Abstract:
An expansion valve  1  comprises a square-column-shaped valve body  10 , and a spherical valve means  30  housed within a valve chamber  20  opposing against a valve seat  22 . A working shaft  50  coming into contact with said valves means  30  connects to a stopper member  60 , thereby transmitting to the valve means  30  the movement of a diaphragm  230  being displaced by the pressure change in a pressure chamber  240  of a power element  200 . A lower housing  220  of the power element  200  is provided with an opening portion and claws, which enable the power element to be coupled to a mounting unit  100  formed to the top portion of the valve body  10 . An elastic packing member  150  enables the element to be securely and airtightly coupled to the body. According to the present invention, the assembling of the valve is simplified and the manufacturing cost is reduced.

Description:
FIELD OF THE INVENTION 
   The present invention relates to an expansion valve for a refrigerant used in a refrigeration cycle of an air conditioner or a refrigeration device and the like. 
   DESCRIPTION OF THE RELATED ART 
   The conventional expansion valve of the present type is disclosed for example in Japanese Patent Laid-Open Provisional Publication No. 2000-97522 filed by the present applicant, wherein a member called a power element that stores a pressure chamber filled with working gas is coupled to a valve body made of aluminum alloy etc., the displacement of the diaphragm operated by the pressure of the working gas filled inside the pressure chamber being transmitted to a valve means thereby controlling the flow of the refrigerant. 
   In the above-mentioned type of expansion valves, a screw mechanism is used for coupling the power element and the valve body. 
   However, according to the screw mechanism, it is necessary to provide screw threads to both members being coupled, and upon coupling the two members, the power element must be rotated until it reaches the end of the screw thread in order to complete the coupling process. At the same time, measures for preventing refrigerant gas from leaking must be provided to the screw coupling portion. 
   SUMMARY OF THE INVENTION 
   Therefore, the present invention aims at providing an expansion valve that enables the power element to be coupled to the valve body by a simple operation. 
   The expansion valve according to the present invention comprises a first passage through which refrigerant traveling from a compressor toward an evaporator travels, a second passage through which refrigerant returning from the evaporator toward the compressor travels, a valve body including a valve chamber formed in the middle of the first passage and housing a valve means, and a power element having a driving function for operating the valve means, wherein a coupling means for coupling the valve body and the power element comprises a cylindrical portion mounted to the top portion of the valve body, plural projections protruding from the cylindrical portion toward the outer circumferential direction, and plural claws formed to the housing of the power element designed to engage with the projections formed to the valve body. 
   Further, the coupling means for coupling the valve body and the power element comprises a ring-shaped groove formed to the top portion of the valve body, plural projections protruding from the ring-shaped groove toward the inner circumferential direction, and plural claws formed to the housing of the power element designed to engage with the projections formed to the valve body. 
   The coupling means for coupling the valve body and the power element is equipped with two projections and two claws which are disposed at 180 degree intervals. 
   According to another example, the coupling means for coupling the valve body and the power element can be equipped with three projections and three claws which are disposed at 120 degree intervals, or with four projections and four claws which are disposed at 90 degree intervals. 
   Furthermore, the expansion valve comprises a packing member formed of an elastic material, which is mounted to the top portion of the valve body and pressed by the power element. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a cross-sectional view of the expansion valve according to the present invention; 
       FIG. 2  is a cross-sectional view showing the structure of the power element; 
       FIG. 3  is a plan view showing the structure of the power element; 
       FIG. 4  is a plan view showing the structure of the power element; 
       FIG. 5  is a cross-sectional view showing the upper portion of the expansion valve body; 
       FIG. 6  is an explanatory view showing the structure of the coupling means; 
       FIG. 7  is an explanatory view showing the structure of the coupling means; 
       FIG. 8  is an explanatory view showing the structure of the coupling means; 
       FIG. 9  is a cross-sectional view showing another example of the expansion valve according to the present invention; and 
       FIG. 10  is across-sectional view showing yet another example of the expansion valve according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  is a cross-sectional view showing one preferred embodiment of the expansion valve according to the present invention. 
   An expansion valve denoted as a whole by reference number  1  comprises a square column shaped valve body  10  formed for example of aluminum alloy. 
   The valve body  10  includes first passages  11  and  12  through which passes the refrigerant traveling from a condenser and a receiver toward an evaporator constituting the refrigerant cycle not shown, with a valve chamber  20  formed in the middle of the first passages  11 ,  12 . The valve chamber  20  is equipped with a valve seat constituting an orifice  22  that communicates the passage  11  with passage  12 , and a spherical valve means  30  is supported by a valve member  32  so as to oppose to the valve seat. The valve means  32  is supported via a pressure spring  34  by a pressure regulating screw  36 , and by adjusting the screwing of the pressure regulating screw  36  toward the valve chamber  20 , the pressing force of the valve means  30  toward the orifice is regulated. 
   The valve body  10  is provided with a second passage  26  through which refrigerant flowing from an evaporator to a compressor not shown travels. 
   An opening  28  is formed along the longitudinal axis of the valve body  10  orthogonal to the second passage  26 , and the circumference of the opening  28  on the upper surface  110  on the top of valve body  10  is formed amounting portion  100  for mounting a power element  200 . 
   The power element  200  comprises an upper housing  210  and a lower housing  220 , which are welded together at their periphery to create an integral housing structure, and a diaphragm  230  sandwiched between the upper and lower housings. 
   A pressure chamber  240  is defined between the diaphragm  230  and the upper housing  210 , which is filled with working gas and sealed with a plug  242 . 
   A stopper member  60  is disposed between the diaphragm  230  and the lower housing  220 , and the stopper member  60  transmits the displacement of the diaphragm  230  to the valve means  30  through a working rod  50 . 
   A seal ring  52  is mounted via a snap ring  54  to the outer side of the working rod  50  in the valve body  10 , thereby sealing the refrigerant. 
   According to the present expansion valve, the power element  200  can be assembled to the mounting portion  100  of the valve body  10  through a simple mounting operation. 
     FIG. 2  is a cross-sectional view of the lower housing  220 ,  FIG. 3  is a plan view thereof,  FIG. 4  is a plan view of the valve body, and  FIG. 5  is a cross-sectional view thereof. 
   The lower housing  220  comprises a joint portion  221  to be bonded to the upper housing  210 , and a flat portion  222 , with an opening  224  formed to the center area thereof. A plurality of claws  226  extending toward the center of the opening  224  is formed to the inner circumference of the flat portion  222 . 
   On the other hand, a mounting portion  100  that protrudes from the upper surface  110  of the valve body is provided to the top portion of the valve body  10 . 
   The mounting portion  100  includes a cylindrical portion  104  and plural projections  102  that protrude outward from the cylindrical portion  104 . Spaces  106  are formed between the neighboring projections  102  through which the claws  226  of the lower housing  220  of the power element  200  can pass. 
   On the upper surface  110  of the valve body is created a ring-shaped packing groove  120 , to which is inserted a ring-shaped packing member  150 . 
   The packing member  150  is made of an elastic material and designed to protrude above the upper surface  110  of the valve body when in a free condition. 
   When assembling the power element  200  to the valve body  10 , a power element  200  is assembled and completed at first, having the diaphragm  230  and the stopper member  60  equipped to the interior thereof and filled with working gas. Then, the lower housing  220  is positioned so as to come into contact with the upper surface  110  of the valve body so that the claws  226  of the lower housing  220  of the power element  200  pass through the spaces  106  formed to the mounting portion  100  of the valve body  10 . Then, while compressing the packing member  150 , the power element  200  is twisted around the axis. Through this movement, the claws  226  of the power element come into contact with the lower surface of the projections  102  at the mounting portion  100  of the valve body. By releasing the force pressing the power element  200 , the claws  226  are pressed against the projections  102  by the elasticity of the packing member  150 , and the power element  200  is thereby securely fixed to the mounting portion  100  of the valve body. 
   According to the present expansion valve, the power element can be mounted to the valve body by a simple operation. Therefore, the number of steps required to assemble the power element to the valve body can be minimized. 
     FIG. 6  shows another mounting structure of the expansion valve according to the present invention, wherein (a) is a planar structure of the power element, and (b) is the planar structure of the valve body. 
   The lower housing of the power element comprises a flat portion  222   a  and an opening  224   a , the opening  224   a  formed to the center area of the flat portion  222   a . Further, two claws  226   a  that protrude toward the opening  224   a  are formed thereto which are spaced apart by 180 degrees. Moreover, the angle that the side edges of each fan-shaped claw  226   a  create is, for example, approximately 60 degrees. 
   On the other hand, the mounting portion  100   a  formed to the upper surface  110  of the valve body comprises a cylindrical portion  104   a  and two projections  102   a  that protrude outward therefrom. Spaces  106   a  are created between the two projections  102   a.    
   Upon mounting the power element to the valve body, the power element is inserted to the upper surface  110  of the valve body in the position where the claws  226   a  on the lower housing of the power element do not interfere with the projections  102   a  on the mounting portion of the valve body. Thereafter, the power element is rotated until the claws  226   a  of the power element come into contact with the back surface of the projections  102   a  of the valve body. 
   The structure for fitting the packing member to the groove  120  formed to the upper surface  110  of the valve body is similar to the first embodiment. 
     FIG. 7  shows yet another example of the mounting mechanism. 
   The lower housing of the power element comprises a flat portion  222   b  and an opening  224   b , the opening  224   b  provided to the center area of the flat portion  222   b , further comprising two fan-shaped claws  226   b  formed to protrude toward the opening  224   b . The angle of opening of the claws  226   b  is, for example, approximately 90 degrees. 
   A mounting portion  100   b  is equipped to the upper surface  110  of the valve body. The mounting portion  100   b  comprises a cylindrical portion  104   b  and two projections  102   b  that protrude outward from the cylindrical portion  104   b.    
   Upon mounting the power element to the valve body, the claws  226   b  on the power element are inserted through the spaces  106   b  formed to the valve body, and the power element is rotate until the claws  226   b  come into contact with the projections  102   b.    
     FIG. 8  shows yet another example of the mounting mechanism. 
   The lower housing of the power element comprises a flat portion  222   c  and an opening  224   c , the opening  224   c  formed to the center of the flat portion  222   c , with three claws  226   c  that are disposed at 120 degree intervals. The angle of opening of each fan-shaped claw  226   c  is, for example, approximately 60 degrees. 
   A mounting portion  100   c  is provided to the upper surface  110  of the valve body. The mounting portion  100   c  includes a cylindrical portion  104   c  and three projections  102   c  that protrude from the outer periphery of the cylindrical portion. 
   Upon mounting the power element to the valve body, the claws  226   c  on the power element is inserted through the spaces  106   c  on the valve body, and the power element is rotated until the claws  226   c  come into contact with the projections  102   c.    
   All the above-mentioned examples include a packing member inserted to the groove  120  on the upper surface  110  of the valve body. 
     FIG. 9  is a cross-sectional view showing another embodiment of the present invention. 
   The structure of the expansion valve is similar to the one explained previously, so the components are provided with the same reference numbers and detailed descriptions thereof are omitted. 
   The structure of the mounting unit  100  provided to the top of the valve body  10  is also similar to the one explained previously. 
   The power element  300  comprises an upper housing  310 , a lower housing  320 , and a diaphragm  330  that defines a pressure chamber  340 . A working gas is filled in the pressure chamber  340 , which is sealed by a plug  342 . 
   The lower housing  320  comprises two step portions, and is connected to the mounting unit of the valve body. The mounting mechanism is the same as those explained previously. In the present example, the thickness of the stopper member  60   a  is increased to correspond to the size of the lower housing  320 . 
     FIG. 10  is a cross-sectional view showing yet another embodiment of the present invention. 
   The structure of the expansion valve is the same as the ones explained previously, so the same components are provided with the same reference numbers and detailed descriptions thereof are omitted. 
   The structure of the mounting unit  170  equipped to the top of the valve body  10  comprises a ring-shaped groove having a slit formed along the axial direction of the valve body. 
   The power element  400  comprises an upper housing  410 , a lower housing  420 , and a diaphragm  430  that defines a pressure chamber  440 . The pressure chamber  440  is filled with working gas and sealed by a plug  442 . 
   A collar  422  spreading outward is formed to the end of the lower housing  420 , which is inserted to the slit formed to the valve body  10 , and the power element  400  is connected to the valve body  10  by rotating the element  400 . The shape of the collar  422  and the mounting groove  170  of the valve body are similar to those explained previously. 
   As explained, the present invention enables the power element to be assembled to the expansion valve body by a simple operation, so the manufacturing procedure of the expansion valve is effectively simplified. 
   Even further, the present invention provides a secure sealing structure for sealing the refrigerant gas.