An oil supply unit for a high-pressure common rail system

Abstract

The present invention belongs to the technical field of high-pressure oil pumps for internal combustion engines, and specifically discloses an oil supply unit for a common rail system, which includes a guiding piston, a reset member, a plunger, a plunger sleeve, an inlet valve, an outlet valve, an outlet valve seat, an upper outlet valve seat and a mounting seat. Key components such as the plunger, the outlet valve and the guiding piston are cleverly combined together through second threaded connectors, second threaded connectors and retaining rings to assemble an oil supply unit. This oil supply unit can be disassembled and assembled as a whole, and has the advantages of simple and convenient disassembly and assembly. On the one hand, this design greatly reduces the maintenance difficulty of the common rail system and reduces the maintenance time of the oil pump, thereby greatly reducing the maintenance cost and spare part cost of the product. On the other hand, this design can change the high-pressure oil pump fault maintenance to on-site maintenance, that is, replacing the oil supply unit, which can greatly improve the reliability of the oil pump during use, especially the mission reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-pressure fuel pumps for internal combustion engines, and particularly relates to a fuel supply unit for a common rail system. Background Art

[0002] The common rail technology refers to a fuel supply method in a closed-loop system composed of a high-pressure fuel pump, a pressure sensor, and an ECU, in which the generation of injection pressure and the injection process are completely separated from each other. The high-pressure fuel pump delivers high-pressure fuel to the common fuel pipe, and the oil pressure in the common fuel pipe is precisely controlled, so that the pressure of the high-pressure fuel pipe is independent of the engine speed, which can greatly reduce the change of the fuel supply pressure of the diesel engine with the engine speed. Therefore, the defects of the traditional diesel engine are reduced. The ECU controls the fuel injection volume of the injector, and the fuel injection volume depends on the pressure of the fuel rail (common fuel pipe) and the opening time of the solenoid valve.

[0003] The common rail system mainly consists of an electronic control unit, a high-pressure fuel pump, a high-pressure fuel rail and high-pressure fuel pipes, an electronically controlled injector, and various sensors. The low-pressure fuel pump pressurizes the fuel and sends it into the high-pressure fuel rail. The pressure in the high-pressure fuel rail is adjusted by the electronic control unit according to the fuel rail pressure measured by the fuel rail pressure sensor and the requirements. The fuel in the high-pressure fuel rail passes through the high-pressure fuel pipe, and according to the operating state of the machine, the electronic control unit determines the appropriate injection timing from the preset MAP diagram, and the injection duration is controlled by the electro-hydraulic electronically controlled injector to inject the fuel into the cylinder.

[0004] At present, the high-pressure fuel pumps used in the common rail system all adopt the form of a combined pump. A fuel pump assembly contains several sets of plunger pairs, delivery valve pairs, guide piston assemblies and other components inside. When a cylinder jams or fails, due to the complex internal structure of the fuel pump and the complicated installation process, the entire pump is replaced and sent back to the factory for repair, which directly reduces the use reliability of the product and increases the spare parts cost and maintenance cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a fuel supply unit for a common rail system to solve the problems of the complex internal structure of the existing high-pressure fuel pump, the need to replace the entire pump when a failure occurs, resulting in low use reliability and high cost.

[0006] To achieve the above object, the technical solution of the present invention is as follows: An oil supply unit for a high-pressure common rail system, comprising a guiding piston, a reset member, a plunger, a plunger sleeve, an inlet valve, an outlet valve, an outlet valve seat, an upper outlet valve seat and a mounting seat; the mounting seat is detachably connected inside the inner cavity of the guiding piston; a first through hole is provided inside the plunger sleeve, the upper side of the plunger is slidably connected inside the first through hole, and the lower side of the plunger is mounted on the mounting seat; the outlet valve seat is located between the upper outlet valve seat and the plunger sleeve, the outlet valve seat is located on the upper side of the plunger sleeve, and the upper outlet valve seat, the outlet valve seat and the plunger sleeve are detachably connected; the reset member is located between the plunger sleeve and the mounting seat;

[0007] An oil outlet is provided on the upper outlet valve seat, an oil outlet mounting hole communicating with the oil outlet is provided on the upper side of the outlet valve seat, an oil inlet mounting hole communicating with the first through hole is provided on the upper side of the plunger sleeve, a second through hole is provided on the lower side of the outlet valve seat, and the upper and lower sides of the second through hole are respectively communicated with the oil outlet mounting hole and the oil inlet mounting hole; the outlet valve is mounted in the oil outlet mounting hole and can connect or disconnect the oil outlet mounting hole and the second through hole; the inlet valve is mounted in the oil inlet mounting hole, and the upper side of the inlet valve can abut against the bottom of the outlet valve seat; the oil inlet mounting hole includes a vertical groove and a transition groove arranged in sequence from top to bottom, the diameter of the vertical groove is larger than that of the first through hole; both sides of the transition groove are respectively connected to the bottom of the vertical groove and the top of the first through hole, and the transition groove is in a frustum-shaped structure; the bottom of the inlet valve is slidably connected inside the first through hole, the upper part of the inlet valve is slidably connected with the vertical groove, a transition section is provided in the middle of the inlet valve, the outer periphery of the transition section matches the transition groove, and the transition section can abut against the transition groove; an oil inlet ring groove is provided at the bottom of the outlet valve seat, an annular groove corresponding to the oil inlet ring groove is provided at the top of the inlet valve, an oil inlet hole is provided on the inlet valve, and both sides of the oil inlet hole are respectively communicated with the annular groove and the first through hole.

[0008] Furthermore, the plunger includes an upper plunger section and a lower plunger section, the diameter of the lower plunger section is smaller than that of the upper plunger section, a semi-circular ring groove is provided at the lower part of the first through hole, and a retaining ring is mounted in the semi-circular ring groove; the retaining ring can limit the downward movement of the plunger.

[0009] Furthermore, a chamfered band is provided at the top of the lower plunger section, and the retaining ring is used to limit the chamfered band.

[0010] Furthermore, an outlet valve spring is connected between the inner cavity of the outlet valve and the upper outlet valve seat.

[0011] Furthermore, a step hole is provided on the mounting seat, the lower side of the plunger is located in the small hole of the step hole, a boss is fixed to the bottom of the plunger, the diameter of the boss is larger than the diameter of the bottom of the plunger, and the boss is slidably connected in the large hole of the step hole; the bottom of the boss can be against the bottom surface of the inner cavity of the guide piston.

[0012] Furthermore, the reset member includes an outer spring and an inner spring, a large step and a small step are provided in the middle of the plunger, the upper side of the inner spring is against the small step, and the lower side is connected to the mounting seat; the outer spring is located outside the inner spring and the upper side of the outer spring is against the large step, and the lower side is connected to the mounting seat.

[0013] Furthermore, a plurality of first threaded holes are provided at the bottom of the inner cavity of the guide piston, and a third through hole facing the first threaded holes is provided on the mounting seat; and the first threaded connector passes through the third through hole and is threadedly connected to the first threaded hole.

[0014] Furthermore, a plurality of second threaded holes are provided on the top of the plunger sleeve, and a fourth through hole facing the second threaded holes is provided on the oil outlet valve seat and the oil outlet valve upper seat, and the second threaded connecting member passes through the fourth through holes on the oil outlet valve upper seat and the oil outlet valve seat and is threadedly connected with the second threaded holes.

[0015] The working principle of this technical solution is:

[0016] During assembly, the oil inlet valve should be installed in the oil inlet mounting hole of the plunger sleeve first, and the transition section and transition groove of the oil inlet valve should be against each other. Then install the oil outlet valve seat in sequence, and install the oil outlet valve and the oil outlet valve spring in the oil outlet mounting hole of the oil outlet valve seat in sequence, then install the oil outlet valve upper seat on the oil outlet valve seat, and fix the oil outlet valve upper seat and the oil outlet valve seat on the plunger sleeve through the second threaded connector. Pass the plunger through the small hole of the step hole on the mounting seat, and insert the boss at the tail of the plunger into the large hole of the mounting seat, install the mounting seat in the inner cavity of the guide piston, make the bottom of the boss contact with the bottom surface of the inner cavity of the guide piston, and fix the mounting seat in the inner cavity of the guide piston through the first threaded connector. Then install the inner spring and the outer spring on the mounting seat in sequence, and slowly install the plunger into the first through hole of the plunger sleeve, ensuring that the upper ends of the inner spring and the outer spring contact with the small step and the large step on the plunger sleeve in sequence. Then press the plunger in with force to move it upward. When the rounded band on the plunger passes through the semicircular groove in the plunger sleeve and is stuck in the retaining ring, it is slowly released. The plunger slowly descends under the action of the spring force (inner spring and outer spring) until the rounded band on the plunger is stuck in the retaining ring. At this point, the oil supply unit is installed.

[0017] During operation, when the plunger moves downward, the pressure in the plunger chamber decreases. The inlet valve moves downward under the action of its own weight and the inlet pressure. The transition section of the inlet valve abuts against the transition groove of the plunger sleeve and seals the low pressure. When the plunger moves upward, the pressure in the plunger chamber increases. The lower end face of the inlet valve is impacted by the high pressure and overcomes its own weight to move upward. The top of the inlet valve contacts the bottom of the outlet valve seat and seals the high pressure.

[0018] During replacement, the rectification unit can be directly taken out from the high-pressure oil pump of the common rail system, and a new unit can be replaced to complete the repair and replacement work, greatly simplifying the repair work of the high-pressure oil pump, saving repair time and reducing repair costs.

[0019] The beneficial effects of this technical solution are as follows:

[0020] (1) In this solution, key components such as the plunger, outlet valve, and guide piston are cleverly combined together through the second threaded connector, the second threaded connector, and the retaining ring to form a fuel supply unit. This fuel supply unit can be disassembled and assembled as a whole, and has the advantages of simple and convenient disassembly and assembly. On the one hand, this design greatly reduces the maintenance difficulty of the high-pressure common rail system, reduces the maintenance time of the oil pump, thereby greatly reducing the maintenance cost and spare parts cost of the product. On the other hand, this design can adjust the high-pressure oil pump fault repair to on-site repair, that is, replace the fuel supply unit, which can greatly improve the reliability of the oil pump, especially the mission reliability.

[0021] (2) The inlet valve adopts a springless structure form and realizes the sealing of low pressure through the transition section, ensuring that the use reliability and life of the product are greatly improved without affecting the functional performance.

[0022] (3) The fuel supply unit is connected and fixed through a structure that can be repeatedly disassembled by the first threaded connector, the second threaded connector, and the retaining ring. While improving the maintainability of the high-pressure oil pump, it also ensures that the maintainability of the fuel supply unit is not affected. Description of the Drawings

[0023] Figure 1 It is a schematic structural diagram of a fuel supply unit for a high-pressure common rail system of the present invention;

[0024] Figure 2 It is Figure 1 an enlarged view of part A in

[0025] Figure 3 It is Figure 1 an enlarged view of part B in

[0026] Figure 4 It is Figure 1 a schematic structural diagram of the connection between the guide piston and the mounting seat in Detailed Embodiments

[0027] The following will be further described in detail through specific embodiments:

[0028] The reference numerals in the accompanying drawings of the specification include: guiding piston 1, plunger 2, plunger sleeve 3, fuel injection valve seat 4, upper fuel injection valve seat 5, mounting seat 6, first through hole 7, upper plunger section 8, lower plunger section 9, outer spring 10, inner spring 11, fuel injection valve 12, fuel injection valve spring 13, fuel outlet 14, second through hole 15, inlet valve 16, second threaded connector 17, first threaded connector 18, boss 19, inlet ring groove 20, annular groove 21, vertical groove 22, transition groove 23, fuel outlet mounting hole 24, fuel inlet mounting hole 25, retaining ring 26, semi-circular ring groove 27, chamfered zone 28, stepped hole 29, positioning surface 30, large step 31, small step 32.

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] The embodiment is basically as shown in the attached Figures 1-4 figures: A fuel supply unit for a high-pressure common rail system, as Figure 1 shown, includes a guiding piston 1, a reset member, a plunger 2, a plunger sleeve 3, an inlet valve 16, a fuel injection valve 12, a fuel injection valve seat 4, an upper fuel injection valve seat 5 and a mounting seat 6; the mounting seat 6 is detachably connected inside the inner cavity of the guiding piston 1. Specifically, a plurality of first threaded holes are uniformly provided at the bottom of the inner cavity of the guiding piston 1, and a third through hole is provided on the mounting seat 6 opposite to the first threaded holes; the first threaded connector 18 passes through the third through hole and is threadedly connected to the first threaded hole.

[0031] As Figure 3 shown, a first through hole 7 is provided inside the plunger sleeve 3, a semi-circular ring groove 27 is provided at the lower part of the first through hole 7, and a retaining ring 26 (specifically a wire retaining ring 26) is installed in the semi-circular ring groove 27, and the retaining ring 26 can limit the downward movement of the plunger 2. As Figure 1 shown, the plunger 2 includes an upper plunger section 8 and a lower plunger section 9, and the diameter of the lower plunger section 9 is smaller than that of the upper plunger section 8. The upper plunger section 8 is slidably connected inside the first through hole 7, and the lower side of the lower plunger section 9 is installed on the mounting seat 6; as Figure 4As shown, specifically, the mounting seat 6 is provided with a stepped hole 29. The lower side of the lower plunger section 9 is located in the small hole of the stepped hole 29, and the diameter of the small hole is larger than the diameter of the upper plunger section 8. A boss 19 is fixed to the bottom of the lower plunger section 9. The diameter of the boss 19 is larger than the diameter of the lower plunger section 9, and the upper part of the boss 19 is slidably connected in the large hole of the stepped hole 29. The bottom of the inner cavity of the guide piston 1 is provided with a positioning surface 30, and the bottom of the boss 19 can abut against the positioning surface 30 at the bottom of the inner cavity of the guide piston 1. As Figure 3 shown, a chamfered band 28 is provided at the top of the lower plunger section 9, and the retaining ring 26 is used to limit the chamfered band 28.

[0032] As Figure 1 shown, the fuel outlet valve seat 4 is located between the upper fuel outlet valve seat 5 and the plunger sleeve 3. The fuel outlet valve seat 4 is located above the plunger sleeve 3, and the upper fuel outlet valve seat 5, the fuel outlet valve seat 4 and the plunger sleeve 3 are detachably connected. Specifically, a plurality of second threaded holes are evenly provided at the top of the plunger sleeve 3. Fourth through holes are provided on both the fuel outlet valve seat 4 and the upper fuel outlet valve seat 5 and are aligned with the second threaded holes. The second threaded connector 17 passes through the fourth through holes on the upper fuel outlet valve seat 5 and the fuel outlet valve seat 4 and is threadedly connected to the second threaded holes.

[0033] The first threaded connector 18 and the second threaded connector 17 can be connectors such as bolts and screws.

[0034] The reset member is located between the plunger sleeve 3 and the mounting seat 6. Specifically, the reset member includes an outer spring 10 and an inner spring 11. A large step 31 and a small step 32 are provided in the middle of the plunger 2. The upper side of the inner spring 11 abuts against the small step 32, and the lower side is connected to the mounting seat 6. The outer spring 10 is located outside the inner spring 11, and the upper side of the outer spring 10 abuts against the large step 31, and the lower side is connected to the mounting seat 6.

[0035] As Figure 1 、 2As shown, the oil outlet valve upper seat 5 is provided with an oil outlet port 14, the upper side of the oil outlet valve seat 4 is provided with an oil outlet mounting hole 24 connected to the oil outlet port 14, the upper side of the plunger sleeve 3 is provided with an oil inlet mounting hole 25 connected to the first through hole 7, and the lower side of the oil outlet valve seat 4 is provided with a second through hole 15, and the upper and lower sides of the second through hole 15 are respectively connected to the oil outlet mounting hole 24 and the oil inlet mounting hole 25. The oil outlet valve 12 is installed in the oil outlet mounting hole 24 and can connect or isolate the oil outlet mounting hole 24 and the second through hole 15, and the oil outlet valve spring 13 is connected between the inner cavity of the oil outlet valve 12 and the oil outlet valve upper seat 5. The oil inlet valve 16 is installed in the oil inlet mounting hole 25, and the upper side of the oil inlet valve 16 can be against the bottom of the oil outlet valve seat 4. The oil inlet mounting hole 25 includes a vertical groove 22 and a transition groove 23 arranged in sequence from top to bottom. The diameter of the vertical groove 22 is larger than the first through hole 7. The two sides of the transition groove 23 are respectively connected to the bottom of the vertical groove 22 and the top of the first through hole 7. The transition groove 23 is a truncated cone structure. The bottom of the oil inlet valve 16 is slidably connected to the first through hole 7. The upper part of the oil inlet valve 16 is slidably connected to the vertical groove 22. The middle part of the oil inlet valve 16 is provided with a transition section. The outer periphery of the transition section matches the transition groove 23, and the transition section can be abutted against the transition groove 23. The bottom of the oil outlet valve seat 4 is provided with an oil inlet annular groove 20. The top of the oil inlet valve 16 is provided with an annular groove 21 corresponding to the oil inlet annular groove 20. The oil inlet valve 16 is provided with an oil inlet hole. The upper and lower sides of the oil inlet hole are respectively connected to the annular groove 21 and the first through hole 7.

[0036] The specific implementation process is as follows:

[0037] During assembly, the oil inlet valve 16 is preferably installed in the oil inlet mounting hole 25 of the plunger sleeve 3, and the transition section of the oil inlet valve 16 and the transition groove 23 are abutted. Then the oil outlet valve seat 4 is installed, and the oil outlet valve 12 and the oil outlet valve spring 13 are sequentially installed in the oil outlet mounting hole 24 of the oil outlet valve seat 4. Then the oil outlet valve upper seat 5 is installed on the oil outlet valve seat 4, and the oil outlet valve upper seat 5 and the oil outlet valve seat 4 are fixed to the plunger sleeve 3 through the second threaded connector 17. The plunger 2 is passed through the small hole of the step hole 29 on the mounting seat 6, and the boss 19 at the tail of the plunger 2 is inserted into the large hole of the mounting seat 6. The mounting seat 6 is installed in the inner cavity of the guide piston 1, so that the bottom of the boss 19 contacts the positioning surface 30 at the bottom of the inner cavity of the guide piston 1, and the mounting seat 6 is fixed to the inner cavity of the guide piston 1 through the first threaded connector 18. Then, the inner spring 11 and the outer spring 10 are sequentially installed on the mounting seat 6, and the plunger 2 is slowly installed into the first through hole 7 of the plunger sleeve 3, ensuring that the upper ends of the inner spring 11 and the outer spring 10 are sequentially in contact with the small step and the large step on the plunger sleeve 3. Then, the plunger 2 is pressed in forcefully to make the plunger 2 move upward. When the rounded band 28 on the plunger 2 passes through the semicircular ring groove 27 in the plunger sleeve 3, it is clamped into the retaining ring 26 and then slowly released. The plunger 2 slowly moves downward under the action of the spring force (inner spring 11 and outer spring 10) until the rounded band 28 on the plunger 2 is clamped at the retaining ring 26. At this point, the installation of the oil supply unit is completed.

[0038] During operation, when the plunger 2 moves downward, the pressure in the plunger 2 chamber decreases. The inlet valve 16 moves downward under the action of its own weight and the inlet pressure. The transition section of the inlet valve 16 abuts against the transition groove 23 of the plunger sleeve 3 and seals the low pressure. When the plunger 2 moves upward, the pressure in the plunger 2 chamber increases. The lower end face of the inlet valve 16 is impacted by the high pressure and moves upward against its own weight. The top of the inlet valve 16 contacts the bottom of the outlet valve seat 4 and seals the high pressure.

[0039] During replacement, the rectification unit can be directly taken out from the high-pressure oil pump of the common rail system, and a new unit can be replaced to complete the repair and replacement work, greatly simplifying the repair work of the high-pressure oil pump, saving repair time and reducing repair costs.

[0040] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device.

[0041] The above are only embodiments of the present invention. Specific structures and common knowledge such as characteristics that are well known in the art are not described in detail here. Those of ordinary skill in the art know all the common general technical knowledge in the technical field to which the invention belongs before the filing date or the priority date, can know all the prior art in this field, and have the ability to apply conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to improve and implement this solution. Some typical well-known structures or well-known methods should not become obstacles for those of ordinary skill in the art to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. An oil supply unit for a high-pressure common rail system, characterized in that: it includes a guiding piston (1), a reset member, a plunger (2), a plunger sleeve (3), an inlet valve (16), an outlet valve (12), an outlet valve seat (4), an upper outlet valve seat (5) and a mounting seat (6); the mounting seat (6) is detachably connected inside the inner cavity of the guiding piston (1); a first through hole (7) is provided inside the plunger sleeve (3), the upper side of the plunger (2) is slidably connected inside the first through hole (7), and the lower side of the plunger (2) is mounted on the mounting seat (6); the outlet valve seat (4) is located between the upper outlet valve seat (5) and the plunger sleeve (3), the outlet valve seat (4) is located on the upper side of the plunger sleeve (3), and the upper outlet valve seat (5), the outlet valve seat (4) and the plunger sleeve (3) are detachably connected; the reset member is located between the plunger sleeve (3) and the mounting seat (6); a plurality of first threaded holes are provided at the bottom of the inner cavity of the guiding piston (1), and a third through hole is provided on the mounting seat (6) opposite to the first threaded holes; a first threaded connector (18) passes through the third through hole and is threadedly connected to the first threaded hole; the plunger (2) includes an upper plunger section (8) and a lower plunger section (9), the diameter of the lower plunger section (9) is smaller than that of the upper plunger section (8), a semi-circular ring groove (27) is provided at the lower part of the first through hole (7), and a retaining ring (26) is installed in the semi-circular ring groove (27); the retaining ring (26) can limit the downward movement of the plunger (2); a plurality of second threaded holes are provided at the top of the plunger sleeve (3), and fourth through holes are provided on both the outlet valve seat (4) and the upper outlet valve seat (5) opposite to the second threaded holes, and a second threaded connector (17) passes through the fourth through holes on the upper outlet valve seat (5) and the outlet valve seat (4) and is threadedly connected to the second threaded hole; An oil outlet (14) is provided on the upper seat (5) of the fuel injection valve. An oil outlet mounting hole (24) communicating with the oil outlet (14) is provided on the upper side of the fuel injection valve seat (4). An oil inlet mounting hole (25) communicating with the first through hole (7) is provided on the upper side of the plunger sleeve (3). A second through hole (15) is provided on the lower side of the fuel injection valve seat (4). The upper and lower sides of the second through hole (15) are respectively communicated with the oil outlet mounting hole (24) and the oil inlet mounting hole (25). The fuel injection valve (12) is installed in the oil outlet mounting hole (24) and can connect or disconnect the oil outlet mounting hole (24) and the second through hole (15). The oil inlet valve (16) is installed in the oil inlet mounting hole (25), and the upper side of the oil inlet valve (16) can abut against the bottom of the fuel injection valve seat (4). The oil inlet mounting hole (25) includes a vertical groove (22) and a transition groove (23) arranged in sequence from top to bottom. The diameter of the vertical groove (22) is larger than that of the first through hole (7). The two sides of the transition groove (23) are respectively connected with the bottom of the vertical groove (22) and the top of the first through hole (7). The transition groove (23) is in a frustum-shaped structure. The bottom of the oil inlet valve (16) is slidably connected in the first through hole (7), the upper part of the oil inlet valve (16) is slidably connected with the vertical groove (22), a transition section is provided in the middle of the oil inlet valve (16), the outer periphery of the transition section matches the transition groove (23), and the transition section can abut against the transition groove (23). An oil inlet ring groove (20) is provided at the bottom of the fuel injection valve seat (4). An annular groove (21) corresponding to the oil inlet ring groove (20) is provided at the top of the oil inlet valve (16). An oil inlet hole is provided on the oil inlet valve (16), and the two sides of the oil inlet hole are respectively communicated with the annular groove (21) and the first through hole (7).

2. The fuel supply unit for a high-pressure common rail system according to claim 1, characterized in that: A chamfered band (28) is provided at the top of the lower plunger section (9), and the retaining ring (26) is used to limit the chamfered band (28).

3. The fuel supply unit for a high-pressure common rail system according to claim 1, characterized in that: An oil injection valve spring (13) is connected between the inner cavity of the fuel injection valve (12) and the upper seat (5) of the fuel injection valve.

4. The fuel supply unit for a high-pressure common rail system according to claim 1, characterized in that: A stepped hole (29) is provided on the mounting seat (6). The lower side of the plunger (2) is located in the small hole of the stepped hole (29). A boss (19) is fixed at the bottom of the plunger (2). The diameter of the boss (19) is larger than the diameter of the bottom of the plunger (2). The boss (19) is slidably connected in the large hole of the stepped hole (29). The bottom of the boss (19) can abut against the inner cavity bottom surface of the guide piston (1).

5. The fuel supply unit for a high-pressure common rail system according to claim 1, characterized in that: The reset member includes an outer spring (10) and an inner spring (11). A large step (31) and a small step (32) are provided in the middle of the plunger (2). The upper side of the inner spring (11) abuts against the small step (32), and the lower side is connected to the mounting seat (6); the outer spring (10) is located outside the inner spring (11), and the upper side of the outer spring (10) abuts against the large step (31), and the lower side is connected to the mounting seat (6).

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