CN111907324A

CN111907324A - Fuel system and vehicle

Info

Publication number: CN111907324A
Application number: CN201910380656.3A
Authority: CN
Inventors: 李泉; 卢江; 曾志新
Original assignee: Guangzhou Automobile Group Co Ltd
Current assignee: Guangzhou Automobile Group Co Ltd
Priority date: 2019-05-08
Filing date: 2019-05-08
Publication date: 2020-11-10

Abstract

The invention belongs to the technical field of automobile fuel systems, and relates to a fuel system and a vehicle. The fuel oil system comprises a fuel oil tank, an oil pump, a liquid collector assembly, a steam pipe, a circulating pipe, an oil filling pipe and a carbon tank, wherein the oil pump and the liquid collector assembly are arranged on the fuel oil tank; the steam pipe is connected between the carbon tank and the liquid collector assembly, the first end of the circulating pipe is connected to the steam pipe and communicated with the steam pipe, and the second end of the circulating pipe is connected to the second end of the oil filling pipe and communicated with the oil filling pipe. During the refueling process of the fuel system, oil gas in the fuel tank can flow back into the fuel tank through the circulating pipe, and meanwhile, the requirements of national six regulations can be met.

Description

Fuel system and vehicle

Technical Field

The invention belongs to the technical field of automobile fuel systems, and particularly relates to a fuel system and a vehicle.

Background

In the part of provinces and cities in China, stricter automobile emission regulations (emission regulations in the sixth stage of China) are about to be implemented, the limit of evaporative emission of the new regulations is only 1/3 of the emission regulations in the fifth stage of China, meanwhile, the requirements of refueling emission, online fuel leakage diagnosis and emission durability are increased, and the design of a fuel system is confronted with severe challenges due to the strict emission requirements. The existing national fifth fuel system needs to be comprehensively upgraded to meet the requirements of lower evaporative emission and newly added refueling emission and emission durability.

However, the existing fuel system still cannot meet the limit requirements of evaporative emission and refueling emission of the national six-regulation. Therefore, there is a need to design a low emission fuel system to meet the stringent national six code requirements.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the technical problem that the existing fuel system is difficult to meet the strict national six-regulation requirement, the fuel system is provided.

In order to solve the technical problem, in one aspect, an embodiment of the present invention provides a fuel system, including a fuel tank, an oil pump, a liquid collector assembly, a steam pipe, a circulating pipe, a filler pipe, and a canister, where the oil pump and the liquid collector assembly are mounted on the fuel tank, the liquid collector assembly is connected to the oil pump, a first end of the filler pipe is connected to the fuel tank, and a second end of the filler pipe is provided with a filler opening;

the steam pipe is connected between the carbon tank and the liquid collector assembly, the first end of the circulating pipe is connected to the steam pipe and communicated with the steam pipe, and the second end of the circulating pipe is connected to the second end of the oil filling pipe and communicated with the oil filling pipe.

According to the fuel system provided by the embodiment of the invention, the circulating pipe connected between the steam pipe and the second end of the oil filling pipe is used for realizing that oil gas in the fuel tank can flow back into the fuel tank through the circulating pipe in the oil filling process of the fuel system, so that the condition that a larger carbon tank is required to be designed to adsorb all oil gas discharged from the fuel tank so as to control the emission of the oil filling process to meet the requirements of the national six regulations is avoided. Meanwhile, the load of the carbon tank is reduced, the large carbon tank is not needed to meet the emission requirement, the development cost, the weight and the space required by arrangement of the six-model-of-country vehicle are reduced, and a foundation can be laid for the development of the six-model-of-country vehicle.

Optionally, the steam pipe includes a first pipe section, a second pipe section, a third pipe section, and a three-way joint, the first pipe section is connected between a first interface of the three-way joint and the carbon canister, the second pipe section is connected between a second interface of the three-way joint and the liquid trap assembly, a first end of the third pipe section is connected with a third interface of the three-way joint, and a second end of the third pipe section is connected to the first end of the circulation pipe.

Optionally, the pipe diameter of the first pipe section is the same as that of the second pipe section, the pipe diameter of the third pipe section is smaller than that of the first pipe section, and the pipe diameter of the third pipe section is the same as that of the circulation pipe.

Optionally, a throttling device for controlling the negative pressure of the oil filling opening is arranged on the first end of the circulation pipe.

Optionally, the fuel filler pipe includes hard tube and hose, the first end of hard tube with the first end of hose is connected, the oil filler hole sets up the second end of hard tube, the second end of hose is connected on the fuel tank.

Optionally, the hard tube is a metal hard tube, the hose is a permeation-resistant low-permeability multilayer rubber tube, the oil filling pipe further comprises a first clamp, and the first end of the hard tube is connected with the first end of the hose through the first clamp.

Optionally, the fuel system further comprises an anti-return valve, a first through hole is formed in the side wall of the fuel tank, the anti-return valve is arranged on the first through hole, the second end of the hose is connected with the first end of the anti-return valve, and the second end of the anti-return valve faces towards the inner cavity of the fuel tank.

Optionally, the liquid trap assembly includes liquid trap, pressure sensor, first connecting pipe and second connecting pipe, be provided with first connector and second connector on the liquid trap, first connecting pipe is connected first connector with between the oil pump, the second connecting pipe is connected the second connector with between the steam pipe, pressure sensor installs on the second connecting pipe.

Optionally, the fuel system further comprises a gravity valve, a second through hole is formed in the top wall of the fuel tank, and the gravity valve is arranged on the second through hole;

the liquid collector assembly further comprises a third connecting pipe, a third connecting port is further arranged on the liquid collector, and the third connecting pipe is connected between the third connecting port and the gravity valve.

Optionally, the fuel system further comprises a fuel filler cap, the fuel filler cap is mounted at the second end of the fuel filler pipe to open or close the fuel filler opening, and a sealing ring with a fluororubber material and a check valve are arranged on the fuel filler cap.

Optionally, a trapezoidal clamping opening which surrounds the fuel tank for one circle is formed in the side wall of the fuel tank.

In another aspect, the embodiment of the invention further provides a vehicle, which comprises the fuel system.

Drawings

FIG. 1 is a schematic illustration of a fuel system provided in accordance with an embodiment of the present invention;

FIG. 2 is a cross-sectional view of a fuel system provided in accordance with an embodiment of the present invention;

FIG. 3 is another cross-sectional view of a fuel system provided in an embodiment of the present invention.

The reference numerals in the specification are as follows:

1. a fuel tank; 11. a trapezoidal clamping opening; 12. mounting grooves; 13. a second through hole; 14. a third through hole; 15. an annular groove; 16. an O-shaped sealing ring; 17. a metal chuck; 18. a metal insert ring;

2. an oil pump; 21. an oil pump body; 22. an FLVV valve; 23. a male connector;

3. a liquid collector assembly; 31. a liquid collector; 32. a pressure sensor; 33. a first connecting pipe; 34. a second connecting pipe; 35. a third connecting pipe;

4. a steam pipe; 41. a first tube section; 42. a second tube section; 43. a third tube section; 44. a three-way joint;

5. a circulation pipe;

6. an oil filler tube; 61. a hard tube; 62. a hose; 63. a first clamp; 64. a second clamp;

7. a carbon tank; 71. an adsorption port; 72. an atmosphere opening is communicated;

8. an anti-reflux valve;

9. a gravity valve;

10. an oil filling cover.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1 to 3, the fuel system according to the embodiment of the present invention includes a fuel tank 1, an oil pump 2, a liquid trap assembly 3, a steam pipe 4, a circulation pipe 5, a filler pipe 6, and a canister 7, wherein the oil pump 2 and the liquid trap assembly 3 are mounted on the fuel tank 1, the liquid trap assembly 3 is connected to the oil pump 2, a first end of the filler pipe 6 is connected to the fuel tank 1, and a second end of the filler pipe 6 is provided with a filler opening.

The steam pipe 4 is connected between the carbon tank 7 and the liquid collector assembly 3, a first end of the circulation pipe 5 is connected to the steam pipe 4 and communicated with the steam pipe 4, and a second end of the circulation pipe 5 is connected to a second end of the oil filling pipe 6 and communicated with the oil filling pipe 6.

According to the fuel system provided by the embodiment of the invention, the circulating pipe 5 connected between the steam pipe 4 and the second end of the oil filling pipe 6 is adopted, so that the oil gas in the fuel tank 1 can flow back to the fuel tank 1 through the circulating pipe 5 in the oil filling process of the fuel system, and the condition that a larger carbon tank 7 is required to be designed to adsorb all the oil gas discharged from the fuel tank 1 so as to control the emission in the oil filling process to meet the requirements of the national six regulations is avoided. Meanwhile, the load of the carbon tank 7 is reduced, the large carbon tank 7 is not needed to meet the emission requirement, the development cost, the weight and the space of arrangement requirements of the six-country vehicle type are reduced, and a foundation can be laid for the development of the six-country vehicle type.

In one embodiment, as shown in FIG. 1, the fuel tank 1 is a multi-layer plastic profile. The upper surface of the fuel tank 1 is provided with a third through hole 14 for assembling the oil pump 2. Fuel tank 1 still includes metal chuck 17 and metal caulking ring 18, oil pump 2 passes through back in the third through-hole 14 on the fuel tank 1 packs into fuel tank 1, rethread metal chuck 17 and the cooperation of metal caulking ring 18, will oil pump 2 fastening assembly in on the fuel tank 1, adopt metal chuck 17 and the fastening oil pump 2 of metal caulking ring 18, can avoid the Hydrocarbon (HC) emission that causes because of assembly moment decline behind the durable rise.

As shown in fig. 2, the third through hole 14 is further provided with an annular groove 15 at the periphery thereof, and the fuel tank 1 further includes an O-ring 16 fitted in the annular groove 15. The oil pump 2 is assembled and sealed by an O-shaped sealing ring 16 in an annular groove 15 on the fuel tank 1, and HC emission of an assembling surface of the oil pump 2 is reduced. The oil pump 2 is of a plastic structure.

In one embodiment, as shown in fig. 1 and 2, the oil pump 2 includes an oil pump body 21 and an overflow valve (FLVV valve 22), the oil pump body 21 is mounted on the fuel tank 1 through the third through hole 14, and the FLVV valve 22 is mounted on a flange of the oil pump 2, so as to avoid additionally forming a through hole for welding the FLVV valve 22 on the fuel tank 1, thereby further reducing the permeation amount of HC through the welding surface. Meanwhile, the FLVV valve 22 is arranged on the oil pump body 21, so that the cost of the national six-fuel system can be further reduced.

In one embodiment, as shown in fig. 1, the liquid trap assembly 3 is plugged into the male connector 23 on the flange of the oil pump 2 through a female connector, and then is connected with the male connector on the steam pipe 4 through a female connector in a quick-plugging manner.

In one embodiment, as shown in fig. 1 and 2, a mounting groove 12 for mounting the liquid trap assembly 3 is formed in the fuel tank 1, and the liquid trap assembly 3 is mounted in the mounting groove 12 of the fuel tank 1 by a clip at the bottom of the liquid trap assembly.

In one embodiment, as shown in fig. 1, the interior of the canister 7 has a dual-cavity structure, the shell of the canister 7 is made of a low-permeability nylon material by injection molding to block permeation of HC through the shell, and the interior of the canister 7 is filled with cylindrical carbon powder to adsorb oil and gas, so as to reduce escape of HC through the atmospheric vent 72.

In one embodiment, as shown in fig. 1, the steam pipe 4 includes a first pipe section 41, a second pipe section 42, a third pipe section 43, and a three-way joint 44, the first pipe section 41 is connected between a first port of the three-way joint 44 and the carbon canister 7, the second pipe section 42 is connected between a second port of the three-way joint 44 and the liquid trap assembly 3, a first end of the third pipe section 43 is connected to a third port of the three-way joint 44, and a second end of the third pipe section 43 is connected to a first end of the circulation pipe 5, so as to realize connection between the steam pipe 4 and the liquid trap assembly 3, the carbon canister 7, and the circulation pipe 5.

The steam pipe 4 is a multilayer nylon pipe, and joints of the first pipe section 41, the second pipe section 42 and the third pipe section 43 are all optional pieces. A sealing ring is arranged at the compression joint of the three-way joint 44 and the steam pipe 4 so as to reduce HC emission.

In one embodiment, as shown in fig. 1, the pipe diameter of the first pipe segment 41 is the same as that of the second pipe segment 42, the pipe diameter of the third pipe segment 43 is smaller than that of the first pipe segment 41, and the pipe diameter of the third pipe segment 43 is the same as that of the circulation pipe 5, so that part of the oil gas in the second pipe segment 42 flows to the circulation pipe 5 through the third pipe segment 43 and then flows back to the fuel tank 1 through the fuel filler pipe 6.

In one embodiment, the first pipe section 41 and the second pipe section 42 are both nylon pipes with a pipe diameter of 16mm, the third pipe section 43 is nylon pipe with a pipe diameter of 8mm, and the circulation pipe 5 is a metal pipe with an outer diameter of 8 mm.

The steam pipe 4 is connected through three way connection 44 first pipeline section 41, second pipeline section 42 and third pipeline section 43, the second end of third pipeline section 43 is passed through female joint and is in with the setting the male joint of the first end of circulating pipe 5 is connected, first pipeline section 41 pass through female joint with adsorption port 71 on the carbon tank 7 is connected, thereby realizes carbon tank 7 adsorbs the oil gas and refuels the part oil gas circulation of process, reduces the load of carbon tank 7, has avoided connecting need two independent pipelines with circulating pipe 5 to fill oil pipe 6 between fuel tank 1 and the carbon tank 7, causes the cost and arranges the problem that the space rises. Meanwhile, the design of the three-way joint 44 can save the length cost, the arrangement space and the like of the pipeline.

In one embodiment, the first end of the circulation tube 5 is provided with a throttle for controlling the negative pressure at the oil filling opening. Preferably, the throttling device is a throttling orifice plate or a throttling valve. In one embodiment, the first end of the circulation tube 5 is provided with an orifice.

Through the design orifice on circulating pipe 5 and the matching have realized refueling in-process, the fuel gas accessible in the fuel tank 1 circulating pipe 5 backward flow gets into fuel tank 1 has avoided needing to design bigger carbon tank 7 and has adsorbed whole oil gas of discharge in the fuel tank 1 to the emission of control refueling process reaches the regulation requirement.

In one embodiment, as shown in FIG. 1, the filler tube 6 comprises a rigid tube 61 and a flexible tube 62, wherein a first end of the rigid tube 61 is connected to a first end of the flexible tube 62, the filler opening is disposed at a second end of the rigid tube 61, and a second end of the flexible tube 62 is connected to the fuel tank 1.

The hard pipe 61 is a metal hard pipe, and the hose 62 is a permeation-resistant low-permeability multilayer rubber pipe.

In one embodiment, as shown in fig. 1, the hard tube 61 and the circulation tube 5 are connected by welding to fix the hard tube 61 and the circulation tube 5.

In one embodiment, as shown in FIG. 1, the fuel filler tube 6 further includes a first clamp 63, and the first end of the rigid tube 61 and the first end of the flexible tube 62 are connected by the first clamp 63. First clamp 63 chooses for use the elasticity compensation clamp to the compensation regulation hose 62 with assembly moment between the hard tube 61 avoids the assembly pine to take off and causes HC to reveal.

In one embodiment, as shown in fig. 1, the fuel system further includes an anti-backflow valve (ICV valve) 8, a first through hole is formed in a sidewall of the fuel tank 1, the anti-backflow valve 8 is disposed on the first through hole, a second end of the hose 62 is connected to a first end of the anti-backflow valve 8, and a second end of the anti-backflow valve 8 faces the inner cavity of the fuel tank 1. Prevent the welding of backward flow valve 8 in the first through-hole, prevent that backward flow valve 8 is spring baffle structure check valve for prevent in the fuel tank 1 fluid passes through prevent that backward flow valve 8 flows into to in the hard tube 61.

In one embodiment, as shown in FIG. 1, the filler tube 6 further includes a second clip 64, and the hose 62 and the anti-drainback valve 8 are connected by the second clip 64. The second clamp 64 is an elastic compensation clamp for compensation adjustment, so that the assembly torque between the hose 62 and the anti-backflow valve 8 is compensated and adjusted, and HC leakage caused by loosening of the assembly is avoided.

In one embodiment, as shown in fig. 1, the liquid trap assembly 3 includes a liquid trap 31, a pressure sensor 32, a first connection pipe 33 and a second connection pipe 34, the liquid trap 31 is provided with a first connection port and a second connection port, the first connection pipe 33 is connected between the first connection port and the oil pump 2, the second connection pipe 34 is connected between the second connection port and the steam pipe 4, and the pressure sensor 32 is mounted on the second connection pipe 34. The inside of the liquid collector 31 is of a labyrinth structure, so that oil can flow back in the liquid collector. The pressure sensor 32 is used to detect the vapor pressure in the fuel tank 1.

In one embodiment, as shown in fig. 1 and 3, the fuel system further includes a gravity valve 9, a second through hole 13 is formed on a top wall of the fuel tank 1, and the gravity valve 9 is disposed on the second through hole 13. The gravity valve 9 is welded in the second through hole 13, so that the gravity valve 9 is mounted on the fuel tank 1.

The liquid collector assembly 3 further comprises a third connecting pipe 35, a third connecting port is further arranged on the liquid collector 31, and the third connecting pipe 35 is connected between the third connecting port and the gravity valve 9.

In an embodiment, the gravity valve 9 and the anti-backflow valve 8 are both 2K valves, the material of the welding surface between the 2K valve and the fuel tank 1 and the material of the outer layer of the fuel tank 1 are both High Density Polyethylene (HDPE), and the upper portion of the 2K valve is made of a nylon material for blocking HC permeation.

In the embodiment shown in fig. 1, two gravity valves 9 are provided, the fuel tank 1 is substantially rectangular, one gravity valve 9 is arranged at a first vertex angle of the fuel tank 1, the other gravity valve 9 is arranged at a second vertex angle opposite to the first vertex angle on the fuel tank 1, and the third connecting pipe 35 is connected with the third connecting port of the liquid collector 31 while connecting the two gravity valves 9, so that the oil flowing to the two gravity valves 9 can flow into the liquid collector 31 and then flow back into the fuel tank 1 from the liquid collector 31.

In other embodiments not shown, the gravity valve 9 may be provided in other numbers, such as 1.

In one embodiment, as shown in fig. 1, the first connection pipe 33 is inserted into the male connector 23 of the flange of the oil pump 2 through a female connector, the second connection pipe 34 is inserted into the male connector of the steam pipe 4 through a female connector, and the liquid trap 31 is inserted into the female connector of the end of the third connection pipe 35 through a male connector.

In one embodiment, as shown in fig. 1 and 3, the fuel system further includes a fuel filler cap 10, and the fuel filler cap 10 is installed at the second end of the fuel filler pipe 6 to open or close the fuel filler opening. The oil filling cover 10 is of a threaded structure and is fastened through threaded tightening and threaded matching on the hard pipe 61, and meanwhile, a sealing ring made of a fluororubber material is further arranged on the oil filling cover 10 to achieve sealing between the oil filling cover 10 and the hard pipe 61 and reduce HC emission at the assembly position of the oil filling cover 10. In addition, the oil filling cover 10 is provided with a one-way valve, and the emission is further reduced compared with a five-state positive and negative pressure two-way valve.

In one embodiment, as shown in fig. 1 and 3, a trapezoidal clip 11 is formed on a sidewall of the fuel tank 1 to surround the fuel tank 1. The trapezoidal clamping opening 11 can ensure that the clearance between the separation layers of the fuel tank 1 is smaller during mold closing, and the HC permeation quantity passing through the trapezoidal clamping opening 11 is reduced.

The working principle of the fuel system provided by the embodiment of the invention is as follows:

(1) refueling process

In the refueling process, oil gas in the fuel tank 1 flows to the liquid collector 31 through the FLVV valve 22 and then is divided into two parts through the steam pipe 4 connected with the liquid collector 31, one part of the oil gas flows through the circulating pipe 5 and then enters the fuel tank 1 along with the refueling oil liquid through the refueling pipe 6, the other part of the oil gas flows through the adsorption port 71 of the carbon tank 7 and enters the carbon tank 7 to be adsorbed, and the adsorbed oil gas in the carbon tank 7 enters the engine to be combusted through negative pressure desorption formed at an engine manifold or an air pipe.

When the oil filling amount reaches the set rated volume, the floater of the FLVV valve 22 floats upwards, the passage between the FLVV valve 22 and the liquid collector 31 is closed, the pressure in the fuel tank 1 rises sharply, and the oil liquid in the fuel tank 1 returns to the oil filling pipe 6 through the anti-backflow valve 8 under the action of the pressure. When the returned oil touches the sensor hole of the oil gun, the gun jump of the oil gun is completed.

In the process of refueling, oil gas with a certain flow rate returned by the circulating pipe 5 forms negative pressure at the refueling port part of the refueling pipe 6, and the oil gas is prevented from volatilizing to enter the atmosphere through the refueling port. Meanwhile, the hard pipe 61 with the smaller pipe diameter forms a liquid seal in the refueling process, so that the oil gas in the fuel tank 1 is prevented from returning to the atmosphere pollution environment through the refueling pipe 6, the oil gas in the fuel tank 1 cannot be discharged to the atmosphere through the refueling port of the refueling pipe 6, but enters the carbon tank 7 to be adsorbed, and the HC emission in the refueling process is effectively controlled.

(2) Vehicle driving process

When the pressure in the fuel tank 1 does not reach the opening pressure of the gravity valve 9 during the running of the vehicle, the oil gas in the fuel tank 1 flows through the liquid collector 31 through the FLVV valve 22, then flows through the second pipe section 42 and the first pipe section 41 of the steam pipe 4, and is adsorbed by the carbon tank 7 through the adsorption port 71. When the pressure in the fuel tank 1 reaches the opening pressure of the gravity valve 9, the oil gas in the fuel tank 1 flows into a liquid collector 31 through the gravity valve 9 and then flows into the carbon tank 7 to be adsorbed. The columnar carbon powder filled in the double cavities of the carbon tank 7 has enough capacity to adsorb oil gas, so that the oil gas in the fuel tank 1 is prevented from directly entering the atmosphere, and evaporation and discharge are controlled.

When the fuel tank 1 shakes during the running of the vehicle, the oil liquid in the fuel tank 1 flows into the liquid trap 31 through the gravity valve 9 and the FLVV valve 22, and is collected by the liquid trap 31. The oil flowing into the liquid collector 31 due to the shaking of the vehicle can flow back into the fuel tank 1, thereby avoiding the failure of carbon powder in the carbon tank 7 and the misdiagnosis of the pressure sensor 32 for the diagnosis of the On-Board Diagnostics (OBD).

In order to further reduce HC leakage through the welding area and the connection part, the fuel system provided by the embodiment of the invention adopts the following modes: through second through-hole 13 welding 2K gravity valve 9 on the fuel tank 1, pass through first through-hole welding 2K anti-return valve 8, the thickening on the fuel tank 1 the 1 barrier layer proportion of fuel tank, with the material upgrading of adding oil cap 10 for fluororubber, change oil cap 10 into the check valve, upgrade hose 62 for low permeability rubber hose 62 and hard tube 61 between through the elastic compensation clamp connection, hose 62 and anti-return valve 8 between through the elastic compensation clamp connection and oil pump 2 passes through the installation of metal chuck 17.

The vehicle provided by the embodiment of the invention comprises the fuel system.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A fuel oil system is characterized by comprising a fuel oil tank, an oil pump, a liquid collector assembly, a steam pipe, a circulating pipe, an oil filling pipe and a carbon tank, wherein the oil pump and the liquid collector assembly are arranged on the fuel oil tank;

2. The fuel system of claim 1, wherein the steam pipe includes a first pipe section, a second pipe section, a third pipe section, and a tee joint, the first pipe section being connected between a first port of the tee joint and the carbon canister, the second pipe section being connected between a second port of the tee joint and the liquid trap assembly, a first end of the third pipe section being connected to a third port of the tee joint, and a second end of the third pipe section being connected to the first end of the circulation pipe.

3. The fuel system according to claim 2, wherein the pipe diameter of said first pipe section is the same as the pipe diameter of said second pipe section, the pipe diameter of said third pipe section is smaller than the pipe diameter of said first pipe section, and the pipe diameter of said third pipe section is the same as the pipe diameter of said circulation pipe.

4. The fuel system as recited in claim 2, wherein a throttle device for controlling a negative pressure of the fuel filler is provided on the first end of the circulation pipe.

5. The fuel system of claim 1, wherein the filler tube includes a rigid tube and a flexible tube, a first end of the rigid tube being connected to a first end of the flexible tube, the filler opening being disposed at a second end of the rigid tube, and a second end of the flexible tube being connected to the fuel tank.

6. The fuel system of claim 5, wherein the rigid conduit is a metal rigid conduit, the flexible conduit is a permeation resistant low permeability multi-layer rubber conduit, and the filler conduit further includes a first clamp, and wherein the first end of the rigid conduit is connected to the first end of the flexible conduit by the first clamp.

7. The fuel system as recited in claim 5, further comprising a back-flow prevention valve, wherein a first through hole is formed in a side wall of the fuel tank, the back-flow prevention valve is disposed in the first through hole, a second end of the hose is connected to a first end of the back-flow prevention valve, and a second end of the back-flow prevention valve faces the inner cavity of the fuel tank.

8. The fuel system as recited in claim 1, wherein the liquid trap assembly includes a liquid trap, a pressure sensor, a first connection pipe and a second connection pipe, the liquid trap being provided with a first connection port and a second connection port, the first connection pipe being connected between the first connection port and the oil pump, the second connection pipe being connected between the second connection port and the steam pipe, the pressure sensor being mounted on the second connection pipe.

9. The fuel system as recited in claim 8, further comprising a gravity valve, wherein a second through hole is provided on a top wall of the fuel tank, and the gravity valve is provided on the second through hole;

10. The fuel system as recited in any one of claims 1 to 9, further comprising a filler cap mounted on the second end of the filler pipe to open or close the filler port, the filler cap being provided with a packing with a fluororubber material and a check valve.

11. The fuel system as recited in any one of claims 1 to 9, wherein a trapezoidal clip is formed on a side wall of the fuel tank so as to surround the fuel tank.

12. A vehicle comprising a fuel system according to any one of claims 1-11.