CN110748429A

CN110748429A - Control strategy for an engine

Info

Publication number: CN110748429A
Application number: CN201910133855.4A
Authority: CN
Inventors: 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; 张期鑫
Original assignee: Great Wall Motor Co Ltd
Current assignee: Great Wall Motor Co Ltd
Priority date: 2019-02-22
Filing date: 2019-02-22
Publication date: 2020-02-04
Anticipated expiration: 2039-02-22
Also published as: CN110748429B

Abstract

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.

Description

Control strategy for an engine

Technical Field

The invention relates to the technical field of vehicles, in particular to a control strategy of an engine.

Background

In the related art, the currently commonly adopted emission regulations (national sixth a/b, european sixth, SULEV20, etc.) cancel the warm-up time before sampling, and take cold start emission into account, wherein the severer SULEV20 further provides that the sum of hydrocarbons and nitrogen oxides does not exceed 20mg/mile during the whole FTP test cycle, and the current engine is generally realized by the following means for the emission problems of hydrocarbons and nitrogen oxides in the emission cycle in order to meet the emission regulations:

(1) adjusting an ECU control strategy: increasing the rotating speed of the engine; the engine torque is improved; the water temperature of the engine is improved; retarding the ignition advance angle; one or two injections.

(2) The oil injection system comprises: a central direct injection or side direct injection or intake manifold oil injection system; an exhaust system: a non-cylinder head integrated exhaust manifold or a cylinder head integrated exhaust manifold; oxygen sensor (closed loop time greater than 15 s); a supercharger (a waste gate valve has a small maximum opening angle and a high heat capacity); the catalyst is arranged (the included angle between the axis of the catalyst and the axis of the turbocharger is small); the catalyst specification (the ratio of the length to the diameter is less than 1.4) and the coating design (the coating of multiple precious metal single layers) and the like are adopted to deal with the strategy or configuration that the catalyst is quickly ignited.

The existing engine only carries out debugging on relevant ECU control strategies on the basis of the inherent engine configuration for meeting the requirement of quick light-off of the catalyst, and is a single system consideration in configuration design. Rather than designing and developing the catalyst for rapid light-off as a system or overall concept. Failure to achieve the desired light-off speed for the catalyst makes it difficult to meet more stringent emissions regulations, such as SULEV 20.

As a result of the prior art, a conversion of 50% was achieved at 20 seconds, marginally meeting the SULEV30 target (i.e., 30mg/mile combined nitrogen oxide and hydrocarbon).

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 engine 1000 according to the embodiment of the present invention, the engine 1000 is controlled to include: the fuel injection system 200 is suitable for supplying fuel into a cylinder, and the fuel injection system 200 is a middle direct injection fuel injection system 200.

Wherein the control strategy at least comprises the following steps:

s1: the fuel injection system 200 performs a first fuel injection;

s2: after the engine 1000 completes the 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 (see fig. 9).

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 engine 1000 can be ensured, and the engine 1000 is effectively prevented from catching fire or knocking.

According to the control strategy of the engine 1000 provided by the embodiment of the invention, the fuel supply is carried out by adopting the control strategy of two-time injection, the first fuel injection is completed in the intake stroke, and the second fuel injection is completed in the compression stroke, so that the oil-gas mixture in the cylinder body is more sufficient, the combustion stability is further improved, the working stability of the engine 1000 is improved, and the emission of carbon oxides and nitrogen oxides is reduced.

Further, the determination conditions for the first fuel injection are: injection is performed when engine 1000 is in the intake stroke and the crank angle of engine 1000 is 260 CA-280 CA.

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 engine 1000 when the catalyst 100 is in the ignition working condition, and the fuel and air can be mixed for a longer time.

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 engine 1000 while the catalyst 100 can be ignited quickly.

As shown in fig. 6, the determination conditions for the second fuel injection are: injection is performed after engine 1000 completes the compression stroke and before engine 1000 does not ignite. That is, the second fuel injection has the injection completion timing t1, and the ignition of the engine 1000 has the ignition timing t2, t1 ≦ t 2.

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 engine 1000 more reasonable.

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 engine 1000 at the light-off operation of the catalyst 100 as 1200rpm as an example, the crank angle corresponding to each millisecond is 72 ° CA, and the crank angle corresponding to the pulse width of the second fuel injection of 0.25-0.3 ms is 18 ° CA-21.6 ° CA. Thus, the injection completion timing of the second fuel injection should be advanced by at least 18 ° CA to 21.6 ° CA, in order that the crank angle does not overlap with the ignition timing. While taking into account the crank angle error of about 3 CA, the second fuel injection start timing should be in the range of 21 CA to 24.6 CA. Thus, the fuel-air combustion in engine 1000 is more sufficient after the second fuel injection.

Further, the engine 1000 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.

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 engine 1000 is in the light-off condition of the catalyst 100, so that the spray of the first fuel injection creates turbulence in the cylinder which becomes progressively weaker during the compression stroke, and so that the turbulence is sufficiently attenuated at the crank angle which is correspondingly retarded backwards by-25 CA to-40 CA, so that the first fuel injection can increase the flame spread rate in the combustion chamber.

And further, the cycle fluctuation rate is kept stable, combustion is more stable, and engine 1000 is prevented from misfiring.

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 engine 1000 further comprises a cylinder cover 300, the cylinder cover 300 is a double-channel cylinder cover 300, and an exhaust manifold is integrated on the cylinder cover 300.

Specifically, the cylinder head 300 is integrated with an exhaust manifold, and has a double flow structure (for example, when the engine 1000 is a four-cylinder engine 1000, 1 cylinder and 4 cylinders of the engine 1000 form one flow passage, and 2 cylinder and 3 cylinder form one flow passage).

Thus, on one hand, exhaust interference can be effectively eliminated, residual exhaust gas is reduced from flowing back to the combustion chamber of the engine 1000, and more exhaust gas is discharged into the catalyst 100; on the other hand, the dual flow passages allow the engine 1000 of the present embodiment to have a larger exhaust cam duration (200 ° CA-260 ° CA) so as to exhaust more thoroughly and smoothly without interference among the cylinders, while the exhaust manifold integrated on the cylinder head 300 can reduce the surface area of the exhaust passage so as to reduce heat loss during exhaust gas exhaust, so that more heat energy of the exhaust gas can be transferred to the catalyst 100 during cold start to improve the light-off speed of the catalyst 100.

Further, the engine 1000 further comprises an oxygen sensor 400 and a turbocharger 500 which can realize closed-loop control rapidly, and the closed-loop time of the oxygen sensor 400 is not more than 7 s. Wherein, the shorter the time of the closed-loop control of the oxygen sensor 400, the earlier the engine 1000 can realize the equivalence ratio control, so that the emission value can be effectively reduced.

Further, the turbocharger 500 is provided with the wastegate valve 600, and the maximum opening degree of the wastegate valve 600 is not less than 40 °. In this way, the opening angle of the wastegate valve 600 is made larger, so that more exhaust gas is guided to the catalyst 100 through the wastegate valve 600, and the catalyst 100 can be heated more quickly and sufficiently by the exhaust gas, so that the light-off speed of the catalyst 100 is effectively increased.

It should be noted that the larger the opening degree of the wastegate valve 600, the less the exhaust gas passing through the turbine, and the less heat absorbed by the turbine and the components around the turbine, the more the exhaust gas passes through the wastegate valve 600 into the catalyst 100, so as to increase the temperature rise of the catalyst 100.

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 catalyst 100 while absorbing less heat.

As shown in fig. 3, the axis of the turbine of the turbocharger 500 is at an angle of not less than 120 ° to the axis of the catalyst 100.

The included angle between the axis of the catalyst 100 and the axis of the turbine of the turbocharger 500 has a large influence on the temperature rise of the catalyst 100, and if the included angle between the axis of the catalyst 100 and the axis of the turbine of the turbocharger 500 is too small (for example, acute angle), a large amount of exhaust gas is suddenly in the bent area of the exhaust passage, so that large heat loss is caused, and further, the included angle between the axis of the catalyst 100 and the axis of the turbine of the turbocharger of the embodiment is more reasonable, so that the heat loss of the exhaust gas before entering the catalyst 100 can be further reduced.

As shown in fig. 1 and 2, the catalyst 100 includes: the catalyst carrier 110, the first metal coating 120 and the second metal coating 130, the catalyst carrier 110 having a first region 111 and a second region 112 formed thereon which are connected in sequence; the total amount of the first metal coating 120 is G, the first area 111 is uniformly coated with 0.6G-0.8G of the first metal, and the second area 112 is uniformly coated with 0.2G-0.4G of the first metal; the second metal coating 130 is uniformly coated on the first metal coating 120.

Specifically, the catalyst carrier 110 is coated with two layers of noble metals as a catalyst for catalyzing hydrocarbons and nitrogen oxides in the exhaust gas, and the catalyst carrier 110 is divided into a first region 111 and a second region 112, and then the first region 111 is coated with 0.6-0.8G of the first metal, and correspondingly the second region 112 is coated with 0.2-0.4G of the first metal, and a second metal coating 130 is further coated over the first metal coating 120, so that the density of the first metal on the first region 111 is greater than that on the second region 112.

According to the catalyst 100 of the embodiment of the present invention, the density of the first metal on the first region 111 is greater than the density of the first metal on the second region 112, so that on one hand, the energy required for activating the exhaust gas molecules in the first region 111 is smaller, the exhaust gas molecules can react faster, and the catalyst 100 can be ignited faster; on the other hand, the total amount of hydrocarbons and nitrogen oxides can be further reduced by preferentially performing the combustion reaction of hydrocarbons in the first region 111 and the reduction reaction of nitrogen oxides in the second region 112.

In the particular embodiment shown in fig. 2, the catalyst carrier 110 has a length L, and the first region 111 has a length in the range of: 0.3L-0.4L; the length of the second region 112 ranges from: 0.6L to 0.7L, the first metal of the first metal coating 120 includes: pd; the second metal of the second metal coating 130 includes: pt and Rh.

Specifically, the catalyst 100 of the present embodiment is coated in two divided regions, the second metal coating 130 is a metal coating in which Pt (platinum) and Rh (rhodium) are mixed, the first metal coating 120 is a Pd (palladium) metal coating, and the second metal coating 130 is a divided coating, and the first region 111 (30% to 40% of the total length L of the catalyst carrier 110), the second region 112 (60% to 70% of the total length L of the catalyst carrier 110), and the first region 111, the second region 111, and the second region 112, respectively, are coated with 20% to 40% of the total amount of Pd metal.

Referring to fig. 8, it is shown that when the conversion of hydrocarbon is highest, the coating ratio of Pd metal in the first zone 111 is 60% -80% and the coating ratio of Pd metal in the second zone 112 is 20% -40% (for example, the total coating amount is 10g, the coating ratio of the first zone 111 is 6-8g, and the coating ratio of the second zone 112 is 2-4 g).

Therefore, the length of the first region 111 and the total amount of the Pd metal coating, the length of the second region 112 and the total amount of the Pd metal coating are all in accordance with the use requirements, so that the optimal hydrocarbon conversion rate can be obtained to effectively reduce the content of the hydrocarbon in the exhaust gas.

In the particular embodiment shown in FIG. 1, the length of the catalyst support 110 is L, the width or diameter of the catalyst support 110 is D, and 1.4L/D1.6.

It is understood that, under the premise that the total volume of the catalyst 100 is not changed, the smaller the ratio of the length to the diameter of the catalyst carrier 110 is, the faster the flow rate of the exhaust gas flowing through the catalyst 100 is, and the uniformity of the flow of the exhaust gas is decreased due to the decrease in the diameter of the catalyst 100, the average temperature of the entire catalyst 100 can be significantly increased, and the catalytic performance can be further improved, but the smaller the ratio of the length to the diameter of the catalyst carrier 110 is, the greater the probability of the increase in the back pressure is.

Therefore, in order to balance the catalytic performance and the backpressure, the catalyst 100 of the embodiment limits the ratio of the length to the diameter of the catalyst carrier 110 in the above range, so that the catalytic efficiency and the catalytic effect of the catalyst 100 are improved, and meanwhile, the probability of backpressure increase of the catalyst 100 is reduced, so that the catalyst 100 has higher working stability and longer service life.

According to the control strategy of the engine 1000 of the embodiment of the invention, the fuel supply is carried out by adopting the control strategy of two-time injection, and further the structures of the fuel injection system 200 and the cylinder head 300, the catalyst 100, the oxygen sensor 400, the supercharger and the waste gate valve 600 are all suitable for the engine 1000 of the two-time injection strategy, so that the injection effect, the fuel injection quantity and the ignition time of the engine 1000 of the first time fuel injection and the second time fuel injection are more reasonable, the working stability of the engine 1000 can be further improved, and the emission of carbon oxides and nitrogen oxides can be reduced.

In summary, the engine 1000 of the present embodiment, which adopts the control strategy of the engine 1000, has the following advantages:

(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 1000 do not need to be improved in the control strategy direction, the problems of large noise, large vibration and the like of the engine 1000 do not occur, and the use experience of customers can be effectively improved;

(2) the spark advance can be retarded by a large angle, resulting in higher exhaust temperatures so that catalyst 100 can light off quickly;

(3) the arrangement of the middle direct injection type fuel injection system 200 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 1000 is cold started, the heat dissipation of the exhaust passage and the cylinder head 300 is small, and the residual exhaust gas backflow is reduced, so that the catalyst 100 can be heated by the exhaust gas more quickly;

(5) the oxygen sensor 400 has a short closed-loop time, and the emissions of hydrocarbons and nitrogen oxides generated before the oxygen sensor 400 is closed-loop are high, i.e., the emission limit is exceeded before the catalyst 100 is ignited;

(6) the maximum opening angle of the waste gate valve 600 is large, and more waste gas can be discharged to the catalyst 100 through the waste gate valve 600 in the starting stage, so that more waste gas with higher temperature can participate in the heating process of the catalyst 100, the catalyst 100 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 100 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 coating of the catalytic converter 100 is designed to be a precious metal double-layer coating, and the precious metal coating is designed in a targeted manner according to the internal reaction of the catalytic converter 100, so that the conversion efficiency is lower; meanwhile, the ratio of the specification length to the diameter of the catalyst 100 is reasonable, so that the gas flowing into the catalyst 100 is more uniform, and the catalytic performance is higher;

As shown in fig. 1 and 2, in the engine 1000 employing the present embodiment, the control strategy of the present embodiment and the embodiment of the catalyst 100 are applied.

First, in terms of control strategy: the ignition time, the oil injection time and the oil injection frequency of the engine 1000 are reasonably controlled, meanwhile, in the aspect of hardware of the engine 1000, a fuel injection system 200 with middle direct injection is selected, a double-channel cylinder cover 300 is adopted, an exhaust manifold is integrated on the cylinder cover 300, an oxygen sensor 400 capable of realizing quick closed loop, a waste gas bypass valve 600 with the opening degree not less than 40 degrees and a low-heat capacity supercharger are selected, and the angle between a catalyst 100 and a turbine is reasonably set.

Finally, the control strategy and the hardware configuration form a catalyst 100 rapid light-off system, and the rapid light-off of the catalyst 100 is realized.

Thus, referring to FIG. 1, the light-off temperature of catalyst 100 may reach 350 degrees Celsius at 13.3 seconds after engine 1000 is started, and the conversion efficiency of catalyst 100 may reach 80 percent, as shown in FIG. 2, where neither hydrocarbon nor NOx emissions exceed 20mg/mile before 21.8 seconds.

That is, in the test standard of SULEV20, 20 seconds before the FTP cycle is idle, and the engine 1000 of the present embodiment meets the standard for hydrocarbon and nox emissions throughout the idle, meeting the requirements of SULEV20 emissions regulations.

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.

Claims

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.