CN209398491U - A control system that can effectively expand the efficient and clean operation range of gasoline compression ignition - Google Patents

Abstract

The utility model discloses a kind of control system that can effectively expand gasoline compression ignition high-efficiency cleaning range of operation, each cylinder air inlet of double variable valve actuator for air is all connected with inlet manifold gas outlet, and inlet manifold's air inlet connects compressor；Each cylinder exhaust port is all connected with exhaust main air inlet, and exhaust main exhaust outlet connects turbine, and air intake heater is arranged in inlet manifold, and air intake heater flow control valve is arranged in air intake heater air inlet；By pipeline parallel connection intercooler between air intake heater air inlet and exhaust outlet, intercooler flow control valve is arranged in intercooler air inlet；Air intake duct low pressure fuel injector device, intake air temperature sensor, in-cylinder direct-jet high pressure fuel injector, air intake heater, air intake heater flow control valve, intercooler flow control valve, EGR check valve and high pressure EGR valve are electrically connected with electronic control unit.It is high that the utility model solves the problems, such as that granule number existing for current in-cylinder direct-jet technology discharges.

Description

A control system that can effectively expand the efficient and clean operation range of gasoline compression ignition

technical field

The utility model relates to the field of internal combustion engines, and more specifically relates to a control system capable of effectively expanding the efficient and clean operation range of gasoline compression ignition.

Background technique

With the increasing number of automobiles, people pay more and more attention to their negative effects on energy and environment. Countries have also successively enacted more stringent emission regulations to limit the emission of harmful emissions and greenhouse gases such as CO ₂ . Therefore, it is of great significance to explore the control technology of high-efficiency and clean combustion of internal combustion engines for countries to achieve energy conservation and emission reduction.

The traditional gasoline engine is controlled by equivalence ratio combustion, and the aftertreatment can completely rely on a simple three-way catalyst. Because of its low cost and simple control, it is widely used. However, the load of the traditional gasoline engine is controlled by the throttle, and the pumping loss is relatively large under partial load conditions, and the compression ratio is low, resulting in low thermal efficiency. In order to meet the development trend of high efficiency and energy saving in the future, the control technology of "direct injection, stratified lean combustion" (GDI) has been widely used in gasoline engines at present. GDI directly controls the load through the fuel injection quantity and cancels the dependence on the throttle valve. ; The high injection pressure of GDI can make the fuel fully mixed with the air, so that the fuel can be burned more fully; the stratified lean mixture formed by GDI can enhance the ability to suppress knocking, and can appropriately increase the compression ratio. Therefore, GDI has higher thermal efficiency than traditional multi-point injection (MPI) gasoline engine. However, GDI also has shortcomings: first, studies have shown that the concentration of particles in GDI exhaust is more than 10 times that of traditional multi-point injection gasoline engines, mainly due to the short formation time of the mixture and the high injection pressure that makes the fuel hit the wall, etc. The reason is the formation of local high-temperature and over-rich areas, which lead to the formation of soot; secondly, in the GDI engine, the spark plug ignites and burns the mixed gas area is small, and the higher fuel injection pressure makes the air-fuel ratio at the boundary of mixed gas diffusion higher, so that the flame is in the direction of In the process of peripheral propagation, it gradually weakens, and even the flame propagation is interrupted, so that the mixed gas cannot be fully burned; finally, although GDI lean combustion is efficient and energy-saving, the air-fuel ratio is not close to the theoretical air-fuel ratio, so that the widely used three-way catalytic converter cannot work efficiently. .

A large number of studies have shown that improving the uniformity of the mixture before ignition can improve soot emissions; large-scale cooling of EGR can achieve ultra-low emission of NOx; increasing the compression ratio can improve fuel economy; coupling internal EGR and fuel injection strategy to adopt compression ignition The method can realize the stable combustion of gasoline under small load. Therefore, based on the above theories and aiming at the problems of GDI, the utility model proposes a control system and method that can effectively expand the high-efficiency and clean operation range of gasoline compression ignition.

Utility model content

The purpose of this utility model is to overcome the deficiencies in the prior art, provide a control system that can effectively expand the efficient and clean operation range of gasoline compression ignition, and solve the problem of high particle number emission in the current in-cylinder direct injection (GDI) technology. Problem: Solve the problem of unstable combustion at low load and rough work at high load in order to improve gasoline compression ignition.

The purpose of this utility model is achieved through the following technical solutions.

The control system of the utility model, which can effectively expand the high-efficiency and clean operation range of gasoline compression ignition, includes a double variable valve mechanism arranged in a compression ignition engine, and each cylinder air inlet of the double variable valve mechanism is connected with a Intake manifold, all intake manifolds are connected to the outlet of the intake manifold, the inlet of the intake manifold is connected to the exhaust port of the compressor, and the inlet of the compressor is connected to the air filter; the double can Each cylinder exhaust port of the variable valve mechanism is connected to an exhaust manifold, and all the exhaust manifolds are connected to the intake port of the exhaust manifold, and the exhaust port of the exhaust manifold is connected to the intake port of the turbine.

Each of the intake manifolds is provided with an intake port low-pressure fuel injector, the outlet of the intake manifold is provided with an intake air temperature sensor, and each cylinder of the double variable valve mechanism is provided with an in-cylinder Direct-injection high-pressure fuel injector; the intake manifold is provided with an intake heater, and the intake port of the intake heater is provided with an intake heater flow control valve, and the intake end of the intake heater is connected to An exhaust branch is connected between the intake main pipe and the exhaust main pipe, and the exhaust branch is provided with an EGR check valve and a high-pressure EGR valve; The pipeline is connected in parallel with an intercooler, and the air inlet of the intercooler is provided with an intercooler flow control valve;

The low-pressure fuel injector of the intake port, the intake air temperature sensor, the direct injection high-pressure fuel injector in the cylinder, the intake heater, the flow control valve of the intake heater, the flow control valve of the intercooler, the EGR check valve and the high pressure The EGR valves are electrically connected to the electronic control unit through signal lines.

The tube side of the intercooler is connected with the pipeline where it is located, and the cooling water inlet of the shell side of the intercooler is provided with a cooling water flow control valve of the intercooler, and the cooling water flow control valve of the intercooler communicates with the electronic The control unit is electrically connected.

The electronic control unit stores various control parameter target values and various control strategies under various working conditions. Internal injection oil quantity, in-cylinder injection timing, and in-cylinder injection pressure, the control strategies include dual-injection injection strategy, internal EGR strategy, external EGR strategy, intake valve strategy, exhaust valve strategy and intake air temperature control strategy .

Compared with the prior art, the beneficial effects brought by the technical solution of the utility model are:

(1) The gasoline of the utility model adopts the mode of compression ignition ignition, cancels the ignition system, and improves the reliability of the engine.

(2) The utility model adopts a dual-injection system to form as much premixed gas as possible before ignition, realize low-temperature combustion, effectively reduce NOx and soot (Soot) emissions, and cooperate with valve strategy and intake air temperature control strategy, can Clean combustion in the whole range of working conditions.

(3) The Miller cycle with a high geometric compression ratio of the utility model makes the engine have a higher expansion ratio in the range of all working conditions, so the thermal efficiency of the engine can be improved.

Description of drawings

Fig. 1 is a schematic diagram of the control system of the utility model that can effectively expand the high-efficiency and clean operation range of gasoline compression ignition;

Fig. 2 is a logic diagram of judging engine operating conditions of the present utility model;

Fig. 3 is the logic diagram of injection strategy (a), EGR strategy (b) and exhaust valve control strategy (c) of the present utility model;

Fig. 4 is a logic diagram of the intake air temperature control system of the present invention;

Fig. 5 is a logic diagram of the intake valve control strategy of the present invention.

Reference signs: 1 double variable valve mechanism, 2 direct injection high-pressure fuel injector in cylinder, 3 intake air temperature sensor, 4 intake port low-pressure fuel injector, 6 intake air heater, 7 intercooler cooling water flow control valve, 8 intercooler, 9 intake heater flow control valve, 10 intercooler flow control valve, 11 air filter, 12 EGR check valve, 13 high pressure EGR valve, 14 compressor, 15 turbine, ECU electronic control unit.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is further described.

As shown in Figure 1, the control system of the present invention, which can effectively expand the high-efficiency and clean operation range of gasoline compression ignition, includes a double variable valve mechanism 1, and the double variable valve mechanism 1 is arranged in a compression ignition engine. Compression ignition engines are reciprocating piston engines. The dual variable valve mechanism 5 can flexibly adjust the closing time of the intake valve in the full range of working conditions, and can also realize the double opening of the exhaust valve (the exhaust valve is additionally opened once during intake).

Each cylinder intake port of the double variable valve mechanism 1 is connected with an intake manifold, and all the intake manifolds are connected with the outlet of the intake manifold, and the intake port of the intake manifold is connected with the compressor 14 for exhaust. The air inlet of the compressor 14 is connected to the air filter 11 . Each cylinder exhaust port of the dual variable valve mechanism 1 is connected with an exhaust manifold, and all exhaust manifolds are connected with the intake port of the exhaust manifold, and the exhaust port of the exhaust manifold is connected with the intake port of the turbine 15. mouth. The compressor 14 and the turbine 15 are connected by a shaft. Each of the intake manifolds is provided with an intake port low-pressure fuel injector 4, the outlet of the intake manifold is provided with an intake air temperature sensor 3, and each cylinder of the double variable valve mechanism 1 is provided with a There are in-cylinder direct injection high-pressure fuel injectors 2.

The intake manifold is provided with an intake heater 6, the intake of the intake heater 6 is provided with an intake heater flow control valve 9, and the intake manifold connected to the intake end of the intake heater 6 An exhaust branch is connected with the exhaust main pipe, and the exhaust branch is provided with an EGR check valve 12 and a high-pressure EGR valve 13 . An intercooler 8 is connected in parallel through a pipeline between the air inlet and the exhaust port of the air intake heater 6, and the tube side of the intercooler 8 is connected to the pipeline where it is located, and the intercooler 8 takes in air An intercooler flow control valve 10 is provided at the mouth of the intercooler, and an intercooler cooling water flow control valve 7 is provided at the shell side cooling water inlet of the intercooler 8 .

The intake port low-pressure fuel injector 4, intake air temperature sensor 3, in-cylinder direct injection high-pressure fuel injector 2, intake heater 6, intercooler cooling water flow control valve 7, intake heater flow control valve 9. The flow control valve 10 of the intercooler, the EGR check valve 12 and the high-pressure EGR valve 13 are all electrically connected to the electronic control unit ECU through signal lines. The electronic control unit ECU stores various control parameter target values and various control strategies under various working conditions, and the control parameters include intake air temperature, intake and exhaust valve opening and closing timing, intake port injection oil volume, Injection oil quantity in cylinder, injection timing in cylinder, injection pressure in cylinder, the control strategy includes dual injection injection strategy, internal EGR strategy, external EGR strategy, intake valve strategy, exhaust valve strategy and intake air temperature control Strategy.

The intake air temperature of the engine can be monitored in real time by the intake air temperature sensor 3, and is passed through the air intake heater 6, the intercooler cooling water flow control valve 7, the intercooler 8, the intake air heater flow control valve 9, the intercooler The device flow control valve 10 realizes flexible adjustment. The in-cylinder direct-injection high-pressure injector 2 and the intake port low-pressure injector 4 form a dual-fuel injection system, and the fuel injection ratio between the intake port and the cylinder, the injection timing in the cylinder, and the injection pressure in the cylinder can all be controlled electronically. The control unit ECU performs flexible control. The double variable valve mechanism 5, the EGR check valve 12 and the high-pressure EGR valve 13 form an internal and external EGR system. The intake air temperature sensor 3, the intake air heater 6, the intercooler cooling water flow control valve 7, the intercooler 8, the intake air heater flow control valve 9, and the intercooler flow control valve 10 form an intake air temperature control valve. system.

The in-cylinder direct injection high-pressure fuel injector 2 and the intake port low-pressure fuel injector 4 in the dual fuel injection system are connected to the same fuel tank. The engine speed signal and accelerator pedal position signal are read by the electronic control unit ECU to judge the current operating condition of the engine (as shown in Figure 2), and execute the corresponding dual injection strategy, as shown in Figure 3 (a). In the light load condition, only the intake port injection is used, and the internal EGR with a higher temperature is coupled to make the high-concentration area of the mixture overlap with the high-temperature area, which is conducive to the stable ignition and combustion of gasoline; A dual-injection strategy that combines port injection and in-cylinder direct injection. A small proportion of locally over-rich mixture formed by in-cylinder direct injection is easily compressed and ignited, thereby igniting the premixed gas injected into the intake port to achieve a large proportion of premixed gas. Combustion is beneficial to reduce the emission of soot and particle number; under heavy load conditions, the injection ratio of the intake port is reduced to prevent the engine from being damaged due to an excessively high pressure rise rate.

The dual variable valve mechanism includes a variable intake valve system and a variable exhaust valve system. The variable intake valve system mainly uses the late closing strategy of the intake valve (Miller cycle) to ensure that the premixed gas formed by the injection of the intake port will not spontaneously ignite to achieve a greater effective compression ratio and ensure sufficient intake air. So as to achieve efficient and clean combustion. The closing time of the intake valve is closely related to the intake air temperature, and the control strategy of the intake valve is shown in Figure 5. First, the control unit ECU reads the speed and throttle position signals, judges the current engine operating conditions, and obtains the target intake air temperature and the optimal late closing time of the intake valve under this operating condition. The influence of the intake air temperature on the closing time of the intake valve will appear in the following three situations: (1) If the actual intake air temperature is within the target intake air temperature range (Flag=0), then the optimal closing time of the intake valve will be executed. If the intake air temperature control system cannot immediately make the intake air temperature reach the target temperature under variable working conditions or severe environmental conditions, the optimal intake valve closing time is corrected by the intake air temperature difference. (2) If the intake air temperature is greater than the maximum threshold of the target intake air temperature (Flag=1), execute the corresponding temperature difference (ΔT=T _a -T _th , T _a represents the actual temperature, and T _th represents the maximum threshold of the target temperature) intake valve closing time. If the temperature difference signal (ΔT _i+1 ) collected this time is greater than the previous temperature difference signal (ΔT _i ), the valve closing time will continue to be postponed; if ΔT _i+1 <ΔT _i , the intake valve closing time will be advanced; if ΔT _i+1 =ΔT _i , then the closing time of the intake valve remains unchanged. (3) If the intake air temperature is lower than the minimum threshold of the target intake air temperature (Flag=2), execute the intake valve closing time corresponding to the temperature difference (ΔT=T _tl- T _a , T _tl represents the minimum threshold of the target temperature) . If ΔT _i+1 > ΔT _i , the valve closing time is advanced; if ΔT _i+1 < ΔT _i , the intake valve closing time is delayed; if ΔT _i+1 = ΔT _i , the intake valve closing time remains unchanged . Therefore, through the above control strategy of the closing time of the intake valve, the normal combustion of the engine can be ensured under conditions where the intake air temperature is difficult to control, such as variable operating conditions or harsh environmental conditions, while ensuring high thermal efficiency.

The control strategy of the variable exhaust valve system is shown in Fig. 3(c). Under the condition of light load (State=1) or start-up (State=0), the strategy of opening the exhaust valve twice (except exhaust In addition to opening the exhaust valve during the stroke, open the exhaust valve once during the intake stroke) to achieve internal EGR, and adjust the opening time and duration of the second exhaust valve according to the temperature stratification to be achieved and the amount of internal EGR; If it is in the middle load (State=3) or heavy load (State=4) working condition, then adopt the normal one-time opening strategy of the exhaust valve.

The control strategy of the internal and external EGR system is shown in Figure 3 (b). In the light load or start-up condition, the internal EGR is used to ensure stable combustion in the light load condition; in the medium load or heavy load condition, the external cooling is used. EGR reduces the combustion temperature in the cylinder and realizes low NOx combustion. The external EGR system includes an EGR check valve 12 and a high-pressure EGR valve 13. EGR is discharged from the exhaust valve, passes through the high-pressure EGR valve 13 and the EGR check valve 12 in sequence, and after being mixed with fresh air, passes through the temperature control system and finally enters the Combustion in the engine.

The intake air temperature control system of the engine includes an intake air temperature sensor 3, an intake air heater 6, an intercooler cooling water flow control valve 7, an intercooler 8, an air intake heater flow control valve 9 and an intercooler flow control valve 10. The intake air temperature of the engine is measured by the intake air temperature sensor 3, and the control unit ECU obtains the target intake air temperature range under the operating condition according to the current working condition of the engine. The intake air temperature is controlled within the target intake air temperature range by the intake air heating control system. The control strategy of intake air temperature is shown in Fig. 4. There are three situations as follows: (1) If the intake air temperature is higher than the maximum threshold temperature, the intake air temperature will be reduced according to the following control method until the intake air temperature meets the requirements. First reduce the intake air heating power. When the heating power drops to zero, increase the opening of the intercooler gas flow control valve to allow a part of the gas to pass through the intercooler for cooling. When the intercooling gas flow control valve is fully opened, the opening of the heating gas flow control valve is reduced until the heating gas flow control valve is fully closed. If the intake air temperature is still high at this time, set Flag=1, and execute the late closing control strategy of the intake valve as shown in FIG. 4 . (2) If the intake air temperature is lower than the minimum threshold, increase the opening of the heating gas flow control valve, reduce the gas flow through the intercooler, and increase the intake air temperature. When the heating gas flow control valve is fully opened, the opening of the intercooler gas flow control valve is reduced to further reduce the gas flow passing through the intercooler and increase the intake air temperature. For the temperature range of the intercooler, set Flag=2, and execute the late closing strategy of the intake valve as shown in FIG. 4 . (3) If the intake air temperature is within the target intake air temperature range, set Flag=0. According to Figure 4, it is enough to execute the optimal closing time of the entry door under this working condition.

The utility model can realize the control method of gasoline high-premixing, high-efficiency, clean, compression-ignition and low-temperature combustion in the full range of working conditions. The electronic control unit ECU first reads the engine speed signal and the throttle position signal, judges the current operating condition of the engine, and determines the double injection of fuel. Strategy and internal and external EGR strategy, and then combined with the intake air temperature signal to determine the intake and exhaust valve strategy. The internal EGR and in-cylinder fuel injection are realized by opening the exhaust valve twice, and the local high-temperature rich mixture in the cylinder is organized to improve the combustion stability under low-load conditions; the late-closing strategy of the intake valve is used to couple external cooling EGR under high-load conditions. As well as the fuel injection strategy based on fuel port injection, the port injection fuel is compressed, heated and reformed, and a large proportion of pre-mixed low-temperature combustion is triggered by a small amount of direct injection fuel in the cylinder, suppressing the high load and excessive explosion pressure and NOx and Soot emission; so as to realize high-premix, high-efficiency, clean compression ignition and low-temperature combustion of gasoline in the full range of working conditions.

The utility model can also make some simple deductions or replacements. For example, the above has only described the use of gasoline fuel. It should be regarded as belonging to the protection scope of the utility model patent.

Claims (3)

1. a kind of control system that can effectively expand gasoline compression ignition high-efficiency cleaning range of operation, including it is set to compression ignition engine Each cylinder air inlet of interior double variable valve actuator for air (1), double variable valve actuator for air (1) is respectively connected with inlet manifold, All inlet manifold are all connected with inlet manifold gas outlet, and inlet manifold's air inlet connects compressor (14) exhaust outlet, described Compressor (14) air inlet connects air cleaner (11)；Each cylinder exhaust port of double variable valve actuator for air (1) connects It is connected to exhaust manifold, all exhaust manifolds are all connected with exhaust main air inlet, and the exhaust main exhaust outlet connects turbine (15) air inlet, which is characterized in that

Be provided with air intake duct low pressure fuel injector device (4) in each inlet manifold, the inlet manifold gas outlet be provided with into Gas temperature sensor (3) is provided with in-cylinder direct-jet high pressure fuel injector in each cylinder of double variable valve actuator for air (1) (2)；The inlet manifold is provided with air intake heater (6), and air intake heater (6) air inlet is provided with air intake heater stream Control valve (9) is connected with exhaust branch between the inlet manifold and exhaust main of air intake heater (6) the inlet port connection Road, the exhaust branch are provided with EGR check valve (12) and high pressure EGR valve (13)；The air inlet of the air intake heater (6) and It is parallel with intercooler (8) between exhaust outlet by pipeline, intercooler (8) air inlet is provided with intercooler flow control valve (10)；

The air intake duct low pressure fuel injector device (4), intake air temperature sensor (3), in-cylinder direct-jet high pressure fuel injector (2), inlet air heating Device (6), air intake heater flow control valve (9), intercooler flow control valve (10), EGR check valve (12) and high pressure EGR valve (13) it is electrically connected by signal wire with electronic control unit ECU.

2. the control system according to claim 1 that can effectively expand gasoline compression ignition high-efficiency cleaning range of operation, feature It is, intercooler (8) tube side pipeline where with it is connected, during intercooler (8) the shell side cooling water inlet is provided with Cooler cooling water flow control valve (7), the intercooler cooling water flow control valve (7) pass through signal wire and electronic control unit ECU electrical connection.

3. the control system according to claim 1 that can effectively expand gasoline compression ignition high-efficiency cleaning range of operation, feature It is, the electronic control unit ECU stores control parameter target value and control strategy, and the control parameter includes air inlet temperature Degree, inlet and exhaust valve are opened and closed moment, intake port injection oil mass, cylinder injection oil mass, cylinder injection timing, cylinder injection pressure, institute State injection strategy, the internal EGR strategy, outside EGR strategy, inlet valve strategy, exhaust valve strategy that control strategy includes double injections With intake air temperature control strategy.