A new type of high pressure common rail injector with built-in pressure accumulator

Abstract

The invention discloses a novel high-pressure common rail fuel injector with a built-in pressure accumulator chamber, comprising a fuel injector body, an electromagnet, a clamping spring and an armature assembly; the electromagnet is fixedly connected to the top of the fuel injector body, a control valve seat is sleeved on the upper end of the fuel injector body, the armature assembly is arranged between the top of the control valve seat and the electromagnet, an energized coil is wound around the outer side of the armature assembly and the energized coil is connected to the electromagnet circuit, a ball valve is arranged at the lower end of the armature assembly, the ball valve is located in a conical cavity and the ball valve contacts the top of the control valve seat, the bottom end of the control valve seat is sleeved on the outer side of the top of the control plunger, a clamping spring is sleeved on the outer side of the bottom end of the control plunger, a fuel nozzle needle valve is arranged below the control plunger, and the bottom end of the clamping spring contacts the fuel nozzle needle valve; the fuel nozzle needle valve is sleeved in the fuel nozzle needle valve seat, a nozzle cap is sleeved on the outer side of the fuel injector needle valve seat, and the nozzle cap is threadedly connected to the bottom end of the fuel injector body.

Description

Technical Field

[0001] The present invention relates to the field of fuel injectors, in particular to a novel high-pressure common rail fuel injector with a built-in pressure accumulator chamber. Background Art

[0002] The high-pressure common rail system is a new generation of electronically controlled diesel engine fuel systems that emerged in the 1990s. With high injection pressures reaching 140-200 MPa and flexible control methods, it is particularly suitable for diesel engines with high emission requirements and low fuel consumption.

[0003] The current high pressure common rail injector structure is as follows Figure 1 shown.

[0004] High-pressure fuel from the high-pressure common rail enters the injector body 6 through the oil inlet passage 601, passes through the oil inlet throttle hole 501 in the control valve seat 5, and enters the control chamber 8 formed by the control plunger 7 and the control valve seat 5. Due to the high fuel pressure of 140-180 MPa, the high-pressure fuel easily leaks from the control chamber 8 through the gap between the control valve seat 5 and the control plunger 7 into the low-pressure chamber 99, and then flows back to the fuel tank through the oil return hole 604 in the injector body 6 and the oil return passage 1.

[0005] Another high-pressure fuel passes through the oil channel hole 602 in the injector body 6 and the needle valve seat oil channel 13 in the injector needle valve seat 11 into the injector oil tank 14. The high-pressure fuel can also easily leak into the low-pressure chamber 8 from the gap between the nozzle needle valve seat 11 and the nozzle needle valve 12. The low-pressure chamber 8 is connected to the low-pressure chamber 99, and then the low-pressure fuel passes through the low-pressure chamber 99 and the oil return hole 604 of the injector body through the oil return hole 1 and flows back to the fuel tank.

[0006] The high-pressure fuel leaked from the above two parts accounts for about 40% of the injector return oil volume. The leakage of high-pressure fuel from the high-pressure chamber to the low-pressure chamber not only causes energy loss, but also causes the common rail injector to overheat. The injector return oil temperature is as high as over 100°C, which can easily lead to faults such as stuck parts, overheating of the injector solenoid coil, and decreased electromagnetic force.

[0007] To reduce high-pressure fuel leakage in common rail injectors, the common approach is to improve machining accuracy and reduce the clearance between components. This not only increases manufacturing costs, but also causes problems such as component seizure, shortening the injector's service life.

[0008] Dr. GanserMarco of Switzerland patented a leak-free injector (US20010013556, US20030052198A1, and US20050072856A1), but the structure is complex. U.S. Patent No. 6928585 (China Patent No. CN101501323A) and EP1990532A1 also utilize similar structures. This type of structure integrates the control plunger and needle valve, with the top surface of the control sleeve surrounding the plunger forming a seal with the bottom surface of the control valve. High-pressure fuel from the common rail is directly channeled into the accumulator through an oil passage in the injector body. Both the control valve and the needle valve are surrounded by high-pressure fuel, eliminating any pressure differential across the gap between the mating components and preventing fuel leakage. However, this structure places stringent requirements on the perpendicularity and offset between the control plunger and the control valve seat. Because the nozzle needle valve's guide hole is relatively far from the lower plane of the control valve seat, machining and assembly errors can cause the control plunger, integrated with the needle valve, to become non-perpendicular to the lower plane of the control valve seat after the nozzle is installed on the injector body. The spring forces the top surface of the control sleeve and the plane of the control valve seat to tilt, creating a gap that compromises the seal for high-pressure fuel. When the control valve is open, high-pressure fuel in the high-pressure oil chamber flows not only through the inlet orifice but also through this gap into the control chamber, altering the throttling ratio between the inlet and outlet orifices and severely impacting injector operation. Furthermore, the control plunger, integrated with the needle valve, is non-perpendicular to the lower plane of the control valve seat, which can easily cause the control plunger to be blocked by lateral forces during movement, leading to stagnation or even freezing, resulting in injector malfunction. Summary of the Invention

[0009] The object of the present invention is to provide a new type of high-pressure common rail injector with a built-in pressure accumulator chamber, which has a simple structure and a low failure rate, in order to solve the above problems.

[0010] In order to achieve the above object, the technical solution of the present invention is:

[0011] A new type of high-pressure common rail fuel injector with a built-in pressure accumulator chamber comprises a hollow fuel injector body and a fuel injection nozzle connected to the lower end of the fuel injector body;

[0012] The fuel injector includes a hollow fuel injector needle valve seat and a fuel injector needle valve disposed inside the fuel injector needle valve seat and reciprocating up and down through the fuel injector needle valve seat to open or close the fuel injector and thereby make the fuel injector spray or not spray fuel. An oil tank is disposed inside the fuel injector;

[0013] The injector body is provided with a control valve seat at the top end of its hollow inner cavity, which forms a seal therewith, and a control plunger located between the control valve seat and the injector nozzle and stationary relative to the injector body. The cavity between the lower portion of the injector body, the injector nozzle, and the control plunger forms a control chamber, and the cavity between the upper portion of the injector body, the control plunger, and the control valve seat forms a pressure accumulation chamber, which serves as a micro common rail pipe integrated into the high-pressure common rail injector.

[0014] The injector body is provided with an oil inlet hole, the control valve seat is provided with an oil inlet throttling hole and an oil outlet throttling hole, the pressure accumulator chamber is connected with the oil inlet hole outside and is connected with the oil tank inside; the control plunger is provided with a slender hole along the length direction, the slender hole is connected with the control chamber at the bottom and is connected with the oil inlet throttling hole and the oil outlet throttling hole of the control valve seat at the top, and the outlet of the oil outlet throttling hole is provided with a control component for controlling the opening or closing of the oil outlet throttling hole.

[0015] When the high-pressure fuel coming out of the common rail pipe enters the oil inlet hole on the injector body and enters the pressure accumulation chamber in the injector body, part of the fuel enters the control chamber through the oil inlet throttle hole on the control valve seat and the slender hole on the control plunger, and the other part of the fuel enters the injector nozzle through the pressure accumulation chamber.

[0016] When the control assembly is not working, the spring in the control assembly applies pressure, pressing the ball valve tightly against the high-precision conical surface of the control valve seat. The oil outlet throttle hole of the control valve seat is closed, and the high-pressure fuel stops in the control chamber and does not flow. The high-pressure fuel in the control chamber presses the injector needle valve tightly against the seat surface of the injector needle valve seat, and the injector does not spray fuel.

[0017] When the control ball valve in the control assembly leaves the high-precision conical surface of the control valve seat, the high-pressure fuel in the control chamber flows through the elongated hole in the control plunger and the oil outlet orifice in the control valve seat, then over the high-precision sealing conical surface. The high-pressure fuel is then reduced to low-pressure oil and returned to the fuel tank through the oil return passage. The discharge of high-pressure fuel from the control chamber reduces the fuel pressure in the control chamber, causing the injector needle valve to disengage from the seat surface of the injector needle valve seat. The high-pressure fuel in the injector reservoir is then sprayed through the injector nozzle orifice into the engine combustion chamber, and the injector begins spraying.

[0018] The above structures constitute a closed loop system, which enables the high pressure common rail injector of the present invention to complete the injection work. The above structures are indispensable. Without one structure, the work of the injector cannot be completed.

[0019] A pressure accumulator is provided inside the injector body, which is equivalent to integrating a miniature common rail tube inside the injector body. When the injector is used in the high-pressure common rail system of a single-cylinder / two-cylinder diesel engine with small horsepower, the micro common rail tube integrated inside the injector can be used to replace the common rail tube components in the original diesel engine high-pressure common rail system. The injector becomes a common rail injector with integrated high-pressure common rail tube components, which simplifies the high-pressure common rail system of a single-cylinder / two-cylinder diesel engine with small horsepower, and greatly reduces the cost of the diesel engine high-pressure common rail system.

[0020] The high-pressure fuel in the accumulator acts as a pressure stabilizer, balancing pressure fluctuations during the injector's injection process. During injector operation, the control plunger does not move, significantly reducing machining and assembly precision requirements for the control valve seat, control plunger, and injector body bore, particularly the coaxiality requirements. This improves injector production efficiency.

[0021] Furthermore, above the oil tank, a mating structure is formed between the nozzle needle valve and the nozzle needle valve seat; between the control chamber and the pressure accumulation chamber, a mating structure is formed between the control plunger and the injector body; above the pressure accumulation chamber, the control plunger and the center hole of the control valve seat form a mating structure.

[0022] Because the high-pressure fuel pressure in the accumulator and control chambers of the injector body is the same, the high-pressure fuel in the control chamber will not flow into the accumulator through the clearance between the control valve seat and the control plunger, or between the injector body and the control plunger. Similarly, the high-pressure fuel in the injector nozzle sump will not flow into the control chamber through the clearance between the injector needle valve and the injector needle valve seat. Therefore, even if the high-pressure common rail fuel pressure is as high as 160-180MPa, the local high-pressure fuel pressure in the injector body is the same, preventing high-pressure fuel leakage, greatly reducing fuel leakage from the high-pressure common rail injector.

[0023] Furthermore, the hollow interior of the injector body is provided with an inner plane, and the control valve seat is positioned on the inner plane to form an end-face seal with the inner plane of the injector body, which is tightened by a lock nut screwed onto the injector body. The control valve seat is provided with an inner conical surface at the outlet of the oil outlet orifice. The control assembly includes a ball valve pressed against the inner conical surface and an electromagnetic mechanism capable of controlling the longitudinal movement of the ball valve. The electromagnetic mechanism includes an electromagnet and an armature assembly.

[0024] Furthermore, a connecting sleeve or push rod is provided at the top of the injector needle valve, which is arranged between the bottom end of the control plunger and the top end of the injector needle valve. Both ends of the control plunger are provided with oil drain grooves that extend transversely through the side wall of the control plunger. The oil drain grooves are connected to the elongated hole, and the oil drain grooves and the side oil passages are both horizontal grooves or oblique through holes.

[0025] Compared with the prior art, the present invention has the following advantages and positive effects:

[0026] The present invention moves the control chamber down to the top of the fuel nozzle, and directly drives the opening and closing of the nozzle needle valve through the pressure change in the control chamber, thereby controlling the plunger to remain stationary within the injector body. Furthermore, an elongated hole is provided in the control plunger, through which the high-pressure fuel in the control chamber is replenished and discharged, thereby changing the fuel pressure in the control chamber. Simultaneously, the present invention provides a pressure accumulator chamber inside the injector as an integrated high-pressure fuel accumulator, which can significantly reduce injection pressure fluctuations during the injection process and improve pressure stability during the injection process.

[0027] On the other hand, the present invention is provided with three mating parts inside, namely, the mating between the inner wall of the bottom end of the control valve seat and the outer wall of the top end of the control plunger, the mating between the outer wall of the control plunger and the inner wall of the injector body, and the mating between the nozzle needle valve and the injector needle valve seat. However, both sides of the mating parts of these three places are high-pressure fuel, and there is no high and low pressure difference at both ends of the mating parts gap, so there is no high-pressure fuel leakage, eliminating the static leakage of the injector, greatly reducing the return oil of the injector, and reducing the operating temperature of the injector; at the same time, the control plunger corresponding to the mating between the outer wall of the control plunger and the inner wall of the injector body, and the mating between the nozzle needle valve and the injector needle valve seat is in the working process of the injector. It does not move, so even if the cooperation of the two parts is stuck or jammed due to problems in the processing or assembly accuracy of the parts, it will not affect the normal operation of the injector, which greatly reduces the processing and assembly accuracy requirements of the injector and reduces the failure rate of the injector; and there is no fuel leakage below the control valve seat in the injector body, and there is no need to set the original oil return hole. At the same time, the high-pressure fuel of the injector is stored in the accumulator chamber. It is only necessary to introduce the high-pressure fuel from the accumulator chamber into the injector nozzle through the oil channel hole of the injector body, shortening the original oil channel hole. Since the oil return hole and oil channel hole in the injector body are changed, the processing difficulty of the injector body is greatly reduced, thereby improving the production efficiency of the injector. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 It is the prior art structure diagram of the fuel injector;

[0030] Figure 2 It is a structural diagram of the first embodiment;

[0031] Figure 3 for Figure 2 A magnified view of the local structure;

[0032] Figure 4 is a schematic structural diagram of the second embodiment;

[0033] Figure 5 is a schematic structural diagram of a third embodiment;

[0034] Figure 6 is a partial structural diagram of the fourth embodiment;

[0035] Figure 7 It is a partial structural diagram of the fifth embodiment. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts, any modifications, equivalent replacements, improvements, etc., shall be included in the scope of protection of the present invention.

[0037] Example 1, as Figure 2 、 Figure 3 As shown, the new high-pressure common rail injector with a built-in pressure accumulator in this embodiment includes an injector body 6, an electromagnet 2, a compression spring 10, an armature assembly 3, a ball valve 4, a control valve seat 5, and a nozzle cap 15;

[0038] The electromagnet 2 is fixedly connected to the top of the injector body 6. The electromagnet 2 and the armature assembly constitute an electromagnetic mechanism. The control valve seat 5 is sleeved on the top of the injector body 6 and is sealed with the control valve seat 5. The top of the injector body 6 is internally threaded with a lock nut 17. The lock nut 17 is set at the top of the control valve seat 5. The top of the control valve seat 5 is provided with a conical cavity, which is connected to the oil return channel 1 set on the electromagnet 2. The bottom of the conical cavity is provided with an oil outlet throttling hole 502 that longitudinally penetrates the control valve seat.

[0039] The armature assembly 3 is arranged between the top of the control valve seat 5 and the electromagnet 2. The outer side of the armature assembly 3 is wound with an energized coil, and the energized coil is connected to the electromagnet 2. The lower end of the armature assembly 3 is provided with a ball valve 4.

[0040] The armature assembly 3 includes an upper guide sleeve 303, a lower guide sleeve 302, an elastic member, and an armature rod 301. The energized coil is wound around the outer sides of the upper guide sleeve 303 and the lower guide sleeve 302. The elastic member is arranged at the top end of the armature rod 301. The upper end surface of the elastic member contacts the electromagnet 2, and the lower end surface of the elastic member contacts the top end of the armature rod 301. The armature rod 301 is sleeved in the upper guide sleeve 303 and the lower guide sleeve 302 and the armature rod 301 can slide relative to the upper guide sleeve 303 and the lower guide sleeve 302. The bottom end of the armature rod 301 contacts the ball valve 4.

[0041] The ball valve 4 is located in the conical cavity and contacts the high-precision conical surface of the control valve seat. The bottom end of the control valve seat 5 is sleeved on the outside of the top end of the control plunger 7 to form a pair of parts. An elongated hole 702 is provided at the center of the control plunger 7. A side oil channel 701 connected to the elongated hole 702 is provided on the side of the top end of the control plunger 7. The top of the elongated hole 702 is connected to the oil outlet throttling hole 502. The side oil channel 701 is connected to the oil inlet hole 601 provided on the side of the injector body 6 through the oil inlet throttling hole 501 that transversely passes through the side wall of the control valve seat 5. A pressure accumulation chamber 9 is provided between the inner wall of the injector body 6 and the outer wall of the control plunger 7. The oil inlet hole 601 is connected to the pressure accumulation chamber 9. An oil channel hole 602 is provided in the injector body 6. One end of the oil channel hole 602 is connected to the pressure accumulation chamber 9, and the other end of the oil channel hole 602 is connected to the valve seat oil hole 13 provided in the needle valve seat 11 of the injector nozzle;

[0042] The bottom end of the control plunger 7 is connected to a compression spring 10, and a nozzle needle valve 12 is provided below the control plunger 7. A control chamber 8 is provided between the outer wall of the bottom end of the control plunger 7, the outer wall of the top end of the nozzle needle valve 12, and the inner wall of the injector body 6. The top end of the compression spring 10 contacts the top end of the control chamber 8 or the limiting step provided on the side of the control plunger 7, and the bottom end of the compression spring 10 contacts the connecting sleeve 16 fixedly sleeved on the outer side of the top end of the nozzle needle valve 12; the connecting sleeve is annular and fixedly sleeved on the outer side of the top end of the nozzle needle valve 12;

[0043] The nozzle needle valve 12 is arranged in the nozzle needle valve seat 11. A nozzle oil storage groove 14 is provided between the inner wall of the injector needle valve seat 11 and the outer wall of the injector needle valve 12. The nozzle oil storage groove 14 is connected to the needle valve seat oil hole 13. The bottom end of the injector needle valve seat 11 is provided with a nozzle spray hole 1102. The outer side of the injector needle valve seat 11 is sleeved with a nozzle tight cap 15, and the nozzle tight cap 15 is threadedly connected to the bottom end of the injector body 6.

[0044] Example 2, as Figure 4 As shown, the new high-pressure common rail injector with a built-in pressure accumulator in this embodiment includes an injector body 6, an electromagnet 2, a compression spring 10, an armature assembly 3, a ball valve 4, a control valve seat 5, and a nozzle cap 15;

[0045] The electromagnet 2 is fixedly connected to the top of the injector body 6. The control valve seat 5 is sleeved on the top of the injector body 6 and is sealed with the control valve seat 5. The top of the injector body 6 is internally threaded with a lock nut 17. The lock nut 17 is set at the top of the control valve seat 5. The top of the control valve seat 5 is provided with a conical cavity, which is connected to the oil return channel 1 set on the side of the injector body 6. The bottom of the conical cavity is provided with an oil outlet throttling hole 502 that longitudinally penetrates the control valve seat.

[0046] The armature assembly 3 is arranged between the top of the control valve seat 5 and the electromagnet 2. The outer side of the armature assembly 3 is wound with an energized coil, and the energized coil is connected to the electromagnet 2. The lower end of the armature assembly 3 is provided with a ball valve 4.

[0047] The armature assembly 3 includes an upper guide sleeve 303, a lower guide sleeve 302, a spring, and an armature rod 301. The energized coil is wound around the outer side of the lower guide sleeve 302. The armature rod 301 is sleeved in the upper guide sleeve 303 and the lower guide sleeve 302. The upper guide sleeve 303 is fixedly connected to the armature rod 301. The lower guide sleeve 302 is slidably connected to the armature rod 301. The spring is sleeved on the outer side of the armature rod 301 and is located between the upper guide sleeve 303 and the lower guide sleeve 302. The bottom end of the armature rod 301 is in contact with the ball valve 4.

[0048] The ball valve 4 is located in the conical cavity and contacts the high-precision conical surface of the control valve seat. The bottom end of the control valve seat 5 is sleeved on the outside of the top end of the control plunger 7 to form a pair of parts. An elongated hole 702 is provided at the center of the control plunger 7. A side oil channel 701 connected to the elongated hole 702 is provided on the side of the top end of the control plunger 7. The top of the elongated hole 702 is connected to the oil outlet throttling hole 502. The side oil channel 701 is connected to the oil inlet hole 601 provided on the side of the injector body 6 through the oil inlet throttling hole 501 that transversely passes through the side wall of the control valve seat 5. A pressure accumulation chamber 9 is provided between the inner wall of the injector body 6 and the outer wall of the control plunger 7. The oil inlet hole 601 is connected to the pressure accumulation chamber 9. An oil channel hole 602 is provided in the injector body 6. One end of the oil channel hole 602 is connected to the pressure accumulation chamber 9, and the other end of the oil channel hole 602 is connected to the valve seat oil hole 13 provided in the needle valve seat 11 of the injector nozzle;

[0049] The bottom end of the control plunger 7 is connected to a compression spring 10, and a nozzle needle valve 12 is provided below the control plunger 7. A control chamber 8 is provided between the outer wall of the bottom end of the control plunger 7, the outer wall of the top end of the nozzle needle valve 12, and the inner wall of the injector body 6. The top end of the compression spring 10 contacts the top end of the control chamber 8 or the limiting step provided on the side of the control plunger 7, and the bottom end of the compression spring 10 contacts the connecting sleeve 16 fixedly sleeved on the outer side of the top end of the nozzle needle valve 12; the connecting sleeve is annular and fixedly sleeved on the outer side of the top end of the nozzle needle valve 12;

[0050] The nozzle needle valve 12 is arranged in the nozzle needle valve seat 11. A nozzle oil storage groove 14 is provided between the inner wall of the injector needle valve seat 11 and the outer wall of the injector needle valve 12. The nozzle oil storage groove 14 is connected to the needle valve seat oil hole 13. The bottom end of the injector needle valve seat 11 is provided with a nozzle spray hole 1102. The outer side of the injector needle valve seat 11 is sleeved with a nozzle tight cap 15, and the nozzle tight cap 15 is threadedly connected to the bottom end of the injector body 6.

[0051] Example 3, as Figure 5As shown, the new high-pressure common rail injector with a built-in pressure accumulator in this embodiment includes an injector body 6, an electromagnet 2, a compression spring 10, an armature assembly 3, a ball valve 4, a control valve seat 5, and a nozzle cap 15;

[0052] The electromagnet 2 is fixedly connected to the top of the injector body 6. The control valve seat 5 is sleeved on the top of the injector body 6 and is sealed with the control valve seat 5. The top of the injector body 6 is internally threaded with a lock nut 17. The lock nut 17 is set at the top of the control valve seat 5. The top of the control valve seat 5 is provided with a conical cavity, which is connected to the oil return channel 1 set on the side of the injector body 6. The bottom of the conical cavity is provided with an oil outlet throttling hole 502 that longitudinally penetrates the control valve seat.

[0053] The armature assembly 3 is arranged between the top of the control valve seat 5 and the electromagnet 2. The outer side of the armature assembly 3 is wound with an energized coil, and the energized coil is connected to the electromagnet 2. The lower end of the armature assembly 3 is provided with a ball valve 4.

[0054] The armature assembly 3 includes a guide sleeve 303, a spring, and an armature rod 301. The energized coil is wound around the outside of the guide sleeve 303, the armature rod 301 is sleeved in the guide sleeve 303, and the spring is sleeved on the outside of the top end of the armature rod 301. The upper end surface of the spring contacts the electromagnet 2, the lower end surface of the spring contacts the limit platform set at the top end of the armature rod 301, and the bottom end of the armature rod 301 contacts the ball valve 4.

[0055] The ball valve 4 is located in the conical cavity and contacts the high-precision conical surface of the control valve seat. The bottom end of the control valve seat 5 is sleeved on the outside of the top end of the control plunger 7 to form a pair of parts. An elongated hole 702 is provided at the center of the control plunger 7. A side oil channel 701 connected to the elongated hole 702 is provided on the side of the top end of the control plunger 7. The top of the elongated hole 702 is connected to the oil outlet throttling hole 502. The side oil channel 701 is connected to the oil inlet hole 601 provided on the side of the injector body 6 through the oil inlet throttling hole 501 that transversely passes through the side wall of the control valve seat 5. A pressure accumulation chamber 9 is provided between the inner wall of the injector body 6 and the outer wall of the control plunger 7. The oil inlet hole 601 is connected to the pressure accumulation chamber 9. An oil channel hole 602 is provided in the injector body 6. One end of the oil channel hole 602 is connected to the pressure accumulation chamber 9, and the other end of the oil channel hole 602 is connected to the valve seat oil hole 13 provided in the needle valve seat 11 of the injector nozzle;

[0056] The bottom end of the control plunger 7 is connected to a compression spring 10, and a nozzle needle valve 12 is provided below the control plunger 7. A control chamber 8 is provided between the outer wall of the bottom end of the control plunger 7, the outer wall of the top end of the nozzle needle valve 12, and the inner wall of the injector body 6. The top end of the compression spring 10 contacts the top end of the control chamber 8 or the limiting step provided on the side of the control plunger 7, and the bottom end of the compression spring 10 contacts the connecting sleeve 16 fixedly sleeved on the outer side of the top end of the nozzle needle valve 12; the connecting sleeve is annular and fixedly sleeved on the outer side of the top end of the nozzle needle valve 12;

[0057] The nozzle needle valve 12 is arranged in the nozzle needle valve seat 11. A nozzle oil storage groove 14 is provided between the inner wall of the injector needle valve seat 11 and the outer wall of the injector needle valve 12. The nozzle oil storage groove 14 is connected to the needle valve seat oil hole 13. The bottom end of the injector needle valve seat 11 is provided with a nozzle spray hole 1102. The outer side of the injector needle valve seat 11 is sleeved with a nozzle tight cap 15, and the nozzle tight cap 15 is threadedly connected to the bottom end of the injector body 6.

[0058] Example 4: Figure 2 、 Figure 3 、 Figure 6 As shown, the novel high-pressure common rail injector with a built-in pressure accumulator in this embodiment changes the structure of the connecting sleeve 16 in Example 1, and includes an injector body 6, an electromagnet 2, a compression spring 10, an armature assembly 3, a ball valve 4, a control valve seat 5, and a nozzle cap 15;

[0059] The electromagnet 2 is fixedly connected to the top of the injector body 6. The control valve seat 5 is sleeved on the top of the injector body 6 and is sealed with the control valve seat 5. The top of the injector body 6 is internally threaded with a lock nut 17. The lock nut 17 is set on the top of the control valve seat 5. The top of the control valve seat 5 is provided with a conical cavity, which is connected to the oil return channel 1 provided on the electromagnet 2. The bottom of the conical cavity is provided with an oil outlet throttling hole 502 that longitudinally penetrates the control valve seat.

[0060] The armature assembly 3 is arranged between the top of the control valve seat 5 and the electromagnet 2. The outer side of the armature assembly 3 is wound with an energized coil, and the energized coil is connected to the electromagnet 2. The lower end of the armature assembly 3 is provided with a ball valve 4.

[0061] The armature assembly 3 includes an upper guide sleeve 303, a lower guide sleeve 302, an elastic member, and an armature rod 301. The energized coil is wound around the outer sides of the upper guide sleeve 303 and the lower guide sleeve 302. The elastic member is arranged at the top end of the armature rod 301. The upper end surface of the elastic member contacts the electromagnet 2, and the lower end surface of the elastic member contacts the top end of the armature rod 301. The armature rod 301 is sleeved in the upper guide sleeve 303 and the lower guide sleeve 302 and the armature rod 301 can slide relative to the upper guide sleeve 303 and the lower guide sleeve 302. The bottom end of the armature rod 301 contacts the ball valve 4.

[0062] The ball valve 4 is located in the conical cavity and contacts the high-precision conical surface of the control valve seat. The bottom end of the control valve seat 5 is sleeved on the outside of the top end of the control plunger 7 to form a pair of parts. An elongated hole 702 is provided at the center of the control plunger 7. A side oil channel 701 connected to the elongated hole 702 is provided on the side of the top end of the control plunger 7. The top of the elongated hole 702 is connected to the oil outlet throttling hole 502. The side oil channel 701 is connected to the oil inlet hole 601 provided on the side of the injector body 6 through the oil inlet throttling hole 501 that transversely passes through the side wall of the control valve seat 5. A pressure accumulation chamber 9 is provided between the inner wall of the injector body 6 and the outer wall of the control plunger 7. The oil inlet hole 601 is connected to the pressure accumulation chamber 9. An oil channel hole 602 is provided in the injector body 6. One end of the oil channel hole 602 is connected to the pressure accumulation chamber 9, and the other end of the oil channel hole 602 is connected to the valve seat oil hole 13 provided in the needle valve seat 11 of the injector nozzle;

[0063] The bottom end of the control plunger 7 is connected to a compression spring 10, and a nozzle needle valve 12 is provided below the control plunger 7. A control chamber 8 is provided between the outer wall of the bottom end of the control plunger 7, the outer wall of the top end of the nozzle needle valve 12, and the inner wall of the injector body 6. The top end of the compression spring 10 contacts the top end of the control chamber 8 or the limiting step provided on the side of the control plunger 7, and the bottom end of the compression spring 10 contacts the connecting sleeve 16 sleeved on the outer side of the top end of the nozzle needle valve 12; the connecting sleeve 16 is tubular, and the top end of the connecting sleeve 16 contacts the bottom end of the compression spring 10. A limiting step is provided on the inner side wall of the bottom end of the connecting sleeve 16. After the connecting sleeve 16 is sleeved on the top end of the nozzle needle valve 12, the lower end surface of the limiting step contacts the top end of the nozzle needle valve 12.

[0064] The nozzle needle valve 12 is arranged in the nozzle needle valve seat 11. A nozzle oil storage groove 14 is provided between the inner wall of the injector needle valve seat 11 and the outer wall of the injector needle valve 12. The nozzle oil storage groove 14 is connected to the needle valve seat oil hole 13. The bottom end of the injector needle valve seat 11 is provided with a nozzle spray hole 1102. The outer side of the injector needle valve seat 11 is sleeved with a nozzle tight cap 15, and the nozzle tight cap 15 is threadedly connected to the bottom end of the injector body 6.

[0065] Example 5: Figure 2 、 Figure 3 、 Figure 7 As shown, the novel high-pressure common rail injector with a built-in pressure accumulator in this embodiment changes the structure of the control plunger 7 in Example 1, and includes an injector body 6, an electromagnet 2, a compression spring 10, an armature assembly 3, a ball valve 4, a control valve seat 5, and a nozzle cap 15;

[0066] The electromagnet 2 is fixedly connected to the top of the injector body 6. The control valve seat 5 is sleeved on the top of the injector body 6 and is sealed with the control valve seat 5. The top of the injector body 6 is internally threaded with a lock nut 17. The lock nut 17 is set on the top of the control valve seat 5. The top of the control valve seat 5 is provided with a conical cavity, which is connected to the oil return channel 1 provided on the electromagnet 2. The bottom of the conical cavity is provided with an oil outlet throttling hole 502 that longitudinally penetrates the control valve seat.

[0067] The armature assembly 3 is arranged between the top of the control valve seat 5 and the electromagnet 2. The outer side of the armature assembly 3 is wound with an energized coil, and the energized coil is connected to the electromagnet 2. The lower end of the armature assembly 3 is provided with a ball valve 4.

[0068] The armature assembly 3 includes an upper guide sleeve 303, a lower guide sleeve 302, an elastic member, and an armature rod 301. The energized coil is wound around the outer sides of the upper guide sleeve 303 and the lower guide sleeve 302. The elastic member is arranged at the top end of the armature rod 301. The upper end surface of the elastic member contacts the electromagnet 2, and the lower end surface of the elastic member contacts the top end of the armature rod 301. The armature rod 301 is sleeved in the upper guide sleeve 303 and the lower guide sleeve 302 and the armature rod 301 can slide relative to the upper guide sleeve 303 and the lower guide sleeve 302. The bottom end of the armature rod 301 contacts the ball valve 4.

[0069] The ball valve 4 is located in the conical cavity and contacts the high-precision conical surface of the control valve seat. The bottom end of the control valve seat 5 is sleeved on the outside of the top end of the control plunger 7. The center of the control plunger 7 is provided with an elongated hole 702. The top side of the control plunger 7 is provided with a side oil channel 701 connected to the elongated hole 702. The top of the elongated hole 702 is connected to the oil outlet throttling hole 502. The side oil channel 701 is connected to the oil inlet hole 601 provided on the side of the injector body 6 through the oil inlet throttling hole 501 that transversely penetrates the side wall of the control valve seat 5. The bottom of the control plunger 7 is connected to the oil inlet 601 provided on the side of the injector body 6. An oil drain groove 705 is provided at the end thereof, which extends transversely through the side wall of the control plunger. The oil drain groove 705 is connected to the elongated hole 702. The axial directions of the oil drain groove 705 and the side oil passage 701 are both horizontal or inclined. A pressure accumulator chamber 9 is provided between the inner side wall of the injector body 6 and the outer side wall of the control plunger 7. The oil inlet hole 601 is connected to the pressure accumulator chamber 9. An oil passage hole 602 is provided in the injector body 6. One end of the oil passage hole 602 is connected to the pressure accumulator chamber 9, and the other end of the oil passage hole 602 is connected to the valve seat oil hole 13 provided in the needle valve seat 11 of the injector nozzle.

[0070] The bottom end of the control plunger 7 is connected to a compression spring 10, and a nozzle needle valve 12 is provided below the control plunger 7. A control chamber 8 is provided between the outer wall of the bottom end of the control plunger 7, the outer wall of the top end of the nozzle needle valve 12, and the inner wall of the injector body 6. The top end of the compression spring 10 contacts the top end of the control chamber 8 or the limiting step provided on the side of the control plunger 7, and the bottom end of the compression spring 10 contacts the connecting sleeve 16 fixedly sleeved on the outer side of the top end of the nozzle needle valve 12; the connecting sleeve is annular and fixedly sleeved on the outer side of the top end of the nozzle needle valve 12;

[0071] The nozzle needle valve 12 is arranged in the nozzle needle valve seat 11. A nozzle oil storage groove 14 is provided between the inner wall of the injector needle valve seat 11 and the outer wall of the injector needle valve 12. The nozzle oil storage groove 14 is connected to the needle valve seat oil hole 13. The bottom end of the injector needle valve seat 11 is provided with a nozzle spray hole 1102. The outer side of the injector needle valve seat 11 is sleeved with a nozzle tight cap 15, and the nozzle tight cap 15 is threadedly connected to the bottom end of the injector body 6.

[0072] The high-pressure common rail injector in the above embodiment mainly includes: an electromagnet 2, an armature assembly 3, a ball valve 4, a locking nut 17, a control valve seat 5, an injector body 6, a control plunger 7, a compression spring 10, a fuel injector nozzle (including a fuel injector needle valve seat 11 and a fuel injector needle valve 12), a fuel injector cap 15, a connecting sleeve 16, etc.

[0073] The nozzle cap 15 presses the nozzle needle valve seat 11 against the lower end surface of the injector body 6. The compression spring 10 presses the control plunger 7 upward until its upper end abuts the inner end surface of the control valve seat 5. The lower end of the compression spring 10, through the connecting sleeve 16, presses the nozzle needle valve 12 against the nozzle needle valve seat 11. The lock nut 17 presses the control valve seat 5 against the inner surface 603 of the injector body 6. The armature rod 301, under the action of the solenoid spring, presses the ball valve 4 against the high-precision conical surface of the control valve seat 5, closing the oil outlet throttle hole 502 of the control valve seat 5.

[0074] A sealed control chamber 8 is formed between the control plunger 7 and the injector body 6 , the injector needle valve seat 11 and the injector needle valve 12 .

[0075] The working principle of the leak-free high-pressure common rail injector in the embodiment is as follows:

[0076] When the high-pressure fuel coming out of the common rail pipe enters the oil inlet hole 601 on the injector body 6 and enters the pressure accumulation chamber 9 in the injector body 6, part of the fuel enters the control chamber 8 through the oil inlet throttle hole 501 on the control valve seat and the side oil channel 701 and the slender hole 702 on the control plunger 7, and the other part of the fuel enters the needle valve seat oil hole 13 on the needle valve seat 11 of the injector nozzle through the oil channel hole 602 on the injector body, and the fuel enters the oil tank 14 of the injector nozzle through the needle valve seat oil hole 13.

[0077] When the electromagnet 2 is not energized, the ball valve 4 is pressed tightly against the high-precision conical surface of the control valve seat 5 by the armature rod 301 under the action of the elastic member. The oil outlet throttle hole 502 of the control valve seat is closed, and the high-pressure fuel stops in the control chamber 8 and does not flow. The high-pressure fuel in the control chamber 8 presses the nozzle needle valve 12 against the seat surface 1101 of the nozzle needle valve seat 11. At this time, the injector does not spray fuel.

[0078] Because the high-pressure fuel pressures in the accumulator chamber 9 and the control chamber 8 within the injector body are the same, the high-pressure fuel in the control chamber 8 will not flow into the accumulator chamber 9 through the gap between the mating structure 703 between the control valve seat 5 and the control plunger 7, or through the gap between the mating structure 704 between the injector body 6 and the control plunger 7. Similarly, the high-pressure fuel in the injector nozzle sump 14 will not flow into the control chamber 8 through the gap between the mating structure 1201 between the injector needle valve 12 and the injector needle valve seat 11. Therefore, even if the high-pressure common rail fuel pressure reaches as high as 160-180 MPa, the local high-pressure fuel pressure within the injector body 6 is consistent, preventing high-pressure fuel leakage and significantly reducing fuel leakage from the common rail injector.

[0079] When electromagnet 2 is energized, armature rod 301 moves upward, causing ball valve 4 to separate from the high-precision conical surface of control valve seat 5. High-pressure fuel in control chamber 8 flows through elongated hole 702 in control plunger 7 and oil outlet orifice 502 in control valve seat 5, passing over the high-precision sealing conical surface. The high-pressure fuel is then released into low-pressure oil and returned to the fuel tank via oil return passage 1. The discharge of high-pressure fuel from control chamber 8 reduces the fuel pressure in control chamber 8. The high-pressure fuel in injector oil reservoir 14 pushes injector needle valve 12 upward, overcoming the spring force of compression spring 10 above connecting sleeve 16. This lifts injector needle valve 12 off seat surface 1101 of injector needle valve seat 11. The high-pressure fuel in injector oil reservoir 14 is then sprayed through injector nozzle orifice 1102 into the engine combustion chamber, and the injector begins fuel injection.

[0080] A pressure accumulator chamber 9 is provided inside the injector body, which is equivalent to integrating a micro common rail pipe inside the injector body. When the injector is used in a high-pressure common rail system of a small-horsepower diesel engine such as a single-cylinder / two-cylinder, the micro common rail pipe integrated inside the injector can be used to replace the common rail pipe component in the original diesel engine high-pressure common rail system. The injector becomes a common rail injector with an integrated high-pressure common rail pipe component, which simplifies the high-pressure common rail system of a small-horsepower diesel engine such as a single-cylinder / two-cylinder, and greatly reduces the cost of the diesel engine high-pressure common rail system.

[0081] The high-pressure fuel in the accumulator chamber 9 stabilizes the pressure, balancing pressure fluctuations during the injector's injection process. During injector operation, the control plunger 7 does not move. Therefore, the machining and assembly precision requirements for the control valve seat 5, the control plunger 7, and the injector body 6 are significantly reduced, particularly the coaxiality requirements. This improves injector production efficiency.

[0082] While conventional control plungers (also known as valve stems) reciprocate at high speed during injector operation, the control plunger employed in the common rail injector of the present invention remains stationary. The control plunger is internally provided with an elongated hole extending from one end to the other, allowing the high-pressure fuel to flow through.

[0083] The present invention moves the control chamber down to the top of the fuel nozzle, and directly drives the opening and closing of the nozzle needle valve through the pressure change in the control chamber, thereby controlling the plunger to remain stationary within the injector body. Furthermore, an elongated hole is provided in the control plunger, through which the high-pressure fuel in the control chamber is replenished and discharged, thereby changing the fuel pressure in the control chamber. Simultaneously, the present invention provides a pressure accumulator chamber inside the injector as an integrated high-pressure fuel accumulator, which can significantly reduce injection pressure fluctuations during the injection process and improve pressure stability during the injection process.

[0084] On the other hand, the present invention is provided with three mating parts inside, namely, the mating between the inner wall of the bottom end of the control valve seat and the outer wall of the top end of the control plunger, the mating between the outer wall of the control plunger and the inner wall of the injector body, and the mating between the nozzle needle valve and the injector needle valve seat. However, both sides of the mating parts of these three places are high-pressure fuel, and there is no high and low pressure difference at both ends of the mating parts gap, so there is no high-pressure fuel leakage, eliminating the static leakage of the injector, greatly reducing the return oil of the injector, and reducing the operating temperature of the injector; at the same time, the control plunger corresponding to the mating between the outer wall of the control plunger and the inner wall of the injector body, and the mating between the nozzle needle valve and the injector needle valve seat is in the working process of the injector. It does not move, so even if the cooperation of the two parts is stuck or jammed due to problems in the processing or assembly accuracy of the parts, it will not affect the normal operation of the injector, which greatly reduces the processing and assembly accuracy requirements of the injector and reduces the failure rate of the injector; and there is no fuel leakage below the control valve seat in the injector body, and there is no need to set the original oil return hole. At the same time, the high-pressure fuel of the injector is stored in the accumulator chamber. It is only necessary to introduce the high-pressure fuel from the accumulator chamber into the injector nozzle through the oil channel hole of the injector body, shortening the original oil channel hole. Since the oil return hole and oil channel hole in the injector body are changed, the processing difficulty of the injector body is greatly reduced, thereby improving the production efficiency of the injector.

Claims

1. A new type of high-pressure common rail fuel injector with a built-in pressure accumulator, comprising a hollow fuel injector body and a fuel injector nozzle connected to the lower end of the fuel injector body; the fuel injector nozzle comprises a hollow fuel injector needle valve seat and a fuel injector needle valve disposed inside the fuel injector needle valve seat and reciprocating up and down through the fuel injector needle valve seat to open or close the fuel injector nozzle and thus make the fuel injector spray or not spray fuel, and an oil storage tank is disposed inside the fuel injector nozzle; Features: The injector body is provided with a control valve seat which forms a seal therewith and a control plunger which is located between the control valve seat and the injector nozzle and is stationary relative to the injector body at the top of its hollow inner cavity; the injector body forms a control chamber in the cavity between the lower part, the injector nozzle and the control plunger, and the injector sprays fuel through the pressure change in the control chamber; and forms a pressure storage chamber in the cavity between the upper part, the control plunger and the control valve seat as a miniature common rail pipe integrated inside the high-pressure common rail injector, which plays a role in stabilizing the injection pressure; The injector body is provided with an oil inlet hole, the control valve seat is provided with an oil inlet throttling hole and an oil outlet throttling hole, the pressure accumulator chamber is connected with the oil inlet hole outside and connected with the oil storage tank inside; the control plunger is provided with an elongated hole through it along the length direction, the elongated hole is connected with the control chamber at the bottom and connected with the oil inlet throttling hole and the oil outlet throttling hole at the top, and the outlet of the oil outlet throttling hole is provided with a control component for controlling the opening or closing of the oil outlet throttling hole.

2. The novel high-pressure common rail injector with built-in pressure accumulator as claimed in claim 1 is characterized in that: Above the oil tank, a mating structure is formed between the nozzle needle valve and the nozzle needle valve seat; between the control chamber and the pressure accumulation chamber, a mating structure is formed between the control plunger and the injector body; above the pressure accumulation chamber, the control plunger and the inner hole of the control valve seat form a mating structure.

3. The novel high pressure common rail injector with built-in pressure accumulator as claimed in claim 2 is characterized in that: The top of the hollow inner cavity of the injector body is provided with an inner plane, the control valve seat is arranged on the inner plane to form an end face seal with the inner plane of the injector body, and is tightened by a locking nut screwed on the injector body, and the control valve seat is provided with an inner conical surface at the outlet of the oil outlet throttling hole; the control component includes a ball valve pressed on the inner conical surface and an electromagnetic mechanism capable of controlling the longitudinal movement of the ball valve.

4. The novel high-pressure common rail injector with built-in pressure accumulator as claimed in claim 3 is characterized in that: The top end of the nozzle needle valve is provided with a connecting sleeve or a push rod, and the connecting sleeve or the push rod is arranged between the bottom end of the control plunger and the top end of the nozzle needle valve.

5. The novel high-pressure common rail injector with built-in pressure accumulator as claimed in claim 4 is characterized in that: Both ends of the control plunger are provided with oil drain grooves which transversely penetrate the side wall of the control plunger. The oil drain grooves are connected with the elongated hole. The oil drain grooves are horizontal grooves or oblique through holes.

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