Methanol engine fuel supply system and control method

Abstract

The invention discloses a methanol engine fuel supply system and a control method. According to the system, an integrated fuel supply structure is adopted, and preheating of methanol fuel is achieved through cooperative work of an electronic methanol pump, a methanol combustion heater, an electronic water pump and a methanol guide rail. The innovation points are as follows: 1) the engine and the heater share a methanol box, a methanol coarse filter, an electronic methanol pump and a methanol fine filter; (2) a methanol combustion heater heats cooling liquid through methanol combustion, and the cooling liquid exchanges heat with methanol fuel through a methanol guide rail; and 3) an intelligent control strategy: when the system automatically judges that the starting mode and the starting condition do not meet the conventional starting mode, automatically entering a cold starting mode and preheating the methanol fuel, displaying the engine starting mode through a signal lamp mode, intelligently judging the engine starting state, and intelligently starting the methanol fuel under the condition that a driver does not start the engine for a long time. The methanol fuel temperature can be maintained through a control program, and the cold start state of the engine is kept.

Description

Technical Field

[0001] The present invention relates to the technical field of methanol engines, and in particular to a fuel supply system and a control method for a methanol engine. Background Art

[0002] Due to the characteristics of methanol fuel, such as a high ignition point temperature (470 °C), a large latent heat of vaporization (1100 kJ / kg), and a low saturated vapor pressure (3.8 kPa @ 20 °C), it is very difficult to cold start a methanol engine in a low-temperature environment. To meet the cold start performance of a methanol engine, there are currently three mainstream solutions for mature countermeasures: The first is to use fuels such as gasoline, diesel, or natural gas as fuels for auxiliary low-temperature cold starts. The disadvantages are high engine and overall vehicle manufacturing costs, a complex fuel system, poor engine reliability, and inconvenient fuel filling for end customers, etc.; The second is to use a boiler to heat the coolant to preheat the engine. The disadvantage is that the boiler still needs to be filled with a second fuel, and the engine coolant has a large capacity, a long preheating time, and it is difficult for the driver to distinguish the preheating effect, resulting in a low cold start success rate; The third is to use an electric motor to reverse-drag the engine for preheating. The disadvantages are: 1. The vehicle must be equipped with a range extender model, and the electric motor has a reverse-dragging function; 2. Preheating requires more than 20 KW·h of electricity, and a certain amount of electricity reserve is needed; 3. The preheating time is long, 20 to 45 minutes; 4. If the cold engine reverse-dragging speed is low, the hot engine effect is poor, and if the speed is high, faults such as cylinder pulling and bearing shell pulling may occur.

[0003] For example, a methanol engine starting system and control method disclosed in Patent CN115962080A includes a methanol engine, and also includes a hybrid system connected to the methanol engine. The hybrid system is arranged in the methanol engine. The hybrid system includes a clutch, a permanent magnet motor, a motor controller, a high-voltage distribution box, a battery, a battery management system, a DC converter, a battery management CAN bus, and related connecting wires; The engine can be reverse-dragged by the ISG to accelerate the heating process, control the exhaust to increase the temperature in the cylinder during the compression process, and the preheating time is long. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a fuel supply system and a control method for a methanol engine to achieve the purpose of quickly preheating to meet the cold start requirements.

[0005] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] A fuel supply system for a methanol engine, comprising:

[0007] A methanol engine and a methanol combustion heater, where the methanol engine and the methanol combustion heater share a methanol tank, a methanol filter, and an electronic methanol pump;

[0008] A methanol guide rail that serves as a heat exchanger. Heat exchange is achieved through the convection of methanol fuel and coolant, resulting in the heating of methanol.

[0009] A water pump is provided between the methanol combustion heater and the engine's methanol guide rail, and the heated coolant is passed into the methanol guide rail for heat exchange to preheat the methanol fuel.

[0010] The methanol filter includes a methanol coarse filter and a methanol fine filter, and the electronic methanol pump is provided between the methanol coarse filter and the methanol fine filter.

[0011] The methanol guide rail is integrated with a methanol nozzle, a methanol temperature sensor, a methanol pressure sensor, and a heater water temperature sensor.

[0012] The methanol fine filter is connected to the inlet of the methanol guide rail, and a pressure control valve is provided between the outlet of the methanol guide rail and the methanol tank.

[0013] It also includes an engine ECU and a signal lamp connected to each other. The methanol temperature sensor, the methanol pressure sensor, and the heater water temperature sensor are all connected to the engine ECU.

[0014] The signal lamp is installed in the cab and is used to display various operating modes.

[0015] An ambient temperature sensor, an engine water temperature sensor, and an engine speed sensor are provided on the engine, and the ambient temperature sensor, the engine water temperature sensor, and the engine speed sensor are all connected to the engine ECU.

[0016] A control method for the methanol engine fuel supply system described above includes the following steps:

[0017] Power-on stage: When the ambient temperature < 15°C and the engine water temperature < 50°C, enter the cold start mode, automatically turn on the methanol combustion heater and the electronic water pump, and start preheating the methanol fuel in the methanol guide rail.

[0018] Start protection stage: After the engine starts successfully, intelligently judge whether the engine coolant temperature ≥ 50°C to avoid the engine stalling again due to the decrease in methanol fuel temperature after successful start.

[0019] The system has a safety protection mechanism. When the methanol temperature sensor detects that the methanol fuel temperature > 60°C, the methanol combustion heater and the electronic water pump are automatically cut off.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. Avoid filling the vehicle with two fuels, gasoline (diesel) and methanol: By adopting the solution of this patent, the vehicle can use methanol as the single fuel, avoiding the use of gasoline (diesel) for engine cold start preheating to improve the cold start performance of the methanol engine, which results in the need to additionally fill gasoline (diesel) for the whole vehicle and increases the fuel usage cost.

[0022] 2. Shorten the engine cold start preheating time: The current mainstream cold start solution for methanol engines in the market is to heat the engine's own coolant through an external boiler of the whole vehicle, while raising the engine water temperature, heating the engine body and lubricating oil temperature. The solution has a complex structure and a long preheating time.

[0023] 3. Directly heat the methanol fuel, which is more conducive to improving the methanol atomization efficiency; The traditional preheating solutions mainly act on the cylinder head and below, and have a poor heating effect on the intake manifold, resulting in poor atomization when the methanol nozzle sprays in the intake manifold and a low cold start success rate.

[0024] 4. Reduce the complexity of the engine fuel system. This solution enables the engine to only require one set of fuel systems, improving the system reliability and reducing the engine cost at the same time.

[0025] 5. Automatically control through the engine ECU; The engine ECU identifies and judges the external conditions. If the engine ECU judges that low-temperature cold start is required, it can automatically operate the methanol fuel heating system and inform the driver of the operating status in the form of a signal lamp; This not only avoids the problem of the driver manually operating the heater in the traditional cold start solution, but also avoids the problem that the driver has insufficient experience and inaccurate judgment of cold start conditions, resulting in cold start failure and repeated heating. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The following briefly describes the content expressed by each drawing in this specification and the marks in the drawings:

[0027] Figure 1 It is a schematic diagram of the fuel supply system of the methanol engine of the present invention.

[0028] Figure 2 It is a schematic diagram of the control method of the fuel supply system of the methanol engine of the present invention.

[0029] In the figure:

[0030] 1. Methanol tank; 2. Coarse methanol filter; 3. Electronic methanol pump; 4. Fine methanol filter; 5. Methanol rail; 6. Methanol nozzle; 7. Methanol pressure sensor; 8. Heater water temperature sensor; 9. Methanol temperature sensor; 10. Pressure control valve; 11. Methanol combustion heater; 12. Electronic water pump; 13. Ambient temperature sensor; 14. Engine water temperature sensor; 15. Engine speed sensor; 16. Engine ECU; 17. Signal lamp. Detailed implementation manners

[0031] The following further describes in detail the specific implementation manners of the present invention by describing the embodiments with reference to the accompanying drawings.

[0032] As Figure 1 and Figure 2 shown, the methanol engine fuel supply system includes a methanol engine, a methanol combustion heater 11, a methanol rail 5, and an electronic water pump 12; the methanol engine and the methanol combustion heater share a methanol tank 1, a methanol filter, and an electronic methanol pump 3; the methanol rail 5 plays a heat exchange role, and heat exchange is achieved through the convection of methanol fuel and coolant to heat the methanol; the water pump is arranged between the methanol combustion heater and the engine methanol rail, and the heated coolant is introduced into the methanol rail for heat exchange to preheat the methanol fuel.

[0033] The methanol filter includes a coarse methanol filter 2 and a fine methanol filter 4, and the electronic methanol pump is arranged between the coarse methanol filter and the fine methanol filter; the fine methanol filter is connected to the inlet of the methanol rail, and a pressure control valve 10 is arranged between the outlet of the methanol rail and the methanol tank.

[0034] The methanol rail is integrated with a methanol nozzle 6, a methanol temperature sensor 9, a methanol pressure sensor 7, and a heater water temperature sensor 8; the fuel state and the heating water state can be monitored in real time, and the integrated layout is compact in structure.

[0035] The system of the present invention further includes an engine ECU 16 and a signal lamp 17 connected to each other. The methanol temperature sensor, the methanol pressure sensor, and the heater water temperature sensor are all connected to the engine ECU; the signal lamp is arranged in the cab and is used to display each operation mode.

[0036] An ambient temperature sensor 13, an engine water temperature sensor 14, and an engine speed sensor 15 are provided on the engine, and the ambient temperature sensor, the engine water temperature sensor, and the engine speed sensor are all connected to the engine ECU.

[0037] The control method of the methanol engine fuel supply system of the present invention includes the following steps:

[0038] Power-on stage: When the ambient temperature < 15°C and the engine coolant temperature < 50°C, enter the cold start mode, automatically turn on the methanol combustion heater and the electronic water pump, and start preheating the methanol fuel in the methanol rail.

[0039] Start protection stage: After the engine starts successfully, intelligently judge whether the engine coolant temperature ≥ 50°C to avoid the engine stalling again due to the decrease in methanol fuel temperature after successful start.

[0040] The system has a safety protection mechanism. When the methanol temperature sensor detects that the methanol fuel temperature > 60°C, automatically cut off the methanol combustion heater and the electronic water pump.

[0041] The fuel heating system uses an external combustion heater to heat the coolant. The coolant exchanges heat with the methanol fuel through the methanol rail components. The methanol combustion heater uses methanol as fuel, converts the chemical energy of the methanol fuel into internal energy through combustion, and quickly heats the coolant through a gas / liquid heat exchanger with the high-temperature gas after methanol combustion. Then the coolant exchanges heat with the methanol fuel through the methanol rail components to achieve the purpose of heating the methanol fuel.

[0042] The system adopts an integrated fuel supply structure, and realizes the preheating of methanol fuel through the coordinated work of the electronic methanol pump, methanol combustion heater, electronic water pump and methanol rail. The innovation points include: 1) The engine and the heater share the methanol tank, methanol coarse filter, electronic methanol pump and methanol fine filter; 2) The methanol combustion heater heats the coolant through methanol combustion, and the coolant exchanges heat with the methanol fuel through the methanol rail; 3) Intelligent control strategy, realizing that the system automatically judges the start mode. When the start conditions do not meet the conventional start mode, it automatically enters the cold start mode and preheats the methanol fuel, shows the engine start mode through the signal lamp, intelligently judges the engine start state, and when the driver does not start the engine for a long time, the methanol fuel temperature can be maintained through the control program to keep the engine in the cold start state.

[0043] The fuel supply system integrates the engine methanol supply system and the methanol heating system. Among them, the methanol heating system is divided into two working modes according to the difference in the engine working state.

[0044] The main features of this system architecture are as follows: 1. The engine uses a single fuel. The combustion heater used in the methanol heating system also uses methanol as fuel, and only one methanol electric pump is used for the whole machine. 2. The heat exchange medium in the methanol heating system is a coolant independent of the engine cooling system and is only used for heating methanol fuel. 3. The methanol supply system is normally open when powered on. The methanol heating system and the engine work together. The engine ECU automatically determines whether methanol fuel needs to be heated based on signals such as the ambient temperature, methanol fuel temperature, coolant temperature, and engine operating status collected, and outputs signals to control the start and stop of the methanol heater.

[0045] The first part of this system architecture, the engine methanol supply system, consists of an electronic methanol pump, a pressure control valve, a methanol rail, a methanol temperature sensor, a methanol pressure sensor, a methanol nozzle, a methanol tank, a methanol coarse filter, a methanol fine filter, an engine ECU, an ambient temperature sensor, signal lights, etc. The methanol engine adopts the intake port fuel injection method. Each cylinder is equipped with an independent methanol injector, which is integrated on the methanol rail. The methanol rail is installed on the engine intake manifold. The methanol inlet pipe of the burner is arranged behind the electronic methanol pump and is connected to the engine methanol pipe through a tee joint. The methanol temperature sensor is arranged on the methanol rail to measure and sense the temperature of the methanol fuel. The methanol pressure sensor is also arranged on the methanol rail to measure and sense the pressure of the methanol fuel. The engine ECU is responsible for controlling the working strategy of the methanol supply system. The ambient temperature sensor is used to sense the ambient temperature. The signal lights are set in the cab of the whole vehicle. There are two bulbs, a red light and a green light, with a total of four display modes. Mode 1 is the cold start mode, the heating system is working, at this time the red light is on and the green light is off; Mode 2 is the cold start mode, the heating system is not working, at this time the red light is on and the green light is on; Mode 3 is the normal start mode, at this time the red light is off and the green light is on; Mode 4 is the engine operating status, at this time the engine is running normally and both the red and green lights are off.

[0046] The second part of this system architecture, the methanol heating system, consists of a methanol combustion heater, a temperature sensor, an electronic water pump, etc. The methanol combustion heater is equipped with a spark plug, a methanol injector, and a heat exchanger, and transfers the heat generated by methanol combustion to the heat exchange medium, the coolant, through the heat exchanger. The electronic methanol pump ensures the pressure and flow rate of the methanol injector in the methanol heater, and the electronic water pump ensures the flow rate of the heat exchange medium, the coolant.

[0047] This methanol heating system and its control method are controlled by the engine ECU. The engine ECU makes the above-mentioned methanol supply system and methanol heating system work together. By collecting the methanol fuel temperature sensor and combining the feedback of signals such as the coolant temperature sensor and ambient temperature in the heating system, it jointly controls the working status of the methanol heating system and the engine.

[0048] This control method has two working modes. Mode 1 is the normal start mode, and Mode 2 is the engine cold start mode. In the normal start mode, the methanol heating system does not operate, and the engine adopts a conventional start strategy, that is, direct start. In the engine cold start mode, after the engine ECU detects that the ambient temperature and the engine coolant are lower than the preset threshold, the engine cold start mode is activated. First, the methanol combustion heater is turned on to heat the coolant. At the same time, the electric water pump is turned on to force the methanol to heat the coolant in a circulating manner, so that the coolant and the methanol fuel in the methanol rail components form a convection, accelerating the heat exchange between the methanol-heated coolant and the methanol fuel.

[0049] One of the features of this patent is that the methanol engine and the methanol heating system use a single fuel, which simplifies the structural design of the engine and the vehicle fuel supply system, reduces the complexity and cost of the fuel system, improves the reliability of the fuel system, and enhances the competitiveness of the engine product.

[0050] Another feature of this patent is that the methanol pump is responsible for the fuel supply of both the methanol combustion heater and the methanol engine. This design feature saves a methanol pump for the methanol heating system and simplifies the engine layout. By using the original large-flow electric methanol pump of the engine to provide the same injection pressure as the engine methanol nozzle for the methanol combustion heater, the methanol atomizes and burns more fully in the combustion heater, with higher thermal efficiency.

[0051] A third feature of this patent is that a coolant independent of the engine cooling system is used to heat the methanol fuel. The coolant has a small capacity, which can achieve a rapid temperature rise of the coolant. Through the drive of the electric water pump, the coolant and the methanol fuel are made to convect, so as to achieve the purpose of quickly heating the methanol fuel.

[0052] A fourth feature of this invention is that this control method is divided into a conventional start mode and a cold start mode. The two start modes are judged by the engine ECU. This control method combines the sensor signals of the engine ECU with the operation control of the fuel heating system, and realizes the full-automatic control of the fuel heating system through the calibration of the control strategy of the engine ECU.

[0053] A fifth feature of this invention is that the working state of the engine fuel supply system and the start mode of the engine are fed back to the driver in the form of light signals through the signal lights arranged in the cab, which is convenient for the driver to understand the real-time working state of the engine methanol supply system and helps the driver judge whether the engine can be ignited and started.

[0054] The specific embodiment is as follows:

[0055] Taking a six-cylinder 15L heavy-duty engine as an example, the specific implementation manner of the patent is further elaborated, aiming to demonstrate the technical features and advantages of this invention patent.

[0056] The engine methanol supply system shares the same methanol tank, methanol coarse filter, electronic methanol pump, methanol fine filter, and methanol rail with the methanol heating system. Methanol nozzles, methanol pressure sensors, water temperature sensors, methanol temperature sensors, and pressure control valves are arranged on the methanol rail.

[0057] The methanol heating system heats the coolant through a methanol combustion heater and forces the coolant to circulate through an electronic water pump, forming a convection with the methanol fuel to achieve the purpose of quickly heating the methanol fuel.

[0058] After the engine is powered on, the electronic methanol pump immediately starts working. The methanol pumping pressure is 0.5 Mpa, and the methanol pumping flow rate is ≥ 360 L / min. The water temperature sensor, methanol temperature sensor, ambient temperature sensor, engine water temperature sensor, and engine speed sensor immediately complete self-checks and transmit signals to the engine ECU. The engine ECU determines the start mode and reflects the engine start status in the form of signal lights.

[0059] Control method for the fuel supply system of a methanol engine:

[0060] Step1: The driver starts the vehicle power supply, and the engine ECU is powered on;

[0061] Step2: The electronic methanol pump is powered on and starts working;

[0062] Step3: The ambient temperature sensor completes the ambient temperature detection and determines whether the ambient temperature is ≥ 15°C. If so, it enters the normal start mode, outputs the signal: the red light is off, the green light is on, and enters Step4; otherwise, it enters Step10;

[0063] Step4: The engine speed sensor completes the engine speed detection and determines whether the engine has started. If so, it outputs the signal: the red light is off, the green light is off, and enters Step5; otherwise, it returns to Step3;

[0064] Step5: The engine water temperature sensor completes the water temperature detection and determines whether the engine coolant water temperature is ≥ 50°C. If so, the program ends; otherwise, it enters Step7;

[0065] Step7: The methanol combustion heater and the electronic water pump start working and enter Step8;

[0066] Step8: The heater water temperature sensor completes the water temperature detection and determines whether the heating water temperature is ≥ 60°C. If so, it enters Step9; otherwise, it enters Step7;

[0067] Step9: The methanol combustion heater and the electronic water pump stop working and enter Step4;

[0068] Step 10: The engine water temperature sensor completes the water temperature detection. Determine whether the engine coolant water temperature is ≥ 50°C. If yes, enter the normal start mode, output the signal: the red light is off and the green light is on, and enter Step 4. Otherwise, enter the cold start mode and enter Step 11;

[0069] Step 11: The methanol combustion heater and the electric water pump start to work, and output the signal: the red light is on and the green light is off; enter Step 12.

[0070] Step 12: The heater water temperature sensor completes the water temperature detection. Determine whether the heating water temperature is ≥ 60°C; then output the signal: the red light is on and the green light is on, and enter Step 9.

[0071] The present invention has the following advantages:

[0072] 1. Avoid filling the vehicle with two fuels, gasoline (diesel) and methanol: With the solution of this patent, the vehicle can use methanol as the single fuel, avoiding the situation that the methanol engine uses gasoline (diesel) for engine cold start preheating to improve cold start performance, which leads to the need to fill the vehicle with additional gasoline (diesel) and increases the fuel usage cost. 2. Shorten the engine cold start preheating time: The current mainstream cold start solution for methanol engines is to heat the engine's own coolant through an external boiler of the vehicle, while raising the engine water temperature, heating the engine body and the lubricating oil temperature. The solution has a complex structure and a long preheating time. 3. Directly heat the methanol fuel, which is more conducive to improving the methanol atomization efficiency; The traditional preheating solution mainly acts on the cylinder head and below, and has a poor heating effect on the intake manifold, resulting in poor atomization when the methanol nozzle sprays in the intake manifold and a low cold start success rate. 4. Reduce the complexity of the engine fuel system. This solution enables the engine to only require one set of fuel system, improves the reliability of the system, and reduces the cost of the engine at the same time. 5. Automatically control through the engine ECU; The engine ECU identifies and judges the external conditions. If the engine ECU determines that low-temperature cold start is required, it can automatically operate the methanol fuel heating system and inform the driver of the operating status in the form of signal lights; This not only avoids the problem of the driver manually operating the heater in the traditional cold start solution, but also avoids the problem that the driver has insufficient experience and misjudges the cold start conditions, resulting in cold start failure and repeated heating.

[0073] The above is only an illustration of the preferred embodiments of the present invention. The above technical features can be arbitrarily combined to form multiple embodiment solutions of the present invention.

[0074] The present invention has been described exemplarily in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above-mentioned manner. As long as various non-substantive improvements are made by adopting the concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A methanol engine fuel supply system, characterized in that: include: A methanol engine and a methanol combustion heater, wherein the methanol engine and the methanol combustion heater share a methanol tank, a methanol filter and an electronic methanol pump; Methanol rails, which play a role in heat exchange, and achieve methanol heating through convection between methanol fuel and coolant; A water pump is arranged between the methanol combustion heater and the engine methanol rail, and passes the heated coolant into the methanol rail for heat exchange to preheat the methanol fuel.

2. The methanol engine fuel supply system as claimed in claim 1, characterized in that: The methanol filter comprises a methanol coarse filter and a methanol fine filter, and the electronic methanol pump is arranged between the methanol coarse filter and the methanol fine filter.

3. The methanol engine fuel supply system as claimed in claim 1, characterized in that: The methanol guide rail is integrated with a methanol nozzle, a methanol temperature sensor, a methanol pressure sensor and a heater water temperature sensor.

4. The methanol engine fuel supply system as claimed in claim 2, characterized in that: The methanol fine filter is connected to the inlet of the methanol guide rail, and a pressure control valve is arranged between the outlet of the methanol guide rail and the methanol tank.

5. The methanol engine fuel supply system as claimed in claim 3, characterized in that: It also includes a connected engine ECU and a signal light, and the methanol temperature sensor, the methanol pressure sensor and the heater water temperature sensor are all connected to the engine ECU.

6. The methanol engine fuel supply system as claimed in claim 5, characterized in that: The signal lights are arranged in the cab and are used to display various operating modes.

7. The methanol engine fuel supply system as claimed in claim 5, characterized in that: The engine is provided with an ambient temperature sensor, an engine water temperature sensor and an engine speed sensor, and the ambient temperature sensor, the engine water temperature sensor and the engine speed sensor are all connected to the engine ECU.

8. A method for controlling a methanol engine fuel supply system as claimed in claim 7, characterized in that: The control method comprises the following steps: Power-on stage: When the ambient temperature is less than 15°C and the engine water temperature is less than 50°C, the engine enters the cold start mode, automatically starts the methanol combustion heater and the electronic water pump, and starts preheating the methanol fuel in the methanol rail; Start protection stage: After the engine is successfully started, it is intelligently determined whether the engine coolant temperature is ≥50°C to avoid the engine shutting down again due to the decrease in methanol fuel temperature after successful starting.

9. The control method according to claim 8, characterized in that: The system is equipped with a safety protection mechanism, which automatically cuts off the methanol combustion heater and the electronic water pump when the methanol temperature sensor detects that the methanol fuel temperature is greater than 60°C.

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