Patent Publication Number: US-2019178542-A1

Title: Expansion valve

Description:
TECHNICAL FIELD 
     The present invention relates to an expansion valve having a built-in temperature sensitive mechanism for use in a refrigerating cycle. 
     BACKGROUND ART 
     Typically, thermal expansion valves having built-in temperature sensitive mechanisms capable of adjusting the amount of passing refrigerant based on temperature are used in the refrigerating cycles of air conditioners provided in automobiles and the like. A valve body of this type of expansion valve includes an inlet port through which a high-pressure refrigerant is introduced, a valve chamber that communicates with the inlet port, and a valve element driving mechanism referred to as a power element disposed on a top portion of the valve body. 
     A spherical valve element disposed in the valve chamber is arranged opposing a valve seat of a valve hole formed in the valve chamber. The valve element is supported by a support member disposed in the valve chamber, and the valve element is pushed toward a direction of the valve seat by a coil spring disposed between an adjusting screw mounted to the valve body and the support member. The valve element is operated by a valve rod that is driven by a power element, and controls an opening of a throttle passage formed between the valve element and the valve seat. The refrigerant that passes through the valve hole is sent from an outlet port toward an evaporator. 
     Here, although the high-pressure refrigerant flowing from the inlet port passes through the valve chamber, there are also cases where pressure fluctuation may occur in the high-pressure refrigerant sent to the expansion valve on the upstream side in the refrigerant cycle, and if the pressure fluctuation is transmitted, a problem may occur in that operation of the valve element becomes unstable. Such pressure fluctuation may cause vibration of the valve element, which leads to the occurrence of abnormal noise. 
     In order to prevent such vibration, configurations have been proposed in the related art in which a vibration isolation spring is provided in the valve chamber to elastically support the valve element (see Patent Literatures 1 and 2). 
     CITATION LIST 
     Patent Literature 
     [PTL 1] Japanese Patent Application Laid-Open Publication No. 2005-156046 
     [PTL 2] Japanese Patent Application Laid-Open Publication No. 2013-68368 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     Although the configuration of the vibration isolation springs in the related art exerts a vibration isolation effect to some degree, it is associated with the following problems. 
     Patent Literature 1 discloses a configuration in which a vibration isolation spring having a plurality of elastic arms, or leg portions, is provided on a support member that supports a valve element, wherein leading ends of the respective leg portions are caused to be in contact elastically with an inner wall of the valve chamber such that the support member is stably supported from a circumference of the support member toward a center thereof. 
     However, since Patent Literature 1 utilizes a configuration in which the leg portions of the vibration isolation spring directly collide with the refrigerant flowing into the valve chamber through the inlet port, there is the concern that turbulence may occur in the high-pressure refrigerant introduced into the valve chamber. This problem will be described with reference to  FIGS. 7 to 10 . 
     As illustrated in  FIG. 7 , high-pressure refrigerant sent out from a compressor (not shown) enters an inlet port  320 , as illustrated by arrow A, passes through an inlet hole  320   a,  and is introduced to a valve chamber  324 . Here, the vibration isolation spring  300  of the related art is composed of an annular plate-shaped portion  301  sandwiched between a support member  400  of the valve element and a coil spring  344  that pushes the support member  400  toward the valve element, and a plurality of leg portions  302  that extend radially from the plate-shaped portion  301  and bend such that they are inclined with respect to a center axis direction of the valve rod. The plurality of leg portions  302  extend to a lower side wall  324   b  of the valve chamber  324 , which is lower than the inlet hole  320   a.  Here, depending on the angle (the angle of rotation around the center point of the vibration isolation spring  300 ) at which the vibration isolation spring  300  is attached, the leg portions  302  form various flow path shapes with respect to the inlet hole  320   a.    
       FIGS. 8 to 10  illustrate examples of the shapes of inlet flow paths formed by the inlet hole  320   a  and a leg portion  302  as viewed from the inlet port  320  side.  FIG. 8  illustrates a case where the leg portion  302  is positioned vertically at the center of the inlet hole  320   a  such that an opposing flow path is divided into two branches.  FIG. 9  illustrates a case where the leg portion  302  is blocking one side of the inlet hole  320   a.    FIG. 10  illustrates a case where leg portions  302  are positioned at both sides of the inlet hole  320   a,  forming a gate-type flow path. Since the leg portions  302  block a portion of the inlet hole  320   a  in the various ways described above, and the shape of the inlet flow path changes accordingly, turbulence may be caused depending on the direction of the vibration isolation spring  300 . Such turbulence may cause generation of refrigerant passing noise, and there is the concern that abnormal noise may be generated, by the bursting of bubbles, for example. Further, there is a concern that the flow rate of the introduced refrigerant may decrease. 
     In contrast, Patent Literature 2 discloses a technique of shortening the length of the leg portions in the central axis direction by bending the leg portions of a vibration isolation spring in a radial direction around a center axis of a valve rod. In this case, however, unless the vibration isolation spring is twisted when being inserted into the valve body, a load is applied, especially to the base portion of the leg portions, and there is also a concern that deformation of the vibration isolation spring may occur. 
     Accordingly, an object of the present invention is to provide an expansion valve including a vibration isolation spring that suppresses vibration of a valve body and suppresses deformation of the vibration isolation spring to reduce refrigerant passing noise. 
     Solution to Problem 
     In order to solve the problems described above, one typical example of an example valve according to the present invention includes a valve body comprising an inlet hole through which a refrigerant flows into a valve chamber, and a valve hole through which the refrigerant flows out from the valve chamber; a valve element configured to adjust an amount of the refrigerant flowing through the valve hole; a power element that is mounted to the valve body and configured to drive the valve element through a valve rod; a support member configured to support the valve element; a coil spring configured to press the valve element in a valve-closing direction through the support member; and a vibration isolation spring configured to prevent vibration of the valve element, wherein the vibration isolation spring includes an annular base portion disposed between the support member and the coil spring, and a plurality of leg portions that extend radially from the base portion, and wherein the leg portions are bent toward the coil spring and are in contact with a side wall surface of the valve chamber on a valve hole side of the inlet hole. 
     According to an embodiment of the expansion valve according to the present invention, the plurality of leg portions may include connecting portions of leg portions that are adjacent in a same plane as the base portion. 
     Advantageous Effects of Invention 
     As the expansion valve according to the present invention is configured as described above, it is possible to suppress the vibration of the valve element and to suppress the deformation of the vibration isolation spring to reduce the refrigerant passing noise. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a vertical cross-sectional view illustrating a first embodiment of an expansion valve according to the present invention. 
         FIG. 2  is a vertical cross-sectional view of a main portion of the expansion valve according to the first embodiment. 
         FIG. 3  is a perspective view illustrating a vibration isolation spring according to the first embodiment. 
         FIG. 4  is a plan view illustrating the vibration isolation spring according to the first embodiment. 
         FIG. 5  is a side view illustrating the vibration isolation spring according to the first embodiment. 
         FIG. 6  is a plan view illustrating the vibration isolation spring according to a second embodiment. 
         FIG. 7  is a vertical cross-sectional view illustrating one example of an expansion valve of the related art. 
         FIG. 8  is a view illustrating an example of a shape of an inlet flow path according to the expansion valve of the related art. 
         FIG. 9  is a view illustrating an example of a shape of the inlet flow path according to the expansion valve of the related art. 
         FIG. 10  is a view illustrating an example of a shape of the inlet flow path according to the expansion valve of the related art. 
     
    
    
     Description of Embodiments 
     First Embodiment 
       FIG. 1  is a vertical cross-sectional view illustrating a first embodiment of an expansion valve according to the present invention.  FIG. 2  is a vertical cross-sectional view of a relevant portion of an expansion valve according to a first embodiment. 
     As illustrated in  FIG. 1 , the expansion valve  10  includes a valve body  11 , a power element  70 , a valve element  40 , a valve rod  60 , an O ring  36 , a support member  100 , a vibration isolation spring  140 , a coil spring  44  and an adjusting screw  120 . 
     The valve body  11  is made of an aluminum alloy, for example, and can be obtained by subjecting an aluminum alloy or the like to extrusion molding with the X direction of  FIG. 1  set as the extrusion direction, and then performing machining. The valve body  11  includes a power element mounting portion  12 , which is an internal screw formed on an upper surface portion and engaged with an external screw  72   a  of the power element  70  to thereby fix the power element  70 , an inlet port  20  through which a high-pressure refrigerant is introduced, a refrigerant outlet port  28  through which the refrigerant flowing in from the inlet port  20  flows out, a return passage  30  for the refrigerant, a hole portion  33  to which the O ring  36  is attached, an internal screw  11   a  formed on a bottom side portion of the valve body  11 , and a mounting hole (or an internal screw for mounting)  80  for mounting the valve body  11  to an evaporator or other components not shown. 
     The power element mounting portion  12  is formed as a bottomed cylindrical hole having a circular opening on an upper surface of the valve body  11  and having an internal screw formed on an inner wall surface thereof. An opening  32  that reaches (communicates with) the return passage  30  is formed at the center of the bottom portion of the hole. Here, the direction of the center axis of the power element mounting portion  12  is a direction (the Y direction) that is substantially orthogonal to the passing direction (the X direction) of the refrigerant passing through the inside of the return passage  30 . 
     The internal screw  11   a  is formed so as to open on the lower side of the valve body  11 , and an insertion hole  11   b  is formed on an upper portion thereof. By sealing an opening of the internal screw  11   a  with the adjusting screw  120 , a valve chamber  24  is formed in the inner side of the valve body  11 . The valve chamber  24  has a cylindrical side wall surface, and the surface above the upper end of the inlet hole  20   a  is referred to as an upper wall surface  24   a,  and the surface below the lower end of the inlet hole  20   a  is referred to as a lower wall surface  24   b.  The vertical length of the upper wall surface  24   a  is sufficient to enable the vibration isolation spring  140  described later to move in a sliding motion. In addition, it is sufficient for the area between the upper end of the insertion hole  11   b  and the inlet hole  20   a  to have a thickness capable of ensuring the necessary strength. 
     The inlet port  20  is formed to communicate with the valve chamber  24  from the side of the valve chamber  24  via an inlet hole  20   a  having a smaller diameter than the inlet port  20 . In addition, a narrow portion  28   a  having a smaller diameter than the outlet port  28  is provided behind the outlet port  28 , and the narrow portion  28   a  is disposed above the valve chamber  24 . The narrow portion  28   a  communicates with an upper end portion of the valve chamber  24  via a valve hole  26  that serves as an orifice. A valve seat  25  is formed on the valve chamber  24  side of the valve hole  26 . A through hole  29  is formed vertically (the Y direction of  FIG. 1 ) in the valve body  11  so as to communicate the return passage  30  with the narrow portion  28   a.  The valve hole  26 , the through hole  29 , the opening  32  and the valve chamber  24  are disposed so that their respective center axes are aligned in a straight line. The return passage  30  is formed further above the outlet port  28  in the valve body  11 , and passes through the valve body  11  in a lateral direction (the X direction of  FIG. 1 ). Further, a hole portion  33  that is coaxial with the through hole  29  and having a greater inner diameter than the through hole  29  is formed on a lower side of the return passage  30 . 
     It should be noted that, in  FIG. 1 , although the inlet port  20  and the outlet port  28  are opened on the right and left sides of the valve body  11 , and similarly, the return passage  30  is formed to pass through the right and left sides of the valve body  11 , the arrangement of the inlet port, the outlet port and both openings of the return passage can be changed arbitrarily depending on the layout of the refrigerant cycle in which the expansion valve is disposed. For example, the outlet port  28  and the left side opening of the return passage  30  may be disposed to be opened to the front side or the back side of the drawing of  FIG. 1 , that is, the inlet port and the outlet port may be arranged orthogonally when viewed from the center line of the valve rod  60 , and similarly, both openings of the return passage may be arranged orthogonally. 
     The power element  70  is composed of an upper lid member  71  and a receiving member  72  having a through port  72   b  formed at a center portion thereof, both of which are formed of stainless steel or the like, for example, a diaphragm  73  sandwiched between the upper lid member  71  and the receiving member  72 , and a stopper member  90  disposed between the diaphragm  73  and the receiving member  72 . By circumferentially welding the edge portions where the upper lid member  71 , the diaphragm  73  and the receiving member  72  overlap, these members are integrated. A pressure operation chamber  75  is formed between the upper lid member  71  and the diaphragm  73 , and after filling the pressure operation chamber  75  with a working gas, the chamber is sealed with a sealing plug  65 . The lower portion of the receiving member  72  is cylindrical, and an external screw  72   a  is formed on the periphery thereof. The power element  70  is attached to the valve body  11  by screwing the external screw  72   a  into the internal screw (the internal screw opening on the upper surface of the valve body  11 ) of the power element mounting portion  12  via the packing  35 . 
     The valve element  40  is a spherical member that is disposed in the valve chamber  24  at a position opposed to the valve seat  25 . The valve rod  60  is provided to pass through the valve hole  26 , the through hole  29  and the opening  32  of the valve body  11 , wherein an upper end of the valve rod  60  is abutted against a receiving portion  92  provided on a lower side of the stopper member  90  of the power element  70  and a lower end of the valve rod  60  is disposed to contact the valve element  40 . The O ring  36  is arranged in the hole portion  33 , and a stopper member  37  attached to an upper portion thereof serves as a stopper to retain the O ring  36 . 
     The support member  100  is a member that supports the valve element  40  in the direction of the valve seat  25  (the direction of the valve rod  60 ). Although the valve element  40  is fixed to the support member  100 , since the support member  100  is constantly pushed toward the direction of the valve seat  25  and the valve rod  60  by the coil spring  44 , a configuration in which the support member  100  merely contacts the valve element  40  may be utilized. The support member  100  includes a body portion  103 , an upper surface portion  101  and a flange portion  102 . The upper surface of the cylindrical body portion  103  has a conical recess and serves as the upper surface portion  101  that supports a lower surface of the valve element  40 . In addition, the support member  100  includes a flange portion  102  that protrudes toward a lateral side (to the outer circumferential side) from the body portion  103 , and a lower surface of the flange portion  102  is configured to receive one end of the vibration isolation spring  140  and the coil spring  44 . In this state, the outer diameter of the body portion  103  below the flange portion  102  is configured to be smaller than an inner diameter of the coil spring  44 , such that the body portion  103  fits inside the coil spring  44 . 
     The coil spring  44  is disposed between a lower surface of the flange portion  102  provided on the support member  100  and a concave portion  125  formed in the adjusting screw  120 . Due to the elastic force of the coil spring  44 , the valve element  40  is pushed toward the valve seat  25  via the support member  100 . The vibration isolation spring  140  is disposed between the lower surface of the flange portion  102  and the coil spring  44 , the detailed configuration of which will be described later. 
     The adjusting screw  120  includes a body portion  121 , a hexagonal socket  122 , an insertion portion  123 , a leading edge portion  124 , and the concave portion  125 . The insertion portion  123  is formed above the body portion  121  with a smaller outer diameter than the body portion  121 , and the leading edge portion  124  is formed above the insertion portion  123  with a smaller outer diameter than the insertion portion  123 . In addition, the outer circumference of the body portion  121  is formed to be an external screw portion  121   a  designed to engage with the internal screw  11   a  formed on a lower side of the valve body  11 . Further, a concave portion  125  having a cylindrical space with the upper portion opened is provided on an upper portion of the adjusting screw  120 . The concave portion  125  is formed to have a depth that reaches the vicinity of the body portion  121 . In addition, the inner diameter of the concave portion  125  is designed to be slightly greater than the outer diameter of the coil spring  44 , such that the coil spring  44  is stably disposed within the concave portion  125 . Furthermore, the hexagonal socket  122  that allows insertion of a hexagonal wrench (not shown) for turning the adjusting screw  120  is disposed at a lower portion of the adjusting screw  120  (the body portion  121 ). 
       FIG. 3  is a perspective view illustrating the vibration isolation spring  140  according to a first embodiment.  FIG. 4  is a plan view illustrating the vibration isolation spring  140  according to the first embodiment.  FIG. 5  is a side view illustrating the vibration isolation spring according to the first embodiment. The vibration isolation spring  140  includes a base portion  141  and a leg portion  142 . The vibration isolation spring  140  can be formed by press-forming a plate member having elasticity, such as stainless steel or an alloy thereof, for example. 
     The base portion  141  is an annular plate-like member that forms an upper portion of the vibration isolation spring  140  and includes a mounting hole  141   a  formed at the center thereof. 
     A plurality of the leg portions  142  extend from an outer circumferential side of the base portion  141  in a direction perpendicular with respect to a tangent in the circumferential direction; that is to say, radially. In the first embodiment, eight leg portions  142  having the same lengths are provided at regular angular intervals. Each leg portion  142  is composed of an upper portion  142   a,  a bent portion  142   b,  a side portion  142   c,  and a projected portion  142   d.  The leg portions  142  are bent downward at the bent portion  142   b.    
     The upper portion  142   a  is formed substantially on the same plane as the base portion  141 . Therefore, in the base portion of each of the leg portions  142 , a cutout  145  having a predetermined shape is formed respectively on the side having the base portion  141 . In  FIG. 4 , length C refers to the length of the upper portion  142   a.  Since the leg portions  142  include the upper portions  142   a , the leg portions  142  are formed closer to a center side of the base portion  141  than the bent portions on the same plane as the base portion  141 . In addition, in the vicinity of the connecting portion of the upper portion  142   a  and the base portion  141  (near the base end of the leg portions  142 ), the cutouts  145  formed between the side surfaces in the width direction of adjacent upper portions  142   a  are formed in an arc shape by continuously connecting base sides of the upper portions  142   a  with the same curvature, and as a result, the upper portions  142   a  (the leg portions  142 ) are smoothly connected to each other. Of course, the cutouts  145  may also be formed in a shape other than an arc shape by connecting the base sides of the upper portions  142   a  with a different curvature. 
     The bent portion  142   b  is formed continuously bending outward from the upper portion  142   a  toward the lower side (toward the coil spring  44 ). The bent portion  142   b  may be formed with a fixed curvature radius. The bent portion  142   b  is formed by bending the portion with a (90−θ) degree bending process. 
     The side portion  142   c  is formed in a straight line that extends continuously downward from the bent portion  142   b.  The angle of the side portion  142   c  is θdegrees toward the outer downward direction with respect to the vertical direction. 
     The projected portion  142   d  is formed outward in the vicinity of the lower end of the side portion  142   c.  For example, the projected portion  142   d  may be formed as a part of a spherical surface, such as a hemispherical shape. When the projected portion  142   d  is mounted on the valve body  11 , although the projected portion  142   d  elastically contacts a portion above the opening portion of the inlet hole  20   a  (the upper wall surface  24   a ), the dimensions of the respective portions are designed such that the projected portion  142   d  is not inserted into the opening of the inlet hole  20   a  even if the valve element  40  is positioned at a lowermost position. 
     Although the vertical length of the leg portions  142  may be set to an arbitrary length as long as the lower edge portions of the leg portions  142  do not fall into the opening portion of the inlet hole  20   a  at the lowermost end of the vertical movement of the vibration isolation spring  140 , in order to prevent interference of the flow of refrigerant introduced from the inlet port  20 , it is preferable that the lower edge portion of the leg portions  142  does not reach the opening of the inlet hole  20   a.  In addition, according to the present embodiment, although the widths of the respective leg portions  142  are formed to be constant in each of the upper portion  142   a,  the bent portion  142   b  and the side portion  142   c,  the present invention is not restricted to this example, and narrowing or widening the width at the leading ends or other design modifications for most effectively suppressing the vibration of the valve element may be utilized. In addition, the thickness of the leg portion  142  (the thickness of the vibration isolation spring  140  in the case that the vibration isolation spring  140  is formed by press-forming a single elastic plate material) may be configured to a thickness that is suitable for suppressing the vibration of the valve element. 
     In the vibration isolation spring  140 , a gap D ( FIG. 4 ) through which the refrigerant passes is formed between the respective adjacent leg portions  142 . In addition, the outer diameter connected by the leading edge portions of the projected portion  142   d  of the vibration isolation spring  140  is formed to be greater than the inner diameter of the upper wall surface  24   a  within the valve chamber  24 , such that an elastic force acts when the vibration isolation spring  140  is mounted, and the projected portions  142   d  are pressed against the upper wall surface  24   a  of the valve chamber  24 . In addition, a space large enough for the coil spring  44  to be disposed therein is secured on the inner side of the leg portions  142 . 
     As illustrated in  FIGS. 1 and 2 , when attaching the vibration isolation spring  140 , first, the vibration isolation spring  140  is passed through the mounting hole  141   a  from the lower side to the body portion  103  of the support member  100 , and the upper surface of the base portion  141  of the vibration isolation spring  140  is brought into contact with the lower surface of the flange portion  102  of the support member  100 . Next, the coil spring  44  is attached from the lower side of the vibration isolation spring  140 . In this state, the body portion  103  of the support member  100  is disposed on an inner side of the coil spring  44 , and the upper surface of the coil spring  44  abuts against the lower surface of the base portion  141  of the vibration isolation spring  140 . In this way, the vibration isolation spring  140  is disposed inside the valve chamber  24 . 
     In the expansion valve  10  to which the vibration isolation spring  140  is attached, since the base portion  141  of the vibration isolation spring  140  is pushed by the coil spring  44  from the lower side, the vibration isolation spring  140  is attached by being sandwiched between the flange portion  102  of the support member  100  and the coil spring  44  with a predetermined force. Then, in the vibration isolation spring  140 , the projected portions  142   d  are pushed toward the upper wall surface  24   a  of the valve chamber  24  with a predetermined force due to the elastic force of the leg portions  142 , and a sliding resistance is generated in accordance with the movement of the valve element  40 . 
     Next, the operation of the expansion valve will be described. In the expansion valve  10  of the first embodiment according to the present invention, a high-pressure refrigerant discharged from a compressor (not shown) flows from the inlet port  20  through the inlet hole  20   a  into the valve chamber  24 , passes through the valve hole  26  and expands, and is subsequently sent out through the outlet port  28  to an evaporator (not shown). The refrigerant sent out from the evaporator enters from the left side entrance of the return passage  30 , passes through the return passage  30  to exit from the right side exit, and returns to the compressor. At this time, a portion of the refrigerant passing through the return passage  30  flows through the opening  32  to a lower portion of the power element  70 . Then, the temperature change of the refrigerant that flows to the lower portion of the power element  70  causes the pressure of the working gas inside the pressure operation chamber  75  to change accordingly. At this time, the stopper member  90  moves up and down in response to the movement of the diaphragm  73  that deformed according to the fluctuation of the internal pressure of the pressure operation chamber  75 . The movement of the stopper member  90  is transmitted through the valve rod  60  to the valve element  40 , and the flow rate of the expanded refrigerant is controlled. 
     In the case that the valve element  40  moves in an opening and closing direction (the vertical direction), the vibration isolation spring  140  moves together with the valve element  40  and the support member  100 . At this time, since the vibration isolation spring  140  presses the upper wall surface  24   a  of the valve chamber  24  of the valve body  11  with a predetermined force, when the vibration isolation spring  140  moves in a sliding motion, a frictional force is generated between the projected portion  142   d  of the leg portions  242  and the upper wall surface  24   a  of the valve chamber  24 . In this way, the valve element  40  and the support member  100  do not respond sensitively in the vertical direction due to the pressure fluctuation of the high-pressure refrigerant from the inlet port  20 , and the vibration in the vertical direction can be prevented or reduced. Further, since the plurality of leg portions  142  of the vibration isolation spring  140  press the upper wall surface  24   a  of the valve chamber  24  at multiple positions, the valve element  40  and the support member  100  do not move easily in the lateral direction against the pressing force due to the pressure fluctuation of the high-pressure refrigerant from the inlet port  20 , and they exert an effect of preventing vibration in the lateral direction. At the same time, the movement of the valve element  40  and the support member  100  in the vertical direction is guided. 
     In addition, since the vibration isolation spring  140  contacts the upper wall surface  24   a  above the inlet hole  20   a  in the valve chamber  24 , the leg portions  142  do not interfere with the inlet hole  20   a,  such that the flow rate and the occurrence of turbulence of the refrigerant can be suppressed and the passing noise of the refrigerant can be reduced. In addition, since the vibration isolation spring  140  is constituted by the radially extending leg portions  142 , the vibration isolation spring can be easily attached in the valve body  11  by simple insertion through the opening portion of the internal screw  11   a  formed at the bottom portion of the valve body  11 . Further, since the vibration isolation spring  140  has a certain cutout depth (the cutout  145 ) on the surface having the base portion  141 , the length of the leg portions  142  can be set to be greater than the height of the vibration isolation spring. Accordingly, the spring constant of the leg portions  142  can be set to be smaller, and the change in force against the deformation of the leg portions  142  can be reduced, such that a more stable sliding resistance can be obtained. In addition, by adopting the same width for the leg portions  142 , the calculation of the spring constant, that is, the design of the first vibration isolation spring  140 , becomes easier. Further, since the leg portions  142  are formed in a direction perpendicular (radial) with respect to a tangent in the circumferential direction of the base portion  141 , the sliding resistance is generated without applying the torsional force of the base portion  141  in the circumferential direction. 
     Second Embodiment 
       FIG. 6  is a plan view illustrating a vibration isolation spring according to a second embodiment. The second embodiment has a configuration in which the vibration isolation spring  140  of the first embodiment is replaced with a vibration isolation spring  240 , and since the rest of the configuration is the same as that of the first embodiment, a description of the shared portions is omitted. 
     The vibration isolation spring  240  includes a base portion  241  and a leg portion  242 . The vibration isolation spring  240  is formed by press-forming a plate member having elasticity, such as stainless steel or an alloy thereof, for example. 
     The base portion  241  is an annular plate-like member that forms the upper portion of the vibration isolation spring  240  and includes a mounting hole  141   a  formed at a center thereof, similar to the first embodiment. 
     A plurality of the leg portions  242  extend from an outer circumferential side of the base portion  241  in a direction perpendicular with respect to a tangent in the circumferential direction; that is to say, radially. In the second embodiment, eight leg portions  242  having the same lengths are provided at regular angular intervals. Each leg portion  242  is composed of an upper portion  242   a,  a bent portion  142   b,  a side portion  142   c  and a projected portion  142   d.  The bent portion  142   b,  the side portion  142   c  and the projected portion  142   d  are the same as in the first embodiment. 
     Herein, although the first embodiment includes an arc-shaped cutout  145 , the second embodiment differs in that a substantially triangular cutout  245  is provided. Accordingly, the length E of the upper portion  242   a  according to the second embodiment is longer than length C of the upper portion  142   a  of the first embodiment. The length of the leg portions  242  of the second embodiment is set to be longer in correspondence thereto. In addition, the outer circumference of the base portion  241  of the second embodiment is set to be smaller than the outer circumference of the base portion  141  of the first embodiment. It should be noted, in consideration of strength and stress concentration, small arc-shaped portions may be formed in the side surfaces of adjacent upper portions  242   a  in the width direction. 
     In the second embodiment, the length of the vibration isolation spring  240  can be further extended by forming the substantially triangular cutout  245 . Accordingly, the spring constant of the leg portions  242  can be further reduced, the change in force of the leg portions  242  with respect to the deformation can be reduced, and a more stable sliding resistance can be achieved. 
     As described above, the first and second embodiments have been described as embodiments of the present invention, but the present invention is not restricted to the embodiments described above, and various modifications are included in the scope of the invention. For example, the present invention is not restricted to those having all the components (structures) provided in the above-described embodiments. In addition, a portion of a configuration of one embodiment may be deleted or replaced with a configuration of the other embodiment, or the configuration of one embodiment may be added to another embodiment. 
     For example, the above-described embodiments illustrate the leg portions  142  and  242  as having eight leg portions  142  of the same length provided at regular angular intervals. If the number of leg portions  142  and  242  is eight, it becomes possible to ensure stability of behavior and sliding resistance while maintaining balance of the gaps between the leg portions, but the present invention is not restricted to these examples. The number of leg portions should merely be two or greater, and the lengths and angular intervals need not be the same. In addition, the leg portions illustrated in the above embodiments can have widths that vary along their length. 
     Furthermore, although the power element  70  illustrated in the embodiments is attached by screws, in addition to this, a configuration can be utilized in which a cylindrical portion is formed on an upper portion of the valve body, the power element  70  is inserted inside of the cylindrical portion, and caulking is performed on the inner side of the cylindrical portion to thereby attach the power element  70 . 
     REFERENCE SIGNS LIST 
     
         
         
           
               10  expansion valve 
               11  valve body 
               20  inlet port 
               20   a  inlet hole 
               24  valve chamber 
               24   a  upper wall surface 
               25  valve seat 
               26  valve hole 
               28  outlet port 
               30  return passage 
               40  valve element 
               44  coil spring 
               60  valve rod 
               70  power element 
               100  support member 
               120  adjusting screw 
               140 ,  240  vibration isolation spring 
               141 ,  241  base portion 
               142 ,  242  leg portion