JP2012112307A - Exhaust heat recovering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust heat recovering system that suppresses lowering a recovery efficiency of an exhaust heat.SOLUTION: The exhaust heat recovering system includes: a starring engine having a cooler for cooling a working fluidity that receiving heat from the exhaust gas of a thermomotor; an radiator that is connected to the cooler via a passage through which a coolant passes, and between which and the cooler the coolant circulates; and an air conduit for the radiator that guides blowing air of the fan used for sending air into a cabin of a vehicle on which the radiator is mounted to the radiator.

Description

  The present invention relates to an exhaust heat recovery system.

  Patent Document 1 discloses an exhaust heat recovery device that recovers exhaust heat of exhaust gas from a heat engine. A Stirling engine is known as such an exhaust heat recovery device. The Stirling engine uses exhaust gas as a high-temperature heat source, uses a cooler provided in the Stirling engine as a low-temperature heat source, and utilizes the change in the state of the working fluid between the high-temperature heat source and the low-temperature heat source to generate heat from the exhaust gas. Energy is taken out as motive energy.

JP 2007-231858 A

  Depending on the operating state of the heat engine, the temperature of the exhaust gas may be low. In such a case, the temperature difference between the high-temperature heat source and the low-temperature heat source becomes small, and the exhaust heat recovery efficiency may be reduced.

  Therefore, an object is to provide an exhaust heat recovery system that suppresses a decrease in exhaust heat recovery efficiency.

  The above problem is between a Stirling engine having a cooler for cooling a working fluid that receives heat from the exhaust gas of the heat engine, and the cooler connected to the cooler through a passage through which a refrigerant passes. Achieved by an exhaust heat recovery system comprising: a radiator in which the refrigerant circulates; and a fan air passage for guiding a fan to send air to the interior of a vehicle in which the heat engine is mounted. it can.

  By dissipating the refrigerant that passes through the cooler that cools the working fluid with the radiator, the temperature of the cooler that is the low-temperature heat source of the working fluid can be lowered. Thereby, the fall of the recovery efficiency of the exhaust heat in a Stirling engine is suppressed.

  Further, the object is to connect the Stirling engine having a cooler for cooling the working fluid that receives heat from the exhaust gas of the heat engine and the cooler through a passage through which the refrigerant passes, This can be achieved by an exhaust heat recovery system that includes an evaporator of an air conditioner that cools the interior of a vehicle mounted.

  When the refrigerant passing through the cooler that cools the working fluid passes through the evaporator of the air conditioner, the temperature of the cooler that is a low-temperature heat source of the working fluid can be lowered. Thereby, the fall of the recovery efficiency of the exhaust heat in a Stirling engine is suppressed.

  An exhaust heat recovery system that suppresses a decrease in exhaust heat recovery efficiency can be provided.

FIG. 1 is an explanatory diagram of a waste heat recovery system according to the first embodiment. FIG. 2 is an explanatory diagram of the ECU. FIG. 3 is an explanatory diagram of a Stirling engine. FIG. 4 is a flowchart showing an example of air volume control to the second radiator that is executed by the ECU. FIG. 5 is an explanatory diagram of the exhaust heat recovery system according to the second embodiment. FIG. 6 is an explanatory diagram of the exhaust heat recovery system according to the third embodiment. FIG. 7 is an explanatory diagram of a refrigerant path that circulates between the air conditioner and the Stirling engine.

  Hereinafter, a plurality of embodiments will be described.

  FIG. 1 is an explanatory diagram of a waste heat recovery system according to the first embodiment. The exhaust heat recovery system 100 includes a heat engine 1, a Stirling engine 1a that recovers exhaust heat of the heat engine 1, and the like. The heat engine 1 may be a gasoline engine, a diesel engine, a gas engine, or the like, and may be of any type. The Stirling engine 1a is a Stirling engine, but may be any engine that converts temperature energy into engine energy.

  In the first embodiment, the exhaust heat recovery system 100 is mounted on a vehicle, and the heat engine 1 is used as a main engine for driving the vehicle, but is not limited thereto. A cooling water passage W <b> 1 through which cooling water for cooling the heat engine 1 passes is connected to the heat engine 1. The cooling water passages W <b> 1 are connected to the heat engine 1, the radiator 5, and the first radiator 93 so that the cooling water circulates between them. Valves V1 and V2 and a pump P1 are disposed on the cooling water passage W1.

  The exhaust heat recovery system 100 is provided with an air conditioner AC. The air conditioner AC includes an evaporator 81. The blower fan 8 is for sending air into the vehicle. As the blower fan 8 rotates, air passes through the evaporator 81. Further, the air exposed to the evaporator 81 is guided into the vehicle through the air passage 70. The evaporator 81 is disposed in the air passage 70.

  The air passage 70 includes an indoor air passage 72 and a radiator air passage 74 that are branched in the middle of each other. The indoor air passage 72 guides air from the blower fan 8 into the vehicle interior. Further, the indoor air passage 72 is provided with a bypass passage 73 that branches from the indoor air passage 72 in the middle and merges with the indoor air passage 72 again.

  A first radiator 93 in which the cooling water from the heat engine 1 circulates is disposed in the bypass passage 73. When the air blown from the blower fan 8 passes through the first radiator 93, the heat radiation of the cooling water in the first radiator 93 is promoted. Thereby, the air receives heat from the first radiator 93 and the temperature rises.

  Further, a temperature adjusting valve V3 is provided at a branch portion between the indoor air passage 72 and the bypass passage 73. The temperature adjustment valve V3 is rotatably supported between a state in which the indoor air passage 72 is opened and the bypass passage 73 is closed, and a state in which the indoor air passage 72 is closed and the bypass passage 73 is opened. Therefore, at the time of heating, for example, the temperature adjustment valve V3 closes the indoor air passage 72 side and opens the bypass passage 73 side, whereby the air heated by the first radiator 93 is guided into the vehicle interior. Thus, the temperature adjustment valve V3 has a function of adjusting the temperature of the air guided into the passenger compartment. The first radiator 93 corresponds to an indoor radiator.

  The radiator air passage 74 guides the air from the blower fan 8 to the outside of the vehicle. A second radiator 94 in which the refrigerant circulates with the Stirling engine 1a via the refrigerant passage W10 is disposed in the radiator air passage 74. Specifically, the refrigerant passage W10 is a hose or the like. A pump P2 is disposed in the refrigerant passage W10. The second radiator 94 will be described later.

  Further, the air flow control valve V4 is provided in the radiator air passage 74. By adjusting the opening degree of the air volume control valve V4, it is possible to change the proportion of the flow rate of the air flowing through the indoor air passage 72 and the radiator air passage 74, respectively. Therefore, the air volume control valve V4 has a function of controlling the air volume of the air guided into the vehicle interior. Note that any of the temperature adjusting valve V3 and the air volume control valve V4 can be stopped at a predetermined opening degree. The temperature adjustment valve V3 and the air volume control valve V4 are driven by an actuator such as a step motor that can be stopped in a non-energized state, for example.

  FIG. 2 is an explanatory diagram of the ECU. The above-described driving of the valves V1, V2, the temperature adjustment valve V3, the air volume control valve V4, the pumps P1, P2, and the blower fan 8 is controlled by the ECU 10. The ECU 10 is a computer using ROM, RAM, and CPU. The ROM stores a program for executing air volume control to the second radiator 94 described later. Further, the detection result of the room temperature sensor TS arranged in the vehicle interior is output to the ECU 10.

  Next, the Stirling engine 1a will be described. FIG. 3 is an explanatory diagram of the Stirling engine 1a. The Stirling engine 1a is an α-type (two-piston type) Stirling engine, and includes a high temperature side cylinder 20 and a low temperature side cylinder 30 arranged in series. The high temperature side cylinder 20 has an expansion piston 21 and a high temperature side cylinder 22, and the low temperature side cylinder 30 has a compression piston 31 and a low temperature side cylinder 32, respectively. The compression piston 31 moves about 90 ° behind the expansion piston 21 with a crank angle.

  The upper space of the high temperature side cylinder 22 is an expansion space. The working fluid heated by the heater 47 flows into the expansion space. The heater 47 is disposed in the exhaust pipe 3 of the heat engine 1, and the working fluid is heated by the thermal energy recovered from the exhaust gas. The upper space of the low temperature side cylinder 32 is a compression space. The working fluid cooled by the cooler 45 flows into the compression space. The regenerator 46 exchanges heat with the working fluid reciprocating between the expansion space and the compression space. Specifically, the regenerator 46 receives heat from the working fluid when the working fluid flows from the expansion space to the compression space, and releases the stored heat to the working fluid when the working fluid flows from the compression space to the expansion space. . Air is applied to the working fluid. However, the present invention is not limited to this, and a gas such as He, H2, or N2 can be applied to the working fluid.

  Next, the operation of the Stirling engine 1a will be described. When the working fluid is heated by the heater 47, it expands and the expansion piston 21 is pressed down, whereby the drive shaft 65 is rotated. Next, when the expansion piston 21 moves to the ascending stroke, the working fluid passes through the heater 47 and is transferred to the regenerator 46 where heat is released and flows to the cooler 45. The working fluid cooled by the cooler 45 flows into the compression space, and is further compressed as the compression piston 31 moves upward. The working fluid thus compressed rises in temperature while taking heat from the regenerator 46 and flows into the heater 47 where it is heated and expanded again. That is, the Stirling engine 1a operates through the reciprocating flow of the working fluid. The Stirling engine 1a supports the connecting rod 60 by a grasshopper mechanism 50.

  In the cooler 45 of the Stirling engine 1a, the refrigerant circulates with the second radiator 94 via the refrigerant passage W10. The pump P2 is for circulating the refrigerant between the cooler 45 and the second radiator 94 of the Stirling engine 1a. As described above, the refrigerant passing through the cooler 45 flows in the second radiator 94 disposed in the radiator air passage 74, so that the refrigerant can be radiated by the second radiator 94. In particular, when the air conditioner AC is in a driving state and the air cooled after passing through the evaporator 81 flows to the second radiator 94, the refrigerant can be radiated effectively. Thereby, the temperature of the cooler 45 that functions as a low-temperature heat source of the Stirling engine 1a can be further reduced. Thereby, for example, even when the exhaust gas is at a low temperature depending on the operating state of the heat engine 1, the temperature of the working fluid cooled by the cooler 45 can be further cooled to suppress a reduction in exhaust heat recovery efficiency. . The refrigerant is not limited to water but may be carbon dioxide, chlorofluorocarbon, or the like.

  Next, air volume control to the second radiator 94 executed by the ECU 10 will be described. FIG. 4 is a flowchart showing an example of air volume control to the second radiator 94 executed by the ECU 10. In the following flowchart, the air volume control executed by the ECU 10 when the air conditioner AC is driven will be described.

  The ECU 10 determines whether or not the current room temperature is a required value (step S1). Specifically, the ECU 10 grasps the current room temperature based on the output value from the room temperature sensor TS, and determines whether or not the current room temperature is the same as the desired room temperature set by the user. In the case of an affirmative determination, assuming that the air volume into the passenger compartment is sufficient, the ECU 10 increases the air volume flowing from the blower fan 8 to the second radiator 94 by increasing the opening of the air volume control valve V4 (step S2). ). Thereby, the refrigerant | coolant which flows through the cooler 45 of the Stirling engine 1a can be thermally radiated effectively, and the fall of the collection | recovery efficiency of the exhaust heat in the Stirling engine 1a is suppressed.

  When a negative determination is made in step S1, the ECU 10 determines whether or not the current room temperature is changing toward the required value (step S2). Specifically, it is determined whether or not the current room temperature is changing toward the required value from a change in room temperature within a predetermined period. If the determination is affirmative, the ECU 10 executes the process of step S1 assuming that the air volume guided into the vehicle compartment is sufficient. Thereby, the fall of the collection | recovery efficiency of the waste heat in the Stirling engine 1a is suppressed.

  If the determination in step S3 is negative, the ECU 10 determines that the air volume guided into the passenger compartment is insufficient, and the ECU 10 stops increasing the air volume to the second radiator 94 (step S4). That is, the ECU 10 maintains the current opening of the air volume control valve V4. Next, the ECU 10 determines whether or not the rate of change of the passenger compartment temperature that changes toward the required value is equal to or less than a predetermined value (step S5). Specifically, it is determined whether or not the rate of change in room temperature within a predetermined period is less than or equal to a predetermined value. If the rate of change of the passenger compartment temperature exceeds a predetermined value, that is, if a negative determination is made in step S5, the ECU 10 executes the process of step S2 assuming that the air volume into the passenger compartment is secured.

  When the rate of change in the passenger compartment temperature is equal to or lower than the predetermined value, that is, when an affirmative determination is made in step S5, the ECU 10 reduces the air volume to the second radiator 94 or stops blowing (step S6). Specifically, the air flow control valve V4 is driven to close the radiator air passage 74, or the air flow control valve V4 completely closes the heat radiator air passage 74. Thereby, the influence on the temperature control in a vehicle interior can be suppressed.

  The above control is repeated and executed under predetermined conditions. Thus, ECU10 suppresses the bad influence to the temperature of a compartment, suppressing the fall of the recovery efficiency of exhaust heat in Stirling engine 1a.

  FIG. 5 is an explanatory diagram of the exhaust heat recovery system 100a according to the second embodiment. In addition, about the structure similar to the exhaust heat recovery system 100 of Example 1, the overlapping description is abbreviate | omitted by attaching | subjecting a similar code | symbol.

  As shown in FIG. 5, the radiator air passage 74a of the air passage 70a branches from the indoor air passage 72a and merges with the bypass passage 73a again. Further, the joining portion of the indoor air passage 72 a and the bypass passage 73 a is upstream of the first radiator 93. Thus, the air passage 70a does not guide the air blown by the blower fan 8 to the outside of the vehicle. For this reason, the fall of the airflow to a compartment can be suppressed.

  For example, when the air conditioner AC is driven over the exhaust heat recovery efficiency of the Stirling engine 1a and priority is given to lowering the passenger compartment temperature, the air flow control valve V4 closes the radiator air passage 74a and the temperature adjustment valve V2. To close the bypass passage 73a. Thereby, the air from the blower fan 8 can guide only the air that has passed through the evaporator 81 and is cooled into the passenger compartment.

  When raising the room temperature, the air flow control valve V4 fully opens the radiator air passage 74a and the temperature adjustment valve V2 closes the indoor air passage 72a, so that the blower fan 8 changes to the indoor air passage 72a. The flowing air passes through the first radiator 93 and is guided into the vehicle interior. The air flowing from the blower fan 8 to the radiator air passage 74a passes through the second radiator 94 and is warmed, and further passes through the first radiator 93 to be warmed and guided into the vehicle interior. Thus, the air flowing through the radiator air passage 74a is warmed at the two locations of the second radiator 94 and the first radiator 93, and the vehicle compartment temperature can be effectively increased. Moreover, since the refrigerant | coolant which passes the cooler 45 of the Stirling engine 1a can be cooled as mentioned above, the fall of the collection | recovery efficiency of the exhaust heat of the heat engine 1 can be suppressed.

  As described above, when the vehicle interior is warmed, the vehicle interior can be effectively warmed while suppressing a reduction in the exhaust heat recovery efficiency in the Stirling engine 1a.

  FIG. 6 is an explanatory diagram of the exhaust heat recovery system 100b according to the third embodiment. In addition, about the structure similar to the exhaust heat recovery system 100 of Example 1, the overlapping description is abbreviate | omitted by attaching | subjecting a similar code | symbol.

  As shown in FIG. 6, the air passage 70b has an indoor air passage 72b, and unlike the first embodiment, the air passage 70b is not configured to blow air outside the vehicle. For this reason, all the airflows from the blower fan 8 are guided into the passenger compartment. The cooler 45 of the Stirling engine 1a is connected to the cycle of the air conditioner AC. That is, the refrigerant used in the air conditioner AC and the refrigerant flowing through the cooler 45 of the Stirling engine 1a are commonly used.

  FIG. 7 is an explanatory diagram of a refrigerant path circulating between the air conditioner AC and the Stirling engine 1a. As shown in FIG. 7, the air conditioner AC is provided with an evaporator 81, a compressor 82, a condenser 83, and an expansion valve 84. A refrigerant circulates between the evaporator 81 and the expansion valve 84. The compressor 82 compresses the refrigerant to high temperature and high pressure by the driving force transmitted from the heat engine 1 through the belt. The refrigerant that has reached high temperature and pressure is sent to the condenser 83. The condenser 83 cools the refrigerant by exchanging heat between the refrigerant and the outside air. The refrigerant is gas-liquid separated by a gas-liquid separator (not shown), and only the liquid-phase refrigerant is sent to the expansion valve 84. In the expansion valve 84, the refrigerant is decompressed and expanded. The refrigerant expanded under reduced pressure is sent to the evaporator 81. In the evaporator 81, the refrigerant expanded under reduced pressure is vaporized, and the air is cooled by the latent heat of evaporation.

  Further, the refrigerant circulates between the cooler 45 and the air conditioner AC through the refrigerant passage W20. Specifically, a part of the refrigerant flows from the upstream side of the evaporator 81 to the cooler 45. The refrigerant that has passed through the cooler 45 returns to the downstream side of the evaporator 81. Thus, it can be considered that the cooler 45 and the evaporator 81 are connected in parallel. A valve V5 is provided on the refrigerant passage W20, and the flow rate of the refrigerant passing through the cooler 45 of the Stirling engine 1a can be adjusted by the ECU 10 controlling the opening degree of the valve V5.

  Thus, the refrigerant passing through the cooler 45 of the Stirling engine 1a can be dissipated using the evaporator 81 of the air conditioner AC. Thereby, the structure of the whole waste heat recovery system 100b can be simplified. Moreover, since the refrigerant | coolant which passes the cooler 45 can be cooled, even if it is a case where the temperature of the exhaust gas from the heat engine 1 is low as mentioned above, the fall of the recovery efficiency of exhaust heat can be suppressed.

  Further, since the air passage 70b does not guide the air to the outside of the vehicle, all the airflow from the blower fan 8 can be guided to the passenger compartment, and the airflow guided into the passenger compartment can be ensured.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

DESCRIPTION OF SYMBOLS 1 Heat engine 1a Stirling engine 3 Exhaust pipe 45 Cooler 70 Air supply path 72, 72a, 72b Indoor air supply path 73, 73a, 73b Bypass path 74, 74a Radiator air supply path 81 Evaporator 94 2nd heat sinks 100, 100a, 100b Waste heat recovery system V3 Temperature control valve V4 Air flow control valve W10, W20 Refrigerant passage

Claims (4)

A Stirling engine having a cooler for cooling the working fluid that receives heat from the exhaust gas of the heat engine;
A radiator that is connected to the cooler through a passage through which the refrigerant passes and in which the refrigerant circulates between the cooler,
An exhaust heat recovery system comprising: a radiator air passage that guides air to a radiator of a fan for sending air into a room of a vehicle on which the heat engine is mounted. An indoor air passage that is connected to the radiator air passage and guides the air from the fan into the room;
The exhaust heat recovery system of Claim 1 provided with the control valve which opens and closes the said ventilation passage for heat radiators of the upstream from the said heat radiator. An indoor radiator that is disposed in the indoor air passage and through which a refrigerant for cooling the heat engine passes;
The exhaust heat recovery system according to claim 1 or 2, wherein the air blower passage for the radiator guides the air that has passed through the radiator to the radiator for the room. A Stirling engine having a cooler for cooling the working fluid that receives heat from the exhaust gas of the heat engine;
An exhaust heat recovery system comprising: an evaporator of an air conditioner that is connected to the cooler through a passage through which a refrigerant passes and that cools the interior of a vehicle on which the heat engine is mounted.

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