Patent Publication Number: US-2003230395-A1

Title: Vehicle air-conditioning system

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a vehicle air-conditioning system having an evaporator and a heater core for air-conditioning the passenger&#39;s compartment of a vehicle, and more particularly to a vehicle air-conditioning system having an evaporator, a heater core, and outlet and input pipes connected to the heater core and disposed respectively above and below the evaporator.  
       [0003] 2. Description of the Related Art  
       [0004]FIG. 5 of the accompanying drawings shows a conventional vehicle air-conditioning system  100 . As shown in FIG. 5, the conventional vehicle air-conditioning system  100  adjusts the temperature and humidity of air in the passenger&#39;s compartment of a vehicle with an evaporator  102  and a heater core  104 . Specifically, the evaporator  102  cools air that passes therethrough with the heat of vaporization of an air-conditioner refrigerant. The heater core  104  heats air that passes therethrough with hot water (engine coolant water) that is heated by the engine. The hot water heated by the engine is introduced through an inlet pipe  106  into the heater core  104 , exchanges heat with the air, and discharged from the heater core  104  through an outlet pipe  108 . In typical vehicles, the engine is positioned rightward of the evaporator  102  in FIG. 5 (forward in the vehicle). Therefore, the inlet pipe  106  and the outlet pipe  108  which are connected to the heater core  104  extend in the vicinity of the evaporator  102 . The heater core  104  is connected to a radiator and shares the hot water from the engine with the radiator.  
       [0005] For adjusting both the temperature and humidity of air in the passenger&#39;s compartment, air drawn into the vehicle air-conditioning system  100  is first cooled by the evaporator  102  and then heated by the heater core  104 . In order to produce a smooth flow of air, the evaporator  102  and the heater core  104  are often disposed substantially parallel and closely to each other.  
       [0006] Since each of the evaporator  102  and the heater core  104  is a heat exchanger, they have a wide area for better heat exchange efficiency. The evaporator  102  and the heater core  104  which have a wide area are frequently vertically oriented (standing upright) due to layout limitations. The evaporator  102  should preferably be replaceable. According to some designs, the evaporator  102  has a structure slidable laterally with respect to the vehicle air-conditioning system  100 , i.e., in the directions indicated by the arrow A in FIG. 5.  
       [0007] To prevent the inlet pipe  106  and the outlet pipe  108  from interfering with the evaporator  102  as it is slid laterally, the inlet pipe  106  and the outlet pipe  108  are generally positioned so as to extend below the evaporator  102 .  
       [0008] Generally, the inlet pipe  106  is connected to a lower portion of the heater core  104 , and the outlet pipe  108  is connected to an upper portion of the heater core  104 . With this pipe layout, even when air is introduced into the inlet pipe  106  and enters the heater core  104 , since the air has a specific gravity much smaller than the engine coolant water, the air rises naturally and can be discharged from the heater core  104  into the outlet pipe  108  together with the flow of the hot water.  
       [0009] When air is trapped in the upper portion of the heater core  104 , it is discharged from the heater core  104  into the outlet pipe  108  together with the flow of the hot water. However, since the outlet pipe  108  extending from its junction  110  to the heater core  104  is directed downwardly, the air trapped in the upper portion of the heater core  104  cannot quickly be discharged through the outlet pipe  108 . The junction  110  has a complex structure including a sealing mechanism therein, so that the air may possibly stay trapped in the junction  110  for a long period of time. When the engine coolant water is replaced, air is also likely to enter the heater core  104  via the inlet pipe  106  and hence to stay trapped in the upper portion of the heater core  104 .  
       [0010] The air trapped in the vicinity of the junction  110  produces noise when the hot water flows through the junction  110 , making the passengers of the vehicle feel uncomfortable or anxious. If a large amount of air is trapped in the vicinity of the junction  110 , then the heater core  104  has its heat exchange efficiency lowered.  
       [0011] Therefore, it is necessary to remove trapped air sufficiently from the heater core  104 . For removing trapped air sufficiently from the heater core  104 , a water pump incorporated in the engine coolant water circulation system needs to be operated for a long period of time.  
       SUMMARY OF THE INVENTION  
       [0012] It is a general object of the present invention to provide a vehicle air-conditioning system which is capable of preventing air from being trapped in a heater core and allowing engine coolant water to be replaced in a short period of time.  
       [0013] A major object of the present invention is to provide a vehicle air-conditioning system which permits an evaporator to be removed easily.  
       [0014] Another object of the present invention is to provide a vehicle air-conditioning system which reduces unwanted heat dissipation and has high heat exchange efficiency.  
       [0015] According to the present invention, there is provided a vehicle air-conditioning system comprising an evaporator for cooling air passing therethrough by evaporating a refrigerant therein, a heater core for heating air passing therethrough through a heat exchange with engine coolant water heated by an engine, the heater core being substantially standing upright and having an inlet port and an outlet port, an inlet pipe for introducing the heated engine coolant water from the engine into the inlet port, an outlet pipe for discharging the engine coolant water, which has heated the air in the heater core, from the outlet port, the outlet port being positioned upwardly of the inlet port, the outlet pipe being connected to the outlet port and directed horizontally or upwardly from the outlet port, the outlet pipe extending over the evaporator and being connected to the engine.  
       [0016] Because the outlet pipe connected to the outlet port is directed horizontally or upwardly from the outlet port, air is less likely to be trapped in the heater core, and the engine coolant water can be replaced in a short period of time. As the outlet pipe extends over the evaporator and is connected to the engine, the outlet pipe does not obstruct the replacement of the evaporator.  
       [0017] The inlet pipe may be connected to the inlet port and directed horizontally or downwardly from the inlet port, and the inlet pipe may extend below the evaporator and be connected to the engine. With this arrangement, air does not tend to be trapped in the inlet pipe, and the inlet pipe does not obstruct the replacement of the evaporator.  
       [0018] If the evaporator is substantially standing upright, then the evaporator and the heater core are disposed substantially parallel to each other, allowing air for being adjusted in temperature to pass easily therethrough.  
       [0019] If the outlet pipe is covered at least partly with an insulation member, then unwanted thermal dissipation is reduced, and heat exchange efficiency is increased.  
       [0020] The inlet pipe or the outlet pipe may be covered at least partly with a protective cover.  
       [0021] If the outlet pipe comprises a bent metal pipe, then the engine coolant water and any trapped air can easily flow through the outlet pipe, so that trapped air is quickly discharged by the flow of the engine coolant air.  
       [0022] If the engine coolant water is poured through a coolant water inlet disposed at a position higher than an uppermost portion of the outlet pipe, then the engine coolant water can reliably fill up the heater core, the inlet pipe, and the outlet pipe.  
       [0023] The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0024]FIG. 1 is a vertical cross-sectional view of a vehicle air-conditioning system according to the present invention and parts associated therewith;  
     [0025]FIG. 2 is a perspective view of the vehicle air-conditioning system;  
     [0026]FIG. 3 is a perspective view of a heater core, an inlet pipe, and an outlet pipe of the vehicle air-conditioning system;  
     [0027]FIG. 4 is a front view of the heater core, an end of the inlet pipe, and an end of the outlet pipe of the vehicle air-conditioning system; and  
     [0028]FIG. 5 is a perspective view of an evaporator, a heater core, an inlet pipe, and an outlet pipe of a conventional vehicle air-conditioning system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0029] A vehicle air-conditioning system according to an embodiment of the present invention will be described below with reference to FIGS. 1 through 4.  
     [0030] As shown in FIG. 1, a vehicle air-conditioning system  10  according to the embodiment of the present invention serves to adjust the temperature and humidity of air in a passenger&#39;s compartment of a vehicle  12 , and is disposed within a front console  14  of the vehicle  12 . The vehicle air-conditioning system  10  has a blower fan (not shown) for selectively supplying internal air or external air, an evaporator  16  for cooling and dehumidifying air supplied from the blower fan by evaporating a refrigerant, a heater core  20  for heating air through a heat exchange with coolant water from an engine  18 , an inlet pipe  22  for introducing hot water from the engine  18  into the heater core  20 , and an outlet pipe  24  for delivering hot water, which has heated air, from the heater core  20  to the engine  18 . The inlet pipe  22  extends below the evaporator  16  and is connected to the engine  18 . The outlet pipe  24  extends over the evaporator  16  and is connected to the engine  18 . The hot water means coolant water heated by the waste heat generated by the engine  18 . In the description which follows, engine coolant water at a low temperature will be referred to as “engine coolant water” and engine coolant water at a high temperature as “hot water”.  
     [0031] The vehicle air-conditioning system  10  also has a compressor, a condenser, and an expansion valve (not shown). The refrigerant which is evaporated by the evaporator  16  is compressed by the compressor and then liquefied by the condenser. The liquefied refrigerant is converted by the expansion valve into a mist which returns to the evaporator  16  for circulation.  
     [0032] The vehicle air-conditioning system  10  also has an air mixing door  26  for adjusting the amount of air that has passed through the evaporator  16  and which is to be introduced into the heater core  20 , and two selector doors  32 ,  34  for selecting three air outlets, i.e., a defroster outlet  28 , a face outlet  29 , and a foot outlet  30 , by changing air passages.  
     [0033] Air supplied from the blower fan is introduced into a space  33  in front of the evaporator  16 , flows through the evaporator  16 , and is controlled in direction by the air mixing door  26 . Part or all of the air is introduced into the heater core  20  by the air mixing door  26  depending on its opening. When the air mixing door  26  is fully closed, the air is blocked from entering into the heater core  20 .  
     [0034] When the air mixing door  26  is fully opened, all of the air that has passed through the evaporator  16  is introduced into the heater core  20 . After having passed through the heater core  20 , the air flows upwardly through a first air passage  36  into a space  37  at an outlet of the first air passage  36 . When the air mixing door  26  is fully closed, the air that has passed through the evaporator  16  is not supplied to the heater core  20 , but directly supplied to the space  37 . From the space  37 , the air is delivered into the passenger&#39;s compartment from the defroster outlet  28  and/or the face outlet  29  by the selector doors  32 ,  34  depending on their opening. Depending on the opening of the selector doors  32 ,  34 , part or all of the air is introduced into a second air passage  38 , from which the air is delivered into the passenger&#39;s compartment through the foot outlet  30 . Specifically, the air introduced into the defroster outlet  28  is delivered through a duct  40  toward a front windshield  41 . The air introduced into the face outlet  29  is delivered through a duct  42  and a ventilation grill  44  into the passenger&#39;s compartment. The air introduced into the foot outlet  30  is delivered through a duct (not shown) toward the feet of the passenger.  
     [0035] The second air passage  38  of the vehicle air-conditioning system  10  is partly defined by a partition comprising a thin resin panel  46 . A radio unit  48  mounted on the front console  14  is positioned near the resin panel  46  at its surface facing the passenger&#39;s compartment. The resin panel  46  is molded of polypropylene, for example.  
     [0036] As shown in FIG. 2, the inlet pipe  22  is covered at least partly with a first protective cover  50  and a second protective cover  52  which are made of synthetic resin. The outlet pipe  24  is covered at least partly with an insulation member  54 . The first protective cover  50 , the second protective cover  52 , and the insulation member  54  serve to prevent persons (passengers or maintenance personnel) from directly touching the inlet pipe  22  and the outlet pipe  24  inadvertently. If the first protective cover  50  and the second protective cover  52  are made of a thermal insulation, then unwanted heat dissipation is reduced, and the heater core  20  has high heat exchange efficiency.  
     [0037] The resin panel  46  has a grid-like pattern of vertical and horizontal grooves  58  defined in a peripheral region of its surface  56  close to the radio unit  48  (see FIG. 1). The resin panel  46  has a sufficient thickness in the grooves  58  for providing desired mechanical strength to the resin panel  46  for resistance against vibrations and fatigue while the vehicle is running normally.  
     [0038] The resin panel  46  also has a plurality of blocks  60  surrounded by the grooves  58  in the grid-like pattern. The surface  56  of the resin panel  46  has a protrusion  62  disposed substantially centrally thereon at an area closest to the radio unit  48 .  
     [0039] As shown in FIG. 3, the inlet pipe  22  has an end  22 a connected to an inlet port  70  on a lowermost portion of a side panel of the heater core  20 . The end  22 a connected to the inlet port  70  lies horizontally. Alternatively, the end  22   a  connected to the inlet port  70  may be directed downwardly from the horizontal plane. The outlet pipe  24  has an end  24 a connected to an outlet port  72  on an uppermost portion of the side panel of the heater core  20 . The end  22   a  connected to the inlet port  70  extends upwardly from the outlet port  72 . The end  22   a  connected to the inlet port  70  may be directed upwardly from the horizontal plane.  
     [0040] As shown in FIG. 4, hot water flowing from the inlet port  70  into the heater core  20  is introduced into a lower passage  74  defined in and extending along a lower side of the heater core  20 , and then flows upwardly through a plurality of vertical thin pipes  76  connected to the lower passage  74 . The hot water which flows upwardly enters an upper passage  78  defined in and extending along an upper side of the heater core  20 , and then is discharged from the outlet port  72  into the outlet pipe  24 .  
     [0041] A plurality of wavy fins  80  are interposed between the thin pipes  76  and contact the thin pipes  76 . Air to be adjusted in temperature by the vehicle air-conditioning system  10  is heated when it flows across the heater core  20  through the gaps between the fins  80 .  
     [0042] As described above, the vehicle air-conditioning system  10  heats air through a heat exchange with the heater core  20  using the waste heat from the engine  18  in order to heat the air in the vehicle  12 . The engine coolant water for introducing the waste heat from the engine  18  into the heater core  20  comprises water or a dedicated liquid. The engine coolant water is heated by the engine  18  into hot water, which is supplied to the heater core  20  and a radiator (not shown) by a water pump (not shown). The engine coolant water should preferably be replaced with fresh engine coolant water at predetermined time intervals.  
     [0043] A process of replacing the engine coolant water in the heater core  20  of the vehicle air-conditioning system  10  will be described below with reference to FIG. 4.  
     [0044] For replacing the engine coolant water, a drain cock (not shown) on the heater core  20  is opened to discharge the engine coolant water from the heater core  20 . The engine coolant water is now drained from the heater core  20 , the inlet pipe  22 , and the outlet pipe  24 , drawing air into the heater core  20 . After the engine coolant water is discharged, the drain cock is closed.  
     [0045] Then, fresh engine coolant water is poured in from a coolant water inlet of the engine coolant water circulation system, e.g., a radiator inlet port. The poured engine coolant water first fills the lower inlet pipe  22 . Since the end  22   a  of the inlet pipe  22  is horizontally connected to the inlet port  70  on the heater core  20 , the inlet pipe  22  and the end  22   a  are filled with the engine coolant water with no air trapped therein.  
     [0046] Then, the poured engine coolant water flows from the inlet port  70  into the heater core  20 , and rises in water level through the lower passage  74 , the thin pipes  76 , and the upper passage  78 .  
     [0047] After having filled the upper passage  78 , the engine coolant water flows from the outlet port  72  into the outlet pipe  24 . Because the end  24   a  of the outlet pipe  24  which is connected to the outlet port  72  is directed upwardly from the outlet port  72 , no air is trapped in the end  24   a , allowing the engine coolant water to rise in level smoothly in the end  24   a .  
     [0048] When the engine coolant water rises in level in the end  24   a  of the outlet pipe  24 , it also rises in level in an opposite end  24   b  (see FIG. 3) of the outlet pipe  24 . Therefore, air is trapped in an uppermost portion  24   c  of the outlet pipe  24 , which is positioned between the ends  24   a ,  24   b , and remains trapped in the uppermost portion  24   c.    
     [0049] When the engine coolant water circulation system is filled with the engine coolant water up to the end of the coolant water inlet, the pouring of the engine coolant water is stopped.  
     [0050] Then, the water pump is actuated to circulate the poured fresh engine coolant water to remove the trapped air, i.e., to bleed the engine coolant water circulation system. When the water pump is actuated, the engine coolant water flows from the inlet port  70  into the lower passage  74 , then through the thin pipes  76  into the upper passage  78 , from which the engine coolant water flows through the outlet port  72  into the outlet pipe  24 . In the vicinity of the outlet port  72 , a small amount of trapped air in a constricted passage  82  and a joint gap  84 , which are positioned between the upper passage  78  and the outlet port  72 , is carried by the flow of the engine coolant water into the outlet pipe  24 . At this time, the trapped air moves with the flow of the engine coolant water. After the trapped air has reached the end  24   a  of the outlet pipe  24 , it is discharged upwardly naturally due to the difference between the specific gravity of the air and the specific gravity of the engine coolant water. As the constricted passage  82  and the joint gap  84  are spaced from the end  24   a  by a small distance, the trapped air can easily move to the end  24   a . Therefore, even if the flow of the engine coolant water contains turbulent streams or vortexes, the trapped air can quickly be discharged. Even if part of the trapped air in the vicinity of the outlet port  72  is not discharged, its amount is very small.  
     [0051] A relatively large amount of air is initially trapped in the uppermost portion  24   c  (see FIG. 3) of the outlet pipe  24  when the fresh engine coolant water is introduced. However, the trapped water is quickly discharged from the uppermost portion  24   c  when the engine coolant water is circulated by the water pump. The reason why the trapped water is quickly discharged from the uppermost portion  24   c  is as follows: The outlet pipe  24  is in the form of a bent metal pipe having a smooth inner surface free of projections and steps for allowing the engine coolant water and the trapped air to flow smoothly. Accordingly, the trapped water is quickly discharged by the flow of the engine coolant water from the outlet pipe  24 .  
     [0052] Since no air is trapped in the inlet pipe  22  and the end  22   a  thereof, no new air finds its way into the heater core  20 . Even if a small amount of air exists in the inlet pipe  22  or a portion of the engine coolant water circulation system which precedes the inlet pipe  22 , the air is quickly discharged through the outlet port  72  and the outlet pipe  24 .  
     [0053] The air discharged from the outlet pipe  24  reaches the coolant water inlet, lowering the level of the engine coolant water in the coolant water inlet. The engine coolant water is supplied again to raise the level of the engine coolant water in the coolant water inlet, whereupon the engine coolant water replacing process including the bleeding process is finished.  
     [0054] As described above, when fresh engine coolant water is poured into the vehicle air-conditioning system  10  to replace the old engine coolant water, the amount of any initially trapped water is very small. A small amount of water which may be trapped in the constricted passage  82  and the joint gap  84  can quickly be discharged when the poured engine coolant water is circulated. As no projections and steps are present on the inner surface of the outlet pipe  24 , an amount of water trapped in the uppermost portion  24   c  of the outlet pipe  24  is quickly discharged by the circulation of the poured engine coolant water. Therefore, the bleeding process, in particular, of the engine coolant water replacing process can be carried out in a short period of time.  
     [0055] Inasmuch as no trapped water is present in the vicinity of the outlet port  72 , noise due to trapped air is not produced when hot water flows through the outlet port  72  when the vehicle air-conditioning system  10  is in operation. Even if trapped air remains in the vicinity of the outlet port  72 , its amount is so small that no noise is produced. The heater core  20  is capable of exchanging heat highly efficiently as no trapped air remains therein.  
     [0056] Even if trapped air remains in the uppermost portion  24   c  of the outlet pipe  24 , since the inner surface of the outlet pipe  24  is smooth, basically no noise is produced when the trapped air moves along the smooth inner surface of the outlet pipe  24 .  
     [0057] Because the inlet pipe  22  extends below the evaporator  16  and the outlet pipe  24  extends above the evaporator  16 , when the evaporator  16  is slid laterally, its sliding movement is not obstructed by the inlet pipe  22  and the outlet pipe  24 . Accordingly, the evaporator  16  can easily be replaced.  
     [0058] The coolant water inlet for pouring the engine coolant water therethrough may be located at a position higher than the uppermost portion  24   c  of the outlet pipe  24 , so that the heater core  20 , the inlet pipe  22 , and the outlet pipe  24  can reliably be filled with the engine coolant water. The coolant water inlet may be positioned on the uppermost portion  24   c  of the outlet pipe  24 .  
     [0059] Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.