WO2014010465A1 - Rankine cycle device - Google Patents

Rankine cycle device Download PDF

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Publication number
WO2014010465A1
WO2014010465A1 PCT/JP2013/068105 JP2013068105W WO2014010465A1 WO 2014010465 A1 WO2014010465 A1 WO 2014010465A1 JP 2013068105 W JP2013068105 W JP 2013068105W WO 2014010465 A1 WO2014010465 A1 WO 2014010465A1
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WIPO (PCT)
Prior art keywords
pressure
working fluid
expander
pump
side pressure
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PCT/JP2013/068105
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French (fr)
Japanese (ja)
Inventor
耕二郎 田丸
井口　雅夫
英文 森
榎島　史修
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株式会社 豊田自動織機
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Publication of WO2014010465A1 publication Critical patent/WO2014010465A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
    • F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G5/00—Profiting from waste heat of combustion engines, not otherwise provided for
    • F02G5/02—Profiting from waste heat of exhaust gases
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Definitions

  • the present invention relates to a Rankine cycle device.
  • the Rankine cycle device includes a pump that pumps the working fluid, a heat exchanger that exchanges heat with the fluid from the exhaust heat source, and a working fluid that is heat-exchanged by the heat exchanger. And an expander that outputs dynamic energy and a condenser that condenses the working fluid expanded by the expander.
  • a pump, a heat exchanger, an expander, and a condenser are sequentially connected to form a working fluid circuit in which the working fluid circulates.
  • the pressure of the working fluid flowing from the outlet of the pump to the inlet of the expander is “high pressure side pressure (evaporation pressure)”, and the pressure of the working fluid flowing from the outlet of the expander to the inlet of the pump is The “low pressure side pressure (condensation pressure)” is lower than the high pressure side pressure.
  • Patent Document 1 a pressure difference detection device that detects a difference between a high-pressure side pressure and a low-pressure side pressure of the working fluid flowing in the working fluid circuit, and a pressure difference detected by the pressure difference detection device are determined in advance.
  • a Rankine cycle device is disclosed that includes a pressure difference increasing device that increases a pressure difference so as to be a predetermined pressure difference when the pressure difference falls below a predetermined pressure difference.
  • Patent Document 2 discloses that control is performed such that the difference between the high-pressure side pressure and the low-pressure side pressure of the working fluid flowing in the working fluid circuit is kept constant. According to these, the difference between the high-pressure side pressure and the low-pressure side pressure is prevented from becoming too small, and the expander can output stable mechanical energy.
  • the difference between the evaporation pressure and the condensation pressure is controlled to be kept constant. For this reason, for example, when the condensing pressure is lowered, the evaporation pressure is lowered even when the pressure difference is in a range where the reliability of the expander and the pump is maintained. That is, the difference between the evaporation pressure and the condensation pressure cannot be made larger than a certain value, and as a result, the mechanical energy output from the expander cannot be made as large as possible.
  • An object of the present disclosure is to provide a Rankine cycle device that can ensure the reliability of the expander and the pump and can increase the mechanical energy output from the expander as much as possible.
  • the Rankine cycle device for achieving the above object includes a pump that pumps a working fluid, a heat exchanger that exchanges heat between the working fluid pumped by the pump and a fluid from an exhaust heat source, and heat exchange using the heat exchanger.
  • An expander that expands the generated working fluid to output mechanical energy, and a condenser that condenses the working fluid expanded by the expander, the pump, the heat exchanger, the expander, and the The condenser is connected in series to form a working fluid circuit through which the working fluid circulates, and a low pressure side pressure that is a pressure of the working fluid flowing from the outlet of the expander to the inlet of the pump.
  • a pressure control device that controls a high-pressure side pressure that is a pressure of a working fluid that flows from the outlet of the pump to the inlet of the expander.
  • the pressure control device keeps the high-pressure side pressure constant even when the low-pressure side pressure is reduced, as long as the difference between the high-pressure side pressure and the low-pressure side pressure does not exceed a preset control upper limit value. Configured to control.
  • the schematic diagram which shows the Rankine cycle apparatus in embodiment The graph which shows the change of a high pressure side pressure and a low pressure side pressure. The graph which shows the change of the high voltage
  • FIGS. 1 and 2 a Rankine cycle device mounted on a vehicle according to an embodiment will be described with reference to FIGS. 1 and 2.
  • the Rankine cycle device 10 includes a working fluid circuit 11 through which a working fluid circulates.
  • the working fluid circuit 11 includes an expander 20, a condenser 30, a pump 40, and a heat exchanger 50 that are sequentially connected.
  • the working fluid flows along the arrangement order of the expander 20, the condenser 30, the pump 40, and the heat exchanger 50 and circulates in the working fluid circuit 11.
  • the heat exchanger 50 includes a heat absorber 50a and a heat radiator 50b.
  • the heat absorber 50 a is connected to the outlet of the pump 40 through the first passage 21.
  • the radiator 50b is provided around the exhaust passage E1 connected to the engine E as an exhaust heat source. The exhaust of the engine E is exhausted from the muffler E2 after being radiated by the radiator 50b.
  • the heat absorber 50 a of the heat exchanger 50 and the inlet of the expander 20 are connected via the second passage 22.
  • the outlet of the expander 20 and the inlet of the condenser 30 are connected via a third passage 23.
  • the outlet of the condenser 30 and the inlet of the pump 40 are connected via the fourth passage 24.
  • the heat exchanger 50 changes the working fluid in a low-temperature and high-pressure liquid state pumped by the pump 40 into a high-temperature and high-pressure working fluid by exchanging heat with the exhaust flowing through the exhaust passage E1 of the engine E.
  • the condenser 30 changes the working fluid that has been expanded in the expander 20 and turned into a high-temperature and low-pressure gas state into a low-temperature and low-pressure liquid-state working fluid by exchanging heat with the outside air.
  • Rankine cycle device 10 includes a drive shaft 60 a that functions as both a pump shaft of pump 40 and an output shaft of expander 20.
  • a pulley 60b is fixed to the end of the drive shaft 60a.
  • a belt 60c is wound around the pulley 60b.
  • the belt 60c is wound around a pulley E4 fixed to a crankshaft E3 that is a rotation output shaft of the engine E.
  • the crankshaft E3 is connected to the drive shaft 60a via a pulley E4, a belt 60c, and a pulley 60b.
  • the working fluid circuit 11 has one end connected to the first passage 21 (that is, a passage extending between the outlet of the pump 40 and the heat exchanger 50) and the other end connected to the third passage 23 (that is, the expander 20).
  • a bypass passage 71 connected to an outlet of the condenser 30 and an inlet of the condenser 30.
  • the bypass passage 71 is provided with a flow rate adjusting valve 71a that changes the flow rate of the working fluid flowing from the pump 40 to the bypass passage 71 and the heat exchanger 50, respectively.
  • the flow rate adjustment valve 71 a is connected to the control unit 75.
  • the control unit 75 transmits a signal to the flow rate adjusting valve 71a in order to adjust the opening degree of the flow rate adjusting valve 71a.
  • pressure detection for detecting a low-pressure side pressure (condensation pressure) that is the pressure of the working fluid that has passed through the condenser 30.
  • a first pressure sensor 72 as a device is provided.
  • the first pressure sensor 72 is connected to the control unit 75 so that a signal can be transmitted to the control unit 75.
  • the first pressure sensor 72 sends a signal indicating the detection result to the control unit 75.
  • a high-pressure side pressure that is the pressure of the working fluid that has passed through the heat exchanger 50 is detected.
  • a second pressure sensor 73 is provided. The second pressure sensor 73 is connected to the control unit 75 so that signals can be transmitted to the control unit 75. The second pressure sensor 73 sends a signal indicating the detection result to the control unit 75.
  • the working fluid When the pump 40 is driven, the working fluid is pumped by the pump 40 and circulates in the working fluid circuit 11.
  • the working fluid sent from the pump 40 to the heat exchanger 50 through the first passage 21 passes through the heat exchanger 50, it is heat-exchanged with the exhaust gas and becomes a high-temperature and high-pressure gas state.
  • the working fluid that has passed through the heat exchanger 50 and is in a high-temperature and high-pressure gas state is sucked into the expander 20 from the inlet of the expander 20 via the second passage 22.
  • the working fluid sucked into the expander 20 is expanded by the expander 20, and part of the thermal energy of the working fluid is taken out as mechanical energy through the expander 20 to assist the rotational output of the engine E. Used for.
  • the working fluid whose temperature has been lowered and reduced in pressure in the expander 20 is sucked into the condenser 30 from the outlet of the expander 20 via the third passage 23.
  • the working fluid sucked into the condenser 30 is condensed and liquefied by the condenser 30, and is returned to the pump 40 through the fourth passage 24.
  • the pressure detected by the first pressure sensor 72 is greatly affected by the temperature of the outside air that exchanges heat with the working fluid in the condenser 30.
  • the higher the temperature of the outside air the harder the working fluid is cooled (condensed) in the condenser 30 and the lower the pressure of the working fluid.
  • the lower the temperature of the outside air the easier the working fluid is cooled (condensed) in the condenser 30 and the pressure of the working fluid tends to be low.
  • FIG. 2 shows changes in pressure (changes in low-pressure side pressure and high-pressure side pressure) detected by the first pressure sensor 72 and the second pressure sensor 73, respectively.
  • the pressure difference Z1 between the pressure P11 detected by the first pressure sensor 72 and the pressure P21 detected by the second pressure sensor 73 is constant, and a preset control is performed. It is smaller than the upper limit.
  • the “control upper limit value Z” is the high pressure side pressure and the low pressure side pressure at which the expander 20 and the pump 40 do not impair the reliability of the equipment due to the load received by the difference between the high pressure side pressure and the low pressure side pressure. This is the upper limit of the difference.
  • the temperature of the outside air gradually decreases from time T1 to time T2 from time T2 to time T3. Then, the working fluid is cooled to a temperature lower than the temperature at the time T1 to the time T2 in the condenser 30 from the time T2 to the time T3, and the pressure of the working fluid gradually decreases.
  • the pressure P12 detected by the first pressure sensor 72 at time T3 is lower than the pressure P11 detected by the first pressure sensor 72 at time T2.
  • the control unit 75 determines that the flow rate of the working fluid flowing from the first passage 21 through the bypass passage 71 to the third passage 23 is within a range where the difference between the high pressure side pressure and the low pressure side pressure does not exceed the control upper limit value.
  • the opening degree of the flow rate adjustment valve 71a is controlled so as to decrease.
  • the control unit 75 functions as a pressure control device that controls the high-pressure side pressure.
  • the pressure difference Z2 between the pressure P12 detected by the first pressure sensor 72 and the pressure P21 detected by the second pressure sensor 73 is constant. It is assumed that the temperature of the outside air further gradually decreases from the time T3 to the time T4 between the time T4 and the time T5. Then, the working fluid is cooled to a temperature further lower than the temperature between time T3 and time T4 in the condenser 30 between time T4 and time T5, and the pressure of the working fluid gradually decreases. Go.
  • the pressure P13 detected by the first pressure sensor 72 at time T5 is lower than the pressure P12 detected by the first pressure sensor 72 at time T4.
  • the controller 75 controls the opening degree of the flow rate adjusting valve 71a so that the flow rate of the working fluid flowing from the first passage 21 through the bypass passage 71 to the third passage 23 increases.
  • the flow rate of the working fluid flowing from the outlet of the pump 40 to the inlet of the expander 20 decreases, and the pressure P22 detected by the second pressure sensor 73 at time T5 is the second pressure at time T4. It becomes lower than the pressure P21 detected by the sensor 73.
  • the pressure difference Z3 between the pressure P13 detected by the first pressure sensor 72 and the pressure P22 detected by the second pressure sensor 73 is a preset control upper limit value. That is, the flow rate adjustment is performed so that the pressure difference Z3 between the pressure P13 and the pressure P22 becomes the control upper limit value by changing the flow rate of the working fluid flowing from the first passage 21 to the third passage 23 via the bypass passage 71.
  • the opening degree of the valve 71 a is adjusted by the control unit 75.
  • the high pressure side pressure decreases from time T4 to time T5 so that the difference between the high pressure side pressure and the low pressure side pressure does not exceed the control upper limit value, so the difference between the high pressure side pressure and the low pressure side pressure. Is prevented from becoming too large.
  • the Rankine cycle apparatus 10 includes a first pressure sensor 72 that detects a low-pressure side pressure that is a pressure of a working fluid that flows from the outlet of the expander 20 to the inlet of the pump 40.
  • the bypass passage 71 having one end connected to the first passage 21 and the other end connected to the third passage 23 is disposed, and the operation flows through the bypass passage 71 through the bypass passage 71.
  • a flow rate adjusting valve 71a for changing the flow rate of the fluid and the flow rate of the working fluid flowing through the heat exchanger 50 is provided.
  • control part 75 changes the flow volume of the working fluid which flows into the 3rd channel
  • the high-pressure side pressure that is the pressure is controlled.
  • the control unit 75 causes the difference between the high-pressure side pressure and the low-pressure side pressure to exceed a preset control upper limit value.
  • the flow rate of the working fluid flowing from the first passage 21 through the bypass passage 71 to the third passage 23 is decreased. Therefore, the high-pressure side pressure can be controlled so that the high-pressure side pressure is maintained at a constant value without gradually decreasing following the low-pressure side pressure.
  • the difference between the high pressure side pressure and the low pressure side pressure can be increased as much as possible within a range not exceeding the control upper limit value.
  • the low-pressure side pressure detected by the first pressure sensor 72 when the low-pressure side pressure detected by the first pressure sensor 72 is excessively low, the amount of working fluid flowing from the first passage 21 to the third passage 23 through the bypass passage 71 is increased. Thus, the flow rate of the working fluid flowing from the outlet of the pump 40 to the inlet of the expander 20 can be reduced. As a result, the high pressure side pressure can be lowered so that the difference between the high pressure side pressure and the low pressure side pressure does not exceed the control upper limit value, so the difference between the high pressure side pressure and the low pressure side pressure becomes too large. This can be prevented. As a result, the reliability of the expander 20 and the pump 40 can be ensured, and the mechanical energy output from the expander 20 can be maximized.
  • the high pressure side pressure is controlled by changing the flow rate of the working fluid flowing from the first passage 21 to the third passage 23 through the bypass passage 71. Therefore, for example, in order to control the high-pressure side pressure, there is no need to control the rotation speed of the motor that drives the pump 40 or the rotation speed of the expander 20, and the single drive shaft 60a can be controlled. It becomes possible to function as both the pump shaft of the pump 40 and the expander 20, and the configuration of the Rankine cycle apparatus 10 can be simplified.
  • an upper limit value of the high pressure side pressure may be set in advance.
  • the pressure difference Z4 between the pressure P14 detected by the first pressure sensor 72 and the pressure P23 detected by the second pressure sensor 73 is constant between time T6 and time T7. It is. At this time, it is assumed that the pressure P23 detected by the second pressure sensor 73 has already reached the upper limit value of the high-pressure side pressure. Then, it is assumed that the temperature of the outside air gradually rises from time T6 to time T7 from time T7 to time T8.
  • the working fluid is condensed to a temperature higher than that at the time T6 to the time T7 in the condenser 30 from the time T7 to the time T8, and the pressure of the working fluid is gradually increased.
  • the pressure P15 detected by the first pressure sensor 72 at time T8 is higher than the pressure P14 detected by the first pressure sensor 72 at time T7, and the high pressure side pressure and the low pressure side pressure are detected. The difference with is small.
  • the control unit 75 controls the high pressure side pressure so that the high pressure side pressure does not exceed the upper limit value.
  • control unit 75 controls the rotational speed of the motor that drives the pump 40, thereby changing the flow rate of the working fluid pumped from the pump 40 to the heat exchanger 50, and the high-pressure side pressure reaches the upper limit value. Do not exceed. According to this, a situation in which the high pressure side pressure becomes excessively high due to an attempt to increase the difference between the high pressure side pressure and the low pressure side pressure as much as possible within a range not exceeding the control upper limit value. Can be prevented. As a result, the reliability of the expander 20 and the pump 40 can be further ensured.
  • the drive shaft 60a may not function as both the pump shaft of the pump 40 and the output shaft of the expander 20.
  • the Rankine cycle apparatus 10 may include a motor 40 a that drives the pump 40.
  • a pulley 201b is fixed to the output shaft 20b of the expander 20.
  • a belt 60c is wound around the pulley 201b.
  • the belt 60c is wound around a pulley E4 fixed to the crankshaft E3 of the engine E.
  • the crankshaft E3 is connected to the output shaft 20b via a pulley E4, a belt 60c, and a pulley 201b.
  • the mechanical energy output from the expander 20 assists the rotational output of the engine E.
  • the pump 40 is driven by the rotation of the motor 40a to pump the working fluid to the heat exchanger 50.
  • the control unit 75 has a range in which the difference between the high pressure side pressure and the low pressure side pressure does not exceed a preset control upper limit value. Then, the flow rate of the working fluid can be adjusted through the rotation speed control of the motor 40a so that the high-pressure side pressure is maintained at a constant value. As a result, the difference between the high pressure side pressure and the low pressure side pressure can be increased as much as possible within a range not exceeding the control upper limit value.
  • the control unit 75 controls the motor 40a so that the rotation speed of the motor 40a decreases. According to this, the flow rate of the working fluid pumped to the heat exchanger 50 by the pump 40 can be reduced, and as a result, the difference between the high pressure side pressure and the low pressure side pressure is set to a preset control upper limit value.
  • the high pressure side pressure can be lowered so as not to exceed. Therefore, it is possible to prevent the difference between the high pressure side pressure and the low pressure side pressure from becoming too large.
  • a power generator 20 a may be connected to the expander 20.
  • the control unit 75 causes the difference between the high pressure side pressure and the low pressure side pressure to exceed the preset control upper limit value.
  • the rotational speed of the generator 20a is controlled to keep the high-pressure side pressure at a constant value.
  • the difference between the high pressure side pressure and the low pressure side pressure can be increased as much as possible within a range not exceeding the control upper limit value.
  • the control unit 75 controls the generator 20a so that the rotational speed of the generator 20a increases.
  • bypass passage 71 may be connected to the second passage 22. Further, the other end of the bypass passage 71 may be connected to the fourth passage 24. The point is that a part of the working fluid flowing through the passage extending from the outlet of the pump 40 to the inlet of the expander 20 is transferred by the bypass passage 71 to the passage extending from the outlet of the expander 20 to the inlet of the pump 40. What is necessary is just to be able to bypass.
  • the first pressure sensor 72 may be provided in the third passage 23.
  • a temperature sensor for detecting the temperature of the working fluid condensed and liquefied in the condenser 30 (specifically, the temperature of the working fluid flowing from the outlet of the condenser 30 to the subcooler) may be provided. Then, the control unit 75 may calculate the pressure of the working fluid based on the temperature of the working fluid detected by the temperature sensor.
  • the temperature sensor and the control unit 75 constitute a pressure detection device that detects the low-pressure side pressure.
  • the fluid from the exhaust heat source for example, engine cooling water, supercharged air, EGR gas, or the like flowing through a cooling water circulation path connected to the engine E may be used.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Engine Equipment That Uses Special Cycles (AREA)

Abstract

A Rankine cycle device, provided with: a pump for pumping the working fluid; a heat exchanger for exchanging heat between the working fluid pumped by the pump and a fluid from the heat discharge source; an expander for causing the working fluid heat-exchanged by the heat exchanger to expand and outputting the mechanical energy; a condenser for causing the working fluid caused to expand in the expander to condense, the pump, the heat exchanger, the expander, and the condenser being connected in sequence so as to form a working fluid circuit in which the working fluid circulates; a pressure detection device for detecting the low-pressure-side pressure, which is the pressure of the working fluid flowing from the exit of the expander to the entrance of the pump; and a pressure control device for controlling the high-pressure-side pressure, which is the pressure of the working fluid flowing from the exit of the pump to the entrance of the expander. The pressure control device is constituted so as to control the high-pressure-side pressure so that the high-pressure-side pressure remains constant, even if the low-pressure-side pressure decreases, as long as the difference between the high-pressure-side pressure and the low-pressure-side pressure does not exceed a maximum control limit set in advance.

Description

ランキンサイクル装置Rankine cycle equipment
　本発明は、ランキンサイクル装置に関する。 The present invention relates to a Rankine cycle device.
　ランキンサイクル装置は、作動流体を圧送するポンプと、ポンプにより圧送された作動流体を排熱源からの流体と熱交換させる熱交換器と、熱交換器で熱交換された作動流体を膨張させて機械的エネルギーを出力する膨張機と、膨張機で膨張された作動流体を凝縮させる凝縮器と、を有している。そして、ポンプ、熱交換器、膨張機、及び凝縮器が順次接続されて作動流体が循環する作動流体回路が形成されている。 The Rankine cycle device includes a pump that pumps the working fluid, a heat exchanger that exchanges heat with the fluid from the exhaust heat source, and a working fluid that is heat-exchanged by the heat exchanger. And an expander that outputs dynamic energy and a condenser that condenses the working fluid expanded by the expander. A pump, a heat exchanger, an expander, and a condenser are sequentially connected to form a working fluid circuit in which the working fluid circulates.
　上記作動流体回路において、ポンプの出口から膨張機の入口までを流れる作動流体の圧力は「高圧側圧力（蒸発圧力）」であり、膨張機の出口からポンプの入口までを流れる作動流体の圧力は前記高圧側圧力よりも低い「低圧側圧力（凝縮圧力）」である。この高圧側圧力と低圧側圧力との差が小さければ小さいほど、膨張機は、作動流体の有する熱エネルギーを回転エネルギー等の機械的エネルギーに有効に変換することができず、その結果として、大きな機械的エネルギーを出力することができない。 In the above working fluid circuit, the pressure of the working fluid flowing from the outlet of the pump to the inlet of the expander is “high pressure side pressure (evaporation pressure)”, and the pressure of the working fluid flowing from the outlet of the expander to the inlet of the pump is The “low pressure side pressure (condensation pressure)” is lower than the high pressure side pressure. The smaller the difference between the high-pressure side pressure and the low-pressure side pressure is, the more the expander cannot effectively convert the thermal energy of the working fluid into mechanical energy such as rotational energy. The mechanical energy cannot be output.
　そこで、特許文献１には、作動流体回路を流れる作動流体の高圧側圧力と低圧側圧力との差を検出する圧力差検出装置と、圧力差検出装置によって検出された圧力差が予め定められた所定圧力差を下回った時に、所定圧力差となるように圧力差を増加させる圧力差増加装置とを備えたランキンサイクル装置が開示されている。また、特許文献２には、作動流体回路を流れる作動流体の高圧側圧力と低圧側圧力との差を一定に保つように制御することが開示されている。これらによれば、高圧側圧力と低圧側圧力との差が小さくなり過ぎてしまうことが防止され、膨張機は安定した機械的エネルギーを出力することが可能となる。 Therefore, in Patent Document 1, a pressure difference detection device that detects a difference between a high-pressure side pressure and a low-pressure side pressure of the working fluid flowing in the working fluid circuit, and a pressure difference detected by the pressure difference detection device are determined in advance. A Rankine cycle device is disclosed that includes a pressure difference increasing device that increases a pressure difference so as to be a predetermined pressure difference when the pressure difference falls below a predetermined pressure difference. Patent Document 2 discloses that control is performed such that the difference between the high-pressure side pressure and the low-pressure side pressure of the working fluid flowing in the working fluid circuit is kept constant. According to these, the difference between the high-pressure side pressure and the low-pressure side pressure is prevented from becoming too small, and the expander can output stable mechanical energy.
特開２００７－２５５３２７号公報JP 2007-255327 A 特開２００８－２９７９６１号公報JP 2008-297961 A
　しかし、例えば、膨張機で膨張された作動流体を凝縮器において外気で冷却して凝縮する場合、外気の温度が低ければ低いほど、作動流体が冷却され易くなって作動流体の凝縮圧力が低くなる。このような状況において、特許文献１の技術では、蒸発圧力と凝縮圧力との差が大きくなり過ぎて、膨張機やポンプの信頼性が低下してしまう虞がある。 However, for example, when the working fluid expanded by the expander is cooled by outside air in the condenser and condensed, the lower the temperature of the outside air, the easier the working fluid is cooled and the lower the condensation pressure of the working fluid. . Under such circumstances, in the technique of Patent Document 1, the difference between the evaporation pressure and the condensation pressure becomes too large, and the reliability of the expander and the pump may be reduced.
　一方、特許文献２の技術では、蒸発圧力と凝縮圧力との差が一定に保たれるように制御されている。このため、例えば、凝縮圧力が低くなると、圧力差が膨張機やポンプの信頼性が保たれる範囲にある場合であっても蒸発圧力が低くなってしまう。つまり、蒸発圧力と凝縮圧力との差を一定値よりも大きくすることができず、その結果、膨張機から出力される機械的エネルギーを極力大きくすることができない。 On the other hand, in the technique of Patent Document 2, the difference between the evaporation pressure and the condensation pressure is controlled to be kept constant. For this reason, for example, when the condensing pressure is lowered, the evaporation pressure is lowered even when the pressure difference is in a range where the reliability of the expander and the pump is maintained. That is, the difference between the evaporation pressure and the condensation pressure cannot be made larger than a certain value, and as a result, the mechanical energy output from the expander cannot be made as large as possible.
　本開示の目的は、膨張機やポンプの信頼性を確保することができるとともに、膨張機から出力される機械的エネルギーを極力大きくすることができるランキンサイクル装置を提供することにある。 An object of the present disclosure is to provide a Rankine cycle device that can ensure the reliability of the expander and the pump and can increase the mechanical energy output from the expander as much as possible.
　上記目的を達成するためのランキンサイクル装置は、作動流体を圧送するポンプと、前記ポンプにより圧送された作動流体を排熱源からの流体と熱交換させる熱交換器と、前記熱交換器で熱交換された作動流体を膨張させて機械的エネルギーを出力する膨張機と、前記膨張機で膨張された作動流体を凝縮させる凝縮器であって、前記ポンプ、前記熱交換器、前記膨張機、及び前記凝縮器は、作動流体が循環する作動流体回路を形成するように順次接続される、前記凝縮器と、前記膨張機の出口から前記ポンプの入口までを流れる作動流体の圧力である低圧側圧力を検出する圧力検出装置と、前記ポンプの出口から前記膨張機の入口までを流れる作動流体の圧力である高圧側圧力を制御する圧力制御装置と、を備える。前記圧力制御装置は、前記高圧側圧力と前記低圧側圧力との差が予め設定された制御上限値を越えない範囲では、前記低圧側圧力が低下しても前記高圧側圧力を一定に保つように制御するよう構成される。 The Rankine cycle device for achieving the above object includes a pump that pumps a working fluid, a heat exchanger that exchanges heat between the working fluid pumped by the pump and a fluid from an exhaust heat source, and heat exchange using the heat exchanger. An expander that expands the generated working fluid to output mechanical energy, and a condenser that condenses the working fluid expanded by the expander, the pump, the heat exchanger, the expander, and the The condenser is connected in series to form a working fluid circuit through which the working fluid circulates, and a low pressure side pressure that is a pressure of the working fluid flowing from the outlet of the expander to the inlet of the pump. And a pressure control device that controls a high-pressure side pressure that is a pressure of a working fluid that flows from the outlet of the pump to the inlet of the expander. The pressure control device keeps the high-pressure side pressure constant even when the low-pressure side pressure is reduced, as long as the difference between the high-pressure side pressure and the low-pressure side pressure does not exceed a preset control upper limit value. Configured to control.
実施形態におけるランキンサイクル装置を示す模式図。The schematic diagram which shows the Rankine cycle apparatus in embodiment. 高圧側圧力及び低圧側圧力の変化を示すグラフ。The graph which shows the change of a high pressure side pressure and a low pressure side pressure. 別の実施形態における高圧側圧力及び低圧側圧力の変化を示すグラフ。The graph which shows the change of the high voltage | pressure side pressure in another embodiment, and a low voltage | pressure side pressure. 別の実施形態におけるランキンサイクル装置を示す模式図。The schematic diagram which shows the Rankine-cycle apparatus in another embodiment. 別の実施形態におけるランキンサイクル装置を示す模式図。The schematic diagram which shows the Rankine-cycle apparatus in another embodiment.
　以下、一実施形態に係る車両に搭載されるランキンサイクル装置を図１及び図２にしたがって説明する。 Hereinafter, a Rankine cycle device mounted on a vehicle according to an embodiment will be described with reference to FIGS. 1 and 2.
　図１に示すように、ランキンサイクル装置１０は、作動流体が循環する作動流体回路１１を備える。作動流体回路１１は、順次接続された膨張機２０、凝縮器３０、ポンプ４０、熱交換器５０を含む。作動流体は、膨張機２０、凝縮器３０、ポンプ４０、熱交換器５０の並び順に沿って流れて作動流体回路１１を循環するようになっている。 As shown in FIG. 1, the Rankine cycle device 10 includes a working fluid circuit 11 through which a working fluid circulates. The working fluid circuit 11 includes an expander 20, a condenser 30, a pump 40, and a heat exchanger 50 that are sequentially connected. The working fluid flows along the arrangement order of the expander 20, the condenser 30, the pump 40, and the heat exchanger 50 and circulates in the working fluid circuit 11.
　熱交換器５０は、吸熱器５０ａと放熱器５０ｂとを有する。吸熱器５０ａは、ポンプ４０の出口と第１通路２１を介して接続されている。放熱器５０ｂは、排熱源としてのエンジンＥに接続された排気通路Ｅ１の周囲に設けられている。エンジンＥの排気は、放熱器５０ｂで放熱された後にマフラＥ２から排気される。 The heat exchanger 50 includes a heat absorber 50a and a heat radiator 50b. The heat absorber 50 a is connected to the outlet of the pump 40 through the first passage 21. The radiator 50b is provided around the exhaust passage E1 connected to the engine E as an exhaust heat source. The exhaust of the engine E is exhausted from the muffler E2 after being radiated by the radiator 50b.
　熱交換器５０の吸熱器５０ａと膨張機２０の入口とは第２通路２２を介して接続されている。膨張機２０の出口と凝縮器３０の入口とは第３通路２３を介して接続されている。凝縮器３０の出口とポンプ４０の入口とは第４通路２４を介して接続されている。熱交換器５０は、ポンプ４０により圧送された低温且つ高圧の液状態の作動流体を、エンジンＥの排気通路Ｅ１を流れる排気と熱交換させることで高温且つ高圧のガス状態の作動流体に変化させる。凝縮器３０は、膨張機２０で膨張し高温かつ低圧のガス状態となった作動流体を、外気と熱交換させることで低温かつ低圧の液状態の作動流体に変化させる。 The heat absorber 50 a of the heat exchanger 50 and the inlet of the expander 20 are connected via the second passage 22. The outlet of the expander 20 and the inlet of the condenser 30 are connected via a third passage 23. The outlet of the condenser 30 and the inlet of the pump 40 are connected via the fourth passage 24. The heat exchanger 50 changes the working fluid in a low-temperature and high-pressure liquid state pumped by the pump 40 into a high-temperature and high-pressure working fluid by exchanging heat with the exhaust flowing through the exhaust passage E1 of the engine E. . The condenser 30 changes the working fluid that has been expanded in the expander 20 and turned into a high-temperature and low-pressure gas state into a low-temperature and low-pressure liquid-state working fluid by exchanging heat with the outside air.
　ランキンサイクル装置１０は、ポンプ４０のポンプ軸及び膨張機２０の出力軸の両方として機能する駆動軸６０ａを含む。駆動軸６０ａの端部にはプーリ６０ｂが止着されている。プーリ６０ｂにはベルト６０ｃが巻き掛けられている。ベルト６０ｃは、エンジンＥの回転出力軸であるクランク軸Ｅ３に止着されたプーリＥ４に巻き掛けられている。クランク軸Ｅ３は、プーリＥ４、ベルト６０ｃ及びプーリ６０ｂを介して駆動軸６０ａと連結している。 Rankine cycle device 10 includes a drive shaft 60 a that functions as both a pump shaft of pump 40 and an output shaft of expander 20. A pulley 60b is fixed to the end of the drive shaft 60a. A belt 60c is wound around the pulley 60b. The belt 60c is wound around a pulley E4 fixed to a crankshaft E3 that is a rotation output shaft of the engine E. The crankshaft E3 is connected to the drive shaft 60a via a pulley E4, a belt 60c, and a pulley 60b.
　作動流体回路１１は、一端が第１通路２１（すなわち、ポンプ４０の出口と熱交換器５０との間を延びる通路）に接続されるとともに、他端が第３通路２３（すなわち、膨張機２０の出口と凝縮器３０の入口との間を延びる通路）に接続されるバイパス通路７１を含む。バイパス通路７１には、ポンプ４０からバイパス通路７１と熱交換器５０とへそれぞれ流れる作動流体の流量を変更する流量調整バルブ７１ａが設けられている。流量調整バルブ７１ａは制御部７５に接続されている。制御部７５は、流量調整バルブ７１ａの開度を調整すべく、流量調整バルブ７１ａに信号を伝送する。 The working fluid circuit 11 has one end connected to the first passage 21 (that is, a passage extending between the outlet of the pump 40 and the heat exchanger 50) and the other end connected to the third passage 23 (that is, the expander 20). A bypass passage 71 connected to an outlet of the condenser 30 and an inlet of the condenser 30. The bypass passage 71 is provided with a flow rate adjusting valve 71a that changes the flow rate of the working fluid flowing from the pump 40 to the bypass passage 71 and the heat exchanger 50, respectively. The flow rate adjustment valve 71 a is connected to the control unit 75. The control unit 75 transmits a signal to the flow rate adjusting valve 71a in order to adjust the opening degree of the flow rate adjusting valve 71a.
　第４通路２４（すなわち、凝縮器３０の出口とポンプ４０の入口との間の通路）には、凝縮器３０を通過した作動流体の圧力である低圧側圧力（凝縮圧力）を検出する圧力検出装置としての第１圧力センサ７２が設けられている。第１圧力センサ７２は制御部７５に信号伝送可能であるように制御部７５に接続されている。第１圧力センサ７２は、検出結果を示す信号を制御部７５に送る。 In the fourth passage 24 (that is, the passage between the outlet of the condenser 30 and the inlet of the pump 40), pressure detection for detecting a low-pressure side pressure (condensation pressure) that is the pressure of the working fluid that has passed through the condenser 30. A first pressure sensor 72 as a device is provided. The first pressure sensor 72 is connected to the control unit 75 so that a signal can be transmitted to the control unit 75. The first pressure sensor 72 sends a signal indicating the detection result to the control unit 75.
　第２通路２２（すなわち、熱交換器５０と膨張機２０の入口との間を延びる通路）には、熱交換器５０を通過した作動流体の圧力である高圧側圧力（蒸発圧力）を検出する第２圧力センサ７３が設けられている。第２圧力センサ７３は制御部７５に信号伝送可能であるように制御部７５に接続されている。第２圧力センサ７３は、検出結果を示す信号を制御部７５に送る。 In the second passage 22 (that is, a passage extending between the heat exchanger 50 and the inlet of the expander 20), a high-pressure side pressure (evaporation pressure) that is the pressure of the working fluid that has passed through the heat exchanger 50 is detected. A second pressure sensor 73 is provided. The second pressure sensor 73 is connected to the control unit 75 so that signals can be transmitted to the control unit 75. The second pressure sensor 73 sends a signal indicating the detection result to the control unit 75.
　次に、本実施形態の作用について説明する。 Next, the operation of this embodiment will be described.
　ポンプ４０が駆動されると、ポンプ４０により作動流体が圧送されて作動流体回路１１内を作動流体が循環する。ポンプ４０から第１通路２１を介して熱交換器５０に送られた作動流体は、熱交換器５０を通過する際に排気と熱交換されて高温且つ高圧のガス状態となる。熱交換器５０を通過して高温且つ高圧のガス状態となった作動流体は、第２通路２２を介して膨張機２０の入口から膨張機２０に吸入される。膨張機２０に吸入された作動流体は膨張機２０で膨張し、それに伴い、作動流体の持つ熱エネルギーの一部が膨張機２０を通じて機械的エネルギーとして取り出されて、エンジンＥの回転出力を補助するために利用される。膨張機２０において降温及び降圧した作動流体は、膨張機２０の出口から第３通路２３を介して凝縮器３０へ吸入される。凝縮器３０に吸入された作動流体は、凝縮器３０で凝縮されて液化し、第４通路２４を介してポンプ４０に還流される。 When the pump 40 is driven, the working fluid is pumped by the pump 40 and circulates in the working fluid circuit 11. When the working fluid sent from the pump 40 to the heat exchanger 50 through the first passage 21 passes through the heat exchanger 50, it is heat-exchanged with the exhaust gas and becomes a high-temperature and high-pressure gas state. The working fluid that has passed through the heat exchanger 50 and is in a high-temperature and high-pressure gas state is sucked into the expander 20 from the inlet of the expander 20 via the second passage 22. The working fluid sucked into the expander 20 is expanded by the expander 20, and part of the thermal energy of the working fluid is taken out as mechanical energy through the expander 20 to assist the rotational output of the engine E. Used for. The working fluid whose temperature has been lowered and reduced in pressure in the expander 20 is sucked into the condenser 30 from the outlet of the expander 20 via the third passage 23. The working fluid sucked into the condenser 30 is condensed and liquefied by the condenser 30, and is returned to the pump 40 through the fourth passage 24.
　ここで、第１圧力センサ７２により検出される圧力は、凝縮器３０において作動流体と熱交換される外気の温度に大きく影響を受ける。例えば、外気の温度が高ければ高いほど、作動流体は凝縮器３０において冷却（凝縮）され難く、作動流体の圧力は低くなり難い。また、例えば、外気の温度が低ければ低いほど、作動流体は凝縮器３０において冷却（凝縮）され易く、作動流体の圧力は低くなり易い。 Here, the pressure detected by the first pressure sensor 72 is greatly affected by the temperature of the outside air that exchanges heat with the working fluid in the condenser 30. For example, the higher the temperature of the outside air, the harder the working fluid is cooled (condensed) in the condenser 30 and the lower the pressure of the working fluid. Further, for example, the lower the temperature of the outside air, the easier the working fluid is cooled (condensed) in the condenser 30 and the pressure of the working fluid tends to be low.
　図２には、第１圧力センサ７２及び第２圧力センサ７３によりそれぞれ検出される圧力の変化（低圧側圧力及び高圧側圧力の変化）を表している。時間Ｔ１から時間Ｔ２までの間では、第１圧力センサ７２により検出された圧力Ｐ１１と、第２圧力センサ７３により検出された圧力Ｐ２１との圧力差Ｚ１は一定であるとともに、予め設定された制御上限値よりも小さくなっている。ここで、「制御上限値Ｚ」とは、膨張機２０やポンプ４０が、高圧側圧力と低圧側圧力との差によって受ける荷重により機器の信頼性を損なわない高圧側圧力と低圧側圧力との差の上限値のことを言う。 FIG. 2 shows changes in pressure (changes in low-pressure side pressure and high-pressure side pressure) detected by the first pressure sensor 72 and the second pressure sensor 73, respectively. Between time T1 and time T2, the pressure difference Z1 between the pressure P11 detected by the first pressure sensor 72 and the pressure P21 detected by the second pressure sensor 73 is constant, and a preset control is performed. It is smaller than the upper limit. Here, the “control upper limit value Z” is the high pressure side pressure and the low pressure side pressure at which the expander 20 and the pump 40 do not impair the reliability of the equipment due to the load received by the difference between the high pressure side pressure and the low pressure side pressure. This is the upper limit of the difference.
　時間Ｔ２から時間Ｔ３の間に、外気の温度が時間Ｔ１から時間Ｔ２のときよりも徐々に低下していったとする。すると、作動流体は、時間Ｔ２から時間Ｔ３の間に、凝縮器３０において時間Ｔ１から時間Ｔ２のときの温度よりも低い温度に冷却されていき、作動流体の圧力は徐々に低くなっていく。そして、時間Ｔ３のときに第１圧力センサ７２により検出された圧力Ｐ１２は、時間Ｔ２のときに第１圧力センサ７２により検出された圧力Ｐ１１よりも低くなっている。 Suppose that the temperature of the outside air gradually decreases from time T1 to time T2 from time T2 to time T3. Then, the working fluid is cooled to a temperature lower than the temperature at the time T1 to the time T2 in the condenser 30 from the time T2 to the time T3, and the pressure of the working fluid gradually decreases. The pressure P12 detected by the first pressure sensor 72 at time T3 is lower than the pressure P11 detected by the first pressure sensor 72 at time T2.
　ここで、第１圧力センサ７２により検出された圧力Ｐ１２と、第２圧力センサ７３により検出された圧力Ｐ２１との圧力差Ｚ２が、予め設定された制御上限値に達したとする。このとき、制御部７５は、高圧側圧力と低圧側圧力との差が制御上限値を越えない範囲では、第１通路２１からバイパス通路７１を通って第３通路２３に流れる作動流体の流量が減少するように、流量調整バルブ７１ａの開度を制御している。その結果、高圧側圧力が低圧側圧力に追従して徐々に低くなることなく一定値に保たれ、高圧側圧力と低圧側圧力との差が、制御上限値を越えない範囲内で極力大きくなっている。よって、本実施形態では、制御部７５は、高圧側圧力を制御する圧力制御装置として機能している。 Here, it is assumed that the pressure difference Z2 between the pressure P12 detected by the first pressure sensor 72 and the pressure P21 detected by the second pressure sensor 73 has reached a preset control upper limit value. At this time, the control unit 75 determines that the flow rate of the working fluid flowing from the first passage 21 through the bypass passage 71 to the third passage 23 is within a range where the difference between the high pressure side pressure and the low pressure side pressure does not exceed the control upper limit value. The opening degree of the flow rate adjustment valve 71a is controlled so as to decrease. As a result, the high-pressure side pressure is maintained at a constant value without gradually decreasing following the low-pressure side pressure, and the difference between the high-pressure side pressure and the low-pressure side pressure becomes as large as possible within the range not exceeding the control upper limit value. ing. Therefore, in the present embodiment, the control unit 75 functions as a pressure control device that controls the high-pressure side pressure.
　時間Ｔ３から時間Ｔ４までの間では、第１圧力センサ７２により検出された圧力Ｐ１２と、第２圧力センサ７３により検出された圧力Ｐ２１との圧力差Ｚ２は一定である。時間Ｔ４から時間Ｔ５までの間に、外気の温度が時間Ｔ３から時間Ｔ４の間の温度よりもさらに徐々に低下していったとする。すると、作動流体は、時間Ｔ４から時間Ｔ５までの間に、凝縮器３０において時間Ｔ３から時間Ｔ４の間の温度よりもさらに低い温度に冷却されていき、作動流体の圧力は徐々に低くなっていく。そして、時間Ｔ５のときに第１圧力センサ７２により検出された圧力Ｐ１３は、時間Ｔ４のときに第１圧力センサ７２により検出された圧力Ｐ１２よりも低くなっている。 Between time T3 and time T4, the pressure difference Z2 between the pressure P12 detected by the first pressure sensor 72 and the pressure P21 detected by the second pressure sensor 73 is constant. It is assumed that the temperature of the outside air further gradually decreases from the time T3 to the time T4 between the time T4 and the time T5. Then, the working fluid is cooled to a temperature further lower than the temperature between time T3 and time T4 in the condenser 30 between time T4 and time T5, and the pressure of the working fluid gradually decreases. Go. The pressure P13 detected by the first pressure sensor 72 at time T5 is lower than the pressure P12 detected by the first pressure sensor 72 at time T4.
　このとき、制御部７５は、第１通路２１からバイパス通路７１を通って第３通路２３へ流れる作動流体の流量が増大するように、流量調整バルブ７１ａの開度を制御する。これにより、ポンプ４０の出口から膨張機２０の入口までを流れる作動流体の流量が少なくなり、時間Ｔ５のときに第２圧力センサ７３により検出された圧力Ｐ２２が、時間Ｔ４のときに第２圧力センサ７３により検出された圧力Ｐ２１よりも低くなる。 At this time, the controller 75 controls the opening degree of the flow rate adjusting valve 71a so that the flow rate of the working fluid flowing from the first passage 21 through the bypass passage 71 to the third passage 23 increases. As a result, the flow rate of the working fluid flowing from the outlet of the pump 40 to the inlet of the expander 20 decreases, and the pressure P22 detected by the second pressure sensor 73 at time T5 is the second pressure at time T4. It becomes lower than the pressure P21 detected by the sensor 73.
　ここで、第１圧力センサ７２により検出された圧力Ｐ１３と、第２圧力センサ７３により検出された圧力Ｐ２２との圧力差Ｚ３は、予め設定された制御上限値になっている。すなわち、第１通路２１からバイパス通路７１を介して第３通路２３へ流れる作動流体の流量を変化させることで、圧力Ｐ１３と圧力Ｐ２２との圧力差Ｚ３が制御上限値になるように、流量調整バルブ７１ａの開度が制御部７５によって調整されている。その結果、高圧側圧力と低圧側圧力との差が制御上限値を越えないように、時間Ｔ４から時間Ｔ５までの間で高圧側圧力が低下するため、高圧側圧力と低圧側圧力との差が大きくなり過ぎてしまうことが防止されている。 Here, the pressure difference Z3 between the pressure P13 detected by the first pressure sensor 72 and the pressure P22 detected by the second pressure sensor 73 is a preset control upper limit value. That is, the flow rate adjustment is performed so that the pressure difference Z3 between the pressure P13 and the pressure P22 becomes the control upper limit value by changing the flow rate of the working fluid flowing from the first passage 21 to the third passage 23 via the bypass passage 71. The opening degree of the valve 71 a is adjusted by the control unit 75. As a result, the high pressure side pressure decreases from time T4 to time T5 so that the difference between the high pressure side pressure and the low pressure side pressure does not exceed the control upper limit value, so the difference between the high pressure side pressure and the low pressure side pressure. Is prevented from becoming too large.
　上記実施形態では以下の効果を得ることができる。 In the above embodiment, the following effects can be obtained.
　（１）ランキンサイクル装置１０は、膨張機２０の出口からポンプ４０の入口までを流れる作動流体の圧力である低圧側圧力を検出する第１圧力センサ７２を備える。また、作動流体回路１１において、一端が第１通路２１に接続されるとともに、他端が第３通路２３に接続されるバイパス通路７１を配設し、バイパス通路７１に、バイパス通路７１を流れる作動流体の流量と、熱交換器５０を流れる作動流体の流量とを変更する流量調整バルブ７１ａを設けた。そして、制御部７５は、第１通路２１からバイパス通路７１を通って第３通路２３へ流れる作動流体の流量を変化させることによって、ポンプ４０の出口から膨張機２０の入口までを流れる作動流体の圧力である高圧側圧力を制御する。 (1) The Rankine cycle apparatus 10 includes a first pressure sensor 72 that detects a low-pressure side pressure that is a pressure of a working fluid that flows from the outlet of the expander 20 to the inlet of the pump 40. In the working fluid circuit 11, the bypass passage 71 having one end connected to the first passage 21 and the other end connected to the third passage 23 is disposed, and the operation flows through the bypass passage 71 through the bypass passage 71. A flow rate adjusting valve 71a for changing the flow rate of the fluid and the flow rate of the working fluid flowing through the heat exchanger 50 is provided. And the control part 75 changes the flow volume of the working fluid which flows into the 3rd channel | path 23 from the 1st channel | path 21 through the bypass channel | path 71, and thereby the working fluid which flows from the outlet of the pump 40 to the inlet of the expander 20 is changed. The high-pressure side pressure that is the pressure is controlled.
　制御部７５は、例えば、第１圧力センサ７２により検出される低圧側圧力が徐々に低くなっていったとしても、高圧側圧力と低圧側圧力との差が予め設定された制御上限値を越えない範囲では、第１通路２１からバイパス通路７１を通って第３通路２３へ流れる作動流体の流量を減少させる。よって、高圧側圧力が低圧側圧力に追従して徐々に低くなることなく一定値に保たれるように高圧側圧力を制御することができる。その結果、高圧側圧力と低圧側圧力との差を、制御上限値を越えない範囲内で極力大きくすることができる。また、例えば、第１圧力センサ７２により検出される低圧側圧力が過度に低くなった場合に、第１通路２１からバイパス通路７１を通って第３通路２３へ流れる作動流体の量を増大させることで、ポンプ４０の出口から膨張機２０の入口までを流れる作動流体の流量を少なくすることができる。その結果として、高圧側圧力と低圧側圧力との差が制御上限値を越えないように高圧側圧力を低くすることができるため、高圧側圧力と低圧側圧力との差が大きくなり過ぎてしまうことを防止することができる。その結果、膨張機２０やポンプ４０の信頼性を確保することができるとともに、膨張機２０から出力される機械的エネルギーを極力大きくすることができる。 For example, even if the low-pressure side pressure detected by the first pressure sensor 72 gradually decreases, the control unit 75 causes the difference between the high-pressure side pressure and the low-pressure side pressure to exceed a preset control upper limit value. In the absence range, the flow rate of the working fluid flowing from the first passage 21 through the bypass passage 71 to the third passage 23 is decreased. Therefore, the high-pressure side pressure can be controlled so that the high-pressure side pressure is maintained at a constant value without gradually decreasing following the low-pressure side pressure. As a result, the difference between the high pressure side pressure and the low pressure side pressure can be increased as much as possible within a range not exceeding the control upper limit value. Further, for example, when the low-pressure side pressure detected by the first pressure sensor 72 is excessively low, the amount of working fluid flowing from the first passage 21 to the third passage 23 through the bypass passage 71 is increased. Thus, the flow rate of the working fluid flowing from the outlet of the pump 40 to the inlet of the expander 20 can be reduced. As a result, the high pressure side pressure can be lowered so that the difference between the high pressure side pressure and the low pressure side pressure does not exceed the control upper limit value, so the difference between the high pressure side pressure and the low pressure side pressure becomes too large. This can be prevented. As a result, the reliability of the expander 20 and the pump 40 can be ensured, and the mechanical energy output from the expander 20 can be maximized.
　（２）本実施形態では、第１通路２１からバイパス通路７１を通って第３通路２３へ流れる作動流体の流量を変化させることで高圧側圧力を制御するようにした。よって、例えば、高圧側圧力を制御するために、ポンプ４０を駆動させるモータの回転数を制御したり、膨張機２０の回転数を制御したりするという必要が無く、単一の駆動軸６０ａがポンプ４０のポンプ軸及び膨張機２０の両方として機能することが可能となり、ランキンサイクル装置１０の構成を簡素化することが可能となる。 (2) In the present embodiment, the high pressure side pressure is controlled by changing the flow rate of the working fluid flowing from the first passage 21 to the third passage 23 through the bypass passage 71. Therefore, for example, in order to control the high-pressure side pressure, there is no need to control the rotation speed of the motor that drives the pump 40 or the rotation speed of the expander 20, and the single drive shaft 60a can be controlled. It becomes possible to function as both the pump shaft of the pump 40 and the expander 20, and the configuration of the Rankine cycle apparatus 10 can be simplified.
　なお、上記実施形態は以下のように変更してもよい。 Note that the above embodiment may be modified as follows.
　実施形態において、高圧側圧力の上限値を予め設定してもよい。例えば、図３に示すように、時間Ｔ６から時間Ｔ７までの間では、第１圧力センサ７２により検出された圧力Ｐ１４と、第２圧力センサ７３により検出された圧力Ｐ２３との圧力差Ｚ４は一定である。このとき、第２圧力センサ７３により検出された圧力Ｐ２３は、既に高圧側圧力の上限値に達しているとする。そして、時間Ｔ７から時間Ｔ８までの間に、外気の温度が時間Ｔ６から時間Ｔ７のときよりも徐々に上昇していったとする。すると、作動流体は、時間Ｔ７から時間Ｔ８までの間に、凝縮器３０において時間Ｔ６から時間Ｔ７のときよりも高い温度に凝縮されていき、作動流体の圧力は徐々に高くなっていく。そして、時間Ｔ８のときに第１圧力センサ７２により検出された圧力Ｐ１５は、時間Ｔ７のときに第１圧力センサ７２により検出された圧力Ｐ１４よりも高くなっており、高圧側圧力と低圧側圧力との差が小さくなる。ここで、制御部７５は、高圧側圧力が上限値を越えないように高圧側圧力を制御する。具体的には、制御部７５がポンプ４０を駆動させるモータの回転数を制御することで、ポンプ４０から熱交換器５０に圧送される作動流体の流量を変化させ、高圧側圧力が上限値を越えないようにする。これによれば、高圧側圧力と低圧側圧力との差を、制御上限値を越えない範囲内で極力大きくしようとしたことに起因して、高圧側圧力が過度に高くなってしまう、といった事態を防止することができる。その結果、膨張機２０やポンプ４０の信頼性をさらに確保することができる。 In the embodiment, an upper limit value of the high pressure side pressure may be set in advance. For example, as shown in FIG. 3, the pressure difference Z4 between the pressure P14 detected by the first pressure sensor 72 and the pressure P23 detected by the second pressure sensor 73 is constant between time T6 and time T7. It is. At this time, it is assumed that the pressure P23 detected by the second pressure sensor 73 has already reached the upper limit value of the high-pressure side pressure. Then, it is assumed that the temperature of the outside air gradually rises from time T6 to time T7 from time T7 to time T8. Then, the working fluid is condensed to a temperature higher than that at the time T6 to the time T7 in the condenser 30 from the time T7 to the time T8, and the pressure of the working fluid is gradually increased. The pressure P15 detected by the first pressure sensor 72 at time T8 is higher than the pressure P14 detected by the first pressure sensor 72 at time T7, and the high pressure side pressure and the low pressure side pressure are detected. The difference with is small. Here, the control unit 75 controls the high pressure side pressure so that the high pressure side pressure does not exceed the upper limit value. Specifically, the control unit 75 controls the rotational speed of the motor that drives the pump 40, thereby changing the flow rate of the working fluid pumped from the pump 40 to the heat exchanger 50, and the high-pressure side pressure reaches the upper limit value. Do not exceed. According to this, a situation in which the high pressure side pressure becomes excessively high due to an attempt to increase the difference between the high pressure side pressure and the low pressure side pressure as much as possible within a range not exceeding the control upper limit value. Can be prevented. As a result, the reliability of the expander 20 and the pump 40 can be further ensured.
　駆動軸６０ａが、ポンプ４０のポンプ軸及び膨張機２０の出力軸の両方として機能していなくてもよい。そして、例えば、図４に示すように、ランキンサイクル装置１０は、ポンプ４０を駆動させるモータ４０ａを備えていてもよい。また、膨張機２０の出力軸２０ｂにはプーリ２０１ｂが止着されている。プーリ２０１ｂにはベルト６０ｃが巻き掛けられている。ベルト６０ｃは、エンジンＥのクランク軸Ｅ３に止着されたプーリＥ４に巻き掛けられている。クランク軸Ｅ３は、プーリＥ４、ベルト６０ｃ及びプーリ２０１ｂを介して出力軸２０ｂと連結している。膨張機２０から出力された機械的エネルギーはエンジンＥの回転出力を補助する。 The drive shaft 60a may not function as both the pump shaft of the pump 40 and the output shaft of the expander 20. For example, as shown in FIG. 4, the Rankine cycle apparatus 10 may include a motor 40 a that drives the pump 40. A pulley 201b is fixed to the output shaft 20b of the expander 20. A belt 60c is wound around the pulley 201b. The belt 60c is wound around a pulley E4 fixed to the crankshaft E3 of the engine E. The crankshaft E3 is connected to the output shaft 20b via a pulley E4, a belt 60c, and a pulley 201b. The mechanical energy output from the expander 20 assists the rotational output of the engine E.
　ポンプ４０はモータ４０ａの回転によって駆動して、作動流体を熱交換器５０に圧送するようになっている。制御部７５は、例えば、第１圧力センサ７２により検出される圧力が徐々に低くなっていったとしても、高圧側圧力と低圧側圧力との差が予め設定された制御上限値を越えない範囲では、高圧側圧力が一定値に保たれるように、作動流体の流量をモータ４０ａの回転数制御を通じて調整することができる。その結果、高圧側圧力と低圧側圧力との差を、制御上限値を越えない範囲内で極力大きくすることができる。また、例えば、第１圧力センサ７２により検出される圧力が過度に低くなった場合に、制御部７５がモータ４０ａの回転数が減少するようにモータ４０ａを制御する。これによれば、ポンプ４０により熱交換器５０へ圧送される作動流体の流量を少なくすることができ、その結果として、高圧側圧力と低圧側圧力との差が予め設定された制御上限値を越えないように高圧側圧力を低くすることができる。よって、高圧側圧力と低圧側圧力との差が大きくなり過ぎてしまうことを防止することができる。 The pump 40 is driven by the rotation of the motor 40a to pump the working fluid to the heat exchanger 50. For example, even if the pressure detected by the first pressure sensor 72 gradually decreases, the control unit 75 has a range in which the difference between the high pressure side pressure and the low pressure side pressure does not exceed a preset control upper limit value. Then, the flow rate of the working fluid can be adjusted through the rotation speed control of the motor 40a so that the high-pressure side pressure is maintained at a constant value. As a result, the difference between the high pressure side pressure and the low pressure side pressure can be increased as much as possible within a range not exceeding the control upper limit value. For example, when the pressure detected by the first pressure sensor 72 is excessively low, the control unit 75 controls the motor 40a so that the rotation speed of the motor 40a decreases. According to this, the flow rate of the working fluid pumped to the heat exchanger 50 by the pump 40 can be reduced, and as a result, the difference between the high pressure side pressure and the low pressure side pressure is set to a preset control upper limit value. The high pressure side pressure can be lowered so as not to exceed. Therefore, it is possible to prevent the difference between the high pressure side pressure and the low pressure side pressure from becoming too large.
　また、図５に示すように、膨張機２０には発電機２０ａが接続されていてもよい。そして、制御部７５は、例えば、第１圧力センサ７２により検出される圧力が徐々に低くなっていったとしても、高圧側圧力と低圧側圧力との差が予め設定された制御上限値を越えない範囲では、発電機２０ａの回転数を制御し、高圧側圧力を一定値に保つ。これにより、高圧側圧力と低圧側圧力との差を、制御上限値を越えない範囲内で極力大きくすることができる。また、例えば、第１圧力センサ７２により検出される圧力が過度に低くなった場合に、制御部７５が発電機２０ａの回転数が上昇するように発電機２０ａを制御する。これによれば、発電機２０ａと共に駆動する膨張機２０の回転数が上昇するように制御され、高圧側圧力を低くすることができる。その結果として、高圧側圧力と低圧側圧力との差が予め設定された制御上限値を越えないようにすることができ、高圧側圧力と低圧側圧力との差が大きくなり過ぎてしまうことを防止することができる。 Further, as shown in FIG. 5, a power generator 20 a may be connected to the expander 20. For example, even if the pressure detected by the first pressure sensor 72 gradually decreases, the control unit 75 causes the difference between the high pressure side pressure and the low pressure side pressure to exceed the preset control upper limit value. In the absence range, the rotational speed of the generator 20a is controlled to keep the high-pressure side pressure at a constant value. Thereby, the difference between the high pressure side pressure and the low pressure side pressure can be increased as much as possible within a range not exceeding the control upper limit value. For example, when the pressure detected by the first pressure sensor 72 is excessively low, the control unit 75 controls the generator 20a so that the rotational speed of the generator 20a increases. According to this, it controls so that the rotation speed of the expander 20 driven with the generator 20a rises, and it can make a high voltage | pressure side pressure low. As a result, it is possible to prevent the difference between the high-pressure side pressure and the low-pressure side pressure from exceeding a preset control upper limit value, and the difference between the high-pressure side pressure and the low-pressure side pressure becomes too large. Can be prevented.
　バイパス通路７１の一端は第２通路２２に接続されていてもよい。また、バイパス通路７１の他端は第４通路２４に接続されていてもよい。要は、バイパス通路７１によって、ポンプ４０の出口から膨張機２０の入口までの間を延びる通路を流れる作動流体の一部が、膨張機２０の出口からポンプ４０の入口までの間を延びる通路へバイパス可能であればよい。 One end of the bypass passage 71 may be connected to the second passage 22. Further, the other end of the bypass passage 71 may be connected to the fourth passage 24. The point is that a part of the working fluid flowing through the passage extending from the outlet of the pump 40 to the inlet of the expander 20 is transferred by the bypass passage 71 to the passage extending from the outlet of the expander 20 to the inlet of the pump 40. What is necessary is just to be able to bypass.
　第１圧力センサ７２が第３通路２３に設けられていてもよい。 The first pressure sensor 72 may be provided in the third passage 23.
　凝縮器３０において凝縮されて液化した作動流体の温度（詳細には、凝縮器３０の出口から過冷却器までの間を流れる作動流体の温度）を検出する温度センサを設けてもよい。そして、制御部７５は、温度センサにより検出された作動流体の温度に基づいて作動流体の圧力を算出するようにしてもよい。この場合、温度センサ及び制御部７５により、低圧側圧力を検出する圧力検出装置が構成されている。 A temperature sensor for detecting the temperature of the working fluid condensed and liquefied in the condenser 30 (specifically, the temperature of the working fluid flowing from the outlet of the condenser 30 to the subcooler) may be provided. Then, the control unit 75 may calculate the pressure of the working fluid based on the temperature of the working fluid detected by the temperature sensor. In this case, the temperature sensor and the control unit 75 constitute a pressure detection device that detects the low-pressure side pressure.
　排熱源からの流体としては、例えば、エンジンＥに接続された冷却水循環経路を流れるエンジン冷却水や過給空気、ＥＧＲガス等を利用してもよい。 As the fluid from the exhaust heat source, for example, engine cooling water, supercharged air, EGR gas, or the like flowing through a cooling water circulation path connected to the engine E may be used.

Claims (5)

  1. 　作動流体を圧送するポンプと、
    　前記ポンプにより圧送された作動流体を排熱源からの流体と熱交換させる熱交換器と、
    　前記熱交換器で熱交換された作動流体を膨張させて機械的エネルギーを出力する膨張機と、
    　前記膨張機で膨張された作動流体を凝縮させる凝縮器であって、前記ポンプ、前記熱交換器、前記膨張機、及び前記凝縮器は、作動流体が循環する作動流体回路を形成するように順次接続される、前記凝縮器と、
    　前記膨張機の出口から前記ポンプの入口までを流れる作動流体の圧力である低圧側圧力を検出する圧力検出装置と、
    　前記ポンプの出口から前記膨張機の入口までを流れる作動流体の圧力である高圧側圧力を制御する圧力制御装置と、を備え、
    　前記圧力制御装置は、前記高圧側圧力と前記低圧側圧力との差が予め設定された制御上限値を越えない範囲では、前記低圧側圧力が低下しても前記高圧側圧力を一定に保つように制御するよう構成されるランキンサイクル装置。     A pump for pumping the working fluid;
    A heat exchanger that exchanges heat between the working fluid pumped by the pump and the fluid from the exhaust heat source;
    An expander that expands the working fluid heat-exchanged by the heat exchanger and outputs mechanical energy;
    A condenser that condenses the working fluid expanded by the expander, wherein the pump, the heat exchanger, the expander, and the condenser sequentially form a working fluid circuit through which the working fluid circulates. Connected to the condenser;
    A pressure detection device that detects a low-pressure side pressure that is a pressure of a working fluid flowing from an outlet of the expander to an inlet of the pump;
    A pressure control device that controls a high-pressure side pressure that is a pressure of a working fluid that flows from an outlet of the pump to an inlet of the expander,
    The pressure control device keeps the high-pressure side pressure constant even when the low-pressure side pressure is reduced, as long as the difference between the high-pressure side pressure and the low-pressure side pressure does not exceed a preset control upper limit value. A Rankine cycle device configured to be controlled.
  2. 　前記圧力制御装置は、前記高圧側圧力が予め設定された上限値を越えないように高圧側圧力を制御するよう構成される請求項１に記載のランキンサイクル装置。 The Rankine cycle device according to claim 1, wherein the pressure control device is configured to control the high-pressure side pressure so that the high-pressure side pressure does not exceed a preset upper limit value.
  3. 　前記作動流体回路は、前記ポンプの出口から前記膨張機の入口までの間の部分を、前記膨張機の出口から前記ポンプの入口までの間の部分に接続するバイパス通路を含み、
    　前記圧力制御装置は、前記バイパス通路を流れる作動流体の流量を変化させることで前記高圧側圧力を制御するよう構成される請求項１又は請求項２に記載のランキンサイクル装置。     The working fluid circuit includes a bypass passage connecting a portion between the outlet of the pump and the inlet of the expander to a portion between the outlet of the expander and the inlet of the pump;
    The Rankine cycle device according to claim 1 or 2, wherein the pressure control device is configured to control the high-pressure side pressure by changing a flow rate of the working fluid flowing through the bypass passage.
  4. 　前記圧力制御装置は、前記ポンプを駆動するモータの回転数を制御することで、前記高圧側圧力を制御するよう構成される請求項１又は請求項２に記載のランキンサイクル装置。 The Rankine cycle device according to claim 1 or 2, wherein the pressure control device is configured to control the high-pressure side pressure by controlling a rotation speed of a motor that drives the pump.
  5. 　前記圧力制御装置は、前記膨張機の回転数を制御することで、前記高圧側圧力を制御するよう構成される請求項１又は請求項２に記載のランキンサイクル装置。 The Rankine cycle device according to claim 1 or 2, wherein the pressure control device is configured to control the high-pressure side pressure by controlling a rotation speed of the expander.
PCT/JP2013/068105 2012-07-10 2013-07-02 Rankine cycle device WO2014010465A1 (en)

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JP2012067683A (en) * 2010-09-24 2012-04-05 Toyota Industries Corp Rankine cycle device

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