Abstract:
A Rankine cycle system includes a boiler configured to apply waste heat to refrigerant circulating in an internal-combustion engine to vaporize the refrigerant; a gas-liquid separator configured to separate gas-liquid two-phase refrigerant, sent from the boiler, into gas phase fluid and liquid phase fluid; a superheater configured to superheat the gas phase fluid, sent from the gas-liquid separator, through heat exchange with exhaust gas of the internal-combustion engine; an expander configured to expand the gas phase fluid, passing through the superheater, to recover thermal energy, and a condenser configured to condense the gas phase fluid, passing through the expander, to return the gas phase fluid to liquid phase fluid. The gas-liquid separator is connected to the internal combustion engine via a refrigerant pipe. The internal combustion engine is fixed onto an engine mount of a vehicle. The gas-liquid separator is fixed to the internal combustion engine via a bracket.

Description:
TECHNICAL FIELD 
       [0001]    Embodiments of the present invention relate to a Rankine cycle system for vehicle, and more specifically, to a structure for mounting a Rankine cycle system on a vehicle. 
       BACKGROUND 
       [0002]    Patent Literature 1 discloses a technology regarding a Rankine cycle system mounted on a vehicle. In this Rankine cycle system, a liquid-phase fluid is boiled with waste heat of an engine into a gas-phase fluid. Work is taken out by allowing the gas-phase fluid to expand. The gas-phase fluid after the expansion is condensed and returned to the liquid-phase fluid. 
         [0003]    Following is a list of patent literatures which the applicant has noticed as related arts of embodiments the present invention. 
         [0004]    Patent Literature 1: JP 2015-94271 A 
         [0005]    Patent Literature 2: JP 2002-316530 A 
         [0006]    Patent Literature 3: JP 2011-189824 A 
       SUMMARY 
       [0007]    The Rankine cycle system has a structure in which its constituents are connected to one another with pipes and the like. In particular, to a gas-liquid separator, which is one of the constituents of the Rankine cycle system, pipes are provided which allow transfer of a refrigerant from/to system&#39;s constituents including an internal combustion engine. Therefore, in the case where the gas-liquid separator is fixed, for example, to the vehicle side, vibration of the internal combustion engine is caused to be transmitted to the vehicle via the pipe connecting the internal combustion engine to the gas-liquid separator. The aforementioned technology can be still improved in view of suppression of vibration of the vehicle since, in this technology, the Rankine cycle system is not sufficiently considered on a structure for mounting it on a moving object such as a vehicle. 
         [0008]    The present invention is devised in view of the aforementioned problem and an object thereof is to provide a Rankine cycle system for vehicle capable of suppressing vibration of an internal combustion engine from being directly transmitted from a gas-liquid separator to a vehicle. 
         [0009]    In order to achieve the aforementioned object, there is provided a Rankine cycle system for vehicle according to a first embodiment of the present invention, including: a boiler configured to apply waste heat to refrigerant circulating in an internal-combustion engine to vaporize the refrigerant; a gas-liquid separator configured to separate gas-liquid two-phase refrigerant, sent from the boiler, into gas phase fluid and liquid phase fluid; a superheater configured to superheat the gas phase fluid, sent from the gas-liquid separator, through heat exchange with exhaust gas of the internal-combustion engine; an expander configured to expand the gas phase fluid, passing through the superheater, to recover thermal energy; and a condenser configured to condense the gas phase fluid, passing through the expander, to return the gas phase fluid to liquid phase fluid, wherein the gas-liquid separator is connected to the internal combustion engine via a refrigerant pipe, the internal combustion engine is fixed onto an engine mount of a vehicle, and the gas-liquid separator is fixed to the internal combustion engine via a bracket. 
         [0010]    According to a second embodiment of the present invention, in the first embodiment, the gas-liquid separator is connected to the superheater via a refrigerant pipe, and the superheater is fixed to the internal combustion engine. 
         [0011]    According to a third embodiment of the present invention, in the second embodiment, the superheater is connected to the expander via a refrigerant pipe, and the expander is fixed to the internal combustion engine. 
         [0012]    According to a fourth embodiment of the present invention, in the second embodiment, the superheater is integrally configured with an exhaust gas manifold fixed to the internal combustion engine. 
         [0013]    According to the first embodiment, the internal combustion engine is fixed to the engine mount, and the gas-liquid separator is fixed to the internal combustion engine via the bracket. Vibration of the internal combustion engine is transmitted to the gas-liquid separator via the refrigerant pipe. Therefore, according to this embodiment, vibration of the internal combustion engine can be prevented from being directly transmitted from the gas-liquid separator to the vehicle since the gas-liquid separator is fixed to the internal combustion engine. 
         [0014]    According to the second embodiment, the superheater connected to the gas-liquid separator with the refrigerant pipe is fixed to the internal combustion engine. Therefore, according to this embodiment, vibration transmitted to the superheater via the refrigerant pipe can be prevented from being directly transmitted to the vehicle. 
         [0015]    According to the third embodiment, the expander connected to the superheater with the refrigerant pipe is fixed to the internal combustion engine. Therefore, according to this embodiment, vibration transmitted to the expander via the refrigerant pipe can be prevented from being directly transmitted to the vehicle. 
         [0016]    According to the fourth embodiment, the superheater is integrally configured with the exhaust gas manifold fixed to the internal combustion engine. Therefore, according to this embodiment, vibration of the internal combustion engine can be prevented from being directly transmitted from the superheater to the vehicle. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is a diagram illustrating a configuration of a Rankine cycle system of a first embodiment of the present invention; 
           [0018]      FIGS. 2A and 2B  are schematic diagrams for explaining a structure for fixing a gas-liquid separator; 
           [0019]      FIG. 3  is a diagram for explaining a structure for mounting the Rankine cycle system having the gas-liquid separator fixed to an engine on a vehicle; and 
           [0020]      FIG. 4  is a diagram for explaining a structure for mounting the Rankine cycle system having the gas-liquid separator fixed to the vehicle on the vehicle. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0021]    Hereafter, embodiments of the present invention are described with reference to the drawings. Common elements across the drawings are given the same reference signs and duplicated description of those is omitted. In the following embodiments, when numerical values are mentioned such as the quantity of each element, the number thereof, the amount thereof and the range thereof, any of the mentioned numerical values does not limit the invention except that it is particularly explicitly presented or it is definitely specified so in principle. Any of the following structures described in the embodiments is not always necessary for the invention except that it is particularly explicitly presented or it is definitely specified so in principle. 
       First Embodiment 
       [0022]    1. Configuration of Rankine Cycle System 
         [0023]      FIG. 1  is a diagram illustrating a configuration of a Rankine cycle system  100  of a first embodiment. The Rankine cycle system  100  of the first embodiment is a Rankine cycle system for vehicle which includes an internal combustion engine (engine)  10  and is mounted on a vehicle. The engine  10  is not limited in its type and structure except that the engine  10  has, at its cylinder blocks and cylinder heads, a refrigerant flow channel  12  which a refrigerant circulated in the engine  10  flows through. The refrigerant flow channel  12  includes a water jacket surrounding the cylinders. The engine  10  is cooled through heat exchange with the refrigerant flowing through the refrigerant flow channel  12 . In the present embodiment, water is used as the refrigerant. 
         [0024]    The refrigerant flowing through the refrigerant flow channel  12  is boiled with waste heat of the engine  10  and a part thereof is vaporized. The engine  10  is thus cooled. Namely, the refrigerant flow channel  12  serves as a boiler which boils the liquid-phase refrigerant flowing therethrough with the heat of the engine  10 . The configuration of the refrigerant flow channel  12  is not specially limited as long as the refrigerant can pass through inside the engine  10 . The refrigerant, which passes through the refrigerant flow channel  12 , is not limited to water but may be a liquid-phase fluid at ambient temperature that is boiled into a gas-phase fluid with heat of the engine  10 . 
         [0025]    The refrigerant flow channel  12  of the engine  10  is connected to a gas-liquid separator  16  via a refrigerant pipe  14 . After the refrigerant is boiled with heat of the engine  10 , a liquid-phase fluid and a gas-phase fluid are ejected from the refrigerant flow channel  12 . The gas-liquid separator  16  separates the refrigerant in gas-liquid two phases which flows into the gas-liquid separator  16 , into the liquid-phase fluid and the gas-phase fluid. The gas-liquid separator  16  is connected to a first water pump  20  via a refrigerant pipe  18 . The liquid-phase fluid separated by the gas-liquid separator  16  flows into the first water pump  20  through the refrigerant pipe  18  and is sent to the refrigerant flow channel  12  by the first water pump  20 . 
         [0026]    The Rankine cycle system  100  includes an exhaust gas heat recovery unit  13 . The refrigerant flow channel  12  is also connected to the exhaust gas heat recovery unit  13  via a refrigerant pipe  11 . Into the exhaust gas heat recovery unit  13 , the liquid-phase fluid is introduced from the refrigerant flow channel  12 . The introduced liquid-phase fluid is superheated through heat exchange with exhaust gas flowing through an exhaust gas passage  22  to be boiled, and a part thereof is vaporized. The vaporized gas-phase fluid is introduced into the gas-liquid separator  16  via a refrigerant pipe  15 . 
         [0027]    The gas-liquid separator  16  is connected to a superheater  30  via a refrigerant pipe  28 . The superheater  30  is provided upstream of the exhaust gas heat recovery unit  13  on the exhaust gas passage  22  of the engine  10 . More in detail, the superheater  30  circumferentially covers an exhaust gas manifold  26  and is integrated with the exhaust gas manifold  26 . A space surrounded by the inner wall surface of the superheater  30  and the outer wall surface of the exhaust gas manifold  26  is a flow channel which the gas-phase fluid sent from the gas-liquid separator  16  flows through. In the gas-liquid separator  16 , the gas-phase fluid is saturated vapor since the gas-phase fluid is present along with the liquid-phase fluid. The gas-phase fluid entering the superheater  30  becomes superheated vapor after absorbing exhaust gas heat transmitted through the wall surface of the exhaust gas manifold  26 . 
         [0028]    The superheater  30  is connected to a turbine  34  which is an expander via a refrigerant pipe  32 . In the turbine  34 , thermal energy is recovered by allowing the gas-phase fluid (superheated vapor) sent from the superheater  30  to expand. A not-shown supersonic nozzle is provided at a connection between the refrigerant pipe  32  and the turbine  34 . The gas-phase fluid is ejected into the turbine  34  from the supersonic nozzle to rotate the turbine  34 . The rotation of the turbine  34  is transmitted to an output shaft of the engine  10  via a not-shown reduction gear. Namely, the thermal energy recovered through the turbine  34  assists the engine  10 . The turbine  34  may drive a generator instead to store the generated electricity in a power storage. 
         [0029]    The gas-phase fluid expanded in the turbine  34  is sent to a condenser  40  via a refrigerant pipe  36 . A liquid-phase fluid, which can be generated through condensation of the gas-phase fluid in the middle of the refrigerant pipe  36 , is temporarily stored in a condensed water tank  38  provided in the middle of the refrigerant pipe  36 . The condensed water tank  38  is connected to a catch tank  44  mentioned later via a refrigerant pipe  39 . The gas-phase fluid sent to the condenser  40  is cooled and condensed by the condenser  40  to be returned to a liquid-phase fluid. The liquid-phase fluid generated through the condensation of the gas-phase fluid is sent to the catch tank  44  from the condenser  40  via a refrigerant pipe  42 , and is temporarily stored in the catch tank  44 . The catch tank  44  is connected to the first water pump  20  via a refrigerant pipe  46 . A second water pump  48  is provided on the refrigerant pipe  46 . The second water pump  48  sends the liquid-phase fluid stored in the catch tank  44  to the first water pump  20 . A not-shown check valve is provided between the second water pump  48  and the gas-liquid separator  16  to prevent the liquid-phase fluid from flowing back from the gas-liquid separator  16  side to the catch tank  44  side. The refrigerant pipe  46  may connect the catch tank  44  to the middle of refrigerant pipe  18  instead. In this configuration, drive of the second water pump  48  sends the liquid-phase fluid stored in the catch tank  44  to the gas-liquid separator  16  and the engine  10 . The lower end of the catch tank  44  is connected to the lower end of a refrigerant tank  52  via a refrigerant pipe  50 . To the upper end of the refrigerant tank  52 , a refrigerant pipe  54  is connected whose end is connected to the upper end of the condenser  40 . 
         [0030]    The Rankine cycle system  100  includes an electronic control unit (ECU)  70  as a controller. The ECU  70  at least includes an I/O interface, a memory and a processor (CPU). The I/O interface is provided for taking in sensor signals from sensors attached to the Rankine cycle system  100  or the engine  10  having the same mounted, and for outputting operation signals to actuators included in the Rankine cycle system  100 . The memory stores control programs, maps and the like. The CPU reads and executes the control program or the like from the memory, and generates the operation signals for the actuators on the basis of the taken-in sensor signals. 
         [0031]    2. Structure for Mounting Rankine Cycle System on Vehicle 
         [0032]    The Rankine cycle system  100  is mounted inside an engine compartment of a vehicle for accommodating the engine  10 . The engine  10  is fixed onto an engine mount in the engine compartment. The engine mount absorbs the vibration of the engine  10 , and can suppress the vibration from being transmitted from the engine  10  to the vehicle side. 
         [0033]    There are various restrictions in arranging the constituents of the Rankine cycle system  100  due to the limited space in the engine compartment for mounting them. Meanwhile, the gas-liquid separator  16 , which is one of the constituents of the Rankine cycle system  100 , needs a relatively large volume for stably supplying the vapor. Only in view of the space for mounting the gas-liquid separator  16 , it should be disposed at a place apart from the engine  10 . As a result, it is also supposed that the gas-liquid separator  16  be fixed onto the vehicle body side. 
         [0034]    Vibration of the engine  10  is caused to be transmitted to the vehicle via the refrigerant pipe  14  when the gas-liquid separator  16  is directly fixed to a member constituting the vehicle framework since the gas-liquid separator  16  is connected to the refrigerant flow channel  12  of the engine  10  via the refrigerant pipe  14  as mentioned above. In particular, there is typically used a metal-made, large-diameter pipe to pass a gas-phase fluid (vapor) as well as a liquid-phase fluid, such as the refrigerant pipe  14 , for its heat resistance and pressure resistance. Use of such a pipe increases vibration transmitted from the engine  10  to the gas-liquid separator  16 , which results in large vibration to be transmitted to the vehicle. 
         [0035]    Therefore, the inventors in the present application have been intensively studying structures for mounting the gas-liquid separator  16  on the vehicle in order to suppress vibration transmitted, not via the engine mount, from the engine  10  to the vehicle. The inventors in the present application have eventually found the structure for mounting the gas-liquid separator  16  on the vehicle, which structure will be described below. 
         [0036]    2-1. Structure for Fixing Gas-Liquid Separator 
         [0037]      FIGS. 2A and 2B  are schematic diagrams for explaining a structure for fixing the gas-liquid separator.  FIG. 2A  is a diagram of the Rankine cycle system in plan view above the vehicle.  FIGS. 2B  is a diagram of the Rankine cycle system mounted on the vehicle in elevation view beside the vehicle. In  FIGS. 2A and 2B , elements other than the main constituents of the Rankine cycle system  100  are omitted. As illustrated in  FIGS. 2A and 2B , the Rankine cycle system  100  is mounted inside an engine compartment  1  of the vehicle. The engine  10  is mounted on the engine mount (not shown) provided in the engine compartment  1 . 
         [0038]    Reference sign S 1  in  FIG. 2A  denotes a plane which includes center axes L 1  of cylinders  104  and is parallel to the direction of the cylinders  104  lining up which are provided in series along the longitudinal direction of a cylinder block  102 . Reference sign S 2  in  FIG. 2B  denotes a plane on which a cylinder head  101  meets the cylinder block  102 . In the following description, “exhaust side” designates the exhaust side, of the engine  10  relative to the plane S 1 , on which the exhaust gas passage  22  is provided, and “air intake side” designates the air intake side of the engine  10  relative to the plane S 1 . 
         [0039]    In the fixing structure illustrated in  FIG. 2 , a transmitter  103  is fixed onto a lateral face of the cylinder block  102 . The gas-liquid separator  16  is disposed in a space which is on the exhaust side (that is, the side of the exhaust gas passage  22  of the engine  10 ) above the transmitter  103 , and is fixed to the engine  10  via brackets  2   a  and  2   b.  More in detail, one end of the bracket  2   a  is fixed to the upper part of the gas-liquid separator  16  and the other end thereof is fixed onto the upper face of the cylinder head  101  of the engine  10 . Moreover, one end of the bracket  2   b  is fixed to the lower part of the gas-liquid separator  16  and the other end thereof is fixed onto a lateral face of the cylinder block  102  of the engine  10 . The brackets  2   a  and  2   b  are formed by processing metal plates, and each of them has a shape which can secure strength needed for fixing the gas-liquid separator  16 . With bolts, the brackets  2   a  and  2   b  are fixed to the engine  10  and the brackets  2   a  and  2   b  are fixed to the gas-liquid separator  16 . 
         [0040]    According to the aforementioned structure for fixing the gas-liquid separator  16 , the gas-liquid separator  16  is fixed to the engine  10 . This can prevent direct transmission of the vibration to the vehicle, the vibration having been transmitted to the gas-liquid separator  16  via the refrigerant pipe  14 . Hence, vibration of the vehicle can be suppressed. Moreover, the gas-liquid separator  16  can be effectively suppressed from shaking since the gas-liquid separator  16  is fixed at its upper part and lower part with the brackets  2   a  and  2   b.    
         [0041]    A method of fixing the brackets, the number thereof and the shape thereof are not limited as long as the brackets  2   a  and  2   b  can be fixed to the engine  10 . The material of the brackets  2   a  and  2   b  is not limited to metal. The material preferably has high strength since they fix the gas-liquid separator  16 , which is typically heavy. 
         [0042]    2-2. Structure for Fixing Superheater 
         [0043]    As mentioned above, transmission of the vibration to the vehicle can be suppressed since the gas-liquid separator  16  is fixed to the engine  10  in the Rankine cycle system  100  of the first embodiment. Now, as illustrated in  FIG. 2 , refrigerant pipes other than the refrigerant pipe  14  are also connected to the gas-liquid separator  16 . For example, the refrigerant pipe  28  connects the gas-liquid separator  16  and the superheater  30  together. Via the refrigerant pipe  28 , the vibration transmitted to the gas-liquid separator  16  is transmitted also to the superheater  30 . Depending on a structure for fixing the superheater  30 , vibration of the vehicle can be further suppressed. 
         [0044]    With this point being in mind, the superheater  30  is integrated with the exhaust gas manifold  26  in the Rankine cycle system  100  of the first embodiment. The exhaust gas manifold  26  is fixed to the engine  10 . The vibration, of the gas-liquid separator  16 , transmitted to the superheater  30  via the refrigerant pipe  28  is not directly transmitted to the vehicle. According to the aforementioned structure for fixing the superheater  30 , vibration of the vehicle can be further suppressed. 
         [0045]    The shape or the structure of the superheater  30  is not limited as long as it can be fixed to the engine  10 . Namely, the superheater  30  may be integrated, for example, with another portion which can absorb the exhaust gas heat, such as a catalyst, not limited to the structure of being integrated with the exhaust gas manifold  26 . Otherwise, it may also be fixed to the engine  10  at any place where it can absorb the exhaust gas heat. 
         [0046]    2-3. Structure for Fixing Turbine 
         [0047]    As mentioned above, transmission of the vibration to the vehicle can be suppressed since the gas-liquid separator  16  and the superheater  30  are fixed to the engine  10  in the Rankine cycle system  100  of the first embodiment. Now, as illustrated in  FIG. 2 , the superheater  30  is connected to the turbine  34  via the refrigerant pipe  32 . Via the refrigerant pipe  32 , the vibration transmitted from the gas-liquid separator  16  to the superheater  30  is transmitted to the turbine  34 . Depending on a structure for fixing the turbine  34 , vibration of the vehicle can be further suppressed. 
         [0048]    With this point being in mind, the turbine  34  is fixed to the engine  10  in the Rankine cycle system  100  of the first embodiment. According to such a structure, the vibration transmitted to the turbine  34  from the superheater  30  through the refrigerant pipe  32  is not directly transmitted to the vehicle. According to the aforementioned structure for fixing the turbine  34 , vibration of the vehicle can be further suppressed. The structure for fixing the turbine  34  is not limited as long as it can be fixed to the engine  10 . 
         [0049]    3. Example of Structure for Mounting Rankine Cycle System 100 on Vehicle 
         [0050]    Next, the structure for mounting the Rankine cycle system  100  of the first embodiment on the vehicle is described along with a comparative example.  FIG. 3  is a diagram for explaining a structure for mounting a Rankine cycle system in which a gas-liquid separator is fixed to an engine on a vehicle.  FIG. 4  is a diagram for explaining a structure for mounting a Rankine cycle system in which a gas-liquid separator is fixed to a vehicle, on the vehicle.  FIG. 3  corresponds to the structure for mounting the Rankine cycle system  100  of the first embodiment of the present invention on the vehicle.  FIG. 4  corresponds to a comparative example of the Rankine cycle system  100  of the first embodiment of the present invention. Each of  FIG. 3  and  FIG. 4  schematically illustrates an arrangement of the constituents of the Rankine cycle system in side view beside the vehicle. Moreover, in  FIG. 3  and  FIG. 4 , elements other than the main constituents of the Rankine cycle system are omitted. 
         [0051]    3-1. Discussion of Comparative Example 
         [0052]    In the comparative example illustrated in  FIG. 4 , the gas-liquid separator  16  is fixed to the vehicle while the superheater  30  and the turbine  34  are fixed to the engine  10 . In such a structure, the vibration of the engine  10 , which vibration is further transmitted to the gas-liquid separator  16  via the refrigerant pipes  14 ,  28  and  18 , is caused to be transmitted, not via the engine mount, to the vehicle, which results in larger vibration of the vehicle. 
         [0053]    3-2. Discussion of Vehicle Mounting Structure of First Embodiment 
         [0054]    On the contrary, in the vehicle mounting structure illustrated in  FIG. 3 , the gas-liquid separator  16  is fixed to the engine  10 . In such a structure, there is no path through which the vibration is directly transmitted from the gas-liquid separator  16  to the vehicle body. The Rankine cycle system of the embodiment can reduce paths through which the vibration is transmitted between the engine  10  and the vehicle more than the Rankine cycle system of the comparative example. Therefore, vibration of the vehicle can be effectively suppressed.