System for improving cold start performance of methanol extended-range hybrid power system and control method

Abstract

The invention discloses a control method for improving the cold starting performance of a methanol extended-range hybrid power system, relates to the field of engine control, and solves the technical problem that the existing methanol engine starting mode has limited effects on the thermal atmosphere of methanol atomization, premixing and methanol injection ignition success under the low-temperature condition. The method comprises the steps that an engine starting success condition is set, the real-time environment temperature is obtained, when the real-time environment temperature is larger than the preset first starting temperature, a first starting strategy is adopted to start an engine, and whether the engine is started successfully or not is judged according to the engine starting success condition. The invention further discloses a system for improving the cold start performance of the methanol extended-range hybrid power system. Methanol atomization is promoted, methanol is fully premixed, and the successful thermal atmosphere effect and success rate of a methanol injection point are improved.

Description

Technical Field

[0001] The present invention relates to the field of engine control, and more particularly, to a system and a control method for improving the cold start performance of a methanol range-extended hybrid system. Background Art

[0002] To address global energy and environmental challenges, the internal combustion engine industry is continuously seeking renewable, low-carbon alternative fuels. Methanol, with its broad availability of raw materials, economical production, and lack of carbon-carbon bonds, is a promising alternative fuel. However, due to its high latent heat of vaporization (approximately 2.5 times that of gasoline), methanol engines suffer from poor fuel atomization and difficulty forming a mixture during cold starts. Methanol's characteristics dictate its starting temperature requirements: the engine starts easily at ambient temperatures above 20°C and can barely start at temperatures between 15-20°C. However, starting becomes difficult below 15°C.

[0003] The existing patent with publication number CN111058976A discloses a method for heating the intake air of a methanol vehicle and protecting the fuel pump of a methanol vehicle. Its technical solution is that the air passes through a water heating exchanger after being filtered through the air filter. The water heating exchanger converts heat according to the temperature of the engine coolant and performs preliminary heating of the air. The heat transfer of the water heating exchanger is controlled by a control valve. The heat comes from the natural heat dissipation of the engine, further improving the thermal efficiency utilization rate of the internal combustion engine and realizing low-temperature starting of the methanol vehicle.

[0004] The existing patent with publication number CN106762179B discloses a methanol engine cold start control system and method for vehicles. Its technical solution is to heat the air in the intake manifold and the methanol in the injection assembly through two heating elements. The controller selectively turns on and off the first heating element according to the air temperature, and selectively turns on and off the second heating element according to the methanol fuel temperature. The cold start is achieved by heating to meet the methanol starting requirements.

[0005] However, the above-mentioned existing patented technologies are mainly based on a single auxiliary scheme and an injection scheme, which have limited effects on promoting methanol atomization, sufficient premixing and improving the hot atmosphere for successful methanol injection ignition under low temperature conditions. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology and provide a system and control method for improving the cold start performance of the methanol range-extended hybrid system, so as to solve the technical problem that the existing methanol engine starting method has limited effect on the hot atmosphere for methanol atomization, premixing and successful ignition of methanol injection under low temperature conditions.

[0007] The present invention provides a control method for improving the cold start performance of a methanol range-extended hybrid system. The method comprises setting an engine start success condition, obtaining a real-time ambient temperature, and using a first start strategy to start the engine when the real-time ambient temperature is greater than a preset first start temperature. The method then determines whether the engine has been successfully started based on the engine start success condition.

[0008] When it is determined that the engine startup fails after adopting the first startup strategy, or when the real-time ambient temperature is less than or equal to the first startup temperature and greater than or equal to a preset second startup temperature, adopting the second startup strategy to start the engine, and determining whether the engine startup is successful based on the engine startup success condition;

[0009] When it is determined that the engine start fails after adopting the second start strategy, or the real-time ambient temperature is lower than the second start temperature, a third start strategy is adopted to start the engine, and whether the engine start is successful is determined based on the engine start success condition.

[0010] As a further improvement, the first startup strategy is:

[0011] The engine speed is dragged to a preset first speed by a motor, methanol direct injection into the cylinder is started, and the spark plug is used to ignite.

[0012] Furthermore, the second startup strategy is:

[0013] A continuous heating time is set, and the intake heating grid is started to heat the intake air for the continuous heating time. Then, the engine speed is dragged to a preset first speed by a motor, methanol intake port injection is started, and spark plugs are used to ignite.

[0014] Furthermore, the third startup strategy is:

[0015] Starting an electric heating boiler to electrically heat coolant flowing out of a water outlet of the cylinder head, and then allowing the heated coolant to flow through a methanol filter to heat methanol; obtaining a real-time temperature of the coolant at the water outlet of the cylinder head and a real-time temperature of methanol in the methanol filter; and when the real-time coolant temperature is greater than a preset first coolant temperature threshold and the real-time methanol temperature is greater than a preset first methanol temperature threshold, shutting down the electric heating boiler to terminate boiler heating;

[0016] After the boiler heating is completed, the intake air temperature is obtained, and the intake air is heated for a calibrated intake air heating time according to the intake air temperature;

[0017] When the intake air heating is completed, the ambient temperature is obtained, the speed preset value is calibrated according to the ambient temperature, the engine speed is dragged to the speed preset value by the motor, and the methanol intake port injection is controlled at the same time, and ignited by a spark plug.

[0018] Furthermore, when the third start-up strategy is adopted, if the engine fails to start, the first coolant temperature threshold is increased to a preset second coolant temperature threshold, and the first methanol temperature threshold is increased to a preset second methanol temperature threshold, and the third start-up strategy is started again according to the second coolant temperature threshold and the second methanol temperature threshold to start the engine.

[0019] Furthermore, the conditions for successful engine start include:

[0020] First condition: the engine is in an operational state;

[0021] Second condition: the engine water temperature and the engine oil temperature of the engine are both greater than the preset starting temperature value;

[0022] The third condition is that the difference between the actual engine speed and the preset target idle speed is within a preset speed deviation range;

[0023] Fourth condition: the difference between the actual rail pressure of the engine and the preset target rail pressure is within a preset rail pressure deviation range;

[0024] Fifth condition: the actual throttle opening of the engine is less than a preset percentage of the maximum throttle opening;

[0025] Sixth condition: the gear position of the engine is a preset gear position.

[0026] Furthermore, a switching delay time is set, and when it is determined that the engine is started successfully, the switching delay time starts to count; when the switching delay time ends, the methanol intake port injection is switched to methanol direct injection into the cylinder.

[0027] A system for improving the cold start performance of a methanol range-extended hybrid system, comprising:

[0028] An air intake heating grille is installed in the air intake duct of the engine and is used to heat the air in the air intake duct;

[0029] a methanol fuel tank connected to a methanol filter line with a water jacket;

[0030] an electric heating boiler for heating the coolant in the engine and allowing the heated coolant to flow through a methanol filter with a water jacket to heat the methanol therein;

[0031] a methanol intake duct injection nozzle, which is installed in the intake duct of the engine and is used to inject methanol into the intake duct of the engine;

[0032] a plurality of methanol in-cylinder direct injection nozzles, each mounted on the cylinder head of the engine, for injecting the methanol into the cylinder block of the engine;

[0033] The ECU starts the engine using the above-mentioned control method for improving the cold start performance of the methanol range-extended hybrid system.

[0034] As a further improvement, the system also includes a common rail pipe and an injection pump integrated with an oil pump body, the water outlet of the cylinder head is connected to the input pipeline of the electric heating boiler, the output end of the electric heating boiler is connected to the water jacket input pipeline of the water jacket methanol filter, and the water jacket output end of the water jacket methanol filter is connected to the water inlet pipeline of the cylinder body;

[0035] The methanol fuel tank is connected to the oil inlet pipeline of the oil delivery pump body in the fuel injection pump, the oil outlet end of the fuel injection pump and the oil outlet end of the fuel delivery pump body therein are both connected to the oil inlet pipeline of the common rail pipe, and the input end of the fuel injection pump is connected to the output end pipeline of the fuel delivery pump body in the methanol filter fuel injection pump with a water jacket; the common rail pipe is simultaneously connected to multiple methanol in-cylinder direct injection nozzle pipelines, and the common rail pipe is also connected to the methanol intake duct injection nozzle pipeline.

[0036] Furthermore, the system also includes a power battery and a temperature sensor. The power battery is electrically connected to the power supply end of the electric heating boiler, and the temperature sensor is installed in the pipeline between the cylinder head and the electric heating boiler.

[0037] Beneficial effects

[0038] The advantages of the present invention are:

[0039] The present invention sets engine start-up success conditions, obtains real-time ambient temperature, adopts different start-up strategies according to the real-time ambient temperature to start the engine, and determines whether the engine is started successfully according to the engine start-up success conditions, thereby promoting methanol atomization, achieving sufficient methanol premixing, and improving the thermal atmosphere effect of the successful methanol injection point. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the system structure for improving the cold start performance of the methanol range-extended hybrid system according to the present invention.

[0041] Among them: 1-engine, 2-temperature sensor, 3-intake heating grille, 4-methanol intake injection nozzle, 5-common rail pipe, 6-methanol fuel tank, 7-injection pump, 8-electric heating boiler, 9-power battery, 10-methanol filter, 11-methanol direct injection nozzle, 12-cylinder head, 13-cylinder block. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with the embodiments, but this 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.

[0043] See Figure 1 The present invention provides a control method for improving the cold start performance of a methanol range-extended hybrid system. The method includes setting an engine start success condition and obtaining a real-time ambient temperature. When the real-time ambient temperature is greater than a preset first start temperature, a first start strategy is used to start the engine and whether the engine start is successful is determined based on the engine start success condition.

[0044] When the engine start-up fails after adopting the first start-up strategy, or the real-time ambient temperature is less than or equal to the first start-up temperature and greater than or equal to the preset second start-up temperature, the second start-up strategy is adopted to start the engine and determine whether the engine start-up is successful based on the engine start-up success condition.

[0045] If the engine fails to start after the second starting strategy is used, or the real-time ambient temperature is lower than the second starting temperature, the third starting strategy is used to start the engine and determine whether the engine has started successfully based on the engine start success condition. In this embodiment, the first starting temperature is 15°C and the second starting temperature is 20°C.

[0046] The first startup strategy is,

[0047] The motor is used to increase the speed of the engine 1 to a preset first speed, and methanol direct injection is started, and the spark plug is used to ignite the first speed. The first speed is 130 r / min.

[0048] The second startup strategy is,

[0049] After setting a continuous heating time and activating the intake heating grille 3 to heat the intake air for the continuous heating time, the engine 1 is driven to a preset first speed by the motor, methanol intake port injection is started, and ignition is performed using the spark plug. The continuous heating time is 15 seconds.

[0050] The third startup strategy is,

[0051] The electric heating boiler 8 is started to electrically heat the coolant flowing out of the water outlet of the cylinder head 12. The heated coolant then flows through the methanol filter 10 to heat the methanol. The real-time temperature of the coolant at the water outlet of the cylinder head 12 and the real-time temperature of the methanol in the methanol filter 10 are obtained. When the real-time coolant temperature is greater than a preset first coolant temperature threshold and the real-time methanol temperature is greater than a preset first methanol temperature threshold, the electric heating boiler 8 is turned off to terminate boiler heating. The first coolant temperature threshold is 40°C, and the first methanol temperature threshold is 20°C.

[0052] When the boiler heating is completed, the intake air temperature is obtained, the intake air heating time is calibrated according to the intake air temperature, the intake air heating grille 3 is started and the intake air is heated according to the intake air heating time; when the intake air heating time is finished, the intake air heating grille 3 is closed to end the intake air heating.

[0053] Among them, the calibration of the intake air heating time at different intake air temperatures is: when the intake air temperature is -35℃, the intake air heating time is calibrated to 45s; when the intake air temperature is -20℃, the intake air heating time is calibrated to 30s; when the intake air temperature is -10℃, the intake air heating time is calibrated to 25s; when the intake air temperature is 0℃, the intake air heating time is calibrated to 20s; when the intake air temperature is 15℃, the intake air heating time is calibrated to 15s.

[0054] When the intake air heating is completed, the ambient temperature is obtained, the speed preset value is calibrated according to the ambient temperature, the engine speed is dragged to the speed preset value through the motor, and the methanol intake injection is controlled at the same time, and ignition is carried out by the spark plug.

[0055] Among them, the speed preset values ​​at different temperatures are: when the ambient temperature is -40℃, the calibrated drag speed is 80r / min, when the ambient temperature is -20℃, the calibrated speed preset value is 100r / min, when the ambient temperature is -10℃, the calibrated speed preset value is 120r / min, when the ambient temperature is 0℃, the calibrated speed preset value is 130r / min, and when the ambient temperature is 15℃, the calibrated speed preset value is 130r / min.

[0056] When the third starting strategy is adopted, if the engine fails to start, the first coolant temperature threshold is increased to the preset second coolant temperature threshold, and the first methanol temperature threshold is increased to the preset second methanol temperature threshold, and the third starting strategy is activated again according to the second coolant temperature threshold and the second methanol temperature threshold to start the engine.

[0057] The conditions for successful engine start include:

[0058] First condition: the engine is in an operational state (running state).

[0059] Second condition: The engine water temperature and engine oil temperature are both greater than the preset starting temperature value. The starting temperature value is 40°C.

[0060] The third condition is that the difference between the actual engine speed and the preset target idle speed is within the preset speed deviation range, which is ±5 rpm.

[0061] Fourth condition: The difference between the actual rail pressure of the engine and the preset target rail pressure is within the preset rail pressure deviation range. The rail pressure deviation range is ±10 bar.

[0062] Fifth condition: The actual throttle opening of the engine is less than a preset percentage of the maximum throttle opening. The preset percentage is 10%.

[0063] Sixth condition: The engine is in the preset gear position. The preset gear position is 0.

[0064] When the above six conditions are met at the same time, it is determined that the engine is started successfully and the idle speed is stable.

[0065] Set the switch delay time. When the engine is judged to have started successfully, the switch delay time begins. When the switch delay time expires, methanol intake port injection switches to methanol direct injection. The switch delay time is 10 seconds.

[0066] A system for improving the cold start performance of a methanol range-extended hybrid system, comprising:

[0067] The air intake heating grille 3 is installed in the air intake duct of the engine 1 and is used to heat the air in the air intake duct.

[0068] The methanol filter 10 with a water jacket is installed below the methanol fuel tank 6 and is used to filter impurities in the methanol.

[0069] The electric heating boiler 8 is installed on the vehicle and is used for heating the coolant.

[0070] The temperature sensor 2 is installed at the water outlet of the cylinder head 12 of the engine 1 and is used to obtain the real-time temperature of the coolant and input the real-time temperature of the coolant into the ECU.

[0071] The methanol fuel tank 6 is connected to the methanol filter 10 with a water jacket through a pipeline and is used to store methanol fuel.

[0072] an electric heating boiler 8 for heating the coolant in the engine 1 and allowing the heated coolant to flow through a methanol filter 10 with a water jacket to heat the methanol therein;

[0073] The methanol intake port injection nozzle 4 is installed in the intake port of the engine 1 and is used to inject methanol into the intake port of the engine 1, wherein the intake port injection rail pressure range is set to 300-400 bar.

[0074] A plurality of methanol direct injection nozzles 11 are mounted on a cylinder head 12 of the engine for injecting methanol into a cylinder block 13 of the engine, wherein a direct injection rail pressure is set to 400-1000 bar.

[0075] When the engine is started, the injection timing of the intake port injection is set to BTDC300-200°CA, the injection timing of the direct injection pilot injection is set to BTDC5-4°CA, and the injection timing of the main injection is set to BTDC3.5-3°CA.

[0076] The ECU starts the engine 1 using the above-mentioned control method for improving the cold start performance of the methanol range-extended hybrid system.

[0077] The system also includes a common rail pipe 5 and an injection pump 7 integrated with an oil pump body. The water outlet of the cylinder head 12 is connected to the input pipeline of the electric heating boiler 8, the output end of the electric heating boiler 8 is connected to the water jacket input pipeline of the methanol filter with a water jacket 10, and the water jacket output end of the methanol filter with a water jacket 10 is connected to the water inlet pipeline of the cylinder body 13.

[0078] The methanol fuel tank 6 is connected to the oil inlet pipeline of the oil delivery pump body in the fuel injection pump 7, the oil outlet end of the fuel injection pump 7 and the oil outlet end of the fuel delivery pump body therein are both connected to the oil inlet pipeline of the common rail pipe 5, and the input end of the fuel injection pump 7 is connected to the output end pipeline of the oil delivery pump body in the fuel injection pump 7 of the methanol filter 10 with a water jacket; the common rail pipe 5 is simultaneously connected to the pipelines of multiple methanol direct injection nozzles 11 in the cylinder, and the common rail pipe 5 is also connected to the pipeline of the methanol intake duct injection nozzle 4.

[0079] The system further includes a power battery 9 and a temperature sensor 2 . The power battery 9 is electrically connected to the power supply terminal of the electric heating boiler 8 . The temperature sensor 2 is installed in the pipeline between the cylinder head 12 and the electric heating boiler 8 .

[0080] An intake heating grille 3 is provided in the intake duct of the engine to realize intake air heating; the coolant flows from the water outlet of the cylinder head 12 to the electric heating boiler 8, and a temperature sensor 2 is installed near the water outlet of the cylinder head 12. The electric heating boiler 8 is powered by a power battery 9. After being heated in the electric heating boiler 8, the coolant flows to the methanol filter 10 with a water jacket, and finally flows back to the engine from the cylinder block 13 with a water inlet. After the coolant is heated, the methanol in the methanol filter 10 with a water jacket flows to the common rail pipe 5, thereby finally realizing the heating of the coolant and methanol.

[0081] 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. These modifications and improvements will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A control method for improving the cold start performance of a methanol range-extended hybrid system, characterized in that: The method comprises setting an engine start success condition, obtaining a real-time ambient temperature, adopting a first start strategy to start the engine (1) when the real-time ambient temperature is greater than a preset first start temperature, and determining whether the engine (1) has been successfully started based on the engine start success condition; When it is determined that the engine startup fails after adopting the first startup strategy, or the real-time ambient temperature is less than or equal to the first startup temperature and greater than or equal to the preset second startup temperature, the second startup strategy is adopted to start the engine (1), and whether the engine (1) is successfully started is determined based on the engine startup success condition; When it is determined that the engine startup fails after adopting the second startup strategy, or the real-time ambient temperature is lower than the second startup temperature, a third startup strategy is adopted to start the engine (1), and whether the engine (1) is successfully started is determined based on the engine startup success condition.

2. A control method for improving the cold start performance of a methanol range-extended hybrid system according to claim 1, characterized in that: The first startup strategy is: The rotation speed of the engine (1) is dragged to a preset first rotation speed by a motor, methanol direct injection into the cylinder is started, and ignition is performed using a spark plug.

3. The control method for improving the cold start performance of a methanol range-extended hybrid system according to claim 1, characterized in that: The second startup strategy is: After setting a continuous heating time and starting the intake heating grid (3) to heat the intake air for the continuous heating time, the speed of the engine (1) is dragged to a preset first speed by a motor, methanol intake duct injection is started, and ignition is performed using a spark plug.

4. The control method for improving the cold start performance of a methanol range-extended hybrid system according to claim 1, characterized in that: The third startup strategy is: Starting an electric heating boiler (8), electrically heating the coolant flowing out of the water outlet of the cylinder head (12) through the electric heating boiler (8), and then the heated coolant flows through the methanol filter (10) to heat the methanol; obtaining the real-time temperature of the coolant at the water outlet of the cylinder head (12) and the real-time temperature of the methanol in the methanol filter (10), and when the real-time temperature of the coolant is greater than a preset first coolant temperature threshold and the real-time temperature of the methanol is greater than a preset first methanol temperature threshold, shutting down the electric heating boiler (8) to end boiler heating; After the boiler heating is completed, the intake air temperature is obtained, and the intake air is heated for a calibrated intake air heating time according to the intake air temperature; When the intake air heating is completed, the ambient temperature is obtained, the speed preset value is calibrated according to the ambient temperature, the engine speed is dragged to the speed preset value by the motor, and the methanol intake port injection is controlled at the same time, and ignited by a spark plug.

5. The control method for improving the cold start performance of a methanol range-extended hybrid system according to claim 4, characterized in that: When the third starting strategy is adopted, if the engine fails to start, the first coolant temperature threshold is increased to a preset second coolant temperature threshold, and the first methanol temperature threshold is increased to a preset second methanol temperature threshold, and the third starting strategy is activated again according to the second coolant temperature threshold and the second methanol temperature threshold to start the engine.

6. The control method for improving the cold start performance of a methanol range-extended hybrid system according to claim 1, characterized in that: The conditions for successful engine start include: First condition: the engine is in an operational state; Second condition: the engine water temperature and the engine oil temperature of the engine are both greater than the preset starting temperature value; The third condition is that the difference between the actual engine speed and the preset target idle speed is within a preset speed deviation range; Fourth condition: the difference between the actual rail pressure of the engine and the preset target rail pressure is within a preset rail pressure deviation range; Fifth condition: the actual throttle opening of the engine is less than a preset percentage of the maximum throttle opening; Sixth condition: the gear position of the engine is a preset gear position.

7. The control method for improving the cold start performance of a methanol range-extended hybrid system according to claim 1, characterized in that: A switching delay time is set. When it is determined that the engine is started successfully, the switching delay time starts to count; when the switching delay time ends, the methanol intake port injection is switched to methanol direct injection into the cylinder.

8. A system for improving the cold start performance of a methanol range-extended hybrid system, characterized in that: It includes, An air intake heating grille (3) is installed in the air intake duct of the engine (1) and is used to heat the air in the air intake duct; A methanol fuel tank (6) connected to a methanol filter (10) with a water jacket via a pipeline; An electric heating boiler (8) is used to heat the coolant in the engine (1), and to allow the heated coolant to flow through a methanol filter (10) with a water jacket to heat the methanol therein; a methanol intake duct injection nozzle (4), which is installed in the intake duct of the engine (1) and is used to inject methanol into the intake duct of the engine (1); A plurality of methanol in-cylinder direct injection nozzles (11), each mounted on a cylinder head (12) of the engine, for injecting the methanol into a cylinder block (13) of the engine; An ECU, which starts the engine (1) using a control method for improving the cold start performance of a methanol range-extended hybrid system as described in any one of claims 1 to 7.

9. The system for improving the cold start performance of a methanol range-extended hybrid system according to claim 8, characterized in that: The system also includes a common rail pipe (5) and an injection pump (7) integrated with an oil delivery pump body, the water outlet of the cylinder head (12) is connected to the input end pipeline of the electric heating boiler (8), the output end of the electric heating boiler (8) is connected to the water jacket input end pipeline of the methanol filter with a water jacket (10), and the water jacket output end of the methanol filter with a water jacket (10) is connected to the water inlet pipeline of the cylinder body (13); The methanol fuel tank (6) is connected to the oil inlet pipeline of the oil delivery pump body in the fuel injection pump (7); the oil outlet end of the fuel injection pump (7) and the oil outlet end of the fuel delivery pump body therein are both connected to the oil inlet pipeline of the common rail pipe (5); the input end of the fuel injection pump (7) is connected to the oil delivery pump body output pipeline in the fuel injection pump (7) of the methanol filter (10) with a water jacket; the common rail pipe (5) is simultaneously connected to the pipelines of multiple methanol in-cylinder direct injection nozzles (11), and the common rail pipe (5) is also connected to the pipeline of the methanol intake duct injection nozzle (4).

10. The system for improving the cold start performance of a methanol range-extended hybrid system according to claim 8, characterized in that: The system further comprises a power battery (9) and a temperature sensor (2), wherein the power battery (9) is electrically connected to a power supply terminal of the electric heating boiler (8), and the temperature sensor (2) is installed in a pipeline between the cylinder head (12) and the electric heating boiler (8).

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