil sprayer, characterized by: the oil sprayer comprises an oil sprayer head, an oil sprayer body, a flow limiting valve assembly, a solenoid valve assembly, a needle valve assembly, a nozzle and a downlink high-pressure oil way, wherein the oil sprayer head is arranged above the oil sprayer body, a main oil inlet hole is formed in the oil sprayer head, a pressure accumulation cavity is formed in the oil sprayer body, the main oil inlet hole is communicated with the pressure accumulation cavity, the flow limiting valve assembly is arranged in the pressure accumulation cavity, the solenoid valve assembly, the needle valve assembly and the nozzle are sequentially arranged at the lower end of the oil sprayer body, a tightening cap is positioned outside the solenoid valve assembly, the needle valve assembly and the nozzle, and the upper end of the tightening cap is connected with the lower end of the oil sprayer body in a threaded connection mode;

2. The two-way oil inlet resonance bypass type electric control oil injector according to claim 1, characterized in that: when the spray hole sprays oil, the fuel pressure of the transition oil cavity is reduced, the flow-limiting piston, the ball valve and the supporting slide block integrally move downwards, the ball valve is not seated on the ball valve reset spring seat, and the flow-limiting hole is communicated with the axial central through hole; when the mass of the fuel flowing out of the spray hole exceeds a threshold value, the flow limiting piston compresses the ball valve and enables the ball valve to be seated on a ball valve reset spring seat, and the flow limiting hole is disconnected with the axial central through hole; when the spray hole stops spraying oil, the flow-limiting piston, the ball valve and the supporting slide block are integrally restored to the initial positions under the action of the ball valve return spring.

3. The two-way oil inlet resonance bypass type electric control oil injector according to claim 1 or 2, characterized in that: when the coil is electrified, the balance valve rod moves upwards, the upper cavity of the balance valve rod and the lower cavity of the balance valve rod are in a disconnected state, the oil return hole and the oil tank are in a communicated state, fuel oil in the control cavity returns to the oil tank through the middle oil duct, the middle throttle hole and the oil return hole, the needle valve body is lifted upwards, and the spray hole opens for oil injection; after the coil is powered off, the balance valve rod moves downwards under the action of the electromagnetic valve reset spring and is pressed on the upper end face of the middle block, the upper balance valve rod cavity is communicated with the lower balance valve rod cavity, the oil return hole is disconnected with the oil tank, and meanwhile, fuel in the downlink high-pressure oil way enters the control cavity through the uplink oil inlet hole, the upper balance valve rod cavity, the lower balance valve rod cavity and the middle oil duct on the one hand and enters the control cavity through the oil inlet hole and the oil inlet throttling hole on the other hand.

4. The two-way oil inlet resonance bypass type electric control oil injector according to claim 1 or 2, characterized in that: when the spray hole stops spraying oil, the fuel pressure of the upper end face of the control slide block is higher than that of the lower end face of the control slide block, the control slide block overcomes the pre-tightening force of the return spring of the control slide block to move downwards, the bypass oil way is opened, and the control slide block returns to the initial position under the action force of the return spring of the control slide block along with the fuel entering the control cavity.

5. The two-way oil inlet resonance bypass type electric control oil injector according to claim 3, characterized in that: when the spray hole stops spraying oil, the fuel pressure of the upper end face of the control slide block is higher than that of the lower end face of the control slide block, the control slide block overcomes the pre-tightening force of the return spring of the control slide block to move downwards, the bypass oil way is opened, and the control slide block returns to the initial position under the action force of the return spring of the control slide block along with the fuel entering the control cavity.

6. The two-way oil inlet resonance bypass type electric control oil injector according to claim 1 or 2, characterized in that: the diameter of the middle part of the resonance throttling hole is smaller than the diameters of the two ends of the resonance throttling hole and smaller than the diameter of the resonance through hole, and the total axial length of the resonance throttling hole and the resonance through hole is consistent.

7. The two-way oil inlet resonance bypass type electric control oil injector according to claim 3, characterized in that: the diameter of the middle part of the resonance throttling hole is smaller than the diameters of the two ends of the resonance throttling hole and smaller than the diameter of the resonance through hole, and the total axial length of the resonance throttling hole and the resonance through hole is consistent.

8. The two-way oil inlet resonance bypass type electric control oil injector according to claim 4, characterized in that: the diameter of the middle part of the resonance throttling hole is smaller than the diameters of the two ends of the resonance throttling hole and smaller than the diameter of the resonance through hole, and the total axial length of the resonance throttling hole and the resonance through hole is consistent.

9. The two-way oil inlet resonance bypass type electric control oil injector according to claim 5, characterized in that: the diameter of the middle part of the resonance throttling hole is smaller than the diameters of the two ends of the resonance throttling hole and smaller than the diameter of the resonance through hole, and the total axial length of the resonance throttling hole and the resonance through hole is consistent.