Patent Publication Number: US-7222502-B2

Title: Expansion valve

Description:
The present application is based on and claims priority of Japanese patent application No. 2004-36866 filed on Feb. 13, 2004, the entire contents of which are hereby incorporated by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an expansion valve equipped in an air conditioner of a car or the like for controlling the flow of refrigerant supplied to an evaporator according to the temperature of the refrigerant. 
   2. Description of the Related Art 
   This type of expansion valve is disclosed for example in the following patent document, Japanese Patent Application Laid-Open Publication No. 2000-304381. 
   The prior art expansion valve included a valve receive member, a spring, an adjustment screw and so on, which required a large number of components, so it was difficult to achieve the desired reduction in weight and size of the expansion valve. 
   Furthermore, there was fear that the refrigerant might leak from the valve chamber through the adjustment screw portion. 
   SUMMARY OF THE INVENTION 
   In view of the above drawbacks, the present invention aims at answering to the demands for reducing the size and weight of the car air conditioner by providing an expansion valve having a simplified structure and therefore requiring less assembling steps. 
   The expansion valve according to the present invention comprises a valve body, a power element portion disposed on an upper end of the valve body for actuating a valve means in response to a displacement of a diaphragm, and a spring disposed within a valve chamber formed to a lower end of the valve body for adjusting a valve opening of the valve means, wherein the spring is supported by a sealing member inserted to an opening of the valve chamber and fixed to the valve body via a crimping portion. The expansion valve further has a stepped portion formed to the opening of the valve chamber in the valve body, and the sealing member is inserted to the stepped portion and fixed to position via the crimping portion. 
   Moreover, the sealing member can be equipped with a tapered surface that is pressed against the stepped portion of the valve chamber, or with a seal fit to an outer circumference thereof. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of an expansion valve according to the present invention; 
       FIG. 2  is an enlarged view of the relevant portion of  FIG. 1 ; 
       FIG. 3  is an explanatory view showing another embodiment of the present invention; and 
       FIG. 4  is an explanatory view showing yet another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is a cross-sectional view showing an expansion valve according to the present invention. 
   The expansion valve, the whole of which being denoted by a reference number  10 , has a rectangular column shaped valve body  30  made of an aluminum alloy, which includes a passage  32  for the refrigerant flowing in from the receiver toward the evaporator. Passage  32  communicates via a valve chamber  35  and an orifice  32   a  to an outlet port  321  opening toward the evaporator. 
   A spherical valve means  32   b  is supported on a supporting member  32   c  inside the valve chamber  35 . A sealing member  150  is inserted to an opening  35   a  of the valve chamber  35 , and a coil spring  32   d  is disposed between the sealing member  150  and the supporting member  32   c  of the valve means  32   b  fixed to position by a crimping portion K 1  providing fixing via crimping, the coil spring biasing the valve means  32   b  toward the orifice  32   a.    
   The refrigerant returning from the evaporator is sent toward the compressor through a passage  34 . 
   A power element portion  36  for actuating the valve means is attached to the upper portion of the valve body  30 . 
   The power element portion  36  has an upper cover  36   d  and a lower cover  36   h , between which a diaphragm  36   a  is sandwiched. An upper pressure actuated chamber  36   b  is formed between the diaphragm  36   a  and the upper cover  36   d , which is filled by an actuating gas through a tube  36   i.    
   The lower surface of the diaphragm  36   a  is supported by a stopper member  312 . The stopper member  312  has a large diameter portion  314  and a small diameter portion  315 , between which a lower pressure actuated chamber  36   c  is formed. 
   The lower cover portion  36   h  is fixed to the valve body  30  through a screw thread portion  361 . 
   The lower pressure actuated chamber  36   c  is communicated with passage  34  via an opening  36   e.    
   The actuating rod  316  inserted to the small diameter portion  315  of the stopper member  312  also functions as a heat sensing rod for transmitting the refrigerant temperature via the stopper member  312  to the upper pressure actuated chamber  36   b.    
   The actuating rod  316  is passed through the center of the valve body  30  and actuates the valve means  32   b . A seal member  50  attached to the actuating rod  316  is inserted to a bore  38  that communicates with passage  34 . 
   A snap ring  41 ′ is used to restrict movement. 
   This sealing mechanism enables the refrigerant traveling toward the evaporator and the refrigerant returning from the evaporator to be separated completely. 
   The expansion valve  10  of the present invention is composed as described above, and by the operation of the power element portion  36 , the opening of the refrigerant passage between the valve means  32   b  and the orifice  32   a  is controlled so as to control the flow of refrigerant. 
     FIG. 2  is an enlarged view showing the structure for attaching the sealing member  150  to the valve chamber  35  of  FIG. 1 . 
   The sealing member  150  has a flat surface. An opening  35   a  of the valve chamber  35  formed to the valve body  30  has a stepped portion  35   x  formed between the valve chamber  35 . By pushing the sealing member  150  into the opening  35   a  via the crimping portion K 1 , a tight seal is formed with the stepped portion. 
     FIG. 3  is an explanatory view showing another embodiment of the present invention. 
   A sealing member  250  has a tapered surface  35   y  formed to the upper surface thereof. An opening  35   a  of the valve chamber  35  formed to the valve body  30  has the stepped portion  35   x  formed between the valve chamber  35 . By pushing the sealing member  250  into the opening  35   a  via the crimping portion K 1 , a tight seal S 1  is formed with the stepped portion  35   x.    
     FIG. 4  is an explanatory view showing yet another embodiment of the present invention. 
   A sealing member  350  has a seal  360  mounted to the outer circumference thereof. The sealing member  350  is fit to the opening  35   a  of the valve chamber  35  via the crimping portion K 1 . The sealing member  350  includes a circumferential groove  350   x  formed radially into a circumferential surface  350   y  of the sealing member  350 . The seal  360  is sized to be received by the circumferential groove  350   x  in a close-fitting manner such that, when the sealing member  350  with the seal  360  received by the circumferential groove  350   x  is fixed to the valve body  30 , the seal  360  contacts a circumferential inner wall surface  35   x  of the valve chamber  35 . An even more reliable seal is achieved by providing the seal  360 .