Abstract:
An air-conditioning unit comprises a compressor component for compressing a refrigerant, a condenser component for condensing the refrigerant, and an evaporator component for evaporating the refrigerant. At least two of the compressor, the condenser and the evaporator components is assembled integrally. This prevents with certainty leakage of the refrigerant that circulates through the air-conditioning unit.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to an air-conditioning unit.  
           [0002]    Recently, various low-pollution vehicles have been developed as a response to environmental problems. Electric vehicles, one type of low-pollution vehicles, have been developed actively and put to practical use. Each electric vehicle runs a drive motor using a battery as the energy source. A motor-driven compressor, which uses an electric motor as the drive source, is used as a compressor for an air-conditioning systems in electric vehicles.  
           [0003]    For example, Japanese Unexamined Patent Publication (KOKAI) No. Hei 8-216671 discloses an air-conditioning system that uses a motor-driven compressor as shown in FIG. 7.  
           [0004]    A case  52  of an air-conditioning system  51  houses a condenser  53 , an evaporator  54  and a motor-driven compressor  55 . The case  52  is divided into first, second and third chambers  60 ,  70  and  80 . The first chamber  60  accommodates the condenser  53 , the second chamber  70  accommodates the evaporator  54 , and the third chamber  80  accommodates a horizontal type motor-driven compressor  55  and a four-way valve  56 . The condenser  53 , the evaporator  54 , the motor-driven compressor  55  and the four-way valve  56  are connected together by pipes  57   a  to  57   d,  which form a passage for a refrigerant gas. A motor-driven expansion valve  58  is provided on the pipe  57   c  that connects the condenser  53  to the evaporator  54 .  
           [0005]    In consideration of environmental problems, carbon dioxide has recently been used as a refrigerant. In this case, the pressure inside each of the pipes  57   a - 57   d  is higher than that where chlorofluorocarbon, or freon, is used as a refrigerant. This causes refrigerant gas to leak through the joint sections of the pipes  57   a - 57   d.  When the pipes are long, the probability of cracks and other kinds of damage increases. Such damages including cracks will result in leakage of the refrigerant gas.  
         SUMMARY OF THE INVENTION  
         [0006]    Accordingly, it is an object of the present invention to provide a compact air-conditioning unit that prevents with certainty leakage of the refrigerant that circulates through the air-conditioning unit.  
           [0007]    To achieve the above objective, the present invention provides an air-conditioning unit. The air-conditioning unit comprises a compressor component for compressing a refrigerant, a condenser component for condensing the refrigerant, and an evaporator component for evaporating the refrigerant. At least two of the compressor, the condenser and the evaporator components are assembled integrally. 
       
    
    
       [0008]    Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:  
         [0010]    [0010]FIG. 1 is a perspective view of an air-conditioning unit according to a first embodiment of the present invention;  
         [0011]    [0011]FIG. 2 is a partial cross-sectional view showing a passage that connects a motor-driven compressor to a condenser;  
         [0012]    [0012]FIG. 3 is a perspective view of an air-conditioning unit according to a second embodiment of the present invention;  
         [0013]    [0013]FIG. 4 a  is a plan view of the section where the motor-driven compressor is connected to an evaporator;  
         [0014]    [0014]FIG. 4 b  is a plan view of the section where the condenser is connected to the evaporator;  
         [0015]    [0015]FIG. 5 is a perspective view illustrating a unified assembly of a motor-driven compressor and a condenser according to a third embodiment of the present invention;  
         [0016]    [0016]FIG. 6 is a perspective view of an air-conditioning unit according to a fourth embodiment of the present invention; and  
         [0017]    [0017]FIG. 7 is a cross-sectional view of a conventional air-conditioning system. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    A first embodiment of an air-conditioning unit  1  of a vehicle air-conditioning system will be described with reference to FIGS. 1 and 2.  
         [0019]    As shown in FIG. 1, the air-conditioning unit  1  is installed in, for example, the engine compartment of an automobile. The air-conditioning unit  1  has a motor-driven compressor  2  which compresses refrigerant, a condenser  3 , which condenses the refrigerant, and an evaporator  4 , which evaporates the refrigerant. The motor-driven compressor  2  has a compressing mechanism  5 , a motor  6  and a drive circuit  7 . The drive circuit  7  controls the rotational speed of the motor  6 . The discharge capacity of the compressing mechanism  5  is changed in accordance with the rotational speed of the motor  6 . The discharged refrigerant flows from the motor-driven compressor  2  to the condenser  3  and from the condenser  3  to the evaporator  4 . Then the refrigerant returns to the motor-driven compressor  2 .  
         [0020]    Four brackets  8  (three shown in FIG. 1) are integrally formed on a housing  2   a  of the motor-driven compressor  2 . The motor-driven compressor  2  is attached to the condenser  3  by the brackets  8  by unillustrated bolts. A first connector  9 , where a first pipe  17   a,  including a pipe and hose, is attached, is provided on one end surface of the compressing mechanism  5 . Formed in the first connector  9  is an inlet port  10 , which communicates with a suction chamber (not shown) in the compressing mechanism  5 .  
         [0021]    The condenser  3  is provided with a gas-liquid separator  11 . The condenser  3  is also provided with a second connector  12 , where a second pipe  17   b  is attached. Formed in the second connector  12  is a discharge port  13 , from which refrigerant that has been separated by the gas-liquid separator  11  after condensation in the condenser  3  is discharged.  
         [0022]    The evaporator  4  is provided with a third connector  14 , where end portions of the pipes  17   a  and  17   b  are attached. Formed in the third connector  14  are an inlet port  15 , from which the refrigerant enters, and a exhaust port  16 , from which the refrigerant gas evaporated by the evaporator  4  is exhausted. The discharge port  13  of the condenser  3  and the inlet port  15  of the evaporator  4  are connected together by the second pipe  17   b.  The exhaust port  16  of the evaporator  4  and the inlet port  10  of the motor-driven compressor  2  are connected together by the first pipe  17   a.  An expansion valve  18  is provided on the second pipe  17   b.  A blower fan  19  is located near the evaporator  4 . The blower fan  19  and the evaporator  4  are located in a duct  20 .  
         [0023]    A discharge pipe section  21  is integrally formed on one end surface of the compressing mechanism  5 . The discharge pipe section  21  communicates with a discharge chamber (not shown) in the compressing mechanism  5 . The condenser  3  has an inlet pipe section  22  integrally formed at a position corresponding to the discharge pipe section  21 . The discharge and inlet pipe sections  21  and  22  are connected together by a nipple  23 . The discharge and inlet sections  21  and  22  and the nipple  23  form a passage  24 . The motor-driven compressor  2  is connected to the condenser  3  via the passage  24 .  
         [0024]    [0024]FIG. 2 shows the cross section of the passage  24  that connects the motor-driven compressor  2  to the condenser  3 . Formed on the inner surfaces of the distal end portions of the pipe sections  21  and  22  are internal threads  21   a  and  22   a,  which are threaded in opposite directions. Formed on the outer surfaces of the ends of the nipple  23  are external threads  23   a  and  23   b,  which are respectively threaded to the internal screws  21   a  and  22   a.  When the external threads  23   a  and  23   b  of the nipple  23  are threaded into their respective internal screws  21   a  and  22   a,  the two pipe sections  21  and  22  are connected together by the nipple  23 . A discharge port  25  of the pipe section  21  is connected to an inlet port  27  of the pipe section  22  via a communication hole  26  formed in the nipple  23 .  
         [0025]    Since the pipe sections  21  and  22  are connected together by the nipple  23 , this embodiment does not use a pipe or a hose. Therefore, the joint in the passage  24  where high pressure refrigerant gas, discharged from the motor-driven compressor  2  enters the condenser  3  is essentially nothing more than the nipple  23 .  
         [0026]    This embodiment has the following advantages.  
         [0027]    Because the motor-driven compressor  2  is integrally attached to the condenser  3 , the distance between the inlet port  10  of the motor-driven compressor  2  and the discharge port  13  of the condenser  3  is short. It is therefore possible to employ a structure in which both pipe sections  21  and  22  extend respectively from the motor-driven compressor  2  and the condenser  3  so that the pipe sections  21  and  22  are directly coupled together.  
         [0028]    Since both pipe sections  21  and  22  are directly coupled together, damage including cracks are reduced significantly compared with the case where a pipe or a hose is used. According to the illustrated embodiment, there is only one joint. If a pipe or a hose is required, two joints, one at each end of the hose or pipe, are required. This reliably prevent leakage of the refrigerant gas.  
         [0029]    The unified motor-driven compressor  2  and condenser  3  can be treated as a single component. This makes it easier to install the air-conditioning unit  1  in a vehicle and reduces the installation space required for the air-conditioning unit  1 .  
         [0030]    The passage  24  where the refrigerant gas under high pressure, discharged from the motor-driven compressor  2 , travels is not joined to a pipe. It is therefore possible to prevent refrigerant leakage where refrigerant leakage is most likely to occur. When the present invention is used in the air-conditioning unit  1 , which uses carbon dioxide as the refrigerant, particularly, refrigerant leakage can be reliably prevented.  
         [0031]    The air-conditioning unit  1  according to a second embodiment of the present invention will be discussed below with reference to FIGS.  3  to  4 B. This embodiment differs from the embodiment illustrated in FIGS. 1 and 2 in that the motor-driven compressor  2  is attached to the condenser  3  and the evaporator  4  to provide an integral air-conditioning unit  1  and is the same as the latter embodiment in other respects. To avoid a redundancy, like or same reference symbols are given to those components that are like or the same as corresponding components of the first embodiment.  
         [0032]    As shown in FIG. 3, the motor-driven compressor  2  is attached integrally to the condenser  3  via the brackets  8  by unillustrated bolts. The motor-driven compressor  2  is connected to the condenser  3  by the passage  24 , which is formed by directly coupling the pipe sections  21  and  22  to each other with the nipple  23 . The housing  2   a  of the motor-driven compressor  2  has four second brackets  31  (only two are shown in FIG. 3) formed at positions corresponding to the first brackets  8 . The motor-driven compressor  2  is attached to the evaporator  4  by the four second brackets  31  by unillustrated bolts. The motor-driven compressor  2 , the condenser  3  and the evaporator  4  are therefore unified.  
         [0033]    The structure that connects the exhaust port  16  of the evaporator  4  to the inlet port  10  of the motor-driven compressor  2  is essentially identical to the structure that connects the discharge port  13  of the condenser  3  to the inlet port  10  of the motor-driven compressor  2  in the embodiment illustrated in FIGS. 1 and 2. Specifically, as shown in FIG. 4( a ), a downstream pipe section  32  is integrally formed on one end surface of the compressing mechanism  5  of the motor-driven compressor  2 . An upstream pipe section  33  is integrally formed on one side of the evaporator  4  at the position that corresponds to the downstream pipe section  32 . When the nipple  23  is fastened between the two pipe sections  32  and  33 , the inlet port  10  and the exhaust port  16  are connected without using a pipe or hose.  
         [0034]    The structure that connects the discharge port  13  of the condenser  3  to the inlet port  15  of the evaporator  4  is likewise essentially the same as the structure that uses the nipple  23 . Specifically, as shown in FIG. 4( b ), an upstream pipe section  34  is formed on one side of the condenser  3 . A downstream pipe section  35  is formed on one side of the evaporator  4  at a position that corresponds to the upstream pipe section  34 . When the nipple  23  is fastened between the two pipe sections  34  and  35 , the discharge port  13  and the inlet port  15  are connected without using a pipe or a hose. The expansion valve  18  is located in the fourth pipe section  35 .  
         [0035]    According to this embodiment, like the embodiment shown in FIGS. 1 and 2, the motor-driven compressor  2  and the condenser  3  are connected together without a pipe and refrigerant leakage is prevented. Further, the assembly of the air-conditioning unit  1  is simple and the installation space required for the unit  1  is small.  
         [0036]    The unitary assembly of the motor-driven compressor  2 , the condenser  3  and the evaporator  4  shorten the distances between all the joint sections. This makes it possible to connect all the motor-driven compressor  2 , the condenser  3  and the evaporator  4  without pipes or hoses. This considerably reduces the likelihood of damage, including cracks in the pipes. Since there are only three joints in the air-conditioning unit  1 , refrigerant leakage are further prevented. Furthermore, the air-conditioning unit  1  of this embodiment is more compact than that of the embodiment shown in FIGS. 1 and 2, thus requiring a smaller installation space.  
         [0037]    The embodiment may be modified as follows.  
         [0038]    For example, the motor-driven compressor  2  and the condenser  3  may be connected by a pipe  41  as in the third embodiment shown in FIG. 5. In this case, the discharge port  25  of a first connector  42  formed on the motor-driven compressor  2  is connected to the inlet port  27  of a second connector  43  formed on the condenser  3  by the pipe  41 . The unitary assembly of the motor-driven compressor  2  and the condenser  3  reduces the length of the pipe  41 . This reduces the likelihood of damage, including cracks in the pipe  41 , thus preventing of refrigerant leakage more reliably.  
         [0039]    Further, the motor-driven compressor  2  and the evaporator  4  may be assembled integrally, and the inlet port of the motor-driven compressor  2  may be connected to the exhaust port of the evaporator  4  without using a pipe as in a fourth embodiment shown in FIG. 6. In this embodiment, the discharge chamber is provided in the inner portion of the compressing mechanism  5 , and the suction chamber is in the outer portion of the compressing mechanism  5 . A pipe section  44  extending from one side of the evaporator  4  and a pipe section  45  extending from one end surface of the motor-driven compressor  2  are connected together by the nipple  23 . The pipe sections  44  and  45  and the nipple  23  form a passage  47 . The discharge port  25  of the motor-driven compressor  2  and the inlet port  27  of the condenser  3  are connected by a pipe  46   a,  and the discharge port  13  of the condenser  3  and the inlet port  15  of the evaporator  4  are connected by a pipe  46   b.  This removes the pipe between the motor-driven compressor  2  and the evaporator  4 , thus improving the prevention of refrigerant leakage from the refrigerant passage between the motor-driven compressor  2  and the evaporator  4 . The inlet port of the motor-driven compressor  2  and the exhaust port of the evaporator  4  may however be connected by a pipe. Because the length of the pipe that connects the exhaust port to the inlet port is shorter in this case too, the prevention of refrigerant leakage from the refrigerant passage between the motor-driven compressor  2  and the condenser  3  is improved.  
         [0040]    At the time of connecting the unitary motor-driven compressor  2 , condenser  3  and evaporator  4  in the air-conditioning unit  1 , a choice can be made between connecting those components  2  to  4  with or without pipes.  
         [0041]    The nipple  23  may be omitted. For example, the nipple  23  may be replaced with a structure in which one pipe section is fitted into the other pipe section and a lock nut is fastened on a external screw formed on the outer surface of the outer pipe section.  
         [0042]    If the motor-driven compressor  2 , the condenser  3  and the evaporator  4  are unitary as in the embodiment shown in FIGS.  3  to  4 B, the means of the unification is not limited to the attachment of the components themselves. For example, the condenser  3  to which the motor-driven compressor  2  is attached and the evaporator  4  may be attached to a common support base or a common case.  
         [0043]    The position and direction of the attachment of the motor-driven compressor  2  to the condenser  3  are variable as are the position and direction of the attachment of the motor-driven compressor  2  to the evaporator  4 .  
         [0044]    The compressor is not limited to the motor-driven compressor  2 . For example, it is possible to employ a compressor that uses an external power source, such as an engine, as the drive source. Further, a reciprocal type compressor (e.g., a swash-plate type compressor or the like) or a rotary compressor (e.g., a scroll type compressor or the like) may be selected as needed.  
         [0045]    The air-conditioning unit  1  of the present invention is not necessarily be installed in a vehicle (automobile), but may be adapted to a building air-conditioning system.  
         [0046]    It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Particularly, it should be understood that the invention may be embodied in the following forms.  
         [0047]    Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims.