Expansion valve

CROSS-REFERENCE TO RELATED APPLICATIONS, IF ANY

This application claims priorities of Japanese Application No. 2005-060795 filed on Mar. 4, 2005, entitled “EXPANSION VALVE”, No. 2005-212618 filed on Jul. 22, 2005, entitled “EXPANSION VALVE”, No. 2005-356373 filed on Dec. 9, 2005, entitled “EXPANSION VALVE” and No. 2006-012969 filed on Jan. 20, 2006, entitled “EXPANSION VALVE”.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to an expansion valve which is disposed in a refrigeration cycle, for throttling and expanding refrigerant introduced from an upstream side and delivering the refrigerant to a downstream side.

(2) Description of the Related Art

In general, a refrigeration cycle for an automotive air conditioner comprises a compressor that compresses refrigerant circulating through the refrigeration cycle, a condenser that condenses the compressed refrigerant, a receiver that stores the refrigerant circulating through the refrigeration cycle and separates the condensed refrigerant into a gas and a liquid, an expansion valve that throttles and expands liquid refrigerant obtained by gas/liquid separation, and an evaporator that evaporates the expanded refrigerant.

As the expansion valve of the above-mentioned components, a temperature expansion valve, for example, is used which senses the temperature and pressure of refrigerant in an outlet of the evaporator, and controls the flow rate of refrigerant to be sent to the evaporator. This temperature expansion valve includes a body formed with a first passage for passing refrigerant flowing from the receiver to the evaporator, and a second passage for passing refrigerant returning from the evaporator and delivering the refrigerant to the compressor. At an intermediate portion of the first passage of the body, there is provided a valve section for adjusting the flow rate of refrigerant, and at an end of the body toward the second passage, there is provided a power element for sensing the temperature and pressure of refrigerant flowing through the second passage, thereby controlling the valve lift of the valve section via a drive shaft. (see e.g. Japanese Unexamined Patent Publication (Kokai) No. 2000-304382).

By the way, the body of the expansion valve configured as above is generally manufactured by forming an aluminum alloy light in weight and excellent in machining property into a solid semi-finished product by extrusion molding, and then machining the body by cutting the first passage, the second passage, the connection portion of the power element, and so forth. However, the cutting process takes a long machining time period and is low in yield, resulting in increased manufacturing costs of the expansion valve.

In view of this, a technique for manufacturing the body by hollow extrusion has been proposed (see e.g. Japanese Unexamined Patent Publication (Kokai) No. 10-267470).

In this technique, attention is paid to the fact that the second passage may have a simple, straight shape, and this passage is formed simultaneously with formation of the body by extrusion molding. As a result, it is possible to dispense with a hole-forming process for cutting the second passage and save the aluminum material, thereby making it possible to enhance manufacturing efficiency of the body to some extent.

However, the above extrusion including the hollow extrusion can be applied only to straight-shaped portions having a fixed cross section, since it is necessary to extrude an aluminum alloy in a predetermined extruding direction. This makes it impossible to apply the extrusion to the formation of the first passage with which a valve seat as a component part of a valve section is integrally formed in an intermediate portion thereof. Further, although at ends of the first and second passages, there are formed sealing surfaces of sealing members which are interposed for connection of pipes connected to the compressor, the receiver, and the evaporator, the sealing surfaces cannot be formed by extrusion molding, since the end portions are diametrically expanded. Therefore, as for these portions, there is still no other way but employ machining by cutting, which makes it impossible to sufficiently reduce the amount of used materials and enhance manufacturing efficiency.

Further, when the second passage is formed by the hollow extrusion, and then the ends thereof are to be cut by a lathe, for example, it is not easy to cause the axis of the passage during extrusion molding and the axis of the rotating shaft during a cutting process to coincide with each other. Therefore, for example, when an attempt is made to form a sealing portion by a tool, such as a drill, the axis of the tool can be eccentric with respect to the axis of the passage, and eccentric load can act on the tool and the body during machining, which can cause machining problems.

Further, although it is contemplated to employ a method of manufacturing the body by injection molding of a resin material, resin materials are inferior to metal materials in rigidity and strength, and produce larger flow noises of refrigerant. Moreover, a resin material once cured is difficult to plastically deform, and even when the valve section is about to be coined in accordance with the shape of the valve element, the resin material does not easily conform to dies, which is liable to cause fracture during machining. This makes it necessary to perform insert molding of a valve section separately formed of a metal, during injection molding, which makes the manufacturing process cumbersome.

It should be noted that the above-described problems are not only suffered by the temperature expansion valve but also by electromagnetic expansion valves and the like.

SUMMARY OF THE INVENTION

The present invention has been made in view of the problems, and an object thereof is to enhance the manufacturing efficiency of a body of an expansion valve and yield from material, thereby reducing manufacturing costs of the expansion valve.

To solve the above problem, according to the present invention, there is provided an expansion valve that introduces refrigerant from an upstream side thereof and throttles and expands the refrigerant by passing the refrigerant through a valve section formed therein, to supply the refrigerant to a downstream side thereof, wherein a body including a valve seat as a component part of the valve section is formed by die casting a metal.

Further, according to the present invention, there is provided an expansion valve that introduces refrigerant from an upstream side thereof and throttles and expands the refrigerant by passing the refrigerant through a valve section formed therein, to supply the refrigerant to a downstream side thereof, wherein a body having a valve section provided therein is formed by die casting a metal.

The above and other objects, features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of an expansion valve according to a first embodiment.

FIG. 2 is a left side view of the expansion valve.

FIG. 3 is a rear view of the expansion valve.

FIG. 4 is a cross-sectional view taken on line A-A of FIG. 1.

FIG. 5 is a view useful in explaining the outline of essentials of a method of manufacturing the expansion valve.

FIG. 6 is a view useful in explaining a state in which the expansion valve has been mounted at a boundary between a vehicle compartment and an engine room.

FIG. 7 is a cross-sectional view taken on line B-B of FIG. 6.

FIGS. 8A, 8B and 8C are views useful in explaining the construction of a variation of the expansion valve according to the first embodiment.

FIGS. 9A, 9B and 9C are views useful in explaining the construction of a variation of the expansion valve according to the first embodiment.

FIGS. 10A, 10B and 10C are views useful in explaining the construction of a variation of the expansion valve according to the first embodiment.

FIG. 11 is a front view of an expansion valve according to a second embodiment.

FIG. 12 is a left side view of the expansion valve.

FIG. 13 is a rear view of the expansion valve.

FIG. 14 is a cross-sectional view taken on line C-C of FIG. 11.

FIG. 15 is a front view of an expansion valve according to a third embodiment.

FIG. 16 is a left side view of the expansion valve.

FIG. 17 is a right side view of the expansion valve.

FIG. 18 is a rear view of the expansion valve.

FIG. 19 is a cross-sectional view taken on line D-D of FIG. 15.

FIGS. 20A, 20B, 20C and 20D are views useful in explaining the construction of a variation of the expansion valve according to the third embodiment.

FIG. 21 is a perspective view of an expansion valve according to a fourth embodiment.

FIG. 22 is a front view of the expansion valve.

FIG. 23 is a left side view of the expansion valve.

FIG. 24 is a cross-sectional view taken on line E-E of FIG. 22.

FIG. 25 is a cross-sectional view taken on line F-F of FIG. 23.

FIG. 26 is a view useful in explaining the outline of essentials of a method of manufacturing the expansion valve.

FIG. 27 is a rear view of an expansion valve according to a fifth embodiment.

FIG. 28 is a cross-sectional view taken on line G-G of FIG. 27.

FIG. 29 is a cross-sectional view of a variation of the fifth embodiment.

FIG. 30 is a cross-sectional view of an expansion valve according to a sixth embodiment.

FIG. 31 is a left side view of an expansion valve according to a seventh embodiment.

FIG. 32 is a view useful in explaining a state in which the expansion valve has been mounted at the boundary between the vehicle compartment and the engine room.

FIG. 33 is a cross-sectional view taken on line H-H of FIG. 32.

FIG. 34 is a left side view of an expansion valve according to an eighth embodiment.

FIG. 35 is a view useful in explaining a state in which the expansion valve has been mounted at the boundary between the vehicle compartment and the engine room.

FIG. 36 is a cross-sectional view taken on line I-I of FIG. 35.

FIGS. 37A and 37B are views useful in explaining the construction of a body of an expansion valve according to a ninth embodiment.

FIG. 38 is a central longitudinal cross-sectional view of an expansion valve according to a tenth embodiment.

FIGS. 39A, 39B and 39C are views useful in explaining the construction of a valve section and its vicinity of a body.

FIGS. 40A, 40B and 40C are views useful in explaining the construction of a first variation of the expansion valve according to the tenth embodiment.

FIGS. 41A, 41B and 41C are views useful in explaining the construction of a second variation of the expansion valve according to the tenth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First Embodiment

First of all, a first embodiment of the present invention will be described. In the present embodiment, an expansion valve according to the present invention is embodied as a temperature expansion valve that is applied to a refrigeration cycle for an automotive air conditioner. FIG. 1 is a front view of the expansion valve. FIG. 2 is a left side view of the same. FIG. 3 is a rear view of the same. Further, FIG. 4 is a cross-sectional view taken on line A-A of FIG. 1.

As shown in FIGS. 1 to 3, the expansion valve 1 has a body 2 formed by die casting of an aluminum alloy, described hereinafter. The body 2 is generally prism-shaped, and has lightening portions for reducing the weight thereof formed all over its side surfaces. A valve section for throttling and expanding refrigerant is formed inside the body 2, and a power element 3 functioning as a temperature-sensing section is provided at a longitudinal end of the body 2.

As shown in FIG. 4, the body 2 of the expansion valve 1 has sides thereof formed with a port 4 (first port) for receiving high-temperature, high-pressure liquid refrigerant from a receiver (a condenser side), a port 5 (second port) for supplying low-temperature, low-pressure refrigerant throttled and expanded by the expansion valve 1 to an evaporator, a port 6 (third port) for receiving refrigerant evaporated by the evaporator, and a port 7 (fourth port) for returning refrigerant having passed through the expansion valve 1 to a compressor. A first passage 8 is formed by the port 4, the port 5, and a refrigerant passage communicating therebetween, and a second passage 9 is formed by the port 6, the port 7, and a refrigerant passage communicating therebetween. The respective open ends of the port 4 and the port 5 of the first passage 8 are provided with sealing surfaces of sealing members which are interposed between the open ends and pipes connected to the receiver and the evaporator when the pipes are connected to the port 4 and the port 5. The sealing surfaces are formed to be tapered such that they are widened toward the respective open ends. Further, the respective open ends of the port 6 and the port 7 of the second passage 9 are also formed with sealing surfaces of sealing members which are interposed between these open ends and pipes connected to the evaporator and the compressor when the pipes are connected to the port 6 and the port 7. These sealing surfaces as well are formed to be tapered such that they are widened toward the respective open ends.

A valve seat 10 is formed integrally with the body 2 in a portion of the first passage 8 communicating between the port 4 and the port 5, and a valve hole 11 is defined by an inner periphery of the valve seat 10. A ball-shaped valve element 12 as a component part of the valve section is disposed on the upstream side of the valve seat 10. Further, a communication hole 13 (corresponding to an adjustment part), which is approximately orthogonal to the first passage 8 and communicates with the outside, is formed in a lower end of the body 2, and an adjustment screw 14 is screwed into the communication hole 13 to seal the communication hole 13. A spring-receiving member 15 in the form of a circular recess is formed in a foremost end face of the adjustment screw 14, and accommodates and supports one end of a helical compression spring 16 that is interposed between the spring-receiving member 15 and the valve element 12 for urging the valve element 12 in the direction in which the valve element 12 is seated on the valve seat 10. The adjustment screw 14 is configured such that adjustment of the screwing amount thereof into the body 2 can adjust the load of the helical compression spring 16. More specifically, the adjustment screw 14 functions as an adjustment mechanism which can adjust the resilient force of the helical compression spring 16 by having its position within the communication hole 13 adjusted. Further, an O ring 17 is interposed between the adjustment screw 14 and the body 2, for blocking refrigerant within the body 2 from leaking to the outside through the communication hole 13.

Further, a communication hole 18 (corresponding to a temperature-sensing part), which is approximately orthogonal to the second passage 9 and communicates with the outside, is formed in an upper end of the body 2, and the power element 3 is screwed into the communication hole 18 in a manner sealing the communication hole 18. The power element 3 comprises an upper housing 19 and a lower housing 20, both of which are made of stainless steel material, a diaphragm 21 made of a thin metal plate having flexibility and disposed in a manner dividing a space enclosed by the housings, and a disk 22 disposed below the diaphragm 21. A temperature-sensing gas is filled in a temperature-sensing chamber hermetically sealed by the upper housing 19 and the diaphragm 21. Between the power element 3 and the body 2, there is interposed an O ring 23 for blocking refrigerant within the body 2 from leaking to the outside through the communication hole 18. The pressure and temperature of refrigerant passing through the second passage 9 are transmitted to the lower surface of the diaphragm 21 via the communication hole 18 and a hole or slit formed in the disk 22.

A shaft 24 is disposed below the disk 22 for transmitting the displacement of the diaphragm 21 to the valve element 12. The shaft 24 extends through a through hole 25 formed in the body 2. The through hole 25 has a large-diameter portion 25a at an upper location, and a small-diameter portion 25b at a lower location. The large-diameter portion 25a has an upper open end formed to have a shape of a tapered chamfer. An O ring 26 is disposed in the large-diameter portion 25a of the through hole 25, for completely sealing between the shaft 24 and the through hole 25, whereby bypass leakage of refrigerant from the through-hole 25 is completely prevented.

An upper portion of the shaft 24 is held by a holder 27 disposed in a manner crossing the second passage 9. A lower end of the holder 27 is fitted in the large-diameter portion 25a of the through hole 25 such that a lower end face of the holder 27 restricts the motion of the O ring 26 toward the upper open end of the through hole 25. The shaft 24 extends through the small-diameter portion 25b, and a lower end of the shaft 24 reaches the valve hole 11. An upper end of the shaft 24 is in abutment with a lower surface of the disk 22, and the abutment surface of the disk 22 is inclined with respect to a plane orthogonal to the axis of the shaft 24. As a result, the shaft 24 is configured to be given not only axial load but also lateral load by the axial motion of the diaphragm 21. With this configuration, when the motion of the diaphragm 21 is transmitted to the shaft 24, a component of the force as the lateral load is applied to the shaft 24 such that even when there occurs a change in the pressure of high-pressure refrigerant flowing through the fluid passage of the port 4, the motion of the shaft 24 is inhibited from sensitively reacting to the change, whereby the vibration of the shaft 24 in the longitudinal direction thereof is suppressed.

Further, as shown in FIGS. 1 and 4, a screw hole 31 having a predetermined depth is formed in the center of a side surface of the body 2 where the port 4 and the port 7 open (i.e. a surface of the same on an engine room side). The screw hole 31 is provided for fastening a bolt for fixing a fixed plate, not shown, for use in connecting pipes connected to the compressor and the receiver to the ports 7 and 4, when the fixed plate is mounted on the body 2. Further, a pair of dummy holes 32 are formed between the port 7 and the screw hole 31 in the same side surface of the body 2. The dummy holes 32 are provided for inserting bolts for fixing fixed plates, not shown, for use in connecting pipes connected to the evaporator to the ports 6 and 8, when the fixed plates are mounted on the body 2. Furthermore, abutment surfaces 33 and an abutment surface 34 for abutting a tool thereagainst for pushing out a molded body in removing the molded body from a mold after die casting of the body 2, described hereinafter, are formed at two locations of an upper end portion and one location of a lower end portion of the same side surface of the body 2, respectively. As shown in FIG. 2, the pair of the upper abutment surfaces 33 are formed on respective protrusions 35 protruding from the lightening portions such that the upper abutment surfaces 33 are arranged on approximately the same plane as the lower abutment surface 34.

Further, as shown in FIGS. 1 to 3 (best shown in FIG. 3), in the left and right side surfaces (side surfaces approximately parallel to the first passage 8 and the second passage 9) of the body 2, there are formed mounting surfaces 36 for mounting the expansion valve 1 on a fire wall member, described hereinafter, arranged at a boundary between a vehicle compartment and the engine room, and flat surfaces 37 used as holders when the expansion valve 1 is carried by a predetermined apparatus. Although in the present embodiment, the mounting surface 36 and the flat surface 37 are connected on the same plane, this is not necessarily required, but steps may be formed at boundaries therebetween, or the surfaces 36 and 37 may be separated from each other.

It should be noted that the mounting surfaces 36 and the flat surfaces 37 are parts of the outer shape of a normal body, which are intentionally left by taking operability and the like into account when a plurality of lightening portions are formed in the body 2. In other words, to reduce the weight of the body 2 as much as possible while preserving the above convenient shapes, the lightening portions are formed in the respective side surfaces of the body 2. More specifically, the lightening portions 41 are formed in portions of the left and right side surfaces of the body 2, except for the portions formed with the mounting surfaces 36 and the flat surfaces 37, and portions of side surfaces (front and rear surfaces) of the body 2 orthogonal to these faces 36 and 37, except for the respective rims of the first passage 8, the second passage 9, and the screw hole 31. Even lightening portions having the above-described relatively complicated shapes can be easily formed by die casting.

Next, essentials of a method of manufacturing the expansion valve according to the present embodiment will be described. FIG. 5 is a view useful in explaining the outline of the essentials of the method of manufacturing the expansion valve. It should be noted that in an example illustrated in FIG. 5, the shape of the expansion valve is simplified for clarity.

The expansion valve 1 is manufactured by die casting an aluminum alloy. In the present embodiment, an apparatus including a first mold 50, a second mold 60, and a mandrel 70, as shown in FIG. 5, is employed. Chambers for forming the main body, refrigerant passages, and the like of the body 2 are formed by the first mold 50, the second mold 60, and the mandrel 70.

The first mold 50 has a chamber 51 for molding a front half of the body 2 where the ports 4 and 7 are located. Inside the chamber 51, port-forming portions 52 and 53 for forming the respective ports 4 and 7, a screw hole-forming portion 54 for forming a pilot hole of the screw hole 31, and dummy hole-forming portions 55 for forming the pair of dummy holes 32 are formed in a manner protruding toward the opening. Although not shown, root portions of the port-forming portions 52 and 53 have tapered shapes so as to form the aforementioned sealing surfaces of the sealing members. Further, a mandrel insertion portion-forming groove 56 for forming an insertion hole for inserting the mandrel 70, and an injection passage-forming groove 57 for forming an injection passage for injecting a molten aluminum alloy are formed in a manner communicating with the chamber 51. It should be noted that although not shown, the first mold 50 is formed with insertion holes at locations corresponding to the above-mentioned abutment surfaces 33 and 34 of the body 2, for moving predetermined long tools to and away from them.

On the other hand, the second mold 60 has a chamber 61 for molding a rear half of the body 2 where the ports 5 and 6 are located. Inside the chamber 61, port-forming portions 62 and 63 for forming the respective ports 5 and 6 are formed in a manner protruding toward the opening. Although not shown, root portions of the port-forming portions 62 and 63 have tapered shapes so as to form the aforementioned sealing surfaces of the sealing members. Further, a mandrel inserting portion-forming groove 64 for forming the insertion hole for inserting the mandrel 70 together with the mandrel inserting portion-forming groove 56 when the second mold 60 are combined with the first mold 50, and an injection passage-forming groove 65 for forming the injection passage for injecting the molten aluminum alloy in cooperation with the injection passage-forming groove 57 when the second mold 60 are combined with the first mold 50, are formed in a manner communicating with the chamber 61.

Furthermore, the mandrel 70 has a stepped hollow cylindrical shape, and is formed with an adjustment part-forming portion 71 for forming the above-mentioned communication hole 13 (adjustment part), and a valve section-forming portion 72 for forming the valve section (the valve seat 10 and the valve hole 11) in the second passage 8. Particularly, the valve section-forming portion 72 has a tapered inclined surface such that the valve hole 11 is hermetically sealed when the ball-shaped valve element 12 is seated on the valve seat 10, to thereby prevent occurrence of refrigerant leakage, and is configured such that coining can be achieved.

In manufacturing the body 2, the molten aluminum alloy is injected from the injection passage in a state in which the first mold 50, the second mold 60, and the mandrel 70 are assembled with each other, for performing die casting. In the present embodiment, an Al—Si—Cu-based aluminum alloy excellent in castability is employed as the aluminum alloy. More specifically, an aluminum alloy composed of 9.6 to 12.0 wt % of Si, 0 to 1.3 wt % of Fe, 1.5 to 3.5 wt % of Cu, 0 to 0.5 wt % of Mn, 0 to 0.3 wt % of Mg, 0 to 1.0 wt % of Zn, 0 to 0.5 wt % of Ni, 0 to 0.3 wt % of Sn, and Al and unavoidable impurities as the remainder is used. Particularly, the content of 9.6 to 12.0 wt % of Si makes it possible to maintain an excellent fluidity of the molten aluminum alloy. Further, by limiting the content of Cu to 1.5 to 3.5 wt %, it is possible to suppress defects caused by shrinkage of the material.

After the aluminum alloy hardens, the first mold 50 and the second mold 60 are separated from each other after the mandrel 70 is drawn out. At this time, a semi-finished product of the body 2 is in intimate contact with the first mold 50, and therefore the predetermined tools are caused to advance from the insertion holes to push the abutment surfaces 33 and 34, whereby the semi-finished product of the body 2 is separated from the first mold 50. Then, in the semi-finished product of the body 2 molded as above, there are machined respective screws of the communication hole 18 (temperature-sensing part) which serves holes for mounting the power element 3 on the body 2, the screw hole 31, and the communication hole 13 (adjustment part). Further, by machining a portion for interposing the O ring 23 and the through hole 25, the body 2 is completed.

Next, a simple description will be given of a method of mounting the expansion valve 1. FIG. 6 is a view useful in explaining a state in which the expansion valve 1 has been mounted at the boundary between the vehicle compartment and the engine room. FIG. 7 is a cross-sectional view taken on line B-B of FIG. 6.

As shown in FIG. 6, the expansion valve 1 is fixed to an elliptic hole 82 formed in a partition wall 81 between the vehicle compartment and the engine room, via the fire wall member 83 made e.g. of rubber or sponge. The fire wall member 83 is formed of a hollow cylindrical body having an elliptic outer shape complementary to the hole 82. A square hole 84 is formed in the center of the fire wall member 83 along the outer shape of the expansion valve 1.

In other words, as also shown in FIG. 7, the expansion valve 1 is configured such that it can be fixed to the existing fire wall member 83 by the mounting surfaces 36 (shown hatched for clarity) formed on the body 2. The position of the expansion valve 1 in the front-rear direction thereof is fixed by fitting a flange portion 3a of the power element 3 in a groove 85 formed in the fire wall member 83. It should be noted that pipes, not shown, are connected to the vehicle compartment side of the expansion valve 1 to thereby support the expansion valve 1, and therefore in FIG. 7, there is no fear that the expansion valve 1 is dropped into the vehicle compartment.

Referring again to FIG. 4, in the expansion valve 1 configured as above, the power element 3 senses the pressure and temperature of refrigerant returning from the evaporator and passing through the second passage 9. When the temperature of the refrigerant is high or when the pressure of the refrigerant is low, the valve element 12 is pushed in the valve-opening direction by the shaft 24 to increase the lift of the valve element 12 from the valve seat 10 whereas when the temperature of the refrigerant is low or when the pressure of the refrigerant is high, the valve element 12 is moved in the valve-closing direction to decrease the lift of the valve element 12 from the valve seat 10. Thus, the valve lift of the expansion valve 1 is controlled. On the other hand, liquid refrigerant supplied from the receiver flows through the port 4 into a space where the valve element 12 is located, and passes through the valve section having the valve lift thereof controlled, whereby the liquid refrigerant is throttled and expanded to be changed into low-temperature, low-pressure refrigerant. This refrigerant is delivered from the port 5 and is supplied to the evaporator, where the refrigerant exchanges heat with air in the vehicle compartment, and returns to the port 6 of the expansion valve 1. At this time, the expansion valve 1 controls the flow rate of refrigerant to be supplied to the evaporator such that refrigerant in the outlet of the evaporator has a predetermined degree of superheat, and hence refrigerant is returned from the evaporator to the compressor in a completely evaporated state.

As described above, according to the expansion valve 1, the body 2 is formed by die casting an aluminum alloy, whereby it is possible to easily manufacture the body 2 even when it has a complicated shape with a large number of lightening portions, as in the case of the body 2 according to the present embodiment. Although it is difficult to form lightening portions in side surfaces of the body 2 in directions orthogonal to each other, e.g. by extrusion molding, it is easy to form them by die casting. As a result, it is possible to enhance the degree of freedom of the shape of the body 2, and reduce the weight of the expansion valve 1 to a large extent.

Further, it is possible to easily form component parts, such as the valve section including the valve seat 10 and the valve hole 11, the sealing surfaces formed at the ends of the first passage 8 and the second passage 9, and the mounting surfaces 36 via which the expansion valve 1 is mounted on the fire wall member 83, which are difficult to form by extrusion. Therefore, it is possible to enhance manufacturing efficiency of the body 2.

Furthermore, compared with extrusion and the like, it is possible to largely reduce cutting processes and enhance yield from material, thereby making it possible to reduce the manufacturing costs of the expansion valve 1.

Further, an aluminum alloy is higher in hardness and strength than resin materials, and can be relatively easily plastically deformed. Therefore, it is possible to accurately perform coining of the valve section with ease. As a result, it is possible to positively prevent leakage of refrigerant from the valve section, and reduce flow noises of refrigerant.

It should be noted that although in the present embodiment, the flat surfaces 37 and the mounting surfaces 36 are formed on the body 2 by taking the transfer of the expansion valve 1 and the mounting of the same on a vehicle into account, by way of example, the flat surfaces 37 and the mounting surfaces 36 can be omitted according to how the expansion valve 1 is transferred and how it is mounted.

FIGS. 8A to 10C are views useful in explaining the respective constructions of variations of the expansion valve according to the first embodiment, wherein FIGS. 8A, 9A, and 10A are front views of the variations, FIGS. 8B, 9B, and 10B are left side views of same, and FIGS. 8C, 9C, and 10C are rear views of same. It should be noted that component parts identical to those of the first embodiment will be designated by identical reference numerals.

More specifically, as shown in FIGS. 8A to 8C, the body 2 may be replaced by a body 112 in which the flat surfaces 37 and the mounting surfaces 36 shown on the expansion valve 1 are omitted. Further, as shown in FIGS. 9A to 9C, the body 2 may be replaced by a body 122 in which the mounting surfaces 36 are omitted while leaving the flat surfaces 37 unomitted. Furthermore, as shown in FIGS. 10A to 10C, the body 2 may be replaced by a body 132 in which the flat surfaces 37 are omitted while leaving the mounting surfaces 36 unomitted.

With the above constructions, it is possible to reduce the amount of used aluminum alloy to thereby reduce the manufacturing costs of the expansion valve 1 and further lighten the expansion valve 1.

It should be noted although in the above-described embodiment and variations, the screws of the communication holes 13 and 18 and the screw hole 31 are formed by cutting executed in the last step of manufacturing the body 2, this is not limitative, but the screws as well may be formed integrally with the body 2 by die casting, e.g. using a mandrel having a screw (in this case, the mandrel is removed while being rotated). Further, the portion for interposing the O ring 23 and the through hole 25 may also be formed integrally with the body 2 not by cutting but by die casting. Further, although in FIG. 5, the adjustment part is configured such that it can be formed by inserting the mandrel 70 from below a joining portion where the first mold 50 and the second mold 60 are joined to each other, this is not limitative but another mandrel, for example, may also be inserted from above the joining portion to thereby form the temperature-sensing part as well by die casting.

Further, although in the above-described embodiment and variations, the method of molding the body 2 by the die casting of an aluminum alloy is applied to formation of a temperature expansion valve, by way of example, the method can be applied to formation of an expansion valve of an electromagnetic type or the like. Further, the body 2 can be formed by die casting of a zinc alloy, a magnesium alloy, a copper alloy, or another metal as well as an aluminum alloy.

Further, although in the above-described embodiment and variations, the valve section including the valve seat 10 and the valve hole 11 is formed integrally with the body 2 by die casting, this is not limitative, but to enhance the forming accuracy of the valve section, a finishing process, such as further cutting of the surfaces of the valve section, may be carried out. Even when such a finishing process is performed, since the valve section is substantially formed by die casting, it is possible to obtain the merits described above.

Second Embodiment

Next, a description will be given of a second embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment has a large number of points of construction common to those of the expansion valve according to the first embodiment, and hence component parts approximately identical to those of the first embodiment will be designated by identical reference numerals, and description thereof is omitted. FIG. 11 is a front view of the expansion valve. FIG. 12 is a left side view of the same. FIG. 13 is a rear view of the same. Further, FIG. 14 is a cross-sectional view taken on line C-C of FIG. 11.

Referring to FIGS. 11 to 13, the expansion valve 201 has a body 202 formed by die casting an aluminum alloy. The body 202 as well is generally prism-shaped, and has lightening portions for reducing the weight thereof formed all over its side surfaces.

As shown in FIG. 14, in the expansion valve 201, the ball-shaped valve element 12 is supported by a valve element receiver 216. A spring receiver 215 having an annular groove in a foremost end face thereof is fitted on a foremost end of an adjustment screw 214 which is provided in a manner sealing the communication hole 13 of the body 202, and the helical compression spring 16 is interposed between the spring receiver 215 and the valve element receiver 216. The helical compression spring 16 has the valve element receiver 216 inserted into one end thereof, and the other end thereof inserted into a groove of the spring receiver 215, for urging the valve element 12 via the valve element receiver 216 in the direction in which the valve element 12 is seated on the valve seat 10. Similarly to the case of the first embodiment, the adjustment screw 214 is configured such that it can adjust the load of the helical compression spring 16 by adjusting the screwing amount thereof into the body 202.

Further, an upper portion of the shaft 24 is held by a holder 227 disposed in a manner crossing the second passage 9. A coil spring 217 for urging the shaft 24 from the lateral direction is disposed at an upper portion of the holder 227. The expansion valve 201 is configured such that lateral load is applied to the shaft 24 by the coil spring 217, whereby when high-pressure refrigerant in the port 4 undergoes a change in pressure, the axial motion of the shaft 24 is inhibited from sensitively reacting to the change. In short, the coil spring 217 forms a vibration suppressing mechanism for suppressing generation of untoward vibration noise caused by vibrations of the shaft 24 in the axial direction.

Furthermore, a disk 222 of a power element 203 has a disk-shaped body formed by forging an aluminum material such that an upper half of the disk 222 radially outwardly extends to form a flange portion 223. The flange portion 223 has a lower end face formed with communication grooves, not shown, radially extending in radial directions such that refrigerant having flowed in from the second passage 9 through the communication hole 18 is allowed to pass therethrough and be guided to the lower surface of the diaphragm 21 inside the lower housing 20. An engaging protrusion 224 protrudes from the center of the lower surface of the disk 222 such that it is in abutment with an upper end of the shaft 24 to be united therewith, while being guided by an engaging groove 227a formed in the upper end of the holder 227. A root portion of the engaging protrusion 224 is brought into engagement with an upper end face of the holder 227 to define the bottom dead center of the disk 222. Further, a pad 225 is disposed on a surface of the diaphragm 21 opposite from the disk 222 (on the temperature sensing chamber side) such that liquid contents can be held even when the temperature-sensing gas is condensed to form the liquid contents.

Further, as shown in FIGS. 11 to 13, similarly to the first embodiment, the body 202 has mounting surfaces 236 and flat surfaces 237 formed on left and right side surfaces thereof. Further, on a side surface of the body 202 where the port 4 opens, an ear-shaped inflated portion 239 is formed in a manner extending from the opening of the port 4. The inflated portion 239 is formed at the same time when the body 202 is formed by die casting, and has a foremost end thereof extending more outwardly than a side surface on one side parallel to the first passage 8 of the body 202. The foremost end of the inflated portion 239 is formed with a screw hole 240 (through hole) into which a fastening bolt is screwed when a joint for a pipe connected to a receiver, not shown, is connected to the port 4.

Furthermore, the body 202 has a plurality of lightening portions in its side surfaces. More specifically, the lightening portions 241 are formed in portions of the left and right side surfaces of the body 202, except for portions formed with the mounting surfaces 236 and the flat surfaces 237, further in portions of side surfaces of the body 202 orthogonal to these faces 236 and 237, except for the rims of the first passage 8, the second passage 9, and the screw hole 31, and the inflated portion 239. Even the lightening portions having the above-described relatively complicated shapes can be easily formed by die casting.

It should be noted that the expansion valve 201 is manufactured by die casting an aluminum alloy, similarly to the first embodiment. In manufacturing the expansion valve 201, the die casting is executed using a mold having approximately the same construction as that of the mold shown in FIG. 5 though the shapes of the chambers are different, and the same aluminum alloy as used in the first embodiment is used. Therefore, a description of the manufacturing method of the expansion valve 201 is omitted.

As described hereinabove, also in the expansion valve 201, the body 202 is formed by die casting an aluminum alloy. This makes it possible to easily manufacture the body 202, even when the body 202 has a large number of lightening portions in outer surfaces thereof, and the internal shape of the body 202 is complicated. Further, since cutting processes can be largely reduced, it is possible to reduce the manufacturing costs of the expansion valve 201. Further, the whole weight of the body 202 can be reduced.

Third Embodiment

Next, a description will be given of a third embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment has approximately the same construction as that of the expansion valve according to the second embodiment, except that the shape of the body is different, and hence component parts approximately identical to those of the second embodiment will be designated by identical reference numerals, and description thereof is omitted. FIG. 15 is a front view of the expansion valve. FIG. 16 is a left side view of the same. FIG. 17 is a right side view of the same. FIG. 18 is a rear view of the same. Further, FIG. 19 is a cross-sectional view taken on line D-D of FIG. 15.

Referring to FIGS. 15 to 18, the expansion valve 301 has a body 302 formed by die casting an aluminum alloy. Although the body 302 is also generally prism-shaped, it has ear-shaped inflated portions 331 and 332 extending from openings of the ports 4 and 7 formed in side surfaces of the body 302. The inflated portions 331 and 332 are formed at the same time when the body 302 is formed by die casting, such that foremost ends thereof extending more outwardly than side surfaces on one side parallel to the first passage 8 and the second passage 9 of the body 302, respectively. The foremost end of the inflated portion 331 is formed with a screw hole 333 (through hole) into which a fastening bolt is screwed when a joint for a pipe connected to a receiver, not shown, is connected to the port 4. Further, an insertion hole 334 for inserting a positioning pin when the joint is connected is formed adjacent to the screw hole 333. Further, the foremost end of the inflated portion 332 is formed with a screw hole 335 into which a fastening bolt is screwed when a joint for a pipe connected to a compressor, not shown, is connected to the port 7. Further, an insertion hole 336 for inserting a positioning pin when the joint is connected is formed adjacent to the screw hole 335. Further, as shown in FIG. 19, the expansion valve 301 has approximately the same internal construction as that of the expansion valve 201 according to the second embodiment.

Further, as shown in FIGS. 15 to 18, the body 302 as well has mounting surfaces 338 and flat surfaces 339 formed on left and right side surfaces. Furthermore, the body 302 has a plurality of lightening portions formed in side surfaces thereof. More specifically, the lightening portions 341 are formed in portions of the left and right side surfaces of the body 302, except for portions formed with the mounting surfaces 338 and the flat surfaces 339, further in portions of side surfaces of the body 302 orthogonal to these faces 338 and 339, except for the respective rims of the first passage 8, the second passage 9, and the screw hole 31, and the outer peripheries of the inflated portions 331 and 332. Even such lightening portions having relatively complicated shapes, as described above, can be easily formed by die casting.

It should be noted that the expansion valve 301 is manufactured by die casting an aluminum alloy, similarly to the first embodiment, and the same aluminum alloy as used in the first embodiment is used. Therefore, here, a description of the manufacturing method of the expansion valve 301 is omitted.

As described above, since the body 302 is formed by die casting an aluminum alloy, the expansion valve 301 can also be easily manufactured even though it has a complicated shape having the inflated portions 331 and 332, as shown in FIGS. 15 to 18, at low costs. Furthermore, the whole weight of the body can be reduced.

FIGS. 20A to 20D are views useful in explaining the construction of a variation of the expansion valve according to the third embodiment, wherein FIG. 20A is a front view of the expansion valve. FIG. 20B is a left side view of the same. FIG. 20C is a right side view of the same. FIG. 20D is a rear view of the same. It should be noted that component parts identical to those of the above-described embodiments will be designated by identical reference numerals.

More specifically, in the present variation, a body 322 formed by die casting of an aluminum alloy is formed with almost no lightening portions 341. Although the body 322 is generally prism-shaped, it has an ear-shaped inflated portion 351 formed along a side surface thereof where the ports 4 and 7 open, in a manner extending from the side surface at right angles thereto. The inflated portion 351 has a screw hole 333 and an insertion hole 334 formed in the vicinity of the port 4, and a screw hole 335 and an insertion hole 336 formed in the vicinity of the port 7. Further, formed around the pair of dummy holes 32 arranged in the side surface are countersinks 325 for accommodating the heads of bolts inserted into the dummy holes 32.

Fourth Embodiment

Next, a description will be given of a fourth embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment has a large number of points of construction common to the expansion valve according to the second embodiment, except that it is configured such that the first and second passages are bent inside the body. Therefore, component parts approximately identical to those of the second embodiment will be designated by identical reference numerals, and description thereof is omitted. FIG. 21 is a perspective view of the expansion valve according to the fourth embodiment. FIG. 22 is a front view of the same. FIG. 23 is a left side view of the same. Further, FIG. 24 is a cross-sectional view taken on line E-E of FIG. 22, and FIG. 25 is a cross-sectional view taken on line F-F of FIG. 23.

Referring to FIGS. 21 to 23, in a body 402 of an expansion valve 401, a portion of a passage where the port 4 is located and a portion of a passage where the port 5 is located cross each other, while a portion of a passage where the port 6 is located and a portion of a passage where the port 7 is located cross each other, and the ports 5 and 6 open in a side surface adjacent to a side surface where the ports 4 and 7 open. That is, the body 402 is configured such that the first passage 408 and the second passage 409 in the first embodiment are bent through 90 degrees inside the body 402, and the pipes connected to the receiver and the compressor, not shown, respectively, are connected to the expansion valve 401, at an angle 90 degrees shifted from the direction of the pipe connected to the evaporator. Lightening portions 441 are formed at a plurality of locations, such as around the ports, in the surface of the body 402 formed by die casting of an aluminum alloy.

As shown in FIGS. 24 and 25, a first passage 408 and a second passage 409 bend through 90 degrees in the center of the body 402. As a result, refrigerant introduced from the receiver, not shown, into the port 4 is turned through 90 degrees within the body 402 and delivered from the port 5, while refrigerant introduced into the port 6 after being returned from the evaporator is turned through 90 degrees within the body 402 and delivered from the port 7.

Next, a description will be given of essentials of a method of manufacturing the expansion valve according to the present embodiment. FIG. 26 is a view useful in explaining the outline of the essentials of the method of manufacturing the expansion valve. It should be noted that for convenience of description, component parts identical to those illustrated in FIG. 5 will be designated by identical reference numerals, and description thereof is omitted.

The expansion valve 401 is manufactured by die casting of an aluminum alloy having the same composition as that of the aluminum alloy used in the first embodiment. In the present embodiment, an apparatus comprised of a first mold 450, a second mold 460, a mandrel 70, and mandrels 471 to 473, as illustrated in FIG. 26, is employed. The main body and chambers forming refrigerant passages and the like of the body 402 are formed by the first mold 450, the second mold 460, the mandrels 70 and 471 to 473.

The first mold 450 has a chamber 451 for forming the left half of the body 402. Within the chamber 451, port-forming portions 452 and 453 for forming the ports 5 and 6, respectively, and the dummy hole-forming portions 55 for forming the dummy holes 32 protrude toward the opening on the rear side. Further, the mandrel inserting portion-forming groove 56 and an injection passage-forming groove 457 are formed in the rear surface of the first mold 450 in a manner communicating with the chamber 451.

Further, mandrel inserting portion-forming grooves 481, 482, and 483 for forming insertion holes for inserting the mandrels 471, 472, and 473 from a side, respectively, are formed in the rear surface of the first mold 450 in a manner communicating with the chamber 451, respectively. The mandrel 471 is provided for forming the port 4, the mandrel 472 for forming a pilot hole of the screw hole 31, and the mandrel 473 for forming the port 7. The mandrel inserting portion-forming grooves 481, 482, and 483 extend in a direction approximately at right angles to the port-forming portions 452 and 453.

On the other hand, the second mold 460 has a chamber 461 for molding the right half of the body 402. Within the chamber 461, a port-forming portion 462 for forming the port 5 in cooperation with the port-forming portion 452, and a port-forming portion 463 for forming the port 6 in cooperation with the port-forming portion 453 protrude toward the opening. Further, mandrel inserting portion-forming grooves 491, 492, and 493 for forming the insertion holes for inserting the mandrels 471, 472, and 473 are formed in the front surface of the second mold 460 in a manner opposed to the mandrel inserting portion-forming grooves 481, 482, and 483, such that the mandrel inserting portion-forming grooves 491, 492, and 493 communicate with the chamber 451. The mandrel inserting portion-forming grooves 491, 492, and 493 extend in a direction approximately at right angles to the port-forming portions 462 and 463. Furthermore, the mandrel inserting portion-forming groove 64 for forming an insertion hole for inserting the mandrel 70 in cooperation with the mandrel inserting portion-forming groove 56, and an injection passage-forming groove 465 for forming an injection passage in cooperation with the injection passage-forming groove 457 are formed in the front surface of the second mold 460 in a manner communicating with the chamber 451, respectively.

In manufacturing the body 402, a molten aluminum alloy is injected from the injection passage in a state in which the first mold 450, the second mold 460, and the mandrels 70 and 471 to 473 are assembled with each other, thereby performing die casting. After the aluminum alloy hardens, the mandrels 70 and 471 to 473 are removed and then the first mold 450 and the second mold 460 are separated from each other.

Fifth Embodiment

Next, a description will be given of a fifth embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment has the same construction as that of the expansion valve according to the first embodiment, except that the shape of the first passage is different, and hence component parts identical to those of the first embodiment will be designated by identical reference numerals, and description thereof is omitted. FIG. 27 is a rear view of the expansion valve according to the fifth embodiment. FIG. 28 is a cross-sectional view taken on line G-G of FIG. 27.

As shown in FIGS. 27 and 28, in a body 502 of the expansion valve 501, a passage 510 having a not circular but wave-shaped pipe wall is formed on the outlet side of the valve hole 11 of a first passage 508, that is, on the side toward the port 5. Even such a complicated shape can be easily realized by die casting an aluminum alloy. To manufacture the expansion valve 501 constructed as above, it is only required that the port-forming portion 62 of the second mold 60 appearing in FIG. 5 is configured to be partially wave-shaped in cross section, for example. Description of the method of manufacturing the expansion valve 501 is omitted.

It should be noted the shape of the pipe wall is by no means limited to the above-mentioned wave shape, but the pipe wall can have various shapes. FIG. 29 is a cross-sectional view of a variation of the present embodiment. It should be noted that in the figure, component parts identical to those of the expansion valve according to the first embodiment will be designated by identical reference numerals.

In a body 522 of an expansion valve 521, a passage 520 having a smooth pipe wall with a curved surface is formed on the outlet side of the valve hole 11 of a first passage 528. The passage 520 is progressively expanded in cross section from the valve hole 11 side toward the port 5 side. Even such a shape can be easily realized by die casting of an aluminum alloy.

Sixth Embodiment

Next, a description will be given of a sixth embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment has approximately the same construction as that of the expansion valve according to the first embodiment, except that a bolt and a valve seat-forming portion separately prepared are integrally assembled to a body. Therefore, component parts identical to those of the first embodiment will be designated by identical reference numerals, and description thereof is omitted. FIG. 30 is a cross-sectional view of the expansion valve according to the sixth embodiment.

In a body 602 of the expansion valve 601, a stud bolt 630 is formed by insert molding at a portion corresponding to the screw hole 31 appearing in FIG. 4. The stud bolt 630 is for fixing a fixed plate, not shown, for connecting pipes connected to a compressor and a receiver to the associated ports, when the fixed plate is attached to the body 602. It should be noted that in FIG. 30, for clarity, the stud bolt 630 is shown in side view not in cross section so as to enable the shape of the stud bolt 630 to be easily understood. The stud bolt 630 is configured such that one end thereof is formed with a knurl 631, and a portion thereof exposed from the body 602 to the outside is formed with a male thread 632. The stud bolt 630 is formed in advance before manufacturing the expansion valve 601.

Further, in the body 602 as well, a valve seat-forming member 606 for forming a valve seat is formed by insert molding, between an introduction passage 604 for introducing refrigerant to the upstream side of the valve section in the first passage 8 and a delivery passage 605 for delivering refrigerant from the downstream side of the valve section. It should be noted that the introduction passage 604 and the delivery passage 605 are arranged in a manner extending along axes different from each other, as shown in FIG. 30, and the valve hole 11 is formed to be orthogonal to the passages 604 and 605 for connection therebetween. The valve seat-forming member 606 has an annular shape, and the valve hole 11 is formed in a manner extending through the center of the valve seat-forming member 606. The lower half of the valve hole 11 of the valve seat-forming member 606 is formed with a tapered portion the outer diameter of which is expanded toward a lower end of the valve hole 11, and the valve seat 10 for having the valve element 12 seated thereon is formed by the tapered face of the tapered portion. The valve seat-forming member 606 as well is formed in advance before manufacturing the expansion valve 601.

When the body 602 is formed by die casting an aluminum alloy, the stud bolt 630 and the valve seat-forming member 606 are arranged in advance at predetermined locations of the molds, for insert molding thereof in the body 602.

As described above, when the body 602 is formed by die casting, structures, such as the stud bolt 630 and the valve seat-forming member 606 separately prepared as required, are insert-molded, whereby it is possible to easily assemble portions difficult to form by die casting alone, portions demanding accuracy, and portions made of materials different from that of the body 602 (e.g. portions demanding large strength), to the body 602. Further, it is not necessary to form a screw hole for fixing the stud bolt to the body 602 or the like, either.

It should be noted that although in the present embodiment, to prevent the stud bolt 630 from rotating about its axis after being insert-molded in the body 602, the construction is shown in which the knurl 631 having a jagged shape is formed in an inserting portion of the stud bolt 630, this is not limitative, but the inserting portion can be configured to have another rotation-preventing shape, such as a polygonal shape.

Further, although a valve seat-forming member having the valve hole 11 formed therein in advance is shown as the valve seat-forming member 606, by way of example, a disk-shaped member having no valve hole 11 formed therein may be insert-molded when the body 602 is formed by die casting, and thereafter the valve hole 11 may be formed in the member.

Further, although in the present embodiment, an example of the construction is shown in which the introduction passage 604 and the delivery passage 605 are arranged in a manner extending along the axes different from each other, and connected to each other by the valve hole 11 formed to be orthogonal to the passages 604 and 605, that is not limitative but insofar as the valve hole is disposed between the introduction passage and the delivery passage, for connecting therebetween, various constructions other than the illustrated example can be employed. For example, the introduction passage and the delivery passage may be configured such that the axis of at least one of them deviates in the vicinity of the valve section, and they are arranged on different axes in the vicinity of the valve section, but are arranged on the same axis in the vicinity of their openings where they open to the outside. Further, it is not necessary for the valve hole to be orthogonal to each of the introduction passage and the delivery passage, but the valve hole is only required to have respective opposite ends thereof connected to the passages.

Seventh Embodiment

Next, a description will be given of a seventh embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment has the same construction as that of the expansion valve according to the first embodiment, except that the manner of mounting the expansion valve is different. Therefore, component parts identical to those of the first embodiment will be designated by identical reference numerals, and description thereof is omitted. FIG. 31 is a left side view of the expansion valve according to the seventh embodiment. FIG. 32 is a view useful in explaining a state in which the expansion valve has been mounted at the boundary between the vehicle compartment and the engine room. Further, FIG. 33 is a cross-sectional view taken on line H-H of FIG. 32.

As shown in FIG. 31, the expansion valve 701 is formed with a mounting surface 736 via which the expansion valve 701 is mounted on a fire wall member, described hereinafter, provided at the boundary between the vehicle compartment and the engine room, and flat surfaces 737 used as holders when the expansion valve 701 is carried by a predetermined apparatus. In the present embodiment, the mounting surface 736 is formed not in the center of the body 702 but at the front end of the body 702 in the front-rear direction thereof, i.e. along the outer peripheral surface of the engine room-side end of the body 702. At the location of the front end of the body 702, there is circumferentially formed a flange portion 703 extending outward from the body 702 along the outer periphery thereof. The body 702 including the lightening portions 41 formed in the side surfaces of the body 802, is integrally formed by die casting of an aluminum alloy.

Referring to FIG. 32, the expansion valve 701 is fixed to the elliptic hole 82 formed in the partition wall 81 between the vehicle compartment and the engine room, via a fire wall member 783 made e.g. of rubber or sponge. The fire wall member 783 is formed of a hollow cylindrical body having an elliptic outer shape complementary to the hole 82. A supporting hole 784 is formed in the center of the fire wall member 783 along the outer shape of a front end of the expansion valve 701.

As also shown in FIG. 33, the expansion valve 701 is configured such that it can be rigidly fixed to the fire wall member 783 by the mounting surface 736 (shown hatched for clarity) formed on the body 702. The expansion valve 701 is rigidly fixed to the fire wall member 783 by the flange portion 3a of the power element 3 and the flange portion 703 such that the fire wall member 783 is held therebetween. Therefore, approximately the whole expansion valve 701 is disposed within the vehicle compartment.

As described above, the mounting surface 736 is formed on an end of the body 702 and the expansion valve 701 is fixed in a manner sandwiching the fire wall member 783. This makes it possible to form the fire wall member 783 compact in size.

Eighth Embodiment

Next, a description will be given of an eighth embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment is configured similarly to the expansion valve according to the first embodiment, except that the manner of mounting the expansion valve is different. Therefore, component parts identical to those of the first embodiment will be designated by identical reference numerals, and description thereof is omitted. FIG. 34 is a left side view of the expansion valve according to the eighth embodiment. FIG. 35 is a view useful in explaining a state of the expansion valve in which it is mounted at the boundary between the vehicle compartment and the engine room. Further, FIG. 36 is a cross-sectional view taken on line I-I of FIG. 35.

In the present embodiment, as is distinct from the above-described seventh embodiment, the expansion valve is disposed not within the vehicle compartment but on the engine room side.

More specifically, as shown in FIG. 34, the expansion valve 801 is formed with a mounting surface 836 via which the expansion valve 801 is mounted on a fire wall member, described hereinafter, disposed on the boundary between the vehicle compartment and the engine room, and a flat surface 837 used as holders when the expansion valve 801 is carried by a predetermined apparatus. In the present embodiment, the mounting surface 836 is formed at the rear end of the body 802 in the front-rear direction thereof, i.e. along the outer peripheral surface of the compartment-side end of the body 802. At the location of the rear end of the body 802, there is circumferentially formed a flange portion 803 extending outward from the body 802 along the outer periphery thereof. The body 802 including the lightening portions 41 formed in the side surfaces of the body 802 is integrally formed by die casting of an aluminum alloy.

Referring to FIG. 35, the expansion valve 801 is fixed to the elliptic hole 82 formed in the partition wall 81 between the vehicle compartment and the engine room, via a fire wall member 883 made e.g. of rubber or sponge. The fire wall member 883 is formed of a hollow cylindrical body having an elliptic outer shape complementary to the hole 82. A supporting hole 884 is formed in the center of the fire wall member 883 along the outer shape of a rear end of the expansion valve 801.

As also shown in FIG. 36, the expansion valve 801 is configured such that it can be rigidly fixed to the fire wall member 883 by the mounting surface 836 (shown hatched for clarity) formed on the body 802. The expansion valve 801 is rigidly fixed to the fire wall member 883 by the flange portion 3a of the power element 3 and the flange portion 803 which hold the fire wall member 883 therebetween. Therefore, approximately the whole expansion valve 801 is disposed within the vehicle compartment.

Ninth Embodiment

Next, a description will be given of a ninth embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment is constructed approximately similarly to the expansion valve according to the third embodiment, except that a body thereof is formed with a pin for positioning a joint for a pipe. Therefore, component parts identical to those of the third embodiment will be designated by identical reference numerals, and description thereof is omitted. FIGS. 37A and 37B are views useful in explaining the construction of the body of the expansion valve according to the ninth embodiment, wherein FIG. 37A is a left side view of the body, and FIG. 37B is a front view of the same. It should be noted that for clarity, the body alone is shown, but the power element and the internal construction are omitted.

The expansion valve 901 has the body 902 formed by die casting of an aluminum alloy. A cylindrical pin 903 protrudes from the inflated portion 332 extending from the body 902. The pin 903 is formed simultaneously with the inflated portion 332 and the like when the body 902 is formed by die casting. When a pipe connected to a receiver, not shown, is connected to the associated port, the pin 903 is used for positioning a joint for the pipe, which is interposed between the body and the pipe.

The expansion valve 901 is manufactured by die casting of an aluminum alloy, similarly to the first embodiment, and the same aluminum alloy as used in the first embodiment is used. Therefore, here, a description of the manufacturing method of the expansion valve 901 is omitted.

It should be noted that although in the present embodiment, a construction is shown in which one joint-positioning pin 903 is formed on the inflated portion 332, two or more pins 903 may be formed. Alternatively, the pin(s) may be formed on the inflated portion 331 or at portions of the body 902 different from the inflated portions 331 and 332.

As described above, in the present embodiment, the expansion valve is configured such that the joint-positioning pin 903 is formed integrally with the body 902 by die casting. This makes it possible to reduce man-hours for manufacturing the expansion valve compared with the conventional manufacturing process in which the joint-positioning pin is formed after molding the body, and dispense with cumbersome operations for assembling the pin to the body.

Tenth Embodiment

Next, a description will be given of a tenth embodiment of the present invention. It should be noted that an expansion valve according to the present embodiment has approximately the same construction as that of the expansion valve according to the first embodiment, except that a refrigerant leakage passage is formed in the body. Therefore, component parts identical to those of the first embodiment will be designated by identical reference numerals, and description thereof is omitted. FIG. 38 is a central longitudinal cross-sectional view of an expansion valve according to the tenth embodiment, which corresponds to FIG. 4. FIGS. 39A to 39C are views useful in explaining the configuration of a valve section and its vicinity of the body, wherein FIG. 39A is a fragmentary cross-sectional view of the valve section and its vicinity of the body, FIG. 39B an end view of the FIG. 39A expansion valve, as viewed from below, and FIG. 39C a view useful in explaining a closed state of the valve section and associated component parts.

Referring to FIG. 38, a bleed hole 1003 (corresponding to “the refrigerant leakage passage”) is formed to extend through the vicinity of the valve hole 11 in the body 1002 of the expansion valve 1001 in parallel with the valve hole 11.

As shown in FIGS. 39A and 39B, the bleed hole 1003 is a circular hole having a considerably smaller cross section than that of the valve hole 11. Further, as shown in FIG. 39C, the expansion valve 1001 is configured such that even when the valve element 12 is seated on the valve seat 10 to close the valve hole 11, in the closed state of the valve section, it is possible to ensure a flow of refrigerant flowing through the bleed hole 1003 at a predetermined flow rate from the upstream side to the downstream side. This makes it possible to circulate a minimum amount of lubricating oil contained in the refrigerant, thereby making it possible to increase the amount of return of oil to the compressor. Further, when the expansion valve 1001 is used in a dual air conditioner-mounting vehicle, which has air conditioners arranged in the front part and the rear of the vehicle, it is possible to prevent refrigerant from becoming stagnant in an evaporator in the rear part of the vehicle.

The expansion valve 1001 is manufactured by die casting of an aluminum alloy, similarly to the first embodiment, and the same aluminum alloy as used in the first embodiment is used. The bleed hole 1003 as well is formed at the same time when the body 1002 is integrally formed.

More specifically, the formation of the bleed hole 1003 can be achieved by forming a pin therefor on the mandrel 70 illustrated in FIG. 5. Here, illustration thereof is omitted.

As described above, in the present embodiment, the expansion valve 1001 is configured such that the bleed hole 1003 as a part of the refrigerant leakage passage used when the valve section is closed is formed integrally with the body 1002 by die casting. This makes it possible to reduce man-hours for manufacturing the expansion valve compared with the conventional manufacturing process in which the bleed hole is formed by cutting after molding the body.

FIGS. 40A to 40C are views useful in explaining the construction of a first variation of an expansion valve according to the tenth embodiment. The figures show the construction of a valve section and its vicinity of the body, and correspond to FIGS. 39A to 39C.

In this variation, nicked seat portions are formed as refrigerant leakage passages in the valve section itself. More specifically, as shown in FIGS. 40A and 40B, three nicked seat portions 1023 comprised of grooves formed in a manner continuous with the valve hole 11 are formed in the valve seat 1010 of the body 1022 at circumferentially predetermined spaced intervals (of 120 degrees). Thus, as shown in FIG. 40C, even when the valve element 12 is seated on the valve seat 1010, gaps are formed between the nicked seat portions 1023 and the valve element 12, for communication with the valve hole 11. As a result, also when the valve section is closed, it is possible to ensure a flow of refrigerant flowing at a predetermined flow rate from the upstream side to the downstream side, thereby making it possible to obtain the same advantageous effects as provided by the bleed hole 1003 of the tenth embodiment.

FIGS. 41A to 41C are views useful in explaining a second variation of the expansion valve according to the tenth embodiment. The figures show the construction of a valve section and its vicinity of the body, and correspond to FIGS. 39A to 39C.

In this variation, nicked seat portions are formed as refrigerant leakage passages in the valve section itself. More specifically, as shown in FIGS. 41A and 41B, three nicked seat portions 1033 comprised of grooves are formed in the valve hole 1031 of the body 1032 at circumferentially predetermined spaced intervals (of 120 degrees). Therefore, as shown in FIG. 41C, even when the valve element 12 is seated on a valve seat 1030 in the closed state of the valve section, gaps are formed between the nicked seat portions 1033 and the valve element 12, for communication with the valve hole 1031. As a result, also when the valve section is closed, it is possible to ensure a flow of refrigerant flowing at a predetermined flow rate from the upstream side to the downstream side, thereby making it possible to obtain the same advantageous effects as provided by the bleed hole 1003 according to the tenth embodiment.

As described above, the nicked seat portions 1023 and 1033 in the first and second variations are formed at the same time when the bodies 1022 and 1032 are formed as respective integral bodies by die casting.

More specifically, the formation of the nicked seat portions 1023 and 1033 can be achieved by forming projections for forming the nicked seat portions on the mandrel 70 illustrated in FIG. 5. Here, illustration thereof is omitted.

As described above, in the respective variations, the nicked seat portions of the valve sections are formed integrally with the bodies by die casting. Although conventionally, it has been difficult to manufacture nicked seat portions stable in size, since the nicked seat portions are formed by punching after a body is formed, according to the above die casting, it is possible to easily perform accurate machining of nicked seat portions by mold machining.

Although the preferred embodiments according to the present invention and variations thereof have been described heretofore, the present invention is by no means limited to the specific embodiments and the like, but various modifications and alterations can be made thereto without departing from the spirit and scope of the present invention.

Although in the above embodiments, no particular descriptions have been given, it is important to cope with the problem of so-called “gross porosity”, when the bodies of the expansion valves are formed by die casting a metal.

More specifically, when a liquid molten metal (aluminum alloy in each embodiment described above) is injected into the mold of a body, the molten metal is caused to flow into the mold through the injection passage at high speed and high pressure. As a result, air is entrained into the molten metal passing through the injection passage, or by a turbulent flow generated by the molten metal passing through component part-forming portions of the mold, whereby air pores (gross porosity formed by entrained air) are sometimes produced inside the body.

Further, the molten metal starts to solidify from low-temperature contact surfaces thereof inside the mold, and thick portions of the metal are the last to solidify. Shrinkage of the portions that solidify at the last stage can produce shrinkage cavities. Further, the body formed as above sometimes has uneven crystalline particles with many dendritic structures, and the dendritic structures can be start points of fracture.

If many or large cavities are formed in the body, there is a fear that adjacent cavities are connected to each other to cause refrigerant to leak from the body, or leak from between internal passages.

Therefore, to make the above cavities difficult to form, it is preferable to employ a semi-solid die casting process for molding the body.

In this method, die casting is carried out by injecting not a liquid metal slurry but a semi-solid metal slurry into the mold of the body (see FIGS. 5 and 26). The semi-solid metal slurry has many spherical particle structures with few dendritic structures. Further, since solid structures already exist, the ratio of molten metal portion per unit area is small, and therefore shrinkage cavities are more difficult to form than in the case where liquid molten metal is used. Further, since the metal slurry is filled in the mold in the semi-solid state thereof, a turbulent flow thereof scarcely occurs in the mold. This makes it difficult to form cavities by entrained air.

More specifically, it is envisaged to employ a semi-solid die casting process disclosed e.g. in the publication of Japanese Patent No. 3496833.

That is, at the stage of making a metal slurry, a molten metal is poured and agitated in a predetermined container with an electromagnetic field applied thereto, whereby spherical particles are formed without forming almost no dendritic crystals. Then, at a time point the solid phase ratio of the molten metal becomes preferably not less than 0.001 and not more than 0.1, the application of the electromagnetic field is terminated, and the molten metal is cooled. Then, at a time point the solid phase ratio of the molten metal becomes preferably not less than 0.1 and not more than 0.7, the cooling of the molten metal is terminated, whereby the metal slurry in a solid-liquid coexistent state is obtained. It should be noted that to make it easy to form a solid-liquid coexistent state of a metal slurry, it is preferable to use an aluminum alloy having a composition which contains not more than 17.0 wt % of Si, preferably 6.5 to 12.0 wt % of Si. For example, it is possible to use an aluminum alloy containing 9.6 to 12.0 wt % of Si as described above concerning the first embodiment, or an aluminum alloy containing 6.5 to 7.5 wt % of Si proven as a semi-solid material.

The metal slurry formed as described above is composed of fine spherical particles having an average particle diameter of not less than 10 μm and not more than 60 μm with a uniform particle size distribution. It is considered that this is because heat transmission within the molten metal is fast to suppress formation of an initial solid layer on the inner wall of the container, since the electromagnetic field is applied to the container when the molten metal is poured into the container, and inner molten metal and surface molten metal are well agitated. Therefore, uniform spherical particles are formed without forming almost no dendritic crystals.

There is no need to limit the semi-solid die casting process employed for molding the body to the process disclosed in the publication of Japanese Patent No. 3496833. For example, it is possible to employ other semi-solid die casting processes, such as a rheocasting process and a thixocasting process. However, the semi-solid die casting process disclosed in the publication of Japanese Patent No. 3496833 is preferable because the method is particularly excellent in suppressing generation of gross porosity since the process makes it possible to obtain a metal slurry with a smaller average particle diameter than a semi-solid die casting process of a general type.

As described heretofore, by employing the semi-solid die casting process for molding the body, it is possible to suppress generation of cavities by entrained air, shrinkage cavities, and the like, thereby making it possible to achieve high hermeticity, high strength, high toughness, and high resistance properties. Further, a metal slurry has a lower temperature than that of a molten metal, which makes it possible to reduce thermal load on a mold to increase the service life of the mold.

According to the expansion valve of the present invention, a body is formed by die casting a metal, and hence it is possible to easily manufacture the body even when it has such a complicated shape that includes a large number of lightening portions. Further, since the valve seat which is difficult to form by extrusion can be formed substantially integrally with the body, it is possible to enhance the manufacturing efficiency of the body. Furthermore, portions, such as the valve seat, conventionally formed by cutting, can be formed integrally with the body by die casting. Therefore, it is possible to enhance yield from material, thereby making it possible to reduce manufacturing costs of the expansion valve.

Also, according to another expansion valve of the present invention, the body is formed by die casting a metal. Therefore, the expansion valve can be easily manufactured even if the body has a complicated shape.

The foregoing is considered as illustrative only of the principles of the present invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and applications shown and described, and accordingly, all suitable modifications and equivalents may be regarded as falling within the scope of the invention in the appended claims and their equivalents.

Number	Date	Country	Kind
2006-012969	Jan 2006	JP	national
2005-356373	Dec 2005	JP	national
2005-212618	Jul 2005	JP	national
2005-060795	Mar 2005	JP	national

Expansion valve

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Priority Claims (4)