Control strategy for an engine
阅读说明:本技术 发动机的控制策略 (Control strategy for an engine ) 是由 苏博浩 常进才 王一望 曹思雨 屈伟 张鹏 韩桂苓 王怡玺 王伟强 吕胜国 张期 于 2019-02-22 设计创作,主要内容包括:本发明公开了一种发动机的控制策略,所述发动机包括:缸体、催化器以及燃油喷射系统,所述燃油喷射系统适于朝向所述缸体内供给燃油,且所述燃油喷射系统为中置直喷式燃油喷射系统;其中所述控制策略至少包括以下步骤:S1:燃油喷射系统进行第一次燃油喷射;S2:在所述发动机完成压缩行程后,燃油喷射系统进行第二次燃油喷射;S3:在第二次燃油喷射完毕后,发动机点火。这样,可以提高燃烧稳定性,使燃油燃烧更加充分,从而提高发动机的工作稳定性,并降低碳氧化合物以及氮氧化合物的排放。(The invention discloses a control strategy for an engine, the engine comprising: the fuel injection system is suitable for supplying fuel into the cylinder and is a middle direct injection type fuel injection system; wherein the control strategy comprises at least the steps of: s1: the fuel injection system performs first fuel injection; s2: after the engine finishes a compression stroke, performing secondary fuel injection by the fuel injection system; s3: after the second fuel injection is completed, the engine is ignited. Therefore, the combustion stability can be improved, fuel oil can be more fully combusted, the working stability of the engine is improved, and the emission of carbon oxides and nitrogen oxides is reduced.)
1. A control strategy for an engine (1000), the engine (1000) comprising: a cylinder block and a catalyst (100); a fuel injection system (200), said fuel injection system (200) being adapted to supply fuel into said cylinder, and said fuel injection system (200) being a mid-direct injection fuel injection system (200); wherein
The control strategy comprises at least the following steps:
s1: the fuel injection system (200) performs a first fuel injection;
s2: after the engine (1000) completes a compression stroke, the fuel injection system (200) performs a second fuel injection;
s3: after the second fuel injection is completed, the engine (1000) is ignited.
2. The control strategy of an engine (1000) according to claim 1, characterized in that the determination conditions of the first fuel injection are: the injection is performed when the engine (1000) is in an intake stroke and a crank angle of the engine (1000) is 260-280 ℃.
3. The engine (1000) control strategy of claim 1, wherein the pulse width of the second fuel injection is 0.25ms-0.30 ms.
4. A control strategy for an engine (1000) according to claims 1-3, characterized in that the second fuel injection has an injection complete time t1 and the engine (1000) ignition has an ignition time t2, t1 ≦ t 2.
5. A control strategy for an engine (1000) according to claim 4, characterized in that the engine (1000) is spark-retarded, the ignition time is a retarded ignition time, and the range of angles from which the angle of the ignition advance is retarded is: -25 ℃ A-40 ℃ A.
6. The engine (1000) control strategy of claim 1 further comprising a cylinder head (300), said cylinder head (300) being a dual-flow head (300), said cylinder head (300) having an exhaust manifold integrated thereon.
7. The engine (1000) control strategy of claim 6, further comprising an oxygen sensor (400) and a turbocharger (500) that can rapidly achieve closed-loop control, wherein the closed-loop time of the oxygen sensor (400) is not greater than 7 s.
8. A control strategy for an engine (1000) according to claim 7, characterized in that the turbocharger (500) is provided with a wastegate valve (600), the maximum opening of the wastegate valve (600) being not less than 40 °, the axis of the turbine of the turbocharger (500) being not less than 120 ° to the axis of the catalyst (100).
9. The engine (1000) control strategy of claim 1, wherein the catalyst (100) comprises:
a catalyst carrier (110), wherein a first region (111) and a second region (112) which are connected in sequence are formed on the catalyst carrier (110); and
a first metal coating (120), the first metal coating (120) having a total amount of first metal of G, the first area (111) being uniformly coated with 0.6G-0.8G of the first metal, the second area (112) being uniformly coated with 0.2G-0.4G of the first metal;
a second metal coating (130), the second metal coating (130) being uniformly coated on the first metal coating (120).
10. The control strategy of an engine (1000) according to claim 9, characterized in that the length of the catalyst carrier (110) is L and the length of the first zone (111) ranges from: 0.3L-0.4L; the length range of the second region (112) is: 0.6L-0.7L.
Technical Field
The invention relates to the technical field of vehicles, in particular to a control strategy of an engine.
Background
Disclosure of Invention
In view of the above, the present invention is directed to a control strategy.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
a control strategy for an engine, said engine comprising: the fuel injection system is suitable for supplying fuel into the cylinder and is a middle direct injection type fuel injection system; wherein the control strategy comprises at least the steps of: s1: the fuel injection system performs first fuel injection; s2: after the engine finishes a compression stroke, performing secondary fuel injection by the fuel injection system; s3: after the second fuel injection is completed, the engine is ignited.
Further, the determination conditions of the first fuel injection are: the injection is performed when the engine is in an intake stroke and a crank angle of the engine is 260-280 CA.
Further, the pulsewidth of the second fuel injection is 0.25ms to 0.30 ms.
Further, the second fuel injection has an injection completion timing t1, and the engine ignition has an ignition timing t2, t1 ≦ t 2.
Further, the engine is a delayed ignition, the ignition time is delayed ignition time, and the angle range in which the angle of the ignition advance angle corresponding to the ignition time is delayed is as follows: -25 ° CA-40 ° CA.
Further, the engine also comprises a cylinder cover, wherein the cylinder cover is a double-channel cylinder cover, and an exhaust manifold is integrated on the cylinder cover.
Further, the engine also comprises an oxygen sensor and a turbocharger which can realize closed-loop control rapidly, and the closed-loop time of the oxygen sensor is not more than 7 s.
Further, the turbocharger is provided with a waste gas bypass valve, the maximum opening degree of the waste gas bypass valve is not smaller than 40 degrees, and the included angle between the axis of the turbine of the turbocharger and the axis of the catalyst is not smaller than 120 degrees.
Further, the catalyst includes: the catalyst comprises a catalyst carrier, a first metal coating and a second metal coating, wherein a first area and a second area which are sequentially connected are formed on the catalyst carrier; the total amount of the first metal coating is G, the first area is uniformly coated with 0.6G-0.8G of the first metal, and the second area is uniformly coated with 0.2G-0.4G of the first metal; the second metal coating is uniformly coated on the first metal coating.
According to some embodiments of the invention, the catalyst carrier has a length L, and the first region has a length in a range of: 0.3L-0.4L; the length range of the second area is as follows: 0.6L-0.7L.
The control strategy of the engine is matched, and the following advantages are achieved:
(1) in the control strategy direction, the control on the exhaust emission is realized through reasonable secondary injection selection, the rotating speed and the torque of the engine do not need to be improved in the control strategy direction, the problems of high noise and vibration of the engine and the like do not occur, and the use experience of customers can be effectively improved;
(2) the ignition advance angle can be retarded by a large angle, so that higher exhaust temperature is generated, and the catalyst can be quickly ignited;
(3) the arrangement of the middle direct injection type fuel injection system ensures that the second fuel injection is more matched with the delayed ignition advance angle, so that the control of the ignition time and the fuel injection time of the second injection is more accurate;
(4) when the engine is in cold start, the heat dissipation of the exhaust channel and the cylinder cover is less, so that the residual exhaust gas backflow is reduced, and the catalyst can be heated by the exhaust gas more quickly;
(5) the closed-loop time of the oxygen sensor is short, and the emission of hydrocarbons and nitrogen oxides generated before the closed-loop of the oxygen sensor is high, namely the emission limit value is exceeded before the catalyst is ignited;
(6) the maximum opening angle of the waste gas bypass valve is large, more waste gas can be discharged to the catalyst through the waste gas bypass valve in the starting stage, so that more waste gas with higher temperature can participate in the heating process of the catalyst, the catalyst can be heated more quickly, heat accumulation in a turbine can be reduced, and the working environment of the turbine can be effectively improved;
(7) the included angle between the axis of the catalytic converter and the axis of the turbocharger turbine is larger, so that the energy loss generated when the waste gas passes through the bent wall surface can be reduced;
(8) the catalyst coating is designed to be a noble metal double-layer coating, and the noble metal coating is designed in a targeted manner according to the internal reaction of the catalyst, so that the conversion efficiency is lower; meanwhile, the ratio of the specification length to the diameter of the catalytic converter is reasonable, gas flowing into the catalytic converter is more uniform, and the catalytic performance is higher;
(9) the control on nitrogen oxide and carbon oxide in the waste gas is more effective, the emission test with higher requirements can be met, and harmful compounds in the tail gas emitted in daily use can be effectively reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic illustration of a catalyst according to an embodiment of the present invention;
FIG. 2 is a schematic view of a portion of a catalyst according to an embodiment of the invention;
FIG. 3 is a schematic illustration of an engine according to an embodiment of the present invention;
FIG. 4 is a graphical illustration of catalyst light-off, conversion, and time;
FIG. 5 is a graph showing the total amount of carbon oxides and nitrogen oxides emitted as a function of time;
FIG. 6 is a time line schematic of a control strategy for an engine;
FIG. 7 is a graphical illustration of pulse width for a second fuel injection versus cycle ripple rate for a control strategy for an engine;
FIG. 8 is a graphical representation of noble metal coating density versus hydrocarbon conversion;
FIG. 9 is a flow chart of a control strategy for an engine.
Description of reference numerals:
1000-the engine of the engine, wherein,
100-catalyst, 200-fuel injection system, 300-cylinder head, 400-oxygen sensor, 500-turbocharger, 600-waste gate valve,
110-catalyst support, 111-first region, 112-second region, 120-first metal coating, 130-second metal coating;
length of the L-catalyst, width or diameter of the D-catalyst;
a-intake Top Dead Center (TDC), b-intake stroke (suction), c-intake Bottom Dead Center (BDC), d-compression stroke (compression), e-first fuel injection, f-second fuel injection, g-ignition timing.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
As shown in fig. 1 to 9, according to the control strategy of the
Wherein the control strategy at least comprises the following steps:
s1: the
s2: after the
s3: after the second fuel injection is completed, the
Specifically, the mid-point direct injection belongs to an injection guiding concept, and compared with a wall surface guiding and air guiding concept of side-point direct injection or manifold injection, the fuel injection control is more accurate, especially, the coupling control of a smaller injection pulse width (shorter injection time) and an ignition time is more accurate, so that the accuracy of the second fuel injection of the embodiment can be higher, the cycle fluctuation rate boundary is maximized, the ignition advance angle is delayed to the maximum extent, the combustion stability of the fuel in the
According to the control strategy of the
Further, the determination conditions for the first fuel injection are: injection is performed when
Specifically, the 260 ° CA-280 ° CA range refers to: the first fuel injection can make the fuel and air mix more evenly in the 260 CA-280 CA (i.e. crank angle) range of the intake stroke, and the equivalence ratio combustion is performed, and at the same time, the angular range of the 260 CA-280 CA range is lower in the rotation speed ratio of the
Therefore, the first fuel injection is selected in the middle of the intake stroke (see fig. 6) so that the fuel and the air can be sufficiently mixed.
And meanwhile, the first fuel injection is carried out when the crank angle is in the angle range, so that the turbulence generated by the fuel spray can be slowly attenuated, and the fuel and the air can be fully mixed when the first fuel injection is too early or too late (namely, the conditions that the turbulence begins to attenuate at the front end of a compression stroke and the oil-gas mixing is insufficient because the injection is too late are prevented).
In addition, the wet wall phenomenon of the inner wall of the combustion chamber caused by fuel spray can be caused, and the fuel splashed on the inner wall of the combustion chamber can be evaporated more quickly, so that the lowest exhaust emission and the engine oil dilution are ensured, namely, the control strategy of the embodiment can reduce other negative effects on the
As shown in fig. 6, the determination conditions for the second fuel injection are: injection is performed after
Thus, the injection timing of the second fuel injection takes into account that the initial flame generation occurs after the second fuel injection, making the fuel-air concentration in the region around the spark plug of the
Referring to fig. 7, the pulse width of the second fuel injection of the control strategy of the present embodiment is set to 0.25ms to 0.30 ms. Therefore, the pulse width of the second fuel injection is more reasonable, and the cyclic fluctuation rate COV% reaches the lowest value, so that the combustion of oil gas is more stable.
For example, taking the rotation speed of the
Further, the
It will be appreciated that retarding the ignition timing is effective to promote combustion and reduce hydrocarbon emissions, and therefore, control the spark advance to be in the range of-25 CA to-40 CA when the
And further, the cycle fluctuation rate is kept stable, combustion is more stable, and
That is, in order to prevent the influence of the second fuel injection on drivability, the second fuel injection is coupled to the ignition timing, so that turbulence generated by the first fuel injection can be improved or enhanced, the speed of flame propagation and diffusion can be increased, and combustion stability can be improved.
Further, the
Specifically, the
Thus, on one hand, exhaust interference can be effectively eliminated, residual exhaust gas is reduced from flowing back to the combustion chamber of the
Further, the
Further, the
It should be noted that the larger the opening degree of the
In addition, the supercharger is designed for a low heat capacity concept (i.e., the specific heat capacity of the housing of the turbine of the supercharger is low), so that the housing of the turbine of the supercharger can transfer more heat to the
As shown in fig. 3, the axis of the turbine of the
The included angle between the axis of the
As shown in fig. 1 and 2, the
Specifically, the
According to the
In the particular embodiment shown in fig. 2, the
Specifically, the
Referring to fig. 8, it is shown that when the conversion of hydrocarbon is highest, the coating ratio of Pd metal in the
Therefore, the length of the
In the particular embodiment shown in FIG. 1, the length of the
It is understood that, under the premise that the total volume of the
Therefore, in order to balance the catalytic performance and the backpressure, the
According to the control strategy of the
In summary, the
(1) in the control strategy direction, the control on the exhaust emission is realized through reasonable secondary injection selection, the rotating speed and the torque of the
(2) the spark advance can be retarded by a large angle, resulting in higher exhaust temperatures so that
(3) the arrangement of the middle direct injection type
(4) when the
(5) the
(6) the maximum opening angle of the
(7) the included angle between the axis of the
(8) the coating of the
(9) the control on nitrogen oxide and carbon oxide in the waste gas is more effective, the emission test with higher requirements can be met, and harmful compounds in the tail gas emitted in daily use can be effectively reduced.
As shown in fig. 1 and 2, in the
First, in terms of control strategy: the ignition time, the oil injection time and the oil injection frequency of the
Finally, the control strategy and the hardware configuration form a
Thus, referring to FIG. 1, the light-off temperature of
That is, in the test standard of SULEV20, 20 seconds before the FTP cycle is idle, and the
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
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