JP2010188949A - Vehicle having waste heat recovery system mounted thereon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of a waste heat recovery system in terms of control of a motor fan in a vehicle mounting the waste heat recovery system for recovering waste heat of an engine. <P>SOLUTION: The vehicle having the waste heat recovery system mounted thereon includes: the engine 1; a cooling water circuit 10 including a radiator 12 for releasing the heat of the cooling water of the engine 1 to open air, through which the cooling water is circulated between the engine 1 and the radiator 12; a Rankine cycle 20 including a heater 22 for heating coolant by recovering the heat of the cooling water; an expander 23 for outputting power by expanding the heated coolant, and a Rankine condenser 24 for condensing the coolant by releasing the heat of the expanded coolant to the open air; a first fan 2 for sending air to the Rankine radiator 24; a second fan 3 for sending air to the radiator 24; and a fan control means 4 for controlling operations of the first fan 2 and the second fan 3. The fan control means 4 activates only the first fan 2 when the temperature of the cooling water is lower than a predetermined temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to control of a motor fan in a vehicle equipped with a waste heat recovery system that recovers waste heat of an engine.

  Patent Document 1 describes that in a vehicle, a radiator that cools cooling water for an engine and a condenser that cools refrigerant for an air conditioner are cooled by a common motor fan. Furthermore, it is described that the deterioration of fuel consumption performance due to excessive cooling of the radiator and condenser is prevented by switching and controlling the operation or stop of the motor fan based on the vehicle speed, the coolant temperature of the engine, and the pressure of the refrigerant for the air conditioner. Yes.

  Patent Document 2 describes a waste heat recovery system that recovers engine waste heat using a Rankine cycle. In the waste heat recovery system, the refrigerant is heated by exchanging heat with the engine coolant in the heater, and the high-pressure refrigerant is adiabatically expanded in the expander to recover power. The expanded refrigerant is cooled by a motor fan in the condenser and sent to the heater again.

Japanese Patent Laid-Open No. 2003-204686 JP-A-2004-232492

  However, when the motor fan control as described in Patent Document 1 is applied to a vehicle equipped with a waste heat recovery system as described in Patent Document 2, when the engine coolant temperature rises, When activated, heat dissipation from the radiator is promoted, and the cooling water temperature of the engine is lowered. Since the heat energy that can be recovered in the heater is reduced due to the decrease in the cooling water temperature, the mechanical energy that can be extracted as power in the expander is reduced, and the efficiency of the waste heat recovery system is reduced.

  An object of the present invention is to improve the efficiency of a waste heat recovery system.

  The present invention includes an engine, a radiator that discharges heat of engine cooling water to the outside air, a cooling water circuit in which the cooling water circulates between the engine and the radiator, and recovers heat of the cooling water to generate a refrigerant. A Rankine cycle having a heater that heats, an expander that outputs power by expanding the heated refrigerant, and a Rankine condenser that releases the heat of the expanded refrigerant to the outside air to condense the refrigerant; In a vehicle equipped with a waste heat recovery system, comprising: a first fan that blows air to a Rankine condenser; a second fan that blows air to a radiator; and a fan control means that controls the operation of the first fan and the second fan. The fan control means operates only the first fan when the temperature of the cooling water is lower than a predetermined temperature.

  According to the present invention, when the cooling water temperature of the engine is lower than the predetermined temperature, only the first fan that blows air to the Rankine condenser is operated, so that the amount of heat released from the radiator to the outside air is reduced as much as possible. can do. As a result, the amount of heat that can be recovered by the Rankine cycle can be increased and more power can be output, so that the efficiency of the waste heat recovery system can be improved.

It is a schematic block diagram which shows the structure of the waste heat recovery system mounting vehicle in this embodiment. It is a schematic block diagram which shows control of the vehicle with a waste heat recovery system in this embodiment. It is a schematic block diagram which shows control of the vehicle with a waste heat recovery system in this embodiment. It is a map which shows the relationship between a motor fan operation | movement engine cooling water temperature and external temperature. It is a map which shows the relationship between the vehicle speed in this embodiment, the refrigerant | coolant pressure of an air-conditioner cycle, cooling water temperature, and the output of a motor fan. It is a map which shows the relationship between the vehicle speed in a prior art example, the refrigerant pressure of an air-conditioner cycle, cooling water temperature, and the output of a motor fan.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a configuration of a vehicle equipped with a waste heat recovery system in the present embodiment. The vehicle equipped with the waste heat recovery system in the present embodiment cools the cooling water circuit 10 that cools the engine 1, the Rankine cycle 20 that recovers the waste heat of the engine 1 from the cooling water, and the conditioned air supplied to the vehicle interior. The air conditioner cycle 30 includes a first motor fan 2 (first fan), a second motor fan 3 (second fan), and a controller 4 (fan control means).

  The cooling water circuit 10 will be described.

  The cooling water circuit 10 includes a water pump 11, a radiator 12, a bypass passage 13, and a thermostat 14, and the circuit is filled with cooling water (antifreeze).

  The water pump 11 is driven by the engine 1 to circulate cooling water in the circuit. The water pump 11 may be driven by an electric motor. The radiator 12 performs heat exchange between the cooling water and the outside air, and radiates the heat of the cooling water to the outside. The bypass passage 13 is connected to the inlet side and the outlet side of the radiator 12, and is a flow path through which cooling water flows so as to bypass the radiator 12. The thermostat 14 is a valve that is provided on the inlet side of the bypass passage 13 and opens and closes depending on the temperature of the cooling water. That is, when the cooling water temperature is high, the valve is opened to allow the cooling water to flow to the radiator 12, and when the cooling water temperature is low, the valve is closed to allow the cooling water to flow to the bypass passage 13.

  The Rankine cycle 20 will be described.

  The Rankine cycle 20 includes a pump 21, a heater 22, an expander 23, a condenser 24 (hereinafter referred to as “Rankine condenser”), and a gas-liquid separator 25. The circuit is filled with Rankine refrigerant.

  The pump 21 pressurizes the liquid-phase refrigerant and pumps it to the heater 22. In the heater 22, heat exchange is performed between the refrigerant and the cooling water in the cooling water circuit 10, and the liquid refrigerant is heated to become a gas. The gaseous refrigerant is pumped to the expander 23. The expander 23 adiabatically expands the pressure-fitted refrigerant to convert the heat energy of the refrigerant into mechanical energy and recover power. The refrigerant expanded in the expander 23 is sent to the condenser 24. The condenser 24 cools and liquefies the refrigerant by exchanging heat between the refrigerant and the outside air. The liquefied refrigerant is gas-liquid separated in the gas-liquid separator 25, and only the liquid-phase refrigerant is sent to the pump 21.

  The air conditioner cycle 30 will be described.

  The air conditioner cycle 30 includes a compressor 31, a condenser 32 (hereinafter referred to as “air conditioner condenser”), a gas-liquid separator 33, an expansion valve 34, and an evaporator 35, and air conditioner refrigerant circulates in the circuit.

  The compressor 31 is driven by a driving force transmitted from the engine 1 via a belt, and compresses the gas-phase refrigerant to a high temperature and a high pressure. The high-temperature and high-pressure refrigerant is sent to the condenser 32. The compressor 31 may be driven by an electric motor instead of the engine 1. The condenser 32 cools and liquefies the refrigerant by exchanging heat between the refrigerant and the outside air. The liquefied refrigerant is gas-liquid separated by the gas-liquid separator 33, and only the liquid-phase refrigerant is sent to the expansion valve 34. In the expansion valve 34, the liquid-phase refrigerant is decompressed and expanded, and the decompressed and expanded refrigerant is sent to the evaporator 35. In the evaporator 35, the refrigerant expanded under reduced pressure is vaporized, and the conditioned air passing through the evaporator 35 is cooled by the latent heat of evaporation. The vaporized refrigerant is sent to the compressor 31.

  The first motor fan 2 and the second motor fan 3 will be described.

  The first motor fan 2 is provided in the vicinity of the Rankine condenser 24 and the air conditioner condenser 32, and heat is radiated from the refrigerant in each condenser 24, 32 by blowing outside air to each condenser 24, 32. To promote. The second motor fan 3 is provided in the vicinity of the radiator 12 and promotes heat dissipation from the cooling water in the radiator 12 by blowing outside air to the radiator 12. In other words, the motor fan 2 for the radiator is provided independently of the motor fan 3 for the Rankine cycle and the air conditioner cycle.

  The controller 4 includes a vehicle speed sensor 5 that detects the vehicle speed V, a cooling water temperature sensor 6 that detects the cooling water temperature Tw of the engine 1, an outside air temperature sensor 7 that detects the outside air temperature To, and an air conditioner operating state detection that detects the operating state of the air conditioner. Each detection value is received from the sensor 8 and the refrigerant pressure sensor 9 for detecting the refrigerant pressure Pd of the air conditioner cycle, and the outputs of the first motor fan 2 and the second motor fan 3 are controlled. The first motor fan 2 and the second motor fan 3 are driven by power supplied from a battery (not shown), and the outputs of the first motor fan 2 and the second motor fan 3 are set to a duty ratio by a PWM driver, for example. Control by changing.

  Next, control of the first motor fan 2 and the second motor fan 3 by the controller 4 will be described with reference to FIGS. 2 and 3 are flowcharts showing the control of the vehicle equipped with the waste heat recovery system in the present embodiment, FIG. 2 shows the control of the first motor fan, and FIG. 3 shows the control of the second motor fan. . The first motor fan 2 and the second motor fan 3 are controlled independently, and both FIG. 2 and FIG. 3 are repeatedly executed every predetermined minute time (for example, 10 ms).

  First, the control of the first motor fan 2 will be described with reference to FIG.

  In step S11, the coolant temperature Tw, the outside air temperature To, the vehicle speed V, and the operating state of the air conditioner of the engine 1 are detected.

  In step S12, the operating coolant temperature TL, TM, TH (determination temperature) of the first motor fan 2 is set. The operating coolant temperatures TL, TM, and TH are threshold values used in step S15 described later for setting the output of the first motor fan 2, and are set according to the outside air temperature with reference to the map of FIG. . The operating cooling water temperatures TL, TM, and TH are set higher as the outside air temperature is higher. For example, if the outside air temperature is 15 ° C., the operating cooling water temperature is TL = 75 ° C., TM = 85 ° C., TH = 95 ° C. Is set.

  In step S13, it is determined whether or not the air conditioner is in an ON state. If the air conditioner is on, the process proceeds to step S14, and if it is off, the process proceeds to step S15.

  In step S14, the refrigerant pressure Pd of the air conditioner cycle is detected.

  In step S15, the output of the first motor fan 2 is set. The output of the first motor fan 2 is based on the coolant temperature Tw of the engine 1, the outside air temperature To, the vehicle speed V, the operating state of the air conditioner, and the refrigerant pressure Pd of the air conditioner cycle with reference to the map of FIG. Is set.

  The map of FIG. 5A shows the relationship between the coolant temperature Tw of the engine 1, the outside air temperature To, the vehicle speed V, the operating state of the air conditioner, the refrigerant pressure Pd of the air conditioner cycle, and the output of the first motor fan 2. The output of the first motor fan 2 is selected from four stages of OFF (stop), LOW (low air volume), MID (medium air volume), and HIGH (high air volume). Further, the values set in step S2 are inserted into the operating cooling water temperatures TL, TM, and TH.

  As shown in FIG. 5A, the vehicle speed V is divided into three regions of 0 to 20 km / h, 20 to 80 km / h, and 80 km / h or more, and the lower the vehicle speed V, the output of the first motor fan. Is set higher.

  Each speed region is divided into two regions of an air conditioner stop state and an operation state, and the region where the air conditioner is in an operation state is Pd <A, A ≦ Pd <B, B ≦ Pd depending on the refrigerant pressure Pd. <C, C ≦ Pd. The output of the first motor fan 2 is set so that the air conditioner is higher in the operating state than in the stopped state, and is set higher as the refrigerant pressure Pd is higher.

  Further, according to the cooling water temperature Tw, it is divided into four regions of Tw <TL, TL ≦ Tw <TM, TM ≦ Tw <TH, TH ≦ Tw, and the output of the first motor fan 2 is the cooling water temperature Tw. The higher the value, the higher the value.

  Here, since the operating cooling water temperatures TL, TM, and TH are set to be lower as the outside air temperature To is lower, the output of the first motor fan 2 is set to be higher as the outside air temperature To is lower. The As a result, the lower the outside air temperature To, the more the first motor fan 2 operates from a state where the cooling water temperature Tw is lower.

  Returning to FIG. 2, in step S16, the output of the first motor fan 2 is controlled based on the output set in step S15.

  Next, the control of the second motor fan 3 will be described with reference to FIG.

  In step S21, the coolant temperature Tw of the engine 1 is detected.

  In step S22, the output of the second motor fan 3 is set. The output of the second motor fan 3 is set based on the coolant temperature Tw of the engine 1 with reference to the map of FIG.

  The map of FIG. 5B shows the relationship between the coolant temperature Tw of the engine 1 and the second motor fan 3, and the output of the second motor fan 3 is OFF (stop) and HIGH (high air flow). Are selected from the following two stages.

  As shown in FIG. 5 (b), the output of the second motor fan 3 changes only according to the cooling water temperature Tw of the engine 1, and is set to HIGH when the cooling water temperature Tw is 105 ° C. or higher, and below 105 ° C. Set to OFF. That is, the second motor fan 3 is always stopped until the cooling water temperature Tw reaches 105 ° C.

  Returning to FIG. 3, in step S23, the output of the second motor fan 3 is controlled based on the output set in step S22.

  Hereinafter, the operation of the present embodiment will be described in comparison with a conventional example.

  Conventionally, an air conditioner condenser is provided in the vicinity of a radiator, and the radiator and the air conditioner condenser are cooled by a motor fan. In such a configuration, the output of the motor fan is controlled, for example, as shown in the map of FIG. That is, since the air conditioner condenser needs to be cooled when the air conditioner is in an operating state, the output of the motor fan is controlled according to the refrigerant pressure Pd of the air conditioner cycle.

  When the motor fan is operated, the radiator is also cooled at the same time, so that the heat of the engine coolant is released and the coolant temperature Tw is lowered. Therefore, when the Rankine cycle is applied to such a conventional configuration, the amount of heat that can be recovered by the Rankine cycle decreases.

  On the other hand, in the present embodiment, the Rankine condenser 24 and the air conditioner condenser 32 are cooled by the first motor fan 2, and the radiator 12 is cooled by the second motor fan 3. The motor fan 2 is controlled so that the higher the cooling water temperature Tw of the engine 1 is, the higher the output is. The second motor fan 3 is in the operating state when the cooling water temperature Tw of the engine 1 is lower than 105 ° C. Control to stop regardless.

  As a result, the region where the second motor fan 3 that cools the radiator 12 is stopped (the region in the OFF state in FIG. 5B) is enlarged, so that the amount of heat released from the radiator 12 can be reduced. . In addition, the first motor fan 2 cools the Rankine cycle condenser 24 by cooling the Rankine condenser 24, and accordingly, the Rankine cycle 20 refrigerant generates more waste heat from the cooling water of the engine 1. And the cooling water of the engine 1 is indirectly cooled. Therefore, more waste heat can be recovered in the Rankine cycle 20 as much as the amount of heat released from the radiator 12 is reduced.

  As described above, in the present embodiment, when the coolant temperature Tw of the engine 1 is lower than 105 ° C., only the first motor fan 2 that blows the outside air to the Rankine condenser 24 is operated. The amount of heat released into the can is reduced as much as possible, and the amount of heat that can be recovered by the Rankine cycle 20 can be increased accordingly. Therefore, since more power can be output in the expander 23, the efficiency of the waste heat recovery system can be improved.

  Further, in the case where the cooling capacity of the cooling water is insufficient only by the waste heat recovery by the Rankine cycle 20, when the cooling water temperature Tw rises to 105 ° C. or higher, the second motor fan in addition to the first motor fan 2 3 is also operated, so that an excessive increase in the cooling water temperature Tw can be suppressed while improving the efficiency of waste heat recovery.

  Further, the air volume (output) of the first motor fan 2 is higher as the cooling water temperature Tw of the engine 1 is higher due to the magnitude relationship between the cooling water temperature Tw of the engine 1 and the motor fan operating cooling water temperatures TL, TM, and TH. Since the operating cooling water temperatures TL, TM, and TH are set to be lower as the outside air temperature To is lower, the temperature between the outside air temperature To and the cooling water temperature Tw is low even when the outside air temperature To is low. A difference can be ensured and waste heat recovery can be performed, and the efficiency of the waste heat recovery system can be further improved.

  Further, the first motor fan 2 is arranged to blow outside air to the Rankine condenser 24 and the air conditioner condenser 32, and the second motor fan 3 is arranged to blow outside air to the radiator 12. The second motor fan 3 can be stopped until the coolant temperature Tw of the engine 1 reaches 105 ° C. regardless of the operating state of the air conditioner, and the amount of heat released from the radiator 12 to the outside air is reduced as much as possible. Thus, the efficiency of the waste heat recovery system can be improved.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea.

DESCRIPTION OF SYMBOLS 1 Engine 2 1st motor fan 3 2nd motor fan 4 Controller 10 Cooling water circuit 12 Radiator 20 Rankine cycle 22 Heater 23 Expander 24 Rankine condenser 30 Air conditioner cycle 31 Compressor 32 Air conditioner condenser 35 Evaporator

Claims (4)

Engine,
A radiator that discharges heat of cooling water of the engine to the outside air, and a cooling water circuit in which the cooling water circulates between the engine and the radiator;
A heater that recovers heat of the cooling water to heat the refrigerant, an expander that outputs power by expanding the heated refrigerant, and releases the heat of the expanded refrigerant to the outside air. A Rankine cycle having a Rankine condenser for condensing
A first fan that blows air to the Rankine condenser;
A second fan for blowing air to the radiator;
Fan control means for controlling the operation of the first fan and the second fan;
In vehicles equipped with a waste heat recovery system,
The waste heat recovery system-equipped vehicle, wherein the fan control means activates only the first fan when the temperature of the cooling water is lower than a predetermined temperature.   2. The waste heat according to claim 1, wherein the fan control unit operates the second fan in addition to the first fan when the temperature of the cooling water becomes equal to or higher than the predetermined temperature. Vehicle with collection system. When the fan control means is controlling the air volume of the first fan to be the first air volume, the temperature of the cooling water is equal to or higher than a predetermined determination temperature lower than the predetermined temperature. , Controlling the air volume of the first fan to be a second air volume larger than the first air volume,
The vehicle with a waste heat recovery system according to claim 1 or 2, wherein the predetermined determination temperature is set to be lower as the outside air temperature is lower. A compressor that compresses the air-conditioner refrigerant, an air-conditioner condenser that releases the heat of the compressed air-conditioner refrigerant to the outside air to cool and liquefy the air-conditioner refrigerant, and vaporizes the liquefied air-conditioner refrigerant An air conditioner cycle having an evaporator for cooling the conditioned air introduced into the passenger compartment,
The first fan, the second fan, the Rankine condenser, the air conditioner condenser, and the radiator, the first fan sends air to the Rankine condenser and the air conditioner condenser, The vehicle with a waste heat recovery system according to any one of claims 1 to 3, wherein the second fan is arranged so as to blow air to the radiator.