JP2005147049A - Exhaust gas reflux device for engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas reflux device for an engine with a supercharger capable of performing EGR sufficiently and enlarging an operation region for performing EGR even when intake pressure becomes higher than exhaust pressure in most of operation regions in the supercharging engine. <P>SOLUTION: This exhaust gas reflux device for the engine with the supercharger provided with an EGR passage 7 for leading a part of exhaust gas into an intake passage 6 as EGR gas from an exhaust passage 3 and the supercharger 4 for supercharging intake air is provided with an EGR booster 8 for feeding EGR gas under pressure by utilizing intake pressure in the EGR passage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

    The present invention relates to an exhaust gas recirculation device for a supercharged engine.

  In an engine provided with a supercharger, it is difficult to perform EGR because the supply air pressure is higher than the exhaust pressure in most operating regions.

  As an exhaust gas recirculation device of the prior art, for example, there is one disclosed in Patent Document 1. As shown in FIG. 2, this exhaust gas recirculation apparatus exhausts engine 51, an intake passage 56 that guides intake air to engine 51, an exhaust passage 53 that guides exhaust gas from engine 51, and a part of the exhaust gas as EGR gas. An EGR passage 57 that leads from the passage 53 to the intake passage 56 and a supercharger 54 that supercharges intake air are provided.

  The EGR passage 57 is provided with an exhaust recirculation air supply device 59 that sucks EGR gas from the exhaust passage 53 downstream of the muffler 58 and pressure-feeds it to the intake passage 56 via the exhaust recirculation valve 52. The exhaust gas recirculation gas supply device 59 is driven by the exhaust pressure of the exhaust gas flowing through the exhaust passage 53.

By adopting such a configuration, EGR is going to be performed without hindrance.
Japanese Patent Application Laid-Open No. 07-91325

  However, in the exhaust gas recirculation device using the exhaust gas recirculation device, since the EGR gas is sucked from the most downstream side of the exhaust passage, the EGR pressure is sufficiently high with respect to the supply air pressure even if the pressure is increased by the exhaust gas recirculation gas supply device. In particular, sufficient EGR cannot be performed in a high supercharged engine.

  An object of the present invention is to provide an exhaust gas recirculation device for an engine with a supercharger that solves the above-described problems and can sufficiently perform EGR in a high supercharged engine.

  In order to achieve the above object, a first aspect of the present invention is a supercharger comprising: an EGR passage that leads a part of exhaust gas from the exhaust passage to the intake passage as EGR gas; and a supercharger that supercharges intake air. In the exhaust gas recirculation apparatus for an attached engine, an EGR booster that pumps EGR gas using intake pressure is provided in the EGR passage.

  According to a second invention, in the first invention, a variable throttle valve for controlling a flow rate of EGR gas led to the EGR passage is provided on the exhaust passage downstream of the branch portion of the exhaust passage and the EGR passage.

  According to a third aspect, in the first aspect, a venturi that draws EGR gas is provided in the intake passage, and the EGR passage communicates with the venturi.

  In a fourth aspect based on the first aspect, an EGR cooler that cools EGR gas is provided in the EGR passage.

  In a fifth aspect based on the first aspect, an intake air cooler for cooling intake air is provided in the intake passage.

  According to a first aspect of the present invention, in an exhaust gas recirculation device for a supercharged engine, comprising: an EGR passage that guides a part of exhaust gas from the exhaust passage to the intake passage as EGR gas; and a supercharger that supercharges intake air. By providing an EGR booster that pumps EGR gas using intake pressure in the EGR passage, sufficient EGR can be performed even in a highly supercharged engine in which the supply pressure is higher than the exhaust pressure in most operating regions And the operating range in which EGR can be performed can be expanded.

  According to the second invention, the variable throttle valve for controlling the flow rate of the EGR gas led to the EGR passage is provided on the exhaust passage downstream of the branch portion of the exhaust passage and the EGR passage. It is possible to adjust to an appropriate EGR rate.

  According to the third aspect of the present invention, the vent passage for drawing EGR gas is provided in the intake passage, and the EGR passage communicated with the venturi allows the EGR gas pumped from the EGR booster to be drawn into the flow of intake air. it can. Thus, by performing EGR using both the EGR booster's pumping force and the venturi's suction force, sufficient EGR is performed even in a highly supercharged engine in which the supply pressure is higher than the exhaust pressure in most operating regions. It is possible to expand the operating range in which EGR can be performed.

  According to the fourth invention, the EGR gas can be cooled by providing an EGR cooler for cooling the EGR gas in the EGR passage.

  According to the fifth invention, the intake air can be cooled by providing the intake air cooler for cooling the intake air in the intake passage.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an exhaust gas recirculation apparatus of this embodiment.

  The engine 1 is a six-cylinder engine having six cylinders, and includes an intake passage 6 that guides intake air to each cylinder and an exhaust passage 3 that guides exhaust gas from each cylinder.

  The exhaust passage 3 is provided with a muffler 22 that silences the exhaust sound.

  The intake passage 6 is provided with a supercharger 4 that supercharges intake air using the driving force of the engine 1.

  An intake air cooler 60 is provided downstream of the supercharger 4 in the intake passage 6 to cool the intake air that has been supercharged by the supercharger and heated to a high temperature.

  The intake passage 6 and the exhaust passage 3 are communicated by an EGR passage 7, and a part of the exhaust gas is recirculated from the exhaust passage 3 to the intake passage 6 as EGR gas.

  A venturi 9 is provided at the communication portion between the intake passage 6 and the exhaust passage 3. The venturi 9 throttles the intake passage 6 to increase the flow velocity of the intake air, and causes the EGR gas to be drawn into the intake air flow by the ejector effect.

  The EGR passage 7 is provided with an EGR cooler 11 that lowers the temperature of the EGR gas. The EGR cooler 11 recirculates more EGR gas by lowering the temperature of the EGR gas and increasing the density of the EGR gas.

  The EGR passage 7 includes a turbine 8a and a compressor 8b, and is provided with an EGR booster 8 that increases EGR gas using intake air pressure.

  The turbine 8 a of the EGR booster 8 is disposed on the intake passage 6 between the supercharger 4 and the venturi 9. The compressor 8 b of the EGR booster 8 is disposed on the EGR passage 7 downstream of the EGR cooler 11.

  The turbine 8a rotates using the intake air pressurized by the supercharger 4, and transmits the rotational force to the compressor 8b via a shaft directly connected on the same axis. The compressor 8 b increases the pressure of EGR gas and pumps it to the venturi 9. Since the EGR booster 8 is driven by high-pressure intake air from the supercharger 4, no external power source such as an electric motor or a hydraulic motor is required.

  A variable throttle valve 19 for controlling the flow rate of exhaust gas is provided on the exhaust passage 3 downstream of the branch portion between the EGR passage 7 and the exhaust passage 3. The variable throttle valve 19 is configured to change the opening degree by rotating the valve body by an actuator. The controller 20 which is a control means controls the flow rate of the EGR gas guided to the EGR passage 7 by restricting or opening the exhaust passage 3 by controlling the opening degree of the variable throttle valve 19. That is, when the variable throttle valve 19 is throttled, the flow rate of EGR gas guided to the EGR passage 7 increases. Thereby, the EGR rate can be controlled.

  Here, the effect of this embodiment is demonstrated.

  Exhaust gas discharged from the engine 1 is discharged through the exhaust passage 3. The controller 20 guides a part of the exhaust gas as EGR gas to the EGR passage 7 by restricting or opening the exhaust passage 6 by the variable throttle valve 19 according to the operating state of the engine. After the EGR gas is cooled by the EGR cooler 11, the pressure is increased by the EGR booster 8 and is pumped to the venturi 9. The EGR gas is drawn into the flow of intake air in the venturi 9 and mixed with the intake air.

  As described above, by performing EGR using both the pumping force of the EGR booster 8 and the suction force of the venturi 9, the supercharged supercharged engine 1 in which the supply air pressure becomes higher than the exhaust pressure in almost all operation regions. In this case, sufficient EGR can be performed, and the operating range in which EGR can be performed can be expanded.

  In the present embodiment, the variable throttle valve 19 is provided on the exhaust passage 3, but the present invention is not limited to this. For example, the variable throttle valve 19 may be provided on the EGR passage 7 to control the EGR rate.

  Further, instead of providing the variable throttle valve 19, the turbine 8a of the EGR booster 8 may be configured to change its angle by rotating the nozzle blade, and the EGR rate may be controlled by controlling the angle of the variable nozzle.

  Although the present invention has been described in certain terms with regard to structural and methodological features, the means disclosed herein include preferred forms of practicing the invention, and the invention is illustrated and described. It should be understood that the invention is not limited to specific features. Accordingly, the present invention includes any forms or modifications within the scope of the claims as appropriately interpreted in accordance with the principle of equality.

  The present invention can be applied to an exhaust gas recirculation device for a supercharged engine.

It is a block diagram which shows the exhaust gas recirculation apparatus of 1st Embodiment. It is a block diagram which shows the exhaust-gas recirculation apparatus of a prior art.

Explanation of symbols

1 Engine 3 Exhaust passage 4 Supercharger 6 Intake passage 7 EGR passage 8 EGR booster 9 Venturi 11 EGR cooler 19 Variable throttle valve 20 Controller 22 Muffler

Claims (5)

  In an exhaust gas recirculation device for a supercharged engine having an EGR passage for leading a part of exhaust gas from an exhaust passage to the intake passage as EGR gas and a supercharger for supercharging intake air, an intake pressure is applied to the EGR passage. An exhaust gas recirculation device for an engine with a supercharger, characterized in that an EGR booster that pumps EGR gas by using an EGR gas is provided.   The supercharger according to claim 1, wherein a variable throttle valve for controlling a flow rate of EGR gas led to the EGR passage is provided on the exhaust passage downstream of the branch portion of the exhaust passage and the EGR passage. Engine exhaust gas recirculation device.   The exhaust gas recirculation device for a supercharged engine according to claim 1, wherein a venturi for drawing EGR gas is provided in the intake passage, and the EGR passage is communicated with the venturi.   The exhaust gas recirculation apparatus for an engine with a supercharger according to claim 1, wherein an EGR cooler for cooling EGR gas is provided in the EGR passage.   The exhaust gas recirculation apparatus for a supercharged engine according to claim 1, wherein an intake air cooler for cooling intake air is provided in the intake passage.

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