CN207686871U - The high pressure cold end egr system of engine - Google Patents

Abstract

The utility model discloses a high-pressure cold-end EGR system of an engine. The high-pressure cold-end EGR system of the engine includes: EGR cooler, which is respectively provided with exhaust gas passage and coolant passage, the intake end of the exhaust gas passage is connected with the exhaust pipe before the turbine of the supercharger, and the exhaust gas is transferred from the booster to the exhaust pipe. The exhaust pipe in front of the turbine of the compressor is cooled by heat exchange; the EGR valve, its inlet end is connected with the outlet end of the exhaust gas channel of the EGR cooler; the EGR mixer, its exhaust gas inlet is connected with the EGR The air outlet of the valve is connected, the air inlet of the EGR mixer is connected with the engine intake system; and the controller. The high-pressure cold-end EGR system of this engine has relatively few connecting pipes, which does not cause pollution to the intercooler and supercharger, and the change of exhaust back pressure does not directly affect the EGR exhaust gas flow, and the transient response is good. Moreover, the requirements for the heat resistance of the EGR valve are lower, and the cost is lower; the arrangement of the EGR valve is relatively easy.

Description

Engine high pressure cold end EGR system

technical field

The utility model relates to the field of engines, in particular to a high-pressure cold-end EGR system of the engine.

Background technique

Exhaust Gas Recirculation (EGR, Exhaust Gas Recirculation) is an effective measure to reduce the generation of NOx gas in the engine cylinder. The system is mainly composed of EGR valve, EGR cooler, check valve (optional), connecting pipeline and controller. Its working principle is: send part of the exhaust gas of the diesel engine back to the engine cylinder after cooling, and participate in the combustion process. The main components in the exhaust gas are CO2, H2O, N2, etc. Among them, the triatomic gases CO2 and H2O with higher specific heat capacity increase the cylinder capacity. The specific heat capacity of the internal mixture reduces the temperature in the cylinder before the ignition of the combustible mixture, and also reduces the temperature of the combustion process; at the same time, after the introduction of EGR, the oxygen content of the mixture in the cylinder decreases, which reduces the combustion rate and heat release rate. This series of effects can effectively reduce the formation of NOx emissions.

Structurally, it is divided into internal EGR and external EGR. The so-called internal EGR is to keep a part of the exhaust gas from being discharged from the cylinder, and dilute the mixture before the next combustion starts. The internal EGR is controlled by the phase of the intake and exhaust valves, that is, adjusted by the valve train. Generally speaking, EGR refers to external EGR, and the utility model is mainly applicable to the design of external EGR.

The existing external EGR system adopts low-pressure EGR, and the exhaust gas of this low-pressure EGR system generally takes EGR exhaust gas from behind the DPF and returns to the front of the supercharger compressor. The disadvantages of this low-pressure EGR system are: 1. There are many connecting pipelines, and an exhaust throttle valve is needed to control the pressure difference of exhaust gas flow. 2. If the particle filter is not installed, it will easily pollute the intercooler and supercharger and cause damage. 3. The change of exhaust back pressure directly affects the EGR exhaust gas flow, and the transient response is poor.

The information disclosed in this background section is only intended to increase the understanding of the general background of the present invention, and should not be considered as an acknowledgment or in any form to imply that the information constitutes the prior art already known to those skilled in the art.

Utility model content

The purpose of the utility model is to provide a high-pressure cold-end EGR system of an engine with a simple and reasonable structure. The exhaust gas of the high-pressure cold-end EGR system of the engine is drawn from the exhaust pipe in front of the turbocharger turbine, and the exhaust gas is first cooled by EGR. It enters the EGR valve after the cooler is cooled, has relatively few connecting pipelines, does not cause pollution to the intercooler and the supercharger, and the change of the exhaust back pressure does not directly affect the flow of the EGR exhaust gas, and the transient response is good. Moreover, the requirements for the heat resistance of the EGR valve are lower, and the cost is lower; the arrangement of the EGR valve is relatively easy.

In order to achieve the above object, the utility model provides a high-pressure cold end EGR system of the engine, comprising: an EGR cooler, which is respectively provided with an exhaust gas channel and a coolant channel, and the intake end of the exhaust gas channel is connected to the supercharger The exhaust pipe before the turbine is connected, and the exhaust gas is drawn out from the exhaust pipe before the turbine of the supercharger and then cooled by heat exchange; the EGR valve, whose inlet end is connected with the outlet end of the exhaust gas channel of the EGR cooler EGR mixer, its waste gas inlet is connected with the outlet end of the EGR valve, the air inlet of the EGR mixer is connected with the engine intake system; and the controller, which is integrated in the engine ECU, is used to and air intake demand control the opening of the EGR valve.

Preferably, in the above technical solution, the EGR cooler is a shell-and-tube cooler or a plate-fin cooler.

Preferably, in the above technical solution, a check valve is further provided between the EGR cooler and the EGR valve.

Preferably, in the above technical solution, the engine is a gas engine.

Preferably, in the above technical solution, the air inlet of the EGR mixer is connected downstream of the intercooler of the engine intake system.

Preferably, in the above technical solution, the EGR valve is made of cast aluminum.

Compared with the prior art, the utility model has the following beneficial effects: the exhaust gas of the high-pressure cold end EGR system of the engine is drawn from the exhaust pipe in front of the turbocharger turbine, and the exhaust gas is first cooled by the EGR cooler before entering the EGR The valve, with relatively few connecting pipelines, does not cause pollution to the intercooler and supercharger, and the change of exhaust back pressure does not directly affect the flow of EGR exhaust gas, and the transient response is good. Moreover, the requirements for the heat resistance of the EGR valve are lower, and the cost is lower; the arrangement of the EGR valve is relatively easy.

Description of drawings

FIG. 1 is a schematic structural view of the high-pressure cold-end EGR system of the engine of the present invention.

Detailed ways

The specific embodiments of the present utility model will be described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present utility model is not limited by the specific embodiments.

Unless expressly stated otherwise, throughout the specification and claims, the term "comprise" or variations thereof such as "includes" or "includes" and the like will be understood to include the stated elements or constituents, and not Other elements or other components are not excluded.

As shown in Figure 1, the high-pressure cold-end EGR system of the engine according to the specific embodiment of the utility model is an effective measure to reduce the generation of NOx gas in the engine cylinder, and it specifically includes: EGR valve 1, EGR cooler 2, EGR mixer (not shown in the figure) and controller. The exhaust gas is drawn from the exhaust pipe in front of the turbine of the supercharger 4, and after returning to the compressor of the supercharger 4, a part of the exhaust gas of the engine is cooled and then sent back to the engine cylinder to participate in the combustion process. The main components of the exhaust gas It is CO2, H2O, N2, etc. Among them, the triatomic gas CO2 and H2O with higher specific heat capacity increase the specific heat capacity of the mixture in the cylinder, reduce the temperature in the cylinder before the ignition of the combustible mixture, and also reduce the temperature of the combustion process; at the same time, After the introduction of EGR, the oxygen content of the mixture in the cylinder decreases, which reduces the combustion rate and heat release rate. This series of effects can effectively reduce the formation of NOx emissions. The high-pressure cold-end EGR system of this engine has relatively few connecting pipes, which does not cause pollution to the intercooler 5 and supercharger 4, and the change of exhaust back pressure does not directly affect the flow of EGR exhaust gas, and the transient response is good . Moreover, the exhaust gas is first cooled by the EGR cooler and then enters the EGR valve, which has lower requirements on the heat resistance of the EGR valve and lower cost; the arrangement of the EGR valve is relatively easy.

Specifically, the EGR cooler 2 is respectively provided with an exhaust gas channel and a coolant channel, and the exhaust gas flowing through the EGR cooler is cooled by introducing engine coolant. The cooling efficiency of the EGR cooler directly affects the mixing temperature of the fresh air entering the engine and the exhaust gas, and a good cooling efficiency can effectively improve the engine performance. The intake end of the exhaust gas channel of the EGR cooler 2 is connected to the exhaust pipe before the turbine of the supercharger 4, and after the exhaust gas is drawn out from the exhaust pipe before the turbine of the supercharger 4, it is cooled to a suitable temperature by heat exchange. After entering the engine temperature.

The inlet end of the EGR valve 1 is connected with the outlet end of the exhaust gas channel of the EGR cooler 2 . By adjusting the opening of the EGR valve, the precise control of the EGR amount of the engine can be realized. According to the requirements of different operating conditions, an appropriate amount of exhaust gas is provided to participate in the combustion process to optimize engine emissions and performance. At present, the main type of EGR valve used by Yuchai is a poppet valve driven by a DC motor, which has a fast response speed. Through the position sensor of the valve body and the air mass flow meter of the vehicle intake system, a two-stage closed-loop can be realized to effectively ensure the operation process of the vehicle. Responsiveness, stability and followability of EGR valve control. The product has good durability and has the functions of self-cleaning, self-learning and flexible seating.

Preferably, the EGR valve 1 is made of cast aluminum.

The exhaust gas inlet of the EGR mixer is connected to the outlet of EGR valve 1, the air inlet of the EGR mixer is connected to the downstream of the intercooler of the engine intake system, and the exhaust gas is drawn out from the exhaust pipe before the turbine of the supercharger 4 And after getting back to the compressor of the supercharger 4, it is mixed with the fresh air through the intercooler and then sent back to the engine cylinder.

Preferably, the EGR cooler 2 is a shell-and-tube cooler or a plate-fin cooler.

Preferably, a check valve 6 is also provided between the EGR cooler 2 and the EGR valve 1 .

The controller is usually integrated in the engine ECU to control a certain amount of exhaust gas drawn from the exhaust pipe in front of the supercharger and cooled by the EGR cooler to be introduced into the combustion chamber; the ECU according to the current engine operating conditions and air The intake demand controls the opening of the EGR valve, and the exhaust gas mixes with the fresh air passing through the intercooler and enters the cylinder to participate in the combustion process. The EGR flow adopts two-level closed-loop control, the first-level closed-loop control is a position closed-loop based on the EGR valve position sensor, and the second-level closed-loop control is a flow closed-loop based on the air mass flow meter, so as to realize the accurate control of the EGR flow in the full range of engine working conditions control.

Preferably, the engine is a gas engine, that is, the high-pressure cold-end EGR system adopting the arrangement of the cold-end EGR valve is preferably suitable for a gas engine.

To sum up, the exhaust gas of the high-pressure cold-end EGR system of this engine is drawn from the exhaust pipe in front of the turbocharger turbine, and the exhaust gas is cooled by the EGR cooler before entering the EGR valve, and there are relatively few connecting pipelines. The intercooler and supercharger do not cause pollution, and the change of exhaust back pressure does not directly affect the EGR exhaust gas flow, and the transient response is good. Moreover, the requirements for the heat resistance of the EGR valve are lower, and the cost is lower; the arrangement of the EGR valve is relatively easy.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various exemplary embodiments of the present invention and various Different options and changes. It is intended that the scope of the invention be defined by the claims and their equivalents.

Claims (6)

1. a kind of high pressure cold end egr system of engine, which is characterized in that including：

Cooler for recycled exhaust gas is inside respectively equipped with exhaust steam passage and cooling passage, the inlet end of the exhaust steam passage and the whirlpool of booster Exhaust pipe connection before wheel is carried out by heat exchange method exhaust gas after being drawn in the exhaust pipe before the turbine of booster cold But；

EGR valve, inlet end are connect with the outlet side of the cooler for recycled exhaust gas exhaust steam passage；

EGR mixer, exhaust gas entrance are connect with the outlet side of the EGR valve, the air intake of EGR mixer and engine into Gas system connects；And

Controller is integrated in Engine ECU, for controlling institute according to the operating condition and air inlet demand of engine State the aperture of EGR valve.

2. the high pressure cold end egr system of engine according to claim 1, which is characterized in that the cooler for recycled exhaust gas is pipe Shell-type cooler or strip-fin oil cooler.

3. the high pressure cold end egr system of engine according to claim 1, which is characterized in that the cooler for recycled exhaust gas with Check valve is additionally provided between EGR valve.

4. the high pressure cold end egr system of engine according to claim 1, which is characterized in that the engine is gas Machine.

5. the high pressure cold end egr system of engine according to claim 1, which is characterized in that the sky of the EGR mixer The charge air cooler downstream of gas entrance and engine aspirating system connects.

6. the high pressure cold end egr system of engine according to claim 1, which is characterized in that the EGR valve uses cast aluminium Material makes.