KR20180085352A - Expansion valve - Google Patents

Abstract

The present invention relates to an expansion valve, wherein control hunting is prevented and efficient function is secured with low cost. An embodiment of the present invention provides an expansion valve including: a body (2) having a second passage (14) through which refrigerant returning from an evaporator passes and a mount hole (50) communicating with the second passage (14); a power element (3) mounted on the body (2) so as to cover the mount hole (50); a shaft (33) transferring a driving force of the power element (3) to a valve body (18); and a plate (31) being spaced apart from an open space (S2) and the second passage (14) and having an insertion hole (36) provided along a central axis of the shaft so as to have the same axis as the shaft so as to insert and pass the shaft (33), the plate restricting the introduction of refrigerant to the open space (S2) from the second passage (14) to a gap between the insertion hole (36) and the shaft (33), wherein the area of an opening defined by the gap between the insertion hole (36) and the shaft (33) is 7.0mm^2 or less.

Description

Expansion Valve {EXPANSION VALVE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion valve, and more particularly to a thermally-assisted expansion valve suitable for a refrigeration cycle.

The refrigeration cycle of the air conditioner for an automobile generally includes a compressor for compressing the circulating refrigerant, a condenser for condensing the compressed refrigerant, an expansion valve for throttling the condensed refrigerant, An evaporator for cooling is provided. As the expansion valve, for example, the temperature and the pressure of the refrigerant at the outlet side of the evaporator are sensed to adjust the valve opening degree so that the refrigerant led out from the evaporator has a predetermined degree of superheat, and the flow rate of the refrigerant to be sent to the evaporator is controlled A thermostatic expansion valve is used (for example, see Patent Document 1).

In the body of such an expansion valve, a first passage through which the refrigerant from the condenser to the evaporator passes, and a second passage through which the refrigerant returned from the evaporator is passed. A valve hole is formed in the first passage, and a valve body is disposed so as to face the valve hole. The valve body aligns with the valve hole to adjust the flow rate of the refrigerant toward the evaporator. Further, a mounting hole is provided at one end of the body, and is communicated with the second passage through the communication hole. A power element is mounted in this mounting hole. The power element operates by sensing the temperature and pressure of the refrigerant flowing through the second passage, and the driving force is transmitted to the valve body through the shaft. The shaft passes through the partition of the first passage and the second passage, one end is connected to the power element, and the other end is connected to the valve body.

The power element includes a housing to be assembled to the body, a diaphragm that divides the housing into a closed space and an open space, and a disk disposed in the open space. The sealed space is sealed with a gas for warming-up, and the open space communicates with the second passage. A part of the refrigerant flowing through the second passageway flows into the open space. The diaphragm is displaced by expansion or contraction of the closed space corresponding to the temperature and pressure of the refrigerant, and the driving force due to the displacement is transmitted to the shaft through the disk. When the refrigerant temperature at the outlet of the evaporator is lowered, the closed space is contracted, so that the valve portion operates in the valve closing direction. Conversely, when the refrigerant temperature rises, the closed space expands, so that the valve portion operates in the valve opening direction. The opening degree of the valve portion is adjusted by the autonomous operation of the power element, and the degree of superheat of the refrigerant at the outlet of the evaporator is properly controlled. In order to efficiently transfer the temperature of the refrigerant introduced into the open space to the diaphragm, a disk made of a material having a generally high thermal conductivity is used.

However, at the time of the bottom of the refrigeration cycle, the ratio of the liquid phase component in the refrigerant discharged from the outlet of the evaporator becomes large, and the liquid refrigerant (liquid droplet) is led to the open space of the power element and attached to the disk. The liquid refrigerant (liquid phase) has a smaller time constant of heat transfer (hereinafter, simply referred to as "time constant") than a gas refrigerant (vapor phase) . ≪ / RTI >

In order to suppress this hunting, a closing plate is provided in the communication passage for communicating the open space of the power element with the second passage, and the refrigerant is allowed to flow only through the pressure equalizing hole provided in the closing plate, (For example, refer to Patent Document 2). In this configuration, the closing plate is formed in a disk shape having a step, and a through hole is provided at the center of the shaft, and a pressure equalizing hole having a small diameter is provided at a position offset from the through hole. The closing plate is disposed such that the equalizing hole is opened to the downstream side of the shaft in the second passage. In addition, by fitting the small-diameter portion of the closing plate into the communication passage, the step at the position of the communication passage in the second passage is eliminated, and reduction of the refrigerant passage noise is realized.

[Prior Art Literature]

[Patent Literature]

Japanese Patent Application Laid-Open No. 2013-242129

Japanese Patent Application Laid-Open No. 2013-245921

However, in the structure described in Patent Document 2, it is necessary to process the equalizing hole in the closing plate separately from the insertion hole. In addition, it is necessary to secure the coaxiality between the outer shape of the closing plate and the insertion hole so as not to hinder the operation of the shaft, and the closing plate is required to have high processing accuracy. In addition, since the equalizing hole is offset from the center and the closing plate shows directionality, it is necessary to assemble the closing plate while confirming the position of the equalizing hole. This leads to an increase in the number of machining operations and the number of workings, and the manufacturing cost has been increased. On the other hand, as a result of the tests conducted by the inventors, it has not been recognized that the advantage of providing the pressure equalization holes on the downstream side of the shaft with respect to suppressing introduction of the liquid refrigerant into the power element was not recognized.

An object of the present invention is to solve such a problem, and an object thereof is to provide an expansion valve which functions well while preventing control hunting at a low cost.

The expansion valve according to an embodiment of the present invention controls the opening degree of the valve by sensing the pressure and the temperature of the refrigerant returned from the evaporator and expanding the refrigerant flowed from the upstream side to the evaporator. The expansion valve includes a first passage through which the refrigerant flowing from the upstream side to the evaporator passes, a second passage through which the refrigerant returned from the evaporator passes, a valve hole provided in the first passage, A mounting hole communicating with the body; A valve body contacting the valve hole to adjust an opening degree of the valve portion; A diaphragm that divides the inside of the housing into a closed space in which the thermosensitive medium is sealed and an open space communicating with the second passage; and a disk disposed in the open space and in contact with the diaphragm A power element; One end of the diaphragm is connected to the diaphragm through one of the first and second passages, and the other end of the diaphragm is connected to the valve, and the driving force in the axial direction due to the displacement of the diaphragm is transmitted to the valve body shaft; And an insertion hole for allowing the shaft to pass therethrough is provided along the central axis and the inflow of the refrigerant from the second passage to the open space is limited to the gap with the shaft in the insertion hole As shown in Fig.

The through hole has an opening area of 7.0 mm < 2 > or less formed by the gap with the shaft.

According to this embodiment, by providing the inflow restricting portion, inflow of the refrigerant from the second passage into the open space is allowed, but is appropriately restricted. Particularly, by setting the opening area of the insertion hole to the above setting, the occurrence of control hunting can be suppressed as described in the following embodiments. On the other hand, the insertion hole serves both as a function of inserting the shaft and a function of appropriately restricting the inflow of the refrigerant. Further, since a gap is formed between the insertion hole and the shaft, it is possible to reduce the necessity of strictly managing the dimensional accuracy of the inflow restricting portion. Therefore, it is possible to reduce the number of machining operations on the inflow restricting portion and to provide the inflation valve at low cost.

According to the present invention, it is possible to provide a functioning expansion valve at a low cost while preventing control hunting.

1 is a sectional view of an expansion valve according to an embodiment.
2 is a view showing a power element and its peripheral structure.
3 is a view showing the effect of the temperature sensing action of the expansion valve.
4 is a diagram showing the results of the Hunting verification test.
5 is a diagram showing the results of the Hunting verification test.
6 is a view showing the relationship between the opening degree of the insertion hole and the size of hunting.
7 is a view showing a structure of a main part of an expansion valve according to a modification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. On the other hand, in the following description, the positional relationship of each structure may be expressed on the basis of the illustrated state for convenience. In the following embodiments and modifications thereof, substantially the same constituent elements are denoted by the same reference numerals, and the description thereof may be appropriately omitted.

In the present embodiment, the expansion valve of the present invention is embodied as a thermostatic expansion valve applied to a refrigeration cycle of an air conditioner for an automobile. The refrigeration cycle includes a compressor for compressing the refrigerant circulating therein, a condenser (outdoor heat exchanger) for condensing the compressed refrigerant, a receiver for separating the condensed refrigerant into gas and liquid, an expansion valve for expanding and distributing the separated refrigerant, There is provided an evaporator (indoor heat exchanger) for evaporating the refrigerant in the mist state and cooling the air in the interior of the vehicle by the latent heat of evaporation. Here, for the sake of convenience, a detailed description is omitted except for the expansion valve.

1 is a sectional view of an expansion valve according to an embodiment.

The expansion valve (1) has a body (2) obtained by subjecting a member obtained by extrusion molding a material made of an aluminum alloy to a predetermined cutting process. The body 2 is formed in a prismatic shape, and a valve portion for expanding and contracting the refrigerant is provided inside. At the longitudinal end of the body 2, a power element 3 is provided.

An inlet port 6 for introducing refrigerant of a high temperature and a high pressure from the receiver (condenser side) is provided at the side of the body 2, an inlet port 6 for introducing refrigerant of low temperature and pressure, which has been narrowed and expanded by the expansion valve 1, An inlet port 8 for introducing the refrigerant evaporated by the evaporator, and an outlet port 9 for leading the refrigerant passing through the expansion valve 1 to the compressor side. In this embodiment, the introduction port 6 and the extraction port 9 are opened to the first side surface of the body 2. [ The lead-out port (7) and the lead-in port (8) are open to the second side opposite to the first side. In a modified example, the first side surface and the second side surface may be adjacent to each other at a plane perpendicular to each other. Between the introduction port 6 and the introduction port 9, a screw hole 10 for mounting a pipe (not shown) is formed. A joint of the pipe is connected to each port.

In the expansion valve 1, the first passage 13 is formed by the introduction port 6, the introduction port 7, and the refrigerant passage connecting them. A valve portion is provided at an intermediate portion of the first passage (13). The refrigerant introduced from the introduction port 6 is throttled and expanded by the valve portion to become a mist state, and is led out from the lead-out port 7 toward the evaporator. On the other hand, the second passage 14 is formed by the introduction port 8, the introduction port 9, and the refrigerant passage connecting them. The second passage 14 extends straight and has an intermediate portion communicating with the interior of the power element 3. A part of the refrigerant introduced from the introduction port 8 is supplied to the power element 3 and is warmed up. The refrigerant having passed through the second passage 14 is led out from the outlet port 9 toward the compressor.

A valve hole 16 is formed in an intermediate portion of the first passage 13 and a valve seat 17 is formed by an opening edge of the valve hole 16 on the side of the introduction port 6. The valve body 18 is disposed so as to face the valve seat 17 on the introduction port 6 side. The valve body 18 has a circular ball valve body 41 which is detachably attached to the valve seat 17 to open and close the valve portion and a valve body 43 for supporting the ball valve body 41 from below Consists of.

A communicating hole 19 for communicating the inside and the outside is formed in a lower portion of the body 2. A valve chamber 40 accommodating the valve body 18 is formed by the upper half thereof. The valve chamber (40) communicates with the valve hole (16) and is formed coaxially with the valve hole (16). The valve chamber 40 also communicates with the introduction port 6 through the upstream passage 37 at the side. The upstream passage 37 includes a small hole 42 that opens toward the valve chamber 40. The small hole (42) is formed by locally narrowing the passage cross section of the first passage (13).

The valve hole 16 communicates with the outlet port 7 through the downstream passage 39. That is, the upstream passage 37, the valve chamber 40, the valve hole 16, and the downstream passage 39 constitute the first passage 13. The upstream passage 37 and the downstream passage 39 are parallel to each other and extend in a direction perpendicular to the axis of the valve hole 16, respectively. On the other hand, in the modified example, even if the position of the introduction port 6 or the introduction port 7 is set so that the projections of the upstream passage 37 and the downstream passage 39 are orthogonal to each other good.

An adjusting screw (20) is fastened to the lower half of the communication hole (19) so as to seal the communication hole (19) from the outside. A spring 23 for biasing the valve body 18 in the valve closing direction is interposed between the valve body 18 (more precisely, the valve body 43) and the adjusting screw 20. The load of the spring 23 can be adjusted by adjusting the screw tightening amount of the adjusting screw 20 to the body 2. [ Between the adjusting screw 20 and the body 2, an O-ring 24 for preventing leakage of the refrigerant is interposed.

On the other hand, a support portion 60 protruding in a circular boss shape is provided at the center of the upper surface of the body 2, and a mounting hole 50 having a concave (circular hole shape with a bottom) is provided at the center of the support portion 60 . The communication hole 52 is provided so as to pass through the partition wall 51 between the mounting hole 50 and the second passage 14. The communication hole 52 is formed coaxially at the center of the bottom of the mounting hole 50. The power element 3 is assembled to the support portion 60 so that the lower portion thereof is screwed into the mounting hole 50 to seal the upper end opening of the body 2. [ Between the power element 3 and the body 2, an O-ring 30 for preventing the leakage of the refrigerant is interposed.

The power element 3 has a housing 25 mounted on the body 2 to close the mounting hole 50 and a diaphragm 28 which axially divides the inside of the housing 25. The housing 25 is constructed by assembling the upper housing 26 and the lower housing 27 in the axial direction. The upper housing 26 functions as a "first housing " and the lower housing 27 functions as a" second housing ".

That is, the power element 3 is constituted by disposing the diaphragm 28 between the upper housing 26 and the lower housing 27, and disposing the disk 29 on the lower housing 27 side . The upper housing 26 is obtained by press-molding a stainless steel material in the form of a lid. The lower housing 27 is obtained by press-molding a stainless steel material into a cylindrical shape having a step. The disk 29 is made of, for example, aluminum or an aluminum alloy, and has a higher thermal conductivity than the two housings.

The power element 3 is assembled such that the openings of the upper housing 26 and the lower housing 27 face each other and the outer edge portion of the diaphragm 28 is fitted to the outer edge portion of the upper housing 26 and the lower housing 27, And is formed in the form of a container by performing outer circumferential welding. The inside of the power element 3 is partitioned into a closed space S1 and an open space S2 by a diaphragm 28 and a warming gas (which functions as a "temperature sensing medium") It is sealed. The disc 29 is disposed in the open space S2.

A disk-shaped plate 31 is disposed at the bottom of the mounting hole 50. The plate 31 is provided with an insertion hole 36 for passing the shaft 33 through the center while separating the second passage 14 from the open space of the power element 3. The plate 31 functions as an inflow restriction portion for limiting the inflow of the refrigerant from the second passage 14 to the open space S2 to the gap between the second passage 14 and the shaft 33 in the insertion hole 36 do. A part of the refrigerant passing through the second passage 14 is led to the open space S2 through the communication hole 52 and the insertion hole 36. [ The power element 3 senses the pressure and temperature of the refrigerant and generates a driving force in the opening and closing direction of the valve portion. The warming-up structure of the power element 3 will be described later in detail.

A through hole 34 is provided in the center of the body 2 so as to pass through the partition wall 35 which separates the first passage 13 and the second passage 14 from each other. The insertion hole 34 is a hole having a stepped portion including the small diameter portion 44 and the large diameter portion 46 coaxially. The lower end of the small diameter portion 44 is opened toward the first passage 13 and the upper end of the large diameter portion 46 is opened toward the second passage 14. [ The small diameter portion 44 slidably inserts the long shaft 33 in the axial direction. The large-diameter portion (46) forms a mounting hole for accommodating the later-described anti-vibration spring (48) in a coaxial shape.

The shaft 33 is a metal rod made of stainless steel or the like and is interposed between the disk 29 and the valve body 18. [ Thereby, the driving force by the displacement of the diaphragm 28 is transmitted to the valve body 18 through the disk 29 and the shaft 33, and the valve portion is opened and closed. One end side of the shaft 33 traverses the second passage 14 and is connected to the disk 29 through the plate 31. The other end side of the shaft 33 traverses the downstream passage 39 of the first passage 13 and is connected to the valve element 18 through the valve hole 16. [

The large diameter portion 46 accommodates a vibration spring 48 for imparting a biasing force to the shaft 33 in a direction perpendicular to the axial direction, that is, a lateral load (sliding load). The vibration of the shaft 33 and the valve element 18 due to the fluctuation of the coolant pressure is suppressed by the shaft 33 receiving the lateral load of the vibration springs 48. [

The vibration-proof spring 48 is fixed coaxially with the small-diameter portion 44, and supports the shaft 33 in a coaxial manner. The anti-vibration spring 48 biases the shaft 33 radially inward to impart sliding resistance. On the other hand, as for the concrete structure of the dust-proof spring 48, for example, the structure described in Japanese Patent Application Laid-Open No. 2013-242129 can be adopted, and a detailed description thereof will be omitted.

The clearance between the insertion hole 34 and the shaft 33 is reduced to realize the clearance sealing in which the leakage of the refrigerant from the first passage 13 to the second passage 14 is suppressed. A sealing ring such as an O ring may be disposed between the insertion hole 34 and the shaft 33 to prevent the refrigerant from leaking from the first passage 13 to the second passage 14. [

In the expansion valve 1 configured as described above, the diaphragm 28 is displaced by the power element 3 sensing the pressure and temperature of the refrigerant returned from the evaporator through the introduction port 8. The displacement of the diaphragm 28 becomes a driving force and is transmitted to the valve body 18 through the disk 29 and the shaft 33 to open and close the valve portion. On the other hand, the liquid refrigerant supplied from the receiver is introduced from the introduction port 6 and expanded and throttled as it passes through the valve portion, and becomes a low-temperature low-pressure, misty refrigerant. The refrigerant is led out from the outlet port 7 toward the evaporator.

Next, the warming-up structure of the power element will be described in detail.

2 is a view showing a power element and its peripheral structure. Fig. 2 (A) is an enlarged view of part A in Fig. 1, and Fig. 2 (B) is a plan view of the plate 31. Fig.

2 (A), a female screw portion 62 is formed on the inner peripheral surface of the mounting hole 50. As shown in Fig. The above-described communication hole 52 is provided at the bottom center of the mounting hole 50 (partition wall 51). A locking surface 64 is formed on the upper surface of the body 2 and an O-ring 30 is fitted in the fitting groove 65 formed in the locking surface 64. [

On the other hand, the lower housing 27 is in the form of a cylinder having steps whose diameter gradually decreases downward, and the lower half of the lower housing 27 constitutes a connecting portion 66. On the outer circumferential surface of the connection portion 66, a male screw portion 68 (functioning as a "screw portion") capable of screwing with the female screw portion 62 is formed. The lower housing 27 is attached to the body 2 by screwing the connection portion 66 to the mounting hole 50. [ The base portion of the connection portion 66 in the lower housing 27 serves as a locking surface 70 perpendicular to the axis and is fixed to the locking surface 64 of the body 2. [ As shown in Fig.

The disk 29 includes a disk-shaped main body 72 and a heat transfer promoting portion 74 extending downward from the bottom center of the main body 72. As shown in the drawing, the temperature of the refrigerant introduced into the open space S2 can be efficiently transmitted by taking the side surface of the heat transfer promoting section 74 large. The outer diameter of the heat transfer promoting portion 74 is slightly smaller than the inner diameter of the connecting portion 66. A recess 76 is formed at the center of the lower surface of the heat transfer promoting portion 74 so as to be downwardly tapered in diameter. A groove portion 53 is provided on the lower surface of the main body 72. The refrigerant flowing into the open space S2 is led to the lower surface of the diaphragm 28 through the groove portion 53. [

As shown in Fig. 2 (B), the plate 31 is in the shape of a disk having a flat upper and lower surfaces, and a through hole 36 is provided coaxially along the central axis. The plate 31 is coaxially supported at the bottom of the mounting hole 50, and the shaft 33 is coaxially inserted. On the other hand, the term "coaxial " as used herein includes not only the case where the axes completely coincide with each other, but also the case where they coincide with each other. The outer diameter of the plate 31 is almost the same as the inner diameter of the mounting hole 50, but slightly smaller. Thereby, the plate 31 is easily assembled. The thickness of the plate 31 is slightly smaller than the distance L between the bottom of the mounting hole 50 and the lower end of the lower housing 27. The lower end of the lower housing 27 is opposed to the upper surface in the vicinity of the outer peripheral edge of the plate 31. The distance between them is smaller than the thickness of the plate 31. [

By providing a clearance between the plate 31 and the lower housing 27 in this way, the lower housing 27 can be securely fastened to the body 2 and the sealing function of the O-ring 30 can be ensured . On the other hand, by making the distance between the lower end of the lower housing 27 and the plate 31 small, it is possible to suppress this even if the diarrhea plate 31 is jolted.

The upper portion of the shaft 33 extends through the insertion hole 36 to the open space S2 and its distal end is inserted into the concave portion 76 to abut the lower surface of the disk 29. [

The plate 31 is made of resin, has a hardness lower than that of the housing 25, and has a low thermal conductivity. The cross sectional area of the gap between the insertion hole 36 and the shaft 33 (referred to as "opening area of the insertion hole 36 "; see the dotted area) Limit refrigerant inflow / outflow. The opening area is set to a size (a size capable of suppressing the inflow of liquid droplets) so as to accelerate passage of the gas refrigerant (gas phase component) and inhibit passage of the liquid refrigerant (liquid phase component). And is about 5 mm 2 in the present embodiment.

When assembling the power element 3 to the body 2, the plate 31 is previously inserted into the mounting hole 50 and the O-ring 30 is fitted into the fitting groove 65, 27 are screwed into the mounting hole 50. [ As a result, the O-ring 30 is pressed against both the power element 3 and the body 2 to ensure sealing performance. When the lower housing 27 is screwed in this manner, the engaging surface 70 is engaged with the engaging surface 64 of the body 2, and the assembling of the power element 3 is completed.

Next, the operation and effect of the present embodiment will be described in detail.

3 is a view showing the effect of the temperature sensing action of the expansion valve. Fig. 3 (A) shows the temperature sensing action of the expansion valve 1 according to the present embodiment, and Fig. 3 (B) shows the temperature sensing action of the expansion valve 101 according to the comparative example. In contrast to the case where the expansion valve 1 is provided with the plate 31, the two are different from each other in that the expansion valve 101 does not have this. The double-dotted line arrows in the drawing indicate the flow of the refrigerant. In the drawings, the same components are denoted by the same reference numerals.

3 (A), a leading end (joint) of a pipe 80 connecting the outlet side of the evaporator and the expansion valve 1 is connected to the introduction port 8. An O-ring 82 for sealing is fitted to the outer peripheral surface of the distal end of the pipe 80 to prevent the refrigerant from leaking to the outside. A flange portion 84 protruding outward in the radial direction is formed in the vicinity of the tip of the pipe 80. The flange portion 84 is engaged with the side surface of the body 2, 14 of the pipe 80 is defined.

On the other hand, a leading end (joint) of a pipe 90 connecting the inlet side of the compressor to the expansion valve 1 is connected to the outlet port 9. An O-ring 92 for sealing is fitted to the outer circumferential surface of the distal end portion of the pipe 90 to prevent the refrigerant from leaking to the outside. A flange 94 protruding outward in the radial direction is formed in the vicinity of the tip of the pipe 90. The flange 94 is engaged with the side surface of the body 2, 14 of the pipe 90 is defined. On the other hand, the pipes 80 and 90 are fixed to the body 2 through respective pipe fixing plates (not shown), but the description thereof will be omitted.

In this embodiment, most of the refrigerant extracted from the evaporator goes straight from the outlet of the pipe 80 to the second passage 14, enters the inlet of the pipe 90, and is delivered to the compressor. A part of the refrigerant flows so as to diffuse from the outlet of the pipe 80 and contacts the inner side surface of the front end 96 of the pipe 90 and the downstream side of the communication hole 52 to change the direction, As shown in FIG. However, most of the refrigerant that has been turned in the direction of contact with the plate 31 is returned to the second passage 14 and is led to the inlet of the pipe 90. A part of the refrigerant turned in the direction passes through the insertion hole 36 and is led to the open space S2.

On the other hand, the refrigerant in the open space S2 is conversely drawn to the second passage 14 through the through hole 36 and the communication hole 52, and is led to the inlet of the pipe 90. In this way, the refrigerant is appropriately introduced into the open space S2. Thereby, the power element 3 can reliably detect the temperature and pressure of the outlet of the evaporator in real time. When the liquid refrigerant is delivered to the communication hole 52, the liquid refrigerant is positively blocked by the plate 31 and is prevented from being introduced into the open space S2. For this reason, control hunting is prevented or suppressed.

On the other hand, in the comparative example shown in Fig. 3 (B), when the liquid refrigerant is delivered to the communication hole 52, the liquid refrigerant is directly introduced into the open space S2. For this reason, there is a high possibility of generating control hunting. In other words, according to the present embodiment, the control hunting can be effectively suppressed merely by disposing the plate 31 having the simple structure in the mounting hole 50. [

4 and 5 are diagrams showing the results of the Hunting verification test. In this test, the flow of the refrigerant when the refrigeration cycle was operated was visualized by using the specimen in which the body and the housing were made of transparent resin. FIG. 4 shows the experimental results of this embodiment, and FIG. 5 shows the experimental results of the comparative example. The comparative example does not include the plate 31 of the present embodiment. The upper part of each drawing shows the flow of the refrigerant near the warming part when the superheat degree is zero and the lower part shows the measurement result of hunting when the refrigerating cycle is switched from the minimum capacity operation to the normal operation. In the lower part of each figure, the horizontal axis represents the elapsed time (second) from the operation switching of the refrigeration cycle, and the vertical axis represents the degree of superheat (° C) of the refrigerant at the outlet of the evaporator. 6 is a view showing the relationship between the opening degree of the insertion hole 36 and the size of hunting. The horizontal axis in FIG. 6 represents the opening area (mm 2) of the through hole 36, and the vertical axis represents the amplitude (° C.) of the superheat degree.

As shown in the lower part of FIG. 4, according to the present embodiment, it is found that the superheat degree becomes substantially constant and stable when approximately 200 seconds have elapsed from the operation switching. Further, as shown in the upper part of Fig. 4, it can be seen that when the superheat degree is zero, that is, when the refrigerant is in the gas-liquid two phase state, the gas phase component is stably introduced into the open space S2. On the other hand, as shown in the lower part of FIG. 5, in the comparative example, it can be seen that the degree of superheat greatly fluctuates regardless of the passage of time. As shown in the upper part of Fig. 5, it can be seen that the gas-liquid two-phase refrigerant flows strongly into the open space S2 in a state where the superheat degree is zero (see bubble state). On the other hand, about 200 seconds after the operation switching is a time until the refrigerating cycle shifts to the normal operation and is stabilized. Therefore, when compared in the normal operation state of the refrigeration cycle, control hunting is conspicuous in the comparative example, but it is understood that the control hunting is suppressed in this embodiment.

As shown in FIG. 6, it was found that the effect of hunting suppression according to the present embodiment is increased by allowing the refrigerant to flow through the insertion hole 36 while setting the opening area to 7.0 mm 2 or less.

As described above, according to the present embodiment, the plate 31 separating the open space S2 of the power element 3 from the second passage 14 is provided, and in the plate 31, By setting the opening area of the hole 36 to 7.0 mm 2 or less, occurrence of control hunting is effectively suppressed. In addition, since the plate 31 has a simple shape in which the insertion hole 36 is provided at the center of the flat disk, the sheet 31 can be easily obtained simply by punching the sheet material into the shape thereof. . Since the shape of the plate 31 is symmetrical with respect to the center thereof and has no directionality, assembly into the body 2 is also easy. Even if there is an error in the dimensional accuracy of the diaphragm plate 31, the shaft 33 does not interfere with the shaft 33 because the gap between the insertion hole 36 and the shaft 33 is appropriately spaced to promote the passage of the gas refrigerant. Do not. That is, it is possible to reduce the necessity of strictly controlling the dimensional accuracy of the plate 31. [ In other words, it is possible to reduce the number of working steps for manufacturing and assembling the plate 31, and the expansion valve 1 can be realized at low cost.

[Modifications]

7 is a view showing a structure of a main part of an expansion valve according to a modification. 7 (A) shows a first modification, and Fig. 7 (B) shows a second modification.

As shown in Fig. 7 (A), in the first modified example, the "inflow restriction portion" is provided integrally with the power element 203. [ That is, the plate 231 is fixed to the opening end of the lower housing 27. The fixing method may be press fitting, or other fixing means such as welding, caulking, and fastening (screwing) may be employed. The plate 231 has a through hole 36 at the center thereof and restricts the inflow of the refrigerant from the second passage 14 into the open space S2. With this arrangement, control hunting can be suppressed in the same manner as in the above embodiment. On the other hand, the plate 231 may be made of resin or metal. In the latter case, it may be made of aluminum or aluminum alloy, or may have a higher thermal conductivity than the housing 25.

As shown in Fig. 7 (B), in the second modified example, the "inflow restriction portion" is a disk-shaped plate 331 having a step. The plate 331 includes a main body 310 supported at the bottom of the mounting hole 50 and a fitting portion 312 partially inserted into the communication hole 52. An insertion hole 36 is provided so as to pass through the center of the plate 331 in the axial direction. With this arrangement, control hunting can be suppressed in the same manner as in the above embodiment. Further, even if the plate 331 is not press-fitted into the body 2, the state of assembly to the body 2 can be stabilized.

Although the preferred embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the specific embodiments, and various modifications are possible within the scope of the technical idea of the present invention.

In the above embodiment, the outer diameter of the plate 31 is made slightly smaller than the inner diameter of the mounting hole 50, and the ease of assembly of the plate 31 is improved. Even if the diaphragm plate 31 and the shaft 33 are offset from each other by such a configuration, the size (opening area) of the insertion hole 36 is set so as not to interfere with the shaft 33 Is set. That is, the size (opening area) of the insertion hole 36 is set so that the clearance between the insertion hole 36 and the shaft 33 becomes larger than the clearance between the plate 31 and the mounting hole 50. In the modified example, the plate 31 may be provided with a press-fit margin and press-fitted into the mounting hole 50.

The thickness of the plate 31 is set to be slightly smaller than the distance L between the bottom of the mounting hole 50 and the lower end of the lower housing 27 and the distance between the plate 31 and the lower housing 27 In order to make room for. In this modification, the plate 31 may be sandwiched between the body 2 and the lower housing 27 without providing such a margin. Thereby, the plate 31 can be stably supported. In this case, it is preferable that the plate 31 is made of a resin material, or the hardness is smaller than that of the lower housing 27.

In the above embodiment, the power element 3 (the housing 25) is assembled to the body 2 by screwing the threaded portion. In a modified example, the power element (housing) and the body may be assembled by press-fitting or caulking.

The expansion valve of the above embodiment is preferably applied to a refrigeration cycle using an alternative refrigerant (HFC-134a) or the like as a refrigerant, but the expansion valve of the present invention is applied to a refrigeration cycle using a refrigerant having a high operating pressure such as carbon dioxide You may. In this case, an external heat exchanger such as a gas cooler is disposed instead of the condenser in the refrigeration cycle.

In the above embodiment, the expansion valve is exemplified as constituted by throttling the refrigerant flowing through the external heat exchanger and supplying it to an evaporator (indoor evaporator). In a modified example, the expansion valve may be applied to a heat pump type vehicle cooling / heating apparatus and installed downstream of the indoor condenser (indoor heat exchanger). That is, the expansion valve may be constituted such that the refrigerant flowing in via the indoor condenser is expanded and supplied to the external heat exchanger (outdoor evaporator).

On the other hand, the present invention is not limited to the above-described embodiments and modifications, and can be embodied by modifying the constituent elements without departing from the gist of the invention. Various inventions may be formed by appropriately combining a plurality of constituent elements disclosed in the above embodiments or modifications. In addition, some components may be deleted from all the components shown in the above embodiments or modifications.

1: Expansion valve
2: Body
3: Power element
6: Introduction port
7: Lead port
8: Introduction port
9: Lead port
13: first passage
14: second passage
16: Valve hole
18: Valve body
25: Housing
28: Diaphragm
29: Disc
31: Plate
33: Shaft
34: Insertion hole
36: Insertion hole
50: Mounting hole
51:
52: communicating hole
80: Piping
90: Piping
203: Power element
231: Plate
S1: Enclosed space
S2: Open space

Claims (8)

An expansion valve for expanding the refrigerant flowing from the upstream side to supply the expanded refrigerant to the evaporator and sensing the pressure and temperature of the refrigerant returned from the evaporator to control the opening degree of the valve portion,
A first passage through which the refrigerant flowing from the upstream side to the evaporator passes, a second passage through which the refrigerant returned from the evaporator passes, a valve hole provided in the first passage, and a second passage communicating with the second passage A body having a mounting hole;
A valve body contacting the valve hole to adjust an opening degree of the valve portion;
A diaphragm that is disposed in the open space and separates the inside of the housing into a closed space in which the thermosensitive medium is sealed and an open space communicating with the second passage; A power element having a disk in contact with the disk;
The diaphragm having one end connected to the diaphragm and the other end connected to the valve body through the partition between the first passage and the second passage so that the driving force in the axial direction due to the displacement of the diaphragm To the valve body; And
And an opening for passing the shaft therethrough is formed coaxially along the central axis while the refrigerant flows from the second passage to the open space through the insertion hole And an inflow restricting portion for restricting a gap between the shaft and the shaft,
Wherein the insertion hole is formed such that an opening area formed by an interval from the shaft is 7.0 mm < 2 > or less. The method according to claim 1,
Wherein the inflow restriction portion is composed of a shielding member which is disposed between the body and the housing and whose fall-off from the mounting hole is restricted. 3. The method of claim 2,
Wherein the shielding member is formed of a flat circular plate and the insertion hole is formed at the center thereof. The method according to claim 2 or 3,
Wherein the body has a communication hole communicating the mounting hole and the second passage,
Wherein the shielding member is supported by a step formed at a boundary between the mounting hole and the communication hole. 5. The method of claim 4,
Wherein the outer diameter of the shielding member is smaller than the inner diameter of the mounting hole, and the shielding member is not fixed in the radial direction with respect to the mounting hole. The method according to claim 2 or 3,
Wherein the shielding member is sandwiched between the housing and the body. The method according to claim 6,
Wherein the inflow restriction portion is made of a resin material having a hardness lower than that of the housing. 4. The method according to any one of claims 1 to 3,
And the insertion hole has a shape of a garden shape.

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