Abstract:
An expansion valve includes a valve body having a valve body hole, a first passage, a bottomed valve chamber, a second passage, a third passage and a guide member disposed in the valve body hole between the first passage and the third passage. The valve body hole has a first valve body hole portion and a second valve body hole portion of different diameters forming a valve body step between the second passage and the first passage. The guide has a first guide portion and a second guide portion of different diameters forming a guide portion step. The guide is sized to be slidably received by the valve body hole in a close-fitting relationship with the first valve body hole portion receiving the first guide portion, the second valve body hole portion receiving the second guide portion and the valve body step and the guide portion step contacting each other.

Description:
The present application is based on and claims priority of Japanese patent applications No. 2004-146294 filed on May 17, 2004, and No. 2004-207257 filed on Jul. 14, 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 which is mounted in an air conditioner for an automobile and the like for controlling the flow rate of a refrigerant supplied to an evaporator according to the temperature of the refrigerant. 
   2. Description of the Related Art 
   An expansion valve of this type has been disposed, for example, in Japanese Patent Laid-Open Publication No. 2002-310538 (Patent Document 1). 
   The conventional expansion valve disclosed in Patent Document 1 requires a large number of parts such as a valve receiving member, a spring, and an adjusting screw, so that it is difficult to achieve the miniaturization and lightweight of expansion valve. 
   Furthermore, there is a fear that a refrigerant leaks from a valve chamber through an adjusting screw portion. 
   SUMMARY OF THE INVENTION 
   Accordingly, an object of the present invention is to provide an expansion valve in which the construction thereof is simplified to meet the demand for compactness and lightweight of an air conditioner for an automobile, and the manpower for assembly is decreased. 
   In addition, another object of the present invention is to provide an expansion valve capable of achieving stabilization of valve motion with respect to fluctuations in pressure of a high-pressure refrigerant by using simple and low-cost means. 
   Moreover, further object of the present invention is to provide an expansion valve, in the state in which the above-described objects are achieved, with a space (wall thickness) with respect to a mounting hole for mounting the expansion valve to an evaporator and the like secured without causing corrosion of a valve body, and without fearing leakage of refrigerant. 
   Furthermore, another object of the present invention is to provide an expansion valve in which by threadedly engaging an external thread portion of a mounting seat for a can body of a driving device with an internal thread portion of a driving device mounting hole of a valve body, the driving device is installed in the driving device mounting hole of the valve body, and a seal member is brought into close contact with the outer periphery of the mounting seat for the can body of the driving device, by which leakage of a refrigerant from between the inner periphery of the driving device mounting hole of the valve body and the outer periphery of the mounting seat for the can body of the driving device can be prevented, and by rotating the external thread portion of the mounting seat for the can body of the driving device in the tightening direction or the loosening direction with respect to the internal thread portion of the driving device mounting hole of the valve body, an operation rod can be moved vertically together with the driving device, and a set value for starting the opening of a valve element can be finely adjusted by the amount of engagement of the external thread portion of the mounting seat for the can body of the driving device with the internal thread portion of the driving device mounting hole of the valve body. 
   To achieve the above objects, the present invention takes the measures described below. 
   An expansion valve of a first aspect of the invention includes a valve body, a first passage formed in the valve body through which a high-pressure refrigerant passes, a bottomed valve chamber formed in the first passage, a second passage formed in parallel with the first passage in the valve body through which a refrigerant sent out to the evaporator side passes, a third passage for allowing a refrigerant sent out from the evaporator side to pass through, and a guide member arranged in an opening portion of the valve body, and is characterized in that in the guide member, a guide portion, which slidably guides an operation rod for opening and closing a valve element, and an orifice portion, which has a throttle portion for causing the valve chamber and the second passage to communicate with each other are formed integrally, a passage communicating with the second passage is formed between the guide portion and the orifice portion, the valve element is arranged so as to be opposed to the throttle portion, and the operation rod is driven by a driving device mounted on the valve body. 
   An expansion valve of a second aspect of the invention is characterized in that, in the expansion valve of the first aspect of the invention, the guide member is fixed by staking to the valve body. 
   An expansion valve of a third aspect of the invention is characterized in that, in the expansion valve of the first aspect of the invention, the guide member forms the valve body and a positioning portion. 
   An expansion valve of a fourth aspect of the invention is characterized in that, in the expansion valve of the third aspect of the invention, the positioning portion is formed by a step portion of the guide member. 
   An expansion valve of a fifth aspect of the invention is characterized in that, in the expansion valve of the first aspect of the invention, the orifice portion is inserted under pressure in the valve body. 
   An expansion valve of a sixth aspect of the invention is characterized in that, in the expansion valve of the fourth aspect of the invention, the step portion abuts on the valve body in a state in which it is maintained by sealing. 
   An expansion valve of a seventh aspect of the invention is characterized in that, in the expansion valve of the sixth aspect of the invention, the abutting portion is fixed to the valve body by surface contact. 
   An expansion valve of an eighth aspect of the invention is characterized in that, in the expansion valve of the first aspect of the invention, the orifice portion of the guide member forms the valve body and a positioning portion. 
   An expansion valve of a ninth aspect of the invention is characterized in that, in the expansion valve of the eighth aspect of the invention, the positioning portion is formed by a step portion of the valve body. 
   An expansion valve of a tenth aspect of the invention is characterized in that, in the expansion valve of the eighth or the ninth aspect of the invention, the guide member is fixed by staking to the valve body. 
   An expansion valve of an eleventh aspect of the invention is characterized in that, in the expansion valve of any one of the first to the tenth aspects of the invention, the guide member is provided with a vibration isolating member abutting on the operation rod. 
   An expansion valve of a twelfth aspect of the invention is characterized in that, in the expansion valve of any one of the first to the eleventh aspects of the invention, at least a part of a large-diameter portion of the guide member, which incorporates the vibration isolating member, is arranged in the third passage. 
   An expansion valve of a thirteenth aspect of the invention is characterized in that, in the expansion valve of the twelfth aspect of the invention, a seal groove is formed at the outer periphery of the orifice portion, and a ring seal is arranged in the seal groove. 
   An expansion valve of a fourteenth aspect of the invention is characterized in that, in the expansion valve of any one of the first to the thirteenth aspects of the invention, the valve body is formed with a driving device mounting hole, which communicates with the third passage, for mounting the driving device, an annular groove and an internal thread portion are formed at the inner periphery of the driving device mounting hole in the valve body, the driving device has a can body fixed to the driving device mounting hole in the valve body, the can body of the driving device is integrally formed with a cylindrical mounting seat fitted in the driving device mounting hole in the valve body, an external thread portion threadedly engaged with the internal thread portion of the driving device mounting hole in the valve body is formed at the outer periphery of a tip end part of the mounting seat of the driving device, and a seal member in close contact with the outer peripheral surface of the mounting seat of the driving device is arranged in the annular groove of the driving device mounting hole in the valve body. 
   An expansion valve of a fifteenth aspect of the invention is characterized in that, in the expansion valve of the fourteenth aspect of the invention, the seal member is an O-ring. 
   An expansion valve of a sixteenth aspect of the invention is characterized in that, in the expansion valve of the fourteenth aspect of the invention, in the can body of the driving device, a diaphragm displaced by sensing the temperature of a refrigerant sent out of the evaporator and a stopper member for transmitting the displacement of the diaphragm to the operation rod are provided, a cylindrical hollow protrusion is integrally formed on the stopper member, a proximal end part of the operation rod is inserted in the hollow protrusion of the stopper member, and a distal end of the operation rod abuts on the valve element. 
   As described above, the expansion valve in accordance with the present invention is formed with the opening portion with the inner diameter dimension of which decreases gradually from the opening side on which a power element is installed with respect to the valve body of the expansion valve is formed, and the bottomed hole is formed in a distal end part thereof. 
   Further, the guide member integrally having the valve element and the orifice portion are inserted under pressure or fitted in the opening portion to guide the operation rod, and the throttle portions of the high pressure side and the low pressure side for a refrigerant are defined. 
   By this configuration, the number of parts of expansion valve can be reduced, and the manpower for assembly can be decreased. Also, the guide member integrally having the orifice portion is inserted under pressure or fitted, and is fixed by staking, by which the guide member can be positioned, and also the leakage of refrigerant can be prevented. 
   Moreover, since the vibration isolating member is arranged, vibrations of valve element of the expansion valve caused by the fluctuations in pressure of a refrigerant are restrained so that the valve function can be stabilized. Further, since the vibration isolating member has a simple construction, the fabrication thereof is easy and the vibration isolating member can be mounted to the valve body easily. Therefore, an expansion valve that is easy to handle and has high usability can be realized. 
   Further, since vibration isolating springs of a ring member is brought into contact with and supported on the operation rod so as to be in point contact, even if the operation rod somewhat tilts, a smooth supporting state is held. 
   Further, since the space (wall thickness) between a stepped hole in which the guide member is inserted under pressure and a mounting hole for mounting the expansion valve to an evaporator and the like is secured, without causing corrosion of a valve body in an expansion valve, and without any fear of leakage of refrigerant is provided in an expansion valve. 
   Further, the external thread portion of the mounting seat for the can body of the driving device is threadedly engaged with the internal thread portion of the driving device mounting hole of the valve body, by which the driving device is installed in the driving device mounting hole of the valve body, and the seal member is brought into close contact with the outer periphery of the mounting seat for the can body of the driving device. Therefore, the leakage of refrigerant from between the inner periphery of the driving device mounting hole of the valve body and the outer periphery of the mounting seat for the can body of the driving device can be prevented. Furthermore, by rotating the external thread portion of the mounting seat for the can body of the driving device in the tightening direction or the loosening direction with respect to the internal thread portion of the driving device mounting hole of the valve body, the operation rod can be moved vertically together with the driving device. A set value for starting the opening of the valve element can be finely adjusted by the amount of engagement of the external thread portion of the mounting seat for the can body of the driving device with the internal thread portion of the driving device mounting hole of the valve body. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view of an expansion valve in accordance with Example 1 of the present invention; 
       FIG. 2  is a right side view of  FIG. 1 ; 
       FIG. 3  is an enlarged sectional view of a guide member shown in  FIG. 1 ; 
       FIG. 4  is an enlarged sectional view of a principal portion of  FIG. 1 ; 
       FIG. 5  are views showing another example of a guide member shown in  FIG. 1 ,  FIG. 5(A)  being a front view and  5 (B) being a sectional view; 
       FIG. 6  are views showing another example of a guide member shown in  FIG. 1 ,  FIG. 6(A)  being a front view and  6 (B) being a sectional view; 
       FIG. 7  is a sectional view of a principal portion of another example of the present invention; 
       FIG. 8  is a perspective view of a vibration isolating member shown in  FIG. 1 ; 
       FIG. 9  is a perspective view of a vibration isolating member of Example 2; 
       FIG. 10  is a perspective view showing a state in which the vibration isolating member shown in  FIG. 9  is mounted in a guide member; 
       FIG. 11  is a plan view showing a state in which an operation rod is mounted in the vibration isolating member shown in  FIG. 9 ; 
       FIG. 12  is a perspective view of a vibration isolating member of Example 3; 
       FIG. 13  is a perspective view showing a state in which the vibration isolating member shown in  FIG. 11  is mounted in a guide member; 
       FIG. 14  are views of the vibration isolating member shown in  FIG. 12 ,  FIG. 14(A)  being a partial explanatory view and  FIG. 14(B)  being a side view of a principal portion; 
       FIG. 15  is a plan view showing a state in which an operation rod is mounted in the vibration isolating member shown in FIG.  12 ; 
       FIG. 16  are views of a vibration isolating member of Example 4,  FIG. 16(A)  being a partial explanatory view and  FIG. 16(B)  being a side view of a principal portion; 
       FIG. 17  is a plan view showing a state in which an operation rod is mounted in the vibration isolating member shown in  FIG. 16 ; 
       FIG. 18  are views of a vibration isolating member of Example 5,  FIG. 18(A)  being a partial explanatory view and  FIG. 18(B)  being a side view of a principal portion; 
       FIG. 19  is a plan view showing a state in which an operation rod is mounted in the vibration isolating member shown in  FIG. 18 ; 
       FIG. 20  is a sectional view of an expansion valve of Example 6 of the present invention (sectional view taken along the line X-X line of  FIG. 21 ); 
       FIG. 21  is a right side view of  FIG. 20 ; 
       FIG. 22  is a sectional view of an expansion valve of Example 7 of the present invention; and 
       FIG. 23  is a right side view of  FIG. 22 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Preferred examples of the present invention will now be described. 
   EXAMPLE 1 
     FIG. 1  is a sectional view of an expansion valve in accordance with Example 1 of the present invention,  FIG. 2  is a right side view of  FIG. 1 ,  FIG. 3  is an enlarged sectional view of a guide member shown in  FIG. 1 ,  FIG. 4  is an enlarged sectional view of a principal portion of  FIG. 1 ,  FIGS. 5(A) and 5(B)  are a front view and a sectional view, respectively, of another example of a guide member shown in  FIG. 1 , and  FIGS. 6(A) and 6(B)  are a front view and a sectional view, respectively, of another example of a guide member shown in  FIG. 1 . 
   An expansion valve, the whole of which is denoted by reference number  1 , has a valve body  10  having a circular hole in a central part thereof, the outer surface of which is formed of an aluminum alloy and the like and is of a prismatic shape, and the valve body  10  is provided with a first passage  20  through which a high-pressure refrigerant flows. 
   The first passage  20  communicates with a valve chamber  22  having a bottom  22   a , and an orifice portion  40  formed integrally with a guide member  100  is fixed under pressure in an opening portion of the valve chamber  22 . 
   Further, spherical valve element  30 , which is installed by welding to a support member  32 , is arranged in the valve chamber  22 . The support member  32  always urges the valve element  30  toward the orifice portion  40  by means of a spring  34 . 
   As shown in  FIG. 3 , the cylindrical guide member  100  provided in the valve body  10  includes a guide portion  102  formed with an operation rod hole  101  in the axis portion thereof, a cylindrical large-diameter portion  121  having a step portion on its peripheral portion and formed integrally with the guide portion  102  via a step portion  110 , and the orifice portion  40  integrally formed via a passage  43  of the guide portion  102  with respect to the valve body  10 . As shown in  FIGS. 1 and 4 , a step portion  13  formed on the valve body  10  is in surface contact with the step portion  110  of the guide member  100 , and thereby the guide member  100  is fixed by being positioned exactly, so that the sealing is secured by the surface contact of the step portion  110  with the step portion  13 . 
   The passage of refrigerant between a second passage  24  and a third passage  26  may be sealed by inserting a ring-shaped seal member (not shown) in an inner-diameter part of the guide member  100 . 
   Further, as shown in  FIGS. 1 and 4 , the orifice portion  40  communicating with the second passage  24 , which is formed via the passage  43  formed at the lower part of the guide member  100 , has a throttle portion  42 , which causes the valve chamber  22  to communicate with the passage  43 , in a central part thereof, so that a flow path for the refrigerant is formed between the orifice portion  40  and the valve element  30 . 
   The refrigerant having passed through the orifice portion  40  is sent out to the evaporator (not shown) side through the passage  43  and the second passage  24 . 
   The refrigerant returning from the evaporator is sent to the compressor (not shown) side through the third passage  26 . 
   As shown in  FIGS. 3 and 4 , in an upper part of the guide portion  102 , the large-diameter portion  121  arranged in a stepped hole  14  is formed, and a vibration isolating member  50  is arranged in a large-diameter hole portion  120  and mounted on an operation rod  60 , by which the operation rod  60  is prevented from vibrating. 
   Further, the columnar guide portion  102  is formed continuously with the large-diameter portion  121 , and the operation rod  60  is slidably guided in a central part thereof. In a peripheral part at the lower end of the orifice portion  40 , a guide portion  44  having the outer periphery of which has a small diameter at the lower end is formed. 
   The guide portion  102  of the guide member  100  having the above-described construction is fixed by staking to the valve body  10 . 
   Specifically, an end part  122  of the large-diameter portion, which is an upper end part of the guide member  100 , is fixed by staking to the valve body  10  by using a staking part  11  (refer to  FIG. 4 ) formed on the valve body  10  side. 
   Therefore, the guide member  100  of this example is fixed by staking to the valve body  10 , and also the orifice portion  40  of the guide member  100  is fixed under pressure to the valve body  10 , so that the guide member  100  is fixed to the valve body  10  reliably. 
   In addition, the orifice portion  40  is fixed by ensured sealing because it is pressed in. 
   Furthermore, since the guide member  100  is brought into surface contact with the valve body  10  by the step portion  110 , the step portion  110  acts as a positioning portion at the time when the guide member  100  is fixed, and also can surely provide the sealing by means of the surface contact. 
   Accordingly, the leakage of refrigerant from the second passage  24  to the third passage  26  can be prevented. 
   Thus, the leakage of refrigerant from the first passage  20  to the second passage  24  and the leakage of refrigerant from the second passage  24  to the third passage  26  can be prevented. 
   The guide portion  44  having a small diameter in the orifice portion  40  is formed by a wall portion  44 ′ formed by being erected integrally with a circular edge part of a disc portion  45 , and a flat portion  46  continuous with the wall portion  44 ′ and a tilt portion  47  are connected to the throttle portion  42 . 
   The valve element  30  is provided so as to be arranged in the tilt portion  47  and be opposed to the throttle portion  42 . 
   As shown in  FIG. 5 , as another example, an orifice portion  40 ′ in a lower part of the guide member  100  may have a shape such that the guide portion (refer to  FIG. 3 ) is not formed and the vertical length is short to simplify the fabrication of the guide member  100 . 
   Further, as another example, as shown in  FIGS. 6(A) and 6(B) , an orifice member  40 ″ may be made as a member separate from the guide member  100  to improve the handling ability. 
   If the orifice member  40 ″ is made as a member separate from the guide member  100 , in mounting the guide member  100  in the valve body  10 , the guide member  100  is mounted after the orifice member  40 ″is first mounted through an opening  12 . 
   As shown in  FIG. 1 , in an end part on the side opposite to the valve chamber  22  of the valve body  10 , a driving device  70  for the valve element  30 , which is called a power element, is installed. 
   The power element  70  has a can body  72  in which an upper lid  72   a  and a lower lid  72   b  are welded integrally, and a diaphragm  80  is held between the upper lid  72   a  and the lower lid  72   b.    
   The can body  72  is fixed to the valve body  10  by a threaded portion  74 , and is sealed by a seal member  76 . 
   Between the diaphragm  80  and the upper lid  72   a , a pressure chamber  82  is formed, which is filled with a working fluid and is sealed by a plug  84 . 
   On the side opposite to the pressure chamber  82  of the diaphragm  80 , a stopper member  90  is disposed. 
   The refrigerant in the third passage  26  is introduced to the back surface of the stopper member  90  through the opening  12 . 
   The stopper member  90  slides in response to the displacement of the diaphragm  80 . 
   The stopper member  90  holds the operation rod  60 , and the distal end of the operation rod  60  abuts on the valve element  30 . 
   The displacement of the diaphragm  80  drives the valve element  30  via the operation rod  60  to control a flow path area between the valve element  30  and the orifice portion  40 . 
   In the above explanation of examples, the case where the orifice portion  40  of the guide member  100  is fixed under pressure and the guide member  100  is fixed by staking has been described. However, it is a matter of course that the present invention is not limited to these examples, and an orifice portion  240  of a guide member  200  may be brought into contact with the valve body  10  to ensure the sealing. 
     FIG. 7  is a sectional view of the guide member  200 , which is a principal portion of another example in which the orifice portion is in contact with the valve body. 
   In  FIG. 7 , the valve body  10  is formed with a step portion  15 , and the orifice portion  240  of the guide member  200  is in surface contact with the step portion  15 , by which the sealing is ensured. 
   Specifically, the orifice portion  240  formed integrally with the guide member  200  is formed by a disc portion  245  formed with a throttle portion  242  in the center thereof and a wall portion  244  formed integrally with the disc portion  245  by being erected downward from the peripheral edge of the disc portion  245 . The wall portion  244  is arranged in an opening part of the valve chamber  22  of the valve body  10  with a predetermined clearance being provided, and an end part  244   b  of the wall portion  244  is in surface contact with the step portion  15  to constitute a positioning portion. 
   Furthermore, a guide portion  202  which is formed integrally with the orifice portion  240  to constitute the guide member  200  is fixed by staking by using the staking part  11  provided on the valve body  10 . 
   Stake fixing is performed by staking an end part  222  of the guide portion  202  by using the staking part  11 . 
   Thus, the guide member  200  is positioned by the positioning portion  244   b  and is fixed to the valve body  10 . 
   By the above-described construction, the sealing is ensured by the positioning portion  244   b . Therefore, even if the high-pressure refrigerant introduced into the first passage  20  leaks to the second passage  24  side, the leakage is prevented by the positioning portion  244   b.    
   Further, in the orifice portion  240 , the wall portion  244  and the throttle portion  242  of the disc portion  245  are connected to each other by a flat portion  246  and a tilt portion  247 , and the valve element  30  is arranged in the tilt portion  247  so as to be opposed to the throttle portion  242 . 
   Furthermore, it is a matter of course that the aforementioned leakage can be prevented by fixing by staking the guide portion  202  to the valve body  10  by using the staking part  11  of the valve body  10 . 
   Therefore, according to this example, the leakage of refrigerant from the first passage  20  to the second passage  24  and the leakage of refrigerant from the second passage  24  to the third passage  26  can be prevented. 
   In a large-diameter hole portion  220  of the guide portion  202 , as in the example shown in  FIG. 3 , the vibration isolating member  50  is arranged, and is mounted on the operation rod  60 , by which the operation rod  60  is prevented from vibrating. 
     FIG. 8  is a perspective view showing a construction of the vibration isolating member  50 . 
   The vibration isolating member  50  has a ring portion  52  formed by curving a metal sheet with high elasticity into a circular shape and vibration isolating springs  54  each formed by notching the ring portion  52  and bending the notched portion to the inner side. 
   The ring portion  52  is constructed so that both end parts  52   a  and  52   b  are lapped on each other. The vibration isolating member  50  is inserted into an inner-diameter part of the large-diameter hole portion  120  in the guide member  100  in a state in which the diameter of the ring portion  52  is decreased, by which the vibration isolating member  50  can be positioned on the inner side of the guide member  100  by utilizing a elastic force restoring the diameter. 
   The vibration isolating springs  54  are in contact with the outer periphery of the rod-shaped operation rod  60 , and thereby restrains the vibrations of the valve element  30 . 
   Although three vibration isolating springs  54  are provided in this example, four vibration isolating springs can be provided. 
   Next, the procedure for assembling this expansion valve will be explained. 
   First, the support member  32  to which the spring  34  and the valve element  30  have been welded is inserted into the bottomed valve chamber  22  through the opening  12  on the side on which the power element  70  of the valve body  10  is installed. 
   Next, the guide member  100  to which the vibration isolating member  50  has been installed and in which the operation rod  60  has been inserted is inserted under pressure into the stepped hole  14  in the valve body  10  through the opening  12 . 
   The guide member  100  is positioned in the axial direction by the step portion  110 , and is fixed by staking (using the staking part  11 ). 
   Finally, an assembly of the power element  70  is threadedly engaged with the valve body  10  by the threaded portion  74 , by which the assembly of the expansion valve  1  is completed. 
   EXAMPLE 2 
   Next, Example 2 will be explained with reference to  FIGS. 9 to 11 . 
     FIG. 9  is a perspective view of a vibration isolating member of Example 2,  FIG. 10  is a perspective view showing a state in which the vibration isolating member shown in  FIG. 9  is mounted in a guide member, and  FIG. 11  is a plan view showing a state in which an operation rod is mounted in the vibration isolating member shown in  FIG. 9 . 
   As shown in  FIG. 11 , the vibration isolating member (ring member  150 ) shown in  FIGS. 9 and 10  is used to support the operation rod  60 . 
   As shown in  FIG. 9 , the vibration isolating member of Example 2 is formed by the ring member  150  including one annularly-shaped ring portion  152  and three plate-shaped vibration isolating springs  154  arranged on one side of the ring portion  152 . 
   Also, for this ring member  150 , as in Example 1, a cross part is formed in an end part of a plate body forming the ring portion  152 , and as this cross part, narrow tongue elements  152   a  and  152   b  with the same curvature as that of the ring portion  152  are extended from both end parts of the ring portion  152 . 
   The shape, material, and number of the vibration isolating springs  154  are the same as those in the case of Example 1. 
   According to the ring member  150  constructed as described above, in the state in which the ring member  150  is mounted in the guide member  100 , as shown in  FIG. 11 , the periphery of the operating rod  60  is supported by the vibration isolating springs  154  at three places, and the ring member  152  acts as a vibration isolating member for the valve element  30 . 
   Therefore, even if fluctuations in refrigerant pressure occur in a refrigerating cycle, the motion of the valve element  30  can be stabilized, so that the flow rate of refrigerant can be controlled exactly, and the noise generated by the vibrations of the operation rod  60  can be prevented. 
   In the above-described example, the vibration isolating spring  154  is formed so as to have the same width through the whole length. However, needless to say, the vibration isolating spring  154  may have other shapes, for example, it may be formed so as to have a triangular shape with a tip end part thereof being a vertex to adjust the degree of elasticity. 
   EXAMPLE 3 
   Next, Example 3 will be explained with reference to  FIGS. 12 to 15 . 
     FIG. 12  is a perspective view of a vibration isolating member of Example 3,  FIG. 13  is a perspective view showing a state in which the vibration isolating member shown in  FIG. 12  is mounted in a guide member,  FIGS. 14(A) and 14(B)  area partial explanatory view and a side view of a principal portion, respectively, of a vibration isolating member shown in  FIG. 12 , and  FIG. 15  is a plan view showing a state in which an operation rod is mounted in the vibration isolating member shown in  FIG. 12 . 
   In Example 3, the vibration isolating member (ring member  250 ) shown in  FIGS. 12 to 14  is used to support the operation rod  60  as in Examples 1 and 2. 
   As in Examples 1 and 2, the operation rod  60  is driven by the power element  70  as shown in  FIG. 1 . 
   Also, the ring member  250  is fitted in the large-diameter portion  120  formed in the guide member  100  shown in  FIG. 5  as in Examples 1 and 2. 
   A ring portion  252  of the ring member  250  is mounted so as to be in elastic contact with the inner side wall of the large-diameter portion  120 . 
   For the ring member  250  of Example 3, as shown in  FIGS. 12 to 15 , a semispherical spherical surface portion  256  is formed in a tip end part of each of three flat-plate shaped vibration isolating springs  254  formed on the inner surface of the ring portion  252 , and the spherical surface portions  256  support the operation rod  60  so as to be in point contact with the side surface of the operation rod  60 . 
   Also, as shown in  FIGS. 12 to 14 , the ring portion  252  is formed with notches  56  along the lengthwise direction thereof. 
   The ring portion  252  is constructed so that both end parts  252   a  and  252   b  are lapped on each other. The vibration isolating member  250  is inserted into the inner-diameter part of the large-diameter hole portion  120  in the guide member  100  in a state in which the diameter of the ring portion  252  is decreased, by which the vibration isolating member  250  can be positioned on the inner side of the guide member  100  by utilizing a elastic force for restoring the diameter. 
   Therefore, according to Example 3, the periphery of the operation rod  60  is supported by the three vibration isolating springs  254  at three places so that the semispherical spherical surface portion  256  formed in the tip end part of each of the three flat-plate shaped vibration isolating springs  254  is in point contact with the side surface of the operation rod  60 . Therefore, the ring member  250  acts as a vibration isolation for the operation rod  60 . Even if fluctuations in refrigerant pressure occur in a refrigerating cycle, the motion of the valve element  30  can be stabilized, so that the flow rate of refrigerant can be controlled exactly, and the noise generated by the vibrations of the valve element  30  can be prevented. 
   Further, according to Example 3, since the ring member  250  is arranged in a portion of the operation rod  60  separate from the flow path of refrigerant as in Examples 1 and 2, the ring member  250  does not impart flow resistance to the refrigerant. Further, there is no fear that the ring member  250  itself generates vibrations or noise caused by the flow of refrigerant. 
   Furthermore, as shown in  FIG. 15 , since the vibration isolating spring  254  of the ring member  250  is in point contact with the operation rod  60 , even if the operation rod  60  somewhat tilts, a smooth supporting state is held. 
   EXAMPLE 4 
   Next, Example 4 will be explained with reference to  FIGS. 16 and 17 . 
     FIGS. 16(A) and 16(B)  are a partial explanatory view and a side view of a principal portion, respectively, of a ring member of Example 4, and  FIG. 17  is a plan view showing a state in which an operation rod is mounted in the ring member shown in  FIG. 16 . 
     FIG. 16(B)  is a view taken in the direction of the arrow of  FIG. 16(A) . 
   Example 4 is a modification of Example 3. As in Examples 1 to 3, a vibration isolating member (ring member  350 ) shown in  FIGS. 16 and 17  is fitted in the large-diameter portion  120  formed in the guide member  100  shown in  FIG. 15 . 
   For the ring member  350 , three vibration isolating springs  354  integral with a ring portion  352  are formed on the inner side of the ring portion  352 , and a tip end part of each of the springs  354  is bent into a chevron shape in the same direction. Also, a curved protrusion  356  of a cylindrical peripheral surf ace shape is formed in the tip end part, so that the curved protrusions  356  support the operation rod  60  so as to be in point contact with the peripheral surface of the operation rod  60 . 
   According to the above-described construction, the ring member  350  acts as a vibration isolating member for the valve element  30  via the operation rod  60 . Therefore, even if fluctuations in refrigerant pressure occur in a refrigerating cycle, the motion of the valve element  30  can be stabilized, so that the flow rate of refrigerant can be controlled exactly, and the noise generated by the vibrations of the valve element  30  can be prevented. 
   Further, according to Example 4, since the ring member  350  is arranged in a portion of the operation rod  60  separate from the flow path of refrigerant as in other examples, the ring member  350  does not impart flow resistance to the refrigerant. Further, there is no fear that the ring member  350  itself generates vibrations or noise caused by the flow of refrigerant. 
   Furthermore, since the vibration isolating spring  354  of the ring member  350  is in point contact with the operation rod  60 , even if the operation rod  60  somewhat tilts, or even if the vibration isolating spring  354  is elastically deformed, a smooth supporting state is held. 
   EXAMPLE 5 
   Next, Example 5 will be explained with reference to  FIGS. 18 and 19 . 
     FIGS. 18(A) and 18(B)  are a partial explanatory view and a side view of a principal portion, respectively, of a ring member of Example 5, and  FIG. 19  is a plan view showing a state in which an operation rod is mounted in the ring member shown in  FIG. 18 . 
     FIG. 18(B)  is a view taken in the direction of the arrow of  FIG. 18(A) . 
   Example 5 is a modification of Example 4. In Example 5, a vibration isolating member (ring member  450 ) is used to support the operation rod  60  as in Example 4. 
   As in other examples, the ring member  450  is fitted in the large-diameter portion  120  of the guide member  100 . 
   For the ring member  450 , as shown in  FIGS. 18(A) and 18(B)  and  FIG. 19 , three vibration isolating springs  454  integral with a ring member  452  are formed on the inner side of the ring member  452 , and a tip end part of each of the springs  454  is bent in the same direction. Also, a protrusion  456  is formed in the tip end part, so that the protrusions  456  support the operation rod  60  so as to be in point contact with the peripheral surface of the operation rod  60 . 
   According to the above-described construction, the ring member  450  acts as a vibration isolating member for the valve element  30  via the operation rod  60 . Therefore, even if fluctuations in refrigerant pressure occur in a refrigerating cycle, the motion of the valve element  30  can be stabilized, so that the flow rate of refrigerant can be controlled exactly, and the noise generated by the vibrations of the valve element  30  can be prevented. 
   Further, according to Example 5, the same effects as those of the other examples can be anticipated. 
   EXAMPLE 6 
   In the case where Example 1 shown in  FIG. 1  is adopted, since the stepped hole  14  having a large diameter, which is formed in the valve body  10 , and mounting holes  10   a  and  10   b  (refer to  FIG. 21 ) for mounting the expansion valve to an evaporator and the like are arranged close to each other, there arises a problem in that a wall thickness between these holes cannot be secured. 
   Accordingly, a technique described in Example 6 has been invented as a solution to the above-described problem. 
   Hereunder, Example 6 will be explained with reference to  FIGS. 20 and 21 . 
     FIG. 20  is a sectional view of an expansion valve of Example 6 of the present invention (sectional view taken along the line X-X of  FIG. 21 ), and  FIG. 21  is a right side view of  FIG. 20 . 
   In  FIGS. 20 and 21 , the same reference numbers as those in  FIGS. 1 to 4  are applied to the same elements as those in Example 1, and the explanation thereof is omitted. 
   Example 6 is characterized in that the ring-shaped vibration isolating member  50  is installed in the third passage  26  as shown in  FIG. 20 . 
   Specifically, in the case of Example 6, as shown in  FIGS. 20 and 21 , the valve body  10  is formed with a small-diameter hole portion  16  and a large-diameter hole portion  17  (corresponding to the stepped hole  14  in Example 1), in which a guide member  500  is inserted, and is formed so that the vertical length (height) of the small-diameter hole portion  16  is long and the vertical length (height) of the large-diameter hole portion  17  is short as compared with Example 1 (especially, refer to  FIG. 4 ). 
   The guide member  500  is formed so that a uniform-diameter portion constituting a lower part thereof is long as compared with Example 1, and hence is formed so that most of an increased-diameter portion  521  is located in the third passage  26  when the guide member  500  is fitted in the small-diameter hole portion  16  and the large-diameter hole portion  17 . 
   The vibration isolating member  50  is arranged in this increased-diameter portion  521  as in other examples. 
   By this construction, the large-diameter hole portion  17  can be provided at a position separate from the mounting holes  10   a  and  10   b , so that the space (wall thickness) between the large-diameter hole portion  17  and the mounting holes  10   a  and  10   b  in the valve body  10  can be secured while the function of the vibration isolating member  50  is kept. 
   Therefore, also in Example 6, the same vibration isolating effect as that of Example 1 is achieved, preventing the corrosion of the valve body  10 , so that a fear of refrigerant leakage can be dispelled. 
   Also, as shown in  FIG. 20 , an annular seal groove  541  is formed at the outer periphery of an orifice portion  540  at a lower part of the guide member  500 , and a ring seal  550  is fitted in the seal groove  541 , by which the sealing between the valve chamber  22  and the second passage  24  can be improved. 
   EXAMPLE 7 
   Next, Example 7 will be explained with reference to  FIGS. 22 and 23 . 
     FIG. 22  is a sectional view of an expansion valve of Example 7 of the present invention, and  FIG. 23  is a right side view of  FIG. 22  of the same. 
   The expansion valve, the whole of which is denoted by reference number  1 , has the prismatic valve body  10  formed of an aluminum alloy and the like, and the valve body  10 , which is provided with through holes  28  for mounting, is formed with the first passage  20  into which a high-pressure refrigerant flows. 
   The first passage  20  communicates with the bottomed valve chamber  22 , and an orifice member  640  is fixed under pressure at the opening of the valve chamber  22 . 
   In the valve chamber  22 , the spherical valve element  30  is installed to the support member  32  by welding, and the support member  32  always urges the valve element  30  toward the orifice member  640  by means of the spring  34 . 
   The orifice member  640  has an opening  642  in a central part to form a flow path for refrigerant between the orifice member  640  and the valve element  30 . 
   In an inner-diameter part of the orifice member  640 , a vibration isolating member  650  is fitted to prevent the valve element  30  from vibrating. 
   The refrigerant having passed through the orifice member  640  is sent out to the evaporator side through the second passage  24 . 
   The refrigerant returning to the evaporator is sent to the compressor side through the third passage  26 . 
   In an end part on the side opposite to the valve chamber  22  of the valve body  10 , the driving device  70  for the valve element  30 , which is called a power element, is installed. 
   The power element  70  has the can body  72  in which the upper lid  72   a  and the lower lid  72   b  are welded integrally, and the diaphragm  80  is held between the upper lid  72   a  and the lower lid  72   b.    
   The can body  72  is fixed to the valve body  10  by the threaded portion  74 , and is sealed by an O-ring  677 , which is a seal member. 
   Between the diaphragm  80  and the upper lid  72   a , the pressure chamber  82  is formed, which is filled with a working fluid and is sealed by the plug  84 . 
   On the side opposite to the pressure chamber  82  of the diaphragm  80 , the stopper member  90  is disposed. 
   The refrigerant in the third passage  26  is introduced to the back surface of the stopper member  90  through the opening  12 . 
   The stopper member  90  slides in response to the displacement of the diaphragm  80 . 
   The stopper member  90  holds the operation rod  60 , and the distal end of the operation rod  60  abuts on the valve element  30 . 
   The displacement of the diaphragm  80  drives the valve element  30  via the operation rod  60  to control the flow path area between the valve element  30  and the orifice member  640 . 
   A guide member  600  in which the valve body  10  is inserted under pressure has a stepped portion  610 , and is positioned exactly with respect to the valve body  10  and is fixed. 
   In an inner-diameter part of the guide member  600 , a ring-shaped seal member  620  is inserted, and is fixed by a fastener  630  such as a bush nut. 
   The seal member  620  inhibits the passage of refrigerant between the second passage  24  and the third passage  26 . 
   The valve body  10  is formed with a driving device mounting hole  627  which communicates with the third passage  26  and is open to install the power element  70 , and an annular groove  628  and an internal thread portion  629  are formed at the inner periphery of the driving device mounting hole  627  of the valve body  10 . 
   On the lower lid  72   b  of the can body  72  of the power element  70 , a cylindrical mounting seat  673  fitted in the driving device mounting hole  627  of the valve body  10  is formed integrally. At the outer periphery of a tip end part of the mounting seat  673  for the can body  72  of the power element  70 , an external thread portion  674  threadedly engaged with the internal thread portion  629  of the driving device mounting hole  627  of the valve body  10  is formed, and the external thread portion  674  of the mounting seat  673  for the can body  72  of the power element  70  is threadedly engaged with the internal thread portion  629  of the driving device mounting hole  627  of the valve body  10 , by which the power element  70  is threadedly fitted in the driving device mounting hole  627  of the valve body  10 . 
   In the annular groove  628  of the driving device mounting hole  627  of the valve body  10 , the O-ring  677  is arranged as a seal member that is in close contact with the outer peripheral surface of the mounting seat  673  for the can body  72  of the power element  70 . 
   In the can body  72  of the power element  70 , the diaphragm  80  displaced by sensing the temperature of refrigerant sent out of the evaporator and the stopper member  90  for transmitting the displacement of the diaphragm  80  to the operation rod  60  are provided. On the stopper member  90 , a cylindrical hollow protrusion  691  is integrally formed in the center on the lower surface on the side opposite to the diaphragm  80 , and a proximal end part of the operation rod  60  is fitted in the hollow protrusion  691  on the stopper member  90 . The distal end of the operation rod  60  abuts on the valve element  30 . 
   Next, the procedure for assembling this expansion valve will be explained. 
   First, the support member  32  to which the spring  34  and the valve element  30  have been welded is inserted into the valve chamber  22  through the opening  12  on the side on which the power element  70  of the valve body  10  is installed. 
   Then, an assembly of the orifice member  640 , to which the vibration isolating member  650  has been attached, is inserted under pressure into an opening portion  616  of the valve chamber  22  through the opening  12 . 
   To insert the assembly into the opening portion  616 , an appropriate press-in tool is used, and the assembly is fixed by staking as necessary. 
   Next, the guide member  600  in which the operation rod  60  has been inserted is inserted under pressure into a stepped hole  614  in the valve body  10  through the opening  12 . 
   The guide member  600  is positioned in the axial direction by the stepped portion  610 . 
   As necessary, the guide member  600  is fixed by staking. 
   Finally, the O-ring  677  is fitted in the annular groove  628  of the driving device mounting hole  627  of the valve body  10 , and the mounting seat  673  for the can body  72  of the power element  70  is fitted in the driving device mounting hole  627  of the valve body  10 . The external thread portion  674  of the mounting seat  673  for the can body  72  of the power element  70  is threadedly engaged with the internal thread portion  629  of the driving device mounting hole  627  of the valve body  10  and is tightened, and accordingly an assembly of the power element  70  is threadedly engaged with the valve body  10  by the threaded portion  74 , by which the assembly of the expansion valve  1  is completed. 
   According to the above-described configuration, the external thread portion  674  of the mounting seat  673  for the can body  72  of the power element  70  is threadedly engaged with the internal thread portion  629  of the driving device mounting hole  627  of the valve body  10  and is tightened, by which the power element  70  is installed in the driving device mounting hole  627  of the valve body  10 , and the O-ring  677  is brought into close contact with the outer periphery of the mounting seat  673  for the can body  72  of the power element  70 . Therefore, the leakage of refrigerant from between the inner periphery of the driving device mounting hole  627  of the valve body  10  and the outer periphery of the mounting seat  673  for the can body  72  of the power element  70  can be prevented surely by the O-ring  677 . 
   Further, by rotating the external thread portion  674  of the mounting seat  673  for the can body  72  of the power element  70  in the tightening direction or the loosening direction with respect to the internal thread portion  629  of the driving device mounting hole  627  of the valve body  10 , the power element  70  is moved vertically with respect to the driving device mounting hole  627  of the valve body  10 , by which the operation rod  60  can be moved vertically together with the power element  70 . A set value for starting the opening of the valve element  30  of the expansion valve  1  can be finely adjusted by the amount of engagement of the external thread portion  674  of the mounting seat  673  for the can body  72  of the power element  70  with the internal thread portion  629  of the driving device mounting hole  627  of the valve body  10 .