Preheating device for a methanol fuel engine and control method thereof

Abstract

The present application belongs to the technical field of engine preheating control, and provides a preheating device for a methanol fuel engine and a control method thereof. The device comprises a combustion chamber, a heat exchanger, an air-air heat exchanger, an exhaust gas distribution valve and a control unit. The inlet of the combustion chamber is provided with a fuel pump, and an ignition device is arranged in the combustion chamber. The outer side of the combustion chamber is provided with the heat exchanger to heat the engine. The outer side of the combustion chamber is provided with the air-air heat exchanger to increase the intake air temperature of the engine by using the heat of the air-air heat exchanger. The outlet of the combustion chamber is provided with the exhaust gas distribution valve to guide the burned exhaust gas into the aftertreatment system of the engine to preheat the catalyst carrier thereof. The present application can preheat the engine intake pipeline, the engine cylinder and the aftertreatment system at the same time, thereby improving the fuel utilization rate and the space utilization rate, and effectively reducing the emission during the cold start stage of the engine.

Description

Technical Field

[0001] This invention belongs to the field of engine preheating control technology, specifically relating to a preheating device and control method for a methanol fuel engine. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Methanol has a high latent heat of vaporization, which means it cannot fully vaporize at low temperatures, resulting in poor fuel atomization. During cold starts, a large amount of methanol enters the cylinder in liquid form, causing a sharp drop in combustion efficiency, a decrease in exhaust temperature, and a surge in formaldehyde production. Unburned methanol is adsorbed onto the cylinder walls and undergoes a low-temperature oxidation reaction. The catalyst in the aftertreatment process cannot be activated due to the low temperature, and 80% of the formaldehyde emissions during the cold start phase are directly released into the atmosphere.

[0004] To rapidly increase aftertreatment temperature, existing technologies generally employ electric heating aftertreatment and in-cylinder post-injection strategies. Electric heating aftertreatment involves using electrical energy to heat the catalyst, but this method requires high-power batteries, which can lead to a drop in the battery's state of charge (SOC) in hybrid vehicles and may even necessitate forced engine starts for charging, ultimately increasing energy consumption in practical applications. In-cylinder post-injection strategies typically use delayed injection to increase exhaust temperature, which can cause methanol to wet the fuel injectors, forming a formaldehyde polymer layer that easily clogs the injectors and results in reduced power. On the other hand, it can also easily allow unburned methanol to enter the engine oil, causing a decrease in oil viscosity, which in turn accelerates crankshaft wear and significantly shortens the overhaul interval. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes a preheating device and control method for a methanol fuel engine. This invention uses a three-in-one methanol fuel heater to preheat the engine intake manifold, engine block, and aftertreatment system simultaneously, which not only improves fuel utilization and space utilization but also effectively reduces emissions during the engine's cold start phase.

[0006] According to some embodiments, the present invention adopts the following technical solution: A preheating device for a methanol fuel engine includes a combustion chamber, a water-cooled heat exchanger, an air-to-air heat exchanger, an exhaust gas distribution valve, and a control unit, wherein: A fuel pump is installed at the inlet of the combustion chamber to pump methanol fuel into the combustion chamber. An ignition device is installed in the combustion chamber to ignite the methanol mixture in the combustion chamber. A water chamber heat exchanger is provided on the outside of the combustion chamber. One end of the water chamber heat exchanger is connected to a circulating water pump, and the other end is connected to the engine block through a transmission pipeline to heat the engine. An air-to-air heat exchanger is provided on the outside of the combustion chamber. One end of the air-to-air heat exchanger is provided with a wind supply mechanism, and the other end is provided with a hot air duct. The hot air duct is used to connect to the engine intake pipe so as to use the heat of the air-to-air heat exchanger to increase the intake air temperature of the engine. An exhaust gas distribution valve is provided at the outlet of the combustion chamber to guide the exhaust gas after combustion into the engine's aftertreatment system for preheating its catalyst carrier. The control unit is used to control the operation of the ignition device, the fuel pump, the circulating water pump, the air supply mechanism, and the exhaust gas distribution valve.

[0007] The above solution can simultaneously preheat the engine intake manifold, engine block, and after-treatment system, which not only improves fuel efficiency and space utilization, but also effectively reduces emissions during engine cold start.

[0008] As an alternative implementation, the water cavity heat exchanger is provided with coolant, and a first temperature detection module is provided on the water cavity heat exchanger. The first temperature detection module is used to detect the temperature of the coolant, and the first temperature detection module is connected to the control unit.

[0009] As a further defined embodiment, the control unit is configured to start the fuel pump, the ignition device, the circulating water pump, the air supply mechanism, and the exhaust gas distribution valve when the temperature of the coolant is lower than a first threshold, and to shut down the circulating water pump when the temperature of the coolant is higher than a second threshold, wherein the second threshold is greater than the first threshold.

[0010] As an alternative implementation, the wind supply mechanism is a centrifugal fan, which is located on one side of the preheating device, and the preheating device has a fresh air inlet on that side.

[0011] As a further defined embodiment, the centrifugal fan is connected to the control unit, and a second temperature detection module is provided on the engine intake pipe. The second temperature detection module is used to detect the intake air temperature of the engine. The second temperature detection module is connected to the control unit, and the control unit is configured to turn off the centrifugal fan when the intake air temperature is higher than a third threshold.

[0012] As an alternative implementation, a hot air duct valve is provided on the hot air duct, and the hot air duct valve is connected to the control unit.

[0013] As an alternative implementation, the combustion chamber is connected to an exhaust gas pipeline, the exhaust gas pipeline is equipped with an exhaust gas distribution valve, and the exhaust gas pipeline is connected to the aftertreatment system.

[0014] As an alternative implementation, the exhaust gas distribution valve is an electric three-way valve, with the first end connected to the exhaust gas pipeline, the second end connected to the after-treatment system, and the third end connected to the silencer.

[0015] As a further defined embodiment, the aftertreatment system is provided with a third temperature detection module for detecting the catalyst temperature. The third temperature detection module is connected to the control unit, which is configured to switch the exhaust gas distribution valve to the muffler for venting when the catalyst temperature is higher than a fourth threshold, in order to prevent the catalyst carrier from overheating.

[0016] The control method based on the above preheating device includes the following steps: When the coolant temperature is below the first threshold, the fuel pump is started to pump methanol fuel into the combustion chamber for atomization, and the ignition device is started, and the combustion chamber enters the lean combustion mode. The fuel chamber heats the water chamber heat exchanger, and the heated coolant is transferred to the engine block to heat the engine. The combustion chamber heats the air-to-air heat exchanger, and the heated hot air is transmitted to the engine intake manifold to increase the engine intake air temperature. The exhaust gas after combustion in the combustion chamber is transmitted to the engine's aftertreatment system to preheat the catalyst carrier of the aftertreatment system.

[0017] As an alternative implementation, the circulating water pump is turned off when the temperature of the coolant is higher than the second threshold. When the intake air temperature exceeds the third threshold, the air supply mechanism is turned off; When the coolant temperature is higher than the second threshold and the intake air temperature is higher than the third threshold, the heated air is turned off. When the catalyst temperature is higher than the fourth threshold, switch the exhaust gas distribution valve to the silencer to vent the gas to prevent the catalyst carrier from overheating. After the circulating water pump and the wind power supply mechanism are shut down, and the exhaust gas distribution valve is switched, the fuel pump is then shut down to recover waste heat. Cut off the heated air when the engine starts.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The preheating device of the present invention is a three-in-one function, capable of simultaneously preheating the engine intake manifold, engine block, and aftertreatment system; it not only improves fuel utilization and space utilization, but also effectively reduces emissions during the engine cold start phase.

[0019] This invention heats the water chamber heat exchanger through the combustion chamber, and the control unit controls the circulating water pump to start working, transferring heat to the cylinder block through the engine coolant pipeline to heat the engine; the combustion chamber heats the air-to-air heat exchanger, and the control unit turns on the centrifugal fan through a relay and opens the hot air duct valve, transferring the heat from the air-to-air heat exchanger to the engine intake pipeline through the hot air duct to increase the intake air temperature and solve the problem of methanol being difficult to vaporize during the start-up process.

[0020] This invention can also guide the exhaust gas from the heater combustion into the engine aftertreatment system via an exhaust gas distribution valve, preheating the aftertreatment catalyst carrier to quickly reach its optimal operating temperature. This improves aftertreatment conversion efficiency and reduces emissions of harmful gases such as formaldehyde, carbon monoxide, and hydrocarbons during engine start-up and warm-up. During this process, an aftertreatment temperature sensor monitors the temperature in real time. When the temperature reaches a threshold, the exhaust gas distribution valve switches to the muffler for venting, preventing the catalyst carrier from overheating.

[0021] This invention adopts an integrated design, and after testing, it saves 40% of space compared to a standalone system. It is suitable for compact engine compartments, and the reuse of exhaust gas heat energy brings the overall efficiency to 87%. The intake air heating is cut off at the moment of engine start-up, and there is no back pressure interference in exhaust gas heating.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0024] Figure 1 This is a schematic diagram of the structure of a preheating device according to one embodiment; Figure 2 This is a schematic diagram of a preheating device according to one embodiment; Figure 3 This is a schematic diagram of a control method flow according to one embodiment; Figure 4 This is a schematic diagram of a three-way synchronous heating method according to one embodiment; Figure 5 This is a schematic diagram of the operation of a water cavity heat exchanger according to one embodiment; Figure 6 This is a schematic diagram of the operation of an air-to-air heat exchanger according to one embodiment; Figure 7 This is a schematic diagram of the operation of an exhaust gas distribution valve according to one embodiment.

[0025] The components are: 1. Fuel pump; 2. Combustion chamber; 3. Circulating water pump; 4. Heater outlet; 5. Heater exhaust port; 6. Hot air outlet; 7. Water chamber heat exchanger; 8. Air-to-air heat exchanger; 9. Fresh air inlet; 10. Centrifugal fan; 11. Ignition device; 12. Exhaust gas distribution valve; 13. Exhaust gas switching valve; 14. Engine hot water outlet; 15. Engine hot water inlet; and 16. Hot air shut-off valve. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0029] Where there is no conflict, the embodiments and features described in this application may be combined with each other.

[0030] Example 1 A preheating device for a methanol fuel engine, such as Figure 1 As shown, it includes a combustion chamber 2, a heat exchanger, an air-to-air heat exchanger 8, an exhaust gas distribution valve 12, and a control unit, wherein: The combustion chamber 2 is equipped with a fuel pump 1 at its inlet, which is used to pump methanol fuel into the combustion chamber 2. An ignition device 11 is provided in the combustion chamber 2 to ignite the methanol mixture in the combustion chamber 2. A heat exchanger is provided on the outside of the combustion chamber 2. One end of the heat exchanger is connected to the circulating water pump 3, and the other end is connected to the engine block through a transmission pipeline to heat the engine. An air-to-air heat exchanger 8 is provided on the outside of the combustion chamber 2. One end of the air-to-air heat exchanger 8 is provided with a wind supply mechanism, and the other end is provided with a hot air duct. The hot air duct is used to connect to the engine intake pipe so as to use the heat of the air-to-air heat exchanger 8 to increase the intake air temperature of the engine. An exhaust gas distribution valve 12 is provided at the outlet of the combustion chamber 2 to guide the exhaust gas after combustion into the engine's aftertreatment system (or simply aftertreatment) to preheat its catalyst carrier. The control unit is used to control the operation of the ignition device 11, fuel pump 1, circulating water pump 3, air supply mechanism and exhaust gas distribution valve 12.

[0031] like Figure 2 As shown, the preheating device (also known as a heater) simultaneously preheats the engine intake manifold, engine block, and aftertreatment system, which not only improves fuel efficiency and space utilization but also effectively reduces emissions during engine cold start.

[0032] In this embodiment, the heat exchanger is a water-cavity heat exchanger 7, which contains coolant. A first temperature detection module is installed on the heat exchanger to detect the temperature of the coolant. The first temperature detection module is connected to a control unit. The control unit is configured to start the fuel pump 1, ignition device 11, circulating water pump 3, air supply mechanism and exhaust gas distribution valve 12 when the temperature of the coolant is lower than a first threshold, and to shut down the circulating water pump 3 when the temperature of the coolant is higher than a second threshold, wherein the second threshold is greater than the first threshold.

[0033] In this embodiment, the circulating water pump 3 is connected to the engine hot water outlet 14, and the engine hot water inlet 15 is connected to the heater outlet 4, forming a water circulation path.

[0034] In this embodiment, the wind power supply mechanism is preferably a centrifugal fan 10, with a preheating device on one side and a fresh air inlet 9 on the same side. The centrifugal fan 10 is connected to a control unit. A second temperature detection module is provided on the engine intake pipe. The second temperature detection module is used to detect the engine intake temperature. The second temperature detection module is connected to the control unit. The control unit is configured to turn off the centrifugal fan 10 when the intake temperature is higher than a third threshold.

[0035] In this embodiment, a hot air duct valve is provided on the hot air duct, and the hot air duct valve is connected to the control unit.

[0036] The hot air outlet 6 can be connected to the engine hot air inlet, and a hot air shut-off valve 16 is provided at the engine hot air inlet.

[0037] In this embodiment, the combustion chamber 2 is provided with a heater exhaust port 5, the heater exhaust port 5 is connected to an exhaust gas pipeline, the exhaust gas pipeline is provided with an exhaust gas distribution valve 12, and the exhaust gas pipeline is connected to the after-treatment system.

[0038] In this embodiment, the exhaust gas distribution valve 12 is preferably an electric three-way valve, with the first end connected to the exhaust gas pipeline, the second end connected to the aftertreatment system, and the third end connected to the muffler. The aftertreatment system is equipped with a third temperature detection module for detecting the catalyst temperature. The third temperature detection module is connected to the control unit. The control unit is configured to switch the exhaust gas distribution valve 12 to the muffler for venting when the catalyst temperature is higher than a fourth threshold, so as to prevent the catalyst carrier from overheating.

[0039] The after-treatment system is also equipped with an exhaust gas switching valve 13.

[0040] Example 2 Based on the control method of the preheating device provided in Embodiment 1, such as Figure 3 As shown, it includes the following stages: (1) Cold start trigger: When the control unit detects that the coolant temperature is below the threshold, it starts fuel pump 1 to pump methanol fuel into combustion chamber 2 for atomization. Then, the igniter discharges to ignite the methanol-air mixture, and combustion chamber 2 enters lean combustion mode. (2) Three-way synchronous heating: like Figure 4 , Figure 5 As shown, the combustion chamber heats the water chamber heat exchanger, and the control unit controls the circulating water pump 3 to start working, transferring heat to the cylinder block through the engine coolant pipeline to heat the engine. like Figure 6 As shown, the combustion chamber 2 heats the air-to-air heat exchanger 8. The control unit turns on the centrifugal fan 10 via a relay and opens the hot air duct valve to transfer the heat from the air-to-air heat exchanger 8 to the engine intake pipe through the hot air duct, thereby increasing the intake air temperature and solving the problem of methanol being difficult to vaporize during the start-up process.

[0041] like Figure 7 As shown, the control unit directs the exhaust gas from the heater combustion into the engine aftertreatment system via the exhaust gas distribution valve 12. This preheats the aftertreatment catalyst carrier, allowing it to quickly reach its optimal operating temperature, thereby improving the aftertreatment conversion efficiency and reducing the emission levels of harmful gases such as formaldehyde, carbon monoxide, and hydrocarbons during engine start-up and warm-up. During this process, the aftertreatment temperature sensor monitors the temperature in real time. When the temperature reaches a threshold, the exhaust gas distribution valve 12 switches to the muffler for venting, preventing the catalyst carrier from overheating.

[0042] (3) Engine starting stage When the control unit detects that both the coolant temperature and the intake air temperature are greater than the threshold, it shuts off the centrifugal fan 10 and the hot air duct valve (to prevent hot air from affecting the air-fuel ratio during startup, causing the mixture concentration to be too low and startup failure). If the aftertreatment temperature does not reach the set threshold, the exhaust gas heating channel is maintained to continuously preheat the aftertreatment system.

[0043] (4) System Exit After the engine starts successfully, if the temperature of the engine aftertreatment carrier has reached the set threshold, the methanol heater fuel supply valve will be closed and the vent valve will be activated to discharge residual fuel.

[0044] The electric three-way valve switches to the second path, the muffler vents, and the fan and water pump run continuously for a period of time to reduce the temperature of combustion chamber 2, water chamber heat exchanger, and air-to-air heat exchanger 8 to avoid affecting their service life. Once the above temperatures have decreased, the system stops working. The electric three-way valve, based on the ignition signal, immediately closes the heating bypass valve to prevent excessive air from entering the air passage and affecting the air-fuel ratio.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art without creative effort within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A preheating device for a methanol fuel engine, characterized in that, It includes a combustion chamber (2), a water-cooled heat exchanger (7), an air-to-air heat exchanger (8), an exhaust gas distribution valve (12), and a control unit, wherein: A fuel pump (1) is provided at the inlet of the combustion chamber (2), the fuel pump (1) is used to pump methanol fuel into the combustion chamber (2), and an ignition device (11) is provided in the combustion chamber (2) to ignite the methanol mixture in the combustion chamber (2); A water chamber heat exchanger (7) is provided on the outside of the combustion chamber (2). One end of the water chamber heat exchanger (7) is connected to a circulating water pump (3), and the other end is connected to the engine block through a transmission pipeline to heat the engine. An air-to-air heat exchanger (8) is provided on the outside of the combustion chamber (2). One end of the air-to-air heat exchanger (8) is provided with a wind supply mechanism, and the other end is provided with a hot air duct. The hot air duct is used to connect the engine intake pipe so as to use the heat of the air-to-air heat exchanger (8) to increase the intake temperature of the engine. The exhaust gas distribution valve (12) is provided at the outlet of the combustion chamber (2) to introduce the exhaust gas after combustion into the engine's aftertreatment system for preheating its catalyst carrier. The control unit is used to control the operation of the ignition device (11), the fuel pump (1), the circulating water pump (3), the wind power supply mechanism and the exhaust gas distribution valve (12).

2. The preheating device for a methanol fuel engine as described in claim 1, characterized in that, The water cavity heat exchanger (7) is provided with coolant, and a first temperature detection module is provided on the water cavity heat exchanger (7). The first temperature detection module is used to detect the temperature of the coolant, and the first temperature detection module is connected to the control unit.

3. The preheating device for a methanol fuel engine as described in claim 2, characterized in that, The control unit is configured to start the fuel pump (1), the ignition device (11), the circulating water pump (3), the air supply mechanism and the exhaust gas distribution valve (12) when the temperature of the coolant is lower than a first threshold, and to shut down the circulating water pump (3) when the temperature of the coolant is higher than a second threshold, wherein the second threshold is greater than the first threshold.

4. The preheating device for a methanol fuel engine as described in claim 1, characterized in that, The wind power supply mechanism is a centrifugal fan (10), which is located on one side of the preheating device, and a fresh air inlet (9) is provided on this side of the preheating device.

5. The preheating device for a methanol fuel engine as described in claim 4, characterized in that, The centrifugal fan (10) is connected to the control unit. A second temperature detection module is provided on the engine intake pipe. The second temperature detection module is used to detect the intake temperature of the engine. The second temperature detection module is connected to the control unit. The control unit is configured to turn off the centrifugal fan (10) when the intake temperature is higher than a third threshold.

6. The preheating device for a methanol fuel engine as described in claim 1, characterized in that, The hot air duct is equipped with a hot air duct valve, which is connected to the control unit.

7. The preheating device for a methanol fuel engine as described in claim 1, characterized in that, The combustion chamber (2) is connected to an exhaust gas pipeline, and the exhaust gas distribution valve (12) is installed on the exhaust gas pipeline. The exhaust gas pipeline is connected to the after-treatment system.

8. The preheating device for a methanol fuel engine as described in claim 7, characterized in that, The exhaust gas distribution valve (12) is an electric three-way valve, with the first end connected to the exhaust gas pipeline, the second end connected to the after-treatment system, and the third end connected to the silencer; The aftertreatment system is equipped with a third temperature detection module for detecting the catalyst temperature. The third temperature detection module is connected to the control unit. The control unit is configured to switch the exhaust gas distribution valve (12) to the muffler to vent when the catalyst temperature is higher than a fourth threshold, so as to prevent the catalyst carrier from overheating.

9. A control method for the preheating device according to any one of claims 1-8, characterized in that, Includes the following steps: When the coolant temperature is below the first threshold, the fuel pump (1) is started to pump methanol fuel into the combustion chamber (2) for atomization, and the ignition device (11) is started, and the combustion chamber (2) enters the lean combustion mode; The fuel chamber (2) heats the water chamber heat exchanger (7), and the heated coolant is transferred to the engine block to heat the engine. The combustion chamber (2) heats the air-to-air heat exchanger (8), and the heated hot air is transmitted to the engine intake pipe to increase the engine intake temperature. The exhaust gas after combustion in the combustion chamber (2) is transmitted to the engine's aftertreatment system to preheat the catalyst carrier of the aftertreatment system.

10. The control method as described in claim 9, characterized in that, When the temperature of the coolant is higher than the second threshold, the circulating water pump is turned off (3); When the intake air temperature exceeds the third threshold, the air supply mechanism is turned off; When the coolant temperature is higher than the second threshold and the intake air temperature is higher than the third threshold, the heated air is turned off. When the catalyst temperature is higher than the fourth threshold, switch the exhaust gas distribution valve (12) to the silencer to vent the gas to prevent the catalyst carrier from overheating. After the circulating water pump (3) and the wind power supply mechanism are shut down and the exhaust gas distribution valve (12) is switched, the fuel pump (1) is shut down to recover waste heat. Cut off the heated air when the engine starts.

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