Abstract:
A heat pump device for a vehicle capable of effectively utilizing the heat of structural members. This heat pump device for a vehicle comprises: an electric compressor for compressing and discharging refrigerant and a high-temperature water-refrigerant heat exchanger for conducting heat exchange between the high-temperature, high-pressure refrigerant discharged by the electric compressor and a first cooling liquid which is antifreeze, the high-temperature water-refrigerant heat exchanger surrounding and being in contact with the electric compressor so as to be capable of heat exchange with the electric compressor.

Description:
TECHNICAL FIELD 
     The present invention relates to an in-vehicle heat pump apparatus. 
     BACKGROUND ART 
     In-vehicle heat pump apparatuses provided with a heat pump and configured to exchange heat between refrigerant and coolant have been known. Non-Patent Literature (hereinafter, referred to as “NPL”) 1 discloses a temperature adjustment system for a vehicle provided with an in-vehicle heat pump air conditioner (HPAC) and configured to perform cooling and heating of the vehicle interior using a coolant extracted by the in-vehicle heat pump apparatus. This in-vehicle heat pump apparatus includes: a compressor that compresses refrigerant; a condenser that performs heat radiation from the refrigerant to the coolant; a cooler that cools the coolant using the refrigerant; a condenser pump that sends out the coolant to the condenser; and a cooler pump that sends out the coolant to the cooler. 
     Moreover, as a related art of the invention of the subject application, Patent Literature (hereinafter, referred to as “PTL”) 1 discloses a refrigerating device in which a tube of a refrigerant water heat exchanger is placed around a compressor with a space between the tube and compressor (see, FIGS. 22 and 24 of PTL 1). 
     CITATION LIST 
     Patent Literature 
     PTL 1 
     
         
         Japanese Patent No. 3477868
 
Non-Patent Literature
 
NPL 1
 
         Kowsky et al., “Unitary HPAC System,” SAE International J. Passeng. Cars—Mech. Syst., 2012, doi: 10.4271/2012-01-1050. 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In the in-vehicle heat pump apparatus according to the related art disclosed in NPL 1, however, component elements including the electric compressor, condenser, cooler, condenser pump, and cooler pump are placed without being housed in a casing. For this reason, the heat released from the component elements simply spreads in the in-vehicle heat pump apparatus of the related art. 
     Furthermore, in the in-vehicle heat pump apparatus of NPL 1, the component elements are placed while being spaced apart from each other. For this reason, the pipes for connecting the component elements cannot be reduced in length in the case of the in-vehicle heat pump apparatus of the related art. Accordingly, a large amount of heat is released from the pipes, and the effective utilization of heat has been difficult in the case of the in-vehicle heat pump apparatus of the related art. 
     Moreover, in the in-vehicle heat pump apparatus of NPL 1, the component elements are disposed while being spaced apart from each other. For this reason, the component elements are thermally distant from each other, and the heat released from each of the component elements such as the heat released from the electric compressor is simply wasted, and the effective utilization of heat has been difficult. 
     Moreover, in the refrigerating device of PTL 1, the tube of the water refrigerant heat exchanger is disposed while being spaced from the compressor, so that the heat from the compressor is barely transmitted to the water refrigerant heat exchanger. Moreover, in the refrigerant heat exchanger of PTL 1, the coolant flows through the center of the tube while the refrigerant flows through the outside of the tube. For this reason, heat radiation for the coolant of the water refrigerant heat exchanger from the compressor is barely performed. 
     An object of the present invention is to provide an in-vehicle heat pump apparatus that enables the effective utilization of heat of the component elements. 
     Solution to Problem 
     An in-vehicle heat pump apparatus according to the disclosure includes: an electric compressor that compresses and discharges refrigerant; a high-temperature-side water refrigerant heat exchanger that performs heat exchange between a high-temperature and high-pressure refrigerant discharged from the electric compressor and a first coolant that is an anti-freeze liquid, in which the high-temperature-side water refrigerant heat exchanger surrounds the electric compressor and is in contact with the electric compressor in a heat exchangeable manner. 
     Advantageous Effects of Invention 
     According to the present disclosure, a high-temperature-side water refrigerant heat exchanger surrounds an electric compressor and is in contact with the electric compressor in a heat-exchangeable manner, thereby producing the effect of enabling the effective utilization of heat of the component elements. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view illustrating an in-vehicle heat pump apparatus according to Embodiment 1 of the present invention; 
         FIG. 2  is a partially broken view illustrating the in-vehicle heat pump apparatus according to Embodiment 1; 
         FIG. 3  is a block diagram illustrating a control configuration of the in-vehicle heat pump apparatus according to Embodiment 1; 
         FIG. 4  is a diagram for describing the flow of refrigerant and coolant of the in-vehicle heat pump apparatus according to Embodiment 1; 
         FIG. 5  is a diagram for describing a vehicle temperature adjustment system using a vehicle heat pump apparatus; 
         FIG. 6  is another diagram for describing the vehicle temperature adjustment system using the vehicle heat pump apparatus; 
         FIG. 7  is a partially broken perspective view illustrating a configuration of a casing side of a compressor of Embodiment 1; 
         FIG. 8  is another partially broken perspective view illustrating the configuration of the casing side of the compressor of Embodiment 1; 
         FIG. 9  is a cross-sectional view illustrating the configuration of the casing side of the compressor of Embodiment 1; 
         FIG. 10  is a cross-sectional view taken along the line D-D of  FIG. 9 ; 
         FIG. 11  is a perspective view illustrating a variation of how an accumulator is placed; and 
         FIG. 12  is a perspective view illustrating an in-vehicle heat pump apparatus according to Embodiment 2 of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, a description will be given of an embodiment of the present invention with reference to the accompanying drawings. Note that, basically, the same elements are assigned the same reference numerals throughout the entire drawings, and a redundant description will be omitted. 
     Embodiment 1 
     Configuration of In-Vehicle Heat Pump Apparatus 
     Each component in Embodiment 1 of the present invention will be described with reference to  FIGS. 1 and 2 .  FIGS. 1 and 2  are diagrams illustrating a configuration of an in-vehicle heat pump apparatus according to Embodiment 1. 
     In-vehicle heat pump apparatus  1  is configured to be mounted on a vehicle and includes: low-temperature-side water refrigerant heat exchanger  110 ; high-temperature-side water refrigerant heat exchanger  111 ; and electric compressor  112  that compresses refrigerant and discharges the refrigerant. The term “vehicle” herein refers to an electric vehicle, for example. The term “electric vehicle” refers to a vehicle that runs on a storage battery mounted on the vehicle, such as an EV (Electric Vehicle), PHEV (Plug-in Hybrid Electric Vehicle), or HEV (Hybrid Electric Vehicle). 
     In-vehicle heat pump apparatus  1  includes a heat pump therein and exchanges heat between the refrigerant of the heat pump and the high-temperature-side coolant (corresponding to the first coolant) as well as the low-temperature-side coolant (corresponding to the second coolant). The low-temperature-side coolant and high-temperature-side coolant are introduced from the outside of in-vehicle heat pump apparatus  1 . 
     The refrigerant to be employed herein is one that has a high working pressure and that can improve the efficiency of heat pump cycle even under an extremely low temperature environment required for electric vehicles, such as carbon dioxide (CO 2 ). 
     The coolant to be employed herein includes a liquid such as an ethylene glycol aqueous solution. As long as an antifreeze solution is used, any solution is acceptable as the coolant. Accordingly, a propylene glycol aqueous solution other than an ethylene glycol aqueous solution can be employed as the coolant. 
     The high-temperature-side coolant is introduced from the outside of in-vehicle heat pump apparatus  1  via high-temperature-side introduction pipe  104  (arrow B of  FIG. 1 ). The introduced coolant is heated by high-temperature-side water refrigerant heat exchanger  111  and discharged from high-temperature-side discharge pipe  105  (arrow B of  FIG. 1 ). The coolant is transported by the driving force of an electric motor included in high-temperature-side water pump  101 . 
     High-temperature-side water refrigerant heat exchanger  111  includes a passage through which the refrigerant flows and a passage through which the high-temperature-side coolant flows and is configured to move heat between these passages. 
     The low-temperature-side coolant is introduced from the outside of in-vehicle heat pump apparatus  1  via low-temperature-side introduction pipe  106  (arrow A in  FIG. 1 ). The introduced coolant is cooled by low-temperature-side water refrigerant heat exchanger  110  and discharged from low-temperature-side discharge pipe  107  (arrow A in  FIG. 1 ). The coolant is transported by the driving force of the electric motor included in low-temperature-side water pump  102 . 
     Low-temperature-side water refrigerant heat exchanger  110  includes a passage through which the refrigerant flows and a passage through which the low-temperature-side coolant flows, and is configured to transfer the heat between these passages. 
     Electric compressor  112  includes electric motor  112   a , compression mechanism  112   b , and compressor casing (corresponding to first casing)  109 , for example. Compression mechanism  112   b  is a mechanism configured to compress refrigerant by the driving force generated by electric motor  112   a . A scroll type compression mechanism can be used for compression mechanism  112   b , for example. Electric motor  112   a  is electrically driven by inverter  113 . Inverter  113  includes semiconductors for electric power and generates and supplies three-phase AC power to electric motor  112   a.    
     Compressor casing  109  is used to encapsulate the refrigerant that is processed in electric compressor  112 , so as to prevent the refrigerant from leaking to the outside of compressor casing  109 . The refrigerant passing through electric compressor  112  flows through the inner side of compressor casing  109 . 
     Electric compressor  112  constitutes a high-pressure shell type compressor. The term “high-pressure shell type compressor” refers to a compressor type having a structure with which the high-pressure refrigerant compressed by compression mechanism  112   b  flows between electric motor  112   a  and compressor casing  109  and which allows compressor casing  109  to bear the high-pressure refrigerant. In a low-pressure shell type compressor, the low-temperature and low-pressure refrigerant before compression flows around the electric motor and is thus heated. As a result, the refrigerant introduced into the compression mechanism expands and is diluted. In this case, the density of refrigerant introduced into compression mechanism  112   b  becomes low, so that the air conditioning performance degrades. Meanwhile, adopting a high-pressure cell type compressor makes it possible to avoid a situation where the refrigerant before compression is heated without discretion and thus to improve the air conditioning performance. 
     In-vehicle heat pump apparatus  1  includes accumulator  108  on the upstream of an entry for the refrigerant of electric compressor  112 . Accumulator  108  serves a role of supplying only the refrigerant gas to electric compressor  112  by separating the refrigerant into the gas and liquid. Accumulator  108  serves this role for the purpose of preventing electric compressor  112  from being broken. 
     In addition, in-vehicle heat pump apparatus  1  includes expansion valve  114  on the upstream of an entry for the refrigerant of low-temperature-side water refrigerant heat exchanger  110 . Expansion valve  114  expands the high-pressure refrigerant on the downstream of the high-temperature-side water refrigerant heat exchanger without causing any change in the amount of heat and decreases the temperature and pressure of the high-pressure refrigerant. The low-temperature and low-pressure refrigerant that has passed through expansion valve  114  is sent to low-temperature-side water refrigerant heat exchanger  110 . 
     In-vehicle heat pump apparatus  1  includes power feeding section  103  used for receiving the electric supplied from the outside of in-vehicle heat pump apparatus  1 . Power feeding section  103  is provided on the outer wall of compressor casing  109 . The electrical energy supplied to power feeding section  103  is used for driving the electric motors respectively provided to electric compressor  112 , high-temperature-side water pump  101 , and low-temperature-side water pump  102 . 
     &lt;Control Configuration of In-Vehicle Heat Pump Apparatus&gt; 
       FIG. 3  is a block diagram illustrating a control configuration of the in-vehicle heat pump apparatus according to Embodiment 1. 
     In-vehicle heat pump apparatus  1  further includes control section  121 , and temperature sensor  122 . 
     Temperature sensor  122  detects a temperature related to a discharge temperature of the refrigerant from electric compressor  112  (see  FIG. 4 ) and outputs the detection signal to control section  121 . 
     Control section  121  controls the rotation of electric motor  112   a  of electric compressor  112 . Control section  121  controls electric motor  112   a  so as to reduce the rotation speed of electric motor  112   a , when the discharge temperature of the refrigerant exceeds a predetermined temperature based on the output of temperature sensor  122 . Control section  121  is installed in the circuit casing fixed to the outer wall of compressor casing  109 , for example. 
     &lt;Operation of In-Vehicle Heat Pump Apparatus&gt; 
     Next, a description will be given of the flow of refrigerant and coolant of in-vehicle heat pump apparatus  1  with reference to  FIG. 4 . 
     To begin with, the flow of refrigerant will be described. Arrow C in  FIG. 4  illustrates the direction in which the refrigerant flows. The refrigerant flows in the order of electric compressor  112 , high-temperature-side water refrigerant heat exchanger  111 , expansion valve  114 , and low-temperature-side water refrigerant heat exchanger  110 . This flow of the refrigerant forms a heat pump cycle. 
     The high-temperature and high-pressure refrigerant compressed by electric compressor  112  and discharged therefrom turns into a liquid after release of heat in high-temperature-side water refrigerant heat exchanger  111 . The refrigerant that has turned into a liquid drastically expands at expansion valve  114  and becomes a low-temperature and low-pressure refrigerant. This low-temperature and low-pressure refrigerant absorbs heat and evaporates in low-temperature-side water refrigerant heat exchanger  110 . The evaporated refrigerant passes through accumulator  108  and is compressed again in electric compressor  112 . 
     Next, the flow of coolant will be described. The coolant introduced from the outside of compressor casing  109  via high-temperature-side introduction pipe  104  is heated by heat exchange with the high temperature refrigerant in high-temperature-side water refrigerant heat exchanger  111 . The heated coolant is discharged from high-temperature-side discharge pipe  105 . 
     The coolant introduced from the outside of in-vehicle heat pump apparatus  1  via low-temperature-side introduction pipe  106  is cooled by heat exchange with the low-temperature refrigerant in low-temperature-side water refrigerant heat exchanger  110  and discharged from low-temperature-side discharge pipe  107 . 
     As described above, in-vehicle heat pump apparatus  1  of Embodiment 1 achieves a heat pump cycle by circulating the refrigerant within the apparatus. Furthermore, high-temperature-side water refrigerant heat exchanger  111  and low-temperature-side water refrigerant heat exchanger  110  exchanges heat between the liquid and refrigerant (coolant) rather than air. With this configuration, in-vehicle heat pump apparatus  1  can absorb heat from a place distant from in-vehicle heat pump apparatus  1  via the coolant and release heat to a place distant from in-vehicle heat pump apparatus  1 . 
     &lt;Vehicle Temperature Adjustment System&gt; 
     Next, a description will be given of a vehicle temperature adjustment system using in-vehicle heat pump apparatus  1  with reference to  FIGS. 5 and 6 .  FIG. 5  is an explanatory diagram of the vehicle temperature adjustment system during the heating operation, and  FIG. 6  is an explanatory diagram of the vehicle temperature adjustment system during the cooling operation. 
     The heated coolant discharged from high-temperature-side discharge pipe  105  and the cooled coolant discharged from low-temperature-side discharge pipe  107  are introduced into in-vehicle air conditioning apparatus  2  and are used for cooling or heating. In-vehicle air conditioning apparatus  2  is an apparatus that is placed on the vehicle interior side of fire wall  7  and that performs air conditioning of the vehicle interior. In-vehicle heat pump apparatus  1  is placed on the outer side of the vehicle interior of fire wall  7 . 
     In-vehicle air conditioning apparatus  2  includes cooling air refrigerant heat exchanger  200 , heating air refrigerant heat exchanger  201 , blower fan  202 , and switching door  203 . 
     Cooling air refrigerant heat exchanger  200  exchanges heat between the air blown by blower fan  202  and the cooled coolant discharged from low-temperature-side discharge pipe  107 , thereby, cooling the air. The cooled air is introduced into the vehicle interior and used for cooling the vehicle interior. 
     The coolant heated by cooling air refrigerant heat exchanger  200  is introduced into in-vehicle heat pump apparatus  1  again via low-temperature-side introduction pipe  106 . 
     Heating air refrigerant heat exchanger  201  is configured to exchange heat between the air blown by blower fan  202  and the heated coolant discharged from high-temperature-side discharge pipe  105 , thereby heating the air. The heated air is introduced into the vehicle interior and used for heating the vehicle interior. 
     The coolant cooled by heating air refrigerant heat exchanger  201  is introduced into in-vehicle heat pump apparatus  1  again via high-temperature-side introduction pipe  104 . Note that, first radiator  5  is used in heat radiation of coolant during cooling. 
     The coolant discharged from in-vehicle heat pump apparatus  1  can be used for cooling heat generating element  3 . Heat generating element  3  is a heat generating member such as a running motor used in electric vehicles, an inverter for driving a running motor, a storage battery for supplying electric energy to a running motor, a charger for charging a storage battery from the outside of a vehicle, or a DC-DC converter for voltage conversion of a storage battery. These heat generating members need to be cooled while the electric vehicle runs, for example. 
     The heat released from heat generating element  3  is absorbed by the coolant. More specifically, the coolant is heated. This heated coolant is introduced into low-temperature-side introduction pipe  106  and cooled by in-vehicle heat pump apparatus  1 . This heated coolant can be cooled by causing heat radiation of the coolant in second radiator  6 . 
     When in-vehicle air conditioning apparatus  2  is used in heating of the vehicle interior, the heat released from heat generating element  3  is absorbed by the coolant. More specifically, the coolant is heated. This heated coolant is introduced into low-temperature-side introduction pipe  106  and cooled by low-temperature-side water refrigerant heat exchanger  110 . 
     In this case, the heat recycled (absorbed) by the refrigerant can be used for heating the air in the vehicle interior by causing the high-temperature-side coolant to recycle (absorb) the heat in high-temperature-side water refrigerant heat exchanger  111 , extracting this coolant from high-temperature-side discharge pipe  105  and introducing this coolant into heating air refrigerant heat exchanger  201 . 
     As illustrated in  FIGS. 5 and 6 , the vehicle temperature adjustment system can switch between heating and cooling of the vehicle interior, for example, by switching between the passages of the coolant via a plurality of three-way valves T as well as switching between the air passages toward the vehicle interior via switching door  203 . 
     &lt;Details of High-Temperature-Side Water Refrigerant Heat Exchanger&gt; 
     Next, a detailed description will be given of the configuration of compressor casing  109  side in in-vehicle heat pump apparatus  1  of Embodiment 1. 
       FIGS. 7 and 8  are each a partially broken perspective view illustrating the configuration on the side of compressor casing of Embodiment 1.  FIG. 9  is a cross sectional view illustrating the configuration on the side of compressor casing of Embodiment 1.  FIG. 10  is a cross sectional view taken along the line D-D of  FIG. 9 . 
     High-temperature-side water refrigerant heat exchanger  111  is provided in the wall of compressor casing  109 . 
     As illustrated in  FIGS. 8 to 10 , high-temperature-side water refrigerant heat exchanger  111  includes passages  111   a  through which the refrigerant flows, and passage  111   b  through which the coolant flows. 
     Passage  111   b  for coolant is formed by a space extending in a two dimensional direction (X-R direction of  FIG. 8 ) along the circumference of electric compressor  112  and is provided with introduction port  111   b  in for coolant and outlet port  111   b  out for coolant at one end and the other end of passage  111   b , respectively. Outlet port  111   b  out communicates with high-temperature-side water pump  101 . In addition, passage  111   b  is partially formed by the wall of compressor casing  109 . 
     Passages  111   a  for refrigerant are formed of a plurality of linear and cylindrical pipes, for example, and placed in the space surrounding passage  111   b  for coolant so as to cross passage  111   b  for coolant. As illustrated in  FIG. 10 , a plurality of passages  111   a  are placed in the circumferential direction of electric compressor  112  (in direction R in  FIG. 8 ) in a distributed manner. As illustrated in  FIG. 9 , one end of each passage  111   a  communicates with refrigerant chamber  111   c  in communication with a refrigerant discharge port of electric compressor  112 , while the other end of each passage  111   a  communicates with refrigerant chamber  111   d  in communication with expansion valve  114 . Refrigerant chambers  111   c  and  111   d  are formed by the wall of compressor casing  109 . 
     With this configuration, the high-temperature and high-pressure refrigerant that has been compressed by electric compressor  112  is discharged to refrigerant chamber  111   c  from electric compressor  112  and proceeds to a plurality of passages  111   a  of high-temperature-side water refrigerant heat exchanger  111 . This high-temperature and high-pressure refrigerant thereafter is condensed by heat radiation to the coolant in high-temperature-side water refrigerant heat exchanger  111  and is sent to expansion valve  114  via refrigerant chamber  111   d.    
     As illustrated in  FIGS. 7 to 10 , high-temperature-side water refrigerant heat exchanger  111  and electric compressor  112  are configured integrally by using single compressor casing  109  as a common casing for the two devices. 
     Compressor casing  109  is sealable and encapsulates high-temperature-side water refrigerant heat exchanger  111  by the wall except for each introduction port and each discharge port for the coolant and refrigerant and also encapsulates electric motor  112   a  and compression mechanism  112   b  within the housing space of compressor casing  109 . 
     Compressor casing  109  may be regarded as separate casings for high-temperature-side water refrigerant heat exchanger  111  and electric compressor  112  by dividing the wall of compressor casing  109  into two parts and using the outer circumferential part for high-temperature-side water refrigerant heat exchanger  111  and the inner circumferential part for electric compressor  112 . In this case, as illustrated in  FIGS. 7 to 10 , high-temperature-side water refrigerant heat exchanger  111  can be regarded as surrounding the circumference of electric compressor  112  and being in contact with electric compressor  112  in a heat exchangeable manner. 
     Note that, it is actually possible to employ a configuration in which high-temperature-side water refrigerant heat exchanger  111  and electric compressor  112  are formed in separate casings, and high-temperature-side water refrigerant heat exchanger  111  surrounds the circumference of electric compressor  112  and is in contact with electric compressor  112  in a heat exchangeable manner. 
     &lt;Effects of Embodiment 1&gt; 
     According to in-vehicle heat pump apparatus  1  of Embodiment 1, the heat generated in electric compressor  112  is released into high-temperature-side water refrigerant heat exchanger  111  and mainly heats the coolant. Thus, the exhaust heat of electric compressor  112  can be effectively used. In addition, electric compressor  112  can be appropriately cooled. 
     In addition, according to in-vehicle heat pump apparatus  1  of Embodiment 1, electric motor  112   a , compression mechanism  112   b , and passages  111   a  and  111   b  of high-temperature-side water refrigerant heat exchanger  111  are housed and encapsulated in electric compressor casing  109 . Accordingly, the casing for electric compressor  112  and the casing for high-temperature-side water refrigerant heat exchanger  111  can be made common as a casing having a high strength for encapsulating a high-pressure refrigerant to prevent leakage of the high-pressure refrigerant to the outside. Thus, the number of components of in-vehicle heat pump apparatus  1  can be reduced, and the configuration of in-vehicle heat pump apparatus  1  can be made compact. 
     &lt;Details of Placement of Component Elements&gt; 
     Next, a description will be given of the placement of component elements of in-vehicle heat pump apparatus  1  of Embodiment 1. 
     Low-temperature-side water refrigerant heat exchanger  110 , accumulator  108 , and high-temperature-side water refrigerant heat exchanger  111  are placed adjacent to each other in the order named. In addition, low-temperature-side water refrigerant heat exchanger  110 , expansion valve  114 , and high-temperature-side water refrigerant heat exchanger  111  are placed adjacent to each other in the order named. The term “placed adjacent to each other in the order” refers to a placement in which accumulator  108  or expansion valve  114  exists within a space formed by a projection plane formed when low-temperature-side water refrigerant heat exchanger  110  is projected toward high-temperature-side water refrigerant heat exchanger  111 . As long as accumulator  108  or expansion valve  114  exists within a space formed by the projection plane, this term is applicable. The term “placed adjacent to each other in the order” is applicable to a placement in which accumulator  108  or valve  114  partially exists outside this space. 
       FIG. 11  is a perspective view illustrating a variation of the placement of accumulator  108 . As illustrated in  FIG. 11 , accumulator  108  small in size can be placed between low-temperature-side water refrigerant heat exchanger  110  and high-temperature-side water refrigerant heat exchanger  111 . 
     Low-temperature-side water refrigerant heat exchanger  110 , accumulator  108 , and high-temperature-side water refrigerant heat exchanger  111  are placed linearly in the order named. In addition, low-temperature-side water refrigerant heat exchanger  110 , expansion valve  114 , and high-temperature-side water refrigerant heat exchanger  111  are placed linearly in the order named. 
     The placement described above enables a configuration having a shorter passage for refrigerant in in-vehicle heat pump apparatus  1  of Embodiment 1. Furthermore, the reduction in the length of passage for refrigerant can reduce the amount of refrigerant and also can reduce a pressure loss in the flow of refrigerant, and can also reduce a heat loss from the pipes for refrigerant. 
     &lt;Structure to Fasten Compressor Casing and Low-Temperature-Side Water Refrigerant Heat Exchanger&gt; 
     Low-temperature-side water refrigerant heat exchanger  110  is held by casing (corresponding to second casing)  110   a  with a high strength for encapsulating a high pressure refrigerant (see  FIGS. 1 and 2 ). Note that, it is also possible to employ a configuration in which low-temperature-side water refrigerant heat exchanger  110  is held by a frame body instead of casing  110   a . Casing  110   a  is fastened to compressor casing  109  via fastening portion  110   b.    
     With this configuration, the three component elements including low-temperature-side water refrigerant heat exchanger  110 , high-temperature-side water refrigerant heat exchanger  111 , and electric compressor  112  can be put into a highly-rigid integrated configuration. This configuration can enhance the strength of the pipes for refrigerant between low-temperature-side water refrigerant heat exchanger  110  and compressor casing  109 . According to in-vehicle heat pump apparatus  1  of Embodiment 1, it is possible to easily achieve, with low costs, a configuration having a high strength for refrigerant having a high operation pressure. 
     Embodiment 2 
       FIG. 12  is a perspective view illustrating an in-vehicle heat pump apparatus according to Embodiment 2. 
     In-vehicle heat pump apparatus  1  of Embodiment 2 is configured to integrally house low-temperature-side water refrigerant heat exchanger  110 , high-temperature-side water refrigerant heat exchanger  111 , and electric compressor  112  in casing  100 . 
     Casing  100  is sealable. Low-temperature-side water refrigerant heat exchanger  110 , high-temperature-side water refrigerant heat exchanger  111 , and electric compressor  112  are placed in casing  100  in the same way as that of Embodiment 1. 
     Accumulator  108  is placed between low-temperature-side water refrigerant heat exchanger  110  and high-temperature-side water refrigerant heat exchanger  111  in casing  100 . 
     Note that, high-temperature-side water refrigerant heat exchanger  111  may be provided in the wall of casing  100  in the case of in-vehicle heat pump apparatus  1  of Embodiment 2. Moreover, casing  100  may be configured to serve as a casing for electric compressor  112  (shell that encapsulates refrigerant). 
     &lt;Effects of Embodiment 2&gt; 
     According to in-vehicle heat pump apparatus  1  of Embodiment 2, housing the component elements in casing  100  having sealability brings about the effect that the heat released from the component elements can be effectively utilized without being spread. In addition, placing the component elements adjacent to each other makes it possible to reduce the length of passages for connecting the component elements. Accordingly, the released amount of heat from the passages is reduced, and the effect that the heat of the component elements can be effectively utilized is brought about. 
     Furthermore, according to in-vehicle heat pump apparatus  1  of Embodiment 2, placing the component elements adjacent to each other makes it possible to reduce the length of passages for connecting the component elements, and the number of connection portions for connecting the passages for refrigerant is reduced. This brings about the effects that leakage of the refrigerant from the connection portions can be reduced, and that the number of assembly steps can be reduced. In addition, reducing the number of connection portions brings about the effect that use of a high-pressure refrigerant such as carbon dioxide refrigerant can be made easier. 
     Each embodiment of the present invention has been described thus far. 
     Note that, in the embodiments described above, the configuration using carbon dioxide as the refrigerant has been described as an example, but other various refrigerants may be used. In addition, the high-temperature-side water refrigerant heat exchanger and low-temperature-side water refrigerant heat exchanger are by no means limited to the illustrated specific configuration. 
     In addition, in the embodiments described above, a description has been given of the case where the low-temperature-side coolant and high-temperature-side coolant are not mixed even outside in-vehicle heat pump apparatus  1 . However, depending on the system configuration, it is possible to employ a configuration in which the passage for low-temperature-side coolant and the passage for high-temperature-side coolant are joined together and integrated into a single passage outside in-vehicle heat pump apparatus  1 . 
     Moreover, in the embodiments described above, a description has been given of the configuration in which the coolant pump is included in the in-vehicle heat pump apparatus as an example. However, the coolant pump can be provided to the vehicle temperature adjustment system and omit the coolant pump from the in-vehicle heat pump apparatus. 
     The disclosures of the specifications, drawings, and abstracts in Japanese Patent Application No. 2012-147613 filed on Jun. 29, 2012 and Japanese Patent Application No. 2012-179285 filed on Aug. 13, 2012 are incorporated herein by reference in their entireties. 
     INDUSTRIAL APPLICABILITY 
     The in-vehicle heat pump apparatus according to the present invention is suitable for use in a system that adjusts a temperature of each component within a vehicle, for example. 
     REFERENCE SIGNS LIST 
     
         
           1  In-vehicle heat pump apparatus 
           100  Casing 
           101  High-temperature-side water pump 
           102  Low-temperature-side water pump 
           103  Power feeding section 
           104  High-temperature-side introduction pipe 
           105  High-temperature-side discharge pipe 
           106  Low-temperature-side introduction pipe 
           107  Low-temperature-side discharge pipe 
           108  Accumulator 
           109  Compressor Casing 
           110  Low-temperature-side water refrigerant heat exchanger 
           111  High-temperature-side water refrigerant heat exchanger 
           111   a  Passage for refrigerant 
           111   b  Passage for coolant 
           112  Electric compressor 
           112   a  Electric motor 
           112   b  Compression mechanism 
           113  Inverter 
           114  Expansion valve 
           2  In-vehicle air conditioning apparatus 
           200  Cooling air refrigerant heat exchanger 
           201  Heating air refrigerant heat exchanger 
           202  Blower fan 
           3  Heat generating element 
           5  First radiator 
           6  Second radiator 
           7  Fire wall