CN107939558B - An internal combustion engine exhaust system with exhaust gas recirculation - Google Patents

Abstract

The invention discloses an internal combustion engine exhaust system with exhaust gas recirculation, including a plurality of engine cylinders, exhaust manifolds, EGR valves, EGR coolers, intake manifolds, turbines, supercharger compressors, supercharger Air cooler and intercooling rear intake pipe; it is characterized in that: a plurality of said engine cylinders are grouped and respectively connected with a plurality of said exhaust manifolds; said turbine has a plurality of turbine volute chambers leading to the turbine impeller; a plurality of said Exhaust manifolds respectively enter the corresponding plurality of turbine volute chambers; at least part of the exhaust manifolds are simultaneously connected with the EGR valve. The beneficial effect of the invention is that the three-channel supercharger volute and the exhaust manifold arrangement are more conducive to reducing the interference between the exhaust of each cylinder, and the exhaust pulse effect is used to facilitate the maintenance of exhaust energy. The beneficial effect of the present invention is that the volute chambers of different cross-sectional areas are arranged in the volute of the three-channel supercharger, which can form the asymmetry of the volute with different gradients, and facilitate the optimization of the EGR rate under different working conditions of the engine.

Description

An internal combustion engine exhaust system with exhaust gas recirculation

technical field

The invention belongs to the technical field of turbocharged internal combustion engines, in particular to an exhaust system of an internal combustion engine with exhaust gas recirculation using an asymmetrical turbocharger.

Background technique

In order to meet the engine emission requirements, the engine is provided with the proper EGR rate through the asymmetric turbocharger, EGR valve and related exhaust system.

The currently existing solution is mainly disclosed in the patent CN104508284 (A), that is, through the asymmetric dual-channel supercharger and the EGR valve, the EGR rate requirements under different working conditions of the engine are met by controlling the EGR valve. Its disadvantage is that when the asymmetry of the turbine volute is large, it is difficult to generate a large exhaust gas pressure, and the EGR rate requirement can only be met through a forced EGR valve. When the asymmetry is small, at high speed and heavy load, the exhaust back pressure is high, and an excessive EGR rate will be generated. Daimler tends to adopt a larger asymmetry and meet the EGR rate requirements by forcing the EGR valve in some working conditions.

The main disadvantages of this solution are: 1) The three cylinders share one volute exhaust flow channel, which causes more exhaust energy dissipation among the cylinders. 2) The forced EGR valve is directly subjected to high-temperature exhaust scour, which brings high thermal load and poor reliability. In addition, the forced EGR valve also brings exhaust energy loss.

Contents of the invention

The purpose of the present invention is to provide a turbocharger and an internal combustion engine exhaust system with exhaust gas recirculation using an asymmetrical turbocharger, which can improve the exhaust energy utilization of the turbocharger as much as possible while satisfying the EGR rate of the engine Rate.

In order to achieve the above object, the present invention adopts the following technical solutions:

An internal combustion engine exhaust system with exhaust gas recirculation, including multiple engine cylinders, exhaust manifold, EGR valve, EGR cooler, intake manifold, turbine, supercharger compressor, charge intercooler and intercooler Intake pipe after cooling; the exhaust gas of the engine cylinder partly enters the turbine through the exhaust manifold, and partly enters the engine cylinder again through the EGR valve, EGR cooler and intake manifold; the intake air of the engine cylinder The gas returns to the engine cylinder after passing through the supercharger compressor, the supercharged intercooler and the intercooled intake pipe, and it is characterized in that: a plurality of the engine cylinders are grouped and respectively connected to a plurality of the exhaust manifolds; The turbine has a plurality of turbine volute chambers leading to the turbine wheel; a plurality of exhaust manifolds respectively enter the corresponding plurality of turbine volute chambers; at least part of the exhaust manifolds are simultaneously connected with the EGR valve connected.

It is further characterized in that: each of the exhaust manifolds is at least connected to the exhaust gas of two engine cylinders.

Preferably: the number of cylinders of the engine is six, and the two-by-two combination is connected with three exhaust manifolds, and the turbine includes a first turbine volute cavity, a second turbine volute cavity, and a third turbine volute cavity; The first exhaust manifold in the exhaust manifold is simultaneously connected to the EGR valve and the first turbine volute cavity, and the second exhaust manifold is simultaneously connected to the EGR valve and the second turbine volute cavity, The third exhaust manifold is separately connected with the third turbine volute cavity.

The cross-sectional areas of the first turbine volute cavity, the second turbine volute cavity and the third turbine volute cavity are arranged in gradients.

Preferably: the cross-sectional area of the third turbine volute cavity is larger than that of the second turbine volute cavity and the first turbine volute cavity.

The sections of the second turbine volute cavity and the third turbine volute cavity are arranged asymmetrically.

The EGR valve is a three-way valve.

The beneficial effect of the invention is that the arrangement of the volute of the three-channel supercharger and the exhaust manifold is more conducive to reducing the interference between the exhaust of each cylinder, and the use of the exhaust pulse effect facilitates the maintenance of exhaust energy. The beneficial effect of the present invention is that the volute chambers of different cross-sectional areas are arranged in the volute of the three-channel supercharger, which can form the asymmetry of the volute with different gradients, and facilitate the optimization of the EGR rate under different working conditions of the engine.

Description of drawings

Figure 1 is a schematic diagram of the engine system architecture of the present invention.

Fig. 2 is a schematic diagram of the structure of a turbine volute cavity of the turbine of the present invention.

Fig. 3 is a schematic diagram of the structure of the second turbine volute cavity of the present invention.

Fig. 4 is a schematic diagram of the structure of the third turbine volute cavity of the present invention.

Figure 5-9 is a schematic diagram of the state of the EGR valve under different working conditions.

Detailed ways

As shown in Figure 1, an internal combustion engine exhaust system with exhaust gas recirculation using an asymmetric turbocharger includes a plurality of engine cylinders, an exhaust manifold, an EGR valve 20, an EGR cooler 19, and a pipeline after EGR cooling 18. Intake manifold 17, turbine, supercharger compressor 28, supercharged intercooler 29 and intercooled rear intake pipe 30; the exhaust gas from the engine cylinder enters the turbine partly through the exhaust manifold, partly through the EGR valve 20, The EGR cooler 19, intake manifold 17 again enters the engine cylinders. The gas discharged from the first cylinder 11 and the second cylinder 12 of the engine cylinder is introduced into the first exhaust manifold 21; the gas discharged from the third cylinder 13 and the fourth cylinder 14 is introduced into the second exhaust manifold 22; the fifth cylinder 15 and Gas exhausted from the sixth cylinder 16 is introduced into the third exhaust manifold 23 . Gases flowing out of the second exhaust manifold 22 and the third exhaust manifold 23 are at least partially recirculated to the intake manifold 17 . The gas in the first exhaust manifold 21, the second exhaust manifold 22 and the third exhaust manifold 23 are sent to the first turbine volute cavity 24, the second turbine volute cavity 25 and the third turbine volute cavity of the turbine respectively. In the turbine volute cavity 26, the turbine impeller 27 is pushed.

As shown in FIG. 2 , the above-mentioned asymmetric turbocharger includes a turbine, and the turbine includes a volute and a turbine blade 31 . Three volute chambers are arranged in the turbine volute, a first turbine volute chamber 24 , a second turbine volute chamber 25 , and a third turbine volute chamber 26 . The three volute chambers are respectively connected with three different sets of exhaust manifolds. The third turbine volute cavity 26 has a larger cross-sectional area than the second turbine volute cavity 25 and the first turbine volute cavity 24 . Part of the gas entering the first exhaust manifold 21 and the second exhaust manifold 22 is recirculated through EGR, and the remaining part enters the first turbine volute cavity 24 and the second turbine volute cavity 25 of the turbine respectively. Compared with the prior art, the present invention sets the volute cavity 25 and the volute cavity 24 with different degrees of asymmetry relative to the volute cavity 26 . The set asymmetric flow channel is more conducive to the formation of EGR rates with different gradients, which facilitates the optimization of EGR rates under different engine operating conditions.

Through the structure shown in Fig. 2, the following effects can be produced. The three sets of exhaust manifolds of the engine are respectively connected with the first turbine volute cavity 24 , the second turbine volute cavity 25 and the third turbine volute cavity 26 . It enters the turbine through the volute cavity and expands to do work. Since the first turbine volute cavity 24 , the second turbine volute cavity 25 and the third turbine volute cavity 26 have different throat areas, the airflows in the three groups of volute cavities are throttled to different degrees. The throttling of the air flow in the third turbine volute cavity 26 is relatively small, so the energy of the gas in the third turbine volute cavity 26 is well maintained, and the gas pressure is low, which can ensure a higher working efficiency of the turbine. The throat areas of the first turbine volute cavity 24 , the second turbine volute cavity 25 , and the third turbine volute cavity 26 increase sequentially. Under the influence of throttling, the pressures of the first turbine volute cavity 24 , the second turbine volute cavity 25 and the third turbine volute cavity 26 decrease sequentially. The first turbine volute cavity 24 and the second turbine volute cavity 25 have higher pressure than the third turbine volute cavity 26 , so they can form an appropriate pressure gradient relative to the pressurized intake air. This facilitates use of the hot end EGR valve to provide the EGR rate required by the engine. Further, the first turbine volute cavity 24 has a smaller throat area than the second turbine volute cavity 25 , so it can form a larger pressure gradient relative to the boosted intake air. It is convenient to provide a smaller amount of exhaust gas recirculation at low engine speeds. When the engine needs a large amount of EGR, the first exhaust manifold 21 and the second exhaust manifold 22 can be partially exhausted through the EGR pipeline, and the first turbine volute cavity 24 and the second turbine volute can be used to The pressure difference formed by the shell cavity 25 is introduced into the EGR cooler at the same time.

Figure 5-9 is a schematic diagram of the state of the EGR valve under different working conditions.

When the engine is running at low speed and high load, the engine needs a lower EGR rate, as shown in Figure 9, at this time, the EGR valve plate 36 closes the second flow passage 35, the first flow passage 34 is opened, and EGR enters through the EGR cooler 19 Intake manifold 17. When the engine is running at low speed and low load, a higher EGR rate is required, and the EGR valve plate 36 partially opens or fully opens the second flow passage 35 and the first flow passage 34, as shown in FIGS. 6 and 7 . When the engine requires a moderate EGR rate, the EGR valve plate 36 partially opens the second flow passage 35 , or the EGR valve plate 36 closes the first flow passage 34 , as shown in FIGS. 5 and 8 .

In the present invention, it is also possible to set the second volute cavity 25 to be smaller than the first turbine volute cavity 24, as shown in FIG. 3 . Or as shown in FIG. 4 , the asymmetric turbocharger includes a turbine, and the turbine includes a volute and a turbine blade 31 . Three volute chambers are arranged in the turbine volute, a first turbine volute chamber 24 , a second turbine volute chamber 25 , and a third turbine volute chamber 26 . The three volute chambers are respectively connected with three different sets of exhaust manifolds. The second volute cavity 25 of the turbine volute has a larger cross-sectional area than the first turbine volute cavity 24 and the third turbine volute cavity 26 . Part of the gas entering the first exhaust manifold 21 and the second exhaust manifold 22 is recirculated through EGR, and the remaining part enters the first turbine volute cavity 24 and the third turbine volute cavity 26 of the turbine respectively.

The present invention has been described above, and it is obvious that the specific implementation of the present invention is not limited by the above-mentioned mode, as long as various insubstantial improvements are adopted in the method concept and technical scheme of the present invention, or the concept of the present invention is not improved. And technical solutions that are directly applied to other occasions are within the protection scope of the present invention.

Claims (5)

1. An internal combustion engine exhaust system with exhaust gas recirculation comprises a plurality of engine cylinders, an exhaust manifold, an EGR valve, an EGR cooler, an air inlet manifold, a turbine, a supercharger compressor, a supercharged intercooler and an intermediate-cold rear air inlet pipe; the exhaust gas of the engine cylinder partially enters the turbine through the exhaust manifold, and partially reenters the engine cylinder through the EGR valve, the EGR cooler and the intake manifold; the method is characterized in that: a plurality of engine cylinders are connected with a plurality of exhaust manifolds in groups respectively; the turbine has a plurality of turbine volute chambers opening into a turbine wheel; a plurality of said exhaust manifolds respectively entering a corresponding plurality of said turbine volute chambers; at least part of the exhaust manifold is simultaneously connected with the EGR valve;

each exhaust manifold is connected with at least two engine cylinder exhausts;

the number of the engine cylinders is six, every two engine cylinders are combined and connected with three exhaust manifolds, and the turbine comprises a first turbine volute cavity, a second turbine volute cavity and a third turbine volute cavity; and a first exhaust manifold of the three exhaust manifolds is simultaneously connected with the EGR valve and the first turbine volute cavity, a second exhaust manifold is simultaneously connected with the EGR valve and the second turbine volute cavity, and a third exhaust manifold is separately connected with the third turbine volute cavity.

2. An internal combustion engine exhaust system with exhaust gas recirculation according to claim 1, characterized in that: the sectional areas of the first turbine volute cavity, the second turbine volute cavity and the third turbine volute cavity are arranged in a gradient manner.

3. An internal combustion engine exhaust system with exhaust gas recirculation according to claim 2, characterized in that: the sectional area of the third turbine volute cavity is larger than that of the second turbine volute cavity and the first turbine volute cavity.

4. An internal combustion engine exhaust system with exhaust gas recirculation according to claim 3, characterized in that: the second turbine volute cavity and the third turbine volute cavity are asymmetrically arranged in cross section.

5. An internal combustion engine exhaust system with exhaust gas recirculation according to any one of claims 1 to 4, characterized in that: the EGR valve is a three-way valve.