JP2013217222A - Rankine-cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To be able to cool EGR gas before sucked into an engine, while heating operating fluid before sucked into an expander.SOLUTION: A first EGR gas heat exchanger 51, a low-temperature heat source heat exchanger 53, and a second EGR gas heat exchanger 52 are connected in series between an outlet of a pump 40 and an inlet of an expander 20 in a coolant circulation circuit 11. In addition, the first EGR gas heat exchanger 51 is disposed at an upstream end in a flow direction of coolant from the outlet of the pump 40 toward the inlet of the expander 20, and the second EGR gas heat exchanger 52 is disposed at a downstream end in the flow direction of the coolant from the outlet of the pump 40 toward the inlet of the expander 20.

Description

  The present invention relates to a Rankine cycle apparatus.

  An example of this type of Rankine cycle apparatus is that of Patent Document 1. The Rankine cycle device of Patent Document 1 heats the working fluid flowing through the steam generator using EGR gas, which is part of combustion gas (exhaust gas) exhausted from the engine, as a heat source. Then, the working fluid heated by the steam generator is sucked into the expander, and the working fluid is decompressed and expanded substantially isentropically by the expander, thereby converting the thermal energy of the working fluid into mechanical energy such as rotational energy. Convert.

JP 2005-42618 A

  By the way, when high-temperature EGR gas is mixed with intake air and sucked into the engine again, the combustion temperature in the engine rises and nitrogen oxides (NOx) contained in the exhaust gas exhausted from the engine are generated. It becomes easy to do. Therefore, it is desirable that the EGR gas be sufficiently cooled by exchanging heat with the working fluid in the steam generator. Further, when a low-temperature working fluid is sucked into the expander, there is a possibility that mechanical energy cannot be sufficiently taken out by the expander. Therefore, it is desirable that the working fluid is sufficiently heated by heat exchange with the EGR gas in the steam generator.

  Therefore, in the Rankine cycle device, for example, a heat exchanger for a low-temperature heat source that exchanges the working fluid with a heat source having a temperature lower than that of EGR gas such as engine cooling water or intake air whose temperature has been increased by supercharging of the supercharger. Is disposed upstream of the steam generator in the flow direction of the working fluid. Then, when the working fluid passes through the heat exchanger for the low-temperature heat source, it is heated by heat exchange with a heat source having a temperature lower than that of the EGR gas, and when the working fluid passes through the steam generator, the working fluid exchanges heat with the EGR gas. And further heated, the working fluid can be sufficiently heated. However, since the working fluid is heat-exchanged with a heat source having a temperature lower than that of the EGR gas in the heat exchanger for the low-temperature heat source and the temperature rises, the EGR gas may not be sufficiently cooled in the steam generator. is there.

  Therefore, for example, the heat exchanger for a low-temperature heat source is arranged downstream of the steam generator in the flow direction of the working fluid. Then, since the EGR gas is heat-exchanged with the working fluid before heat exchange with the heat source having a lower temperature than the EGR gas in the heat exchanger for the low-temperature heat source in the steam generator, the EGR gas is sufficiently cooled. Can do. However, the working fluid may be heated to a temperature higher than the temperature of the heat source, which is lower than the EGR gas, by heat exchange with the EGR gas in the steam generator. In the heat exchanger for a low-temperature heat source, when the working fluid whose temperature has been raised by the steam generator and the heat source having a temperature lower than that of the EGR gas are heat-exchanged, the temperature of the working fluid decreases, There is a risk that heating will be insufficient.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to cool the EGR gas before being sucked into the engine and to supply the working fluid before being sucked into the expander. It is providing the Rankine-cycle apparatus which can be heated.

  In order to achieve the above object, the invention according to claim 1 is a pump that pumps a working fluid, and a plurality of EGR gases that exchange heat with the EGR gas exhausted from the engine. Heat exchanger, at least one heat exchanger for low-temperature heat source that exchanges heat between the working fluid and a heat source that is lower in temperature than the EGR gas, the plurality of EGR gas heat exchangers, and the low-temperature heat source A working fluid circuit is formed by an expander that outputs mechanical energy by expanding the working fluid heat-exchanged by the heat exchanger for heat and a condenser that condenses the working fluid expanded by the expander. Each EGR gas heat exchanger and low-temperature heat source heat exchanger are connected in series from the outlet of the pump to the inlet of the expander, and from the outlet of the pump to the inlet of the expander. The most upstream EGR gas heat exchanger, which is one of the plurality of EGR gas heat exchangers, is disposed on the most upstream side in the flow direction of the working fluid, and the expansion from the outlet of the pump A most downstream EGR gas heat exchanger, which is one of the plurality of EGR gas heat exchangers, is arranged at the most downstream in the flow direction of the working fluid to the inlet of the machine, and the most downstream The most upstream EGR gas in the flow direction of the EGR gas flows into the heat exchanger for EGR gas, and the most downstream EGR gas in the flow direction of the EGR gas flows into the heat exchanger for the uppermost flow EGR gas. The gist is to flow in.

  According to the present invention, the EGR gas passing through the heat exchanger for the most downstream EGR gas is heat-exchanged with the working fluid whose temperature has been increased by heat exchange in the heat exchanger for the low-temperature heat source. In the gas heat exchanger, heat is exchanged with the low-temperature working fluid immediately after being pumped from the pump, so that the EGR gas can be sufficiently cooled before being sucked into the engine. In addition, the working fluid that passes through the heat exchanger for the most upstream EGR gas is heated by heat exchange with the EGR gas, and then the temperature may decrease due to heat exchange in the heat exchanger for the low-temperature heat source. However, since the heat exchange with the EGR gas is performed in the heat exchanger for the most downstream EGR gas, the working fluid can be sufficiently heated before being sucked into the expander.

  According to a second aspect of the present invention, in the first aspect of the present invention, the working fluid circuit includes a working fluid bypass passage that bypasses the heat exchanger for the most upstream EGR gas, the working fluid bypass passage, and the outermost fluid passage. The gist of the invention is to provide a flow rate changing means for changing the flow rate of the working fluid flowing to the upstream EGR gas heat exchanger.

  For example, the flow rate changing means reduces the flow rate of the working fluid flowing to the most upstream EGR gas heat exchanger from the flow rate of the working fluid flowing to the working fluid bypass passage. As a result, the amount of heat that the EGR gas is taken away by the working fluid in the heat exchanger for the most upstream EGR gas is reduced, and it is possible to prevent the EGR gas from being overcooled. As a result, the temperature of the EGR gas becomes too low, and the water contained in the EGR gas is condensed and reacts with the sulfur oxide (SOx) to generate sulfuric acid. This sulfuric acid causes the EGR passage through which the EGR gas flows. It is possible to prevent the component parts from deteriorating.

  According to a third aspect of the present invention, in the first aspect of the present invention, in the working fluid circuit, the working fluid flows into the heat exchanger for the low temperature heat source and the heat exchanger for the most upstream EGR gas. The gist of the present invention is that it further includes a distribution order changing means for changing.

  For example, the flow order of the working fluid is changed in the order of the heat exchanger for the low temperature heat source and the heat exchanger for the most upstream EGR gas by the flow order changing means. As a result, the EGR gas passing through the heat exchanger for the most upstream EGR gas is heat-exchanged with the working fluid whose temperature has been increased by the heat exchange for the low-temperature heat source, so that the EGR gas is supercooled. Can be prevented.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the flow order changing means includes a flow direction of the working fluid flowing through the heat exchanger for the most upstream EGR gas, and the flow for the most upstream EGR gas. The gist is to change the flow order of the working fluid while maintaining the flow direction of the EGR gas flowing through the heat exchanger.

  According to this invention, before and after changing the flow order of the working fluid by the flow order changing means, the flow direction of the working fluid flowing through the heat exchanger for the most upstream EGR gas, and the heat exchanger for the most upstream EGR gas. The flow direction of the EGR gas flowing through is maintained. Therefore, it is possible to prevent the liquid phase region and the gas phase region of the working fluid generated in the heat exchanger for the most upstream EGR gas from being reversed. As a result, it is possible to prevent the heat exchange performance of the heat exchanger for the most upstream EGR gas from fluctuating.

  According to the present invention, the EGR gas can be cooled before being sucked into the engine, and the working fluid can be heated before being sucked into the expander.

The schematic diagram which shows the Rankine-cycle apparatus in 1st Embodiment. The schematic diagram which shows the Rankine-cycle apparatus in 2nd Embodiment. The schematic diagram which shows the Rankine-cycle apparatus in 3rd Embodiment. The schematic diagram which shows the Rankine-cycle apparatus in 4th Embodiment. The schematic diagram which shows the Rankine-cycle apparatus in another embodiment.

(First embodiment)
A first embodiment of the present invention will be described below with reference to FIG. The Rankine cycle device is mounted on the vehicle.

  As shown in FIG. 1, the Rankine cycle apparatus 10 includes an expander 20, a condenser 30, a pump 40, a first EGR gas heat exchanger 51 as an EGR gas heat exchanger, a low temperature heat source heat exchanger 53, and an EGR. A refrigerant circulation circuit 11 is provided as a working fluid circuit formed by sequentially connecting a second EGR gas heat exchanger 52 as a gas heat exchanger. In the refrigerant circulation circuit 11, the refrigerant circulates as a working fluid. In the refrigerant circuit 11, the refrigerant is arranged in the order of the expander 20, the condenser 30, the pump 40, the first EGR gas heat exchanger 51, the low-temperature heat source heat exchanger 53, and the second EGR gas heat exchanger 52. The refrigerant flows along the refrigerant circulation circuit 11.

  The outlet of the pump 40 and the first EGR gas heat exchanger 51 are connected via the first passage 21. The first EGR gas heat exchanger 51 and the low temperature heat source heat exchanger 53 are connected via the second passage 22. The low-temperature heat source heat exchanger 53 and the second EGR gas heat exchanger 52 are connected via the third passage 23. The second EGR gas heat exchanger 52 and the inlet of the expander 20 are connected via a fourth passage 24. The outlet of the expander 20 and the inlet of the condenser 30 are connected via a fifth passage 25. The outlet of the condenser 30 and the inlet of the pump 40 are connected via a sixth passage 26. Therefore, in the refrigerant circuit 11, the first EGR gas heat exchanger 51, the low-temperature heat source heat exchanger 53, and the second EGR gas heat exchanger 52 are connected in series from the outlet of the pump 40 to the inlet of the expander 20. It is connected.

  The first EGR gas heat exchanger 51 corresponds to the most upstream EGR gas heat exchanger disposed at the most upstream position in the refrigerant flow direction from the outlet of the pump 40 to the inlet of the expander 20. The second EGR gas heat exchanger 52 corresponds to the most downstream EGR gas heat exchanger arranged at the most downstream position in the refrigerant flow direction from the outlet of the pump 40 to the inlet of the expander 20. The first EGR gas heat exchanger 51 and the second EGR gas heat exchanger 52 cause the refrigerant pumped by the pump 40 to exchange heat with EGR gas that is part of the exhaust gas exhausted from the engine 61. The low-temperature heat source heat exchanger 53 causes the refrigerant to exchange heat with engine coolant, which is a heat source that is at a lower temperature than the temperature of the EGR gas. In the present embodiment, the engine 61 is a diesel engine.

  An intake passage 62 is connected to the engine 61. In the intake passage 62, a compressor 63a of the supercharger 63 is provided. An exhaust passage 64 is connected to the engine 61. In the exhaust passage 64, a turbine 63b of the supercharger 63 is provided. The supercharger 63 is a known variable nozzle turbocharger that is operated by an exhaust flow. The variable nozzle type turbocharger drives the compressor 63a using the rotational torque generated in the turbine 63b by the action of the exhaust flow as a drive source, and pumps the intake air. The intake passage 62 is provided with an intercooler 62a downstream of the supercharger 63 in the air flow direction. The intercooler 62a cools the intake air whose temperature has increased due to supercharging of the supercharger 63.

  The exhaust passage 64 is formed with an EGR passage 65 that recirculates EGR gas, which is part of the exhaust gas exhausted from the engine 61, to the intake passage 62. The EGR passage 65 is a part of the exhaust passage 64. One end of the EGR passage 65 is connected to the upstream side of the supercharger 63 in the exhaust gas flow direction, and the other end of the EGR passage 65 is connected to the intake passage 62. A first EGR gas heat exchanger 51 and a second EGR gas heat exchanger 52 are disposed in the EGR passage 65. Then, the EGR gas flowing through the EGR passage 65 flows in the order of the second EGR gas heat exchanger 52 and the first EGR gas heat exchanger 51. That is, the most upstream EGR gas in the flow direction of the EGR gas flows into the second EGR gas heat exchanger 52, and the most downstream EGR gas in the flow direction of the EGR gas flows into the first EGR gas heat exchanger 51. Flows in. The EGR passage 65 is provided with an EGR valve 65a on the downstream side of the first EGR gas heat exchanger 51 in the EGR gas flow direction. The recirculation amount of the EGR gas to the intake passage 62 is adjusted by the EGR valve 65a.

Next, the operation of the first embodiment will be described.
When the pump 40 is driven, the refrigerant is pumped by the driving of the pump 40 and the refrigerant circulates through the refrigerant circulation circuit 11. Further, the EGR gas flows through the EGR passage 65 by driving the engine 61. The EGR gas that passes through the second EGR gas heat exchanger 52 is heat-exchanged with the refrigerant whose temperature has been increased by heat exchange in the low-temperature heat source heat exchanger 53, and then in the first EGR gas heat exchanger 51. Since the heat is exchanged with the low-temperature refrigerant immediately after being pumped from the pump 40, the EGR gas is sufficiently cooled before being sucked into the engine 61. Then, the cooled EGR gas is recirculated to the intake passage 62 and mixed with the intake air to be taken into the engine 61 again.

  Further, for example, when the refrigerant passing through the first EGR gas heat exchanger 51 is heated by heat exchange with the EGR gas, the temperature is lowered by heat exchange in the low temperature heat source heat exchanger 53. However, since heat is exchanged with the EGR gas in the second EGR gas heat exchanger 52, the refrigerant is sufficiently heated before being sucked into the expander 20. The heated refrigerant is sucked into the expander 20 through the fourth passage 24 and expanded in the expander 20, whereby a part of the heat quantity of the refrigerant is taken out as mechanical energy in the expander 20. . The mechanical energy thus taken out generates power by a generator (not shown), assists the torque of the engine 61, and the like. Further, the refrigerant that has been expanded by the expander 20 and has been cooled and depressurized is sucked into the condenser 30 via the fifth passage 25. The refrigerant sucked into the condenser 30 is condensed by the condenser 30 and changed into a liquid refrigerant, and the liquid refrigerant is sucked into the pump 40 through the sixth passage 26.

In the first embodiment, the following effects can be obtained.
(1) In the refrigerant circulation circuit 11, the first EGR gas heat exchanger 51, the low-temperature heat source heat exchanger 53, and the second EGR gas heat exchanger 52 are connected between the outlet of the pump 40 and the inlet of the expander 20. Connected in series. Further, the most upstream EGR gas in the flow direction of the EGR gas flows into the second EGR gas heat exchanger 52, and the most downstream EGR gas in the flow direction of the EGR gas flows into the first EGR gas heat exchanger 51. Flows in. Therefore, the EGR gas passing through the second EGR gas heat exchanger 52 is heat-exchanged with the refrigerant whose temperature has been increased by the heat exchange in the low-temperature heat source heat exchanger 53, and then the first EGR gas heat exchanger. In 51, heat exchange is performed with the low-temperature refrigerant immediately after being pumped from the pump 40, so that the EGR gas can be sufficiently cooled before being sucked into the engine 61. In addition, after the refrigerant passing through the first EGR gas heat exchanger 51 is heated by heat exchange with the EGR gas, the temperature may decrease due to heat exchange in the low-temperature heat source heat exchanger 53. However, since heat is exchanged with the EGR gas in the second EGR gas heat exchanger 52 thereafter, the refrigerant can be sufficiently heated before being sucked into the expander 20.

(Second Embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. In the embodiment described below, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the redundant description thereof is omitted or simplified.

  As shown in FIG. 2, the refrigerant circulation circuit 11 is provided with a refrigerant bypass passage 71 as a working fluid bypass passage that bypasses the first EGR gas heat exchanger 51. One end of the refrigerant bypass passage 71 is connected to the first passage 21 via a refrigerant flow rate adjustment valve 71a as a flow rate changing means for changing the flow rate of the refrigerant flowing to the refrigerant bypass passage 71 and the first EGR gas heat exchanger 51. The other end is connected to the second passage 22. The refrigerant flow rate adjusting valve 71a can adjust the flow rate of the refrigerant flowing to the refrigerant bypass passage 71 and the flow rate of the refrigerant flowing to the first EGR gas heat exchanger 51.

  In the EGR passage 65, an EGR gas temperature detection sensor 72 that detects the temperature of the EGR gas that has passed through the first EGR gas heat exchanger 51 on the downstream side of the first EGR gas heat exchanger 51 in the EGR gas flow direction. Is provided. The EGR gas temperature detection sensor 72 is signal-connected to the control unit S. The detection result detected by the EGR gas temperature detection sensor 72 is sent to the control unit S.

Next, the operation of the second embodiment will be described.
When the temperature of the EGR gas detected by the EGR gas temperature detection sensor 72 is higher than a predetermined temperature, the control unit S controls the first EGR gas heat exchanger 51 more than the flow rate of the refrigerant flowing into the refrigerant bypass passage 71. The opening degree of the refrigerant flow rate adjustment valve 71a is adjusted so that the flow rate of the refrigerant flowing to the flow rate increases. According to this, as in the first embodiment, the EGR gas is heat-exchanged with the refrigerant immediately after being pumped from the pump 40 in the first EGR gas heat exchanger 51, and thus is sucked into the engine 61. Fully cooled before.

  When the output of the engine 61 is low and the temperature of the EGR gas detected by the EGR gas temperature detection sensor 72 is lower than a predetermined temperature, the control unit S has a value higher than the flow rate of the refrigerant flowing into the refrigerant bypass passage 71. The opening degree of the refrigerant flow rate adjustment valve 71a is adjusted so that the flow rate of the refrigerant flowing to the 1EGR gas heat exchanger 51 is reduced. Thus, by changing the flow rate of the refrigerant flowing to the refrigerant bypass passage 71 and the first EGR gas heat exchanger 51, the amount of heat that the EGR gas is deprived by the refrigerant in the first EGR gas heat exchanger 51 is reduced. It is prevented that the temperature of the EGR gas becomes too lower than the predetermined temperature.

  Therefore, the temperature of the EGR gas becomes too low, and the water contained in the EGR gas is condensed and reacts with the sulfur oxide (SOx), so that sulfuric acid is generated. The sulfuric acid causes the EGR passage 65 in which the EGR gas flows. The component parts are prevented from deteriorating. Here, the “predetermined temperature” refers to a temperature at which moisture contained in the EGR gas begins to condense, and the “predetermined temperature” refers to a temperature at which the moisture contained in the EGR gas begins to condense. Refers to a slightly higher temperature.

Therefore, according to the second embodiment, in addition to the same effect as the effect (1) of the first embodiment, the following effects can be obtained.
(2) Refrigerant flow rate for changing the flow rate of the refrigerant flowing into the refrigerant circulation circuit 11 to the refrigerant bypass passage 71 that bypasses the first EGR gas heat exchanger 51, the refrigerant bypass passage 71, and the first EGR gas heat exchanger 51 An adjustment valve 71a is provided. Then, the flow rate of the refrigerant flowing to the first EGR gas heat exchanger 51 is made smaller than the flow rate of the refrigerant flowing to the refrigerant bypass passage 71 by the refrigerant flow rate adjusting valve 71a. As a result, the amount of heat taken by the EGR gas by the refrigerant in the first EGR gas heat exchanger 51 is reduced, and the EGR gas can be prevented from being overcooled. Therefore, the temperature of the EGR gas becomes too low, and the water contained in the EGR gas is condensed and reacts with the sulfur oxide (SOx), so that sulfuric acid is generated. The sulfuric acid causes the EGR passage 65 in which the EGR gas flows. It is possible to prevent the component parts from deteriorating. As a result, it is possible to prevent a problem from occurring in the performance of the engine 61 due to the deterioration of the components of the EGR passage 65.

  (3) In the present embodiment, the engine 61 is a diesel engine. Compared to gasoline engines, diesel engines contain a lot of sulfur in the exhaust gas, so when the temperature of the EGR gas becomes too low and the moisture contained in the EGR gas condenses, the sulfur and condensed water react. As a result, sulfuric acid is easily generated. However, in this embodiment, since it is possible to prevent the temperature of the EGR gas from becoming too low, sulfuric acid is generated by the condensation of water contained in the EGR gas and reaction with sulfur oxide in the diesel engine. And it can prevent that the component of the EGR path 65 deteriorates.

(Third embodiment)
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. In the embodiments described below, the same components as those in the first and second embodiments already described are denoted by the same reference numerals, and the redundant description thereof is omitted or simplified.

  As shown in FIG. 3, the refrigerant circulation circuit 11 is provided with a first communication passage 81 having one end connected to the first passage 21 via the switching valve 81a and the other end connected to the third passage 23. Has been. The switching valve 81a includes a flow of the refrigerant pumped to the first passage 21 by the pump 40 toward the first EGR gas heat exchanger 51 via the first passage 21, the first passage 21, and the first passage. The flow can be switched to the flow flowing toward the third passage 23 via the communication passage 81.

  In the third passage 23, the first on-off valve V <b> 1 is disposed closer to the second EGR gas heat exchanger 52 than the portion where the other end of the first communication passage 81 is connected. And if the 1st on-off valve V1 opens, the flow of the refrigerant | coolant which flows into the heat exchanger 52 side for 2nd EGR gas from the heat exchanger 53 side for low temperature heat sources will be accept | permitted. When the first on-off valve V1 is closed, the flow of the refrigerant flowing from the low-temperature heat source heat exchanger 53 side to the second EGR gas heat exchanger 52 side is restricted, and the second EGR gas heat exchanger 52 side The flow of the refrigerant flowing from the low temperature heat source heat exchanger 53 to the low temperature heat source 53 side is regulated.

  In the first passage 21, one end of the second communication passage 82 is connected to the first EGR gas heat exchanger 51 side of the switching valve 81a. The other end of the second communication passage 82 is connected to the second EGR gas heat exchanger 52 side with respect to the first on-off valve V1 in the third passage 23. A second open / close valve V <b> 2 is disposed in the second communication passage 82. When the second on-off valve V2 is opened, the flow of the refrigerant flowing from the first passage 21 to the third passage 23 side through the second communication passage 82 is allowed. Further, when the second on-off valve V2 is closed, the flow of the refrigerant flowing from the first passage 21 to the third passage 23 side via the second communication passage 82 is restricted.

Next, the operation of the third embodiment will be described.
When the temperature of the EGR gas detected by the EGR gas temperature detection sensor 72 is higher than a predetermined temperature, the control unit S causes the refrigerant pumped to the first passage 21 by the pump 40 to pass through the first passage 21. The switching valve 81a is switched so as to flow to the first EGR gas heat exchanger 51. Further, the control unit S opens the first on-off valve V1 and closes the second on-off valve V2. Then, the refrigerant pumped to the first passage 21 by the pump 40 is converted into the first EGR gas heat exchanger 51, the second passage 22, the low temperature heat source heat exchanger 53, the third passage 23, and the second EGR gas heat exchanger. It flows in the order of 52. According to this, similarly to the first embodiment, the EGR gas is heat-exchanged with the low-temperature refrigerant immediately after being pumped from the pump 40 in the first EGR gas heat exchanger 51, so that the intake air is sucked into the engine 61. The EGR gas is sufficiently cooled before being done. In addition, the refrigerant | coolant which is going to flow out into the 1st channel | path 21 from the 3rd channel | path 23 via the 1st communication channel | path 81 is controlled by the switching valve 81a. Further, the refrigerant that is about to flow out from the third passage 23 to the first passage 21 via the second communication passage 82 is regulated by the second on-off valve V2.

  When the output of the engine 61 is low and the temperature of the EGR gas detected by the EGR gas temperature detection sensor 72 is lower than a predetermined temperature, the control unit S sends the refrigerant pumped to the first passage 21 by the pump 40. However, the switching valve 81 a is switched so as to flow into the third passage 23 through the first passage 21 and the first communication passage 81. Further, the control unit S closes the first on-off valve V1 and opens the second on-off valve V2. Then, the refrigerant pressure-fed to the first passage 21 by the pump 40 includes the first communication passage 81, the third passage 23, the low-temperature heat source heat exchanger 53, the second passage 22, the first EGR gas heat exchanger 51, The first passage 21, the second communication passage 82, the third passage 23, and the second EGR gas heat exchanger 52 flow in this order. That is, the refrigerant circulation order is changed so that the low-temperature heat source heat exchanger 53 and the first EGR gas heat exchanger 51 flow in this order. Therefore, in the third embodiment, the first communication passage 81, the switching valve 81a, the second communication passage 82, the first on-off valve V1, and the second on-off valve V2 use the heat exchange for the low-temperature heat source in the refrigerant circuit 11. The flow order changing means for changing the flow order of the refrigerant to the heat exchanger 53 and the first EGR gas heat exchanger 51 is formed.

  As a result, the EGR gas passing through the first EGR gas heat exchanger 51 is heat-exchanged with the refrigerant whose temperature has been increased by exchanging heat with the engine coolant in the low-temperature heat source heat exchanger 53. The 1EGR gas heat exchanger 51 is prevented from being overcooled.

Therefore, according to the third embodiment, in addition to the effect (1) of the first embodiment and the effect (3) of the second embodiment, the following effects can be obtained. .
(4) The refrigerant circulation circuit 11 is formed by the first communication passage 81, the switching valve 81a, the second communication passage 82, the first on-off valve V1, and the second on-off valve V2, and the low-temperature heat source heat exchanger 53 and the second on-off valve V2. The flow order changing means for changing the flow order of the refrigerant to the 1 EGR gas heat exchanger 51 is provided. Then, the flow order of the refrigerant is changed to the low-temperature heat source heat exchanger 53 and the first EGR gas heat exchanger 51 by the flow order changing means. As a result, the EGR gas passing through the first EGR gas heat exchanger 51 is heat-exchanged with the refrigerant whose temperature has been increased due to heat exchange with the engine coolant in the low-temperature heat source heat exchanger 53, so that the EGR gas is excessive. It is possible to prevent cooling.

  (5) According to the third embodiment, since the first EGR gas heat exchanger 51 is not bypassed, the first EGR gas heat exchanger 51 can be used effectively. In addition, if the first EGR gas heat exchanger 51 is bypassed, the flow of the refrigerant passing through the first EGR gas heat exchanger 51 is lost, and the refrigerant may remain in the first EGR gas heat exchanger 51. There is. If the refrigerant is retained in the first EGR gas heat exchanger 51, the accumulated refrigerant is excessively heated by the EGR gas passing through the first EGR gas heat exchanger 51, and the refrigerant is thermally decomposed to generate an acid such as hydrofluoric acid. This causes problems such as deterioration of the components of the first EGR gas heat exchanger 51 due to this acid, or thermal decomposition of the lubricating oil circulating in the refrigerant circuit 11 together with the refrigerant, and carbonization of the lubricating oil. Arise. However, according to the present embodiment, the refrigerant does not stay in the first EGR gas heat exchanger 51, and it is possible to prevent the first EGR gas heat exchanger 51 from being defective.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG. In the embodiments described below, the same components as those in the first and second embodiments already described are denoted by the same reference numerals, and the redundant description thereof is omitted or simplified.

  As shown in FIG. 4, the refrigerant circulation circuit 11 is provided with a first communication passage 91 having one end connected to the first passage 21 via the switching valve 91a and the other end connected to the second passage 22. Has been. The switching valve 91a includes a flow of the refrigerant pumped to the first passage 21 by the pump 40, a flow of the refrigerant flowing to the first EGR gas heat exchanger 51 through the first passage 21, and the first passage 21 and the first communication passage. The flow can be switched to the flow through the second passage 22 via 91.

  In the 2nd channel | path 22, the 1st on-off valve V11 is arrange | positioned in the 1st EGR gas heat exchanger 51 side rather than the location where the other end of the 1st communication channel | path 91 was connected. When the first on-off valve V11 is opened, the flow of the refrigerant flowing from the first EGR gas heat exchanger 51 side to the low temperature heat source heat exchanger 53 side is allowed. Further, when the first on-off valve V1 is closed, the flow of the refrigerant flowing from the first EGR gas heat exchanger 51 side to the low temperature heat source heat exchanger 53 side is restricted, and from the low temperature heat source heat exchanger 53 side. The flow of the refrigerant flowing toward the first EGR gas heat exchanger 51 side is restricted.

  In the first passage 21, one end of the second communication passage 92 is connected to the first EGR gas heat exchanger 51 side of the switching valve 91a. The other end of the second communication passage 92 is connected to the third passage 23. A second on-off valve V12 is disposed in the second communication passage 92. When the second on-off valve V12 is opened, the refrigerant flow through the second communication passage 92 between the first passage 21 and the third passage 23 is allowed. Further, when the second on-off valve V12 is closed, the flow of the refrigerant through the second communication passage 92 between the first passage 21 and the third passage 23 is restricted.

  In the 3rd channel | path 23, the 3rd on-off valve V13 is arrange | positioned at the 2nd EGR gas heat exchanger 52 side rather than the location where the other end of the 2nd communication channel | path 92 was connected. When the third on-off valve V13 is opened, the refrigerant flowing from the low-temperature heat source heat exchanger 53 side to the second EGR gas heat exchanger 52 side is allowed. Further, when the third on-off valve V13 is closed, the flow of the refrigerant flowing from the low-temperature heat source heat exchanger 53 side to the second EGR gas heat exchanger 52 side is restricted, and the second EGR gas heat exchanger 52 side The flow of the refrigerant flowing from the low temperature heat source heat exchanger 53 to the low temperature heat source 53 side is regulated.

  In the second passage 22, one end of the third communication passage 93 is connected to the first EGR gas heat exchanger 51 side of the first on-off valve V <b> 11. The other end of the third communication passage 93 is connected to the second EGR gas heat exchanger 52 side with respect to the third on-off valve V13 in the third passage 23. A fourth open / close valve V <b> 14 is disposed in the third communication passage 93. When the fourth on-off valve V14 is opened, the refrigerant flow through the third communication passage 93 between the second passage 22 and the third passage 23 is allowed. Further, when the fourth on-off valve V14 is closed, the flow of the refrigerant through the third communication passage 93 between the second passage 22 and the third passage 23 is restricted.

Next, the operation of the fourth embodiment will be described.
When the temperature of the EGR gas detected by the EGR gas temperature detection sensor 72 is higher than a predetermined temperature, the control unit S causes the refrigerant pumped to the first passage 21 by the pump 40 to pass through the first passage 21. The switching valve 91a is switched so as to flow to the first EGR gas heat exchanger 51. Further, the control unit S opens the first on-off valve V11 and the third on-off valve V13, and closes the second on-off valve V12 and the fourth on-off valve V14. Then, the refrigerant pumped to the first passage 21 by the pump 40 is converted into the first EGR gas heat exchanger 51, the second passage 22, the low temperature heat source heat exchanger 53, the third passage 23, and the second EGR gas heat exchanger. It flows in the order of 52. According to this, similarly to the first embodiment, the EGR gas is heat-exchanged with the low-temperature refrigerant immediately after being pumped from the pump 40 in the first EGR gas heat exchanger 51, so that the intake air is sucked into the engine 61. The EGR gas is sufficiently cooled before being done.

  When the output of the engine 61 is low and the temperature of the EGR gas detected by the EGR gas temperature detection sensor 72 is lower than a predetermined temperature, the control unit S sends the refrigerant pumped to the first passage 21 by the pump 40. However, the switching valve 91a is switched so as to flow into the second passage 22 through the first passage 21 and the first communication passage 91. Further, the control unit S closes the first on-off valve V11 and the third on-off valve V13, and opens the second on-off valve V12 and the fourth on-off valve V14. Then, the refrigerant pressure-fed to the first passage 21 by the pump 40 is the first communication passage 91, the second passage 22, the low-temperature heat source heat exchanger 53, the third passage 23, the second communication passage 92, and the first passage 21. The first EGR gas heat exchanger 51, the second passage 22, the third communication passage 93, the third passage 23, and the second EGR gas heat exchanger 52 flow in this order. That is, the refrigerant circulation order is changed so that the low-temperature heat source heat exchanger 53 and the first EGR gas heat exchanger 51 flow in this order. Therefore, in the fourth embodiment, the first communication passage 91, the switching valve 91a, the second communication passage 92, the third communication passage 93, the first on-off valve V11, the second on-off valve V12, the third on-off valve V13, and the first The 4 on-off valve V14 forms a flow order changing means for changing the flow order of the refrigerant to the low temperature heat source heat exchanger 53 and the first EGR gas heat exchanger 51 in the refrigerant circulation circuit 11.

  As a result, the EGR gas passing through the first EGR gas heat exchanger 51 is heat-exchanged with the refrigerant whose temperature has been increased by exchanging heat with the engine coolant in the low-temperature heat source heat exchanger 53. The 1EGR gas heat exchanger 51 is prevented from being overcooled.

  In the fourth embodiment, the refrigerant flow order is maintained while maintaining the flow direction of the refrigerant flowing through the first EGR gas heat exchanger 51 and the flow direction of the EGR gas flowing through the first EGR gas heat exchanger 51. The heat exchanger 53 for the low temperature heat source and the heat exchanger 51 for the first EGR gas are changed in this order. Therefore, the liquid phase region and the gas phase region of the refrigerant generated in the first EGR gas heat exchanger 51 are reversed before and after the refrigerant circulation order is changed by the circulation order changing unit. The heat exchange performance in the first EGR gas heat exchanger 51 does not fluctuate.

  Therefore, according to the fourth embodiment, the effect (1) of the first embodiment, the effect (3) of the second embodiment, and the same effects as those of the third embodiment (4) and (5) In addition, the following effects can be obtained.

  (6) In the refrigerant circuit 11, the first communication passage 91, the switching valve 91a, the second communication passage 92, the third communication passage 93, the first on-off valve V11, the second on-off valve V12, the third on-off valve V13, and the second A flow order changing means is provided which is formed by the four on-off valve V14 and changes the flow order of the refrigerant to the low temperature heat source heat exchanger 53 and the first EGR gas heat exchanger 51. Then, the distribution order of the refrigerant is changed while maintaining the distribution direction of the refrigerant flowing through the first EGR gas heat exchanger 51 and the distribution direction of the EGR gas flowing through the first EGR gas heat exchanger 51 by the distribution order changing means. It changed so that it might become the order of the heat exchanger 53 for low temperature heat sources, and the heat exchanger 51 for 1st EGR gas. Therefore, the liquid phase region and the gas phase region of the refrigerant generated in the first EGR gas heat exchanger 51 are not reversed, and the heat exchange performance in the first EGR gas heat exchanger 51 varies. Can be prevented.

In addition, you may change the said embodiment as follows.
As shown in FIG. 5, the first EGR gas heat exchanger 51 and the second EGR gas heat exchanger 52 may be integrated. According to this, the site | part which connects the heat exchanger 51 for 1st EGR gas and the heat exchanger 52 for 2nd EGR gas in the EGR channel | path 65 can be deleted, and a number of parts can be reduced.

  In each of the above embodiments, the EGR gas flowing through the first EGR gas heat exchanger 51, the second EGR gas heat exchanger 52, or the low temperature heat source heat exchanger 53, the engine cooling water, or the flow type of the refrigerant is, for example, The present invention is not limited to the flow type such as the counter flow, but is effective for other flow types (for example, parallel flow, cross flow, etc.).

In each of the above embodiments, the number of EGR gas heat exchangers that exchange heat between the refrigerant and the EGR gas may be increased.
In the above embodiments, the number of low-temperature heat source heat exchangers may be two or more.

  In the second embodiment, the flow rate changing means may be a switching valve that switches the flow of the refrigerant to the flow to the refrigerant bypass passage 71 or the flow to the first EGR gas heat exchanger 51. Then, the refrigerant flow is switched to the flow to the refrigerant bypass passage 71 or the flow to the first EGR gas heat exchanger 51 by the switching valve, whereby the refrigerant bypass passage 71 and the first EGR gas heat exchanger 51 are switched. You may make it change the flow volume of the refrigerant | coolant which flows into.

  In each of the above embodiments, as the heat source of the heat exchanger 53 for the low-temperature heat source, for example, exhaust gas after passing through the exhaust purification catalyst, intake air whose temperature has been increased by supercharging of the supercharger 63, or the like may be used. Good. In short, the heat source of the heat exchanger 53 for a low-temperature heat source may be a heat source having a temperature lower than the temperature of the EGR gas.

In each of the above embodiments, the working fluid may be water, for example.
In each of the above embodiments, the engine 61 may be a gasoline engine.
Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.

  (A) The Rankine cycle device according to any one of claims 1 to 4, wherein the engine is a diesel engine.

  DESCRIPTION OF SYMBOLS 10 ... Rankine-cycle apparatus, 11 ... Refrigerant circulation circuit as a working fluid circuit, 20 ... Expander, 30 ... Condenser, 40 ... Pump, 51 ... Heat exchanger for uppermost EGR gas in EGR gas heat exchanger A first EGR gas heat exchanger corresponding to E52, a second EGR gas heat exchanger corresponding to the most downstream EGR gas heat exchanger of the EGR gas heat exchangers, 53 a low temperature heat source heat exchanger, DESCRIPTION OF SYMBOLS 61 ... Engine, 65 ... EGR passage, 71 ... Refrigerant bypass passage as working fluid bypass passage, 71a ... Refrigerant flow rate adjustment valve as flow rate change means, 81, 91 ... First communication passage forming flow order change means, 81a 91a, a switching valve that forms a flow order changing means, 82, 92, a second communication passage that forms a flow order changing means, 93, a third communication path that forms a flow order changing means, V1 V11: a first on-off valve that forms a flow order changing means, V2, V12: a second on-off valve that forms a flow order changing means, V13: a third on-off valve that forms a flow order changing means, V14: a flow order changing means 4th on-off valve which forms.

Claims (4)

A pump for pumping the working fluid;
A plurality of EGR gas heat exchangers that exchange heat between the working fluid pumped by the pump and EGR gas exhausted from the engine;
At least one heat exchanger for a low-temperature heat source that exchanges heat between the heat source that is lower in temperature than the temperature of the EGR gas and the working fluid;
An expander that outputs mechanical energy by expanding the working fluid heat-exchanged in the plurality of EGR gas heat exchangers and the low-temperature heat source heat exchanger;
A working fluid circuit is formed from a condenser for condensing the working fluid expanded by the expander,
Each EGR gas heat exchanger and low-temperature heat source heat exchanger are connected in series from the outlet of the pump to the inlet of the expander,
The most upstream EGR gas heat exchanger, which is one of the plurality of EGR gas heat exchangers, is arranged in the most upstream flow direction of the working fluid from the pump outlet to the expander inlet. As
The most downstream EGR gas heat exchanger, which is one of the plurality of EGR gas heat exchangers, is arranged at the most downstream in the flow direction of the working fluid from the outlet of the pump to the inlet of the expander. Has been
The most upstream EGR gas in the flow direction of the EGR gas flows into the heat exchanger for the most downstream EGR gas, and the most downstream EGR gas in the flow direction of the EGR gas flows into the heat exchanger for the most upstream EGR gas. A Rankine cycle device in which EGR gas flows.   In the working fluid circuit, the flow rate of the working fluid that flows to the working fluid bypass passage that bypasses the heat exchanger for the most upstream EGR gas, the working fluid bypass passage, and the heat exchanger for the most upstream EGR gas is changed. The Rankine cycle apparatus according to claim 1, further comprising a flow rate changing unit.   The working fluid circuit further comprises a flow order changing means for changing a flow order of the working fluid to the heat exchanger for the low-temperature heat source and the heat exchanger for the most upstream EGR gas. The Rankine cycle apparatus according to 1.   The flow order changing means maintains the flow direction of the working fluid flowing through the heat exchanger for the most upstream EGR gas and the flow direction of EGR gas flowing through the heat exchanger for the most upstream EGR gas. The Rankine cycle apparatus according to claim 3, wherein the order of distribution of the gas is changed.