JP2005171961A - Exhaust reflux device of supercharged engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely conduct recirculation of exhaust gas, even under a highly supercharged condition by supercharger of the exhaust reflux device of a supercharged engine which is suitable for an engine provided with a supercharger which pressurizes air, and supplies it to the inlet manifold of the engine. <P>SOLUTION: The exhaust reflux device of the supercharged engine recirculates exhaust from the engine to the inlet manifold of the engine provided with the supercharger which pressurizes the air and supplies it to the inlet manifold of the engine. The exhaust reflux device is provided with an exhaust reflux passage, connecting the exhaust manifold of the engine to the inlet manifold, an EGR booster and an outside air booster. The EGR booster is provided with an EGR compressor, arranged at the exhaust reflux passage, for pressurizing the exhaust from the exhaust manifold and an air turbine for driving the compressor. Then the outside air booster is provided with an air compressor which supplies pressurized air to the air turbine, and an exhaust turbine which drives the air compressor by the exhaust from the exhaust manifold. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust gas recirculation device that recirculates exhaust gas from an engine to an intake manifold, and particularly to an exhaust gas recirculation system of a supercharged engine suitable for an engine having a supercharger that pressurizes and supplies air to the intake manifold of the engine. Relates to the device.

Conventionally, exhaust gas recirculation (EGR) is known in which exhaust gas from an engine is recirculated to an intake manifold to lower the combustion temperature and suppress generation of NOx.
Further, a turbocharger is used to pressurize air and supply it to an intake manifold of the engine to increase the output of the engine.

Conventionally, an exhaust gas recirculation device for a supercharged engine in which exhaust gas recirculation is applied to an engine equipped with a turbocharger is disclosed in JP-A-7-91325.
In the exhaust gas recirculation device for a supercharged engine in this publication, the exhaust on the downstream side of the silencer is recirculated to the engine via an exhaust gas recirculation device driven by the exhaust of the engine. Can be supplied to the engine.
JP-A-7-91325

However, in the exhaust gas recirculation device of the supercharged engine disclosed in the above-mentioned publication, the exhaust gas having a low pressure downstream of the silencer is supplied to the engine via an exhaust gas recirculation air supply device driven by the exhaust gas of the engine. Due to the recirculation, there is a problem that it may be difficult to reliably perform exhaust gas recirculation.
In particular, in an engine equipped with a supercharger, it is difficult to reliably perform exhaust gas recirculation because the supply air pressure is higher than the exhaust pressure in most operating regions.

  The present invention has been made to solve such a conventional problem, and provides an exhaust gas recirculation device for a supercharged engine that can reliably perform exhaust gas recirculation even under high supercharging by a supercharger. Objective.

  An exhaust gas recirculation device for a supercharged engine according to claim 1 is provided for a supercharged engine that recirculates exhaust gas from the engine to the intake manifold of the engine having a supercharger that pressurizes and supplies air to the intake manifold of the engine. In the exhaust gas recirculation device, an exhaust gas recirculation passage that communicates an exhaust manifold of the engine to the intake manifold, an EGR compressor that is disposed in the exhaust gas recirculation passage and pressurizes exhaust gas from the exhaust manifold, and an air turbine that drives the EGR compressor And an outside air booster having an air compressor for supplying pressurized air to the air turbine and an exhaust turbine for driving the air compressor by exhaust from the exhaust manifold.

  The exhaust gas recirculation device for a supercharged engine according to claim 2 is the exhaust gas recirculation device for a supercharged engine according to claim 1, wherein the exhaust gas recirculation passage is an exhaust passage in which the exhaust turbine is disposed and exhausts exhaust gas from the exhaust manifold. The supercharger is arranged and connected to the downstream side of the supercharger of the intake passage for leading the pressurized air from the supercharger to the intake manifold, and upstream of the EGR booster of the exhaust recirculation passage An inlet side check valve for preventing the backflow of exhaust gas to the exhaust passage side is disposed, and an outlet side check valve for blocking the inflow of intake air from the intake passage is provided downstream of the EGR booster in the exhaust gas recirculation passage. It is arranged.

  The exhaust gas recirculation device for a supercharged engine according to claim 3 is the exhaust gas recirculation device for a supercharged engine according to claim 1 or 2, wherein the exhaust gas recirculation passage is provided with the exhaust turbine and exhausts the exhaust gas from the exhaust manifold. Branching from the exhaust passage to be exhausted, the supercharger is arranged and connected to the downstream side of the supercharger of the intake passage for leading the pressurized air from the supercharger to the intake manifold. An EGR tank that temporarily stores water is disposed.

The exhaust gas recirculation device for a supercharged engine according to claim 4 is the exhaust gas recirculation device for a supercharged engine according to claim 3, wherein the EGR tanks are arranged on the downstream side and the upstream side of the EGR booster in the exhaust gas recirculation passage. It is characterized by becoming.
The exhaust gas recirculation device for a supercharged engine according to claim 5 is the exhaust gas recirculation device for a supercharged engine according to any one of claims 1 to 4, wherein the supercharger is disposed in the exhaust gas recirculation passage. An intake throttle portion that is connected to the downstream side of the supercharger of the intake passage that guides pressurized air from the charger to the intake manifold, and that is connected between the downstream side of the supercharger of the intake passage and the connection portion of the exhaust gas recirculation passage It is characterized by arranging.

(Function)
In the exhaust gas recirculation device for the supercharged engine according to the first aspect, air is pressurized by the supercharger and supplied to the intake manifold of the engine. Then, relatively high-pressure exhaust gas from the exhaust manifold of the engine flows into the exhaust gas recirculation passage, is pressurized by the EGR booster driven by pressurized air from the outside air booster, and is then guided to the intake manifold.

  In the outside air booster, external air is pressurized by driving an air compressor by an exhaust turbine. In the EGR booster, exhaust gas is pressurized by driving an EGR compressor by an air turbine. A turbocharger can be used. As an EGR booster, the same material as that of a conventional turbocharger compressor can be used for an air turbine, and the same material as that of a conventional turbine can be used for an EGR compressor.

In the exhaust gas recirculation device for the supercharged engine according to claim 2, the backflow of the exhaust gas to the exhaust passage side is prevented by the inlet side check valve disposed upstream of the EGR booster in the exhaust gas recirculation passage. The outlet check valve arranged downstream prevents the intake air from flowing in from the intake passage.
In the exhaust gas recirculation device for the supercharged engine according to claim 3, since the EGR tank is disposed in the exhaust gas recirculation passage and the exhaust gas is temporarily stored, even if the exhaust period and the intake period do not overlap as in the single cylinder engine, Reflux is performed smoothly.

In the exhaust gas recirculation device for the supercharged engine according to the fourth aspect, the EGR tanks are arranged on the downstream side and the upstream side of the EGR booster in the exhaust gas recirculation passage, thereby preventing the EGR compressor from surging.
In the exhaust gas recirculation device for the supercharged engine according to claim 5, the intake throttle portion is disposed between the downstream side of the supercharger of the intake passage and the connection portion of the exhaust recirculation passage, whereby the pressure on the intake manifold side of the intake passage is reduced. During the intake period, the pressure drops like a pulse, and the exhaust gas from the exhaust gas recirculation passage easily flows into the intake passage in a pulsed manner.

In the exhaust gas recirculation device for a supercharged engine according to claim 1, after relatively high pressure exhaust gas from the exhaust manifold of the engine flows into the exhaust gas recirculation passage and is pressurized by the EGR booster driven by pressurized air from the outside air booster. Since the exhaust gas is guided to the intake manifold, exhaust gas recirculation can be reliably performed even under high supercharging by the supercharger.
In the outside air booster, external air is pressurized by driving an air compressor with an exhaust turbine. In the EGR booster, exhaust gas is pressurized by driving an EGR compressor with an air turbine. Moreover, the air turbine side of the EGR booster is prevented from becoming hot, and a commercially available turbocharger can be used for the outside air booster and the EGR booster.

In the exhaust gas recirculation device for a supercharged engine according to claim 2, an inlet side check valve for preventing a reverse flow of exhaust gas to the exhaust passage side is disposed upstream of the EGR booster in the exhaust gas recirculation passage, and downstream of the EGR booster in the exhaust gas recirculation passage. Since the outlet side check valve for blocking the inflow of intake air from the intake passage is disposed in the exhaust passage, exhaust gas recirculation can be performed more reliably even under high supercharging by the supercharger.
In the exhaust gas recirculation device for the supercharged engine according to the third aspect, the EGR tank for temporarily storing the exhaust gas is disposed in the exhaust gas recirculation passage. Therefore, even in an engine having a small number of cylinders, the exhaust gas can be stably and reliably supplied to the intake manifold. it can.

In the exhaust gas recirculation device for the supercharged engine according to the fourth aspect, since the EGR tanks are arranged on the downstream side and the upstream side of the EGR booster in the exhaust gas recirculation passage, surging of the EGR compressor can be effectively prevented.
In the exhaust gas recirculation device for a supercharged engine according to claim 5, since the intake throttle portion is disposed between the downstream side of the supercharger of the intake passage and the connection portion of the exhaust recirculation passage, the pressure on the intake manifold side of the intake passage is changed to a pulse. As a result, the exhaust gas from the exhaust gas recirculation passage tends to flow into the intake passage in a pulsed manner, so that the exhaust gas from the exhaust gas recirculation passage can surely flow into the intake air passage.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows an embodiment of an exhaust gas recirculation device for a supercharged engine according to the present invention. In this embodiment, the present invention is applied to a diesel engine for power generation.
In FIG. 1, the code | symbol 11 has shown the engine which consists of a diesel engine.
The engine 11 includes an intake manifold 13 that performs intake to the engine 11 and an exhaust manifold 15 that discharges exhaust from the engine 11. A crankshaft gear 17 and a transmission 19 are also provided.

An intake passage 21 for supplying air to the intake manifold 13 is opened in the intake manifold 13 of the engine 11.
In this intake passage 21, a supercharger 23, an air tank 25, and an intake throttle valve 27 as an intake throttle portion are interposed in order from the upstream side.
The supercharger 23 is composed of an air compressor and is driven by an electric motor (not shown). Then, intake air from outside is sucked through a filter (not shown) and pressurized to a relatively high pressure.

The air tank 25 temporarily stores the intake air pressurized by the supercharger 23.
The intake throttle valve 27 throttles the intake air from the air tank 25 and temporarily reduces the downstream pressure in a pulsed manner during the intake period. In this embodiment, the intake throttle valve 27 is a variable throttle valve capable of adjusting the throttle amount. However, a venturi (ejector) may be provided instead of the intake throttle valve 27 to serve as a connection part of the exhaust gas recirculation passage.

An exhaust passage 29 is connected to the exhaust manifold 15 of the engine 11. An exhaust turbine 33 and a silencer 35 for the outside air booster 31 are disposed in the exhaust passage 29.
A variable exhaust throttle valve 37 is disposed between the exhaust turbine 33 and the silencer 35 in the exhaust passage 29. Further, a bypass passage 39 is disposed so as to bypass the exhaust turbine 33. A variable throttle valve 41 is disposed in the bypass passage 39 so that the variable throttle valve 41 is opened during operation to reduce exhaust gas recirculation.

In this embodiment, an exhaust gas recirculation passage 43 that communicates the exhaust manifold 15 of the engine 11 with the intake manifold 13 is disposed.
The exhaust gas recirculation passage 43 branches from the exhaust passage 29 upstream of the exhaust turbine 33 and is connected to the intake passage 21 downstream of the intake throttle valve 27.
In the exhaust gas recirculation passage 43, in order from the inlet side, an inlet side check valve 45, a first EGR tank 47, an EGR compressor 51 of an EGR booster 49, an EGR cooler 53, an EGR throttle valve 55, a second EGR tank 57, An outlet check valve 59 is disposed.

The inlet-side check valve 45 prevents the exhaust gas from flowing backward from the exhaust gas recirculation passage 43 to the exhaust passage 29 side. Further, the outlet-side check valve 59 prevents inflow of intake air from the intake passage 21.
The first EGR tank 47 and the second EGR tank 57 temporarily store the exhaust.
The EGR cooler 53 cools the exhaust gas pressurized by the EGR compressor 51. Cooling water such as tap water is supplied to the EGR cooler 53 via the variable throttle valve 61.

The EGR throttle valve 55 throttles the exhaust and guides it to the second EGR tank 57.
The EGR compressor 51 of the EGR booster 49 pressurizes the exhaust from the exhaust manifold 15.
The EGR compressor 51 is driven by the air turbine 63 of the EGR booster 49.

The air turbine 63 is driven by the air pressurized by the air compressor 65 of the outside air booster 31. The air that has driven the air turbine 63 is discharged to the outside through the silencer 65.
On the other hand, the air compressor 65 of the outside air booster 31 is driven by the exhaust turbine 33 of the outside air booster 31. External air is supplied to the air compressor 65 via an air cleaner 67.

  In the above-described exhaust gas recirculation device for the supercharged engine, air is pressurized by the supercharger 23 and supplied to the intake manifold 13 of the engine 11. Then, a relatively high pressure exhaust gas from the exhaust manifold 15 of the engine 11 flows into the exhaust gas recirculation passage 43 and is pressurized by the EGR compressor 51 of the EGR booster 49 driven by the pressurized air from the air compressor 65 of the outside air booster 31. Then, it is guided to the intake manifold 13.

In the outside air booster 31, external air is pressurized by driving the air compressor 65 by the exhaust turbine 33, and in the EGR booster 49, exhaust gas is pressurized by driving the EGR compressor 51 by the air turbine.
In the above-described exhaust gas recirculation device for a supercharged engine, relatively high-pressure exhaust gas from the exhaust manifold 15 of the engine 11 flows into the exhaust gas recirculation passage 43 and is added by an EGR booster 49 driven by pressurized air from the outside air booster 31. After being pressurized, the exhaust gas is guided to the intake manifold 13, so that exhaust gas recirculation can be reliably performed even under high supercharging by the supercharger 23.

  Further, the external air booster 31 pressurizes the external air by driving the air compressor 65 by the exhaust turbine 33, and the EGR booster 49 pressurizes the exhaust gas by driving the EGR compressor 51 by the air turbine 63. The compressor 65 of the outside air booster 31 and the turbine 63 of the EGR booster 49 are prevented from becoming high temperature, and a commercially available turbocharger can be used for the outside air booster 31 and the EGR booster 49.

  In the above-described exhaust gas recirculation device for the supercharged engine, the inlet side check valve 45 that prevents the reverse flow of the exhaust gas to the exhaust passage 29 side is disposed upstream of the EGR booster 49 in the exhaust gas recirculation passage 43. Since the outlet check valve 59 for blocking the inflow of intake air from the intake passage 21 is arranged downstream of the EGR booster 49, exhaust gas recirculation can be performed more reliably even under high supercharging by the supercharger 23. it can.

In the above-described exhaust gas recirculation device for the supercharged engine, since the EGR tanks 47 and 57 for temporarily storing the exhaust gas are disposed in the exhaust gas recirculation passage 43, the exhaust gas can be stably and reliably supplied to the intake manifold 13. .
Furthermore, in the above-described supercharged engine exhaust gas recirculation device, the EGR tanks 47 and 57 are disposed on the downstream side and upstream side of the EGR booster 49 in the exhaust gas recirculation passage 43, so that surging of the EGR compressor 51 is effectively prevented. be able to.

  In the above-described exhaust gas recirculation device for the supercharged engine, the intake throttle valve 27 is disposed between the downstream side of the supercharger 23 of the intake passage 21 and the connection portion of the exhaust gas recirculation passage 43. The pressure on the 13th side decreases in a pulse shape, and the exhaust gas from the exhaust gas recirculation passage 43 is likely to flow into the intake passage 21 in a pulsed manner, so that the exhaust gas from the exhaust gas recirculation passage 43 flows into the intake air passage 21 reliably. Can do.

  In the above-described embodiment, the example in which the present invention is applied to the engine 11 including a diesel engine has been described. However, the present invention is not limited to such an embodiment, and may be applied to, for example, a gasoline engine. it can.

It is explanatory drawing which shows one Embodiment of the exhaust gas recirculation apparatus of the supercharged engine of this invention.

Explanation of symbols

11 Engine 13 Intake manifold 15 Exhaust manifold 21 Intake passage 23 Supercharger 25 Air tank 27 Intake throttle valve 29 Exhaust passage 31 Outside air booster 33 Exhaust turbine 35 Silencer 37 Variable throttle valve 39 Bypass passage 41 Variable throttle valve 43 Exhaust recirculation passage 45 Inlet side Check valve 47 First EGR tank 49 EGR booster 51 EGR compressor 53 EGR cooler 55 EGR throttle valve 57 Second EGR tank 59 Outlet check valve 63 Air turbine 65 Air compressor

Claims (5)

In an exhaust gas recirculation device for a supercharged engine that recirculates exhaust gas from the engine to the intake manifold of the engine having a supercharger that pressurizes air and supplies the air to the intake manifold of the engine.
An exhaust gas recirculation passage communicating the exhaust manifold of the engine with the intake manifold;
An EGR booster that is disposed in the exhaust gas recirculation passage and pressurizes exhaust gas from the exhaust manifold, and an EGR booster that includes an air turbine that drives the EGR compressor;
An air compressor that supplies pressurized air to the air turbine, and an outside air booster that includes an exhaust turbine that drives the air compressor by exhaust from the exhaust manifold;
An exhaust gas recirculation device for a supercharged engine comprising: The exhaust gas recirculation device for a supercharged engine according to claim 1,
The exhaust gas recirculation passage is branched from an exhaust passage in which the exhaust turbine is disposed and exhausts exhaust from the exhaust manifold, and an intake passage in which the supercharger is disposed and guides pressurized air from the supercharger to the intake manifold. An inlet-side check valve for preventing the backflow of exhaust gas to the exhaust passage side is disposed upstream of the EGR booster of the exhaust recirculation passage, and the exhaust recirculation passage of the exhaust gas recirculation passage is connected to the downstream side of the supercharger. An exhaust gas recirculation device for a supercharged engine, characterized in that an outlet check valve for preventing inflow of intake air from the intake passage is disposed downstream of an EGR booster. The exhaust gas recirculation device for a supercharged engine according to claim 1 or 2,
The exhaust gas recirculation passage is branched from an exhaust passage in which the exhaust turbine is disposed and exhausts exhaust from the exhaust manifold, and an intake passage in which the supercharger is disposed and leads pressurized air from the supercharger to the intake manifold. An exhaust gas recirculation device for a supercharged engine, characterized in that an EGR tank for temporarily storing exhaust gas is disposed in the exhaust gas recirculation passage. The exhaust gas recirculation device for a supercharged engine according to claim 3,
An exhaust gas recirculation device for a supercharged engine, wherein the EGR tank is disposed downstream and upstream of the EGR booster in the exhaust gas recirculation passage. The exhaust gas recirculation device for a supercharged engine according to any one of claims 1 to 4,
The exhaust gas recirculation passage is connected to a downstream side of the supercharger of an intake passage where the supercharger is disposed and guides pressurized air from the supercharger to the intake manifold, and the downstream side of the supercharger of the intake passage An exhaust gas recirculation device for a supercharged engine, wherein an intake throttle portion is disposed between a connection portion of the exhaust gas recirculation passage.

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