Common rail fuel oil low-pressure loop system

Abstract

A common-rail fuel oil low-pressure loop system belongs to the technical field of non-road diesel engines and comprises an oil injector oil return part, a common-rail pipe oil return part, a high-pressure oil pump oil return part, a space integration part and a total oil return part. The oil injector oil return part, the common rail pipe oil return part and the high-pressure oil pump oil return part are converged into one position in the space integration part, and fuel oil is introduced into an oil tank through the main oil return part. The beneficial effects of the utility model are that: by adopting the design mode that branches converge and lead out, the oil return of the oil injector, the oil return of the common rail pipe, the oil return of the high-pressure oil pump, the space integration and the total oil return are reasonably arranged, and the purposes of compact structure, low cost and reliable performance are realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of non-road diesel engines, relates to a high-pressure common rail fuel system, and specifically relates to a common rail fuel low-pressure circuit system. Background Art

[0002] At present, in order to meet the non-road National VI emission technology requirements and make appropriate technical reserves for subsequent emission upgrades, improving fuel injection pressure and charging efficiency has become the mainstream technical direction for optimizing combustion, reducing emissions and improving fuel economy.

[0003] In this context, high-pressure common rail and four-valve valves have become a necessary configuration. At the same time, it is necessary to select appropriate key components such as high-pressure oil pumps, common rail pipes, and injectors. The low-pressure fuel circuit system must also be newly designed and developed. Most of the current non-road National VI diesel engines are gradually upgraded and modified based on the prototypes developed many years ago. This has resulted in the diesel engine body having a cramped space and limited structure, and there are problems such as difficulty in improvement, insufficient space, and high technical difficulty.

[0004] For non-road four-valve common rail diesel engines that use high-pressure connecting rods, the oil return channel of the injector is usually arranged inside the cylinder head, which poses great difficulties in the design of the low-pressure fuel circuit system. It is difficult to take into account various indicators such as reasonable layout, compact structure, low cost, and reliable performance. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of the utility model is to propose a common rail fuel low-pressure circuit system to address the difficulties in designing the fuel low-pressure circuit system mentioned in the background technology, and the difficulty in taking into account various indicators such as reasonable layout, compact structure, low cost, and reliable performance.

[0006] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a common rail fuel low-pressure circuit system, including a cylinder head, an injector, an intake pipe, a high-pressure fuel rail, a high-pressure fuel pump, an injector oil return part, a common rail pipe oil return part, a high-pressure fuel pump oil return part, a space integration part and a total oil return part, the front end of the cylinder head is connected with an intake pipe, the intake pipe is provided with a high-pressure fuel rail, a plurality of injectors are arranged at intervals on the upper part of the cylinder head, the plurality of injectors are connected with the injector oil return passage arranged on the cylinder head, the end of the injector oil return passage is connected with one end of the injector oil return part, the other end of the injector oil return part is connected with the space integration part, the injector The devices are all connected with a high-pressure connecting rod, which is connected to the high-pressure oil rail through the high-pressure oil pipe behind the rail, the high-pressure oil rail is connected to one end of the oil return part of the common rail pipe, and the other end of the oil return part of the common rail pipe is connected to the space integration part, the space integration part is installed on the intake pipe, the space integration part is connected to one end of the oil return part of the high-pressure oil pump, and the other end of the oil return part of the high-pressure oil pump is connected to the high-pressure oil pump, the high-pressure oil pump is provided with a high-pressure oil pipe in front of the rail, and the other end of the high-pressure oil pipe in front of the rail is connected to the high-pressure oil rail, the space integration part is also connected to one end of the total oil return part, and the other end of the total oil return part is connected to the oil tank.

[0007] The injector oil return part includes a connecting block component and an oil return pipe component. The connecting block component is connected to the injector oil return passage of the cylinder head. The connecting block component is connected to one end of the oil return pipe component, and the other end of the oil return pipe component is connected to the space integration part.

[0008] The connecting block component includes an oil return connecting block, fixing bolts and an O-ring. The oil return connecting block is provided with a connecting block oil inlet and a connecting block oil outlet. The connecting block oil inlet and the connecting block oil outlet are connected inside the oil return connecting block to form an L-shaped oil passage. An annular sealing groove and a sealing flange surface are provided at the connecting block oil inlet of the oil return connecting block. The annular sealing groove cooperates with the O-ring for sealing. The sealing flange surface is provided with a threaded through hole A and the oil return connecting block is installed on the end of the injector oil return passage on the side of the cylinder head by fixing bolts. The connecting block oil outlet is provided with an internal thread and is connected to the oil return pipe component through it.

[0009] The oil return pipe component includes an articulated bolt and an injector oil return pipe, a columnar oil passage is arranged inside the articulated bolt, a two-way oil port A and a two-way oil port B are arranged inside the columnar oil passage, and the two-way oil port A and the two-way oil port B are designed to be staggered; one-way oil ball heads are arranged at both ends of the injector oil return pipe, the one-way oil ball head at one end of the injector oil return pipe is connected with the internal thread of the oil outlet of the connecting block through a articulated bolt, and the one-way oil ball head at the other end of the injector oil return pipe is connected with the space integration part through a articulated bolt.

[0010] The oil return part of the common rail pipe includes a hinge bolt and a common rail oil return pipe. One-way oil passing ball heads are arranged at both ends of the common rail oil return pipe. The one-way oil passing ball head at one end of the common rail oil return pipe is connected to the high-pressure oil rail through a hinge bolt, and the one-way oil passing ball head at the other end of the common rail oil return pipe is connected to the space integration part through a hinge bolt.

[0011] The oil return part of the high-pressure oil pump includes a hinge bolt, an oil transfer pump oil return pipe, a two-way oil passing ball head, and a plunger oil return pipe. One end of the oil transfer pump oil return pipe and one end of the plunger oil return pipe are connected through a two-way oil passing ball head. A one-way oil passing ball head is arranged at the other end of the oil transfer pump oil return pipe and is connected to the space integration part through its cooperation with the hinge bolt. A one-way oil passing ball head is arranged at the other end of the plunger oil return pipe and is connected to the high-pressure oil pump through its cooperation with the hinge bolt.

[0012] The space integration part includes an oil return integration block and a fixing bolt. The oil return integration block is provided with a blind hole oil passage. An oil inlet for the oil return part of the common rail pipe, an oil inlet for the oil return part of the injector, an oil outlet for the total oil return part, and an oil inlet for the oil return part of the high-pressure oil pump are arranged on the blind hole oil passage. Internal threads are provided at the above-mentioned oil inlets and outlets. Threaded through holes B for cooperating with the fixing bolts are arranged on the oil return integration block.

[0013] The total oil return part includes a conversion joint, a bent oil return steel pipe, an oil return rubber pipe, and a total oil return joint. The cross-section of the conversion joint is in a "middle" shape structure. The conversion joint is provided with a central through hole vertically penetrating. A sealing conical surface is arranged at the mouth of the central through hole. External threads are arranged on the outer wall of the central through hole. A sealing spherical surface is arranged at one end of the bent oil return steel pipe. The sealing spherical surface cooperates with the sealing conical surface of the conversion joint. A locking nut is sleeved on the pipe body of the bent oil return steel pipe. The internal threads of the locking nut cooperate with the external threads of the conversion joint. The other end of the bent oil return steel pipe is connected to one end of the oil return rubber pipe. The other end of the oil return rubber pipe is connected with a total oil return joint, and the total oil return joint is connected to the fuel tank.

[0014] Combined sealing washers are arranged at the connection parts of the hinge bolts and the one-way oil passing ball heads.

[0015] The beneficial effects of the present utility model are as follows: By adopting the design method of branch merging and leading out, the present utility model reasonably arranges the five parts of the oil return of the injector, the oil return of the common rail pipe, the oil return of the high-pressure oil pump, space integration, and total oil return, achieving the goals of compact structure, low cost, and reliable performance. Brief Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of the low-pressure circuit system of the present utility model.

[0017] Figure 2 This is a schematic diagram of the utility model installed on a complete machine.

[0018] Figure 3 This is a schematic diagram of the structure of the oil return part of the fuel injector of the utility model.

[0019] Figure 4 This is a schematic diagram of the structure of the oil return connection block of the utility model.

[0020] Figure 5 It is a side sectional schematic diagram of the oil return connection block of the utility model.

[0021] Figure 6 It is a schematic cross-sectional view of the hinge bolt structure of the utility model.

[0022] Figure 7 This is a schematic diagram of the structure of the oil return part of the common rail pipe of the utility model.

[0023] Figure 8 This is a schematic diagram of the structure of the oil return part of the high-pressure oil pump of the utility model.

[0024] Fig. 9 It is a schematic diagram of the structure of the space integration part of the utility model.

[0025] Fig.10 It is a cross-sectional schematic diagram of the space integration part of the utility model.

[0026] Fig.11 It is a schematic diagram of the structure of the total oil return part of the utility model.

[0027] Fig.12 It is a cross-sectional schematic diagram of the conversion joint of the utility model.

[0028] In the figure: 1. Injector oil return part, 101. Oil return connection block, 1011. Connection block oil inlet, 1012. Connection block oil outlet, 1013. L-shaped oil channel, 1014. Annular sealing groove, 1015. Sealing flange surface, 1016. Threaded through hole A, 102. O-ring, 103. Injector oil return pipe, 2. Common rail oil return part, 201. Common rail oil return pipe, 3. High-pressure oil pump oil return part, 301 Oil pump oil return pipe, 302. Two-way oil ball head, 303. Plunger oil return pipe, 4. Space integration part, 401. Oil return integrated block, 4011. Blind hole oil channel, 4012. Common rail oil return part oil inlet, 4013. Injector oil return part oil inlet, 4014. Total oil return part oil outlet, 4015 , oil inlet of the return oil part of the high-pressure oil pump, 4016, threaded through hole B, 5, total oil return part, 501, conversion joint, 5011, center through hole, 5012, sealing cone, 502, bent oil return steel pipe, 5021, sealing spherical surface, 5022, locking nut, 503, return oil rubber tube, 504, total oil return joint, 6, cylinder head, 7, injector, 701, high-pressure connecting rod, 8, intake pipe, 9, high-pressure oil rail, 10, high-pressure oil pump, 11, injector oil return channel, 12, high-pressure oil pipe behind the rail, 13, high-pressure oil pipe in front of the rail, 14, hinged bolt, 1401, columnar oil channel, 1402, two-way oil port A, 1403, two-way oil port B, 15, one-way oil ball head, 16, combined sealing gasket, 17, fixing bolt. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings of this specification to clearly and completely describe the technical solution of the utility model. It should be noted that the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] See also Figure 1-Figure 12A common rail fuel low-pressure circuit system includes a cylinder head 6, an injector 7, an intake pipe 8, a high-pressure fuel rail 9, a high-pressure fuel pump 10, an injector oil return part 1, a common rail pipe oil return part 2, a high-pressure fuel pump oil return part 3, a space integration part 4 and a total oil return part 5. The front end of the cylinder head 6 is connected with an intake pipe 8, and the intake pipe 8 is provided with a high-pressure fuel rail 9. A plurality of injectors 7 are arranged at intervals on the upper part of the cylinder head 6. The plurality of injectors 7 are connected to an injector oil return passage 11 arranged on the cylinder head 1. The end of the injector oil return passage 11 is connected to one end of the injector oil return part 1, and the other end of the injector oil return part 1 is connected to the space integration part 4. The injectors 7 are all connected with a high-pressure connecting rod 70 1, the high-pressure connecting rod 701 is connected to the high-pressure oil rail 9 through the high-pressure oil pipe 12 behind the rail, the high-pressure oil rail 9 is connected to one end of the common rail pipe return oil part 2, the other end of the common rail pipe return oil part 2 is connected to the space integration part 4, the space integration part 4 is installed on the intake pipe 8, the space integration part 4 is connected to one end of the high-pressure oil pump return oil part 2, the other end of the high-pressure oil pump return oil part 2 is connected to the high-pressure oil pump 10, the high-pressure oil pump 10 is provided with a high-pressure oil pipe 13 in front of the rail, the other end of the high-pressure oil pipe 13 in front of the rail is connected to the high-pressure oil rail 9, the space integration part 4 is also connected to one end of the total oil return part 5, the other end of the total oil return part 5 is connected to the oil tank. The injector oil return part 1 includes a connecting block component and an oil return pipe component, the connecting block component is connected to the injector oil return passage 11 of the cylinder head 6, the connecting block component is connected to one end of the oil return pipe component, and the other end of the oil return pipe component is connected to the space integration part 4. The connecting block component includes an oil return connecting block 101, a fixing bolt 17 and an O-ring 102. The oil return connecting block 101 is provided with a connecting block oil inlet 1011 and a connecting block oil outlet 1012. The connecting block oil inlet 1011 and the connecting block oil outlet 1012 are connected inside the oil return connecting block 101 to form an L-shaped oil passage 1013. The connecting block oil inlet 1011 of the oil return connecting block 101 is provided with an annular sealing groove 1014 and a sealing flange surface 1015. The annular sealing groove 1014 cooperates with the O-ring 102 for sealing. The sealing flange surface 1015 is provided with a threaded through hole A1016 and the oil return connecting block 101 is installed on the end of the injector oil return passage 11 on the side of the cylinder head 6 by the fixing bolt 17. The connecting block oil outlet 1012 is provided with an internal thread and is connected to the oil return pipe component through it.The oil return pipe component includes an articulated bolt 14 and an injector oil return pipe 103, wherein a columnar oil passage 1401 is arranged inside the articulated bolt 14, and a two-way oil port A1402 and a two-way oil port B1403 are arranged inside the columnar oil passage 1401, and the two-way oil port A1402 and the two-way oil port B1403 are designed to be staggered; one-way oil ball heads 15 are arranged at both ends of the injector oil return pipe 103, and the one-way oil ball head 15 at one end of the injector oil return pipe 103 is connected with the internal thread of the connecting block oil outlet 1012 through the articulated bolt 14, and the one-way oil ball head 15 at the other end of the injector oil return pipe 103 is connected with the space integration part 4 through the articulated bolt 14. The common rail oil return part 2 includes a hinge bolt 14 and a common rail oil return pipe 201. One-way oil ball heads 15 are provided at both ends of the common rail oil return pipe 201. The one-way oil ball head 15 at one end of the common rail oil return pipe 201 is connected to the high-pressure oil rail 9 through the hinge bolt 14, and the one-way oil ball head 15 at the other end of the common rail oil return pipe 201 is connected to the space integration part 4 through the hinge bolt 14. The high-pressure oil pump return oil part 3 includes a hinge bolt 14, an oil pump return oil pipe 301, a two-way oil ball head 302 and a plunger return oil pipe 303. One end of the oil pump return oil pipe 301 and one end of the plunger return oil pipe 303 are connected through the two-way oil ball head 302. The other end of the oil pump return oil pipe 301 is provided with a one-way oil ball head 15, and is connected to the spatial integration part 4 through its cooperation with the hinge bolt 14. The other end of the plunger return oil pipe 303 is provided with a one-way oil ball head 15, and is connected to the high-pressure oil pump 10 through its cooperation with the hinge bolt 14. The spatial integrated part 4 includes an oil return integrated block 401 and a fixing bolt 17. The oil return integrated block 401 is provided with a blind hole oil passage 4011. The blind hole oil passage 4011 is provided with a common rail pipe oil return part oil inlet 4012, an injector oil return part oil inlet 4013, a total oil return part oil outlet 4014 and a high-pressure oil pump oil return part oil inlet 4015. The above-mentioned oil inlets and outlets are all provided with internal threads. The oil return integrated block 401 is provided with a threaded through hole B4016 for cooperating with the fixing bolt 17.The total oil return part 5 includes a conversion joint 501, a bent oil return steel pipe 502, an oil return rubber pipe 503 and a total oil return joint 504. The cross section of the conversion joint 501 is a "Z"-shaped structure. The conversion joint 501 is provided with a central through hole 5011 running vertically, a sealing cone surface 5012 is provided at the mouth of the central through hole 5011, and an external thread is provided on the outer wall of the central through hole 5011. One end of the bent oil return steel pipe 502 is provided with a sealing spherical surface 5021. The sealing The sealing spherical surface 5021 matches with the sealing conical surface 5012 of the conversion joint 501. The body of the bent oil return steel pipe 502 is sleeved with a locking nut 5022. The inner thread of the locking nut 5022 matches with the outer thread of the conversion joint 501. The other end of the bent oil return steel pipe 502 is connected to one end of the oil return rubber pipe 503. The other end of the oil return rubber pipe 503 is connected to the total oil return joint 504. The total oil return joint 504 is connected to the oil tank. The joints of the hinge bolt 14 and the one-way oil ball head 15 are both provided with a combined sealing gasket 16.

[0031] When the utility model is in use:

[0032] The high-pressure oil pump 10 starts to work and pumps oil from the fuel tank, and delivers the fuel to the high-pressure oil rail 9 through the front high-pressure oil pipe 13, and then supplies oil to the high-pressure connecting rod 701 through the rear high-pressure oil pipe 12. In this process, each injector 7 starts to work and sprays fuel, and the excess fuel flows back to the return oil connection block 101 through the injector return oil channel 11, and enters the return oil integrated block 401 through the injector return oil pipe 103. At the same time, the return oil of the high-pressure oil rail 9 also enters the return oil integrated block 401 through the common rail return oil pipe 201. The return oil of the plunger on the oil pressure pump 10 passes through the plunger return oil pipe 303 and the two-way oil ball head 302, merges with the return oil of the oil pump, and flows through the oil pump return oil pipe 301, and finally enters the return oil integrated block 401; at this point, all the branch return oil passes through the common rail pipe return oil part oil inlet 4012, the injector return oil part oil inlet 4013, and the high-pressure oil pump return oil part oil inlet 4015, and is merged and gathered into the blind hole oil channel 4011, and enters the total return oil part 5 through the total return oil part oil outlet 4014, and is finally introduced into the oil tank.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0034] The parts not described in detail in this utility model are prior art.

Claims

1. A common rail fuel low-pressure circuit system, comprising a cylinder head (6), a fuel injector (7), an intake pipe (8), a high-pressure fuel rail (9), a high-pressure fuel pump (10), a fuel injector oil return portion (1), a common rail pipe oil return portion (2), a high-pressure fuel pump oil return portion (3), a space integration portion (4) and a total oil return portion (5), wherein: The front end of the cylinder head (6) is connected to an intake pipe (8), and a high-pressure oil rail (9) is provided on the intake pipe (8). A plurality of fuel injectors (7) are provided at intervals on the upper part of the cylinder head (6), and the plurality of fuel injectors (7) are connected to a fuel injector oil return passage (11) provided on the cylinder head (6). The end of the fuel injector oil return passage (11) is connected to one end of a fuel injector oil return portion (1), and the other end of the fuel injector oil return portion (1) is connected to the space integration portion (4). The fuel injectors (7) are all connected to a high-pressure connecting rod (701), and the high-pressure connecting rod (701) is connected to the high-pressure oil rail (9) through a high-pressure oil pipe (12) behind the rail. The high-pressure oil rail (9) One end of the common rail pipe oil return portion (2) is connected, the other end of the common rail pipe oil return portion (2) is connected to the space integration portion (4), the space integration portion (4) is installed on the intake pipe (8), the space integration portion (4) is connected to one end of the high-pressure oil pump oil return portion (3), the other end of the high-pressure oil pump oil return portion (3) is connected to the high-pressure oil pump (10), the high-pressure oil pump (10) is provided with a front rail high-pressure oil pipe (13), the other end of the front rail high-pressure oil pipe (13) is connected to the high-pressure oil rail (9), the space integration portion (4) is also connected to one end of the total oil return portion (5), the other end of the total oil return portion (5) is connected to the oil tank.

2. A common rail fuel low pressure circuit system according to claim 1, characterized in that: The injector oil return part (1) comprises a connecting block component and an oil return pipe component, wherein the connecting block component is connected to the injector oil return passage (11) of the cylinder head (6), the connecting block component is connected to one end of the oil return pipe component, and the other end of the oil return pipe component is connected to the space integration part (4).

3. A common rail fuel low pressure circuit system according to claim 2, characterized in that: The connecting block component comprises an oil return connecting block (101), a fixing bolt (17) and an O-ring (102); the oil return connecting block (101) is provided with a connecting block oil inlet (1011) and a connecting block oil outlet (1012); the connecting block oil inlet (1011) and the connecting block oil outlet (1012) are connected inside the oil return connecting block (101) to form an L-shaped oil passage (1013); An annular sealing groove (1014) and a sealing flange surface (1015) are provided. The annular sealing groove (1014) cooperates with an O-ring (102) for sealing. The sealing flange surface (1015) is provided with a threaded through hole and the return oil connection block (101) is mounted on the end of the injector return oil passage (11) on the side of the cylinder head (6) via a fixing bolt (17). The connection block oil outlet (1012) is provided with an internal thread and is connected to the return oil pipe component via the internal thread.

4. A common rail fuel low pressure circuit system according to claim 2, characterized in that: The oil return pipe component comprises a hinge bolt (14) and an injector oil return pipe (103); a columnar oil passage (1401) is arranged inside the hinge bolt (14); a two-way oil port A (1402) and a two-way oil port B (1403) are arranged inside the columnar oil passage (1401); the two-way oil port A (1402) and the two-way oil port B (1403) are designed to be offset; one-way oil ball heads (15) are arranged at both ends of the injector oil return pipe (103); the one-way oil ball head (15) at one end of the injector oil return pipe (103) is connected to the internal thread of the connecting block oil outlet (1012) through the hinge bolt (14); and the one-way oil ball head (15) at the other end of the injector oil return pipe (103) is connected to the space integration part (4) through the hinge bolt (14).

5. A common rail fuel low pressure circuit system according to claim 1, characterized in that: The common rail oil return portion (2) comprises a hinge bolt (14) and a common rail oil return pipe (201), and one-way oil passing ball heads (15) are provided at both ends of the common rail oil return pipe (201). The one-way oil passing ball head (15) at one end of the common rail oil return pipe (201) is connected to the high-pressure oil rail (9) via the hinge bolt (14), and the one-way oil passing ball head (15) at the other end of the common rail oil return pipe (201) is connected to the space integration portion (4) via the hinge bolt (14).

6. A common rail fuel low pressure circuit system according to claim 1, characterized in that: The high-pressure oil pump return oil part (3) comprises a hinge bolt (14), an oil pump return oil pipe (301), a two-way oil ball head (302) and a plunger return oil pipe (303); one end of the oil pump return oil pipe (301) and one end of the plunger return oil pipe (303) are connected via the two-way oil ball head (302); the other end of the oil pump return oil pipe (301) is provided with a one-way oil ball head (15) and is connected to the spatial integration part (4) through cooperation with the hinge bolt (14); the other end of the plunger return oil pipe (303) is provided with a one-way oil ball head (15) and is connected to the high-pressure oil pump (10) through cooperation with the hinge bolt (14).

7. A common rail fuel low pressure circuit system according to claim 1, characterized in that: The spatial integration part (4) comprises an oil return integration block (401) and a fixing bolt (17). The oil return integration block (401) is provided with a blind hole oil passage (4011). The blind hole oil passage (4011) is provided with a common rail pipe oil return part oil inlet (4012), an injector oil return part oil inlet (4013), a total oil return part oil outlet (4014) and a high-pressure oil pump oil return part oil inlet (4015). The above-mentioned oil inlets and outlets are all provided with internal threads. The oil return integration block (401) is provided with a threaded through hole B (4016) for matching with the fixing bolt (17).

8. The common rail fuel low pressure circuit system according to claim 1, characterized in that: The total oil return portion (5) comprises a conversion joint (501), a bent oil return steel pipe (502), an oil return rubber pipe (503) and a total oil return joint (504); the cross section of the conversion joint (501) is in the shape of a "Z" character; the conversion joint (501) is provided with a central through hole (5011) running vertically through; a sealing cone surface (5012) is provided at the mouth of the central through hole (5011); an external thread is provided on the outer wall of the central through hole (5011); one end of the bent oil return steel pipe (502) is provided with a sealing spherical surface (5021); The sealing spherical surface (5021) cooperates with the sealing conical surface (5012) of the conversion joint (501); a locking nut (5022) is sleeved on the body of the bent oil return steel pipe (502); the internal thread of the locking nut (5022) cooperates with the external thread of the conversion joint (501); the other end of the bent oil return steel pipe (502) is connected to one end of the oil return rubber pipe (503); the other end of the oil return rubber pipe (503) is connected to a total oil return joint (504); and the total oil return joint (504) is connected to the oil tank.

9. A common rail fuel low pressure circuit system according to claim 4, characterized in that: A combined sealing gasket (16) is provided at the connection between the hinge bolt (14) and the one-way oil-passing ball head (15).

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