JP2010031998A - Expansion valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an expansion valve in which there is no error in the detection of a temperature of a low-pressure refrigerant, which has an appropriate time constant, and does not cause hunting without using activated carbon which is costly and takes a lot of man-hours in filling. <P>SOLUTION: The expansion valve includes: an upper pressure working chamber 35 which is formed at an upper part of a diaphragm 32 in a power element 30, and in which the refrigerant is sealed; a lower pressure working chamber 36 formed at a lower part of the diaphragm 32, and communicating with a passage 9 of the low-pressure refrigerant; and a temperature sensitive bar 50 displaced together with the diaphragm 32 to drive a valve element 14, and having a tubular space 55 therein. The tubular space 55 communicates with the upper pressure working chamber 35 by passing through the diaphragm 32, and there is a gas-liquid interface 56 of the sealed refrigerant in the tubular space 55. By the existence of the gas-liquid interface 56, a temperature in the temperature sensitive bar 50 communicating with the upper pressure working chamber 35 is hardly raised, and the detection error is reduced. Furthermore, the time constant of apparent heat transfer becomes large. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigerant expansion valve used in a refrigeration cycle such as an air conditioner or a refrigeration apparatus.

  Conventionally, in order to facilitate mounting and assembly, an expansion valve having a prismatic valve body to which a power element portion is fixed has been used. This expansion valve requires hunting if the response to the refrigerant temperature is too fast. Therefore, it is necessary to have an appropriate heat transfer time constant, and there are the following two types of internal structures.

(Conventional type 1)
FIG. 5 is a longitudinal sectional view showing an expansion valve 1 of a conventional type 1 (see, for example, Patent Document 1). The expansion valve 1 has an upper portion 50a of a temperature sensing rod 50 that serves as a stem constituting an aluminum valve body drive rod. A resin 70 having a low thermal conductivity is inserted into the outer periphery of the temperature sensing rod 50. The resin 70 is integrated so as to be in close contact with the temperature sensing rod 50. As the resin 70, for example, a PPS resin that does not change over time due to the influence of a refrigerant or the like is used.

  The resin 70 is provided in a portion of the temperature sensing rod 50 exposed in the second passage 9 through which the gas-phase refrigerant passes, and the refrigerant vapor from the outlet of the evaporator flowing through the second passage 9 is provided. The temperature is transmitted to the encapsulated refrigerant that becomes the temperature-responsive working fluid in the upper pressure working chamber 35 of the power element portion 30, and the working gas having a pressure corresponding to this temperature is generated.

  Thereby, for example, the non-evaporated low-pressure refrigerant from the evaporator flows into the second passage 9, and even if the low-pressure refrigerant adheres to the resin 70, the resin 70 is a material having low thermal conductivity. The time constant increases and the response characteristic of the expansion valve 1 becomes insensitive. Therefore, even if a sudden change in the heat load of the evaporator, that is, a sudden increase in the heat load of the evaporator occurs, it is possible to avoid the occurrence of a hunting phenomenon in the refrigeration system because the response characteristic of the expansion valve 1 is insensitive.

(Conventional type 2)
In type 2 of FIG. 6 (see, for example, Patent Document 2), a power element portion 30 having a diaphragm 32 is fixed to the valve body 2 adjacent to the second passage 9. The upper pressure working chamber 35 of the power element section 30 partitioned by the diaphragm 32 is hermetically sealed, and a temperature-responsive working fluid (filled refrigerant) is sealed therein.

  In the lower pressure working chamber 36 below the power element portion 30, an extending end of a temperature sensing rod 50 that constitutes a valve body drive rod extending through the second passage 9 from the valve body 14 through the valve body 2 is disposed. And is in contact with the diaphragm 32.

  The temperature sensing rod 50 is formed in a hollow shape, and transmits the temperature of the refrigerant vapor from the outlet of the evaporator flowing through the second passage 9 to the temperature corresponding working fluid enclosed in the hollow temperature sensing rod 50. Then, the pressure corresponding to this temperature is transmitted to the working fluid in the upper pressure working chamber 35 of the power element unit 30. The lower pressure working chamber 36 is communicated with the second passage 9 through a gap around the temperature sensing rod 50 in the valve body 2.

  Accordingly, the diaphragm 32 of the power element section 30 is operated according to the difference between the pressure of the working gas of the temperature-responsive working fluid in the upper pressure working chamber 35 and the pressure of the refrigerant vapor at the outlet of the evaporator in the lower pressure working chamber 36. Under the influence of the urging force of the urging means 16 for the body 14, the valve opening degree of the valve body 14 with respect to the orifice 11 by the temperature sensing rod 50 (that is, the amount of liquid refrigerant flowing into the inlet of the evaporator) is adjusted. adjust.

In order to prevent the hunting phenomenon, an adsorbing substance such as activated carbon 75 is sealed in the hollow temperature sensing rod 50. In such a configuration, by using the activated carbon 75, it takes time until the temperature / pressure equilibrium between the activated carbon 75 and the temperature-responsive working fluid is achieved, which stabilizes the control characteristics of the refrigeration cycle. And in order to prevent that the temperature-pressure characteristic of a temperature expansion valve changes for every activated carbon by the difference in adsorption amount with activated carbon 75, the activated carbon made from phenol is employ | adopted.
JP 09-159324 A JP 2001-33123 A

  In the conventional type 1, a resin 70 is provided on the outer periphery of the temperature sensing rod 50 to increase the time constant by delaying heat transfer from the low-pressure refrigerant.

  However, in this type 1, heat transfer from the gas-phase refrigerant (low-pressure refrigerant) interposed between the refrigerant outlet of the evaporator and the refrigerant inlet of the compressor to the sealed refrigerant above the diaphragm 32 is extremely high. As a result, the influence of heat from the outside air or the valve body 2 made of aluminum on the enclosed refrigerant becomes relatively large, and the temperature of the temperature sensing rod 50 becomes higher than the temperature of the low-pressure refrigerant. Therefore, the detected temperature error in the steady state becomes large with the temperature of the refrigerant stabilized and the refrigerant pressure constant.

  In addition, hunting is more likely to occur as the pressure of the low-pressure refrigerant is lower because the flow rate of the low-pressure refrigerant is lower. However, in this method, the time constant of heat transfer is extremely increased, so that low-pressure refrigerant is most likely to generate hunting. If the time constant is set under a low pressure condition, the response of the valve body 14 becomes extremely slow under a high refrigerant pressure condition such as during cool-down, and the refrigerant does not evaporate sufficiently (the cooling capacity is low). There arises a problem that the cooling capacity is lowered such as liquid back to the compressor.

  Further, the temperature inside the temperature sensing rod 50 is affected by heat transfer from the side of the diaphragm 32 heated by the influence of the ambient temperature.

  Here, according to the experiment by the inventors, the temperature distribution of the conventional type 1 is as follows. The color expression is expressed in accordance with JIS standard “object color name” Z8102, and in descending order of temperature, red, magenta, light magenta, yellow-red, light yellow, light yellow, light yellow-green, light green, light green, In the conventional type 1, the upper cover 33 and the lower cover 34 of the power element unit 30 are red and the upper cover 33 is red, as shown in FIG. Between the top and the diaphragm 32 is red purple, light red purple, yellow red, light yellow, light yellow, light yellow green, yellow green, the upper part of the diaphragm 32 and the temperature sensing rod 50 and the surroundings are light green, The upper and lower middle parts of the hot bar 50 are dark green, and the lower part of the hot bar 50 is light blue-green.

  In this conventional type 1 system, the working fluid (refrigerant) is sealed only in the upper part of the diaphragm, and extends from the light blue-green part in the lower part in contact with the gas-phase refrigerant to the light green in contact with the working fluid. ) There is a temperature difference in the direction.

  In addition, since the sealed refrigerant that drives the diaphragm 32 is sealed in the upper part of the diaphragm 32, the sealed refrigerant in the upper pressure working chamber 35 that drives the diaphragm 32 is actually changed by the temperature distribution of the temperature sensing rod 50. Since the temperature of the low-pressure refrigerant flowing into the second passage 9 is higher than that of the second passage 9, a temperature detection error occurs.

  On the other hand, in the conventional type 2, as shown in FIG. 6, activated carbon 75 is enclosed in the temperature sensing rod 50 so that the inside of the temperature sensing rod 50 is hollow and has a time constant for direct heat transfer to the sealed gas. .

  This is because the charged gas is adsorbed by the activated carbon 75 and guided into the low-pressure refrigerant flow path, so that the error in the refrigerant detection temperature is small, but the activated carbon 75 needs to be filled in the hollow temperature sensing rod 50, which is costly. , It takes man-hours.

  Further, since the enclosed refrigerant is adsorbed by the activated carbon 75, the pressure in the upper pressure working chamber 35 increases as the temperature rises, and MOP (maximum operating pressure) characteristics (the enclosed refrigerant in the sealed space becomes the heating gas). Therefore, the pressure increase in the upper pressure working chamber 35 becomes moderate with respect to the temperature rise, and it is not possible to have the characteristic that the power of the compressor at the time of high load can be reduced.

  The present invention has been made paying attention to such problems existing in the prior art, and its purpose is to detect the temperature detection error of the gas-phase refrigerant without using activated carbon, which is costly and time-consuming for filling. It is an object of the present invention to provide an expansion valve having an appropriate time constant effective for preventing hunting.

  In order to achieve the above object, the present invention employs the following technical means. That is, in the first aspect of the present invention, the first passage (7) through which the liquid refrigerant from the compressor (8) passes, and the gas-phase refrigerant from the evaporator (6) toward the compressor (8) pass through. A valve body (2) having a second passage (9), an orifice (11) provided in the first passage (7), and a valve body (14) for adjusting the amount of refrigerant passing through the orifice (11) ), A power element portion (30) provided on the valve body (2) and having a diaphragm (32) that operates by a pressure difference between the upper and lower sides, and the diaphragm (32) is formed in the power element portion (30). Along with the displacement of the upper pressure working chamber (35) filled with the refrigerant, the lower pressure working chamber (36) formed in the lower part of the diaphragm (32) and communicating with the second passage (9), and the diaphragm (32) Displaced, the upper end is a diaphragm A temperature sensing rod (50) having a cylindrical space (55) inside, the lower end of the other end driving the valve element (14) and having a cylindrical space (55) inside, the cylindrical shape of the temperature sensing rod (50) The space (55) penetrates the diaphragm (32) and communicates with the upper pressure working chamber (35), and a gas-liquid interface (56) of the enclosed refrigerant exists in the cylindrical space (55). Yes.

  According to the first aspect of the present invention, the presence of the gas-liquid interface (56) reduces the temperature detection error of the gas-phase refrigerant. In addition, the presence of the liquid refrigerant makes it difficult for the temperature of the temperature sensing rod (50) to rise, and the apparent heat transfer time constant can be increased, thereby preventing hunting.

  Further, the invention according to claim 2 is characterized in that the temperature sensing rod (50) is made of a metal having lower thermal conductivity than aluminum and copper.

  According to the second aspect of the present invention, by using a metal having low thermal conductivity, the time constant of heat transfer can be set to a relatively large and appropriate value, and hunting can be further prevented.

  In the invention according to claim 3, the metal having a lower thermal conductivity than aluminum and copper is stainless steel.

  According to the third aspect of the present invention, it can be easily constructed of stainless steel.

  In the invention according to claim 4, when the range from the lower surface of the second passage (9) in the valve body (2) to the upper surface of the valve body (2) is a low-pressure refrigerant channel region, the enclosed refrigerant is In the range of 0 ° C. to 40 ° C., the position of the gas-liquid interface (56) is preferably in the cylindrical space (55) of the temperature sensing rod (50), or more preferably in the low-pressure refrigerant channel region. An amount of the encapsulated refrigerant is enclosed in the cylindrical space (55).

  According to the fourth aspect of the present invention, the amount of the enclosed refrigerant can be set within the optimum range within the operating temperature range (0 ° C. to 40 ° C.) of the refrigeration cycle. If the amount is too large, the strength of the expansion valve must be increased, the response characteristics of the valve body change, and the pressure of the low-pressure refrigerant returning to the compressor deviates from the optimum range. If the amount is small, the anti-hunting effect may be impaired.

  In the invention according to claim 5, the wall surface of the temperature sensing rod (50) surrounds the cylindrical space (55) of the temperature sensing rod (50), and the cylindrical space (55) It is characterized in that the wall thickness of the temperature sensing rod (50) is larger than the inner diameter.

  According to the fifth aspect of the present invention, since the wall thickness of the temperature sensing rod (50) is large, the time constant of heat transfer effective for preventing hunting can be increased.

  In the invention according to claim 6, a low heat transfer coefficient layer (60) having a lower heat transfer coefficient than the material of the temperature sensitive bar (50) is formed on the inner wall of the cylindrical space (55) of the temperature sensitive bar (50). It is characterized by providing.

  According to the sixth aspect of the invention, the heat transfer time constant effective for preventing hunting can be increased by the low heat transfer coefficient layer (60) having a low heat transfer coefficient.

  Further, the invention according to claim 7 is characterized in that the low heat transfer coefficient layer comprises a resin layer (60).

  According to the seventh aspect of the present invention, the resin layer (60) can increase the time constant of heat transfer effective for preventing hunting.

  In the invention according to claim 8, the lower inner diameter is smaller than the upper inner diameter on the lower side, which is the valve body (14) side, of the cylindrical space (55) of the temperature sensing rod (50). The cylindrical space (55a) has a cylindrical space upper part (55b) and a cylindrical space bottom part (55a), and the wall thickness of the temperature sensing rod (50) is The cylindrical space bottom (55a) is larger in the circumference than the circumference of the cylindrical space upper part (55b).

  According to the eighth aspect of the present invention, the time constant of heat transfer can be increased by increasing the wall thickness of the wall of the temperature sensing rod.

  According to the ninth aspect of the present invention, in the range from 0 ° C. to 40 ° C., the amount of the encapsulated refrigerant in which the position of the gas-liquid interface (56) is in the cylindrical space bottom (55a) is a cylindrical space. (55) It is characterized by being enclosed in.

  According to the ninth aspect of the present invention, the amount of the enclosed refrigerant can be set within the optimum range within the operating temperature range of the refrigeration cycle. Moreover, the thick part of the wall surface of the temperature sensing rod having a large time constant can be interposed in the part where heat is transferred from the gas-phase refrigerant to the gas-liquid interface.

  The invention described in claim 10 is characterized in that a foamed resin is used for the resin layer (60) inside the temperature sensitive rod (50).

  According to the tenth aspect of the present invention, the time constant of heat transfer effective for preventing hunting can be increased with less resin.

  In addition, the code | symbol in the parenthesis as described in a claim and said each means is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIG. This expansion valve is used in a refrigeration cycle of an air conditioner such as an automobile. FIG. 1 shows a longitudinal sectional view of an expansion valve of this embodiment together with an outline of a refrigeration cycle. The expansion valve 1 has a prismatic aluminum valve body 2. The valve body 2 includes a liquid phase interposed in a portion of the refrigerant pipe 3 through which the refrigerant (fluorocarbon) of the refrigeration cycle flows from the refrigerant outlet of the condenser 4 to the refrigerant inlet of the evaporator 6 via the receiver 5. The first passage 7 through which the refrigerant passes is provided.

  Further, the valve body 2 has a second passage 9 through which a gas phase refrigerant (low-pressure refrigerant) interposed in a portion from the refrigerant outlet of the evaporator 6 toward the refrigerant inlet of the compressor 8 passes. And the 1st channel | path 7 and the 2nd channel | path 9 are formed mutually spaced apart up and down.

  In the first passage 7, an orifice 11 is formed for adiabatic expansion of the liquid refrigerant supplied from the refrigerant outlet of the receiver 5. The orifice 11 has a shape along the longitudinal direction of the valve body 2. A valve seat 12 is formed at the inlet of the orifice 11, and a valve body 14 supported by a valve member 13 is disposed on the valve seat 12 so as to be seated or separated.

  The valve body 14 and the valve member 13 are fixed by welding. The valve member 13 is biased by a biasing means including a compression coil spring 16 in a direction in which the valve body 14 is pressed against the valve seat 12. The compression coil spring 16 urges the valve member 13 and the valve body 14 in a direction in which the orifice 11 is closed by the valve body 14.

  The first passage 7 into which the liquid refrigerant from the receiver 5 is introduced serves as a passage for the liquid refrigerant, and has an inlet port 17 and a valve chamber 18 continuing to the inlet port 17. The valve chamber 18 is a bottomed chamber formed coaxially with the center line of the orifice 11 and is sealed by a plug 19.

  Further, in order to open and close the orifice 11 by applying a driving force to the valve body 2 according to the temperature of the refrigerant at the refrigerant outlet of the evaporator 6 to the valve body 2, the small diameter hole 20 and the small diameter hole 20 are provided. A large-diameter hole 21 having a diameter larger than that of the hole 20 communicates with the second passage 9 and is formed on an extension line of the center line of the orifice 11.

  In addition, a screw hole 31 is formed at the upper end of the valve body 2 to which the power element portion 30 serving as a heat sensitive portion is fixed. The power element section 30 includes a stainless steel diaphragm 32 and an upper cover 33 and a lower cover 34 provided in close contact with each other with the diaphragm 32 interposed therebetween.

  The upper cover 33 and the lower cover 34 respectively form an upper pressure working chamber 35 and a lower pressure working chamber 36 that form two airtight chambers above and below the diaphragm 32. The upper pressure working chamber 35 is provided with a sealing plug 40 for sealing a sealed refrigerant serving as a diaphragm driving fluid.

  The lower pressure working chamber 36 communicates with the second passage 9 through a pressure equalizing hole 42 formed concentrically with the center line of the orifice 11. Refrigerant vapor (vapor phase refrigerant) from the evaporator 6 flows through the second passage 9, and the pressure of the refrigerant vapor is applied to the lower pressure working chamber 36 via the pressure equalizing hole 42. Further, the lower pressure working chamber 36 and the pressure equalizing hole 42 communicate with each other via a clearance around the umbrella-shaped portion 50 b of the temperature sensing rod 50.

  Further, a stainless steel temperature sensitive rod 50 and a stainless steel working rod 51 are provided from the lower pressure working chamber 36 to the second passage 9 and the small diameter hole 20.

  The temperature sensing rod 50 constitutes a stem, and the wide upper portion 50a of the temperature sensing rod 50 is in contact with the diaphragm 32 and can pass through the second passage 9 and slide into the large-diameter hole 21. Is arranged.

  The temperature sensing bar 50 senses the temperature of the low-pressure refrigerant flowing through the second passage 9. That is, the temperature sensing rod 50 transmits the temperature of the refrigerant at the refrigerant outlet of the evaporator 6 to the upper pressure working chamber 35 and responds to the displacement of the diaphragm 32 due to the pressure difference between the upper pressure working chamber 35 and the lower pressure working chamber 36. Thus, the valve body 14 is given a driving force by sliding in the large-diameter hole 21.

  The operating rod 51 is slidably disposed in the small-diameter hole 20 and presses the valve element 14 against the elastic force of the biasing means 16 in accordance with the displacement of the temperature sensing rod 50.

  The temperature sensing rod 50 and the operation rod 51 are in contact with each other, and the operation rod 51 is in contact with the valve body 14, and the temperature sensing rod 50 and the operation rod 51 are connected to a valve body drive rod (hereinafter referred to as valve body drive rods 50, 51). Called).

  Therefore, the valve body drive rods 50 and 51 extending from the lower surface of the diaphragm 32 to the orifice 11 through the second passage 9 are concentrically disposed in the pressure equalizing hole 42. Further, the lower pressure working chamber 36, the pressure equalizing hole 42, and the second passage 9 are in communication.

  The upper pressure working chamber 35 above the diaphragm 32 is filled with a sealed refrigerant serving as a known diaphragm driving fluid. This diaphragm driving fluid communicates with the cylindrical space 55 of the temperature sensing rod 50, and the heat of the refrigerant vapor from the refrigerant outlet of the evaporator 6 flowing through the second passage 9 is in the space 55. It is transmitted to the refrigerant sealed in.

  Pressure generated at the gas-liquid interface is transmitted to the diaphragm driving fluid in the upper pressure working chamber 35 in response to the heat transmitted to the refrigerant in the space 55, and this pressure is applied to the upper surface of the diaphragm 32. . The diaphragm 32 includes a pressure of the diaphragm driving gas applied to the upper surface and a pressure applied to the lower surface of the diaphragm 32 (that is, a gas phase refrigerant interposed in a portion from the refrigerant outlet of the evaporator 6 to the refrigerant inlet of the compressor 8). It is displaced up and down due to the difference in pressure.

  The vertical displacement of the central portion of the diaphragm 32 is transmitted to the valve body 14 via the valve body drive rods 50 and 51, causing the valve body 14 to approach or separate from the valve seat 12 of the orifice 11. As a result, the refrigerant flow rate is controlled.

  That is, the temperature of the gas-phase refrigerant on the outlet side of the evaporator 6 is transmitted to the enclosed refrigerant in the space 55, and the pressure generated in the space 55 is transmitted to the upper pressure working chamber 35. Accordingly, the pressure in the upper pressure working chamber 35 changes.

  When the outlet temperature of the evaporator 6 rises, that is, when the heat load of the evaporator 6 increases, the pressure in the upper pressure working chamber 35 increases, and the valve body drive rods 50 and 51 are driven downward accordingly. Since the valve body 14 is lowered, the opening of the orifice 11 is increased.

  Thereby, the supply amount of the refrigerant to the evaporator 6 is increased, and the temperature of the evaporator 6 is lowered. On the contrary, when the outlet temperature of the evaporator 6 decreases, that is, when the heat load of the evaporator 6 decreases, the valve body 11 is driven in the reverse direction to the above, and the opening degree of the orifice 11 becomes small. This reduces the amount of refrigerant supplied and raises the temperature of the evaporator 6.

  In a refrigeration system in which such an expansion valve 1 is used, a so-called hunting phenomenon is known in which the supply of refrigerant to the evaporator 6 repeats excess, deficiency, excess, and deficiency in a short cycle. This is due to, for example, the fact that unvaporized liquid refrigerant adheres to the temperature sensing rod 50 and gets wet, and this is detected as a temperature change, and a sensitive opening / closing response of the valve body 14 is performed.

  When such a hunting phenomenon occurs, the capacity of the entire refrigeration system is reduced and liquid return to the compressor 8 occurs.

  Therefore, in this embodiment, the temperature sensing rod 50 is made of a metal material (for example, stainless steel) having a relatively low heat transfer coefficient compared to copper or aluminum, and has a bottomed cylindrical space 55 at the center. is doing.

  The temperature sensing rod 50 and the diaphragm 32 are joined airtightly by welding or the like, and the upper pressure working chamber 35 above the diaphragm 32 and the cylindrical space 55 of the temperature sensing rod 50 communicate with each other.

  Furthermore, when the range (height H portion) from the lower surface of the second passage 9 in the valve body 2 to the umbrella-shaped portion 50b of the temperature sensing rod 50 on the upper surface of the valve body 2 is defined as the low-pressure refrigerant channel region, In the range of 0 ° C. to 40 ° C., the position of the gas-liquid interface (56) is preferably within the cylindrical space (55) of the temperature sensing rod (50) or more preferably An amount of the enclosed refrigerant in the low-pressure refrigerant flow path region is enclosed in the cylindrical space (55). This enclosed refrigerant may be the same as or different from the refrigerant in the refrigeration system compressed by the compressor.

  In addition, since the pressure with respect to temperature is determined by the predetermined relationship, it is preferable that the enclosed refrigerant in the cylindrical space 55 is in a saturated state at a temperature within the use range. For this purpose, not only gas but also liquid exists in the cylindrical space 55, and as a result, it is necessary that a gas-liquid interface exists. Moreover, it is preferable that the said gas-liquid interface exists in the range which detects temperature.

  As described above, the conventional type 1 shown in FIG. 5 receives heat transfer from the side of the diaphragm 32 heated by the influence of the ambient temperature, so that the temperature inside the temperature sensing rod 50 is not uniform, and the temperature sensing rod 50 is not uniform. It has a longitudinal temperature difference (temperature distribution) inside. In addition, the sealed refrigerant that drives the diaphragm 32 is sealed only in the upper part of the diaphragm 32. For this reason, due to the temperature rise of the temperature sensing rod 50 due to the influence of the ambient temperature, the refrigerant outlet temperature of the evaporator 6 is erroneously detected as being higher, and the opening / closing response of the valve body 14 is performed.

  On the other hand, in this embodiment, since the metal material (stainless steel) having better heat conductivity than the resin is used on the outer peripheral side of the temperature sensing rod 50 in FIG. 1, the temperature of the refrigerant in the refrigeration cycle is stabilized, When the pressure of the low-pressure refrigerant is substantially constant, the temperature inside the temperature sensing rod 50 in contact with the low-pressure refrigerant from the evaporator 6 becomes uniform, and the low-pressure refrigerant flowing in the second passage 9 and the enclosure in the upper pressure working chamber 35 are enclosed. The temperature difference of the refrigerant is small.

  Here, according to the inventor's experiment, the temperature distribution is as follows. The color expression is expressed in accordance with JIS standard “object color name” Z8102, and in descending order of temperature, red, magenta, light magenta, yellow-red, light yellow, light yellow, light yellow-green, light green, light green, In this embodiment, if the green, light blue-green, dark blue-green, bluish gray, and blue are used, the upper cover 33 and the lower cover 64 of the power element unit 30 are red as shown in FIG.

  Further, the inside of the upper cover 33 and the lower cover 34 becomes reddish purple, light reddish purple, yellow red and light yellow from the top, and the portion close to the lower cover 34 of the temperature sensing rod 50 is light yellow and light yellow from above. It became green and yellowish green, and the upper and lower middle portions of the temperature sensing rod 50 became green, dark blue-green, and bluish gray from the top, and the lower portion of the temperature sensing rod 50 became blue.

  Thus, in this embodiment, the working fluid is also sealed in the hollow portion in the working rod 51, and the gas-liquid interface in which the pressure is determined is in the small diameter portion. In this case, the portion for detecting the gas-phase refrigerant and the internal gas-liquid interface are both in the blue portion and there is substantially no temperature difference. In other words, temperature distribution is not possible at the gas-liquid interface inside the temperature sensing rod and the portion in contact with the low-pressure refrigerant.

  Further, the pressure of the enclosed refrigerant having the gas-liquid interface 56 for driving the diaphragm 32, that is, the pressure in the upper pressure working chamber 35 is determined by the temperature inside the temperature sensing rod 50 where the gas-liquid interface 56 exists, and the evaporator 6 The opening / closing response of the valve body 14 can be accurately performed by the temperature of the gas-phase refrigerant (low-pressure refrigerant) interposed in the portion from the refrigerant outlet to the refrigerant inlet of the compressor 8. For this reason, detection errors are reduced.

  In addition, the temperature sensing rod 50 is made of stainless steel having a low heat transfer coefficient among metal materials, and compared with a cylindrical space 55 that contains an enclosed refrigerant having a gas-liquid interface 56 inside the temperature sensing rod 50. The wall thickness of the temperature sensing rod 50 is increased. Thus, a time constant necessary for delaying heat transfer with respect to the temperature change of the low-pressure refrigerant is provided.

  As described above, in this embodiment, it is not necessary to enclose activated carbon or the like in the inside, and the cost and man-hour can be reduced. On the other hand, by providing the gas-liquid interface 56 of the encapsulated refrigerant in the temperature sensing rod 50. Even if the necessary time constant is secured, there is no possibility of erroneous detection of temperature during steady state.

  In addition, since no adsorbent such as activated carbon is used inside, by adjusting the amount of the enclosed refrigerant having the gas-liquid interface 56, it is possible to provide MOP characteristics in which the enclosed refrigerant becomes a heated gas at a set temperature. .

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 2 is a longitudinal sectional view of the expansion valve 1 of this embodiment. In the following embodiments, the same components as those in the first embodiment described above are denoted by the same reference numerals, description thereof will be omitted, and different configurations and features will be described.

  In this embodiment, a resin layer 60 having a heat transfer coefficient lower than that of a metal is provided in the cylindrical space 55 of the temperature sensing rod 50. By providing the resin layer 60, the thickness of the temperature sensing rod 50 that has the same time constant in heat transfer can be reduced, and the weight of the expansion valve 1 can be reduced. Further, since the volume of the cylindrical space 55 serving as an internal refrigerant enclosure space can be secured with the same outer diameter of the temperature sensing rod 50, the gas-liquid interface 56 is felt even if the refrigerant enclosure amount is increased. It fits in the hot rod 50. Therefore, the set temperature of the MOP characteristic (the temperature at which the liquid disappears) in which the sealed refrigerant becomes all the heated gas at the set temperature can be set high, and the degree of freedom of the control characteristics increases.

  Furthermore, since the space inside the temperature sensing rod 50 is relatively large with respect to the enclosed space 35 above the diaphragm 32, the thermal influence from the upper part of the diaphragm 32 can be further reduced.

  On the other hand, the amount of liquid refrigerant in the temperature sensing rod 50 can be increased, so that the amount of liquid refrigerant in the temperature sensing rod 50 increases when the pressure of the low-pressure refrigerant that is likely to cause hunting is low. As a result, the heat capacity of the refrigerant in the temperature sensing rod 50 is increased and the time constant of heat transfer is increased, so that hunting is less likely to occur even if the pressure of the low-pressure refrigerant is reduced.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 3 is a longitudinal sectional view of the expansion valve 1 of this embodiment. Features different from the above-described embodiment will be described. In the present embodiment, a foamed resin is used for the resin layer 60 inside the temperature sensing rod 50, whereby the resin layer can be made thinner than in the second embodiment, and the inside of the temperature sensing rod 50 is made of a foamed resin. By directly molding, the manufacturing process can be simplified as compared with the case where a separately molded resin material is inserted.

  Further, since the gas inside the temperature sensing rod 50 is in a gas-liquid two-phase state, the liquid refrigerant is stored in the cylindrical space bottom 55a of the bottomed cylindrical space 55. For this reason, by increasing the thickness of the metal layer made of stainless steel on the wall surface around the cylindrical space bottom 55a, the heat transfer to the liquid refrigerant can be moderately slowed, and the outside of the temperature sensing rod 50 having the same time constant. The diameter can be reduced.

  In other words, the cylindrical space 55 of the temperature sensing rod 50 has a cylindrical space bottom portion 55a whose lower inner diameter is smaller than the upper inner diameter on the lower side, which is the valve body 14 side, and has a cylindrical shape. The space 55 includes a cylindrical space upper portion 55b and a cylindrical space bottom portion 55a. The wall thickness of the temperature sensing rod 50 is greater at the periphery of the cylindrical space bottom 55a than at the periphery of the cylindrical space upper portion 55b. Therefore, since the gas-liquid interface 56 exists in the cylindrical space bottom 55a, the time constant of heat transfer due to the wall thickness of the temperature sensing rod 50 can be further increased.

The longitudinal cross-sectional view of the expansion valve in 1st Embodiment of this invention. The longitudinal cross-sectional view of the expansion valve in 2nd Embodiment of this invention. The longitudinal cross-sectional view of the expansion valve in 3rd Embodiment of this invention. The temperature distribution characteristic view of the expansion valve in the said 1st Embodiment. The longitudinal cross-sectional view of the expansion valve in the conventional type 1. FIG. The longitudinal cross-sectional view of the expansion valve in the conventional type 2. FIG. The temperature distribution characteristic view of the expansion valve in the conventional type 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Expansion valve 2 ... Valve body 4 ... Condenser 6 ... Evaporator 7 ... 1st channel | path 8 ... Compressor 9 ... 2nd channel | path 11 ... Orifice 12 ... Valve seat 13 ... Valve member 14 ... Valve body 30 ... Power Element part 32 ... Diaphragm 35 ... Upper pressure working chamber 36 ... Lower pressure working chamber 50 ... Temperature sensing rod 51 ... Actuating rod 50, 51 ... Valve element driving rod 55 ... Cylindrical space 55a ... Cylindrical space bottom 55b ... Cylindrical space upper part 56 ... Gas-liquid interface 60 ... Resin layer

Claims (10)

A valve body having a first passage (7) through which liquid refrigerant from the compressor (8) passes, and a second passage (9) through which vapor-phase refrigerant from the evaporator (6) toward the compressor (8) passes. (2) and
An orifice (11) provided in the first passage (7);
A valve body (14) for adjusting the amount of refrigerant passing through the orifice (11);
A power element portion (30) having a diaphragm (32) provided on the valve body (2) and operated by a pressure difference between the upper and lower sides;
In the power element portion (30), an upper pressure working chamber (35) formed at the upper portion of the diaphragm (32) and filled with an enclosed refrigerant, and a second passage (formed at the lower portion of the diaphragm (32)). 9) a lower pressure working chamber (36) in communication with
A temperature sensing rod that is displaced along with the displacement of the diaphragm (32), one end of which is in contact with the diaphragm (32), the other end is driven by the valve body (14), and a cylindrical space (55) is provided inside. (50)
The cylindrical space (55) of the temperature sensing rod (50) passes through the diaphragm (32) and communicates with the upper pressure working chamber (35), and the tubular space (55) An expansion valve characterized by the presence of a gas-liquid interface (56) of the enclosed refrigerant. The expansion valve according to claim 1, wherein the temperature sensing rod (50) is made of a metal having a lower thermal conductivity than aluminum and copper. The expansion valve according to claim 2, wherein the metal having a lower thermal conductivity than aluminum and copper is stainless steel.   When the range from the lower surface of the second passage (9) in the valve main body (2) to the upper surface of the valve main body (2) is a low-pressure refrigerant flow region, the enclosed refrigerant is 0 ° C to 40 ° C. In such a range, the amount of the gas-liquid interface (56) is preferably in the cylindrical space (55) of the temperature sensing rod (50), or more preferably in the low-pressure refrigerant flow path region. The expansion valve according to any one of claims 1 to 3, wherein the sealed refrigerant is sealed in the cylindrical space (55).   A wall surface of the temperature sensing rod (50) is surrounded around the cylindrical space (55) of the temperature sensing rod (50), and the sensitivity is larger than the inner diameter of the cylindrical space (55). The expansion valve according to any one of claims 1 to 4, characterized in that the wall thickness of the warm rod (50) is greater.   A low heat transfer coefficient layer (60) having a heat transfer coefficient lower than that of the material of the temperature sensing rod (50) is provided on the inner wall of the cylindrical space (55) of the temperature sensing rod (50). The expansion valve according to any one of claims 1 to 5.   The expansion valve according to claim 6, wherein the low heat transfer coefficient layer comprises a resin layer (60).   A cylindrical space bottom (55a) having a lower inner diameter smaller than an upper inner diameter on the lower side, which is the valve body (14) side, of the cylindrical space (55) of the temperature sensing rod (50). The cylindrical space (55) includes a cylindrical space upper part (55b) and a cylindrical space bottom part (55a), and the wall thickness of the temperature sensing rod (50) is the bottom part of the cylindrical space. The expansion valve according to any one of claims 1 to 7, wherein the circumference of (55a) is larger than the circumference of the upper cylindrical space (55b).   In the range of 0 ° C. to 40 ° C., the amount of the enclosed refrigerant in which the position of the gas-liquid interface (56) is in the cylindrical space bottom (55a) is enclosed in the cylindrical space (55). The expansion valve according to claim 8.   The expansion valve according to claim 7, wherein a foamed resin is used for the resin layer (60) inside the temperature sensing rod (50).

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