WO2010060378A1

WO2010060378A1 - Fuel control system for alcohol and gasoline dual-fuel engine and control method thereof

Info

Publication number: WO2010060378A1
Application number: PCT/CN2009/075130
Authority: WO
Inventors: 王永军; 张志福; 黄波; 董宏伟; 徐伏韫
Original assignee: 奇瑞汽车股份有限公司
Priority date: 2008-11-27
Filing date: 2009-11-25
Publication date: 2010-06-03
Also published as: CN101418726A; CN101418726B

Abstract

A fuel control system for alcohol and gasoline dual-fuel engine and a control method thereof are provided. The control system includes a main fuel supply system and an auxiliary fuel supply system. The main fuel supply system includes a main fuel tank (6), a main fuel pump (4), a main fuel pipeline (10), a fuel rail (3) and a fuel injector (1) which are communicated in order. The auxiliary fuel supply system includes an auxiliary fuel tank (17), an auxiliary fuel pump (15), an auxiliary fuel pipeline (14) and the fuel rail (3) and the fuel injector (1) shared with the main fuel supply system which are communicated in order. The control method adopts an automobile engine control unit to automatically switch the main fuel supply system and the auxiliary fuel supply system of the control system so as to complete the automatic control to the fuel of alcohol and gasoline dual-fuel engine.

Description

Alcohol and gasoline dual fuel engine fuel control system and control method thereof

Technical field

The present invention relates to the field of fuel control for alcohol and gasoline dual fuel automobile engines, and more particularly to an alcohol and gasoline dual fuel engine fuel control system and control method. Background technique

The development of the automotive industry faces two major problems: oil shortage and environmental pollution. One of the more promising methods to solve these two problems is to use alternative fuels. Alcohol fuels and CNG (compressed natural gas) are considered to be able to Two more promising alternative fuels that are used in large quantities. Foreign countries have studied various alternative fuels after the oil crisis. The US Energy Research and Development Agency believes that: "Methanol is the most promising alternative fuel, which can be made from coal. The process has reached mass production and is suitable for internal combustion engines. It is a clean fuel. " . The "Motor's Future", jointly researched by the United States, Japan, Britain, Germany, France, Italy and the Swedish automotive industry, believes that: "Methanol is a promising car fuel, it is easier to control pollution, and coal can be used as a raw material." At the same time, there are a large number of ethanol vehicles in the world, and many ethanol vehicles are in operation in Brazil, the United States and the European Union. Pure alcohols are used as fuels for automobiles. The biggest technical obstacle in actual use is the cold start problem when burning pure alcohols. The cold start is difficult to evaporate the fuel at low temperatures, causing the engine to not start easily. Gasoline engines have been used for many years and are now in good condition. Compared with gasoline, the initial boiling point of alcohol is low, and the latent heat of vaporization is several times higher than that of gasoline. For example, for methanol saturated steam pressure is only about one-half of gasoline, and fuel flow is about gasoline when engine power is constant. Double. The latent heat of evaporation of ethanol is more than twice that of gasoline. Due to the large latent heat of evaporation, the amount of heat absorbed during evaporation is high, which causes the temperature of the intake pipe of the engine to drop sharply, which worsens the evaporation conditions of the intake air. Therefore, only a small amount is used during cold start. Ethanol can evaporate. If the concentration of combustible mixture formed by evaporation does not reach the lower limit of ignition concentration, the mixture cannot be ignited and the cold start of the engine is difficult. These reasons make it difficult to evaporate the methanol/ethanol fuel and do not form a proper proportion of the mixture during cold start. Therefore, an engine using an alcohol fuel is more difficult than a cold start using a gasoline engine, and burning a gasoline using a gasoline engine does not give a good effect.

Therefore, the existing engine uses methanol or ethanol as fuel, and the main problem to be solved is to solve the problem of cold start of the alcohol engine. Practice has proved that increasing the intake air temperature is the most effective way to promote fuel gasification. Currently, there is a method of preheating the part of the intake port by using an electric heating device to assist the evaporation of the fuel. This method is helpful for the cold start of the engine, but does not shorten the warm-up time. Moreover, the energy of electric heating comes from the car battery. For a pure methanol engine, the energy provided by the battery is far from meeting the requirement of starting the motor and heating the mixture at the cold start. In addition, the current use of gasoline-based gasoline dual-fuel engines is based on the addition of a gasoline-assisted starter to the original gasoline engine. It is called a gasoline cold start device. This gasoline cold start system is a stand-alone system that works when the engine is cold-started. When the engine is warmed up, it switches to the original fuel supply system. Advantages: It can guarantee the low temperature starting performance of the engine. Disadvantages: Re-development of fuel supply systems, engines and other components is required. The products involve the development of many components, long cycle, high cost, changing the intake port of the engine, reducing the high-speed performance of the engine, and at the same time when the system is switched. Harshness can cause poor driving. Summary of the invention

The primary technical problem to be solved by the present invention is to provide an alcohol and gasoline dual fuel engine fuel control system for the deficiencies of the prior art, by which the alcohol and gasoline dual fuel engines can use the original gasoline engine. Oil system, and do not improve parts of other parts of the engine.

The primary technical problem to be solved by the present invention is achieved by the following technical solutions:

An alcohol and gasoline dual fuel engine fuel control system includes a main fuel supply system provided with a main oil tank, a main oil pump, a main oil pipeline, a fuel rail and a fuel injector, and the main oil pump is installed in the main oil tank and the main oil pipeline and the oil rail And an injector in sequence; further comprising an auxiliary fuel supply system and a three-way valve using a gasoline cold start engine; the auxiliary fuel supply system including a sub tank, a sub-oil pump, a sub-transport, and a shared with the main fuel supply system The oil rail and the injector; the auxiliary oil pump is installed in the auxiliary oil tank and communicates with the auxiliary oil pipeline, and then sequentially communicates with the oil rail and the fuel injector through the three-way valve; the three-way valve The other end is connected to the main oil pipeline.

The invention provides gasoline or alcohol fuel for the engine by using the original fuel supply system as the main fuel supply system on the basis of the original gasoline engine fuel supply system, and there is no change compared with the original gasoline engine when using gasoline as the fuel. Maintain the stability of the original engine structure. An auxiliary fuel supply system for cold start when the main fuel supply system uses alcohol fuel is added, and the auxiliary fuel supply system shares the components of the fuel rail and the injector directly connected to the engine combustion chamber with the main fuel supply system, and ensures The stability of the auxiliary fuel supply system, that is, without the main fuel supply system, the use of the auxiliary fuel supply system itself is a complete gasoline engine system.

A second technical problem to be solved by the present invention is to provide a control method for the above alcohol and gasoline dual fuel engine fuel control system, which is controlled by an engine controller (ECU), in view of the deficiencies of the prior art. Next, automatic control of the engine fuel supply system.

The second technical problem to be solved by the present invention is achieved by the following technical solutions:

An alcohol and gasoline dual fuel engine fuel control method that utilizes an engine controller to detect engine fuel type and monitor engine operating conditions, and automatically engine based on engine selected fuel and monitored engine operating conditions Control, including the following steps:

A. When the car ignition switch is set to "on", the engine controller detects whether the fuel selection switch is in the gasoline position.

Bl. When the result of step A is "Yes", enter the gasoline operation mode.

B2. When the result of step A is "No", the engine controller detects the engine operating condition and determines whether gasoline assisted starting is required.

2 When the result of the judgment in step B2 is "NO", the alcohol fuel operation mode is entered.

B22. When the result of the determination in step B2 is “YES”, the gasoline assist start mode is entered, and the engine controller continues to detect the engine operating condition until the engine operating condition meets the alcohol fuel operating condition, and then proceeds to step B21.

The invention utilizes an engine controller (ECU) to automatically control the engine of the automobile, and only needs to use the main fuel tank to provide a selection signal of the fuel used and use the sensor to sense other signals such as engine operating conditions, such as the water cooling system of the engine. The temperature is measured, and the engine controller (ECU) automatically controls the fuel control system of the engine system. No manual intervention is required, the method is simple, and control is in place.

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. DRAWINGS

Figure 1 is a block diagram showing the fuel supply of the engine control system of the present invention;

2 is a flow chart of a control method of the present invention.

In the picture:

1. Injector, 2. Pressure relief valve, 3. Oil rail, 4. Main oil pump, 5. Sub tank fuel return pipe,

6, the main fuel tank, 7, three-way valve, 8, the auxiliary oil pipe check valve, 9, the main oil pipe check valve,

10, the main oil pipeline, 11, the main fuel tank fuel filter, 12, the main fuel pipeline three-way valve,

13, the main fuel tank return pipe, 14, the auxiliary oil pipeline, 15, the auxiliary oil pump,

16. Sub-tank fuel filter, 17. Sub-tank. detailed description

As shown in Fig. 1, an alcohol and gasoline dual fuel engine fuel control system, the fuel control system includes two fuel supply passages, a main fuel supply system and an auxiliary fuel supply system, respectively. The fuel control system uses gasoline as a fuel to supply gasoline to the engine combustion chamber using the main fuel supply system, and the auxiliary fuel supply system does not operate. When using alcohol fuels, it is only necessary to use an auxiliary fuel supply system to provide engine combustion chambers during cold start of the vehicle. Gasoline, when the temperature meets the operating conditions of the alcohol fuel, switches to the main fuel supply system to supply alcohol fuel to the engine combustion chamber, and the auxiliary fuel supply system does not work. When the vehicle is hot-started, if the temperature is in compliance with the alcohol fuel operating conditions, the main fuel supply system also supplies the alcohol combustion fuel to the engine combustion chamber, at which time the auxiliary fuel supply system does not operate. In FIG. 1: The main fuel supply system includes a main oil tank 6, a main oil pump 4, a main oil feed pipe 10, a fuel rail 3, and a fuel injector 1. The main fuel tank 6 has a fuel selection switch, and its fuel selection signal is output to the engine controller. The auxiliary fuel supply system includes a sub tank, a sub-oil pump 15, a sub-oil pipe 14, a fuel rail 3, and an injector 1. The oil rail 3 and the injector 1 are shared by two systems. When the main oil pipe 10 and the auxiliary oil pipe 14 are injected into the oil rail 3 and the injector 1, a three-way valve 7 is used. One input end of the three-way valve 7 is connected to the main oil delivery pipe 10, the other input end is connected to the auxiliary oil delivery pipe 14, and the output end is connected to the oil supply rail 3. The main tank fuel filter 11 in the main tank 6 and the sub tank fuel filter 16 in the sub tank 17 are installed at the outlets of the main oil pump 4 and the sub oil pump 15, respectively. In addition, the fuel control system further includes a sub tank returning system, and the sub tank returning system includes a sub tank return pipe 5 connected to the sub tank 17 and the oil rail 3, and a sub tank installed in the oil rail 3 The pressure relief valve 2 between the oil return pipes 5, in this embodiment, the pressure relief valve 2 is a mechanical pressure relief valve, when the oil pipe cleaning of the oil pipe is required, the mechanical pressure relief valve 2 is opened, and the engine controller (ECU) The injector 1 does not operate under the control, and the fuel in the fuel rail 3 is returned to the sub tank 17 through the sub tank return pipe 5. The fuel control system further includes a main tank returning system, and the main tank returning system includes a main oil pipe three-way valve 12 disposed at an outlet of the main fuel tank fuel filter 11 and connected by the main oil pipe three-way valve 12 In the main tank 6 and the main tank return pipe 13 of the main tank fuel filter 11, the other end of the main oil pipe three-way valve 12 is in communication with the main oil pipe 10. When the fuel drawn by the main oil pump 4 exceeds the flow rate of the main oil feed pipe 10, part of the fuel flows back to the main oil tank return pipe 13 through the main oil pipe three-way valve 12 after the main fuel tank fuel filter 11, and enters the main oil tank 6. In order to ensure isolation between the main and auxiliary fuel supply systems, a main oil feed pipe check valve 9 and a secondary oil feed pipe check valve 8 are installed in the main oil feed pipe 10 and the auxiliary oil feed pipe 14, respectively. The above-described main and auxiliary oil pumps and fuel injectors 1 are all controlled by an engine controller (ECU).

As can be seen from Fig. 1, in the fuel control system of the present embodiment, the fuel has the following circulation paths:

1. Main fuel circulation path: In the main fuel tank 6, the engine controller (ECU) controls the main oil pump 4 to operate, the gasoline passes through the main fuel tank fuel filter 11, the main oil pipeline three-way valve 12, the main oil pipeline 10, and the main oil pipeline one-way. The valve 9, the three-way valve 7, and the oil rail 3 are supplied with fuel to the engine combustion chamber through the injector 1. This is the main flow path for fuel, and is the fuel flow path when the engine uses gasoline and when alcohol fuel is used normally.

2. Main fuel recovery path: In the main fuel tank 6, the engine controller (ECU) controls the main oil pump 4 to operate. After the gasoline passes through the main fuel tank fuel filter 11 and the main oil pipeline three-way valve 12, the excess fuel passes through the main oil pipeline 3 The other output of the valve 12 is returned from the main tank return line 13 to the main tank 6. This path is the path to recover excess fuel while the engine is operating normally. 3. Gasoline assisted starting fuel circulation path: In the auxiliary fuel tank 17, the engine controller (ECU) controls the auxiliary oil pump 15 to operate, the gasoline passes through the auxiliary fuel tank fuel filter 16, the auxiliary oil delivery pipe 14, the auxiliary oil pipeline check valve 8, and the three-way valve 7 The fuel rail 3 supplies fuel to the engine combustion chamber through the injector 1. This fuel circulation path is not much different from the gasoline passage of a general gasoline engine. When the engine is cold-started, the engine is started by the gasoline in the auxiliary fuel tank 17, and when the engine operating condition reaches the working requirement of the alcohol fuel, the main fuel circulation path is switched. fuel.

4. Oil line cleaning channel: In the auxiliary fuel tank 17, the engine controller (ECU) controls the auxiliary oil pump 15 to operate, the gasoline passes through the auxiliary fuel tank fuel filter 16, the auxiliary oil delivery pipe 14, the auxiliary oil pipeline check valve 8, the three-way valve 7, the oil The rail 3 is returned to the sub tank 17 through the mechanical pressure relief valve 2 and the auxiliary tank return line 5. Since the alcohol fuel is in the main tank 6, some alcohol fuel remains in the rail before the cold start, and it needs to be cleaned. Therefore, it takes 2 to 10 seconds to remain in the cold start before the cold start. The alcohol fuel in the oil rail is recovered into the auxiliary tank 17.

As shown in FIG. 2, the control method of the above alcohol and gasoline dual fuel engine fuel control system comprises the following steps: A. When the vehicle ignition switch is set to "on", the engine controller detects whether the fuel selection switch is in the gasoline position;

Bl, when the result of step A is "yes", enters the gasoline operation mode; at this time, the engine controller (ECU) controls the main oil pump 4 to operate, the gasoline passes through the main fuel tank fuel filter 11, the main oil pipeline three-way valve 12, The main oil feed pipe 10, the main oil feed pipe check valve 9, the three-way valve 7, and the oil rail 3 supply fuel to the engine combustion chamber through the injector 1 to complete automatic control of the fuel supply system.

B2. When the result of step A is "NO", the engine controller detects the engine operating condition and determines whether a gasoline assisted starting is required; where the engine controller mainly determines whether gasoline is required according to the water temperature and the intake air temperature of the engine cooling water. Auxiliary start.

B21. When the result of the determination in step B2 is "NO", the alcohol fuel operation mode is entered; the engine controller (ECU) controls the operation of the main oil pump 4, the alcohol fuel passes through the main fuel tank fuel filter 11, and the main oil pipeline three-way valve 12. The main oil pipeline 10, the main oil pipeline check valve 9, the three-way valve 7, and the oil rail 3 supply fuel to the engine combustion chamber through the injector 1 to complete automatic control of the fuel supply system.

B22. When the result of the determination in step B2 is “YES”, the gasoline assist start mode is entered, and the engine controller continues to detect the engine operating condition. Here, the engine controller mainly determines whether it needs to be performed according to the water temperature temperature and the intake air temperature of the engine cooling water. Gasoline assisted start. Until the engine operating conditions meet the alcohol fuel operating conditions, go to step B21.

In the above gasoline assisted starting mode, the following steps B221 are performed for the first 2 to 10 seconds, and then step B222 is performed: B221, the engine controller controls the auxiliary oil pump 15 to operate, the gasoline passes through the auxiliary fuel tank filter 16, the auxiliary oil pipeline 14, and the auxiliary oil pipeline Returning the auxiliary oil to the valve 8, the three-way valve 7, the oil rail 3 through the mechanical pressure relief valve 2, the auxiliary fuel tank return pipe 5 Box 17. This step completes the cleaning of the oil circuit, and the oil circuit cleaning is completed to enter the gasoline auxiliary start.

B222. The engine controller controls the auxiliary oil pump 15 to operate. The gasoline passes through the auxiliary fuel tank fuel filter 16, the auxiliary oil delivery pipe 14, the auxiliary oil supply pipe check valve 8, the three-way valve 7, and the oil rail 3 to supply fuel to the engine combustion chamber through the fuel injector 1. . This step completes the auxiliary start-up process of the gasoline to the engine.

Claims

Claim

1. An alcohol and gasoline dual fuel engine fuel control system comprising a main unit provided with a main tank (6), a main oil pump (4), a main oil pipeline (10), a fuel rail (3) and an injector (1) Fuel supply system, main oil pump (4) installed in main tank

(6) Internally connected with the main oil pipeline (10), the oil rail (3) and the fuel injector (1); characterized in that: an auxiliary fuel supply system and a three-way valve (7) using a cold start engine of the gasoline; The auxiliary fuel supply system includes a sub tank (17), a sub-oil pump (15), a sub-oil pipe (14), and the oil rail (3) and the injector (1) shared with the main fuel supply system; The auxiliary oil pump (15) is installed in the auxiliary oil tank (17) to communicate with the auxiliary oil pipeline (14), and then sequentially communicates with the oil rail (3) and the fuel injector (1) through the three-way valve (7). The three-way valve (7) is terminated at the other end of the main oil pipe (10).

2. The alcohol and gasoline dual fuel engine fuel control system according to claim 1, further comprising: a main tank fuel filter (11) and a sub tank fuel filter (16), respectively installed in said At the outlet of the main oil pump (4) and the auxiliary oil pump (15).

3. The alcohol and gasoline dual fuel engine fuel control system according to claim 2, further comprising: a sub tank returning system, said sub tank returning system comprising said auxiliary tank (17) and said The auxiliary tank return line (5) of the oil rail (3) and the pressure relief valve (2) installed between the oil rail (3) and the auxiliary tank return line (5).

4. The alcohol and gasoline dual fuel engine fuel control system of claim 3, further comprising: a main tank return system, said main tank return system comprising fuel filter disposed in said main tank The main oil pipe three-way valve (12) at the outlet of the cleaner (11) and the main tank return pipe of the main fuel tank (6) and the main fuel tank fuel filter (11) connected by the main oil pipe three-way valve (12) (13), the other output end of the main oil pipe three-way valve (12) is in communication with the main oil pipe (10).

5. The alcohol and gasoline dual fuel engine fuel control system according to claim 4, further comprising: a main oil feed pipe check valve (9) and a secondary oil feed pipe check valve (8), respectively installed in said The main oil pipe (10) and the auxiliary oil pipe (14).

The alcohol and gasoline dual fuel engine fuel control system according to any one of claims 1 to 5, characterized in that: the main tank has a fuel selection switch, and the fuel selection signal is outputted to the engine control Device.

7. The method for controlling an alcohol and gasoline dual fuel engine fuel control system according to any one of claims 1 to 5, using an engine controller to detect an engine fuel type and monitoring engine operating conditions, fuel and monitoring selected according to the engine The engine operating conditions to the engine are automatically controlled, including the following steps:

A. When the car ignition switch is set to "on", the engine controller detects whether the fuel selection switch is in the gasoline position;

Bl, when the result of step A is "yes", enter the gasoline running mode;

B2. When the result of step A is "No", the engine controller detects the engine operating condition and determines whether gasoline assisted starting is required;

2 When the result of step B2 is "NO", enter the alcohol fuel operation mode;

8. The control method for an alcohol and gasoline dual fuel engine fuel control system according to claim 7, wherein: in the step B1, when entering the gasoline operation mode, the engine controller controls the main oil pump ( 4) Operation, gasoline passes through main fuel tank fuel filter (11), main oil pipeline three-way valve (12), main oil pipeline (10), main oil pipeline check valve (9), three-way valve (7), oil rail ( 3) Fuel is supplied to the engine combustion chamber through the injector (1).

9. The control method for an alcohol and gasoline dual fuel engine fuel control system according to claim 7, wherein in the step B21, when entering the alcohol fuel operation mode, the engine controller controls the main The oil pump (4) is operated, the alcohol fuel passes through the main fuel tank fuel filter (11), the main oil pipeline three-way valve (12), the main oil pipeline (10), the main oil pipeline check valve (9), the three-way valve (7) The fuel rail (3) supplies fuel to the engine combustion chamber through the injector (1).

10. The control method for an alcohol and gasoline dual fuel engine fuel control system according to claim 7, wherein: in the step B22, when the gasoline assisted start mode is entered, at the beginning of 2-10 seconds When the following step B221 is performed, then proceed to step B222:

B221, the engine controller controls the auxiliary oil pump (15) to operate, and the gasoline passes through the auxiliary fuel tank fuel filter (16), the auxiliary oil pipeline (14), the auxiliary oil pipeline check valve (8), the three-way valve (7), the oil rail (3) ) through the pressure relief valve (2), the auxiliary tank back The oil pipe (5) returns to the auxiliary fuel tank (17);

B222, the engine controller controls the auxiliary oil pump (15) to operate, the gasoline passes through the auxiliary fuel tank fuel filter (16), the auxiliary oil pipeline (14), the auxiliary oil pipeline check valve (8), the three-way valve (7), the oil rail (3) ) Fuel is supplied to the engine combustion chamber through the injector (1).