CN112343745A

CN112343745A - Fuel oil system and control method thereof

Info

Publication number: CN112343745A
Application number: CN202011131038.4A
Authority: CN
Inventors: 李云华; 高慎勇
Original assignee: Weichai Power Co Ltd
Current assignee: Weichai Power Co Ltd
Priority date: 2020-10-21
Filing date: 2020-10-21
Publication date: 2021-02-09

Abstract

The invention discloses a fuel system and a control method thereof, wherein the fuel system comprises a fuel tank, a high-pressure oil pump, a common rail pipe, a plurality of first high-pressure oil pipes, a high-pressure unit and an engine; the high-pressure unit comprises a pressure amplifying chamber, a pressure amplifying part and an oil removing tank; the pressure amplification chamber is communicated with each first high-pressure oil pipe; the pressure amplification part comprises a pressurizing oil pipe, a first piston and a second piston, the pressurizing oil pipe comprises a first part and a second part which are communicated with each other and have the same central line, the inner diameter of the first part is smaller than that of the second part, one end of the first part, which is far away from the second part, is communicated with the pressure amplification chamber, the first piston is in sealing fit with the inner wall of the second part, one end of the second piston is in sealing fit with the inner wall of the first part, and the other end of the second piston is abutted to the first piston; the oil removing tank is communicated with a chamber of the second part between the first piston and the first part and is provided with an oil discharge port, and a second control valve is arranged at the oil discharge port. The high-pressure unit in the fuel system is simple in structure and can save equipment cost.

Description

Fuel oil system and control method thereof

Technical Field

The invention relates to the technical field of engines, in particular to a fuel system and a control method thereof.

Background

In the prior art, in order to reduce oil consumption and improve power and reliability, a fuel system generally requires that a variable fuel injection rule can be realized when the fuel system injects fuel, so that the fuel system can adjust an injection strategy of a fuel injector according to different working conditions of an engine, and reduce emission and oil consumption. However, in a common fuel system, each fuel injector needs to be additionally provided with a pressure amplifier and a control valve for controlling the pressure amplifier to pressurize, and the fuel is pressurized by the pressure amplifier to realize a variable fuel injection law.

Disclosure of Invention

The invention provides a fuel system and a control method thereof, the fuel system can realize the variable fuel injection rule when a plurality of fuel injectors inject fuel, the control operation is simple, the structure is simple, and the equipment cost can be saved.

In order to achieve the purpose, the invention provides the following technical scheme:

a fuel system, comprising: the system comprises a fuel tank, a high-pressure oil pump, a common rail pipe, a plurality of first high-pressure oil pipes, a high-pressure unit and an engine; the fuel tank is connected with the common rail pipe through the high-pressure oil pump, a plurality of cylinders are arranged in a body of the engine, an oil injector is arranged in each cylinder, a first control valve used for controlling fuel injection is arranged on each oil injector, the first end of a first high-pressure oil pipe is connected with the common rail pipe, the second end of the first high-pressure oil pipe is connected with the oil injectors in a one-to-one correspondence mode, a communication area is arranged between the first end and the second end, and a one-way valve with an opening facing the second end is arranged between the communication area and the first end; the high-pressure unit comprises a pressure amplifying chamber, a pressure amplifying part and an oil removing tank; wherein the content of the first and second substances,

the pressure amplification chamber is communicated with the communication area on each first high-pressure oil pipe;

the pressure amplification part comprises a pressurized oil pipe, a first piston and a second piston, the pressurized oil pipe comprises a first part and a second part which are communicated with each other and have the same central line, the inner diameter of the first part is smaller than that of the second part, one end of the first part, which is far away from the second part, is communicated with the pressure amplification chamber, the first piston is positioned in the second part and is in sealing fit with the inner wall of the second part, one end of the second piston is in sealing fit with the inner wall of the first part, and the other end of the second piston is abutted against the first piston;

go the oil tank with the second part is located first piston with cavity intercommunication between the first part, just go the oil tank with the second part is located first piston with keep away from same high-pressure oil supply line is connected to the cavity between the one end of first part, go to have the oil discharge port on the oil tank, oil discharge port department is provided with the second control valve who is used for controlling the oil discharge.

In the fuel system provided by the embodiment of the invention, the fuel in the fuel tank can be pressurized by the high-pressure oil pump and then supplied to the common rail pipe for pressure stabilization, and then the fuel is supplied to the fuel injector for injection by the first high-pressure oil pipe, the high-pressure unit can pressurize the high-pressure fuel pressurized by the high-pressure oil pump again, wherein the high-pressure unit comprises a pressure amplification chamber, a pressure amplification part and a fuel removal tank, the pressure amplification part comprises a pressurized oil pipe, a first piston and a second piston, the first piston divides a second part of the pressurized oil pipe into a first cavity between the first piston and the first part and a second cavity between the first piston and one end of the second part far away from the first part, the fuel removal tank is communicated with the first cavity, the fuel removal tank and the second cavity are connected with the same oil supply high-pressure pipeline, and when the high-pressure unit does not pressurize the fuel, the fuel fills the pressure amplification chamber, the first cavity and the, the pressure of pressure amplification chamber, first cavity and second cavity equals, the pressure balance of first piston both sides, and when needs high-pressure unit pressurizes the fuel, can open the second control valve, the fuel in the second cavity flows by the oil discharge outlet, the pressure balance of first piston both sides is destroyed, first piston can drive the second piston motion and pressurize the fuel in the pressure amplification chamber, the pressure amplification factor of fuel is the cross sectional area of first piston and the cross sectional area of second piston's ratio, for preventing by the then backward flow after the high-pressure unit pressurization, be provided with the check valve on the first high pressure fuel pipe. In the fuel system, the fuel oil which is conveyed to the plurality of fuel oil injectors for injection is pressurized again through the high-pressure unit and the second control valve, the variable fuel injection rule when the plurality of fuel oil injectors inject the fuel oil can be realized, the control operation is simple, the structure is simple, and the equipment cost can be saved.

Optionally, a return spring is disposed between an end of the second portion adjacent to the first portion and the first piston.

Optionally, the system further comprises a second high-pressure oil pipe, the second high-pressure oil pipe is communicated with the communicating area of each first high-pressure oil pipe, and the pressure amplification chamber is communicated with the communicating area of each first high-pressure oil pipe through the second high-pressure oil pipe.

Optionally, the de-oiling tank is in communication with the common rail, and the chamber of the second part between the first piston and the end remote from the first part is in communication with the common rail.

Optionally, each of the first high pressure fuel lines is connected to the fuel injector by a high pressure connector.

Optionally, the first high pressure oil pipe is integrally connected with the high pressure connector.

Optionally, the fuel injection system further comprises a control unit, the control unit is in signal connection with the first control valve and the second control valve, and the control unit is used for controlling the working states of the plurality of first control valves and the plurality of second control valves so as to enable the fuel injection rule of the fuel injector to be variable.

The invention also provides a control method of the fuel system, which comprises the following steps:

determining the working condition of the engine according to the rotating speed data and the load data of the engine;

and controlling the working states of the plurality of first control valves and the plurality of second control valves according to the working condition of the engine so as to enable the oil injection rule of the oil injector to be variable.

Optionally, the controlling the working states of the first control valve and the second control valve according to the working condition of the engine includes:

when the engine is in a starting working condition or a regeneration working condition, controlling some first control valves in the plurality of first control valves to be opened in sequence according to a first preset sequence;

and when the engine is in a normal operation working condition, all the first control valves in the plurality of first control valves are controlled to be opened in sequence according to a second preset sequence.

Optionally, when the engine is in a normal operating condition, controlling all the first control valves of the plurality of first control valves to open in sequence according to a second preset sequence, including:

when the engine is in a working condition of low rotating speed and small load, the second control valve is controlled not to be opened in the oil injection process of each oil injector;

when the engine is in a working condition of medium and low rotating speed and large load, the second control valve is controlled to be opened first, and the first control valve is controlled to be opened later in the oil injection process of each oil injector, so that the oil injectors can inject oil according to a slope type oil injection rule;

when the engine is in a working condition of medium-low rotating speed and large load, the first control valve is controlled to be opened first, and the second control valve is controlled to be opened later in the oil injection process of each oil injector, so that the oil injectors can inject oil according to a boot-shaped oil injection rule;

when the engine is in a high-rotation-speed working condition, the second control valve is controlled to be opened first and then the first control valve is controlled to be opened in the oil injection process of each oil injector, so that the oil injectors can inject oil according to a rectangular oil injection rule.

Drawings

FIG. 1 is a schematic structural diagram of a fuel system according to an embodiment of the present invention;

FIG. 2 is a flow chart of a control method of a fuel system according to an embodiment of the present invention;

FIG. 3 is a control flow chart of a fuel system according to an embodiment of the present invention.

Icon:

1-a fuel tank; 2-a high-pressure oil pump; 3-common rail pipe; 4-a first high pressure tubing; 41-one-way valve; 42-high voltage connector; 5-a high-voltage unit; 51-a pressure amplification chamber; 52-a pressure amplification section; 521-a pressurized oil pipe; 5211-first part; 5212-second part; 522-a first piston; 523-second piston; 53-removing an oil tank; 531-oil drain; 532-second control valve; 6-an engine; 61-a cylinder; 62-fuel injector; 7-second high pressure oil pipe.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, the present invention provides a fuel system, including: the system comprises a fuel tank 1, a high-pressure oil pump 2, a common rail pipe 3, a plurality of first high-pressure oil pipes 4, a high-pressure unit 5 and an engine 6; the fuel tank 1 is connected with the common rail pipe 3 through the high-pressure oil pump 2, a plurality of cylinders 61 are arranged in a body of the engine 6, an oil sprayer 62 is arranged in each cylinder 61, a first control valve used for controlling fuel oil injection is arranged on each oil sprayer 62, a first end of a first high-pressure oil pipe 4 is connected with the common rail pipe 3, a second end of the first high-pressure oil pipe 4 is correspondingly connected with the oil sprayers 62 one by one, a communication area is arranged between the first end and the second end, and a one-way valve 41 with an opening facing the second end is arranged between the communication area and the first end; the high-pressure unit 5 includes a pressure amplification chamber 51, a pressure amplification portion 52, and a fuel removal tank 53; wherein the content of the first and second substances,

the pressure amplification chamber 51 is communicated with the communication areas on the first high-pressure oil pipes 4;

the pressure amplification part 52 comprises a pressurized oil pipe 521, a first piston 522 and a second piston 523, wherein the pressurized oil pipe 521 comprises a first part 5211 and a second part 5212 which are communicated with each other and have the same central line, the inner diameter of the first part 5211 is smaller than that of the second part 5212, one end of the first part 5211, which is far away from the second part 5212, is communicated with the pressure amplification chamber 51, the first piston 522 is positioned in the second part 5212 and is in sealing fit with the inner wall of the second part 5212, one end of the second piston 523 is in sealing fit with the inner wall of the first part 5211, and the other end of the second piston 523 is abutted against the first piston 522;

the oil removal tank 53 is communicated with a chamber of the second part 5212 between the first piston 522 and the first part 5211, the chambers of the oil removal tank 53 and the second part 5212 between the first piston 522 and one end far away from the first part 5211 are connected with the same high-pressure oil supply pipeline, an oil discharge hole 531 is formed in the oil removal tank 53, and a second control valve 532 for controlling oil discharge is arranged at the oil discharge hole 531.

In the fuel system provided by the embodiment of the invention, the fuel in the fuel tank 1 can be pressurized by the high-pressure fuel pump 2 and then supplied to the common rail pipe 3 for pressure stabilization, and then supplied to the fuel injector 62 for injection through the first high-pressure fuel pipe 4, the high-pressure unit 5 can pressurize the high-pressure fuel pressurized by the high-pressure fuel pump 2 again, wherein the high-pressure unit 5 comprises a pressure amplifying chamber 51, a pressure amplifying part 52 and a fuel removing tank 53, the pressure amplifying part 52 comprises a pressurized-oil pipe 521, a first piston 522 and a second piston 523, the first piston 522 divides a second part 5212 of the pressurized-oil pipe 521 into a first chamber A between the first piston 522 and the first part 5211 and a second chamber B between the first piston 522 and one end of the second part 5212 far away from the first part 5211, the fuel removing tank 53 is communicated with the first chamber A, and the fuel removing tank 53 is connected with the same high-pressure fuel supply pipeline as the second chamber B, when the high-pressure unit 5 does not pressurize the fuel, the pressure amplification chamber 51, the first chamber a and the second chamber B are filled with the fuel, the pressure of the pressure amplification chamber 51, the pressure of the first chamber a and the pressure of the second chamber B are equal, the pressure of two sides of the first piston 522 are balanced, when the high-pressure unit 5 is required to pressurize the fuel, the second control valve 532 can be opened, the fuel in the second chamber B flows out from the oil discharge port 531, the pressure balance of two sides of the first piston 522 is destroyed, the first piston 522 can drive the second piston 523 to move to pressurize the fuel in the pressure amplification chamber 51, the pressure amplification factor of the fuel is the ratio of the cross-sectional area of the first piston 522 to the cross-sectional area of the second piston 523, and in order to prevent the fuel from flowing back after being pressurized by the high-pressure unit 5, the first high-pressure fuel pipe 4 is provided with the check valve. In the fuel system, the fuel oil which is delivered to the plurality of fuel injectors 62 for injection is pressurized again through the high-pressure unit 5 and the second control valve 532, so that the variable fuel injection rule when the plurality of fuel injectors 62 inject the fuel oil can be realized, the control operation is simple, the structure is simple, and the equipment cost can be saved.

In the fuel system provided by the above-mentioned embodiment of the invention, a return spring is further disposed between one end of the second portion 5212, which is close to the first portion 5211, in the second portion 5212 and the first piston 522, and the return spring can restore the first piston 522 to a pressure-balanced position after the high-pressure unit 5 re-pressurizes the fuel.

In the fuel system provided by the above embodiment of the present invention, the communication areas on the plurality of first high-pressure fuel pipes 4 are all communicated, and the pressure amplification chamber 51 is better communicated with the communication areas of the first high-pressure fuel pipes 4.

Specifically, the fuel system may further include a second high-pressure fuel pipe 7, the second high-pressure fuel pipe 7 is communicated with the communication areas of the first high-pressure fuel pipes 4, the pressure amplification chamber 51 is communicated with the communication areas of the first high-pressure fuel pipes 4 through the second high-pressure fuel pipe 7, the pressure amplification chamber 51 is communicated with the communication areas of the first high-pressure fuel pipes 4, and the high-pressure unit 5 may pressurize the fuel delivered to the plurality of fuel injectors 62 again.

In another embodiment, the plurality of first high-pressure oil pipes 4 may not be communicated with each other, and the pressure amplification chamber 51 may be communicated with the plurality of first high-pressure oil pipes 4, respectively. The connection structure between the plurality of first high-pressure oil pipes 4 is not limited herein and may be set according to actual conditions.

In the fuel system according to the above-mentioned embodiment of the present invention, the deoiling tank 53 is communicated with the common rail pipe 3, the chamber of the second portion 5212 between the first piston 522 and the end far from the first portion 5211 is communicated with the common rail pipe 3, that is, the deoiling tank 53 is communicated with the common rail pipe 3, and the second chamber B in the second portion 5212 is also communicated with the common rail pipe 3, so that the deoiling tank 53 and the second chamber B are connected to the same high pressure supply line, and when the high pressure unit 5 is not pressurized, the fuel from the common rail pipe 3 fills the first chamber a, the second chamber B and the pressure amplifying chamber 51 respectively. Specifically, the first chamber a communicates with the deoiling tank 53 through a high-pressure oil pipe, and the deoiling tank 53 and the second chamber B also communicate with the common rail pipe 3 through a high-pressure oil pipe.

The above-described embodiments of the invention provide a fuel system in which each first high pressure fuel line 4 may be connected to a fuel injector 62 via a high pressure connector 42.

Specifically, the first high-pressure oil pipe 4 and the high-pressure connector 42 may be integrally connected. Alternatively, the first high pressure oil line 4 and the high pressure connector 42 may be a split connection.

In the above-described embodiment of the invention, specifically, the first control valve and the second control valve 532 may be solenoid valves. In another embodiment, the first and second control valves 532 may be different types of valves.

The fuel system provided by the embodiment of the invention further comprises a control unit, wherein the control unit is in signal connection with the first control valve and the second control valve 532, and the control unit is used for controlling the working states of the plurality of first control valves and the second control valves 532 so as to enable the fuel injection rule of the fuel injector to be variable.

Specifically, the control unit may be an ECU control module, and the ECU control module controls the first control valve and the second control valve 532 to control fuel injection from the fuel injector and pressurization of the high pressure module.

Based on the same inventive concept, the invention also provides a control method of the fuel system, as shown in fig. 2, the specific steps may include:

s201: determining the working condition of the engine according to the rotating speed data and the load data of the engine;

s202: and controlling the working states of the plurality of first control valves and the plurality of second control valves according to the working condition of the engine so as to enable the oil injection rule of the oil injector to be variable.

According to the control method of the fuel system, firstly, the working condition of the engine is determined according to the rotating speed data and the load data of the engine, then the working states of the first control valves and the second control valves are controlled according to the working condition of the engine, so that the fuel injection rule of the fuel injectors is variable, the pressure change of the fuel injection of the fuel injectors can be adjusted by only controlling the second control valves, the fuel injectors can realize the variable fuel injection rule, the control steps are simple, and the working efficiency of the fuel system is improved.

In one specific embodiment, the controlling the operating states of the first control valve and the second control valve according to the operating condition of the engine comprises:

for a multi-cylinder engine, an oil sprayer is arranged in each cylinder of the engine, when the engine is detected to be in a starting working condition or a regeneration working condition, a part of first control valves in the first control valves are controlled to be opened in sequence according to a first preset sequence, so that a part of oil sprayers spray fuel, and a part of oil sprayers do not spray fuel, an asymmetric oil spraying strategy of the oil sprayers is realized, and the exhaust temperature, the starting performance of the engine and the regeneration efficiency can be improved. Among the plurality of first control valves, the first control valve to be opened and the first control valve to be closed may be selected according to actual engine body information of the engine, and the first preset sequence may be set according to the actual engine body information of the engine, which is not limited herein. Whether the high-pressure unit is pressurized or not when the engine is in the starting condition and the regeneration condition also needs to be set according to the condition, namely whether the second control valve is opened or not is set according to the actual requirement.

Specifically, when the engine is in a normal operation condition, all the first control valves in the plurality of first control valves are controlled to be opened in sequence according to a second preset sequence, so that all the oil injectors inject oil according to the second preset sequence, and a conventional oil injection strategy of the oil injectors is realized.

According to the control method of the fuel system, the engine is in a normal operation working condition and can have different rotating speeds and loads, a plurality of working conditions can be divided according to the rotating speeds from low to high and the loads from large to small, specific numerical values of the rotating speeds and the loads can have different numerical values according to different engines, and the control strategies of the engine under different working conditions are not influenced by the division of the numerical value regions. Specifically, when the engine normally operates, the conditions of low rotation speed and small load, medium and low rotation speed and medium and large load, medium and low rotation speed and large load, high rotation speed and the like can be classified according to the increase of the rotation speed and the load.

In a specific embodiment, when the engine is in a normal operating condition, controlling all the first control valves in the plurality of first control valves to open sequentially according to a second preset sequence may specifically include the following conditions:

specifically, in the running process of the engine, when the working condition that the engine is at a low rotating speed and a small load is detected, the engine is at a low rotating speed, the load of the engine is low, the control valves can be controlled to be opened in sequence at the moment, the second control valve is not opened, the high-pressure unit is not pressurized, the fuel oil is at the oil pressure after being pressurized by the high-pressure oil pump, secondary pressurization is not carried out, and the normal running of the engine can be ensured.

specifically, when the rotation speed and the load of the engine are detected to be increased to a medium-low rotation speed and a large load state in the running process of the engine, at the moment, the rotation speed of the engine is increased, the load is increased, the second control valve is controlled to be opened firstly, so that the pressurizing unit pressurizes fuel for the second time, then the first control valve is controlled to be opened, the injector injects the fuel subjected to the secondary pressurization, the fuel injector injects the fuel according to a slope type fuel injection rule, and the power output of the engine is stable.

specifically, in the running process of the engine, when the load of the engine is detected to be continuously increased to a large load state, namely the engine is in a medium-low rotating speed and large load working condition, more combustion needs to be provided to ensure that the engine has enough output power, the first control valve can be controlled to be opened firstly, the fuel injector injects the fuel pressurized by the high-pressure fuel pump firstly, the second control valve is controlled to be opened while the fuel is output, the fuel is pressurized again, the fuel injector injects fuel according to a boot-shaped fuel injection rule, the fact that the oil pressure in the fuel injector does not change suddenly along with the injection pressure of the fuel is ensured, the fuel pressure is stable, the engine meets the power supply requirement, and the fuel consumption can be reduced.

Specifically, when the rotating speed of the engine is detected to be increased to a high rotating speed in the running process of the engine, namely the engine is in a high rotating speed working condition, the second control valve is controlled to be opened firstly, the high-pressure unit pressurizes fuel again firstly, the first control valve is opened later, and the fuel injector injects the fuel subjected to secondary pressurization, so that the fuel injector can inject fuel according to a rectangular fuel injection rule, the fuel rate sprayed by the fuel injector is improved, the fuel injector is matched with the intake and exhaust of the engine at the high rotating speed, the fuel is ensured to be fully combusted, and the emission is reduced.

In the control method of the fuel system, to realize an ideal fuel injection rule, a control instruction of the first control valve and a control instruction of the second control valve need to be accurately controlled, specifically, a control flow of the fuel system can control the fuel injection state of the fuel injector and the pressurization state of the high-pressure unit by controlling the working states of the first control valve and the second control valve as shown in fig. 3, so that the fuel injection rule of the fuel injector can be changed, and the effects of improving the exhaust temperature, reducing the emission and reducing the fuel consumption can be realized according to different working conditions of an engine.

It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A fuel system is characterized by comprising a fuel tank, a high-pressure oil pump, a common rail pipe, a plurality of first high-pressure oil pipes, a high-pressure unit and an engine; the fuel tank is connected with the common rail pipe through the high-pressure oil pump, a plurality of cylinders are arranged in a body of the engine, an oil injector is arranged in each cylinder, a first control valve used for controlling fuel injection is arranged on each oil injector, the first end of a first high-pressure oil pipe is connected with the common rail pipe, the second end of the first high-pressure oil pipe is connected with the oil injectors in a one-to-one correspondence mode, a communication area is arranged between the first end and the second end, and a one-way valve with an opening facing the second end is arranged between the communication area and the first end; the high-pressure unit comprises a pressure amplifying chamber, a pressure amplifying part and an oil removing tank; wherein the content of the first and second substances,

2. The fuel system as recited in claim 1, wherein a return spring is disposed between an end of the second portion adjacent the first portion and the first piston.

3. The fuel system as recited in claim 1, further comprising a second high pressure fuel line communicating with a communication area of each of said first high pressure fuel lines, said pressure amplifying chamber communicating with a communication area on each of said first high pressure fuel lines through said second high pressure fuel line.

4. The fuel system as recited in claim 1, wherein said defueling tank is in communication with said common rail, and a chamber of said second portion between said first piston and an end remote from said first portion is in communication with said common rail.

5. The fuel system as recited in claim 1, wherein each of said first high pressure fuel lines is connected to said fuel injector by a high pressure connector.

6. The fuel system as recited in claim 5, wherein the first high pressure fuel line is integrally connected with the high pressure connector.

7. The fuel system as recited in claim 1, further comprising a control unit in signal communication with said first and second control valves, said control unit being configured to control the operating states of the plurality of first and second control valves such that the injection schedule of the injector is variable.

8. A control method of a fuel system according to any one of claims 1-7, comprising:

9. The control method according to claim 8, wherein the controlling the operating states of the first control valve and the second control valve according to the operating condition of the engine includes:

10. The control method of claim 9, wherein controlling all of the plurality of first control valves to open sequentially in a second predetermined sequence when the engine is in a normal operating condition comprises: