Methanol and diesel dual-fuel engine system and control method

Abstract

The invention discloses a control system of a methanol and diesel dual-fuel engine, relates to the technical field of dual-fuel engines, and solves the technical problems of non-uniform fuel mixing, insufficient combustion, low methanol substitution rate and high formaldehyde emission of the existing methanol and diesel dual-fuel system. The system comprises a diesel supply unit, a diesel vaporization unit, a diesel collection unit, a methanol supply unit, a turbocharger and a catalytic reduction postprocessor, a diesel oil output end of the diesel oil supply unit is connected with a diesel oil input end of the diesel oil vaporization unit, a diesel oil output end of the diesel oil vaporization unit is respectively connected with an air inlet pipeline of an engine and an input end of the diesel oil collection unit, and a diesel oil vaporization output end of the diesel oil collection unit is connected with the air inlet pipeline of the engine. The invention further discloses a control method of the methanol and diesel dual-fuel engine. According to the invention, the pollutant emission level is greatly reduced, and a critical path is provided for the internal combustion engine to realize a carbon reduction target and efficient and clean combustion.

Description

Technical Field

[0001] The present invention relates to the technical field of dual-fuel engines, and more specifically, to a methanol-diesel dual-fuel engine system and a control method. Background Art

[0002] As the global energy crisis and environmental problems become increasingly severe, energy conservation and emission reduction have become an important direction for the development of the automobile industry. Although traditional diesel engines have high thermal efficiency and good economy, their pollution emissions cannot be ignored. Methanol, as a renewable clean fuel, has the characteristics of high oxygen content, low pollution emissions and a wide range of sources, and is regarded as one of the important options to replace traditional fuel in the future. However, in the existing methanol internal combustion engine technology, the combustion method of a single methanol fuel has problems such as low thermal efficiency and high emission pollution, while the existing methanol-diesel dual-fuel system mostly uses mixed fuel or diesel direct injection to ignite low-pressure multi-point injection of methanol. This method has problems such as uneven mixing, incomplete combustion, low methanol substitution rate, and high formaldehyde emissions. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a methanol-diesel dual-fuel engine system and a control method in view of the deficiencies in the prior art, so as to solve the technical problems of uneven fuel mixing, incomplete combustion, low methanol substitution rate and high formaldehyde emission in the existing methanol-diesel dual-fuel system.

[0004] A methanol-diesel dual-fuel engine control system according to the present invention comprises a diesel supply unit, a diesel vaporization unit, a diesel collection unit, a methanol supply unit, a turbocharger and a catalytic reduction post-processor;

[0005] The diesel output end of the diesel supply unit is connected to the diesel input end of the diesel vaporization unit, the diesel output end of the diesel vaporization unit is respectively connected to the intake pipe of the engine and the input end of the diesel collection unit, the diesel vaporization output end of the diesel collection unit is connected to the intake pipe of the engine, the exhaust gas output end of the engine is respectively connected to the exhaust gas input end of the diesel collection unit, the exhaust gas input end of the turbocharger and the exhaust gas input end of the diesel vaporization unit, the exhaust gas input end of the catalytic reduction after-processor is respectively connected to the exhaust gas input end of the diesel collection unit, the exhaust gas input end of the turbocharger and the exhaust gas input end of the diesel vaporization unit, and the air output end of the turbocharger is respectively connected to the air input end of the diesel vaporization unit and the intake pipe of the engine.

[0006] As a further improvement, the diesel vaporization unit includes a low-pressure diesel fuel injector, and the input end of the low-pressure diesel fuel injector is connected to the diesel fuel output end of the diesel fuel supply unit;

[0007] An electric heating device is installed in the diesel vaporization unit, and the electric heating device is electrically connected to an energy storage battery.

[0008] Furthermore, a first temperature sensor is installed in the diesel vaporization unit, a second temperature sensor is installed in the diesel collection unit, and a third temperature sensor is installed at the exhaust gas output end of the engine.

[0009] Furthermore, a first differential pressure sensor is installed at the exhaust gas input end of the diesel vaporization unit, and a second differential pressure sensor is installed at the exhaust gas input end of the diesel collection unit.

[0010] Furthermore, a first electrically controlled pressure regulating valve is installed at the exhaust gas input end of the diesel vaporization unit, and a second electrically controlled pressure regulating valve is installed at the exhaust gas input end of the diesel collection unit.

[0011] Furthermore, a first pressure stabilizing valve is installed at the diesel output end of the diesel vaporization unit, and an electronically controlled flow control valve is installed at the diesel output end of the diesel collection unit.

[0012] Furthermore, a high-pressure methanol common rail pipe is installed on the engine body, and a high-pressure methanol injector and a preheating plug are installed on the cylinder head of the engine.

[0013] Furthermore, the methanol supply unit includes a methanol fuel tank and a methanol pump, and the output end of the methanol fuel tank is connected to a high-pressure methanol common rail pipe through the methanol pump.

[0014] A control method according to the above-mentioned methanol diesel dual-fuel engine control system, the method is:

[0015] Performing a self-check on the state of the engine, and after completing the self-check on the state of the engine, starting the electric heating device to provide energy for preheating the diesel vaporization unit;

[0016] The temperature of the diesel vaporization unit is obtained by a first temperature sensor. When the temperature of the diesel vaporization unit is greater than or equal to a preset first temperature threshold, the ECU controls the diesel injector to inject fuel and starts the engine to stabilize the engine idle speed.

[0017] Acquiring the water temperature of the engine, when the water temperature is greater than a preset water temperature threshold, the ECU controls the high-pressure methanol injector to inject high-pressure methanol main fuel into the engine cylinder, so that the operation mode of the engine is switched from a pure diesel mode to a dual-fuel mode;

[0018] When the operation mode of the engine is the dual fuel mode, the temperature of the diesel collection unit is obtained by a second temperature sensor, and when the temperature of the diesel collection unit is greater than or equal to a preset second temperature threshold, the first adjustment mechanism is triggered;

[0019] The temperature of the exhaust gas output end of the engine is obtained by a third temperature sensor, and when the temperature of the exhaust gas output end of the engine is greater than or equal to a preset third temperature threshold, the electric heating device is turned off.

[0020] As a further improvement, the first regulating mechanism is that, according to a preset load requirement, the ECU regulates the electronically controlled flow control valve so as to increase the diesel injection amount in the diesel collection unit to a preset diesel injection standard amount.

[0021] Beneficial Effects

[0022] The advantages of the present invention are:

[0023] The present invention is provided with a diesel supply unit, a diesel vaporization unit, a diesel collection unit, a methanol supply unit, a turbocharger and a catalytic reduction post-processor, so as to realize the switching of the engine operation mode. The present invention combines the diesel airway injection and the in-cylinder methanol high-pressure direct injection technology, and integrates the advantages of the two injection methods. Without significantly increasing the complexity of the engine structure, the present invention improves the efficient and stable combustion of the engine at a high methanol substitution rate, and at the same time greatly reduces the pollutant emission level, thus providing a key path for the internal combustion engine to achieve the carbon reduction target and efficient and clean combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the overall structure of the methanol-diesel dual-fuel engine system of the present invention;

[0025] Figure 2 A flow chart of a methanol-diesel dual-fuel engine control method of the present invention;

[0026] Figure 3 Schematic diagram of diesel ratio strategy at different operating loads in the dual fuel mode of the present invention.

[0027] Among them: 1-methanol fuel tank, 2-methanol pump, 3-engine, 4-high-pressure methanol injector, 5-preheat plug, 6-high-pressure methanol common rail pipe, 7-intake pipe, 8-first pressure regulating valve, 9-diesel vaporization unit, 10-first temperature sensor, 11-low-pressure diesel injector, 12-diesel pump, 13-diesel tank, 14-electric heating device, 15-energy storage battery, 16-electronically controlled flow control valve, 17-second temperature sensor, 18-diesel collection unit, 19-first electronically controlled pressure regulating valve, 20-first differential pressure sensor, 21-second differential pressure sensor, 22-second electronically controlled pressure regulating valve, 23-turbocharger, 24-third temperature sensor, 25-catalytic reduction post-processor. DETAILED DESCRIPTION

[0028] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of modifications made by anyone within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0029] See also Figure 1-Figure 3 The present invention provides a methanol-diesel dual-fuel engine control system, the system includes a diesel supply unit, a diesel vaporization unit 9, a diesel collection unit 18, a methanol supply unit, a methanol-diesel dual-fuel engine 3, a turbocharger 23, a catalytic reduction post-processor 25, and an energy storage battery 15.

[0030] The diesel output end of the diesel supply unit is connected to the diesel input end of the diesel vaporization unit 9, the diesel output end of the diesel vaporization unit 9 is respectively connected to the intake pipe 7 of the engine 3 and the input end of the diesel collection unit 18, the diesel vaporization output end of the diesel collection unit 18 is connected to the intake pipe 7 of the engine 9, the exhaust gas output end of the engine 3 is respectively connected to the exhaust gas input end of the diesel collection unit 18, the exhaust gas input end of the turbocharger 23 and the exhaust gas input end of the diesel vaporization unit 9, the exhaust gas input end of the catalytic reduction after-processor 25 is respectively connected to the exhaust gas input end of the diesel collection unit 18, the exhaust gas input end of the turbocharger 23 and the exhaust gas input end of the diesel vaporization unit 9, the air output end of the turbocharger 23 is respectively connected to the air input end of the diesel vaporization unit 9 and the intake pipe 7 of the engine 3, and the output end of the methanol supply unit is connected to the engine 7.

[0031] The diesel supply unit comprises a diesel tank 13 and a diesel pump 12, and the output end of the diesel tank 13 is connected to the low-pressure diesel injector 11 through the diesel pump 12. The diesel supply unit is used to provide diesel for the dual-fuel engine.

[0032] The diesel vaporization unit 9 includes a low-pressure diesel injector 11, the input end of which is connected to the diesel output end of the diesel supply unit. The diesel vaporization unit 9 has the main function of atomizing the diesel into fine droplets so that it can be better mixed with air and burned in the combustion chamber. The working principle of the diesel vaporization unit 9 is to inject the diesel into high-temperature and high-pressure compressed air, and the diesel droplets are heated and atomized during the injection process, thereby accelerating the vaporization process.

[0033] The diesel vaporization unit 9 is provided with an electric heating device 14, which is electrically connected to an energy storage battery 15. The energy storage battery 15 is used to supply power to the electric heating device 14, which is used to provide energy for preheating the diesel vaporization unit 9.

[0034] A first temperature sensor 10 is installed in the diesel vaporization unit 9, and the first temperature sensor 10 is used to obtain the temperature of the diesel vaporization unit 9; a second temperature sensor 17 is installed in the diesel collection unit 18, and the second temperature sensor 17 is used to obtain the temperature of the diesel collection unit 18; a third temperature sensor 24 is installed at the exhaust gas output end of the engine 3, and the third temperature sensor 24 is used to obtain the temperature of the exhaust gas output end of the engine 3.

[0035] The exhaust gas input end of the diesel vaporization unit 9 is equipped with a first differential pressure sensor 20, and the exhaust gas input end of the diesel collection unit 18 is equipped with a second differential pressure sensor 21. The first differential pressure sensor 20 is used to obtain the differential pressure value of the exhaust gas input end of the diesel vaporization unit 9, and the second differential pressure sensor 21 is used to obtain the differential pressure value of the exhaust gas input end of the diesel collection unit 18.

[0036] The exhaust gas input end of the diesel vaporization unit 9 is equipped with a first electrically controlled pressure regulating valve 19, and the exhaust gas input end of the diesel collection unit 9 is equipped with a second electrically controlled pressure regulating valve 22. The first electrically controlled pressure regulating valve 19 can adjust the amount of exhaust gas entering the diesel vaporization unit 9, and the second electrically controlled pressure regulating valve 22 can adjust the amount of exhaust gas entering the diesel collection unit 9.

[0037] The diesel output end of the diesel vaporization unit 9 is equipped with a first pressure stabilizing valve 8, and the diesel output end of the diesel collection unit 18 is equipped with an electronically controlled flow control valve 16. The first pressure stabilizing valve 5 is used to keep the internal pressure of the diesel vaporization unit 9 constant within a certain error range. The electronically controlled flow control valve 16 is used to adjust the flow of vaporized diesel entering the engine 3.

[0038] A high-pressure methanol common rail pipe 6 is installed on the engine body of the engine 3, and a high-pressure methanol injector 4 and a preheat plug 5 are installed on the cylinder head of the engine 3. The high-pressure methanol injector 4 is used to inject high-pressure methanol into each cylinder of the engine 3, and the preheat plug 5 is used to achieve auxiliary ignition of the fuel mixture in each cylinder.

[0039] The methanol supply unit includes a methanol fuel tank 1 and a methanol pump 2. The output end of the methanol fuel tank 1 is connected to a high-pressure methanol common rail pipe 6. The methanol pump 2 is installed between the output end of the methanol fuel tank 1 and the high-pressure methanol common rail pipe 6. The methanol supply unit is used to provide methanol to the engine 3.

[0040] like Figure 2 As shown, a control method according to the above-mentioned methanol diesel dual-fuel engine control system is as follows:

[0041] Before starting the engine 3 , power is turned on first to perform a self-check on the state of the engine 3 . After the self-check on the state of the engine 3 is completed, the energy storage battery 15 supplies power to the electric heating device 14 , and the electric heating device 14 is started to provide energy for preheating the diesel vaporization unit 9 .

[0042] The temperature of the diesel vaporization unit 9 is obtained through the first temperature sensor 10. When the temperature of the diesel vaporization unit 9 is greater than or equal to the preset first temperature threshold, the ECU controls the diesel injector to spray fuel, the engine is ignited and started, and the exhaust gas discharged by the engine 3 enters the diesel vaporization unit 9 and the diesel collection unit 18. The electric heating device 14 continuously provides energy for the diesel vaporization in the diesel vaporization unit 9 to make the engine 3 run stably at idle speed.

[0043] The water temperature of the engine 3 is obtained. When the water temperature is greater than the preset water temperature threshold, the ECU controls the high-pressure methanol injector 6 to inject the high-pressure methanol main fuel into the engine cylinder, so that the operation mode of the engine 3 is switched from the pure diesel mode to the dual-fuel mode. The injected diesel ignites the high-pressure methanol main fuel injected into the cylinder by the high-pressure methanol injector 4, thereby achieving efficient combustion of the engine 3.

[0044] When the operation mode of the engine 3 is the dual fuel mode, the temperature of the diesel collection unit 18 is acquired by the second temperature sensor 17. When the temperature of the diesel collection unit 18 is greater than or equal to a preset second temperature threshold, the first regulation mechanism is triggered.

[0045] The first adjustment mechanism is that, according to the preset load requirement, the ECU adjusts the electronically controlled flow control valve 16 to increase the diesel injection amount in the diesel collection unit 18 to the preset diesel injection standard amount, appropriately reduces the diesel injection amount in the diesel vaporization unit 9 and increases the diesel amount input from the diesel collection unit 18 to the engine intake system, such as Figure 3 As shown, the embodiment of the present invention also provides a diesel ratio strategy optimized for different operating loads in the methanol-diesel dual-fuel mode. To ensure the stable operation of the engine 3 in the dual-fuel mode, the diesel ratio is adjusted according to the load state of the engine: under the preset low-load engine condition, the diesel energy ratio is controlled at 8% to 10%; under the preset medium-load engine condition, the diesel energy ratio is adjusted to 5% to 7%; and under the preset medium-load engine condition, the diesel energy ratio does not exceed 5%. Such a design is intended to optimize the engine efficiency and performance.

[0046] The temperature of the exhaust gas output end of the engine 3 is obtained through the third temperature sensor 24. When the temperature of the exhaust gas output end of the engine 3 is greater than or equal to the preset third temperature threshold, the electric heating device 14 is turned off, and the energy required for diesel vaporization is completely provided by the waste heat of the exhaust gas.

[0047] When the ECU detects that the engine is stopped, the electric heating device 14 is turned off and the engine 3 is shut down.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A methanol diesel dual fuel engine control system, characterized in that: The system comprises a diesel supply unit, a diesel vaporization unit (9), a diesel collection unit (18), a methanol supply unit, a turbocharger (23) and a catalytic reduction post-processor (25); The diesel output end of the diesel supply unit is connected to the diesel input end of the diesel vaporization unit (9), the diesel output end of the diesel vaporization unit (9) is respectively connected to the intake pipe (7) of the engine (3) and the input end of the diesel collection unit (18), the diesel vaporization output end of the diesel collection unit (18) is connected to the intake pipe (7) of the engine (9), the exhaust gas output end of the engine (3) is respectively connected to the exhaust gas input end of the diesel collection unit (18), the exhaust gas output end of the turbocharger (23), and the exhaust gas output end of the turbocharger (23). The exhaust gas input end of the catalytic reduction post-processor (25) is connected to the exhaust gas input end of the diesel collection unit (18), the exhaust gas input end of the turbocharger (23) and the exhaust gas input end of the diesel vaporization unit (9), respectively; the air output end of the turbocharger (23) is connected to the air input end of the diesel vaporization unit (9) and the intake pipe (7) of the engine (3), respectively; and the output end of the methanol supply unit is connected to the engine (3).

2. A methanol diesel dual fuel engine control system according to claim 1, characterized in that: The diesel vaporization unit (9) comprises a low-pressure diesel fuel injector (11), the input end of the low-pressure diesel fuel injector (11) being connected to the diesel fuel output end of the diesel fuel supply unit; An electric heating device (14) is installed in the diesel vaporization unit (9), and the electric heating device (14) is electrically connected to an energy storage battery (15).

3. A methanol diesel dual fuel engine control system according to claim 1, characterized in that: The diesel vaporization unit (9) is equipped with a first temperature sensor (10), the diesel collection unit (18) is equipped with a second temperature sensor (17), and the exhaust gas output end of the engine (3) is equipped with a third temperature sensor (24).

4. A methanol diesel dual fuel engine control system according to claim 1, characterized in that: A first differential pressure sensor (20) is installed at the exhaust gas input end of the diesel vaporization unit (9), and a second differential pressure sensor (21) is installed at the exhaust gas input end of the diesel collection unit (18).

5. A methanol-diesel dual-fuel engine control system according to claim 1, characterized in that: The exhaust gas input end of the diesel vaporization unit (9) is equipped with a first electrically controlled pressure regulating valve (19), and the exhaust gas input end of the diesel collection unit (18) is equipped with a second electrically controlled pressure regulating valve (22).

6. A methanol-diesel dual-fuel engine control system according to claim 1, characterized in that: The diesel output end of the diesel vaporization unit (9) is equipped with a first pressure stabilizing valve (8), and the diesel output end of the diesel collection unit (18) is equipped with an electronically controlled flow control valve (16).

7. A methanol-diesel dual-fuel engine control system according to claim 1, characterized in that: A high-pressure methanol common rail pipe (6) is installed on the engine body of the engine (3), and a high-pressure methanol injector (4) and a preheating plug (5) are installed on the cylinder head of the engine (3).

8. A methanol-diesel dual-fuel engine control system according to claim 7, characterized in that: The methanol supply unit comprises a methanol fuel tank (1) and a methanol pump (2), and the output end of the methanol fuel tank (1) is connected to a high-pressure methanol common rail pipe (6) through the methanol pump (2).

9. A control method for a methanol-diesel dual-fuel engine control system according to any one of claims 1 to 8, characterized in that: The method is, Performing a self-check on the state of the engine (3), and after completing the self-check on the state of the engine (3), starting the electric heating device (14) to provide energy for preheating the diesel vaporization unit (9); The temperature of the diesel vaporization unit (9) is obtained by a first temperature sensor (10); when the temperature of the diesel vaporization unit (9) is greater than or equal to a preset first temperature threshold, the ECU controls the diesel injector to spray fuel and starts the engine (3) to ensure stable idling of the engine; The water temperature of the engine (3) is obtained. When the water temperature is greater than a preset water temperature threshold, the ECU controls the high-pressure methanol injector (6) to inject high-pressure methanol main fuel into the engine cylinder, so that the operation mode of the engine (3) is switched from a pure diesel mode to a dual-fuel mode; When the operation mode of the engine (3) is a dual fuel mode, the temperature of the diesel collection unit (18) is obtained through a second temperature sensor (17), and when the temperature of the diesel collection unit (18) is greater than or equal to a preset second temperature threshold, a first adjustment mechanism is triggered; The temperature of the exhaust gas output end of the engine (3) is obtained through a third temperature sensor (24), and when the temperature of the exhaust gas output end of the engine (3) is greater than or equal to a preset third temperature threshold, the electric heating device (14) is turned off.

10. A methanol-diesel dual-fuel engine control method according to claim 9, characterized in that: The first adjustment mechanism is to adjust the electronically controlled flow control valve (16) according to a preset load requirement so as to increase the diesel injection amount in the diesel collection unit (18) to a preset diesel injection standard amount.

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