WO2016026375A1

WO2016026375A1 - Natural gas engine combustion method and supercharged natural gas engine using same

Info

Publication number: WO2016026375A1
Application number: PCT/CN2015/085610
Authority: WO
Inventors: 韩志玉
Original assignee: 江苏上淮动力有限公司
Priority date: 2014-08-19
Filing date: 2015-07-30
Publication date: 2016-02-25
Also published as: CN104213976A; CN104213976B

Abstract

Provided are a natural gas engine combustion method and supercharged natural gas engine using the same, combusting natural gas or other gas fuel with methane as a main component. The engine comprises a cylinder body, a cylinder cover, a piston, a crank-link mechanism, a gas inlet system, a gas exhaust system, a gas burning system, an ignition system, an engine controller and the like. The gas inlet system and the gas exhaust system are provided with an exhaust gas turbocharger thereon, the exhaust gas turbocharger consisting of a turbine and a compressor. The gas system comprises a gas injector installed on the cylinder cover or an inlet manifold, and gas is injected into a gas inlet channel through the gas injector. The supercharged natural gas engine can greatly improve dynamic performance and thermal efficiency at lower manufacturing costs.

Description

Specification t Ming Ming: Natural gas engine combustion method and pressurized natural gas using the method

Technical field

[0001] The present invention relates to the field of engine technology, and in particular to a natural gas engine combustion method and a pressurized natural gas engine using the same.

Background technique

[0002] The development of the automotive and engine industries has led to a significant increase in oil consumption and an increasing severity of exhaust pollution, which has constrained economic development, environmental and human health. The theory and practice show that the natural gas octane number is high and the antiknock performance is good; the molecular carbon to carbon ratio is low, so the C02 emission is low after combustion; the combustion characteristics are good, so the engine burning natural gas can save the petroleum liquid fuel and reduce the harmful emissions of the exhaust gas and Carbon dioxide, improving urban PM2.5 and reducing its contribution to the environmental greenhouse effect, is conducive to energy conservation and environmental protection.

[0003] One method currently used by automobiles to burn natural gas is gasoline-gas dual fuel technology. This technology allows the car engine to have the same ability to burn gasoline and natural gas, that is, the car is loaded with two fuel supply systems, gasoline and natural gas, and the same engine can selectively use gasoline or natural gas. In this case, the engine intake is naturally aspirated, and the natural gas enters the cylinder from the intake port (tube). Since the natural gas occupies the volume of the intake air, the engine charging efficiency is greatly reduced, resulting in a decrease in engine output torque and power. %~20<3⁄4. In addition, the gasoline-natural gas dual-fuel engine is designed according to the characteristics of gasoline. The design parameters of the engine, such as compression ratio and gas distribution, cannot best reflect the fuel characteristics of natural gas. The advantage of good natural gas explosion resistance cannot be fully exerted. The engine's natural gas consumption is better than its natural thermal efficiency (fuel consumption rate). In addition, the gasoline-gas dual-fuel vehicle has two sets of fuel systems, which makes the structure of the car complicated and costly.

[0004] In order to solve the shortcomings of the engine charging efficiency caused by the supply of natural gas from the intake port (or the intake manifold), a technical concept of directly injecting natural gas into the engine cylinder with a higher pressure (10 to 20 MPa) has also been proposed. . However, these concepts will face the following problems in the application: First, in the engine high-speed and large load, it is difficult to form a uniform mixture in the cylinder, resulting in a decrease in engine power performance (especially maximum power); The pressure of the gas cylinder is reduced, in order to ensure the supply of natural gas, natural The initial squirt and injection duration of the gas injection will be adjusted accordingly, resulting in different pressure and temperature of the engine under the same working condition. The engine is unreliable and has problems. The third is the requirement for natural gas storage tank. The gas storage pressure is much higher than the current 20MPa, which greatly increases the manufacturing cost and safety hazard of the gas storage tank.

[0005] In the meantime, in order to reduce the fuel consumption of natural gas, lean combustion is also used, that is, the engine draws in excess of chemical equivalent excess air. This technology is used in current power generation engines and medium and heavy medium and low speed diesel engines (engine speed). There are more applications on <3000 rpm). However, the use of lean burns on high-speed automotive engines leads to further reductions in engine power performance. In addition, in order to meet more stringent vehicle exhaust emission regulations, special NOx post-treatment devices must be used, resulting in more complex vehicle structures, manufacturing and Operating costs have increased.

technical problem

The present invention provides a natural gas engine that solves high-speed engines (usually used as automotive power) to burn natural gas or other methane-based gaseous fuels (eg, coalbed methane, shale gas, and hydrocarbon hydrate gas). Etc.) Technical issues of dynamic performance (torque and power) and low thermal efficiency. By adopting the technology of the invention, the power performance and thermal efficiency of the above engine can be greatly improved at a low cost, so that the dynamic performance significantly exceeds the power performance level of the engine burning gasoline or diesel crucible, and the natural gas and other methane gas are utilized more effectively. Resources.

Problem solution

Technical solution

The present invention provides a natural gas engine combustion method comprising the following steps:

[0008] Sl, natural gas is injected into the engine intake port under a pressure of 0.2-0.9 MPa, mixed with air, and enters the engine cylinder, and further mixed with air to form a uniform air-natural gas mixture;

[0009] S2, a mixture of excess air coefficient of 0.85~1.1, after compression of the engine piston with a compression ratio of 11.0~13.0, when the piston approaches the top dead center 吋, the spark generated by the spark plug ignites and burns, and the mixed gas passes through combustion And after expanding, pushing the piston to work, and then exhausting the engine cylinder;

[0010] S3. Exhaust gas enters the turbine of the exhaust gas turbocharger through the exhaust pipe, and drives the turbine to rotate and drives the connected compressor. Then, the exhaust gas enters the three-way catalytic converter reaction, and finally the exhaust gas is discharged to the atmosphere through the muffler. [0011] Further, the above natural gas may also be other gases containing methane as a main component, including coalbed methane.

, shale gas and hydrocarbon hydrate gas.

[0012] Further, the above-mentioned natural gas engine using the method has a maximum operating speed of 4000 to 8000 rpm, and the engine has a displacement per cylinder (working volume) of 0.6 liter or less.

[0013] The present invention provides a natural gas engine using the natural gas engine combustion method according to any one of the above, the natural gas engine including a cylinder block, a cylinder head, a piston, a crank linkage mechanism, an intake system, an exhaust system, and a gas a system, an ignition system, an engine controller, etc., wherein the intake system and the exhaust system are provided with an exhaust gas turbocharger, and the exhaust turbocharger is composed of a turbine and a compressor, and the turbine is connected to an exhaust pipe, The compressor is connected to the intake pipe, and the exhaust pipe is further provided with an oxygen sensor; the gas system includes a gas injector, the gas injector is mounted on the cylinder head or the intake pipe, and the gas is injected through the gas injector. airway.

[0014] Further, the air intake system further includes an air cleaner and a throttle.

[0015] Further, the gas system further includes a pressure regulating valve and a gas rail.

[0016] Further, the exhaust pipe of the exhaust system is further provided with a wastegate valve connected to the turbine.

[0017] further, the exhaust pipe is further provided with a three-way catalyst and a muffler, wherein the front and rear exhaust pipes of the three-way catalyst are provided with an oxygen sensor, and the oxygen sensor passes through the circuit and the engine controller Connected.

[0018] Further, a spark plug is disposed on the cylinder head, and at least one spark plug is installed in each cylinder.

[0019] The present invention also provides another natural gas engine provided with all of the components of the natural gas engine of any of the above, and an intercooler provided on the intake pipe. .

Advantageous effects of the invention

Beneficial effect

[0020] Compared with the prior art, the present invention provides a natural gas engine capable of greatly improving the dynamic performance and thermal efficiency of a natural gas engine.

Brief description of the drawing

DRAWINGS

1 is a schematic view of the mechanism of a pressurized natural gas engine of the present invention.

2 is a schematic view showing the mechanism of a supercharged natural gas engine with an intercooler according to the present invention.

[0023] FIG. 3 is a graph comparing the effective ratio fuel consumption. 4 is an effective torque comparison test diagram.

[0025] FIG. 5 is a graph of effective power comparison test. .

Embodiment 1 of the present invention

[0027] Natural gas engine (without intercooler), see Figure 1, a natural gas engine, including natural gas engine, cylinder head 9, piston, crank linkage, intake system, exhaust system, gas system , ignition system, engine controller 15, etc.

[0028] The exhaust system and the exhaust system are provided with an exhaust gas turbocharger 2, which is composed of a turbine 2b and a compressor 2a, the turbine 2b is connected to an exhaust pipe, and the compressor 2a and the intake pipe are connected 5-phase connection, exhaust pipe 1

An oxygen sensor 14 is also provided on the 1st.

[0029] The gas system includes a gas injector 8, and the gas injector 8 is mounted on the cylinder head 9 or on the intake pipe 5, and natural gas is injected into the intake port through the gas injector 8.

[0030] Preferably, the intake system further includes an air cleaner 1 and a throttle valve 4. The intake air is compressed by the compressor 2a and enters the cylinder. The throttle 4 is used to adjust the intake air amount of the engine to adjust the load of the engine.

[0031] Preferably, the gas system further includes a pressure regulating valve 6, a gas rail 7.

[0032] Preferably, the exhaust pipe 11 of the exhaust system is further provided with a wastegate valve 12 connected to the turbine.

[0033] Preferably, the exhaust pipe 11 is further provided with a three-way catalyst 13 and a muffler 16, and an oxygen sensor 14 is disposed on the front and rear exhaust pipes of the three-way catalyst, and the oxygen sensor 14 passes through the circuit and the engine controller. 15 connected.

[0034] Preferably, the cylinder head is provided with a spark plug, and each cylinder is provided with at least one spark plug.

Embodiment 2 of the present invention

[0036] Embodiment 2, a natural gas engine (with intercooler), in conjunction with Embodiment 1, see FIG. 2, another natural gas engine provided by the present invention, which is provided with the natural gas engine as described in Embodiment 1. In addition to all the components, an intercooler 3 is also included. In this arrangement, the intercooler 3 of the present invention cools the natural gas entering the engine, which helps to further improve the engine power performance.

Embodiment 3 of the present invention

[0038] Embodiment 3, a natural gas engine combustion method, referring to FIG. 1, and in combination with Embodiment 1 and Embodiment 2, the present invention provides a natural gas engine combustion method, comprising the following steps:

[0039] Sl, natural gas is injected into the engine intake port under a pressure of 0.2-0.9 MPa, mixed with air, and enters the engine cylinder, and further mixed with air to form a uniform air-natural gas mixture. [0040] S2, a mixture of excess air coefficient of 0.85~1.1, after compression of the engine piston with a compression ratio of 11.0~13.0, when the piston approaches the top dead center, the spark generated by the spark plug ignites and burns, and the mixed gas passes through the combustion. After the expansion, the piston is pushed to work, and then the exhaust gas is exhausted from the engine cylinder. The engine is burned with a stoichiometric mixing ratio. The excess air ratio of the mixture is 0.85~1.1, so that the mature and low-cost three-way catalyst can be used to treat the harmful components in the engine exhaust to meet the emission regulations.

[0041] S3. The exhaust gas enters the turbine 2b of the exhaust turbocharger 2 through the exhaust pipe 11, and pushes the turbine 2b to rotate and drives the connected compressor 2a. Then, the exhaust gas enters the three-way catalytic converter 13, and finally the exhaust gas is discharged to the atmosphere through the muffler.

[0042] Under certain operating conditions, part of the exhaust gas will not pass through the turbine 2b, but directly enters the three-way catalyst 13 through the wastegate valve 12. In the three-way catalytic converter 13, the harmful gases such as carbon monoxide (CO), nitrogen oxides (NOx), and hydrocarbons (HC) in the exhaust gas are chemically converted into carbon dioxide (C02) and nitrogen (N2). gas. In order to ensure that the three-way catalyst 13 operates at a higher conversion efficiency, the mixed gas should be burned as much as possible at a stoichiometric mixing ratio (excess air ratio of 1.0). An oxygen sensor 14 mounted on the exhaust pipe will detect the oxygen content of the exhaust gas and feed it back to the controller of the engine 15, which will adjust the natural gas jet volume accordingly to ensure the desired air-fuel ratio of the mixture. The exhaust gas is finally discharged to the ambient atmosphere through the muffler 16.

Preferably, the method is used to burn natural gas, and other gases containing methane as a main component, including coalbed methane, shale gas, and hydrocarbon hydrate gas, may also be used.

Preferably, the natural gas engine using the method has a maximum operating speed of 4000 to 8000 rpm, and the engine has a displacement per cylinder (working volume) of less than or equal to 0.6 liters.

Embodiment 4 of the present invention

[0046] The comparative test of the embodiment 4, please refer to FIG. 2, and the comparative test is carried out in combination with the embodiment 2 and the embodiment 3. The same as the following, the natural gas engine in the embodiment adopts the intercooler 3 of the embodiment 2. The natural gas engine, the prior art 1.2L gasoline-natural gas dual fuel engine of the fourth embodiment is an existing commercially available engine, and the performance data is the arithmetic of the data measured by all available prior art engines. average value. For ease of explanation, the following description of the gasoline-gas dual fuel engine burning natural gas is referred to as a dual fuel natural gas engine.

[0047] 4.1.1 Effective ratio fuel consumption comparison test Prior art 1.2L dual fuel natural gas engine (CNG) and pressurized natural gas engine (CNG) of the present invention

- Boost) The effective specific fuel consumption comparison test is shown in Figure 3.

[0049] As can be seen from FIG. 3, the supercharged natural gas engine of the present invention has a lower effective fuel consumption ratio, can effectively reduce the use cost of the automobile, and has an extremely broad market prospect.

[0050] 4.1.2 Effective Torque Comparison Test

Prior Art 1.2L dual fuel natural gas engine (CNG) and pressurized natural gas engine of the invention (CNG)

- Boost) The effective torque comparison test is shown in Figure 4.

[0052] With reference to FIG. 3, it can be seen from FIG. 4 that the turbocharged natural gas engine of the present invention has lower effective fuel consumption than the prior art dual fuel natural gas engine, and the effective torque of the engine at different rotational speeds. It is much higher than the prior art dual fuel natural gas engine. Thus, the pressurized natural gas engine provided by the present invention has better dynamic performance.

[0053] 4.1.3 Effective Power Comparison Test

Prior Art 1.2L Dual Fuel Natural Gas Engine (CNG) and the pressurized natural gas engine of the present invention (CNG)

- Boost) The results of the effective power comparison test are shown in Figure 5.

3 and FIG. 4, it can be seen from FIG. 5 that the turbocharged natural gas engine of the present invention has a lower effective fuel consumption than the prior art dual fuel natural gas engine, and the engine is effective at different rotational speeds. Torque, effective power is higher than prior art dual fuel natural gas engines.

The present invention has been described in the above preferred embodiments, but it is not intended to limit the invention, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention should be determined by the scope defined by the claims of the present invention.

Claims

Claim

[Claim 1] A natural gas engine combustion method, characterized in that the natural gas engine burning enthalpy using the method comprises the following steps:

51. Natural gas is injected into the engine intake port under the pressure of 0.2~0.9 MPa, mixed with air, and enters the engine cylinder, and further mixed with air to form a uniform air-natural gas mixture;

52. The mixture with an excess air ratio of 0.85~1.1 is compressed by the engine piston with a compression ratio of 11.0~13.0. When the piston approaches the top dead center, the spark generated by the spark plug ignites and burns. After the mixture is burned and expanded, Pushing the piston to work, and then exhausting the engine cylinder;

53. Exhaust gas enters the turbine of the exhaust turbocharger through the exhaust pipe, pushes the turbine to rotate and drives the connected compressor, and then the exhaust gas enters the three-way catalytic converter reaction, and finally the exhaust gas is discharged to the atmosphere through the muffler.

[Claim 2] The natural gas engine combustion method according to claim 1, wherein the natural gas may be other gas containing methane as a main component, including coalbed methane, shale gas, and hydrocarbon hydrate gas. Wait.

[Claim 3] The natural gas engine combustion method according to claim 1, wherein the natural gas engine using the method has a maximum operating speed of 4000 to 8000 rpm, and the displacement per cylinder of the engine is less than or equal to 0.6 liters.

[Claim 4] The natural gas engine using the natural gas engine combustion method according to any one of claims 1 to 3, wherein the natural gas engine includes a cylinder block, a cylinder head, a piston, a crank link mechanism, and an intake air System, exhaust system, gas system, ignition system, engine controller, etc.

An exhaust gas turbocharger is disposed on the intake system and the exhaust system, the exhaust turbocharger is composed of a turbine and a compressor, and the turbine is connected to an exhaust pipe, and the compressor and the intake pipe are connected Connecting, the exhaust pipe is further provided with an oxygen sensor;

The gas system includes a gas injector that is mounted on a cylinder head or on an intake manifold through which gas is injected into the intake passage.

[Claim 5] The natural gas engine according to claim 4, wherein the intake system further includes an air cleaner and a throttle.

[Claim 6] The natural gas engine according to claim 4, wherein the gas system further comprises a pressure regulating valve, gas

rail.

[Claim 7] The natural gas engine according to claim 4, wherein the exhaust pipe of the exhaust system is further provided with a wastegate valve connected to the turbine.

[Claim 8] The natural gas engine according to claim 4, wherein the exhaust pipe is further provided with a three-way catalyst and a muffler, and the front and rear exhaust pipes of the three-way catalyst are provided An oxygen sensor, the oxygen sensor being coupled to the engine controller via a circuit.

[Claim 9] The natural gas engine according to claim 4, wherein a spark plug is provided on the cylinder head, and at least one spark plug is installed in each cylinder.

[Claim 10] A natural gas engine characterized by being provided with all the components of the natural gas engine according to any of claims 4-9, and an intercooler provided on the intake pipe.