JP2005188359A - Internal combustion engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine with a supercharger capable of exhaust recirculation with high efficiency. <P>SOLUTION: This internal combustion engine with a supercharger operates a turbine 3 of a turbo-charger 2 by the exhaust G of the engine 1 and supplies intake air A compressed by a compressor 4 of the turbo-charger 2 to the engine 1 through an inter cooler 11. With this constitution, an exhaust manifold 6 of the engine 1 is connected to the downstream side of the inter cooler 11 through an EGR conduit 18 with the compressor 17 installed to increase the flow rate of the exhaust G to be circulated to the engine 1 with the compressor 17. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a supercharged internal combustion engine equipped with an EGR device.

  Conventionally, in an internal combustion engine with a supercharger to which exhaust gas recirculation (EGR) is applied, exhaust gas diverted from the engine exhaust path is sent to the engine intake path to lower the combustion temperature, thereby generating NOx. (For example, refer to Patent Document 1).

  As shown in FIG. 2, the internal combustion engine with a supercharger includes an engine 1 and a turbocharger 2. The turbocharger 2 includes a turbine 3, a compressor 4, a transmission shaft 5 for connecting the turbine impeller to the compressor impeller, and the like. It consists of

The turbine 3 has an exhaust introduction port connected to the exhaust manifold 6 of the engine 1, an exhaust delivery port communicates with the muffler 8 through an exhaust pipe 7, and a flow path cross-sectional adjustment mechanism (not shown) is provided at the exhaust introduction port. It has been.
The compressor 4 has an intake inlet connected to an air cleaner 10 via an intake pipe 9 and an intake outlet connected to an intake manifold 13 of the engine 1 via an intake pipe 12 having an intercooler 11.

In addition, an upstream end of an EGR pipe 16 in which an EGR cooler 14 and an EGR valve 15 are incorporated in series is connected to the exhaust manifold 6, and the EGR pipe 16 Is connected to the downstream end.
The intercooler 11 is an air-cooled fin-type heat exchanger, and the EGR cooler 14 is a liquid-cooled tubular heat exchanger.

In the supercharged internal combustion engine shown in FIG. 2, when the engine 1 is in an operating state, most of the exhaust G flows from the exhaust manifold 6 into the turbine 3 to drive the compressor 4, and the exhaust pipe 7 and the muffler 8. After being released into the atmosphere.
The compressed air A that flows into the compressor 4 through the air cleaner 10 and the intake pipe 9 and is compressed is supplied to the intake manifold 13 through the intake pipe 12 and the intercooler 11, and at the same time, a part of the exhaust G is exhausted from the exhaust manifold 6. Then, the exhaust gas G flows into the EGR pipe line 16, is cooled by the EGR cooler 14, and the flow rate is adjusted by the EGR valve 15, and is supplied to the intake manifold 13 together with the intake air A.

As a result, the combustion temperature is lowered and the generation of NOx is reduced.
Japanese Patent Laid-Open No. 9-256915

  However, in the conventional turbocharged internal combustion engine shown in FIG. 2, in order to increase the flow rate of the exhaust G fed from the EGR pipe line 16 to the intake manifold 13, let it flow into the turbine 3 by the flow path cross-sectional adjustment mechanism. If the flow rate of the exhaust gas G is suppressed, the pumping loss of the engine 1 increases and fuel consumption becomes excessive.

  In addition, if the flow rate of the exhaust gas G that flows into the turbine 3 is excessively suppressed while the engine 1 is operating in the low speed and high load operation region, the flow rate of the intake air A that passes through the compressor 4 is relatively reduced. There is a concern that the compressor 4 may be damaged by the occurrence of a surge.

  Further, when the vehicle is accelerated, the increase in the flow rate of the exhaust gas G returning from the EGR line 16 into the cylinder of the engine 1 is delayed with respect to the increase in the rotational speed of the engine 1, so that NOx cannot be effectively reduced.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an internal combustion engine with a supercharger that can efficiently perform exhaust gas recirculation.

  In order to achieve the above object, an invention according to claim 1 is provided with an engine and a turbocharger, the turbine of the turbocharger is operated by the exhaust of the engine, and the intake air compressed by the compressor of the turbocharger is passed through the intercooler. In an internal combustion engine with a turbocharger that delivers to the engine, an EGR pipe is provided from the upstream side of the turbine in the engine exhaust path to the downstream side of the compressor in the engine intake path, and exhaust can be pumped toward the engine intake path. A simple air blowing means is incorporated in the EGR pipe.

The invention described in claim 2 uses a motor-driven gas compressor as the blowing means.
According to a third aspect of the present invention, the gas compressor is equipped with power regeneration means.
According to a fourth aspect of the present invention, a bypass passage that can guide exhaust to the engine intake path without passing through the air blowing means is attached to the EGR pipe.

  In the first aspect of the present invention, pressure is applied to the exhaust gas flowing through the EGR pipe by the blowing means, and the flow rate of the exhaust gas to be recirculated to the engine intake path is increased without increasing the pressure of the engine exhaust path. Let

  In the invention according to claim 2, the flow rate of the exhaust gas to be recirculated to the engine intake path is quickly increased by the gas compressor.

  In the third aspect of the invention, the kinetic energy obtained from the exhaust gas by the gas compressor when not driven is converted into electric power by the electric power regeneration means.

  According to the fourth aspect of the present invention, the exhaust gas is caused to flow into the engine intake path by the bypass flow path when the exhaust gas recirculation assistance by the air blowing means is not required.

  (1) In the first aspect of the present invention, the pressure of exhaust gas to be recirculated to the engine intake path is increased by the blowing means to reduce the flow rate of gas passing to the compressor when the engine is operated in the low speed and high load operation region. Therefore, it is possible to increase the amount of exhaust gas recirculated into the engine intake path, thereby preventing surges in the compressor and eliminating the pumping loss when the engine is operating in the high-speed operation region. Can be reduced.

  (2) In the invention described in claim 2, since the exhaust gas recirculation amount to the engine intake flow path can be increased rapidly following the increase in the engine speed by the gas compressor, NOx can be increased even during vehicle acceleration. Can be effectively reduced.

  (3) In the invention described in claim 3, the kinetic energy obtained from the exhaust gas by the gas compressor can be converted into electric power and effectively utilized.

  (4) In the invention according to claim 4, when it is not necessary to assist the exhaust gas recirculation by the gas compressor, the exhaust is led from the bypass flow path to the engine intake path to avoid an increase in the flow path resistance. it can.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of an embodiment of an internal combustion engine with a supercharger according to the present invention. In the figure, the same reference numerals as those in FIG. 2 denote the same components.

In this internal combustion engine with a supercharger, an upstream end of an EGR pipe line 18 in which an EGR cooler 14, an on-off valve 28, a non-volumetric compressor 17 such as a centrifugal type, and an EGR valve 15 are incorporated in series in an exhaust manifold 6 is provided. The downstream end of the EGR pipe line 18 is connected to a location downstream of the intercooler 11 of the intake pipe 12.
The EGR pipe line 18 is accompanied by a bypass flow path 20 that connects the inlet side and the outlet side of the compressor 17 and has a switching valve 19.

  In addition to this, a motor 21 for driving the compressor 17, a pressure sensor 22 for detecting the pressure of the exhaust manifold 6, an accelerator sensor 23 for detecting the accelerator opening by loading the engine 1, and a rotation for detecting the rotational speed of the engine 1 A sensor 24, an intake sensor 25 that detects the inflow amount and temperature of the intake air A, a pressure sensor 26 that detects the pressure on the outlet side of the intercooler 11, fuel injection control, opening adjustment of the EGR valve 15, switching valves 19, 28 A control unit (ECU: Electronic Control Unit) 27 for opening and closing is provided.

The control unit 27 is
A. When the pressure of the exhaust manifold 6 obtained by the pressure sensor 22 exceeds a predetermined value (a value at which an increase in pumping loss becomes remarkable), the recirculation amount of the exhaust G from the EGR pipe 18 to the intake pipe 12 is increased. A function of operating the motor 21 and simultaneously closing the switching valve 19 and opening the switching valve 28;
B. The accelerator opening obtained by the accelerator sensor 23, the pressure on the outlet side of the intercooler 11 obtained by the pressure sensor 26, the rotational speed of the engine 1 obtained by the rotation sensor 24, the inflow amount of the intake air A obtained by the intake sensor 25, and the fuel Based on the injection amount or the like, the recirculation amount of the exhaust G required as the vehicle is accelerated is calculated, and the exhaust G having an amount corresponding to the calculated value is quickly recirculated following the increase in the rotational speed of the engine 1. The function of operating the motor 21,
C. A function of opening the switching valve 19 and closing the switching valve 28 so that the exhaust G flows around the compressor 17 when the motor 21 is not operating;
It has.

  In the supercharged internal combustion engine shown in FIG. 1, when the pressure of the exhaust manifold 6 exceeds a predetermined value during operation of the engine 1, the motor 21 for driving the compressor 17 is activated by the function of A term, and the EGR line 18 Therefore, the flow rate of the exhaust gas G to be returned to the intake manifold 13 is increased, the combustion temperature is lowered, and the generation of NOx is reduced.

That is, when the engine 1 is operating in the low-speed and high-load operation region, the action of suppressing the flow rate of the exhaust G fed to the turbine 3 by a flow path cross-section adjusting mechanism or the like causes the intake A of the compressor 4 of the turbocharger 2 to Even if the passage flow rate is not reduced, the amount of exhaust G to be recirculated to the engine 1 increases, and the occurrence of surge in the compressor 4 can be prevented.
Further, when the engine 1 is operating in the high speed operation region, there is no pumping loss, and fuel consumption can be reduced.

  When the vehicle accelerates, the motor 21 for driving the compressor 17 is actuated by the function of the B term, and the engine G so that the flow rate of the exhaust gas G to be recirculated from the EGR pipe line 18 to the intake manifold 13 matches the calculated value. This increases following the increase in the rotational speed of 1, so that NOx can be effectively reduced even during vehicle acceleration.

When the motor 21 for driving the compressor 17 is not operating, the switching valve 19 is opened and the switching valve 28 is closed by the function of the term C, so that the exhaust G that has passed through the bypass flow path 20 passes from the intake pipe 12 to the intake manifold 13. Inflow.
That is, when it is not necessary to assist the recirculation of the exhaust gas G, the exhaust gas G can bypass the compressor 17 and an increase in flow resistance can be avoided.

  Furthermore, the motor 21 is equipped with power regeneration means composed of an inverter and a battery, and instead of the function of the C term, the motor 21 is driven via the compressor 17 by the exhaust G flowing through the EGR pipe line 18. For example, the kinetic energy obtained from the exhaust G can be converted into electric power and used effectively.

  The supercharger-equipped internal combustion engine of the present invention is not limited to the above-described embodiment, and the exhaust flow path can be switched only by the open / close valve of the bypass line without incorporating the open / close valve in the EGR line. Of course, it is possible to make changes within a range that does not depart from the gist of the present invention.

  The supercharged internal combustion engine of the present invention can be applied to various internal combustion engines including a diesel engine for vehicles.

It is a conceptual diagram which shows an example of embodiment of the internal combustion engine with a supercharger of this invention. It is a conceptual diagram which shows an example of the conventional internal combustion engine with a supercharger.

Explanation of symbols

1 Engine 2 Turbocharger 3 Turbine 4 Compressor 6 Exhaust manifold (engine exhaust path)
11 Intercooler 12 Intake pipe (engine intake path)
17 Compressor (air blowing means)
18 EGR line 20 Bypass line 21 Motor A Intake G Exhaust

Claims (4)

  An internal combustion engine with a supercharger comprising an engine and a turbocharger, wherein the turbocharger turbine is operated by engine exhaust and the intake air compressed by the turbocharger compressor is supplied to the engine via an intercooler. The supercharging system is characterized in that an EGR pipe line is provided from the upstream side of the turbine to the downstream side of the compressor in the engine intake path, and a blowing means capable of pumping exhaust gas toward the engine intake path is incorporated in the EGR pipe. Internal combustion engine with a machine.   The internal combustion engine with a supercharger according to claim 1, wherein a motor-driven gas compressor is used as a blowing means.   The internal combustion engine with a supercharger according to claim 2, wherein a power regeneration means is provided in the gas compressor.   The supercharger-equipped internal combustion engine according to claim 1, wherein a bypass passage capable of guiding exhaust gas to the engine intake passage without passing through the air blowing means is attached to the EGR pipe.

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