CN109973266B

CN109973266B - Multistage-injection methanol engine cold start device and method

Info

Publication number: CN109973266B
Application number: CN201811578131.2A
Authority: CN
Inventors: 蒋炎坤; 王睿鑫
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2018-12-20
Filing date: 2018-12-20
Publication date: 2020-07-10
Anticipated expiration: 2038-12-20
Also published as: CN109973266A

Abstract

The invention belongs to the field of cold start of methanol engines, and discloses a multistage-injection methanol engine cold start device and method. The device includes methyl alcohol evaporation and schizolysis module and methyl alcohol multi-stage injection and ignition module, and methyl alcohol evaporation and schizolysis module include consecutive first intake duct, combustion chamber, evaporation and schizolysis room and blast pipe, and methyl alcohol multi-stage injection and ignition module include methyl alcohol case, methyl alcohol high pressure oil rail, methyl alcohol pump, one-level methyl alcohol sprayer, second grade methyl alcohol sprayer, spark plug and controller. The invention also discloses a cold start method of the multistage-injection methanol engine. The methanol cracking gas can be prepared under the condition of lower environmental temperature by multi-stage injection methanol single ignition under the cold start condition, and the methanol cracking gas and the un-cracked methanol gas are introduced into the engine together to realize the quick cold start of the pure methanol engine.

Description

Multistage-injection methanol engine cold start device and method

Technical Field

The invention belongs to the technical field of cold start of methanol engines, and particularly relates to a multistage-injection methanol engine cold start device and method.

Background

Because methanol has large latent heat of vaporization, the methanol is difficult to evaporate to form combustible mixed gas with air in a low-temperature environment, thereby causing the phenomenon of difficult cold start. The existing technical means for solving the problem of cold start of the methanol engine mainly comprise: and (5) installing a preheating device. The preheating device comprises an air inlet pipe preheating device, a first air inlet channel preheating device, an oil rail preheating device and an injector preheating device. The air heated by the air inlet pipe is relatively far away from the air cylinder, can not directly act on the initial circulation of cold starting, and has a large amount of heat loss along the way, so that the heating effect is poor. The first inlet preheating responds relatively quickly by installing a heating device, typically a glow plug, a mesh heating wire, etc., in the first inlet, but the heater heating temperature and time need to be controlled to avoid the heater igniting the mixture in the first inlet. The oil rail preheating is a method for solving the cold start problem by heating fuel, but the oil rail preheating heating speed is low, and the heat loss is large.

In order to overcome the problem of difficult cold start of methanol, high volatile substances such as isopentane and petroleum ether are generally added into the methanol fuel. But also requires the design of specialized high volatility fuel storage tanks that are not readily available on board the vehicle. The other is blended with gasoline, which improves the cold start performance of the engine, but two fuel tanks are still required and cannot completely replace fossil fuel. The other method is that the methanol cracking gas is utilized, liquid methanol is heated by a direct current heating wire of a catalytic cracking mechanism and catalyzed by a catalyst, the liquid methanol is changed into gaseous methanol, the gaseous methanol enters a piston cavity, the pressure of the methanol is controlled by an electromagnetic valve and a pressure sensor of a compression mechanism, and the heated and cracked gaseous methanol is sprayed into an engine by a nozzle of a spraying mechanism to finish cold starting. Similarly, the prior art also discloses a methanol cold start-up device, which vaporizes and cracks methanol supplied from a methanol supply device under low temperature conditions, wherein the methanol is vaporized to form methanol vapor, and the methanol vapor is further cracked to form carbon monoxide and hydrogen. The mixer is used for mixing the methanol steam which is not cracked in the cracking gas-making device and the carbon monoxide and the hydrogen which are generated after cracking, outputting the mixture to the engine, and realizing the low-temperature cold start work of the engine by burning the mixed gas which is input into the engine. The above prior art provides heat for methanol cracking by means of electric heating, the electric heating provides heat for a long time, the energy density is not high, and special heating parts need to be provided.

Disclosure of Invention

Aiming at the defects or improvement requirements of the prior art, the invention provides a methanol engine cold start device with multi-stage injection and single ignition, wherein multi-stage injection of methanol is adopted for single ignition under the condition of cold start, so that relatively clean methanol cracking gas with higher heat value, wide ignition limit and lower ignition energy is prepared, and the methanol cracking gas and the un-cracked methanol gas are introduced into an engine together to realize the rapid cold start of a pure methanol engine.

To achieve the above objects, according to one aspect of the present invention, there is provided a multi-injection methanol engine cold start apparatus including a methanol evaporation and decomposition module and a methanol multi-injection and ignition module, wherein,

the methanol evaporation and cracking module comprises a first air inlet channel, a combustion chamber, an evaporation and cracking chamber and an exhaust pipe which are sequentially connected, the evaporation and cracking chamber further comprises a catalyst arranged in the evaporation and cracking chamber, and the tail end of the exhaust pipe is connected with an air inlet of an engine;

the methanol multi-stage injection and ignition module comprises a methanol tank, a methanol high-pressure oil rail, a methanol pump, a first-stage methanol injector, a second-stage methanol injector, a spark plug and a controller, the methanol tank is connected with the methanol high-pressure oil rail through the methanol pump, the methanol high-pressure oil rail is connected with the first-stage methanol injector and the second-stage methanol injector respectively, the spark plug is arranged in the first air inlet channel, the first-stage methanol injector is arranged on one side far away from the combustion chamber, the spark plug is arranged on one side near the combustion chamber, the second-stage methanol injector is arranged at the air inlet end of the evaporation and cracking chamber, the controller is connected with the first-stage methanol injector, the second-stage methanol injector and the spark plug respectively and is used for controlling the injection quantity of the first-stage methanol injector and the second-stage methanol injector and the ignition time of the spark plug, to achieve multiple injections and a single ignition.

Furthermore, a first electromagnetic valve is arranged on the primary methanol ejector and connected with the controller, and a second electromagnetic valve is arranged on the secondary methanol ejector and connected with the controller.

Further, the spark plug is arranged in an alcohol-rich mixed gas area formed by liquid methanol and air injected by the primary methanol injector.

Further, the catalyst is a metal catalyst.

Further, the methanol tank is connected with the methanol pump through a corrosion-resistant pipeline, and the methanol pump is connected with the methanol high-pressure oil rail through the corrosion-resistant pipeline.

Further, the methanol multi-stage injection and ignition module further comprises a vehicle-mounted battery, and the vehicle-mounted battery is connected with the controller.

Furthermore, the evaporation and cracking chamber also comprises a screen arranged in the evaporation and cracking chamber, and the screen is used for fixing the catalyst

According to another aspect of the present invention, there is provided a cold start method of a methanol engine with multi-injection, comprising the steps of:

s1, starting the engine, enabling the first air inlet channel to suck air, and simultaneously enabling the controller to control the first-stage methanol injector to inject liquid methanol into the first air inlet channel, so that the air is mixed with the methanol to form an alcohol-rich mixed gas area in the first air inlet channel;

s2 the controller controls the spark plug to ignite in the rich alcohol gas mixture area, the injected methanol and air are burnt in the combustion chamber, at the same time, a large amount of heat is released to form hot air flow;

the S3 controller controls the secondary methanol injector to inject liquid methanol into the evaporation and cracking chamber, the liquid methanol is mixed with hot air flow and evaporated into gaseous methanol under the heating action of the hot air flow, the gaseous methanol generates methanol cracking gas under the action of the catalyst, so that high-temperature mixed gas containing the methanol cracking gas is formed, and the high-temperature mixed gas enters the engine through the exhaust pipe to promote the methanol engine to realize low-temperature cold start.

Further, in the step S1, the mass ratio of the air to the methanol gas is 3.2:1-6.4: 1; in the step S3, the mass ratio of the air intake of the engine to the liquid methanol injected by the secondary methanol injector is 3.2:1-6.4: 1.

Further, the methanol gas not cracked in S3 enters the engine through the exhaust pipe to further promote the methanol engine to realize a cold start at a low temperature.

Generally, compared with the prior art, the above technical solution conceived by the present invention mainly has the following technical advantages:

1. the device has the advantages that the methanol pyrolysis gas which is higher in heat value, wide in ignition limit, lower in ignition energy and relatively clean can be prepared under the condition of lower environmental temperature by multi-stage injection of methanol for single ignition under the cold start condition, the methanol pyrolysis gas and the un-cracked methanol gas are introduced into the engine together to realize the rapid cold start of the pure methanol engine, the device is high in stability and low in power consumption, other fuels are not required to be provided, the device is simple to refit on the original engine, the device is only required to be additionally arranged on the air inlet of the original engine, and the industrial production is easy.

2. The invention is provided with the multistage methanol injector, can realize the evaporation and the cracking of the methanol liquid by injecting methanol for many times and injecting for many times through single ignition without adding other auxiliary preheating devices, and further can prepare the relatively clean methanol pyrolysis gas with higher heat value, wide ignition limit and lower ignition energy under the condition of lower environmental temperature so as to improve the cold starting performance of the engine.

3. The invention obtains the methanol cracking gas with higher heat value, wide ignition limit, lower ignition energy and relative cleanness in a short time by carrying out catalytic cracking on the evaporated methanol liquid, mixes the methanol steam which is not cracked in the cracking gas preparation device and the carbon monoxide and the hydrogen which are generated after cracking, and outputs the mixture to the engine so as to realize the low-temperature cold start work of the engine.

4. The method adopts multi-stage injection methanol for single ignition under the condition of cold start, can prepare relatively clean methanol pyrolysis gas with higher heat value, wide ignition limit and lower ignition energy under the condition of lower environmental temperature, and leads the methanol pyrolysis gas and the un-cracked methanol gas into the engine together to realize the quick cold start of the pure methanol engine, and the methanol cracking requires a time period with low energy consumption, does not need special heating parts, and has high stability and simple and convenient operation.

Drawings

Fig. 1 is a schematic structural diagram of a cold start device of a multi-stage injection methanol engine.

In all the figures, the same reference numerals denote the same features, in particular: 1-a first air inlet channel, 2-a first-stage methanol injector, 3-a spark plug, 4-a combustion chamber, 5-a second-stage methanol injector, 6-an evaporation and cracking chamber, 7-a screen, 8-a catalyst, 9-an exhaust pipe, 10-a methanol tank, 11-a methanol pump, 12-a methanol high-pressure oil rail, 13-a controller and 14-a vehicle-mounted battery.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Fig. 1 is a schematic structural diagram of a cold start device of a multi-injection methanol engine according to an embodiment of the present invention, where the cold start device includes a methanol evaporation and cracking module and a methanol multi-injection and ignition module. The methanol multi-stage injection and ignition module comprises a first-stage methanol injector 2, a spark plug 3, a second-stage methanol injector 5, a methanol tank 10, a methanol pump 11, a methanol high-pressure oil rail 12, a controller 13 and a vehicle-mounted battery 14. The methanol evaporation and cracking module comprises a first air inlet channel 1, a combustion chamber 4, an evaporation and cracking chamber 6, a screen 7, a catalyst 8 and an exhaust pipe 9.

The methanol tank 10 is connected with the methanol high-pressure oil rail 12 through a methanol pump 11, and the methanol pump 11 is used for inputting the methanol liquid stored in the methanol tank 10 into the methanol high-pressure oil rail 12. The methanol high-pressure oil rail 12 comprises a first-stage methanol injector 2 and a second-stage methanol injector 5, the first-stage methanol injector 2 is connected with the controller 13 through a first electromagnetic valve, the second-stage methanol injector 5 is connected with the controller 13 through a second electromagnetic valve, the controller 13 is powered by a vehicle-mounted battery 14 connected with the controller 13, the methanol pump 11 is used for inputting methanol liquid stored in the methanol tank 10 into the methanol high-pressure oil rail 12, and under the control action of the controller 13, the corresponding first electromagnetic valve and the corresponding second electromagnetic valve are opened, so that multi-stage methanol injection and single ignition are realized.

Further, in methyl alcohol evaporation and schizolysis module, first intake duct 1 with combustion chamber 4 is connected, combustion chamber 4 through the second intake duct with evaporation and schizolysis 6 are connected, evaporation and schizolysis 6 be connected with blast pipe 9 is connected. Wherein, spark plug 3 with one-level methyl alcohol sprayer 2 locates in the first intake duct 1, just spark plug 3 locates the one side that is close to combustion chamber 4, and one-level methyl alcohol sprayer 2 locates the one end of keeping away from combustion chamber 4 to when realizing letting in gas at first intake duct, controller 13 control one-level methyl alcohol sprayer 2's solenoid valve is opened and is sprayed methyl alcohol and air mixing earlier, forms rich mellow wine gas mixture in spark plug 3 department, and simultaneously, spark plug 3 ignites, and controller 13 control 3 ignition time of spark plug and then accomplish the work of lighting the gas mixture, and the gas mixture is through insufficient burning in combustion chamber 4, releases a large amount of heats simultaneously. The evaporation and cracking chamber 6 comprises a screen 7 and a catalyst 8 which are arranged in the evaporation and cracking chamber 6, the second-stage methanol injector 5 is arranged at the air inlet end of the evaporation and cracking chamber 6 and is arranged at one end close to the combustion chamber 4, the second-stage methanol injector 5 opens a second electromagnetic valve under the action of the controller 13 to inject liquid methanol into the evaporation and cracking chamber 6, the controller 13 controls the electromagnetic valve of the first-stage methanol injector 2 to open and inject methanol and air to be mixed, alcohol-rich mixed gas is formed at the spark plug 3, the controller 13 controls the ignition time of the spark plug 3 to further complete the work of igniting the mixed gas, the mixed gas is insufficiently combusted in the combustion chamber 4, and meanwhile, a large amount of heat is released, and the released heat is brought into the evaporation and cracking chamber 6 by airflow. Meanwhile, the second-stage methanol injector 5 opens the electromagnetic valve to inject methanol under the action of the controller 13, the methanol is heated and evaporated in the evaporation and cracking chamber 6 and then cracked on the surface of the catalyst to generate methanol cracking gas (hydrogen and carbon monoxide), wherein the uncracked methanol enters the engine through the exhaust passage.

Further, the methanol tank 10 is connected with a methanol pump 11 through a corrosion-resistant pipeline, and the methanol pump 11 is connected with a methanol high-pressure oil rail 12 through the corrosion-resistant pipeline.

Specifically, the primary methanol injector 2 is installed on the first intake port 1 in the direction in which the ignition plug 3 ignites. First intake duct 1 links to each other with combustion chamber 4, and spark plug 3 is installed and is close to 1 one end of first intake duct in combustion chamber 4, and the combustion chamber 4 other end links to each other with methyl alcohol evaporation and cracking chamber 6, evaporates and uses screen cloth 7 fixed methyl alcohol schizolysis catalyst 8 in the cracking chamber 6. The second-stage methanol ejector 5 is arranged at the air inlet end of the methanol evaporation and cracking chamber 6, and the other end of the methanol evaporation and cracking chamber 6 is connected with the exhaust pipe 9. In addition, the methanol tank 10 is connected with a methanol pump 11 through a corrosion-resistant pipeline, the methanol pump 11 is connected with a methanol high-pressure oil rail 12 through a corrosion-resistant pipeline, and the methanol high-pressure oil rail is connected with a methanol primary ejector 2 and a methanol secondary ejector 5.

At the time of cold start of the engine, air enters the apparatus through the first intake port 1 due to pumping action of the engine. Meanwhile, the methanol in the methanol tank 10 is made into high pressure flow by a corrosion-resistant pipeline through a methanol pump 11 and then flows through a methanol high pressure oil rail 12 to reach the primary methanol ejector 2 and the secondary methanol ejector 5. The controller 13 controls the electromagnetic valve of the primary methanol injector 2 to open and inject methanol first to mix with air (the injection angle is noticed, so as to avoid that the ignition can not be ignited by a wet spark plug). An alcohol-rich mixture is formed near the spark plug 3, the controller 13 controls the ignition timing of the spark plug 3 to complete the work of igniting the mixture, the mixture undergoes insufficient combustion in the combustion chamber 4, and simultaneously, a large amount of heat is released, and the released heat is carried by the gas flow into the methanol evaporation and cracking chamber 6. Meanwhile, the second-stage methanol injector 5 opens the electromagnetic valve to inject methanol under the action of the controller 13, the methanol is heated and evaporated in the evaporation and cracking chamber 6 and then cracked on the surface of the catalyst to generate methanol cracking gas, namely hydrogen and carbon monoxide, wherein the methanol which is not cracked enters the engine through the exhaust passage. As the hydrogen in the methanol pyrolysis gas has the characteristics of low minimum ignition energy, wide combustion range, high flame propagation speed, large diffusion coefficient and the like, the methanol pyrolysis gas is introduced into the cylinder of the automobile engine, so that the low-temperature cold start of the methanol engine is further promoted.

Further, the catalyst is a metal catalyst, and preferably, the metal catalyst is a copper-based catalyst such as a Cu — Cr catalyst, or a noble metal catalyst such as a Pt-based catalyst and a Pd-based catalyst.

A cold start method of a methanol engine with multi-stage injection comprises the following steps:

s1 starting the engine, enabling the first air inlet channel 1 to suck air, and meanwhile, controlling the primary methanol injector 2 to inject liquid methanol into the first air inlet channel 1 by the controller 13, wherein the air is mixed with the methanol to form an alcohol-rich mixed gas area in the first air inlet channel 1;

s2 the controller 13 controls the spark plug 3 to ignite in the rich alcohol gas mixture area, the methanol gas and the air are burnt in the combustion chamber 4, at the same time, a large amount of heat is released to form hot air flow;

the S3 controller 13 controls the secondary methanol injector 5 to inject liquid methanol into the evaporation and cracking chamber 6, the liquid methanol is mixed with hot air flow and evaporated into gaseous methanol under the heating action of the hot air flow, the gaseous methanol generates methanol cracking gas under the action of the catalyst 8, and then the methanol cracking gas enters the engine through the exhaust pipe 9 to promote the methanol engine to realize low-temperature cold start.

Further, in the step S1, the air-fuel ratio of the air to the methanol gas is 3.2:1 to 6.4: 1; in the step S3, the air-fuel ratio of the air entering the engine and the liquid methanol injected into the evaporation and cracking chamber 6 by the secondary methanol injector 5 is 3.2:1-6.4:1, and the methanol gas not cracked in the step S3 enters the engine through the exhaust pipe 9 to further promote the methanol engine to realize low-temperature cold start.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A methanol engine cold starting device with multi-stage injection comprises a methanol evaporation and cracking module and a methanol multi-stage injection and ignition module, wherein,

the methanol evaporation and cracking module comprises a first air inlet channel (1), a combustion chamber (4), an evaporation and cracking chamber (6) and an exhaust pipe (9) which are sequentially connected, the evaporation and cracking chamber (6) further comprises a catalyst (8) arranged in the evaporation and cracking chamber, and the tail end of the exhaust pipe (9) is connected with an air inlet of an engine; the methanol multi-stage injection and ignition module comprises a methanol tank (10), a methanol high-pressure oil rail (12), a methanol pump (11), a first-stage methanol injector (2), a second-stage methanol injector (5), a spark plug (3) and a controller (13), wherein the methanol tank (10) is connected with the methanol high-pressure oil rail (12) through the methanol pump (11), the methanol high-pressure oil rail (12) is respectively connected with the first-stage methanol injector (2) and the second-stage methanol injector (5), the spark plug (3) and the first-stage methanol injector (2) are arranged in the first air inlet channel (1), the first-stage methanol injector (2) is arranged on one side far away from the combustion chamber (4), the spark plug (3) is arranged on one side near the combustion chamber (4), the second-stage methanol injector (5) is arranged at the air inlet end of the evaporation and cracking chamber (6), the controller (13) is respectively connected with the first-stage methanol injector (2), the second-stage methanol injector (5) and the spark plug (3) and is used for controlling the injection quantity of the first-stage methanol injector (2) and the second-stage methanol injector (5) and the ignition time of the spark plug (3) so as to realize multi-stage injection and single ignition;

the cold starting device performs cold starting according to the following steps:

s1, starting the engine, enabling the first air inlet channel (1) to suck air, and meanwhile, controlling a primary methanol injector (2) to inject liquid methanol into the first air inlet channel (1) by a controller (13), wherein the air is mixed with the methanol to form an alcohol-rich mixed gas area in the first air inlet channel (1);

s2 the controller (13) controls the spark plug (3) to ignite in the rich alcohol mixed gas area, the injected methanol and air are burnt in the combustion chamber (4), and simultaneously, a large amount of heat is released to form hot air flow;

the S3 controller (13) controls the secondary methanol injector (5) to inject liquid methanol into the evaporation and cracking chamber (6), the liquid methanol is mixed with hot air flow and evaporated into gaseous methanol under the heating action of the hot air flow, the gaseous methanol generates methanol cracking gas under the action of the catalyst (8), so that high-temperature mixed gas containing the methanol cracking gas is formed, and the high-temperature mixed gas enters the engine through the exhaust pipe (9) to promote the methanol engine to realize low-temperature cold start.

2. A cold start device of a methanol engine as claimed in claim 1, characterized in that the first stage methanol injector (2) is provided with a first solenoid valve, the first solenoid valve is connected with the controller (13), the second stage methanol injector (5) is provided with a second solenoid valve, and the second solenoid valve is connected with the controller (13).

3. The cold start device of a methanol engine as claimed in claim 1 or 2, characterized in that the spark plug (3) is arranged in an alcohol-rich mixed gas area formed by the liquid methanol injected by the primary methanol injector (2) and air.

4. The methanol engine cold start device of claim 1, wherein the catalyst is a metal catalyst.

5. A methanol engine cold start device according to claim 1, characterized in that the methanol tank (10) is connected with a methanol pump (11) by corrosion resistant piping, and the methanol pump (11) is connected with the methanol high pressure oil rail (12) by corrosion resistant piping.

6. The methanol engine cold start device according to claim 1, wherein the methanol multi-stage injection and ignition module further comprises an on-board battery (14), and the on-board battery (14) is connected with the controller (13).

7. A methanol engine cold start device according to claim 1, characterized in that the evaporation and cracking chamber (6) further comprises a screen (7) provided inside it, the screen (7) being used to fix the catalyst (8).

8. The methanol engine cold start device according to claim 1, wherein in the step S1, the air-fuel ratio of the air to the methanol is 3.2:1 to 6.4: 1; in the step S3, the air intake quantity of the engine and the air-fuel ratio of the liquid methanol injected by the secondary methanol injector (5) are 3.2:1-6.4: 1.

9. The cold start device of a methanol engine as claimed in claim 1, wherein the methanol not cracked in S3 enters the engine through the exhaust pipe (9) to further promote the low temperature cold start of the methanol engine.