CN114810398A - Injection pressure and injection quantity coupling method for low-temperature operation stability of diesel engine - Google Patents
Injection pressure and injection quantity coupling method for low-temperature operation stability of diesel engine Download PDFInfo
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- CN114810398A CN114810398A CN202210456327.4A CN202210456327A CN114810398A CN 114810398 A CN114810398 A CN 114810398A CN 202210456327 A CN202210456327 A CN 202210456327A CN 114810398 A CN114810398 A CN 114810398A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/30—Controlling fuel injection
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Abstract
The invention discloses a method for coupling injection pressure and injection quantity of low-temperature operation stability of a diesel engine, and belongs to the technical field of diesel internal combustion engines. When the atmospheric temperature is lower than-20 ℃, the ignition and the stable operation of the diesel engine are ensured by adopting a method of reducing the injection pressure when supplying oil to the combustion chamber of the diesel engine and simultaneously increasing the injection concentration along with the reduction of the compression end temperature. The invention can ensure that the diesel engine can quickly and stably catch fire under the condition that the atmospheric temperature is lower than minus 20 ℃, and has good combustion efficiency.
Description
Technical Field
The invention belongs to the technical field of diesel internal combustion engines, and particularly relates to a control method for injection pressure and injection quantity for improving low-temperature operation stability of a diesel engine.
Background
The diesel engine has the advantages of high thermal efficiency, strong power output capability, good reliability and the like, and is widely applied to power sources of daily life and military equipment. But it is subject to unstable fires and large cyclic variations when operated in extremely cold environments (atmospheric temperatures below-20 ℃) with increased harmful emissions. Particularly, because the spray evaporation is slow at low temperature, the oil bundles are cooled after hitting the wall, and the probability of various unstable fires such as fire, intermittent fire, incomplete combustion and the like is greatly increased.
Generally, it is considered that under a high-temperature working condition with the compression top dead center temperature of 800K or more, the higher the injection pressure is, for example, the ultrahigh pressure injection of 200MPa or more, the better the super-atomization effect is, thereby facilitating stable ignition and thermal efficiency improvement. However, the experimental results show that the high injection pressure in the extremely cold environment is not favorable for stable ignition, and even greatly increases the probability of fire catching. Meanwhile, strong coupling effect exists between the injection pressure and the injection quantity, and if the cold and hot flames are difficult to smoothly transition under the conventional injection quantity with high injection pressure. It can be seen that in an extremely cold environment, a proper injection pressure needs to be determined, and meanwhile, the fuel injection quantity is adjusted to ensure rapid and stable ignition and obtain higher combustion efficiency.
Disclosure of Invention
In view of the above, the invention provides a method for coupling injection pressure and injection quantity of diesel engine with low-temperature operation stability, which can ensure that the diesel engine can quickly and stably catch fire under the condition that the atmospheric temperature is lower than-20 ℃, and has good combustion efficiency.
The injection pressure and fuel injection quantity coupling method for diesel engine low-temperature operation stability is characterized by that when the atmospheric temperature is less than-20 deg.C, along with the reduction of compression end temperature, the injection pressure when the fuel is supplied to combustion chamber of diesel engine is reduced and at the same time the fuel injection concentration is increased so as to ensure that the ignition and operation of diesel engine are stable.
Further, when the compression finishing temperature is 850K, the corresponding injection pressure is 80MPa, and the oil injection quantity is 10-20 mg.
Further, when the compression is finished to 800K, the corresponding injection pressure is 40MPa, and the oil injection quantity is 20-30 mg.
Further, when the compression finishing temperature is lower than 800K, the corresponding injection pressure is less than 40MPa, and the oil injection quantity is more than 30 mg.
Furthermore, the coupling method is suitable for a heavy-duty diesel engine with the orifice diameter of more than 0.2mm, the cylinder diameter of more than 90mm and the compression ratio of 13-18.
Has the advantages that:
1. according to the coupling control method, along with the reduction of the temperature at the end of compression, the ignition stability of the diesel engine is ensured by adopting a method of reducing the injection pressure when supplying oil to the combustion chamber of the diesel engine and increasing the oil injection concentration, although the influence of the oil injection quantity on the flame lag phase is small, the concentration of the mixed gas at the cold flame stage under the working condition of small oil injection quantity in a low-temperature environment is reduced, the hot flame cannot be smoothly transited, and the flame lag phase is greatly prolonged and even only weak cold flame is transiently transited to catch fire. Therefore, the fuel injection amount needs to be increased appropriately to ensure the normal transition of the cold flame and the hot flame, so as to ensure the stable ignition and the high combustion efficiency of the diesel engine.
2. According to the coupling control method, when the compression end temperature is 850K, the corresponding injection pressure is 80MPa, and the oil injection quantity is 10-20 mg; when the temperature is 850K, the stagnation period can be effectively shortened when the injection pressure is moderately increased to 80MPa, the ignition can be triggered even if the oil quantity is small when the oil injection quantity is 10-20mg, namely the low-temperature ignition limit is widened, and the quick ignition of the diesel engine and the ignition stability are improved after the two conditions are combined.
3. According to the coupling control method, when the compression end temperature is 800K, the corresponding injection pressure is 40MPa, and the oil injection quantity is 20-30 mg; in addition, when the compression finishing temperature is lower than 800K, the corresponding injection pressure is less than 40MPa, and the oil injection quantity is more than 30 mg; the lower the compression end temperature is, the stronger the necessity of the low-pressure enrichment injection strategy is, and the low-temperature ignition limit can be effectively expanded.
4. The coupling method is suitable for a heavy-duty diesel engine with the orifice diameter of more than 0.2mm, the cylinder diameter of more than 90mm and the compression ratio of 13-18; the diesel engine meeting the condition parameters can expand the ignition limit and improve the combustion efficiency after combined with the combined action of a low-pressure enrichment injection strategy.
Drawings
FIG. 1 is a schematic diagram illustrating the effect of injection pressure on flame development profile in an environment of 850K temperature;
FIG. 2 is a schematic diagram illustrating the influence of injection pressure on flame development pattern in an environment of 800K temperature;
FIG. 3 is a graph of the influence of fuel injection quantity on the combustion lag period in a low-temperature environment;
FIG. 4 is a distribution diagram of the area of the flame under the combined effect of injection pressure and injection quantity;
FIG. 5 is an image of a flame under the combined effect of injection pressure and injection quantity;
FIG. 6 is a distribution diagram of ignition area under different injection pressures and injection quantities.
Detailed Description
The invention is described in detail below by way of example with reference to the accompanying drawings.
The invention provides a coupling method of injection pressure and injection quantity of low-temperature operation stability of a diesel engine, which adopts a method of reducing the injection pressure and increasing the injection concentration when supplying oil to a combustion chamber of the diesel engine to ensure the ignition and the stable operation of the diesel engine along with the reduction of the compression end temperature when the atmospheric temperature is lower than-20 ℃. The coupling method of the present invention will be described in detail below by taking a heavy duty diesel engine having a nozzle hole diameter of 0.2mm or more, a cylinder diameter of 90mm or more, and a compression ratio of 13 to 18 as an example.
When the compression end temperature is 850K, the corresponding injection pressure is 80MPa, and the oil injection quantity is 10-20 mg.
When the compression is finished to 800K, the corresponding injection pressure is 40MPa, and the oil injection quantity is 20-30 mg.
When the compression end temperature is lower than 800K, the corresponding injection pressure is less than 40MPa, and the oil injection quantity is more than 30 mg.
As shown in fig. 1, when the injection pressure of the diesel engine is moderately increased at a higher ambient temperature, such as 850K, such as 80MPa, it can be seen from the flame development pattern in the figure that the stagnation period can be effectively shortened by increasing the injection pressure of the fuel, and as shown in fig. 2, when the ambient temperature is reduced, such as 800K, it can be seen from the flame development pattern in the figure that the injection pressure should be reduced to 40MPa to ensure stable ignition.
Fig. 3 is a graph of the influence of the fuel injection amount on the misfire period in a low-temperature environment, and although the ignition misfire period is almost the same in a large fuel injection amount range, the transition duration of the cold flame and the hot flame in the small fuel injection is greatly increased, the overall ignition is seriously delayed and the volatility is extremely high, so that the appropriate enrichment injection is required to ensure the stability of the ignition.
As shown in fig. 4 and 5, two ignition limits exist in the experimental surface working condition under the combined effect of the injection pressure and the injected fuel quantity, namely the limit between the yellow flame area and the blue flame area, and the limit between the blue flame area and the misfire area. A large cluster of stable white and yellow flames can be formed in the yellow flame area; only a small area of weak blue flame can be formed in the blue flame area; whereas flames are difficult to observe in the misfire area. As the injection pressure increases, at high (e.g., 50mg), low (e.g., 20mg) injection quantities, yellow flame to blue flame and blue flame to misfire, respectively. As the injected fuel amount decreases, the yellow flame shifts to the blue flame and the blue flame shifts to the misfire at low (e.g., 40MPa) and high (e.g., 100MPa) injection pressures, respectively.
As shown in fig. 6, the transition boundaries of different ignition regions depend on the coupling effect of injection pressure and injection quantity. When the injection pressure is 40-60MPa, yellow flame can be formed when the injection quantity is larger than the yellow line indicating oil quantity, the ignition is stable, and the working point is positioned in the third area; when the fuel injection quantity is larger than the blue line and is lower than the yellow line to indicate the fuel quantity, weak blue flame can be formed, the ignition is unstable, and the working point is located in the second area.
The minimum fuel injection amount required for stable ignition at an injection pressure of 40MPa was 25mg, and increased to 35mg at 60 MPa. However, at a higher injection pressure of 80-100MPa, yellow flames but only blue flames cannot be formed even if the injection quantity is increased (such as 50 mg). And under the injection pressure of 40-100MPa, flame can not be formed when the injected fuel quantity is less than the blue line indicated fuel quantity, namely, fire is generated, and the working point is positioned in the I area. The minimum injection quantity required for critical ignition increases approximately linearly as the injection pressure increases. Even a small amount of fuel at low injection pressures can trigger a fire, i.e. contribute to broadening the low temperature fire margin. The ignition is unstable under the injection pressure of 40MPa when the fuel injection quantity is 10mg, and the ignition can be stable even if the injection pressure is increased to 60MPa when the fuel injection quantity is 35mg, namely, the ignition and combustion can be optimized by properly increasing the injection pressure under the condition of large fuel injection quantity.
In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. The method for coupling injection pressure and injected fuel quantity of diesel engine with low-temp. operation stability is characterized by that when the atmospheric temp. is less than-20 deg.C, along with the reduction of compression end temp., the injection pressure when the fuel is supplied to combustion chamber of diesel engine is reduced, and at the same time the fuel injection concentration is increased so as to ensure that the diesel engine is ignited and stably operated.
2. The method for coupling the injection pressure and the fuel injection quantity of the diesel engine with the low-temperature operation stability as claimed in claim 1, wherein when the compression end temperature is 850K, the corresponding injection pressure is 80MPa, and the fuel injection quantity is 10-20 mg.
3. The method for coupling injection pressure and fuel injection quantity of diesel engine with low temperature operation stability as claimed in claim 2, wherein when the compression is finished to 800K, the corresponding injection pressure is 40MPa, and the fuel injection quantity is 20-30 mg.
4. The method for coupling injection pressure and fuel injection quantity of diesel engine with low temperature operation stability as claimed in claim 3, wherein when the compression end temperature is lower than 800K, the corresponding injection pressure is less than 40MPa, and the fuel injection quantity is greater than 30 mg.
5. The method for coupling the injection pressure and the injection quantity of the diesel engine with the low-temperature operation stability is characterized in that the method is suitable for a heavy-duty diesel engine with the orifice diameter of more than 0.2mm, the cylinder diameter of more than 90mm and the compression ratio of 13-18.
6. The method for coupling the injection pressure and the injection quantity of the diesel engine with the low-temperature operation stability is characterized in that the coupling method is suitable for a heavy diesel engine with the orifice diameter of more than 0.2mm, the cylinder diameter of more than 90mm and the compression ratio of 13-18.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210456327.4A CN114810398A (en) | 2022-04-27 | 2022-04-27 | Injection pressure and injection quantity coupling method for low-temperature operation stability of diesel engine |
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| CN202210456327.4A CN114810398A (en) | 2022-04-27 | 2022-04-27 | Injection pressure and injection quantity coupling method for low-temperature operation stability of diesel engine |
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Citations (4)
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| CN104265480A (en) * | 2014-08-25 | 2015-01-07 | 北京理工大学 | Starting fuel output control method of diesel under plateau environment |
| CN112146886A (en) * | 2020-09-10 | 2020-12-29 | 北京理工大学 | Method for determining oil injection pressure in low-temperature environment |
| CN112282956A (en) * | 2020-09-17 | 2021-01-29 | 潍柴动力股份有限公司 | Control method, device and system for diesel engine oil injection |
| CN112377319A (en) * | 2020-11-13 | 2021-02-19 | 北京理工大学 | Oil injection pressure control method for improving cold starting performance of diesel engine |
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- 2022-04-27 CN CN202210456327.4A patent/CN114810398A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104265480A (en) * | 2014-08-25 | 2015-01-07 | 北京理工大学 | Starting fuel output control method of diesel under plateau environment |
| CN112146886A (en) * | 2020-09-10 | 2020-12-29 | 北京理工大学 | Method for determining oil injection pressure in low-temperature environment |
| CN112282956A (en) * | 2020-09-17 | 2021-01-29 | 潍柴动力股份有限公司 | Control method, device and system for diesel engine oil injection |
| CN112377319A (en) * | 2020-11-13 | 2021-02-19 | 北京理工大学 | Oil injection pressure control method for improving cold starting performance of diesel engine |
Non-Patent Citations (3)
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| 石智成等: "冷起动工况柴油/煤油燃料喷雾燃烧特性研究", 《工程热物理学报》 * |
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