Structure and method for cold start of methanol engine

Abstract

The invention discloses a methanol engine cold start structure and method, and relates to the field of methanol engine cold start, the methanol engine cold start structure comprises an engine, the top of the engine is provided with a cold start assembly, the cold start assembly comprises an air inlet and exhaust connecting pipe, and the two ends of the air inlet and exhaust connecting pipe are fixedly connected with an air inlet and exhaust pipe of the engine respectively; the cold start nozzle is fixedly connected with the inner wall of the intake and exhaust connecting pipe; the methanol feeding pipe is communicated with one side of the cold start nozzle; the gas flow control valve is fixedly mounted on the intake and exhaust connecting pipe; the oxygen sensor is mounted on an exhaust pipe of the engine; according to the cold start structure of the methanol engine, an expensive cold start system does not need to be added to start an automobile through the cold start assembly; during starting, long-time waiting is not needed; the risk caused by wiring harness arrangement of the electric heating system is avoided; in an engine with a high-pressure EGR system, a cold start nozzle can be arranged on an EGR pipeline; in a self-priming engine with EGR, the cold start nozzle can be arranged on an EGR pipeline, and an EGR cooling system stops working when the engine is started.

Description

Technical Field

[0001] The invention relates to a methanol engine cold start technology, and in particular to a methanol engine cold start structure and method. Background Art

[0002] Methanol is a clean fuel that can replace gasoline or diesel in internal combustion engines. The main sources of methanol are: (1) coal-to-methanol, which reduces energy dependence on petroleum, and (2) green methanol synthesized from carbon dioxide and hydrogen. Methanol fuel is a must for "dual carbon" and will bring disruptive changes to the automotive and shipping industries. The cold start of methanol engines is a bottleneck in the application of methanol engines.

[0003] Methanol has a large latent heat of evaporation. The latent heat of vaporization of methanol is 1109 kJ / kg, which is 3.7 times that of gasoline (310 kJ / kg). Under one atmosphere, the evaporation temperature of methanol is 65 degrees Celsius. Under low temperature conditions, since the latent heat of vaporization of methanol is much higher than that of gasoline, methanol gasoline will have poor cold start performance. Technical measures need to be taken to solve this problem.

[0004] Known methanol engine cold start methods include: (1) dual fuel system, one set of gasoline fuel supply and injection system, one set of methanol fuel supply and injection system. Gasoline is used at the start, and when the cooling water temperature reaches 65 degrees Celsius, the methanol system is switched to; (2) electric heating of cooling water. The cooling water circulating in the engine is heated by a heating wire, and when the water temperature reaches above 65 degrees Celsius, the methanol system is started; (3) a glow plug is arranged next to the fuel injector. After the glow plug is heated, methanol is sprayed on the glow plug, and the methanol is vaporized, mixed with fresh air, and enters the cylinder for combustion; (4) the heating wire is wound around the fuel rail to heat the fuel. After the heated methanol is sprayed through the nozzle, it mixes with the air and enters the cylinder for combustion; (5) the heat of the engine exhaust is used to crack the methanol to produce hydrogen or dimethyl ether. When the engine is started, the hydrogen or dimethyl ether is sprayed into the cylinder for combustion. After the engine is heated, the methanol injection system is switched to.

[0005] In the existing methanol cold start scheme, (1) dual fuel system, this system requires two fuel systems, one gasoline fuel supply and injection system, and one methanol fuel supply and injection system. This system is costly and requires a large layout space. It is inconvenient to use because two fuels need to be added. (2) Electric heating of cooling water. An electric heating device is required, which increases the cost and wiring harness layout space requirements. There are electromagnetic interference and safety hazards. In addition, the cooling water heating time is long, and the user experience is poor. (3) Electric glow plugs are arranged next to the fuel injector. Increase the wiring harness layout space requirements. There are electromagnetic interference and safety hazards. When the engine is working normally, the gas flow loss increases. (4) Methanol cracking. It is necessary to add a cracking device and a hydrogen (dimethyl ether) storage and injection system. The cost is high and the layout is difficult. Summary of the invention

[0006] The purpose of the present invention is to provide a structure for cold starting of a methanol engine to solve the above-mentioned deficiencies in the prior art.

[0007] In order to achieve the above object, the present invention provides the following technical solution: a structure for cold starting a methanol engine, comprising an engine, a cold starting assembly is installed on the top of the engine, and the cold starting assembly comprises:

[0008] An intake and exhaust connecting pipe, the two ends of which are respectively fixedly connected to the intake pipe and the exhaust pipe of the engine;

[0009] A cold start nozzle, which is fixedly connected to the inner wall of the intake and exhaust connecting pipe;

[0010] a methanol feed pipe connected to one side of the cold start nozzle;

[0011] A gas flow control valve, which is fixedly installed on the inlet and exhaust connecting pipes;

[0012] Oxygen sensor, which is installed on the exhaust pipe of the engine.

[0013] Furthermore, the engine comprises:

[0014] An air intake pipe connected to one end of the air intake and exhaust connecting pipe;

[0015] An intake manifold, one end of which is connected to the intake pipe;

[0016] a housing, one side of which is connected to the other end of the intake manifold;

[0017] The throttle valve is sleeved on the outside of the intake pipe.

[0018] Furthermore, the engine further comprises:

[0019] a piston slidably connected to the inner wall of the housing;

[0020] An exhaust pipe connected to the other end of the intake and exhaust connecting pipe;

[0021] An exhaust manifold has one end connected to the other side of the housing and the other end connected to the exhaust pipe.

[0022] A method for cold starting a methanol engine, which is applicable to the structure for cold starting a methanol engine according to any one of claims 1 to 3, and is characterized by comprising the following steps:

[0023] S1. The motor drives the engine to rotate, and the engine is used as a compressor to provide high-temperature gas; the obtained high-temperature exhaust gas flows through the intake and exhaust connecting pipes;

[0024] S2, using the exhaust VVT variable valve timing to open the exhaust valve in advance, reduce the gas temperature drop caused by expansion, increase the exhaust temperature, and maintain a certain amount of residual gas in the cylinder (generally not more than 25%);

[0025] S3. Spray methanol into the intake and exhaust connecting pipes through the cold start nozzle.

[0026] Furthermore, the method further comprises the following steps:

[0027] S11. When the engine is cold started, the cold start nozzle sprays methanol into the intake and exhaust connecting pipes, so that the methanol is mixed with the gas, and part of the methanol is attached to the wall of the intake and exhaust connecting pipes;

[0028] S12, methanol is heated and vaporized by the high-temperature gas flowing through the intake and exhaust connecting pipes;

[0029] S13, the methanol mixed gas flows into the intake pipe through the intake and exhaust connecting pipe, enters the cylinder and burns;

[0030] S14. After the engine is warm and the cooling water temperature reaches above 65°, close the cold start nozzle to allow the conventional nozzle to operate normally.

[0031] Furthermore, the method further comprises the following steps:

[0032] S21. When the engine is started, the cold start nozzle and the throttle are closed, the motor drives the engine to rotate, and a vacuum is generated in the intake manifold and the engine cylinder;

[0033] S22, the latent heat of methanol is reduced under vacuum, and methanol evaporates after being sprayed into the airway wall;

[0034] S23, after the oxygen sensor detects methanol gas, the throttle valve opens and the engine starts;

[0035] S24. During startup, the methanol injection strategy is adjusted to maintain a certain amount of methanol surplus in the mixed gas. The unburned methanol is gasified at high temperature by the burned gas, of which generally no more than 25% remains in the residual exhaust gas in the cylinder to participate in the next cycle combustion; when there is a stable gas flow in the intake and exhaust connecting pipes, the methanol injection strategy is adjusted to eliminate the methanol surplus;

[0036] S25. The high-temperature exhaust gas after combustion returns to the intake passage through the intake and exhaust connecting pipes, heats the methanol injected into the air passage or cylinder, vaporizes it, and maintains the continuous operation of the engine;

[0037] S26. This method does not require the installation of a cold start nozzle.

[0038] Furthermore, the method further comprises the following steps:

[0039] S31, reduce the back pressure valve opening, increase the exhaust gas recirculation flow rate into the cylinder;

[0040] S32, the high-temperature exhaust heats the inner wall of the engine intake duct through the intake and exhaust connecting pipe; when the inner wall temperature is higher than 65 degrees Celsius, methanol is sprayed into the intake duct nozzle, the methanol is vaporized, and the engine is started;

[0041] S33, this method takes a long time to start, but does not require the installation of a cold start nozzle;

[0042] S34. The high-pressure EGR system of a supercharged engine or the EGR system of a naturally aspirated engine may be used to replace the intake and exhaust connecting pipes.

[0043] Compared with the prior art, the cold start structure of a methanol engine provided by the present invention enables the car to be started without the need for an additional expensive cold start system through a cold start component; no long waiting time is required during starting; the risks caused by the wiring harness arrangement of the electric heating system are avoided; in an engine with a high-pressure EGR system, the cold start nozzle can be arranged on the EGR pipe; in an engine with an EGR self-priming system, the cold start nozzle can be arranged on the EGR pipe, and the EGR cooling system stops working during starting. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0045] Figure 1 A three-dimensional diagram of the overall structure provided by an embodiment of the present invention;

[0046] Figure 2 A longitudinal sectional perspective view of the overall structure provided by an embodiment of the present invention;

[0047] Figure 3 A general longitudinal sectional perspective view of a cold start assembly structure provided by an embodiment of the present invention;

[0048] Figure 4 A plan view of the overall structure provided by an embodiment of the present invention;

[0049] Figure 5 Other connection methods of the intake and exhaust pipes at the exhaust end provided in the embodiments of the present invention;

[0050] Figure 6 Other connection methods of the intake and exhaust pipes at the intake end provided in the embodiments of the present invention.

[0051] Description of reference numerals:

[0052] 1. Engine; 11. Exhaust manifold; 12. Exhaust pipe; 13. Casing; 14. Piston; 15. Intake manifold; 16. Intake pipe; 17. Throttle valve; 2. Cold start assembly; 21. Intake and exhaust connecting pipes; 22. Cold start nozzle; 23. Methanol feed pipe; 24. Gas flow control valve; 25. Oxygen sensor. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0054] Embodiment 1:

[0055] See also Figure 1-Figure 4 A methanol engine cold start structure includes an engine 1, a cold start component 2 is installed on the top of the engine 1, and the cold start component 2 includes:

[0056] An intake and exhaust connecting pipe 21, both ends of which are fixedly connected to the intake pipe 16 and the exhaust pipe 12 of the engine 1 respectively;

[0057] A cold start nozzle 22, which is fixedly connected to the inner wall of the intake and exhaust connecting pipe 21;

[0058] a methanol feed pipe 23, which is connected to one side of the cold start nozzle 22;

[0059] A gas flow control valve 24, which is fixedly mounted on the inlet and outlet connecting pipe 21;

[0060] The oxygen sensor 25 is mounted on the exhaust pipe 12 of the engine 1 .

[0061] In a specific implementation, a cold start nozzle 22, a gas flow control valve 24 and an oxygen sensor 25 are all electrically connected to an external power source and controlled by an engine control unit (ECU). The cold start nozzle 22 is used to spray methanol into the intake and exhaust connecting pipe 21, the gas flow control valve 24 is used to adjust the gas flow through the intake and exhaust connecting pipe 21, and the oxygen sensor 25 is used to detect methanol gas.

[0062] The engine 1 includes:

[0063] An air intake pipe 16, which is connected to one end of an air intake and exhaust connecting pipe 21;

[0064] An intake manifold 15, one end of which is connected to an intake pipe 16;

[0065] The housing 13 has one side connected to the other end of the intake manifold 15;

[0066] a throttle valve 17 arranged outside the intake pipe 16;

[0067] A piston 14 slidably connected to the inner wall of the housing 13;

[0068] An exhaust pipe 12, which is connected to the other end of the intake and exhaust connecting pipe 21;

[0069] One end of the exhaust manifold 11 is connected to the other side of the housing 13 , and the other end thereof is connected to the exhaust pipe 12 .

[0070] In a specific embodiment, the intake manifold 15 includes an independent exhaust manifold and an exhaust manifold integrated in the cylinder head of the engine 1 .

[0071] Embodiment 2:

[0072] See also Figure 1-4 This embodiment provides an implementation method based on the first embodiment, a method for cold starting a methanol engine, which is applicable to a structure for cold starting a methanol engine according to any one of claims 1 to 3, comprising the following steps:

[0073] S1, the motor drives the engine 1 to rotate, and the engine 1 is used as a compressor to provide high-temperature gas; the obtained high-temperature exhaust gas flows through the intake and exhaust connecting pipe 21;

[0074] S2, using the exhaust VVT variable valve timing to open the exhaust valve in advance, reduce the gas temperature drop caused by expansion, increase the exhaust temperature, and maintain a certain amount of residual gas in the cylinder (generally not more than 25%);

[0075] S3, spraying methanol into the intake and exhaust connecting pipe 21 through the cold start nozzle 22;

[0076] S11, when the engine 1 is cold started, the cold start nozzle 22 sprays methanol into the intake and exhaust connecting pipe 21, so that the methanol is mixed with the gas, and part of the methanol is attached to the wall of the intake and exhaust connecting pipe 21;

[0077] S12, methanol is heated and vaporized by the high-temperature gas flowing through the intake and exhaust connecting pipe 21;

[0078] S13, the methanol mixed gas flows into the intake pipe 16 through the intake and exhaust connecting pipe 21, enters the cylinder and burns;

[0079] S14: After the engine 1 is warmed up and the cooling water temperature reaches above 65°, the cold start nozzle 22 is closed to allow the conventional nozzle to operate normally.

[0080] Embodiment three:

[0081] See also Figure 1-4 This embodiment provides an implementation method based on the first embodiment, a method for cold starting a methanol engine, which is applicable to a structure for cold starting a methanol engine according to any one of claims 1 to 3, comprising the following steps:

[0082] S21, when the engine 1 is started, the cold start nozzle 22 and the throttle valve 17 are closed, the motor drives the engine 1 to rotate, and a vacuum is generated in the intake manifold 15 and the cylinder of the engine 1;

[0083] S22, the latent heat of methanol is reduced under vacuum, and methanol evaporates after being sprayed into the airway wall;

[0084] S23, after the oxygen sensor 25 detects methanol gas, the throttle valve 17 is opened and the engine 1 is started;

[0085] S24, when starting, adjust the methanol injection strategy to maintain a certain amount of methanol in the mixed gas, and the unburned methanol is gasified at high temperature by the burned gas, of which generally no more than 25% remains in the exhaust gas in the cylinder to participate in the next cycle combustion; when there is a stable gas flow in the intake and exhaust connecting pipe 21, adjust the methanol injection strategy to eliminate the methanol richness;

[0086] S25, the high-temperature exhaust gas after combustion returns to the intake passage through the intake and exhaust connecting pipe 21, heats the methanol injected into the air passage or the cylinder, vaporizes it, and maintains the continuous operation of the engine 1;

[0087] S26. This method does not require the installation of the cold start nozzle (22).

[0088] Embodiment 4:

[0089] See also Figure 1-4 This embodiment provides an implementation method based on the first embodiment, a method for cold starting a methanol engine, which is applicable to a structure for cold starting a methanol engine according to any one of claims 1 to 3, comprising the following steps:

[0090] S31, reduce the back pressure valve opening, increase the exhaust gas recirculation flow rate into the cylinder;

[0091] S32, the high-temperature exhaust gas heats the inner wall of the intake duct of the engine 1 through the intake and exhaust connecting pipe 21; when the inner wall temperature is higher than 65 degrees Celsius, methanol is sprayed into the intake duct nozzle, the methanol is vaporized, and the engine 1 is started;

[0092] S33, this method takes a long time to start, but there is no need to install the cold start nozzle 22;

[0093] S34. The intake and exhaust connecting pipe 21 may be replaced by a high-pressure EGR system of a supercharged engine or an EGR system of a naturally aspirated engine.

[0094] Embodiment five:

[0095] See also Figure 5-6This embodiment provides an implementation method based on the first embodiment, wherein one end of the intake and exhaust connecting pipe 21 is connected to the intake manifold 15 , and the other end of the intake and exhaust connecting pipe 21 is connected to the exhaust manifold 11 .

[0096] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A methanol engine cold start structure, comprising an engine (1), characterized in that: A cold start assembly (2) is installed on the top of the engine (1), and the cold start assembly (2) comprises: An intake and exhaust connecting pipe (21), the two ends of which are respectively fixedly connected to the intake pipe (16) and the exhaust pipe (12) of the engine (1); A cold start nozzle (22) fixedly connected to the inner wall of the intake and exhaust connecting pipe (21); a methanol feed pipe (23) connected to one side of the cold start nozzle (22); A gas flow control valve (24) fixedly mounted on the inlet and outlet connecting pipe (21); An oxygen sensor (25) is mounted on the exhaust pipe (12) of the engine (1).

2. The cold start structure of a methanol engine according to claim 1, characterized in that: The engine (1) comprises: An air intake pipe (16) connected to one end of an air intake and exhaust connecting pipe (21); An intake manifold (15), one end of which is connected to an intake pipe (16); A housing (13) having one side connected to the other end of the intake manifold (15); The throttle valve (17) is arranged outside the intake pipe (16).

3. The cold start structure of a methanol engine according to claim 2, characterized in that: The engine (1) further comprises: A piston (14) slidably connected to the inner wall of the housing (13); An exhaust pipe (12) connected to the other end of the intake and exhaust connecting pipe (21); An exhaust manifold (11) has one end connected to the other side of the housing (13), and the other end connected to the exhaust pipe (12).

4. A method for cold starting a methanol engine, which is applicable to the cold starting structure of a methanol engine according to any one of claims 1 to 3, characterized in that: The steps include: S1, the motor drives the engine (1) to rotate, and the engine (1) is used as a compressor to provide high-temperature gas; the obtained high-temperature exhaust gas flows through the intake and exhaust connecting pipe (21); S2. Using the exhaust VVT variable valve to open the exhaust valve in advance, reduce the gas temperature drop caused by expansion, increase the exhaust temperature, and maintain a certain amount of residual gas in the cylinder (generally not more than 25%); S3, spraying methanol into the intake and exhaust connecting pipe (21) through the cold start nozzle (22).

5. The method for cold starting a methanol engine according to claim 4, characterized in that: The following steps are also included: S11, when the engine (1) is cold started, the cold start nozzle (22) sprays methanol into the intake and exhaust connecting pipe (21), so that the methanol is mixed with the gas, and part of the methanol is attached to the wall of the intake and exhaust connecting pipe (21); S12, methanol is heated and vaporized by the high-temperature gas flowing through the intake and exhaust connecting pipe (21); S13, the methanol mixed gas flows into the intake pipe (16) through the intake and exhaust connecting pipe (21), enters the cylinder and burns; S14: After the engine (1) is warmed up and the cooling water temperature reaches 65°, the cold start nozzle (22) is closed, so that the conventional nozzle operates normally.

6. The method for cold starting a methanol engine according to claim 4, characterized in that: The following steps are also included: S21, when the engine (1) is started, the cold start nozzle (22) and the throttle valve (17) are closed, and the motor drives the engine (1) to rotate, thereby generating a vacuum in the intake manifold (15) and the cylinder of the engine (1); S22, the latent heat of methanol is reduced under vacuum, and methanol evaporates after being sprayed into the airway wall; S23, after the oxygen sensor (25) detects methanol gas, the throttle valve (17) is opened and the engine (1) is started; S24, when starting, adjusting the methanol injection strategy to maintain a certain amount of methanol surplus in the mixed gas, unburned methanol, and high-temperature gasification generated by the burned gas, of which generally no more than 25% remains in the residual exhaust gas in the cylinder to participate in the next cycle combustion; when there is a stable gas flow in the intake and exhaust connecting pipe (21), adjusting the methanol injection strategy to eliminate the methanol surplus; S25, the high-temperature exhaust gas after combustion returns to the intake passage through the intake and exhaust connecting pipe (21), heats the methanol injected into the air passage or the cylinder, vaporizes it, and maintains the continuous operation of the engine (1); S26. This method does not require the installation of a cold start nozzle (22) 7. The method for cold starting a methanol engine according to claim 4, characterized in that: The following steps are also included: S31, reduce the back pressure valve opening, increase the exhaust gas recirculation flow rate into the cylinder; S32, the high-temperature exhaust gas heats the inner wall of the intake duct of the engine (1) through the intake and exhaust connecting pipe (21); when the temperature of the inner wall is higher than 65 degrees Celsius, methanol is sprayed into the intake duct nozzle, the methanol is vaporized, and the engine (1) is started; S33, this method takes a long time to start, but does not require the installation of a cold start nozzle (22); S34. The high-pressure EGR system of a supercharged engine or the EGR system of a naturally aspirated engine may be used to replace the intake and exhaust connecting pipe (21).

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