JP2004270625A - Device for recovering exhaust heat energy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently utilize recovery exhaust heat energy of an internal combustion engine. <P>SOLUTION: This device for recovering exhaust heat energy includes a heater 11 of an external combustion engine 23 capable of exchanging heat with an exhaust system of an internal combustion engine 7 and a cooler 5 for the engine 23 capable of exchanging heat with an intake system of the engine 7. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an exhaust heat energy recovery device that recovers exhaust heat energy of an internal combustion engine for use as drive energy of an external combustion engine.
[0002]
[Prior art]
Patent Document 1 discloses a method in which an exhaust purification catalyst is interposed in an exhaust system of an internal combustion engine and the catalyst is connected to a heating unit of an external combustion engine such as a Stirling engine.
[0003]
[Patent Document 1]
JP-A-2002-266701
[Problems to be solved by the present invention]
However, in Patent Literature 1, since the heating section of the external combustion engine receives heat from the exhaust gas purification catalyst, the time until the temperature of the catalyst increases, that is, the time during which exhaust gas that is not purified after the internal combustion engine is started is discharged for a long time. There was a problem of becoming. Patent Document 1 discloses a method in which catalysts are arranged in parallel, one of the catalysts only purifies exhaust gas, and the other catalyst is connected to a heating unit of an external combustion engine. Even in the case of the other catalyst, the time for discharging the exhaust gas that is not purified after the start of the internal combustion engine remains the same as in the above-described embodiment.
[0005]
Therefore, an object of the present invention is to utilize the exhaust heat energy of the internal combustion engine as the drive energy of the external combustion engine without increasing the temperature rise time of the catalyst.
[0006]
[Means for Solving the Problems]
The exhaust heat energy recovery device of the present invention is provided with a heater of the external combustion engine so as to be able to exchange heat with the exhaust system of the internal combustion engine, and is provided with a cooler of the external combustion engine so that it can exchange heat with the intake system of the internal combustion engine. It is characterized by the following.
[0007]
[Action / Effect]
According to the present invention, the heating section of the external combustion engine is heated by heat exchange with the exhaust system of the internal combustion engine, and the cooling section of the external combustion engine is cooled by heat exchange with the intake system of the internal combustion engine, so that the external combustion engine is cooled. Since the engine (the Stirling engine) is driven, it becomes possible to recover the exhaust heat energy of the internal combustion engine as the drive energy of the external combustion engine. For example, if a generator is provided on the crankshaft of the Stirling engine, the heat energy of the exhaust gas discharged from the internal combustion engine by driving the Stirling engine can be recovered as electric power, and this electric power is used for driving auxiliary equipment and the like. As a result, the power generation amount of the alternator can be reduced, the fuel consumption can be reduced, and the fuel consumption can be improved.
[0008]
Further, the intake air of the internal combustion engine heated by heat exchange with the cooling unit of the external combustion engine expands, and the air density decreases. As a result, the throttle opening increases in order to obtain the same torque as in the case where the intake air is not heated, and the pressure in the intake manifold increases, so that pumping loss is reduced and fuel efficiency can be improved.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0010]
FIG. 1 is a diagram showing the configuration of the system according to the first embodiment. Reference numeral 7 denotes an engine, 6 denotes an intake passage of the engine 7, and 8 denotes an exhaust passage.
[0011]
In the intake passage 6, an air cleaner 1, an air flow meter 2a for measuring the amount of intake air passing through the air cleaner 1, and an intake air temperature sensor 2b for measuring the intake air temperature are arranged. A throttle valve 3 to be adjusted is arranged.
[0012]
A part of the intake passage 6 downstream of the throttle valve 3 is branched into an intake bypass passage 21 and a cooler-side passage 24, and one of the intake passages is selectively operated by an intake passage switching valve 4 provided in the intake passage 6. Is closed. The cooler 5 of the Stirling engine 23 as an external combustion engine described later is provided in the cooler side passage 24.
[0013]
An exhaust purification catalyst 9 is provided in the exhaust passage 8, and a part of the downstream of the exhaust purification catalyst 9 is branched into a heater-side passage 25 and an exhaust bypass passage 22, and an exhaust passage provided in the exhaust passage 8 is provided. Either one is selectively closed by the switching valve 10. The heater 11 of the Stirling engine 23 as an external combustion engine described later is provided in the heater-side passage 25.
[0014]
The heater 11 and the cooler 5 are connected via a regenerator 12.
[0015]
The Stirling engine 23 has a displacer cylinder 26 and a power cylinder 27. A displacer piston 13 for stirring which defines an expansion chamber 28 on the head side and a compression chamber 29 on the bottom side is slidably disposed in the displacer cylinder 26, and the head is disposed in the power cylinder 27. A power piston 14 that defines an operating chamber 30 that communicates with the compression chamber 29 via a port 32 is slidably mounted on the unit side. The expansion chamber 28 is connected to the heater 11 by a heating pipe 18, and the compression chamber 29 is connected to the cooler 5 by a cooling pipe 17.
[0016]
The displacer piston 13 and the power piston 14 are connected to the crankshaft 16 via connecting rods 35 and 36, respectively. At this time, the power piston 14 is connected to the displacer piston 13 such that the phase is delayed by about 90 degrees at the crank angle.
[0017]
One end of the crankshaft 16 is connected to the generator 15 via a flywheel 33. Thus, the generator 15 is driven by the rotation of the crankshaft 16.
[0018]
The operation of the system configured as described above will be described.
[0019]
During operation of the engine 7, the intake bypass passage 21 and the exhaust bypass passage 22 are closed in principle. Further, when the intake bypass passage 21 is closed, the exhaust bypass passage 22 is closed, and when the cooler side passage 24 is closed, the heater side passage 25 is closed.
[0020]
The intake air sucked from the air cleaner 1 exchanges heat with the cooler 5 when passing through the cooler side passage 24. As a result, the intake air is heated and the working gas of the Stirling engine 23 in the cooler 5 is cooled, so that the compression chamber 29 communicating with the cooler 5 is cooled by the cooling pipe 17.
[0021]
The exhaust gas discharged from the engine 7 exchanges heat with the heater 11 when passing through the heater-side passage 25. Accordingly, the exhaust gas is cooled, and the working gas of the Stirling engine 23 in the heater 11 is heated, so that the heating pipe 18 heats the expansion chamber 28 communicating with the heater 11.
[0022]
Therefore, the Stirling engine 23 is driven by the displacer piston 13 agitating the heated working gas and the cooled working gas in the displacer cylinder 26, and the generator 15 connected to the Stirling engine 23 is also driven to generate power. I do.
[0023]
This makes it possible to recover the heat energy of the exhaust gas of the engine 7 as electric power.
[0024]
Further, since the intake air becomes high temperature by exchanging heat with the cooler 5 and expands, the air density of the intake manifold 34 decreases. Therefore, when an equal torque is to be obtained, it is necessary to increase the opening of the throttle valve 3 as compared with the case where the intake air is at a low temperature, and as a result, the pressure of the intake manifold 34 increases. As a result, the pumping loss can be reduced, so that the fuel efficiency can be improved. Particularly, in the present embodiment, since the cooler 5 is disposed downstream of the throttle valve 3, it is possible to efficiently increase the pressure of the intake manifold 34.
[0025]
However, if the temperature of the intake air rises too much, there is a problem that the combustion temperature rises and knocking easily occurs.
[0026]
Therefore, when knock sensor 20 provided in engine 7 detects knocking, intake passage switching valve 4 and exhaust passage switching valve 10 are controlled such that intake air passes through intake bypass passage 21 and exhaust gas passes through exhaust bypass passage 22. I do. As a result, knocking due to high temperature of the intake air can be avoided. A control unit (ECM) 19 is provided to control these operations. Here, the contents of the control performed by the ECM 19 will be described in more detail according to the flowchart of FIG.
[0027]
In step S101, it is determined whether or not the knocking sensor 20 has detected knocking. If the knocking has been detected, the process proceeds to step S102. In step S102, it is determined whether or not the cooler-side passage 24 and the heater-side passage 25 are open. If the cooler-side passage 24 and the heater-side passage 25 are open, the process proceeds to step S103. Close. If it has not been released, it is left as it is.
[0028]
If knocking is not detected in step S101, the process proceeds to step S104, in which it is determined whether the cooler-side passage 24 and the heater-side passage 25 are open. If it is not released, the process proceeds to step S105, where the cooler-side passage 24 and the heater-side passage 25 are opened.
[0029]
By the way, when the outside air is at high temperature, the engine 7 is in a severe condition such that knocking is likely to occur. For example, when the detection value of the intake air temperature sensor 2b exceeds a predetermined value, Similarly, the ECM 19 controls the intake passage switching valve 4 and the exhaust passage switching valve 10 so that the intake air passes through the intake bypass passage 21 and the exhaust gas passes through the exhaust bypass passage 22.
[0030]
FIG. 3 is a flowchart of the above control executed by the ECM 19.
[0031]
In step S201, the intake air temperature measured by the intake air temperature sensor 2b is compared with a predetermined value. If the intake air temperature exceeds the predetermined value, the process proceeds to step S202, where the cooler-side passage 24 and the heater-side passage 25 To close. If the intake air temperature is lower than the predetermined value, the process proceeds to step S203, where it is determined whether or not the cooler-side passage 24 and the heater-side passage 25 are open. If not, the process proceeds to step S105, where the cooler-side passage 24 and the heater-side passage 25 are opened. When the temperature of the engine cooling water becomes extremely high, the temperature of the engine 7 rises and knocking easily occurs. Therefore, a method of performing the same control as in FIG. 3 by using the water temperature sensor 37 instead of the outside air temperature in FIG. 3 may be considered.
[0032]
As described above, in the present embodiment, the following effects can be obtained.
[0033]
The cooler 5 and the heater 11 of the Stirling engine 23, which is an external combustion engine, are arranged so as to be able to exchange heat with the intake passage 6 and the exhaust passage 8 of the engine 7, which is an internal combustion engine. Since the generator 15 is driven, it is possible to recover the heat energy of the exhaust gas as electric power. By using this electric power to drive auxiliary equipment, the amount of power generated by the alternator and the like can be reduced, so that fuel consumption can be reduced and fuel efficiency can be improved.
[0034]
Since the heater 11 does not directly receive the heat from the exhaust purification catalyst 9 as in the above-described conventional example, the temperature rise of the exhaust purification catalyst 9 is not hindered after the engine 7 starts, and the exhaust gas Does not get worse.
[0035]
The intake air expands due to heat exchange with a cooler 5 provided downstream of the throttle valve 3. As a result, when the torque generated by the engine 7 is equal, the intake manifold pressure is higher than when the intake air is not heated, so that pumping loss can be reduced and fuel efficiency can be improved.
[0036]
When the intake air temperature, the outside air temperature, and the cooling water temperature rise and the engine 7 becomes thermally severe, heat exchange between the cooling unit 5 and the heating unit 11 and the intake air is stopped. Failure can be prevented.
[0037]
It is needless to say that the present invention is not limited to the above embodiment, and various changes can be made within the scope of the technical idea described in the claims.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a system configuration according to a first embodiment.
FIG. 2 is a flowchart of control based on knocking detection according to the first embodiment.
FIG. 3 is a flowchart of control based on an outside air temperature or a cooling water temperature according to the first embodiment.
[Explanation of symbols]
1 air cleaner 2a air flow meter (AFM)
2b Intake air temperature sensor 3 Throttle valve 4 Intake passage switching valve (intake passage switching means)
Reference Signs List 5 cooler 6 intake passage 7 engine 8 exhaust passage 9 exhaust purification catalyst 10 exhaust passage switching valve (exhaust passage switching means)
DESCRIPTION OF SYMBOLS 11 Heater 12 Regenerator 13 Displacer piston 14 Power piston 15 Generator 16 Crankshaft 17 of Stirling engine Cooling pipe 18 Heating pipe 19 Control unit (ECM) (intake and exhaust passage control means)
Reference Signs List 20 knocking sensor 21 intake bypass passage 22 exhaust bypass passage 23 Stirling engine 24 cooler side passage 25 heater side passage 26 displacer cylinder 27 power cylinder 28 expansion chamber 29 compression chamber 30 working chamber 32 port 33 flywheel 34 intake manifold 35 connecting rod 36 Connecting rod 37 Water temperature sensor

Claims (8)

A heater of the external combustion engine is provided so as to be able to exchange heat with the exhaust system of the internal combustion engine,
An exhaust heat energy recovery device, wherein a cooler of the external combustion engine is provided so as to exchange heat with an intake system of the internal combustion engine. In the intake passage of the internal combustion engine,
An intake bypass passage having an inlet upstream of the cooler and an outlet downstream and bypassing the cooler,
At least one of the vicinity of an inlet and the vicinity of an outlet of the intake bypass passage is provided with intake passage switching means for cutting off communication between any one of the intake bypass passage and the intake passage,
In the exhaust passage of the internal combustion engine,
An exhaust bypass passage having an inlet upstream of the heater and an outlet downstream and bypassing the heater;
At least one of the vicinity of the inlet and the outlet of the exhaust bypass passage is provided with exhaust passage switching means for cutting off communication with any one of the exhaust bypass passage and the exhaust passage,
The exhaust heat energy recovery device according to claim 1, further comprising an intake / exhaust passage control unit that controls the intake passage switching unit and the exhaust passage switching unit. 3. The exhaust heat energy recovery device according to claim 1, wherein the cooler is provided in an intake passage downstream of a throttle valve that adjusts an intake air amount of the internal combustion engine. The exhaust heat energy recovery device according to any one of claims 1 to 3, wherein the heater is provided in an exhaust passage downstream of an exhaust purification catalyst provided in an exhaust system of the internal combustion engine. 5. The exhaust system according to claim 2, wherein a knocking detecting means is provided in the internal combustion engine, and when knocking is detected, the intake passage control valve selects the intake bypass passage at least for an intake passage. Thermal energy recovery device. The bypass passage is selected for both the intake passage and the exhaust passage when the outside air temperature or the cooling water temperature of the internal combustion engine exceeds a predetermined value. Exhaust heat energy recovery device. The exhaust heat energy recovery device according to any one of claims 1 to 6, wherein the external combustion engine is a Stirling engine. The exhaust thermal energy recovery device according to claim 7, wherein a generator is connected to a crankshaft of the Stirling engine.

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