Patent Publication Number: US-2002000309-A1

Title: Heat exchanger having superheated coolant bypass passage

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a vehicular heat exchanger including a laminated type evaporator; and, more particularly, to a heat exchanger capable of reducing friction resistance to a coolant fluid flowing therein and improving the efficiency of a heat exchanging performance by employing a superheated coolant bypass passage that allows superheated coolant gas to bypass a heat-exchanging region.  
       BACKGROUND OF THE INVENTION  
       [0002] In general, an evaporator for use in vehicle air conditioners includes a coolant inlet, a coolant outlet and a coolant flow passage formed therebetween. Heat exchange is performed when a coolant circulates through the coolant flow passage.  
       [0003] Referring to FIG. 1, there is provided a conventional vehicular heat exchanger having a structure as described above. The heat exchanger includes a coolant flow passage  102  formed by stacking a plurality of laminated plates  101 , cooling fins  103  installed between the laminated plates  101 , and a tank part  106  installed on top of the laminated plates  101  and connected to a coolant inlet  104  and a coolant outlet  106 . A coolant is introduced to the tank part  106  through the coolant inlet  104  and circulates through patterns of the flow passage  102  formed on each of the laminated plates  101 . When the coolant travels through the flow passages  102 , heat is exchanged between the cooling fins  103  and air flow generated by a blower prepared at one side of the heat exchanger. When the heat exchanging process is completed, the coolant is converted to superheated gas and transferred to an air compressor through the coolant outlet  105 .  
       [0004] However, this conventional heat exchanger presents certain drawbacks. When the coolant in a liquid state absorbs the heat by circulating the flow passages, some of the coolant is changed into gas or superheated gas and cannot absorb the heat any more. Nevertheless, the coolant in the gas or the superheated gas state still remains in the heat-exchanging region, thereby reducing an effective area of the heat exchanging process and deteriorating the efficiency of the evaporator. Further, since a volume of the coolant increases when the coolant undergoes a phase change from a liquid state to a gas state, resistance of the coolant traveling through the flow passage is also increased and the efficiency of the heat exchanger is greatly reduced.  
       SUMMARY OF THE INVENTION  
       [0005] It is, therefore, an object of the present invention to provide a heat exchanger capable of reducing resistance against a coolant traveling through a flow passage and increasing an effective heat-exchanging area.  
       [0006] In accordance with the present invention, there is provided a heat exchanger including a flow passage  2  formed by stacking a plurality of laminated plates  1 , cooling fins  3  installed between the plates  1 , and a tank part  6  prepared on top of the plates  1  and connected to a coolant inlet  4  and a coolant outlet  5 , wherein the tank part  6  has a bypass means for allowing the coolant in a gas state to move toward the coolant outlet  5  without returning to the flow passage  2 . 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0007] The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:  
     [0008]FIG. 1 is a perspective view of a conventional heat exchanger;  
     [0009]FIG. 2 provides a perspective view of a heat exchanger in accordance with a preferred embodiment of the present invention; and  
     [0010]FIG. 3 depicts a schematic diagram for illustrating an operational state of the heat exchanger in accordance with a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0011] Referring to FIG. 2, there is shown a heat exchanger in accordance with a preferred embodiment of the present invention. The heat exchanger includes a passage  2  formed by stacking a plurality of laminated plates  1 , cooling fins  3  installed between the plates  1 , a tank part  6  formed on top of the plates  1  and connected to a coolant inlet  4  and a coolant outlet  5 . Further, bypass holes  7  are formed on upper portion of the tank part  6  in a zigzag pattern.  
     [0012] An operation of the heat exchanger in accordance with the present invention will be described hereinafter with reference to FIG. 3.  
     [0013] A coolant in a liquid state provided to the tank part  6  through the coolant inlet  4  circulates through the flow passage  2  patterned on the laminated plates  1  and absorbs heat from air flowing around the cooling fins  3 . During this heat-exchanging process, some of the liquid coolant becomes gas or superheated gas. Since the coolant in the superheated gas state has a smaller density than the coolant in the liquid state, the superheated coolant gas rises upward to the tank part  6  and moves to the coolant outlet  5  through the bypass holes  7  without invading the flow passage where the heat exchange is being performed. Accordingly, it becomes possible that only the coolant in the liquid state flows in the heat-exchanging region such that the flow resistance of the coolant can be reduced and the efficiency of the heat exchange can be greatly improved.  
     [0014] In accordance with another embodiment of the present invention, an upper portion of the tank part  6  is expanded and the coolant in the liquid state flows at a bottom portion of the tank part  6 . The coolant in the gas state transferred to the tank part  6  from the flow passage  2  flows through the expanded upper portion of the tank part  4  and moves toward the coolant outlet  5  without returning to the flow passage  2 . Thus, the same effects as described above can be obtained.  
     [0015] As described above, the heat exchanger in accordance with the present invention includes a means for allowing a coolant in a superheated gas state to bypass a flow passage where heat exchange is being performed. Thus, resistance to the coolant flow and heat loss in the heat exchanging process can be reduced. Further, the efficiency of the heat exchanger can be greatly improved and an overload of the air compressor can be prevented.  
     [0016] While the invention has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes and modifications may by made without departing from the spirit and scope of the invention as defined in the following claims.