JP2010151023A - Rankine cycle system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rankine cycle system capable of efficiently using exhaust heat of an engine without excessively heating a medium. <P>SOLUTION: A rankine cycle system (10) comprises a heat exchanger (12) for evaporating a medium through heat exchange, an expander (13) for generating energy by the evaporated medium, a condenser (14) for condensing the evaporated medium to be liquefied, and a pump (15) for feeding the liquefied medium to the heat exchanger (12). The heat exchanger (12) executes heat exchange by cooling water and exhaust gas of an internal combustion engine (25), and by the cooling water and medium thereafter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a Rankine cycle system that can efficiently use exhaust heat of an engine.

  Conventionally, a Rankine cycle heat engine (Rankine cycle system) is known in which a liquid as a medium is vaporized by heat, and energy is extracted by the vaporized medium. There is also known a system in which this Rankine cycle system is mounted on a vehicle and energy is extracted using exhaust heat of an internal combustion engine.

  As the exhaust heat of the internal combustion engine used in the Rankine cycle system, engine cooling water or the like is generally used, but one that uses high-temperature exhaust gas as an energy source is also known.

As such a Rankine cycle system, a Rankine cycle system (see Patent Document 1) having a heat exchange means for vaporizing a Rankine cycle working medium using the thermal energy of EGR gas is known.
JP 2007-239513 A

  As described in Patent Document 1, it is known to use exhaust gas from an internal combustion engine as a heat source for a Rankine cycle system. However, although HFC is widely used as a medium used in the Rankine cycle system, there is a possibility of causing thermal decomposition due to the high temperature of the exhaust gas. In addition, the oil used for lubricating the Rankine cycle system may cause carbonization due to heat.

  The present invention has been made in view of such problems, and an object thereof is to provide an exhaust heat recovery system that can efficiently use exhaust heat of an engine without excessively heating a medium. .

  The invention according to claim 1 is an internal combustion engine cooling system that cools heat generated by the internal combustion engine with cooling water, a heat exchanger that vaporizes a medium by heat exchange, and an expansion that generates energy by the vaporized medium. And a Rankine cycle system comprising: a condenser for condensing and liquefying the vaporized medium; and a pump for sending the liquefied medium to the heat exchanger, the heat exchanger comprising: Heat exchange is performed between the cooling water and the exhaust gas of the internal combustion engine, and heat exchange is performed between the cooling water after the heat exchange and the medium.

  According to a second aspect of the present invention, in the exhaust heat recovery system according to the first aspect, the heat exchanger includes a flow path of the medium, a flow path of the cooling water, and a flow path of the exhaust gas. The cooling water flow path is interposed between the flow path of the medium and the flow path of the exhaust gas.

  The invention according to claim 3 is the exhaust heat recovery system according to claim 1, wherein the heat exchanger exchanges heat between the medium and the cooling water, and the cooling water and the exhaust gas after the heat exchange. And heat exchange between the cooling water after the heat exchange and the medium.

According to a fourth aspect of the present invention, in the exhaust heat recovery system according to the third aspect, the heat exchanger is provided with a cooling water flow path through which cooling water flows and a substantially right angle in the cooling water flow path. 1 medium flow path, an exhaust gas flow path, and a second medium flow path, wherein the first medium flow path and the second medium flow path are connected by a U-turn path, and the cooling water is Circulates around the first medium flow path, then circulates around the second medium flow path through the periphery of the exhaust gas flow path, and the medium circulates through the first medium flow path. Then, it flows through the U-turn passage to the second medium flow path.

  According to a fifth aspect of the present invention, in the exhaust heat recovery system according to the third aspect, the heat exchanger includes a first cooling water channel and a second cooling water channel through which cooling water flows, and the first A first medium flow path and a first exhaust gas flow path provided substantially orthogonally in the cooling water flow path, and a second exhaust gas flow path provided substantially orthogonally in the second cooling water flow path. And the second medium flow path, the first cooling water flow path and the second cooling water flow path being connected by a U-turn path, and the first medium flow path and the second medium. The flow path is connected by a U-turn path, the first exhaust gas flow path and the second exhaust gas flow path are connected by a U-turn path, and the cooling water is in the first cooling water flow path. , After circulating around the first medium flow path and the first exhaust gas flow path, through the U-turn path, The exhaust gas flow path and the second medium flow path are circulated, and the medium flows through the first medium flow path and then passes through the U-turn path to the second medium flow path. The exhaust gas flows through the first exhaust gas flow path, and then flows through the U-turn path to the second exhaust gas flow path.

  According to a sixth aspect of the present invention, in the exhaust heat recovery system according to any one of the first to fifth aspects, the exhaust gas after heat exchange in the heat exchanger is circulated to an intake system of the internal combustion engine. It is characterized by being.

  According to a seventh aspect of the present invention, in the exhaust heat recovery system according to any one of the first to fifth aspects, an exhaust gas recovery valve that causes the exhaust gas to flow through the heat exchanger, and cooling water is supplied to the heat exchanger. And a control device for controlling the cooling water recovery valve to be circulated, the exhaust gas recovery valve, and the cooling water recovery valve, and the control device is configured to control the exhaust gas recovery valve when the internal combustion engine is started. And the cooling water recovery valve is controlled to flow the cooling water and the exhaust gas through the heat exchanger, and when the temperature of the cooling water flowing out of the heat exchanger exceeds a predetermined temperature, the exhaust gas recovery valve is Control to stop the flow of the exhaust gas to the heat exchanger, and when the temperature of the medium flowing out from the heat exchanger exceeds a predetermined temperature, or the pressure of the medium flowing out from the heat exchanger is a predetermined pressure When it exceeds controls the cooling water recovery valve, characterized in that stopping the flow of the cooling water to the heat exchanger.

  According to the invention described in claim 1, in the heat exchanger, heat exchange is performed between the cooling water and the exhaust gas of the engine, and further, heat exchange is performed between the cooling water and the medium after the heat exchange. Heat exchange can be performed without direct contact with the medium, the medium can be prevented from thermal decomposition, and the temperature of the medium can be increased efficiently.

  According to the second aspect of the present invention, the heat exchanger is configured by laminating a flow path of the medium, a flow path of the cooling water, and a flow path of the exhaust gas in multiple layers. Since the flow path of the cooling water is interposed between the path and the medium, the temperature of the medium can be efficiently increased while preventing the medium from being thermally decomposed. Moreover, a heat exchanger can be comprised compactly and space efficiency can be improved.

According to the invention of claim 3, in the heat exchanger, heat exchange is performed between the medium and the cooling water, heat exchange is performed between the cooling water and the exhaust gas after the heat exchange, and further, the cooling water and the medium after the heat exchange are performed. Since heat exchange is performed, heat exchange can be performed without direct contact between the high-temperature exhaust gas and the medium, preventing the medium from being thermally decomposed and increasing the temperature of the medium efficiently.

  According to the invention of claim 4, the cooling water circulates around the first medium flow path, then circulates around the exhaust gas flow path and around the second medium flow path. After passing through the medium flow path, it passes through the U-turn passage to the second medium flow path, so that heat exchange can be performed without direct contact between the high-temperature exhaust gas and the medium, and the medium is thermally decomposed. Can be prevented. Furthermore, the temperature of the medium can be increased efficiently without increasing the size of the heat exchanger.

  According to the invention of claim 5, the cooling water flows around the first medium flow path and the first exhaust gas flow path in the first cooling water flow path, and then passes through the U-turn path to the second exhaust gas. The medium flows around the flow path and the second medium flow path, and the medium flows through the first medium flow path, and then flows through the U-turn path to the second medium flow path. After flowing through the exhaust gas flow path of 1, it flows through the U-turn path to the second exhaust gas flow path, so that heat exchange can be performed without direct contact between the hot exhaust gas and the medium, and the medium is thermally decomposed. This can be prevented. Furthermore, the temperature of the medium can be increased efficiently without increasing the size of the heat exchanger.

  According to the invention described in claim 6, since the exhaust gas after the heat exchange in the heat exchanger is circulated to the intake system of the internal combustion engine, the medium temperature is raised in the heat exchanger and the exhaust gas is used for the EGR system. The exhaust gas temperature produced can be lowered.

  According to the seventh aspect of the present invention, the control device controls the exhaust gas recovery valve and the cooling water recovery valve according to the temperature of the cooling water, the temperature of the medium, and the pressure of the medium, so that the heat exchanger is not increased in size. Thus, the temperature of the medium can be appropriately raised efficiently.

  Hereinafter, an exhaust heat recovery system according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an explanatory diagram of an exhaust heat recovery system according to an embodiment of the present invention.

  The exhaust heat recovery system includes an engine cooling system 20 centered on the engine 25 and a Rankine cycle system 10 that generates energy by exhaust heat of the engine 25 or the like.

  The Rankine cycle system 10 generates rotational energy by the medium path 11 through which the medium circulates, the evaporator 12 as a heat exchanger that vaporizes the medium by exchanging heat by exhaust heat of the vehicle, and the vaporized medium. An expander 13 to be condensed, a condenser 14 to condense and liquefy the vaporized medium, a pump 15 to circulate the liquefied medium, a medium liquefied by the condenser 14 in the medium path 11, and still a gas phase And a liquid tank (L / T) 16 for separating the medium.

  In the present embodiment, HFC-R134a is used as the medium. However, the present invention is not limited to this, and other media may be used.

  The evaporator 12 is configured so that the medium of the Rankine cycle system 10, the cooling water of the engine cooling system 20, and the exhaust gas discharged from the engine 25 flow through the inside thereof. The evaporator 12 raises the temperature of the medium by exchanging heat between them. Details of the heat exchange by the evaporator 12 will be described later.

The expander 13 is rotationally driven by a medium whose volume is expanded by being vaporized by the evaporator 12. The expander 13 shares its rotating shaft with the generator 17. Thereby, the rotational energy of the expander 13 is transmitted to the generator 17, and the generator 17 is generated. The medium is liquefied in the condenser 14 after driving the expander 13, and is circulated through the medium path 11 again by the pump 15.

  The Rankine cycle system 10 according to the present embodiment is configured in this manner, thereby converting thermal energy generated by exhaust heat of the engine 25 into rotational energy, and converting the rotational energy into electrical energy. For example, the electrical energy is stored in a capacitor (not shown). Note that the capacitor is constituted by, for example, a battery or a capacitor.

  An engine cooling system 20 centering on an engine 25 as an internal combustion engine for driving a vehicle is constituted by a cooling water passage 21 through which cooling water circulates. The cooling water path 21 is connected to a radiator 22, a heater core 23, a thermostat (T / S) 24, and a water pump 26.

  The radiator 22 appropriately controls the cooling water temperature by exchanging heat between the cooling water and the atmosphere. The heater core 23 is provided in the vehicle together with other air conditioners, and raises the temperature in the vehicle interior with cooling water. The thermostat 24 switches the cooling water path 21 to the bypass path 27 side when the engine 25 is started, etc., and promotes warm-up of the engine 25. The water pump 26 circulates the cooling water in the cooling water passage 21.

  The engine 25 includes an intake pipe 33 that guides oxygen-containing air into the cylinder chamber, and an exhaust pipe 34 that guides exhaust gas after explosion combustion in the cylinder chamber to the outside of the engine 25.

  The exhaust pipe 34 is provided with an exhaust gas recovery valve 41. One of the exhaust gas recovery valves 41 communicates with the exhaust gas passage 50. The exhaust gas recovery valve 41 is controlled to a recovery mode and a non-recovery mode by the control of the control device 100, and the exhaust gas is circulated to the evaporator 12 via the exhaust gas passage 50 in the recovery mode.

  The exhaust gas guided to the evaporator 12 returns to the exhaust pipe 34 again via the exhaust gas passage 51.

  A distribution valve (cooling water recovery valve) 28 is provided in the middle of the cooling water path 21. The distribution valve 28 is controlled to a recovery mode and a non-recovery mode under the control of the control device 100, and in the recovery mode, cooling water is circulated to the evaporator 12 via the branch path 29.

  The exhaust heat recovery system is provided with a control device 100. The control device 100 measures the medium temperature, medium pressure, and cooling water temperature in the evaporator 12. Further, based on these measured values, the recovery mode and the non-recovery mode of the exhaust gas recovery valve 41 and the distribution valve 28 are controlled.

  Next, the evaporator 12 of the Rankine cycle system 10 will be described.

  The evaporator 12 uses the heat of the exhaust gas discharged from the engine 25 to raise the temperature of the medium of the Rankine cycle system 10 and vaporize the medium.

  Here, since the exhaust gas temperature is high (several hundred degrees Celsius), when the medium of the Rankine cycle system 10 and the high-temperature exhaust gas directly exchange heat, the medium undergoes thermal decomposition, or the circulation path together with the medium. There is a possibility that the oil for lubrication that circulates may cause carbonization.

Therefore, in the present embodiment, the following characteristic configuration is provided so that the exhaust heat can be used efficiently without direct contact between the medium of the Rankine cycle system 10 and the exhaust gas.

  FIG. 2 is a perspective view showing a configuration of the evaporator 12 of the present embodiment.

  The evaporator 12 is a plate stacking type heat exchanger configured by stacking a plurality of plates 120. A medium, cooling water, and exhaust gas are respectively introduced into the evaporator 12 and heat is exchanged between them.

  The evaporator 12 includes three inlets and three outlets corresponding to the medium, cooling water, and exhaust gas. Media is introduced from the media inlet 120a and led out from the media outlet 120b. The cooling water is introduced from the cooling water inlet 121a and led out from the cooling water outlet 121b. The exhaust gas is introduced from the exhaust gas inlet 122a and led out from the exhaust gas outlet 122b.

  FIG. 2B shows a cross-sectional view of the main part of the evaporator 12.

  As shown in FIG. 2 (b), inside the evaporator 12, a medium flow path, a cooling water flow path, and an exhaust gas flow path are stacked in multiple layers. The medium flow path, the cooling water flow path, and the exhaust gas flow path are each configured to be opposed to each other. Still further, the cooling water flow path is always interposed between the medium flow path and the exhaust gas flow path. Thereby, the evaporator 12 is comprised so that heat exchange may be performed, without a medium and waste gas contacting directly.

  FIG. 3 is an explanatory diagram showing the internal structure of the evaporator 12.

  The evaporator 12 is configured by stacking a plurality of plates 120.

  The plate 120 has ribs 125 around it. By laminating the plates 120, a space surrounded by the ribs 125 and the upper and lower plates 120 becomes a flow path through which a medium or the like flows.

  The plate 120 is provided with three inlet-side passages 128 and three outlet-side passages 129.

  One of the inlet-side passages 128 is opened in the plate 120, and the other two communicate with only the inlet passages of the other plates 120 stacked adjacent to each other. This opening becomes the medium inlet 128a. Similarly, any one of the outlet side passages 129 is opened in the plate 120, and this opening portion becomes the outlet 129a of the medium.

  The evaporator 12 is configured by stacking and fixing the plates 120 in multiple layers. The top and bottom portions of the plate 120 have three inlet portions (medium inlet portion 120a, cooling water inlet 121a, exhaust gas inlet 122a) and three outlet portions (medium outlet portion 120b, cooling water outlet 121b, The exhaust gas outlet 122b) is connected.

  With such a structure, the evaporator 12 can increase the medium temperature of the Rankine cycle system 10 using waste heat of exhaust gas.

  In particular, since the cooling water flow path is interposed between the flow path of the medium and the flow path of the exhaust gas, the high temperature of the exhaust gas is not directly transmitted to the medium due to the specific heat of the cooling water, so that the medium is thermally decomposed. Without any problem, the temperature is raised appropriately. In addition, when the cooling water temperature is low, the cooling water temperature is also increased.

  Although not particularly shown in FIG. 3, ribs, fins, or the like may be formed on the inner surface of the plate 120 to rectify the flow of the medium or the like.

  FIG. 4 is a flowchart showing processing of the control device 100 of the present embodiment.

  The control device 100 measures the medium temperature, the medium pressure, and the cooling water temperature in the evaporator 12, and controls the state of the exhaust gas recovery valve 41 and the distribution valve 28, thereby controlling the temperature state of the medium and the Rankine cycle system. Increase the operating efficiency of 10.

  First, the control device 100 determines whether or not the engine 25 has been started (step S10). If the engine 25 has not been started, this process is repeated and waits.

  Next, the control device 100 controls the exhaust gas recovery valve 41 to the recovery mode to make the exhaust pipe 34 and the evaporator 12 communicate with each other. Thereby, exhaust gas is introduce | transduced into the evaporator 12 (step S20).

  Next, the control device 100 controls the distribution valve 28 to the recovery mode to make the cooling water passage 21 and the evaporator 12 communicate with each other. Thereby, cooling water is introduce | transduced into the evaporator 12 (step S30).

  In this state, the medium, the cooling water and the exhaust gas are circulated through the evaporator 12, and heat exchange is performed between them.

  Next, the control device 100 determines whether or not the cooling water temperature at the cooling water outlet 121b of the evaporator 12 is equal to or lower than a predetermined temperature (first predetermined temperature, for example, 100 [° C.]) (step S40). This temperature is a threshold value as to whether the cooling water is not excessively heated by the exhaust gas.

  When it is determined that the cooling water temperature is equal to or lower than the predetermined temperature, the process proceeds to step S60.

  When it is determined that the cooling water temperature exceeds the predetermined temperature, the process proceeds to step S50, and the exhaust gas recovery valve 41 is controlled to the non-recovery mode so that the exhaust gas is not introduced into the evaporator 12.

  In step S50, the control device 100 determines whether or not the medium temperature at the medium outlet 120b of the evaporator 12 is equal to or lower than a predetermined temperature (second predetermined temperature, for example, 95 [° C.]). This temperature is a threshold for whether the medium is not overheated by the cooling water.

  When it is determined that the medium temperature is equal to or lower than the predetermined temperature, the process proceeds to step S70.

  If it is determined that the medium temperature exceeds the predetermined temperature, the process proceeds to step S80.

In step S70, the control device 100 determines whether or not the medium pressure at the medium outlet 120b of the evaporator 12 is equal to or lower than a predetermined pressure (for example, 28 [kg / cm ² (gauge pressure)]). This predetermined pressure is a threshold value as to whether the internal pressure of the Rankine cycle system 10 has increased excessively as a result of the medium being heated to the cooling water.

  When it is determined that the medium pressure is equal to or lower than the predetermined pressure, the process according to this flowchart is terminated and the process proceeds to another process.

  If it is determined that the medium pressure exceeds the predetermined pressure, the process proceeds to step S80.

  In step S <b> 80, the distribution valve 28 is controlled to the non-recovery mode so that the cooling water is not introduced into the evaporator 12. Thereafter, the process according to this flowchart is terminated, and the process proceeds to another process.

  By the treatment as described above, it is possible to appropriately increase the medium temperature using the heat of the exhaust gas, and to suppress an excessive increase in the medium temperature and pressure.

  In particular, the temperature of the medium in the evaporator 12 can be controlled so that the cooling water and the medium are not excessively heated by the high-temperature exhaust gas.

  In addition, the evaporator 12 is not restricted to the above-mentioned structure, Various structures can be used.

  FIG. 5 is an explanatory view showing another configuration of the evaporator 12.

  In the example shown in FIG. 3 and FIG. 4 described above, the evaporator 12 is a plate lamination type. However, in the example shown in FIG. 5, the medium and the exhaust gas path are provided substantially orthogonally in the cooling water atmosphere, Configured to do the exchange.

  As shown in FIG. 5A, the evaporator 12 includes a medium inlet 120a, a medium outlet 120b, a medium U-turn path 120c, a cooling water inlet 121a, a cooling water outlet 121b, an exhaust gas inlet 122a, and an exhaust gas outlet 122b.

  The medium U-turn path 120c is provided to communicate a plurality of medium flow paths (upstream medium flow path 123a and downstream medium flow path 123b) provided in the evaporator 12.

  FIG. 5B is a perspective view of the flow path of the medium inside the evaporator 12.

  The evaporator 12 has an upstream medium flow path (first medium flow path) 123a, an exhaust gas flow path 124, and a downstream medium flow path (second medium) from the upstream side to the downstream side in the flow direction of the cooling water. Each flow path) 123b is provided.

  Each of these flow paths is provided with a large number of fins so that a passing medium or the like passes through the flow paths evenly.

  FIG. 6 is a cross-sectional view of the evaporator 12. 6A is a cross-sectional view taken along the line AA in FIG. 5A, and FIG. 6B is a cross-sectional view taken along the line BB in FIG. 5A.

  The evaporator 12 has a hollow inside, and the cooling water is configured to flow through this hollow portion from the cooling water inlet 121a side to the cooling water outlet 121b side.

  In this hollow portion, an upstream medium flow path 123a, a downstream medium flow path 123b, and an exhaust gas flow path 124 are provided.

  FIG. 6A shows a cross-sectional view of the upstream medium flow path 123 a of the evaporator 12.

The medium is introduced into the evaporator 12 from the medium inlet 120a. At this time, the medium is divided into a plurality of upstream medium flow paths 123a. Heat exchange is performed with the cooling water flowing around the plurality of upstream medium flow paths 123a. Thereafter, the medium is once led out of the evaporator 12 via the medium U-turn path 120c and then introduced again into the downstream medium flow path 123b. Also in the downstream medium flow path 123b, heat exchange is performed with the cooling water flowing around.

  FIG. 6B shows a cross-sectional view of the cooling water flow path of the evaporator 12.

  Inside the evaporator 12, as described above, the upstream medium flow path 123a, the exhaust gas flow path 124, and the downstream medium flow path 123b are provided. And cooling water is comprised so that the circumference | surroundings of these each flow path may be orthogonal to these each flow path, and may flow from the cooling water inlet 121a to the cooling water outlet 121b.

  Next, the operation of the evaporator 12 configured as shown in FIGS. 5 and 6 will be described.

  The cooling water is introduced from the cooling water inlet 121a, flows through the inside of the evaporator 12, and then is led out from the cooling water outlet 121b.

  The medium is introduced from the medium inlet 120a and flows through the divided upstream medium flow path 123a. At this time, around the upstream medium flow path 123a, the cooling water flows substantially orthogonal to the medium flow direction. Here, the first heat exchange is performed between the medium and the cooling water.

  In the first heat exchange, cooling water (for example, 80 [° C.]) flowing from the engine 25 side and a medium liquefied by the condenser (for example, 50 [° C.]) exchange heat. As a result, the medium temperature slightly increases and the cooling water temperature slightly decreases.

  Thereafter, the medium is introduced into the downstream medium flow path 123b via the medium U-turn path 120c.

  On the other hand, the cooling water flows around the exhaust gas flow channel 124 after passing through the upstream medium flow channel 123a. Here, the second heat exchange is performed between the exhaust gas and the cooling water.

  In the second heat exchange, the cooling water (for example, 70 [° C.]) passing through the upstream medium flow path 123a and the introduced exhaust gas (for example, 400 [° C.]) perform heat exchange. As a result, the cooling water temperature slightly increases and the exhaust gas temperature slightly decreases.

  Thereafter, the exhaust gas is discharged from the exhaust gas outlet 122b to the exhaust pipe 34.

  On the other hand, after passing through the exhaust gas flow channel 124, the cooling water flows around the downstream medium flow channel 123b. Here, the third heat exchange is performed between the medium and the cooling water.

  In the third heat exchange, cooling water (eg, 90 [° C.]) whose temperature has increased due to heat exchange with exhaust gas and medium (eg, 70 [° C.) whose temperature has increased due to heat exchange in the upstream medium flow path 123a. ]) And heat exchange. As a result, the medium temperature further increases and the cooling water temperature slightly decreases.

  With this configuration, the evaporator 12 can appropriately increase the medium temperature by performing heat exchange through the cooling water without directly contacting the medium of the Rankine cycle system 10 and the exhaust gas. it can.

In particular, by configuring the evaporator 12 as shown in FIGS. 5 and 6, heat exchange in three stages of medium-cooling water, cooling water-exhaust gas, and cooling water-medium is performed. Thereby, the temperature of a medium can be raised gently and the efficiency of heat exchange can be improved.

  Furthermore, by making the inside of the evaporator 12 have such a structure, it is not always necessary to control the recovery / non-recovery of cooling water and exhaust gas by the control device 100 shown in FIG. If the internal structure of the evaporator 12 (flow rate and contact area of each flow path of the medium, cooling water, and exhaust gas) is appropriately designed, the temperature of the medium is kept within a predetermined range simply by circulating the medium, cooling water, and exhaust gas. It is also possible to control.

  FIG. 7 is an explanatory view showing still another example of the evaporator 12.

  The evaporator 12 shown in FIG. 6 has a medium U-turn path 120c outside. On the other hand, in the example shown in FIG. 7, a structure serving as a U-turn path is provided inside the evaporator 12.

  The evaporator 12 includes a medium inlet 120a, a medium outlet 120b, a cooling water inlet 121a, a cooling water outlet 121b, an exhaust gas inlet 122a, and an exhaust gas outlet 122b. These operations are almost the same as those in FIG.

  FIG. 7B is a perspective view of the medium flow path inside the evaporator 12.

  The inside of the evaporator 12 includes an upstream side cooling water flow path (first cooling water flow path) 126a communicating with the cooling water inlet 121a and a downstream side cooling water flow path (second cooling water flow path) communicating with the cooling water outlet 121b. 126b. These communicate with each other in a U-turn path 126c as will be described later with reference to FIG.

  The upstream cooling water flow path 126a includes an upstream medium flow path (first medium flow path) 123a and an upstream exhaust gas flow path (first exhaust gas flow path) 124a. Further, the downstream side cooling water passage 126b is provided with a downstream side exhaust passage (second exhaust passage) 124b and a downstream medium passage (second medium passage) 123b, respectively.

  Each of these flow paths is provided with a large number of fins so that the passing medium and the like pass through the flow paths evenly.

  FIG. 8 is a cross-sectional view of the evaporator 12 shown in FIG. 8A shows a cross-sectional view taken along the line AA in FIG. 7A, and FIG. 8B shows a cross-sectional view taken along the line BB in FIG. 7A.

  Similarly to the example shown in FIGS. 5 and 6 described above, the evaporator 12 has a cavity inside, and the cooling water flows through the cavity from the cooling water inlet 121a side to the cooling water outlet 121b side. It is configured. In this example, the cooling water is configured to change the flow direction in the U-turn path 126 c provided in the evaporator 12.

  FIG. 8A shows a cross-sectional view of the medium flow path (upstream medium flow path 123a and downstream medium flow path 123b) of the evaporator 12. FIG.

  The medium is introduced into the evaporator 12 from the medium inlet 120a. At this time, the medium is divided into a plurality of upstream medium flow paths 123a. Heat exchange is performed with the cooling water flowing around the plurality of upstream medium flow paths 123a. Thereafter, the flow of the medium is changed by the U-turn path 123c provided in the evaporator 12, and flows to the downstream medium flow path 123b.

The exhaust gas has the same structure. That is, the exhaust gas introduced into the upstream side exhaust gas flow path 124a flows through the U-turn path (124c) to the downstream side exhaust gas flow path 124b.

  FIG. 8B shows a cross-sectional view of the cooling water flow of the evaporator 12.

  The cooling water is introduced into the evaporator from the cooling water inlet 121a and first flows through the upstream side cooling water flow path 126a. Here, the cooling water passes around the upstream medium flow path 123a and the upstream exhaust gas flow path 124a. Thereafter, the flow direction is changed in the U-turn path 126c and flows to the downstream side cooling water flow path 126b. Here, the cooling water passes through the downstream side exhaust gas passage 124b and the downstream side cooling water passage 126b, and then is led out from the cooling water outlet 121b.

  By configuring as shown in FIGS. 7 and 8, the piping of the medium, the cooling water, and the exhaust gas can be made different from the evaporator 12 shown in FIGS. 5 and 6. Further, there is no need for an external U-turn path structure. Thereby, it becomes possible to design the layout of the medium path 11 and the cooling water path 21 suitable for the vehicle etc. to mount, and can improve space acquisition efficiency.

  As described above, in the Rankine cycle system 10 according to the first embodiment of the present invention, the exhaust heat of the engine 25 is converted to the heat source of the Rankine cycle system 10 by exchanging heat of the medium, the cooling water, and the exhaust gas in the evaporator 12. Can be used as

  In particular, in the present embodiment, heat exchange is performed not through direct heat exchange between the medium and the exhaust gas but through cooling water having a large specific heat capacity, so that thermal decomposition of the medium by high-temperature exhaust gas can be prevented. At the same time, heat exchange can be performed efficiently.

  Further, the evaporator 12 performs heat exchange with the medium, the cooling water, and the exhaust gas as one body. Therefore, the heat dissipation loss and the loss due to the piping are reduced without increasing the connection path, so that the energy efficiency is increased and the efficiency is high. Heat exchange can be performed.

  In addition, the evaporator 12 performs heat exchange with the medium, the cooling water, and the exhaust gas integrally, so that the evaporator 12 can be reduced in size, and the mountability is improved and the space efficiency is increased. And it can reduce in weight by size reduction and can improve a fuel consumption.

  Next, an exhaust heat recovery system according to a second embodiment of the present invention will be described.

  In the first embodiment described above, the medium of the Rankine cycle system 10 is heated using the exhaust gas discharged from the engine 25. On the other hand, in the second embodiment, it is common to use the exhaust gas for the reservoir for increasing the medium temperature, but the exhaust gas used for the EGR system is used for raising the medium temperature.

  FIG. 9 is an explanatory diagram of the exhaust heat recovery system according to the second embodiment of this invention.

  In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment, and the description is abbreviate | omitted.

  The exhaust pipe 34 is provided with an EGR valve 60. The EGR valve 60 is configured to have a variable opening degree according to a command from the control device 100.

  One of the EGR valves 60 communicates with the EGR passage 61. Depending on the open / close state of the EGR valve 60, the exhaust gas can be circulated to the evaporator 12 via the EGR passage 61.

  The exhaust gas guided to the evaporator 12 is guided to the intake pipe 33 via the EGR passage 62 and mixed with the intake air of the engine 25.

  By comprising in this way, the temperature of the medium of Rankine cycle system 10 can be raised using the waste heat by the waste gas used as EGR gas.

  Further, EGR gas is used for intake air of the engine 25. By configuring as shown in FIG. 9, the temperature of the EGR gas can be lowered by heat exchange without adding a new configuration such as an EGR cooler. Thereby, deterioration of the fuel efficiency of the engine 25 can be prevented.

  In the present embodiment, the evaporator 12 having the structure described with reference to FIGS. 2, 5, and 7 can be used.

  The control of the EGR valve 60 is performed by the control device 100. However, since the control of the EGR gas is closely related to the operating state of the engine 25, the engine 25 is controlled by the recovery / non-recovery control as shown in FIG. This may affect the fuel consumption and output of the car. In this case, it is preferable that the medium temperature is automatically controlled by the internal structure of the evaporator 12 using the evaporator 12 as shown in FIG.

It is explanatory drawing of the waste heat recovery system of the 1st Embodiment of this invention. It is a perspective view which shows the structure of the evaporator of this embodiment of the 1st Embodiment of this invention. It is explanatory drawing which shows the structure inside the evaporator of the 1st Embodiment of this invention. It is a flowchart which shows the process of the control apparatus of the 1st Embodiment of this invention. It is explanatory drawing which shows the other structure of the evaporator of the 1st Embodiment of this invention. It is sectional drawing of the other structure of the evaporator of the 1st Embodiment of this invention. It is explanatory drawing which shows other structure of the evaporator of the 1st Embodiment of this invention. It is sectional drawing of the further another structure of the evaporator of the 1st Embodiment of this invention. It is explanatory drawing of the waste heat recovery system of the 2nd Embodiment of this invention.

Explanation of symbols

10 Rankine cycle system 12 Evaporator 20 Engine cooling system 25 Engine 28 Distribution valve (cooling water recovery valve)
41 exhaust gas recovery valve 60 EGR valve 100 controller 120a medium inlet 120b medium outlet 120c medium U turn path 121a cooling water inlet 121b cooling water outlet 122a exhaust gas inlet 122b exhaust gas outlet 123a upstream medium flow path 123b downstream medium flow path 123c U turn Passage 124 exhaust gas passage 124a upstream exhaust gas passage 124b downstream exhaust gas passage 126a upstream cooling water passage 126b downstream cooling water passage 126c U-turn passage

Claims (7)

An internal combustion engine cooling system (20) for cooling the heat generated by the internal combustion engine (25) with cooling water;
A heat exchanger (12) for vaporizing the medium by heat exchange, an expander (13) for generating energy by the vaporized medium, a condenser (14) for condensing and liquefying the vaporized medium, A Rankine cycle system (10) comprising: a pump (15) for delivering the liquefied medium to the heat exchanger (12);
With
The heat exchanger (12) performs heat exchange between the cooling water and the exhaust gas of the internal combustion engine (25), and further performs heat exchange between the cooling water after the heat exchange and the medium. Waste heat recovery system. The exhaust heat recovery system according to claim 1,
The heat exchanger (12) is configured such that the flow path of the medium, the flow path of the cooling water, and the flow path of the exhaust gas are laminated in multiple layers.
An exhaust heat recovery system, wherein the cooling water channel is interposed between the medium channel and the exhaust gas channel. The exhaust heat recovery system according to claim 1,
The heat exchanger (12)
Heat exchange between the medium and the cooling water, heat exchange between the cooling water after the heat exchange and the exhaust gas, and heat exchange between the cooling water after the heat exchange and the medium. Waste heat recovery system. In the exhaust heat recovery system according to claim 3,
The heat exchanger (12)
A cooling water passage (121) through which the cooling water flows;
A first medium flow path (123a), an exhaust gas flow path (124), and a second medium flow path (123b) provided substantially orthogonally in the cooling water flow path;
With
The first medium flow path (123a) and the second medium flow path (123b) are connected by a U-turn path (120c),
The cooling water flows around the first medium flow path (123a), then flows around the exhaust gas flow path (124), and flows around the second medium flow path (123b).
The medium flows through the first medium flow path (123a), and then flows through the U-turn path (120c) to the second medium flow path (123b). Collection system. In the exhaust heat recovery system according to claim 3,
The heat exchanger (12)
A first cooling water channel (126a) and a second cooling water channel (126b) through which cooling water flows;
A first medium flow path (123a) and a first exhaust gas flow path (124a) provided substantially orthogonally in the first cooling water flow path (126a);
A second exhaust gas flow path (124b) and a second medium flow path (123b) provided substantially orthogonally in the second cooling water flow path (126b);
With
The first cooling water channel (126a) and the second cooling water channel (126b) are connected by a U-turn channel (126c),
The first medium flow path (123a) and the second medium flow path (123b) are connected by a U-turn path (123c),
The first exhaust gas passage (124a) and the second exhaust gas passage (124b) are connected by a U-turn passage (124c),
The cooling water flows around the first medium flow path (123a) and the first exhaust gas flow path (124a) in the first cooling water flow path, and then passes through the U-turn path (126c). After passing through the second exhaust gas flow path (124b) and the second medium flow path (123b), the medium flows through the first medium flow path (123a) and then the U-turn. Through the channel (123c) to the second medium channel (123b),
The exhaust gas flows through the first exhaust gas passage (124a), and then flows through the U-turn passage (124c) to the second exhaust gas passage (124b). Collection system. In the exhaust heat recovery system according to any one of claims 1 to 5,
The exhaust heat recovery system, wherein the exhaust gas after heat exchange in the heat exchanger (12) is circulated to an intake system of the internal combustion engine (25). In the exhaust heat recovery system according to any one of claims 1 to 5,
An exhaust gas recovery valve (41) for circulating exhaust gas through the heat exchanger (12);
A cooling water recovery valve (28) for circulating cooling water through the heat exchanger (12);
A control device (100) for controlling the exhaust gas recovery valve (41) and the cooling water recovery valve (28);
With
The control device (100)
When the internal combustion engine (25) is started, the exhaust gas recovery valve (41) and the cooling water recovery valve (28) are controlled to distribute the cooling water and the exhaust gas to the heat exchanger (12). Let
When the temperature of the cooling water flowing out from the heat exchanger (12) exceeds a predetermined temperature, the exhaust gas recovery valve (41) is controlled to stop the flow of the exhaust gas to the heat exchanger (12). ,
When the temperature of the medium flowing out from the heat exchanger (12) exceeds a predetermined temperature, or when the pressure of the medium flowing out from the heat exchanger (12) exceeds a predetermined pressure, the cooling water recovery valve (28) is controlled to stop the circulation of the cooling water to the heat exchanger (12).

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