Variable intake and high and low temperature egr system for low carbon, zero carbon fuel engine facing mixed gas active reforming

Abstract

The application aims to provide a low-carbon and zero-carbon fuel engine variable intake and high-low temperature EGR system for mixed gas active reforming, which comprises an exhaust turbine, a compressor, a cylinder, an intake manifold, an exhaust manifold, a low temperature EGR circuit and a radiator, the cylinder is connected with the intake manifold and the exhaust manifold respectively, the intake manifold is connected with the intake manifold, the exhaust manifold is connected with the exhaust manifold, the intake manifold is connected with the compressor through the intercooler, the exhaust manifold is connected with the exhaust turbine and the low temperature EGR circuit respectively, the low temperature EGR circuit is connected with the Laval mixer at the end, the two ends of the Laval mixer are communicated with the atmosphere and the compressor respectively, the EGR cooler and the EGR flow regulating valve are arranged on the low temperature EGR circuit, the radiator is connected with the EGR cooler through the water inlet pipe and the water outlet pipe respectively, and the pump is arranged on the water outlet pipe. The application can realize the application of multiple modes to face different working conditions of different types of engines, and realize the performance optimization of the engine under the full working condition through the intake and exhaust valve control coupled EGR regulation.

Description

TECHNICAL FIELD

[0001] The present application relates to an engine exhaust system, in particular to an engine exhaust gas recirculation system. BACKGROUND

[0002] In the process of navigation of a ship, a large amount of harmful gas is discharged, the main components of which are NO X , SO X , HC, harmful particulate matter and the like. With the gradual increase of the cost of sailing, people will choose some inferior fuel, which further aggravates the emission of pollutants of the ship. When the engine is in high working condition, the adiabatic flame temperature in the cylinder is relatively high, and a large amount of nitrogen oxides will be generated under the condition of sufficient oxygen; when the engine is in low working condition, the temperature in the cylinder is low, and the fuel consumption rate increases due to incomplete combustion, cold-wall flame quenching, gap effect and other reasons, and a large amount of hydrocarbons is generated. Therefore, how to realize high efficiency and low emission of the engine under different working conditions becomes a major problem.

[0003] Exhaust gas recirculation technology (EGR) is one of the key technologies commonly used in the field of internal combustion engine to reduce NOx emission. The EGR technology sends part of the exhaust gas generated by the internal combustion engine into the intake pipe. Since the exhaust gas contains a large amount of multi-atomic gas with high specific heat capacity, it can reasonably utilize the high specific heat capacity of the exhaust gas to effectively absorb the heat generated by combustion and reduce the temperature in the cylinder, thereby greatly reducing the generation of NO X . There are two methods to realize the EGR technology. One is to introduce the exhaust gas into the intake pipe through an external EGR pipeline, which is called external EGR. The other is to change the scavenging process through variable valve timing technology to allow part of the exhaust gas to remain in the cylinder, which is called internal EGR technology. The external EGR can reduce the temperature of the exhaust gas due to the action of the intercooler, and the cooled exhaust gas mixed with fresh air can obtain low-temperature exhaust gas. In high working condition, the combustion temperature can be effectively reduced to reduce NO X emission. However, in low working condition, the injection amount is small, and the power of turbocharging is reduced, resulting in less intake air. If the cooled EGR is continued to be introduced, the combustion effect will be further deteriorated, and the fuel consumption rate will be increased. By using variable valve timing technology, high-temperature EGR can be retained by early closing of the exhaust valve, which can effectively preheat the combustion and promote the combustion, thereby effectively solving the short board of external EGR in low working condition. By combining the external EGR technology and the variable valve timing technology and using collaborative control means, different quality EGR can be realized under different load conditions, thereby realizing high efficiency and low emission of the diesel engine under different working conditions. SUMMARY

[0004] The present application aims to provide a variable intake and high-low temperature EGR system for low-carbon and zero-carbon fuel engines using mixed gas active reforming by combining external EGR technology and variable valve timing technology.

[0005] The object of the present application is achieved in that:

[0006] The variable intake and high and low temperature EGR system for low carbon and zero carbon fuel engine of mixed gas active reforming, characterized by comprising an exhaust turbine, a compressor, a cylinder, an intake manifold, an exhaust manifold, a low temperature EGR circuit, a radiator, the exhaust turbine and the compressor being coaxial, the cylinder being connected with the intake manifold and the exhaust manifold respectively, the intake manifold being connected with the intake manifold, the exhaust manifold being connected with the exhaust turbine and the low temperature EGR circuit respectively, the low temperature EGR circuit being connected with the exhaust turbine and the low temperature EGR circuit at the end, the two ends of the exhaust turbine being connected with the atmosphere and the compressor respectively, the EGR cooler and the EGR flow regulating valve being arranged on the low temperature EGR circuit, the radiator being connected with the EGR cooler through the water inlet pipe and the water outlet pipe, and the pump being arranged on the water outlet pipe.

[0007] The present application can also include:

[0008] 1. The ECU and the rotating speed signal disc are further included, the intake valve and the exhaust valve are arranged on the cylinder respectively, the intake valve and the exhaust valve are connected with the hydraulic drive system, the rotating speed signal disc is installed on the engine crankshaft below the cylinder, the exhaust back pressure valve is arranged on the exhaust manifold before the inlet of the exhaust turbine, and the ECU is connected with the EGR flow regulating valve, the exhaust back pressure valve, the rotating speed signal disc and the hydraulic drive system respectively.

[0009] 2. The intake valve comprises a valve core and a valve, the valve core is connected with the valve, the valve core is located in the oil cavity, the oil cavity is separated into the upper oil cavity and the lower oil cavity by the valve core, the upper oil cavity is connected with the high pressure oil source through the first high pressure oil pipe and the second high pressure oil pipe respectively, the high pressure electromagnetic valve is arranged on the first high pressure oil pipe, and the upper oil cavity is connected with the low pressure oil source through the low pressure oil pipe, and the low pressure electromagnetic valve is arranged on the low pressure oil pipe.

[0010] 3. The exhaust valve is the same as the intake valve.

[0011] 4. When the engine is in the low load operation condition, the exhaust valve control high temperature EGR mode is implemented, the EGR flow regulating valve is completely closed, the EGR cooling system does not work, the exhaust back pressure valve is completely opened, the exhaust valve is closed in advance, the exhaust valve controls the mass of the exhaust gas remaining in each cylinder in the variable timing mode, the exhaust valve is closed in advance to prevent the exhaust gas from flowing out and to ensure the EGR in-cylinder remaining, the intake valve is delayed to open to prevent the backflow of the high temperature exhaust gas, and the intake valve is delayed to close to realize the Miller cycle under the premise that the intake mass is sufficient.

[0012] 5. When the engine is under heavy load, the universal low-temperature EGR mode is implemented. The exhaust back pressure valve is completely closed, the EGR flow regulating valve is opened, and the EGR cooling system starts to work. The opening degree of the EGR flow regulating valve and the heat exchange medium flow of the EGR cooling system are regulated by the ECU controller. The exhaust back pressure valve is kept at a large opening, thereby achieving the supply of external low-temperature EGR under high load conditions.

[0013] 6. When the engine is operating under medium to high operating conditions, a high and low temperature EGR coupling control mode is implemented. The exhaust valve, exhaust back pressure valve, EGR flow regulating valve, and EGR cooling system are all controlled by the ECU controller. The high temperature EGR quality in the cylinder is regulated by adjusting the exhaust valve opening timing, and the low temperature EGR quality in the intake manifold is regulated by controlling the EGR flow regulating valve and the EGR cooling system. The opening degree of the exhaust back pressure valve is used to regulate the ratio of high temperature EGR and low temperature EGR. Finally, the low temperature EGR and high temperature EGR are mixed in the cylinder to ensure stepless adjustment of EGR at different temperatures and quality levels.

[0014] The advantages of this invention are:

[0015] 1. This invention adopts integrated control of exhaust back pressure valve, intake and exhaust valve timing control, and EGR cooling system, which can be applied to various engines under all operating conditions.

[0016] 2. The method of coordinating the opening of the exhaust back pressure valve and the closing timing of the intake valve can achieve precise capture of high-temperature EGR in the engine; at the same time, the exhaust back pressure valve is used to increase the exhaust back pressure, which greatly reduces the difficulty of capturing high-temperature EGR and can effectively expand the adjustment range of EGR.

[0017] 3. The delayed opening of the intake valve provides sufficient expansion time for the high-temperature exhaust gas in the cylinder, which can prevent the backflow of exhaust gas caused by high cylinder pressure during the intake process; at the same time, it works together with the delayed closing of the intake valve to ensure sufficient intake volume and realize Miller cycle, effectively reducing the engine's compression work and improving engine thermal efficiency.

[0018] 4. The intake and exhaust valves are controlled by a hydraulic transmission system. This not only allows for adjustment of valve timing according to actual working conditions, but also effectively reduces the time required for the flow area to develop during the valve opening or closing process, thus effectively avoiding pumping losses. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention;

[0020] Figure 2 This is a schematic diagram of a variable valve timing system.

[0021] Figure 3The valve timing map for exhaust valve control high temperature EGR mode;

[0022] Figure 4 The valve timing map for general low temperature EGR mode and high-low temperature EGR coupling control mode;

[0023] Figure 5 The valve lift comparison curve for electro-hydraulic control and mechanical control. DETAILED DESCRIPTION

[0024] The application will be described in more detail below with examples and with reference to the accompanying drawings:

[0025] In combination Figures 1-5 , the application is composed of a cylinder 12, an intake manifold 16, an exhaust manifold 7, a throttle valve 17, an intercooler 18, an intake valve 11, an exhaust valve 10, a hydraulic drive system 9, a low temperature EGR circuit, an EGR cooling system, an EGR flow regulating valve 4, a turbocharger, an exhaust back pressure valve 6, a Laval mixer 20, an air filter 19, an ECU controller 14, etc. The intake valve 11 and the exhaust valve 10 of the variable intake system are connected with the hydraulic drive system 9, and the adaptive control of the intake and exhaust process of the cylinder 12 is realized by controlling the hydraulic drive system 9 through the ECU controller 14, so that the engine cycle and the high temperature exhaust gas can be changed. The inlet of the supercharger 21 of the turbocharger is connected with the Laval mixer 20 and the air filter 19 in sequence through a pipeline, the outlet of the compressor of the turbocharger is connected with the intercooler 18, the throttle valve 17 and the intake manifold 16 in sequence, and the inlet of the exhaust turbine 5 of the turbocharger is connected with the exhaust back pressure valve 6 and the exhaust manifold 7 in sequence. The inlet of the low temperature EGR circuit is connected with the exhaust manifold 7, and the interface is located between the exhaust back pressure valve 6 and the exhaust manifold 7. The outlet of the low temperature EGR circuit is connected with the throat of the Laval mixer 20. The low temperature EGR circuit is arranged with the low temperature EGR flow regulating valve 4 and the EGR cooling system in sequence along the gas flow direction. The ECU controller 14 is connected with the hydraulic drive system 9, the exhaust back pressure valve 6 and the EGR flow regulating valve 4, so as to realize the coordinated control of different valve openings under different working conditions. The variable intake system and the low temperature EGR circuit can realize the coupling control of the valve timing and the high-low temperature EGR under different load conditions, realize the regulation and control of the in-cylinder thermal atmosphere through the control of the intake and exhaust, and realize the performance optimization of the engine under the full working condition by reforming the activity of the mixture combined with the fuel injection strategy.

[0026] The hydraulic drive system is composed of a high-pressure oil source 22, a low-pressure oil source 27, a valve core 25, an oil cavity 30, a valve 26, a pressure chamber, a high-pressure electromagnetic valve 24 and a low-pressure electromagnetic valve 29. The valve core 25 is connected with the valve 26 by welding, and the valve core 25 is installed inside the oil cavity 30. An oil inlet hole is processed on one side of the valve 26 of the oil cavity 30, and the oil inlet hole is connected with the high-pressure oil source 22. A low-pressure oil hole and a high-pressure oil hole are processed on the other side of the oil cavity 30, and the low-pressure oil hole and the high-pressure oil hole are connected with the low-pressure oil source 27 and the high-pressure oil source 22 through the low-pressure electromagnetic valve 29 and the high-pressure electromagnetic valve 24 respectively. The hydraulic drive system 9 is controlled by the ECU controller 14. The control mode is that the hydraulic drive system 9 is controlled by the ECU controller 14 in a normal state, the low-pressure electromagnetic valve 29 is opened, the high-pressure electromagnetic valve 24 is closed, the valve 26 has high oil pressure on one side, and the valve 26 is closed. When the valve 26 needs to be opened, the low-pressure electromagnetic valve 29 is closed, the high-pressure electromagnetic valve 24 is opened, the oil pressure on both sides of the oil cavity 30 is equal, but the acting area of the valve 26 side is relatively small, the valve core 25 drives the valve to move downward, and the valve 26 is opened.

[0027] The EGR cooling system is composed of an EGR cooler 1, a pump 2 and a radiator 3. The inlet of the EGR cooler 1 is connected with the outlet of the radiator 3 through a pipeline, the outlet of the EGR cooler 1 is connected with the inlet of the radiator 3 through a pipeline in sequence, the EGR cooler 1 cools the gas in the low-temperature EGR circuit, and the radiator 3 releases the heat absorbed from the low-temperature EGR circuit to the environment. The pump 2 is controlled by the ECU controller 14, and corresponding heat exchange working medium is supplied according to different working conditions and different EGR flow rates, so that the EGR temperature at the outlet of the low-temperature EGR circuit is stably maintained at a target temperature.

[0028] As shown in Figure 1 The intake air of the engine is composed of two parts, one part is fresh air from the atmosphere, and the other part is exhaust gas from the low-temperature EGR circuit. The fresh air passes through the air filter 19, and the two kinds of gases are mixed through the Laval mixer 20 and then enter the supercharger 21 for compression. The compressed intake air is cooled through the intercooler 18, and then enters the intake manifold 16 through the throttle valve 17, and then enters each intake manifold 15. In the intake stroke, the intake valve 11 is opened by the hydraulic drive system 9, the gas enters the cylinder, and then enters the exhaust stroke after doing work. The exhaust valve 10 is opened by the hydraulic drive system 9, the exhaust gas enters the exhaust manifold 8, and then the exhaust gas is collected into the exhaust manifold 7. The high-temperature exhaust gas has two flow paths. One of them: the high-temperature exhaust gas enters the exhaust turbine 5 after passing through the exhaust back pressure valve 6 to expand and do work, so as to pressurize the incoming air. The other flow path: the high-temperature exhaust gas enters the low-temperature EGR circuit.

[0029] As shown in Figure 1As shown in the low-temperature EGR circuit, along the exhaust gas flow direction, respectively provided with EGR flow regulating valve 4 and EGR cooler 1, high-temperature exhaust gas into the low-temperature EGR circuit, flow through the EGR cooler 1, the heat transfer medium in the radiator 3 through the pump 2 into the EGR cooler 1, the high-temperature exhaust gas of the low-temperature EGR circuit is cooled, so as to obtain low-temperature exhaust gas, realize low-temperature EGR, the outlet of the low-temperature EGR circuit is connected with the Laval mixer 20, the above-mentioned pump 2 is controlled by the ECU controller 14, the flow of the pump 2 is controlled, so as to control the high-temperature exhaust gas to be cooled to a certain temperature.

[0030] As Figure 2 The variable valve timing system is mainly composed of high-pressure oil source 22, low-pressure oil source 27, valve core 25, oil cavity 30, valve 26, high-pressure oil pipe 23, low-pressure oil pipe 28, high-pressure electromagnetic valve 24 and low-pressure electromagnetic valve 29. Valve opening process: because the pressure acting area of the upper side of the oil cavity 30 is larger than that of the lower side, after the high-pressure electromagnetic valve 24 receives the control signal from the ECU controller 14 and opens, the valve core 25 moves downward in the environment of the pressure difference between the upper and lower sides, and drives the valve 26 to open. Valve closing process: after the low-pressure electromagnetic valve 29 receives the control signal from the ECU controller 14 and opens, the hydraulic oil on the upper side of the oil cavity 30 flows to the low-pressure oil source 27 through the low-pressure electromagnetic valve 29 and the low-pressure oil pipe 28, so that the pressure in the chamber at the upper end of the piston is reduced, and thus the valve core drives the valve to move upward under the action of the pressure difference, so that the valve is closed. The lift and phase of the valve are determined by the control signal of the ECU controller 14, so as to realize the full variable valve lift and valve phase. The valve lift curve diagram of mechanical control and electro-hydraulic control is as shown in Figure 5 The intake and exhaust valves are controlled by the electro-hydraulic drive system, which has the advantages of fast response, wide speed regulation range and easy control compared with the traditional mechanical cam control, and is not limited by the mechanical structure, so that the intake and exhaust valves driven by the electro-hydraulic drive system can be quickly opened and seated, and the valve lift is stable.

[0031] As shown in Figure 1 The engine crankshaft is provided with a speed signal disc 13. The EGR flow regulating valve 4, the exhaust back pressure valve 6, the hydraulic drive system 9 and the pump 2 are controlled by the ECU controller 14, which obtains the engine speed signal from the speed signal disc 13, processes the signal through the ECU controller 14, and sends the signal to the EGR flow regulating valve 4, the exhaust back pressure valve 6, the hydraulic drive system 9 and the pump 2. Through the control process of each device, different EGR supply modes can be realized according to the type and operating state of the engine to optimize the performance of the engine under all operating conditions. The realization modes of different modes are as follows:

[0032] (1) Exhaust valve control high temperature EGR mode: this mode is suitable for low load engine operating conditions, the mode of valve timing diagram as shown in Figure 3 EGR flow regulating valve 4 is completely closed, EGR cooling system does not work, exhaust back pressure valve 6 is completely opened, adjusting ECU controller 14 makes exhaust valve 10 advance closing, using variable timing exhaust valve 10 accurately control the quality of the exhaust gas remaining in each cylinder, exhaust valve 10 advance closing prevents the flow of exhaust gas to ensure the EGR cylinder residual; using intake valve 11 delay opening, prevent the backflow of high temperature exhaust gas; intake valve 11 delay closing, ensure the premise of sufficient air quality to achieve Miller cycle, reduce the engine compression work loss.

[0033] (2) General low temperature EGR mode: this mode is suitable for engine high load operating conditions, the mode of valve timing as shown in Figure 4 Exhaust back pressure valve 6 is completely closed, EGR flow regulating valve 4 is opened, EGR cooling system starts to work, EGR flow regulating valve 4 opening and EGR cooling system heat transfer working fluid flow is adjusted according to the actual working condition by ECU controller 14, exhaust back pressure valve 6 is kept at a larger opening, so as to realize the supply of external low temperature EGR under the condition of high load; can realize the flow control of low temperature EGR, reduce the temperature rise rate of cylinder gas in the combustion process, reduce the emission of NOx, effectively avoid engine knock and rough work.

[0034] (3) High and low temperature EGR coupling control mode: this mode is suitable for engine medium and high operating conditions, different control strategies are adopted for different requirements of different conditions, the mode of valve timing as shown in Figure 4 Exhaust valve 10, exhaust back pressure valve 6, EGR flow regulating valve 4, EGR cooling system are controlled by ECU controller 14 in flexible adjustment state, using exhaust valve 10 opening timing adjustment to realize the adjustment of the quality of high temperature EGR in cylinder, using EGR flow regulating valve 4 and EGR cooling system control to realize the adjustment of low temperature EGR quality in intake port, and cooperate with exhaust back pressure valve 6 opening control to realize the regulation of high temperature EGR and low temperature EGR ratio, finally low temperature EGR and high temperature EGR are mixed in cylinder to ensure stepless adjustment of EGR under different temperature and quality level.

Claims

1. A low carbon, zero carbon fuel engine variable intake and high and low temperature EGR system for mixed gas active reforming, characterized in that: The exhaust turbine, the compressor, the cylinder, the intake manifold, the exhaust manifold, the low-temperature EGR circuit, the radiator, the exhaust turbine and the compressor are coaxial, the cylinder is connected with the intake manifold and the exhaust manifold respectively, the intake manifold is connected with the intake manifold, the exhaust manifold is connected with the exhaust manifold, the intake manifold is connected with the compressor through the intercooler, the exhaust manifold is connected with the exhaust turbine and the low-temperature EGR circuit respectively, the low-temperature EGR circuit is connected with the end of the Laval mixer, the two ends of the Laval mixer are communicated with the atmosphere and the compressor respectively, the EGR cooler and the EGR flow regulating valve are arranged on the low-temperature EGR circuit, the radiator is connected with the EGR cooler through the water inlet pipe and the drain pipe, and the pump is arranged on the drain pipe; The ECU and the rotating speed signal disc are further arranged, the intake valve and the exhaust valve are arranged on the cylinder respectively, the intake valve and the exhaust valve are connected with the hydraulic drive system, the rotating speed signal disc is installed on the engine crankshaft below the cylinder, the exhaust back pressure valve is arranged on the exhaust manifold before the inlet of the exhaust turbine, and the ECU is connected with the EGR flow regulating valve, the exhaust back pressure valve, the rotating speed signal disc and the hydraulic drive system. When the engine is in the low-load operation condition, the exhaust valve control high-temperature EGR mode is implemented, the EGR flow regulating valve is completely closed, the EGR cooling system does not work, the exhaust back pressure valve is completely opened, the exhaust valve is closed in advance, the exhaust valve control regulates the exhaust gas remaining in each cylinder, the exhaust valve closing in advance prevents the outflow of the exhaust gas and guarantees the in-cylinder remaining of the EGR, the intake valve is delayed to open, the backflow of the high-temperature exhaust gas is prevented, and the intake valve is delayed to close, so that the Miller cycle is realized under the premise that the intake mass is sufficient.

2. The low carbon, zero carbon fuel engine variable intake and high and low temperature EGR system for mixed gas active reforming of claim 1, characterized by: The intake valve comprises a valve core and a valve, the valve core is connected with the valve, the valve core is located in the oil chamber, the oil chamber is separated into upper and lower oil chambers by the valve core, the upper oil chamber is connected with the high-pressure oil source through the first high-pressure oil pipe, the lower oil chamber is connected with the high-pressure oil source through the second high-pressure oil pipe, the high-pressure electromagnetic valve is arranged on the first high-pressure oil pipe, and the upper oil chamber is connected with the low-pressure oil source through the low-pressure oil pipe.

3. The low carbon, zero carbon fuel engine variable intake and high and low temperature EGR system for mixed gas active reforming of claim 2, characterized by: The exhaust valve has the same structure as the intake valve.

4. The low carbon, zero carbon fuel engine variable intake and high and low temperature EGR system for mixed gas active reforming of claim 1, wherein: When the engine is in the high-load condition, the general low-temperature EGR mode is implemented, the exhaust back pressure valve is completely closed, the EGR flow regulating valve is opened, the EGR cooling system starts to work, the opening degree of the EGR flow regulating valve and the heat exchange medium flow of the EGR cooling system are controlled by the ECU controller, and the exhaust back pressure valve is kept at a larger opening degree, so that the external low-temperature EGR supply under the higher load condition is realized.

5. The low carbon, zero carbon fuel engine variable intake and high and low temperature EGR system for mixed gas active reforming of claim 1, wherein: When the engine is in the medium-high operation condition, the high-low temperature EGR coupling control mode is implemented, the exhaust valve, the exhaust back pressure valve, the EGR flow regulating valve and the EGR cooling system are controlled by the ECU controller, the adjustment of the opening time of the exhaust valve is adopted to realize the regulation of the in-cylinder high-temperature EGR mass, the control of the EGR flow regulating valve and the EGR cooling system is adopted to realize the regulation of the low-temperature EGR mass in the intake port, and the opening degree control of the exhaust back pressure valve is adopted to realize the regulation of the high-temperature EGR and the low-temperature EGR, so that the low-temperature EGR and the high-temperature EGR are mixed in the cylinder, and the stepless regulation of the EGR under different temperature and mass levels is realized.

Images