Engine single-cylinder EGR control system and method
阅读说明：本技术 一种发动机单缸egr控制系统及方法 (Engine single-cylinder EGR control system and method ) 是由 王颖 李铁东 张松 鲍经纬 李启鹏 于 2020-10-20 设计创作，主要内容包括：本发明公开了一种发动机单缸EGR控制系统,包括：EGR装置,其包含有EGR非专用缸、EGR专用缸以及涡轮机,涡轮机的输出端与EGR专用缸的输出端之间设置有冷启动阀,EGR专用缸的输出端与EGR非专用缸以及EGR专用缸的输入端之间设置有EGR阀；空气流量传感器采集EGR装置的进气流量数据；第一氧传感器采集涡轮机排出气体中的氧浓度数据；第二氧传感器采集EGR专用缸排出气体中的氧浓度数据；第一压力传感器采集混合器排出的气体压力数据；第一温度传感器采集混合器排出的气体温度数据；电子控制单元计算EGR率,调节冷启动阀以及EGR阀的阀门开度,对EGR率进行修正,对发动机进行点火控制。本发明能够对单缸EGR装置瞬态工况实现精确控制。(The invention discloses an engine single-cylinder EGR control system, which comprises: the EGR device comprises an EGR non-special cylinder, an EGR special cylinder and a turbine, wherein a cold starting valve is arranged between the output end of the turbine and the output end of the EGR special cylinder, and an EGR valve is arranged between the output end of the EGR special cylinder and the input ends of the EGR non-special cylinder and the EGR special cylinder; the air flow sensor acquires air intake flow data of the EGR device; a first oxygen sensor acquiring oxygen concentration data in turbine exhaust gas; acquiring oxygen concentration data in exhaust gas of the EGR special cylinder by a second oxygen sensor; the method comprises the steps that a first pressure sensor collects gas pressure data discharged by a mixer; the first temperature sensor acquires temperature data of gas discharged by the mixer; the electronic control unit calculates the EGR rate, adjusts the valve openings of the cold start valve and the EGR valve, corrects the EGR rate, and performs ignition control on the engine. The invention can realize accurate control on the transient working condition of the single-cylinder EGR device.)
1. An engine single cylinder EGR control system, comprising:
an EGR device, the EGR device comprising: an EGR non-dedicated cylinder, an EGR dedicated cylinder, a turbine, a mixer, an output end of the mixer connected with input ends of the EGR non-dedicated cylinder and the EGR dedicated cylinder, an input end of the mixer connected with an output end of the EGR dedicated cylinder and an input end of the mixer also receiving air outside the vehicle, an input end of the turbine connected with an output end of the EGR non-dedicated cylinder, an output end of the turbine connected with an output end of the EGR dedicated cylinder, and an output end of the EGR dedicated cylinder also connected with input ends of the EGR non-dedicated cylinder and the EGR dedicated cylinder, a cold start valve being provided between the output end of the turbine and the output end of the EGR dedicated cylinder, and an EGR valve being provided between the output end of the EGR dedicated cylinder and the input ends of the EGR non-dedicated cylinder and the EGR dedicated cylinder;
an air flow sensor for acquiring intake air flow data of the EGR device;
a first oxygen sensor for collecting oxygen concentration data in the turbine exhaust gas;
the second oxygen sensor is used for acquiring oxygen concentration data in the exhaust gas of the EGR special cylinder;
a first pressure sensor for collecting gas pressure data from the mixer;
the first temperature sensor is used for acquiring temperature data of the gas discharged by the mixer;
and the electronic control unit is connected with the air flow sensor, the first oxygen sensor, the second oxygen sensor, the first pressure sensor and the first temperature sensor, and is used for calculating an EGR rate according to the intake air flow data and the oxygen concentration data in the exhaust gas of the EGR special cylinder, adjusting the valve opening degrees of the cold start valve and the EGR valve according to the gas pressure data discharged by the mixer and the gas temperature data discharged by the mixer, correcting the EGR rate to confirm the position of the EGR gas, and performing ignition control on the engine according to the position of the EGR gas.
2. The engine single cylinder EGR control system of claim 1 wherein said EGR apparatus further comprises: the system comprises an air filter, a gas compressor, a catalyst, an air inlet intercooler, an air inlet manifold and an EGR cooler;
the air filter is connected with the air compressor through a pipeline, and the air compressor, the mixer, the air intake intercooler and the air intake manifold are sequentially connected through a pipeline;
the intake manifold is connected to the EGR non-dedicated cylinder and the EGR dedicated cylinder, respectively;
the turbine is connected with the EGR non-dedicated cylinder and the catalyst respectively through different pipelines;
the special EGR cylinder is connected with the catalyst through a pipeline, and the cold starting valve is arranged on the pipeline between the special EGR cylinder and the catalyst;
the EGR cooler is respectively connected with the intake manifold and the mixer through pipelines, and the pipeline between the EGR cooler and the mixer is provided with the EGR valve.
3. The engine single cylinder EGR control system of claim 2 wherein the first oxygen sensor is disposed on a conduit between the catalyst and the turbine, the second oxygen sensor is disposed on a conduit between the EGR cooler and the mixer, and the first pressure sensor and the first temperature sensor are disposed on a conduit between the mixer and the intake charge air cooler.
4. The engine single cylinder EGR control system of claim 2, further comprising:
a second temperature sensor disposed on a conduit between the EGR cooler and the mixer for collecting gas temperature data in the EGR cooler exhaust gas:
a second pressure sensor disposed in the intake manifold for collecting gas pressure data at the intake manifold inlet;
and the electronic control unit is also in communication connection with the second temperature sensor and the second pressure sensor respectively and is used for judging whether the EGR device is in a set normal working state or not according to the gas temperature data in the exhaust gas of the EGR cooler and the gas pressure data at the inlet of the intake manifold.
5. The engine single cylinder EGR control system according to claim 1, wherein the electronic control unit is further configured to, when it is determined that the vehicle is in a rapid acceleration condition, control a throttle valve of the vehicle to open, and when the mixer exhaust gas pressure data decreases and the intake air flow data increases after the throttle valve opens, control the EGR valve to open, and control a supercharger control valve of the turbine to open, and determine an ignition angle and an injection timing of the engine, and injection amounts of the EGR non-dedicated cylinder and the EGR dedicated cylinder, based on the oxygen concentration data in the turbine exhaust gas, the oxygen concentration data in the EGR dedicated cylinder exhaust gas, the mixer exhaust gas pressure data, and the mixer exhaust gas temperature data.
6. The engine single cylinder EGR control system of claim 1, wherein the electronic control unit is further configured to control a throttle valve of the vehicle to close when it is determined that the vehicle is in a rapid deceleration condition, and after the throttle valve is closed, when the gas pressure data discharged from the mixer increases and the intake air flow data decreases, to control a valve opening of the EGR valve to decrease at a set rate and to control the cold start valve to open and to control a supercharger bypass of the turbine to open, and further based on the intake air flow data, the oxygen concentration data in the turbine exhaust gas, the oxygen concentration data in the exhaust gas from the EGR-dedicated cylinder, the gas pressure data discharged from the mixer, the gas temperature data discharged from the mixer, and the valve opening signal of the cold start valve and the valve opening signal of the EGR valve, adjusting valve openings of the EGR valve and the cold start valve.
7. The engine single cylinder EGR control system of claim 1,
the air flow sensor is also used for collecting the air inlet temperature data of the EGR device;
the electronic control unit is further configured to control the EGR valve, the cold start valve, and a throttle valve of the vehicle to open when the vehicle is determined to be in a low-temperature cold start condition according to an engine start signal of the vehicle and the intake air temperature data, and correct the valve opening of the EGR valve according to the gas pressure data discharged from the mixer, the gas temperature data discharged from the mixer, the valve opening data of the EGR valve, and the oxygen concentration data in the exhaust gas of the EGR-dedicated cylinder to reduce the cold start time of the EGR apparatus, and correct the valve opening of the cold start valve according to the oxygen concentration data in the exhaust gas of the turbine.
8. An engine single cylinder EGR control method, characterized in that the method is applied to the control system of any one of claims 1-7, and the method comprises:
collecting intake air flow data of the EGR device through an air flow sensor;
collecting oxygen concentration data in the turbine exhaust gas via a first oxygen sensor;
acquiring oxygen concentration data in the exhaust gas of the EGR special cylinder through a second oxygen sensor;
collecting gas pressure data discharged by the mixer through a first pressure sensor;
acquiring temperature data of the gas discharged by the mixer through a first temperature sensor;
and calculating an EGR rate through an electronic control unit according to the air inlet flow data and the oxygen concentration data in the exhaust gas of the EGR special cylinder, adjusting the valve opening degree of a cold start valve and the valve opening degree of the EGR valve according to the gas pressure data discharged from the mixer and the temperature data discharged from the mixer, correcting the EGR rate to confirm the position of the EGR gas, and then carrying out ignition control on the engine according to the position of the EGR gas.
9. The engine single cylinder EGR control method of claim 8, further comprising:
and when the electronic control unit judges that the vehicle is in a rapid acceleration working condition, controlling a throttle valve of the vehicle to be opened, reducing gas pressure data discharged by the mixer after the throttle valve is opened, and controlling the EGR valve to be opened when the intake air flow data is increased, controlling a supercharger control valve of the turbine to be opened, and determining an ignition angle and an oil injection time of the engine and oil injection quantities of the EGR non-dedicated cylinder and the EGR dedicated cylinder according to oxygen concentration data in exhaust gas of the turbine, oxygen concentration data in exhaust gas of the EGR dedicated cylinder, gas pressure data discharged by the mixer and temperature data of exhaust gas of the mixer.
10. The engine single cylinder EGR control method of claim 8, further comprising:
when the electronic control unit judges that the vehicle is in a rapid deceleration working condition, the electronic control unit controls a throttle valve of the vehicle to be closed, after the throttle valve is closed, when the gas pressure data exhausted by the mixer is increased and the gas flow data is reduced, the electronic control unit controls the valve opening degree of the EGR valve to be reduced according to a set rate, controls the cold start valve to be opened and controls a supercharger bypass channel of the turbine to be opened, and further regulates the valve opening degrees of the EGR valve and the cold start valve according to the gas flow data, the oxygen concentration data in the gas exhausted by the turbine, the oxygen concentration data in the gas exhausted by the EGR special cylinder, the gas pressure data exhausted by the mixer, the gas temperature data exhausted by the mixer, the valve opening degree signal of the cold start valve and the valve opening degree signal of the EGR valve.
Technical Field
The invention relates to the technical field of automobile engines, in particular to a single-cylinder EGR control system and a single-cylinder EGR control method for an engine.
Background
The development of gasoline engines with high efficiency and low fuel consumption is an important subject facing the automobile industry. The main factors restricting the low-load thermal efficiency improvement of the gasoline engine comprise high pumping loss, low geometric compression ratio, low specific heat ratio of mixed gas and the like. While for high loads, detonation combustion is the main obstacle leading to low thermal efficiency of gasoline engines. One of the technological routes for improving the low load and high load thermal efficiency of gasoline engine is to cool the exhaust gas from the engine and to re-enter the cylinder for combustion, i.e. exhaust gas recirculation technology.
In a single cylinder EGR (Exhaust Gas recirculation) system of a vehicle, the EGR device comprises an air inlet manifold, a mixer, a plurality of non-special cylinders for EGR and a special cylinder for EGR, wherein Gas exhausted by the special cylinders for EGR or the non-special cylinders for EGR and fresh air entering from the outside form EGR Gas, the EGR Gas is mixed in the mixer and then is sent into the non-special cylinders for EGR and the special cylinders for EGR to burn, under the acceleration working condition of the vehicle, the EGR Gas does not enter the air inlet manifold, and when a transmitter ignites according to the basic ignition angle of the non-special cylinders for EGR, knocking can be generated.
When the vehicle is in a complete vehicle rapid deceleration working condition, if the EGR device is still in the passage, the EGR device can still introduce the over-concentrated EGR gas into the EGR non-special cylinder, and the EGR non-special cylinder is ignited.
When the vehicle is in a cold start condition at a low temperature, or when the vehicle is just started, if the EGR apparatus enters an EGR rate of 25%, it causes: a. the supercharger of the turbine does not work, and the power of the engine is obviously reduced; b. excessive EGR gas enters the EGR non-dedicated cylinder and the EGR dedicated cylinder, which is not favorable for combustion, and causes a problem of difficulty in light-off.
In the engine outer characteristic region, an EGR rate of 25% is entered, and at this time, the EGR after-temperature is high, which causes the temperature of the gas in the intake manifold to be excessively high, resulting in knocking of the normal cylinder.
Aiming at the development of a single-cylinder EGR device, the transient change can directly generate the rapid change of the EGR rate and combustion, and the accuracy requirement of transient control is higher than that of the traditional EGR technology. Meanwhile, the combustion control of the EGR non-special cylinder and the combustion control of the EGR special cylinder are different, the generated products are different, and the requirement on the combustion accuracy is higher in transient change.
Therefore, a solution is needed that can accurately control the transient operating conditions of a single cylinder EGR device.
Disclosure of Invention
The embodiment of the application provides the single-cylinder EGR control method for the engine, so that the transient working condition of the single-cylinder EGR device can be accurately controlled.
The invention provides an engine single cylinder EGR control system, which comprises:
an EGR device, the EGR device comprising: an EGR non-dedicated cylinder, an EGR dedicated cylinder, a turbine, a mixer, an output end of the mixer connected with input ends of the EGR non-dedicated cylinder and the EGR dedicated cylinder, an input end of the mixer connected with an output end of the EGR dedicated cylinder and an input end of the mixer also receiving air outside the vehicle, an input end of the turbine connected with an output end of the EGR non-dedicated cylinder, an output end of the turbine connected with an output end of the EGR dedicated cylinder, and an output end of the EGR dedicated cylinder also connected with input ends of the EGR non-dedicated cylinder and the EGR dedicated cylinder, a cold start valve being provided between the output end of the turbine and the output end of the EGR dedicated cylinder, and an EGR valve being provided between the output end of the EGR dedicated cylinder and the input ends of the EGR non-dedicated cylinder and the EGR dedicated cylinder;
an air flow sensor for acquiring intake air flow data of the EGR device;
a first oxygen sensor for collecting oxygen concentration data in the turbine exhaust gas;
the second oxygen sensor is used for acquiring oxygen concentration data in the exhaust gas of the EGR special cylinder;
a first pressure sensor for collecting gas pressure data from the mixer;
the first temperature sensor is used for acquiring temperature data of the gas discharged by the mixer;
and the electronic control unit is connected with the air flow sensor, the first oxygen sensor, the second oxygen sensor, the first pressure sensor and the first temperature sensor, and is used for calculating an EGR rate according to the intake air flow data and the oxygen concentration data in the exhaust gas of the EGR special cylinder, adjusting the valve opening degrees of the cold start valve and the EGR valve according to the gas pressure data discharged by the mixer and the gas temperature data discharged by the mixer, correcting the EGR rate to confirm the position of the EGR gas, and performing ignition control on the engine according to the position of the EGR gas.
Preferably, the EGR apparatus further includes: the system comprises an air filter, a gas compressor, a catalyst, an air inlet intercooler, an air inlet manifold and an EGR cooler;
the air filter is connected with the air compressor through a pipeline, and the air compressor, the mixer, the air intake intercooler and the air intake manifold are sequentially connected through a pipeline;
the intake manifold is connected to the EGR non-dedicated cylinder and the EGR dedicated cylinder, respectively;
the turbine is connected with the EGR non-dedicated cylinder and the catalyst respectively through different pipelines;
the special EGR cylinder is connected with the catalyst through a pipeline, and the cold starting valve is arranged on the pipeline between the special EGR cylinder and the catalyst;
the EGR cooler is respectively connected with the intake manifold and the mixer through pipelines, and the pipeline between the EGR cooler and the mixer is provided with the EGR valve.
Preferably, the first oxygen sensor is provided on a pipe between the catalyst and the turbine, the second oxygen sensor is provided on a pipe between the EGR cooler and the mixer, and the first pressure sensor and the first temperature sensor are provided on a pipe between the mixer and the intake charge air cooler.
Preferably, the method further comprises the following steps:
a second temperature sensor disposed on a conduit between the EGR cooler and the mixer for collecting gas temperature data in the EGR cooler exhaust gas:
a second pressure sensor disposed in the intake manifold for collecting gas pressure data at the intake manifold inlet;
and the electronic control unit is also in communication connection with the second temperature sensor and the second pressure sensor respectively and is used for judging whether the EGR device is in a set normal working state or not according to the gas temperature data in the exhaust gas of the EGR cooler and the gas pressure data at the inlet of the intake manifold.
Preferably, the electronic control unit is further configured to, when it is determined that the vehicle is in a rapid acceleration condition, control a throttle valve of the vehicle to open, and when the gas pressure data discharged from the mixer decreases after the throttle valve opens and the intake air flow data increases, control the EGR valve to open, and control a supercharger control valve of the turbine to open, and determine an ignition angle and an injection timing of the engine, and injection amounts of the EGR non-dedicated cylinder and the EGR dedicated cylinder, based on the oxygen concentration data in the turbine exhaust gas, the oxygen concentration data in the EGR dedicated cylinder exhaust gas, the gas pressure data discharged from the mixer, and the temperature data discharged from the mixer.
Preferably, the electronic control unit is further configured to control a throttle valve of the vehicle to close when the vehicle is determined to be in a rapid deceleration condition, and after the throttle valve is closed, controlling a valve opening degree of the EGR valve to decrease at a set rate when the gas pressure data discharged from the mixer increases and the intake air flow data decreases, and controls the cold start valve to open, controls a supercharger bypass passage of the turbine to open, and further controls the cold start valve to open, according to the intake air flow data, the oxygen concentration data in the turbine exhaust gas, the oxygen concentration data in the EGR-dedicated cylinder exhaust gas, the gas pressure data from the mixer, and the gas temperature data from the mixer, and the valve opening signal of the cold start valve and the valve opening signal of the EGR valve, and adjusting the valve openings of the EGR valve and the cold start valve.
Preferably, the air flow sensor is further used for collecting the intake air temperature data of the EGR device;
the electronic control unit is further configured to control the EGR valve, the cold start valve, and a throttle valve of the vehicle to open when the vehicle is determined to be in a low-temperature cold start condition according to an engine start signal of the vehicle and the intake air temperature data, and correct the valve opening of the EGR valve according to the gas pressure data discharged from the mixer, the gas temperature data discharged from the mixer, the valve opening data of the EGR valve, and the oxygen concentration data in the exhaust gas of the EGR-dedicated cylinder to reduce the cold start time of the EGR apparatus, and correct the valve opening of the cold start valve according to the oxygen concentration data in the exhaust gas of the turbine.
The invention also provides a single-cylinder EGR control method of the engine, which is applied to the control system and comprises the following steps:
collecting intake air flow data of the EGR device through an air flow sensor;
collecting oxygen concentration data in the turbine exhaust gas via a first oxygen sensor;
acquiring oxygen concentration data in the exhaust gas of the EGR special cylinder through a second oxygen sensor;
collecting gas pressure data discharged by the mixer through a first pressure sensor;
acquiring temperature data of the gas discharged by the mixer through a first temperature sensor;
and calculating an EGR rate through an electronic control unit according to the air inlet flow data and the oxygen concentration data in the exhaust gas of the EGR special cylinder, adjusting the valve opening degree of a cold start valve and the valve opening degree of the EGR valve according to the gas pressure data discharged from the mixer and the temperature data discharged from the mixer, correcting the EGR rate to confirm the position of the EGR gas, and then carrying out ignition control on the engine according to the position of the EGR gas.
Preferably, the method further comprises the following steps:
and when the electronic control unit judges that the vehicle is in a rapid acceleration working condition, controlling a throttle valve of the vehicle to be opened, reducing gas pressure data discharged by the mixer after the throttle valve is opened, and controlling the EGR valve to be opened when the intake air flow data is increased, controlling a supercharger control valve of the turbine to be opened, and determining an ignition angle and an oil injection time of the engine and oil injection quantities of the EGR non-dedicated cylinder and the EGR dedicated cylinder according to oxygen concentration data in exhaust gas of the turbine, oxygen concentration data in exhaust gas of the EGR dedicated cylinder, gas pressure data discharged by the mixer and temperature data of exhaust gas of the mixer.
Preferably, the method further comprises the following steps:
when the electronic control unit judges that the vehicle is in a rapid deceleration working condition, the electronic control unit controls a throttle valve of the vehicle to be closed, after the throttle valve is closed, when the gas pressure data exhausted by the mixer is increased and the gas flow data is reduced, the electronic control unit controls the valve opening degree of the EGR valve to be reduced according to a set rate, controls the cold start valve to be opened and controls a supercharger bypass channel of the turbine to be opened, and further regulates the valve opening degrees of the EGR valve and the cold start valve according to the gas flow data, the oxygen concentration data in the gas exhausted by the turbine, the oxygen concentration data in the gas exhausted by the EGR special cylinder, the gas pressure data exhausted by the mixer, the gas temperature data exhausted by the mixer, the valve opening degree signal of the cold start valve and the valve opening degree signal of the EGR valve.
The implementation of the invention has the following beneficial effects: when a vehicle is under working conditions of rapid acceleration, rapid deceleration, low-temperature cold start of an engine and the like, air inlet flow data of an EGR device can be collected through an air flow sensor, oxygen concentration data in exhaust gas of a turbine is collected through a first oxygen sensor, oxygen concentration data in exhaust gas of an EGR special cylinder is collected through a second oxygen sensor, gas pressure data discharged from a mixer is collected through a first pressure sensor, temperature data discharged from the mixer is collected through a first temperature sensor, after the data are collected through the sensors, the EGR rate is calculated through an electronic control unit according to the air inlet flow data and the oxygen concentration data in the exhaust gas of the EGR special cylinder, the valve opening degrees of a cold start valve and the EGR valve are adjusted according to the gas pressure data discharged from the mixer and the gas temperature data discharged from the mixer, and the EGR rate is corrected, the method has the advantages that the position of EGR gas is confirmed, the ignition angle and the oil injection time of the engine are determined according to the position of the EGR gas, the situation that the engine is ignited in advance to cause knocking of the EGR non-special cylinder is avoided, the situation that fire occurs in the EGR non-special cylinder due to the fact that the over-concentrated EGR gas is guided into the EGR non-special cylinder under the condition of rapid deceleration is avoided, the problem of engine power reduction caused by the fact that the EGR rate is too high can be avoided, and accurate control over transient working conditions of a single-cylinder EGR device is achieved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
FIG. 1 is a schematic diagram of an engine single cylinder EGR control system provided by the present invention;
FIG. 2 is a flowchart illustrating a single cylinder EGR control method for an engine according to the present invention during a vehicle rapid acceleration condition;
FIG. 3 is a flowchart illustrating a single cylinder EGR control method for an engine according to the present invention during a vehicle deceleration condition;
FIG. 4 is a flowchart illustrating the operation of the single cylinder EGR control method of the present invention during low temperature cold start operation of the vehicle.
Detailed Description
In order to make the present application more clearly understood by those skilled in the art to which the present application pertains, the following detailed description of the present application is made with reference to the accompanying drawings by way of specific embodiments.
The invention provides an engine single cylinder EGR (Exhaust Gas recirculation) control system, as shown in figure 1, the system comprises: an EGR device, an air flow sensor 1, a first oxygen sensor 2, a second oxygen sensor 3, a first pressure sensor 5, a first temperature sensor 6, and an electronic control unit (not shown in the figure). The air flow sensor 1, the first oxygen sensor 2, the second oxygen sensor 3, the first pressure sensor 5, and the first temperature sensor 6 are all provided in the EGR device.
The EGR device comprises EGR non-dedicated cylinders (also called EGR non-dedicated cylinders) 8, 9 and 10, an EGR dedicated cylinder (also called EGR dedicated cylinder) 11, a turbine 14 and a mixer 17, wherein the output end of the mixer 17 is connected with the input ends of the EGR non-dedicated cylinders 8, 9 and 10 and the EGR dedicated cylinder 11, the input end of the mixer 17 is connected with the output end of the EGR dedicated cylinder 11, the input end of the mixer 17 also receives fresh air outside the vehicle, the input end of the turbine 14 is connected with the output ends of the EGR non-dedicated cylinders 8, 9 and 10 through pipelines, the output end of the turbine 14 is connected with the output end of the EGR dedicated cylinder 11 through a pipeline, the output end of the EGR dedicated cylinder 11 is further connected with the input ends of the EGR non-dedicated cylinders 8, 9 and 10 and the EGR dedicated cylinder 11 through pipelines, a cold start valve 21 is arranged between the output end of the turbine 14 and the output end of the EGR dedicated cylinder 11, and the output end of the EGR dedicated cylinder 11 is, 9. An EGR valve 20 is provided between the input ends of the EGR cylinder 11 and the EGR cylinder 10. The gas discharged from the EGR non-dedicated cylinders 8, 9, and 10 may not be reused, and the gas discharged from the EGR dedicated cylinder 11 needs to be reused.
The air flow sensor 1 is used to collect intake air flow data of the EGR device. The air flow sensor 1 may integrate a temperature acquisition function.
The first oxygen sensor 2 is used to collect oxygen concentration data in the exhaust gas of the turbine 14.
The second oxygen sensor 3 (i.e., a line oxygen sensor) is used to collect oxygen concentration data in the exhaust gas of the EGR-dedicated cylinder 11.
The first pressure sensor 5 is used to collect gas pressure data after the mixer 17.
The first temperature sensor 6 is used for collecting gas temperature data after the mixer 17.
The electronic control unit is respectively connected with the air flow sensor 1, the first oxygen sensor 2, the second oxygen sensor 3, the first pressure sensor 5 and the first temperature sensor 6, and is used for calculating an EGR rate (which is the ratio of the amount of recirculated exhaust gas to the total amount of intake air sucked into the cylinder and can also be called EGR flow) according to intake air flow data and oxygen concentration data in exhaust gas of the special EGR cylinder 11, adjusting the valve opening degree of the cold start valve 21 and the valve opening degree of the EGR valve 20 according to gas pressure data after the mixer 17 and gas temperature data after the mixer 17, correcting the EGR rate to confirm the position of the EGR gas, and performing ignition control on the engine according to the position of the EGR gas (for example, the ignition angle and the fuel injection time of the engine can be adjusted) to realize accurate control of the transient working condition of the single-cylinder EGR device.
Specifically, in the test process of the EGR device, data of the sensors under various working conditions are collected to form a corresponding table model, then according to the current working condition of the vehicle, the table model is queried, theoretical sampling values of the first pressure sensor 5 and the first temperature sensor 6 can be obtained, whether actual sampling values of the first pressure sensor 5 and the first temperature sensor 6 are consistent with the theoretical values or not is judged, if yes, after EGR gas (including fresh air entering the EGR device and gas exhausted from the EGR dedicated cylinder 11) reaches the mixer 17 is judged, the position of the EGR gas can be determined, the time when the EGR gas enters the EGR dedicated cylinder 11 from the mixer 17 can be determined through tests, and the ignition angle and the oil injection time of the engine can be determined.
The time for the EGR gas to enter the mixer 17 is relatively long (e.g., 5 seconds), dynamic, and not accurately obtained, but after the EGR gas passes through the mixer 17, the time to the EGR non-dedicated cylinders 8, 9, 10 and the EGR-dedicated cylinder 11 is relatively short (e.g., 0.5 seconds), which is relatively fixed, and can be obtained through experiments, and after it is judged that the EGR gas passes through the mixer 17 through the data collected by the first pressure sensor 5 and the first temperature sensor 6, the time for the EGR gas to enter the EGR non-dedicated cylinders and the EGR-dedicated cylinders can be determined, thereby determining the ignition angle and the fuel injection timing of the engine.
The invention can solve the problems that in the working condition process of vehicle rapid acceleration and rapid deceleration, under the conditions of low-temperature cold start, low load and high load of the engine, a corresponding control strategy is formulated through data acquisition of related sensors, so that the linkage control of the cold start valve 21 and the EGR valve 20 in the system is coordinated, the dynamic property and stable combustion control of the engine are met, and the accurate oil injection time and the oil injection quantity are formulated.
The cold start valve 21 of the control system in the embodiment of the present invention is normally closed, and is opened only when it is necessary to cooperate and link with the EGR valve 20 (Exhaust Gas recirculation valve). Cold start valve 21 is used for when vehicle rapid deceleration operating mode and vehicle low temperature cold start operating mode, to the operating mode that does not need 25% EGR rate, with the linkage of EGR valve 20, reduces the EGR rate, realizes the control of combustion stability and responsiveness to and at low temperature cold start operating mode, be used for promoting the quick ignition requirement of catalyst.
The EGR valve 20 of the control system in the embodiment of the invention is in a normally open state, and under the working conditions of constant-speed running of a vehicle and the like, a special EGR cylinder is required to provide a stable 25% EGR rate.
The combustion control of a single EGR dedicated cylinder (or referred to as an EGR dedicated cylinder) is different from the other three ordinary EGR non-dedicated cylinders 8, 9, and 10, the EGR dedicated cylinder 11 is mainly used for generating an exhaust gas environment where lamder (i.e., air-to-oxygen ratio) is 0.7-0.8, and after the gas exhausted from the EGR dedicated cylinder 11 is collected into the ordinary EGR non-dedicated cylinders 8, 9, and 10 by circulation, lamder on an exhaust passage after combustion needs to be equal to 1, so that the combustion control needs to be implemented by monitoring the exhaust gas on the EGR passage and adjusting the combustion control immediately.
The EGR apparatus further includes: an air filter 12, a compressor 13, a catalyst 15, a mixer 17, an intake charge air cooler 18, an intake manifold 19, and an EGR cooler 16.
The air filter 12 is connected to the compressor 13 through a pipe, and the compressor 13, the mixer 17, the intake intercooler 18, and the intake manifold 19 are connected in sequence through pipes.
The intake manifold 19 is connected to the EGR non-dedicated cylinders 8, 9, and 10 and the EGR dedicated cylinder 11, respectively;
the turbine 14 is connected to the EGR non-dedicated cylinders 8, 9, 10 and the catalyst 15 through different pipes, respectively;
the EGR special cylinder 11 is connected with the catalyst 15 through a pipeline, and a cold start valve 21 is arranged on the pipeline between the EGR special cylinder 11 and the catalyst 15;
the EGR cooler 16 is connected to an intake manifold 19 and a mixer 17 by pipes, respectively, and an EGR valve 20 is provided in the pipe between the EGR cooler 16 and the mixer 17.
The first oxygen sensor 2 is arranged on a pipe between the catalyst 15 and the turbine 14, the second oxygen sensor 3 is arranged on a pipe between the EGR cooler 16 and the mixer 17, and the first pressure sensor 5 and the first temperature sensor 6 are arranged on a pipe between the mixer 17 and the intake charge air cooler 18.
Exhaust gas generated by the EGR non-dedicated cylinders 8, 9, and 10 is treated by the catalyst 15 and discharged.
The single-cylinder EGR control system of the engine further comprises: a second temperature sensor 4 and a second pressure sensor 7.
The second temperature sensor 4 is arranged in the line between the EGR cooler 16 and the mixer 17 for acquiring gas temperature data in the exhaust gases of the EGR cooler 16.
A second pressure sensor 7 is provided in the intake manifold 19 for collecting gas pressure data at the inlet of the intake manifold 19.
The electronic control unit is also in communication connection with the second temperature sensor 4 and the second pressure sensor 7, respectively, and is configured to determine whether the EGR apparatus is in a set normal operating state according to gas temperature data in the exhaust gas of the EGR cooler 16 and gas pressure data at an inlet of the intake manifold 19.
As shown in fig. 2, the electronic control unit (i.e., ECU) is also configured to control the throttle valve of the vehicle to open when it is determined that the vehicle is in a rapid acceleration condition, and to control the EGR valve 20 to open and the supercharger control valve of the turbine 14 to open when the gas pressure data after the mixer 17 decreases and the intake air flow data increases after the throttle valve opens, and to determine the ignition angle and the fuel injection timing of the engine and the fuel injection amounts of the EGR non-dedicated cylinders 8, 9, 10 and the EGR-dedicated cylinder 11 based on the oxygen concentration data in the exhaust gas of the turbine 14, the oxygen concentration data in the exhaust gas of the EGR-dedicated cylinder 11, the gas pressure data after the mixer 17, and the gas temperature data after the mixer 17. In this preferred embodiment, the electronic control unit judges the vehicle acceleration value through the accelerator pedal signal, and when the vehicle acceleration value is greater than the first set acceleration value, the rapid acceleration condition can be judged. It is understood that the electronic control unit may also acquire the acceleration value of the vehicle through an acceleration sensor and a radar device arranged on the vehicle.
In the process of vehicle rapid acceleration, after an electronic control unit of an engine receives a signal of an accelerator pedal, a throttle valve is opened, after the throttle valve is opened, the pressure behind a mixer 17 is reduced, and simultaneously the flow of intake air is increased, the signal feedback of a pressure sensor and a temperature sensor behind the mixer 17 is combined with a pressure model (the pressure model can be obtained by induction according to engine test data) in front of the mixer 17, which is established in the electronic control unit, the duty ratio data required to be input to an EGR valve 20 can be calculated through table lookup, and the EGR valve 20 is opened; meanwhile, the electronic control unit inputs duty ratio data to the electric control actuator of the supercharger, the supercharger controller is opened in a test, the supercharging pressure of the engine is increased, and the dynamic property is improved. After the operation is finished, an electric control actuator of the supercharger can feed back position signals to the electronic control unit, an exhaust oxygen sensor can feed back lamder signals in exhaust, the electronic control unit on the EGR passage mainly judges the combustion state of the engine according to pressure, temperature signals and linear oxygen signals after the mixer 17 so as to quickly delay an ignition angle, and the oil injection amount and the oil injection time of normal cylinders (namely EGR non-special cylinders 8, 9 and 10) and special cylinders (EGR special cylinder 11) are adjusted in real time according to the feedback signals, so that the quick acceleration responsiveness is realized.
As shown in fig. 3, the electronic control unit is further configured to control the throttle valve of the vehicle to close when the vehicle is determined to be in the rapid deceleration condition, control the valve opening of the EGR valve 20 to decrease at a set rate and control the cold start valve 21 to open and control the supercharger bypass of the turbine 14 to open when the gas pressure data after the mixer 17 increases and the intake air flow data decreases after the throttle valve is closed, and also control the valve opening of the EGR valve 20 and the cold start valve 21 based on the intake air flow data, the oxygen concentration data in the exhaust gas of the turbine 14, the oxygen concentration data in the exhaust gas of the EGR-dedicated cylinder 11, the gas pressure data after the mixer 17, the gas temperature data after the mixer 17, and the valve opening signal of the cold start valve 21 and the valve opening signal of the EGR valve 20. In this preferred embodiment, the electronic control unit determines the corresponding acceleration value when the vehicle decelerates through the brake pedal signal, and when the acceleration value of the vehicle is smaller than the second set acceleration value, the vehicle can be determined to be in a rapid deceleration condition. It is understood that the electronic control unit may also acquire the acceleration value of the vehicle through an acceleration sensor and a radar device arranged on the vehicle.
During the rapid deceleration of the vehicle, the EGR rate is suddenly and rapidly reduced, the engine variable is increased, if the EGR device is directly and completely turned off, the engine dynamic property is rapidly reduced, the air intake amount is rapidly reduced, and meanwhile, the emission and the like are affected. Therefore, when the rapid deceleration of the special EGR aiming at a single cylinder (the single EGR special cylinder 11) is calibrated, the electronic control unit of the engine receives signals and then closes the throttle valve, so that the pressure behind the mixer 17 is increased, the air intake quantity is reduced, the electronic control unit outputs opening degree signals of the EGR valve 20 and the cold start valve 21 through the collected signals, meanwhile, a supercharger bypass channel is opened, signals on related parts and channels are fed back to the electronic control unit, the electronic control unit conducts verification, the opening degree of the cold start valve 21 is increased, exhaust gas of the EGR single cylinder is compensated to the channel of a normal cylinder, and the rapid deceleration operation is completed. Therefore, the engine can be in smooth transition in the process of sudden deceleration, and the vehicle pause feeling of a customer is effectively reduced.
The air flow sensor 1 is also used for collecting the intake air temperature data of the EGR device.
As shown in fig. 4, the electronic control unit is further configured to control the EGR valve 20, the cold start valve 21 and the throttle valve of the vehicle to open when the vehicle is determined to be in the low temperature cold start condition according to the engine start signal and the intake air temperature data of the vehicle, correct the valve opening of the EGR valve 20 according to the gas pressure data after the mixer 17, the gas temperature data after the mixer 17, the valve opening data of the EGR valve 20 and the oxygen concentration data in the exhaust gas of the EGR-dedicated cylinder 11 to reduce the cold start time of the EGR apparatus, and correct the valve opening of the cold start valve 21 according to the oxygen concentration data in the exhaust gas of the turbine 14 to achieve the rapid light-off of the catalyst 15.
Under the low-temperature cold start working condition (the starting working condition of lower than minus 7 ℃), the engine and the catalyst 15 have the requirement of quick ignition, when the engine is started, the temperature data of the intake flow sensor is reported to the electronic control unit, the electronic control unit opens the EGR valve 20, opens the throttle valve and opens the cold start valve 21, wherein the opening degree of the EGR valve 20 is about 30% in the opening stage, mainly the cold start valve 21 starts, and the quick ignition of the catalyst 15 is realized. Meanwhile, signals of related sensors on the EGR passage are fed back to the electronic control unit, the electronic control unit further opens the EGR valve 20 according to working condition feedback information, meanwhile, combustion parameters of the single cylinder are adjusted, combustion at the moment mainly raises the combustion temperature of exhaust gas instead of guaranteeing exhaust substances, so that the temperature of the engine is rapidly raised, and further cold start time is reduced.
The intake air flow sensor related to the embodiment of the invention not only aims at measuring the flow, but also integrates the temperature function, and the feedback signal to the electronic control unit comprises the intake air flow and the intake air temperature information. The main functions of the temperature-integrated air intake flow sensor in the system are to monitor air intake flow and ambient air intake temperature, to accurately monitor the working conditions and to feed back commands of the electronic control unit under specific transient working conditions.
The invention also provides a single-cylinder EGR control method of the engine, which is applied to the control system and comprises the following steps:
collecting air intake flow data of the EGR device through an air flow sensor 1;
acquiring oxygen concentration data in the exhaust gas of the turbine 14 by means of a first oxygen sensor 2;
acquiring oxygen concentration data in the exhaust gas of the EGR special cylinder 11 through a second oxygen sensor 3;
collecting gas pressure data after the mixer 17 through the first pressure sensor 5;
collecting gas temperature data after the mixer 17 through the first temperature sensor 6;
the method comprises the steps of calculating an EGR rate through an electronic control unit according to intake air flow data and oxygen concentration data in exhaust gas of an EGR special cylinder 11, adjusting valve opening degrees of a cold start valve 21 and an EGR valve 20 according to gas pressure data after a mixer 17 and gas temperature data after the mixer 17, correcting the EGR rate to confirm the position of the EGR gas, and performing ignition control (for example, adjusting the ignition angle and the oil injection time of an engine) on the engine according to the position of the EGR gas to realize accurate control of transient working conditions of the single-cylinder EGR device.
The single-cylinder EGR control method of the engine further comprises the following steps:
when the electronic control unit judges that the vehicle is in a rapid acceleration working condition according to an accelerator pedal signal of the vehicle, the electronic control unit controls the throttle valve of the vehicle to be opened, and controls the EGR valve 20 to be opened when the gas pressure data after the mixer 17 is reduced and the air inlet flow data is increased after the throttle valve is opened, controls the supercharger control valve of the turbine 14 to be opened, and determines the ignition angle and the oil injection time of the engine and the oil injection quantity of the EGR non-dedicated cylinders 8, 9 and 10 and the EGR dedicated cylinder 11 according to the oxygen concentration data in the exhaust gas of the turbine 14, the oxygen concentration data in the exhaust gas of the EGR dedicated cylinder 11, the gas pressure data after the mixer 17 and the gas temperature data after the mixer 17.
The single-cylinder EGR control method of the engine further comprises the following steps:
when the electronic control unit judges that the vehicle is in a rapid deceleration working condition according to a brake pedal signal of the vehicle, the electronic control unit controls the throttle valve of the vehicle to be closed, controls the valve opening of the EGR valve 20 to be reduced according to a set rate after the throttle valve is closed and controls the cold start valve 21 to be opened and controls the supercharger bypass of the turbine 14 to be opened when the gas pressure data after the mixer 17 is increased and the gas flow data is reduced, and also regulates the valve opening of the EGR valve 20 and the cold start valve 21 according to the gas flow data, the oxygen concentration data in the exhaust gas of the turbine 14, the oxygen concentration data in the exhaust gas of the EGR special cylinder 11, the gas pressure data after the mixer 17, the gas temperature data after the mixer 17, the valve opening signal of the cold start valve 21 and the valve opening signal of the EGR valve 20.
The single-cylinder EGR control method of the engine further comprises the following steps:
collecting intake air temperature data of an EGR device through an air flow sensor 1;
when the electronic control unit judges that the vehicle is in a low-temperature cold start working condition according to an engine start signal and intake air temperature data of the vehicle, the EGR valve 20, the cold start valve 21 and a throttle valve of the vehicle are controlled to be opened, the valve opening of the EGR valve 20 is corrected according to gas pressure data after the mixer 17, gas temperature data after the mixer 17, valve opening data of the EGR valve 20 and oxygen concentration data in exhaust gas of the EGR special cylinder 11, so that cold start time of the EGR device is shortened, and the valve opening of the cold start valve 21 is corrected according to the oxygen concentration data in the exhaust gas of the turbine 14, so that quick light-off of the catalyst 15 is realized.
The invention improves the problems of knocking and fire in the processes of rapid acceleration and rapid deceleration through the linkage control of two valve bodies (namely an EGR valve 20 and a cold start valve 21) in the system. Through increasing air flow sensor 1, the integrated temperature function of flow sensor simultaneously, through carrying out data acquisition to accelerograph pedal, air flow sensor and temperature, oxygen sensor, line oxygen sensor etc. passageway, carry out detailed EGR rate calculation according to the data of gathering, through the control of cooperateing to cold start valve 21 and EGR valve 20, carry out the control of angle of ignition, realize accurate combustion control.
In summary, the system and method provided by the present invention can acquire the intake air flow data of the EGR device by the air flow sensor 1, the oxygen concentration data in the exhaust gas from the turbine 14 by the first oxygen sensor 2, the oxygen concentration data in the exhaust gas from the EGR dedicated cylinder 11 by the second oxygen sensor 3, the gas pressure data after the mixer 17 by the first pressure sensor 5, and the gas temperature data after the mixer 17 by the first temperature sensor 6, when the data is acquired by each sensor, calculate the EGR rate by the electronic control unit based on the intake air flow data and the oxygen concentration data in the exhaust gas from the EGR dedicated cylinder 11, and calculate the EGR rate based on the gas pressure data after the mixer 17 and the gas temperature data after the mixer 17, the valve opening degrees of the cold start valve 21 and the EGR valve 20 are adjusted, the EGR rate is corrected to confirm the position of the EGR gas, the ignition angle and the oil injection time of the engine are determined according to the position of the EGR gas, the condition that the engine ignites in advance to cause knocking of the EGR non-special cylinders 8, 9 and 10 is avoided, the condition that fire occurs in the EGR non-special cylinders 8, 9 and 10 due to the fact that the over-concentrated EGR gas is guided into the EGR non-special cylinders 8, 9 and 10 under the condition of rapid deceleration is avoided, the problem of engine power reduction caused by over-high EGR rate can be avoided, and the accurate control of the transient working condition of the single-cylinder EGR device is achieved.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
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