JP2012067656A - Egr gas cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EGR (Exhaust Gas Recirculation) gas cooling device, capable of cooling an EGR gas without giving an adverse influence to fuel consumption.SOLUTION: A heater 4 heat-exchanging between the EGR gas flowing in an EGR pipe 3 in a near part of an exhaust manifold 23 and an operation gas is provided in a loop pipe 2 in which the operation gas is encapsulated, a cooler 5 heat-exchanging between the operation gas and the atmosphere is provided in the loop pipe 2 and a regenerator 6 is provided between the cooler 5 and the heater 4 of the loop pipe 2 to form a motor 7 for converting heat of the EGR gas into sound in the loop pipe 2.

Description

  The present invention relates to an EGR gas cooling device that cools EGR gas recirculated to an engine, and relates to an EGR gas cooling device that can cool EGR gas without adversely affecting fuel consumption.

  Conventionally, diesel engines are equipped with an exhaust gas recirculation (EGR) system that circulates exhaust gas through the engine. In the EGR system, the EGR gas having a high temperature taken into the EGR pipe from the exhaust manifold is cooled by the EGR cooler, and the cooled EGR gas is mixed with fresh air and sucked into the engine.

  In the EGR cooler, the EGR gas is cooled by the cooling water. The cooling water is dissipated by the radiator. In this way, the heat of the EGR gas is lost as a cooling loss in the EGR cooler. On the other hand, in order to dissipate the cooling water, a cooling fan is driven by an engine or a motor in the radiator. As described above, the heat of the EGR gas becomes a cooling loss, and the driving of the cooling fan is a factor in reducing the thermal efficiency of the diesel engine.

  In order to reuse the heat of the exhaust gas of the engine, Patent Documents 1 and 2 disclose cooling apparatuses that drive the thermoacoustic engine using the exhaust gas as a heat source to cool intake air or EGR gas.

  Here, the thermoacoustic engine will be briefly described.

  As shown in FIG. 3, a heater 101 that is a heat exchanger that performs heat exchange with a high-temperature heat source, a cooler 102 that is a heat exchanger that performs heat exchange with a low-temperature heat source, and cooling the heater 101 A regenerator 103 that maintains a temperature gradient with the regenerator 102 is arranged side by side in the closed loop tube 104. A working fluid (gas) is enclosed in the loop tube 104. With this configuration, when the air column in the loop tube 104 is locally heated and cooled, part of the heat energy is converted into dynamic energy, and the air column causes self-excited vibration. The resonance frequency is determined by the length of the loop tube 104 and the enclosed gas. From this action, the heater 101, the cooler 102, and the regenerator 103 can be mechanically regarded as the prime mover 105. A dynamic cycle (Stirling cycle) is formed by the gas in the loop tube 104 experiencing a thermodynamic process such as heating, cooling, expansion, and compression. Thus, the prime mover 105 has a function of converting heat from the heat source into sound in the loop tube 104.

  As shown in FIG. 4, a refrigerator 106 is arranged in a loop pipe 104 provided with a prime mover 105 as a passive machine that converts vibration (sound) of an air column in the loop pipe 104 into work. The refrigerator 106 is provided with heat exchangers at both ends of the regenerator 107 in the same manner as the prime mover 105. In the refrigerator 106, when one heat exchanger is cooled as the cooler 108, the other heat exchanger becomes the refrigerator 109, and the temperature decreases. Thus, the refrigerator 106 has a function of converting the sound in the loop tube 104 into cold heat and taking it out.

JP 2005-233485 A JP 2006-2784 A

  In the cooling device of Patent Document 2, the heater of the prime mover uses exhaust gas flowing through the exhaust pipe downstream from the catalyst device as a heat source. However, with this configuration, the prime mover itself has no effect of cooling the EGR gas. Further, downstream of the catalyst device, the exhaust gas temperature is considerably lower than the temperature of the exhaust gas just emerging from the engine exhaust manifold, so the temperature difference between the heater and the cooler in the prime mover is small, and the loop The sound generated in the tube is small. For this reason, even if it is going to drive a refrigerator with this sound and to cool EGR gas, cooling becomes inadequate.

  On the other hand, if the exhaust gas flowing through the exhaust pipe upstream of the catalyst device is used as a heat source, the heat of the exhaust gas is taken away by the heater, so that the temperature of the exhaust gas in the catalyst device decreases and the activity of the catalyst is reduced. Is inhibited.

  Patent Document 1 discloses a cooling device in which a heater of a prime mover uses EGR gas downstream from an EGR valve of an EGR pipe as a heat source, and an exhaust gas flowing through an exhaust pipe upstream of a turbine of a turbocharger as a heat source. A cooling device is disclosed.

  However, in the cooling device using the exhaust gas flowing through the exhaust pipe upstream of the turbine as the heat source, the heat of the exhaust gas is deprived in the heater, so the pressure of the exhaust gas that rotates the turbine decreases and the amount of intake air decreases. There is a harmful effect. Further, in this configuration, the prime mover itself has no effect of cooling the EGR gas.

  In the cooling device using EGR gas as a heat source, there is no adverse effect on the catalyst device and the turbocharger. Further, since the EGR gas is used as the heat source of the prime mover, the EGR gas is cooled in the prime mover. However, downstream of the EGR valve, the temperature of the exhaust gas is lower than the temperature of the exhaust gas just emerging from the exhaust manifold, so the temperature difference between the heater and the cooler in the prime mover is small, and the sound generated in the loop pipe Is small. For this reason, even if it is going to drive a refrigerator with this sound and to cool EGR gas, cooling becomes inadequate.

  In the cooling devices of Patent Documents 1 and 2, engine cooling water is used as a heat source for all the coolers of the prime mover and the refrigerator. However, in this configuration, the engine coolant receives heat in the cooler. When the engine cooling water receives heat, the radiator cooling fan must be driven so much, which consumes fuel and adversely affects fuel consumption.

  Further, the temperature of the engine coolant is about 80 ° C. when the vehicle is traveling steadily. In the thermoacoustic engine, if the temperature difference between the heater and the cooler is small in the prime mover, it is disadvantageous for self-excited vibration, and the sound generated in the loop tube is small. Therefore, the temperature of the cooler is preferably lower than the temperature of the engine coolant.

  Therefore, an object of the present invention is to provide an EGR gas cooling device that can solve the above-described problems and can cool the EGR gas without adversely affecting the fuel consumption.

  In order to achieve the above object, the present invention provides an EGR gas cooling device for cooling EGR gas guided by an EGR pipe from an exhaust manifold of an engine to an intake manifold by a thermoacoustic engine, in a loop pipe filled with a working gas. A heater for exchanging heat between the EGR gas flowing through the EGR pipe and the working gas is installed in the immediate vicinity of the exhaust manifold, and a cooler for exchanging heat between the working gas and the atmosphere is installed in the loop pipe. In addition, a regenerator is installed between the cooler and the heater of the loop tube to constitute a prime mover that converts the heat of the EGR gas into the sound in the loop tube.

  A refrigerator that exchanges heat between the working gas and the intake air that flows through the intake pipe of the engine is installed in the loop pipe, and a second cooler that exchanges heat between the working gas and the atmosphere in the loop pipe And a refrigerator that cools the intake air by converting the sound in the loop tube into cold heat by installing a second regenerator between the refrigerator and the second cooler of the loop tube. It may be configured.

  The present invention exhibits the following excellent effects.

  (1) EGR gas can be cooled without adversely affecting fuel consumption.

It is a block diagram of the thermoacoustic engine used for the EGR gas cooling device which shows one Embodiment of this invention. It is a block diagram of the engine system carrying the EGR gas cooling device which shows one Embodiment of this invention. It is a block diagram of the thermoacoustic engine provided with the motor | power_engine. It is a block diagram of the thermoacoustic engine provided with the motor | power_engine and the refrigerator.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  The EGR gas cooling device according to the present invention is an EGR gas cooling device that cools EGR gas guided by an EGR pipe from an exhaust manifold of an engine to an intake manifold by a thermoacoustic engine.

  As shown in FIG. 1, the EGR gas cooling device 1 according to the present invention performs heat exchange between the working gas and the EGR gas flowing through the EGR pipe 3 in the vicinity of the exhaust manifold in the loop pipe 2 in which the working gas is sealed. A heater 4 is installed. The loop pipe 2 is provided with a cooler (hereinafter referred to as a first cooler) 5 for exchanging heat between the working gas and the atmosphere. A regenerator (hereinafter referred to as a first regenerator) 6 is installed between the first cooler 5 and the heater 4 of the loop tube 2. In this way, by arranging the heater 4, the first regenerator 6, and the first cooler 5 side by side, the prime mover 7 that converts the heat of the EGR gas into the sound in the loop tube 2 is configured.

  In the present embodiment, a refrigerator 9 is further installed in the loop pipe 2 for exchanging heat between the working gas and the intake air flowing through the intake pipe 8 of the engine. Further, a second cooler 10 for exchanging heat between the working gas and the atmosphere is installed in the loop pipe 2. A second regenerator 11 is installed between the refrigerator 9 and the second cooler 10 of the loop pipe 2. In this way, the refrigerator 9, the second regenerator 11, and the second cooler 10 are arranged side by side, so that the refrigerator 12 that cools the intake air by converting the sound in the loop pipe 2 to cold is configured. Is done.

  Examples of the working gas sealed in the loop tube 2 include air, helium, nitrogen, and argon.

  In the heater 4, fins (not shown) are provided inside and outside the loop tube 2. Here, for example, the EGR pipe 3 is provided so as to cover the entire outer periphery of the loop pipe 2 including the fins outside the loop pipe 2. Heat exchange can be performed between the EGR gas and the working gas via these fins.

  In the refrigerator 9, fins (not shown) are provided inside and outside the loop tube 2. Here, for example, the intake pipe 8 is provided so as to cover the entire outer periphery of the loop pipe 2 including the fins outside the loop pipe 2. Heat can be exchanged between the working gas and the intake air through these fins.

  In the first cooler 5 and the second cooler 10, fins (not shown) are provided inside and outside the loop pipe 2. Heat can be exchanged between the working gas and the atmosphere via the fins of these coolers 5 and 10. The air cooling fan 13 may be installed facing the outer fin.

  The first regenerator 6 and the second regenerator 11 are composed of a wire mesh, a collection of a plurality of thin tubes, a porous ceramic and the like.

  In addition, since the well-known thing can be used for the heater 4, the refrigerator 9, the 1st cooler 5, the 2nd cooler 10, the 1st regenerator 6, and the 2nd regenerator 11, it has detailed structure. Description is omitted. The cross-sectional shape, thickness, length, and loop shape of the loop tube 2 are not particularly limited here.

  As shown in FIG. 2, in the engine system 21 equipped with the EGR gas cooling device 1 of the present invention, the EGR pipe 3 is branched from the exhaust manifold 23 of the engine 22, and the most downstream of the EGR pipe 3 is connected to the intake manifold 24. Connected. An EGR cooler 25 and an EGR valve 26 are provided in the middle of the EGR pipe 3. The position of the heater 4 is upstream of the EGR cooler 25 and the EGR valve 26 and is closest to the exhaust manifold 23 (position as close as possible).

  An exhaust pipe 27 is branched from the exhaust manifold 23, and the most downstream side of the exhaust pipe 27 is opened to the atmosphere. A turbine 29 of a turbocharger 28 is provided in the middle of the exhaust pipe 27, and an exhaust gas purification device 30 such as a DOC (Diesel Oxidation Catalyst) and a DPF (Diesel Particulate Filter) is provided downstream of the turbine 29.

  The intake manifold 24 is connected to the intake pipe 8 from the outlet of the compressor 31 of the turbocharger 28. An intake throttle (not shown) and an intercooler 32 are provided in the middle of the intake pipe 8. An intake pipe 8 from the atmosphere is connected to the inlet of the compressor 31. The position of the refrigerator 9 is preferably between the intercooler 32 and the intake manifold 24.

  Hereinafter, the operation of the EGR gas cooling device 1 will be described with reference to FIGS. 1 and 2.

  The exhaust gas of the engine 22 flows from the exhaust manifold 23 into the EGR pipe 3 and the exhaust pipe 27. The EGR gas flowing through the EGR pipe 3 passes through the heater 4 and flows into the intake manifold 24 through the EGR cooler 25 and the EGR valve 26. At this time, in the heater 4, heat exchange between the EGR gas and the working gas in the loop pipe 2 is performed. On the other hand, in the first cooler 5, heat exchange between the atmosphere and the working gas in the loop pipe 2 is performed. As a result, a temperature gradient is formed in the first regenerator 6 between the heater 4 and the first cooler 5, the air column in the loop tube 2 causes self-excited vibration, and sound is generated.

  The EGR gas flowing through the EGR pipe 3 is cooled by exchanging heat with the heater 4. This cooling increases the density of the EGR gas flowing into the intake manifold 24, so that the expansion work performed by the engine 22 increases and the thermal efficiency of the engine 22 increases.

  The exhaust gas flowing into the exhaust pipe 27 is driven by the turbine 29 and then purified by the exhaust gas purification device 30 downstream of the exhaust pipe 27 and released to the atmosphere.

  The intake air taken into the intake pipe 8 from the atmosphere is compressed by the compressor 31, cooled by the intercooler 32, passes through the refrigerator 9, and flows into the intake manifold 24. At this time, in the second cooler 10, heat exchange between the atmosphere and the working gas in the loop pipe 2 is performed. Thereby, since the temperature of the working gas in the second cooler 10 becomes the atmospheric temperature, the temperature gradient of the second regenerator 11 between the second cooler 10 and the freezer 9 causes the working gas in the freezer 9 to flow. The temperature is lower than the atmospheric temperature. For this reason, the intake air flowing through the intake pipe 8 is cooled and the density of the intake air flowing into the intake manifold 24 increases, so that the expansion work performed by the engine 22 increases and the thermal efficiency of the engine 22 increases.

  According to the EGR gas cooling device 1 of the present invention, since the prime mover 7 that converts the heat of the EGR gas into the sound in the loop pipe 2 is configured, in the radiator that cools the EGR gas and cools the cooling water of the EGR cooler 25 The work of driving the cooling fan is reduced, and the thermal efficiency of the engine 22 is improved.

  According to the EGR gas cooling device 1 of the present invention, heat is exchanged between the working gas and the EGR gas that flows in the vicinity of the exhaust manifold 23 in the heater 4 of the prime mover 7. The hot EGR gas becomes a heat source. As a result, the temperature difference between the heater 4 and the first cooler 5 in the prime mover 7 increases, and the sound generated in the loop pipe 2 increases, so that the heat of the EGR gas is greatly deprived in the heater 4 and the EGR gas. Is cooled well.

  According to the EGR gas cooling device 1 of the present invention, since engine cooling water is not used as the heat source of the coolers 5 and 10, heat input to the engine cooling water is small, and the driving request for the cooling fan of the radiator is alleviated. For this reason, consumption of fuel is suppressed and fuel consumption is improved.

  According to the EGR gas cooling device 1 of the present invention, since the fins of the coolers 5 and 10 are cooled in the atmosphere, no special cooling heat source is required. Further, while the engine coolant temperature during traveling of the vehicle is about 80 ° C., the temperature of the atmosphere is lower than that, so the temperature difference between the heater 4 and the first cooler 5 becomes large in the prime mover 7. . Thereby, self-excited vibration is facilitated and the sound generated in the loop tube 2 is increased.

  The cooling fan 13 may be provided so as to face the fins of the coolers 5 and 10. However, since there is an air flow passing through the fins in the engine room while the vehicle is running, a sufficient cooling effect can be obtained with only the fins. It is done. Therefore, the cooling fan 13 need only be driven when the air cooling effect is poor, such as when the vehicle is stopped, and does not adversely affect the fuel consumption.

  According to the EGR gas cooling device 1 of the present invention, in addition to the prime mover 7 that converts the heat of the EGR gas into the sound in the loop pipe 2, the refrigeration that cools the intake air by converting the sound in the loop pipe 2 into cold heat. Since the machine 12 is configured, not only the EGR gas can be cooled, but also the intake air can be cooled by working with the deprived heat.

  In particular, in downsizing for reducing the size of the engine 22 and its peripheral members that have been requested in recent years, the EGR gas temperature and the intake air temperature are higher than before downsizing. On the other hand, the radiator cooling fan uses most of its capacity to cool the engine coolant, so there is no room for cooling the EGR cooler 25 and the intercooler 32. Therefore, it is very useful for downsizing that the EGR gas and the intake air can be cooled by the thermoacoustic engine as in the present invention.

  In the present embodiment, the intake air is cooled by the refrigerator 12, but heat is exchanged between the working gas and the EGR gas flowing downstream from the installation location of the heater 4 in the refrigerator 9 of the refrigerator 12. The EGR gas may be cooled by the refrigerator 12. The prime mover that extracts work from the sound in the loop tube 2 is not limited to the refrigerator 12.

1 EGR gas cooling device 2 Loop pipe 3 EGR pipe 4 Heater 5 Cooler (first cooler)
6 Regenerator (first regenerator)
7 prime mover 8 intake pipe 9 refrigerator 10 second cooler 11 second regenerator 12 refrigerator

Claims (2)

An EGR gas cooling device for cooling EGR gas guided by an EGR pipe from an exhaust manifold of an engine to an intake manifold by a thermoacoustic engine,
A heater for exchanging heat between the working gas and the EGR gas flowing in the EGR pipe in the vicinity of the exhaust manifold is installed in the loop pipe filled with the working gas.
In the loop pipe, a cooler for exchanging heat between the working gas and the atmosphere is installed,
An EGR gas cooling device comprising a prime mover for converting the heat of EGR gas into sound in the loop tube by installing a regenerator between the cooler and the heater of the loop tube. . The loop pipe is provided with a refrigerator that exchanges heat between the working gas and the intake air flowing through the intake pipe of the engine,
A second cooler for exchanging heat between the working gas and the atmosphere is installed in the loop pipe,
A refrigerating machine configured to cool the intake air by converting the sound in the loop pipe to cold by installing a second regenerator between the freezer and the second cooler of the loop pipe is configured. The EGR gas cooling device according to claim 1.

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