Valve device

A valve device is provided. In the valve device, a valve element is rotated about a support shaft, based on rotation of a valve element drive member to switch a through hole that communicates with an outlet formed in a valve seat to adjust a flow rate. The through hole opens in a bottom surface of a flow channel securing groove formed in the valve element. The flow channel securing groove has a long hole shape in which a width in a first direction being a moving direction of the valve element, is smaller than a width in a second direction orthogonal to the first direction. Thus, a region overlapping with the outlet is large as compared to a case where a perfect circular flow channel securing groove is formed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a 371 application of the international PCT application serial no. PCT/JP2018/016519, filed on Apr. 24, 2018, which claims the priority benefits of Japan application no. 2017-092849 filed on May 9, 2017. The entirety of each of the abovementioned patent applications is hereby incorporated by reference herein and made a part of this specification.

TECHNICAL FIELD

The present invention relates to a valve device for adjusting a flow rate of fluid.

BACKGROUND ART

Patent Literature 1 describes a refrigerant valve device for adjusting a supply amount of refrigerant for cooling an interior of a refrigerator. In the refrigerant valve device of Patent Literature 1, a valve chamber is formed between a base including a valve seat surface on which a refrigerant inlet and a refrigerant outlet open and a cover that covers the base. A valve element is arranged in the valve chamber to overlap with the refrigerant outlet. The valve element rotates about an axis orthogonal to the valve seat surface, based on rotation of an output gear rotated by a stepping motor. A through hole (orifice) is formed in the valve element. The orifice includes a narrow tube part through which fluid passes. When the valve element is positioned at a rotational position where the refrigerant outlet formed on the valve seat surface and the orifice overlap, the fluid flows through the orifice. In addition, the valve element may be positioned at a rotational position where the refrigerant outlet and the orifice do not overlap so that the fluid flows through a pathway by way of a flow channel groove formed in the valve element.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

The refrigerant valve device of Patent Literature 1 controls the rotational position of the valve element by the number of driving steps of the stepping motor. Thus, in rotational positions of the valve element, variations due to component tolerances are generated. For example, a variation in rotational positions of the valve element is generated due to a variation, and the like in magnetization of a magnet of the stepping motor. Therefore, to allow the fluid to flow at a flow rate corresponding to a hole diameter of the orifice even if there is a variation in rotational positions of the valve element, the valve element is formed with a circular concave part around the orifice. An inner diameter of the concave part is larger than that of the orifice. Therefore, even if there is a displacement between the position of the orifice and the refrigerant outlet, due to a variation in rotational positions of the valve element, if the overlap between the concave part and the refrigerant outlet is greater than or equal to a cross-sectional area of the orifice, it is possible to circulate the fluid at a flow rate corresponding to a narrow tube diameter of the orifice.

However, as in Patent Literature 1, if a perfect circular concave part around the through hole (orifice) is formed in the valve element, a circular space around the through hole is required to be secured in the valve element. Therefore, there is a problem that a degree of freedom in position where the through hole is formed is low.

In view of the above problems, an object of the present invention is to provide a valve device capable of flowing fluid at a flow rate corresponding to a hole diameter of a through hole formed in a valve element even if there is a variation in positions of the valve element, and having a high degree of freedom in position of the through hole.

Means for Solving the Problem

To solve the above problems, a valve device of the present invention includes: a valve chamber to be supplied with fluid; a valve seat surface provided inside the valve chamber; a valve element mounted at a position overlapping with an opening part provided in the valve seat surface; a valve element drive member that moves the valve element along the valve seat surface; and a drive source that drives the valve element drive member, wherein the valve element includes a concave part provided on an abutment surface abutting against the valve seat surface, and a through hole opening in a bottom surface of the concave part, and in the concave part, a width in a first direction being a movement direction of the valve element by the valve element drive member is smaller than a width in a second direction orthogonal to the first direction.

According to the present invention, when the valve element is moved, the through hole formed in the valve element and the opening part formed in the valve seat surface can be communicated. The valve element is formed with a concave part larger than the hole diameter of the through hole, and the through hole opens in the bottom surface of the concave part. Therefore, even if there is a variation in positions of the valve element, as long as a size of the concave part corresponds to the variation, the fluid can be flowed at a flow rate corresponding to the hole diameter of the through hole. Moreover, the concave part has a shape in which the width in the first direction being the movement direction of the valve element is smaller than the width in the second direction orthogonal to the first direction. Thus, if the concave part is not a perfect circle in shape, but is long in shape in a direction orthogonal to the movement direction of the valve element, an area of a part overlapping with the opening part on the valve seat side can be secured while the concave part is small in width in the first direction. Therefore, the width in the first direction can be decreased as compared to a case where the perfect circular concave part is provided. Therefore, in the valve element, there is a sufficient space in the first direction, and thus, the degree of freedom in position of the concave part can be increased, and the degree of freedom in position of the through hole formed in the concave part can be also increased.

In the present invention, it is desirable that an edge of the concave part includes a straight line part located on either side of the through hole in the first direction. In this way, when the opening part on the valve seat side and the concave part partially overlap with each other, an overlapping part is formed in a shape cut off by a straight line. On the other hand, an overlapping part obtained when the concave part is circular is in a shape cut by an arc, and thus, the concave part having a shape including the straight line part can secure a larger overlapping area. That is, a large overlapping area can be secured even if the width of the concave part in the first direction is decreased. Therefore, the degree of freedom in position of the concave part and the through hole can be increased.

In the present invention, the valve element drive member rotates the valve element about a rotation axial line perpendicular to the valve seat surface, and the opening part is located on a movement trajectory of the through hole obtained when the valve element rotates about the rotation axial line. Therefore, a state in which the opening part is in communication with the through hole and a state in which the opening part is not in communication with the through hole can be switched by the rotation of the valve element. In such a configuration, it is desirable that the first direction is a circumferential direction around the rotation axial line, the second direction is a radial direction around the rotation axial line, and the concave part has a long hole shape in which a width in the circumferential direction is smaller than a width in the radial direction. As a result, even if there is a variation in rotational positions of the valve element, the fluid can be flowed at a flow rate corresponding to the hole diameter of the through hole. Moreover, even if the width in the circumferential direction of the concave part is small, the area of the part overlapping with the opening part on the valve seat side can be secured. Therefore, the degree of freedom in position of the concave part can be increased and the degree of freedom in position of the through hole formed in the concave part can be increased.

In the present invention, it is desirable that an outer shape of the valve element is circular around the rotation axial line and the through hole is circular. If the valve element is circular and the through hole is circular, the through hole may be provided at any position in the circumferential direction of the valve element. Therefore, the degree of freedom in position of the through hole is high.

In the present invention, it is desirable that a center in the radial direction of the concave part is closer to a rotation center of the valve element than an outer peripheral edge of the valve element. Thus, when the concave part is formed at a position near the rotation center of the valve element, a space on a side of the center of the valve element can be effectively utilized. Moreover, in the present invention, the width in the circumferential direction of the concave part can be decreased, and thus, the concave part can be arranged in a space on the side of the center of the valve element.

In the present invention, the through hole includes a plurality of through holes and the valve element is formed with the plurality of through holes, at least some of the plurality of through holes are different in hole diameter, and the concave part includes a plurality of concave parts and the abutment surface is formed with the plurality of concave parts corresponding to the plurality of through holes at positions spaced apart from one another. Further, if the valve element rotates about the rotation axial line perpendicular to the valve seat surface, the through hole includes a plurality of through holes and the plurality of through holes are arrayed in the circumferential direction around the rotation axial line, at least some of the plurality of through holes are different in hole diameter from one another, and the concave part includes a plurality of concave parts and the abutment surface is formed with the plurality of concave parts corresponding to the plurality of through holes at positions spaced apart from one another in the circumferential direction. In this way, when the valve element is moved (rotated), the hole diameters of the through holes in communication with the opening parts on the valve seat side can be switched. Therefore, the flow rate of the fluid can be adjusted. In addition, the valve element is provided with the concave part corresponding to the hole diameter of the through hole, even if the rotational position of the valve element is displaced, the fluid having a flow rate corresponding to the hole diameter of the through hole can be passed. Therefore, the accuracy of flow rate adjustment can be increased.

In the present invention, it is desirable that the valve element includes a flow channel groove formed on an opposite surface facing an opposite side of the abutment surface, and the through hole opens in a bottom surface of the flow channel groove. In this way, the through hole and the valve chamber can be communicated by way of a valve chamber side flow channel groove so that a length of the through hole can be shortened in the thickness direction of the valve element.

In the present invention, it is desirable that the opposite surface faces the valve element drive member, and the opposite surface is provided with a support surface abutting against with the valve element drive member. In this way, an inclination of the valve element can be regulated by the support surface, and thus, a sealing performance of the valve element can be improved.

In the present invention, the valve element is formed with a fitting concave part that fits with the valve element drive member, and the fitting concave part is connected to the flow channel groove. Thus, if the fitting concave part and the flow channel groove are formed continuously, it is possible to provide a good space efficiency when the fitting concave part and the flow channel groove are formed. Therefore, the degree of freedom in position where the fitting concave part and the flow channel groove are formed can be increased, and the degree of freedom in position of a penetration part opening in the bottom surface of the flow channel groove can be increased.

In the present invention, it is desirable that a depth of the concave part is greater than that of the hole diameter of the through hole. In this way, the depth of a flow channel in the concave part can be secured, and thus, it is possible to avoid a case where the flow rate is regulated when the fluid passes the concave part. Therefore, the fluid can be circulated at a flow rate corresponding to the hole diameter of the through hole.

In the present invention, it is desirable that the abutment surface is formed with a cutaway part at a position separated from the concave part, the cutaway part has a width in the first direction larger than a width in the first direction of the opening part and opens to an outer peripheral surface of the valve element. In this way, the fluid can be circulated at a flow rate determined based on an opening diameter of the opening part on the valve seat side.

In the present invention, it is desirable that the drive source is a stepping motor; the valve element drive member is a gear member having a tooth part formed on an outer peripheral surface of the valve element drive member, and a driving force of the drive source is transmitted to the valve element drive member where rotation from the drive source is decelerated. In this way, even if there is a variation in positions of the valve element, which cannot be eliminated by the regulation of the stepping motor, the fluid can be flowed at a flow rate corresponding to the hole diameter of the through hole.

Effect of the Invention

According to the present invention, when the valve element is moved, the through hole formed in the valve element and the opening part formed in the valve seat surface can be communicated. The valve element is formed with the concave part larger than the hole diameter of the through hole, and the through hole opens in the bottom surface of the concave part, and thus, even if there is a variation in positions of the valve element, the fluid can be flowed at a flow rate corresponding to the hole diameter of the through hole. Moreover, the concave part has a shape in which the width in the first direction being the movement direction of the valve element is smaller than the width in the second direction orthogonal to the first direction. As a result, even if the width in the first direction is small, the area of the part overlapping with the opening part on the valve seat side can be secured. Therefore, the width in the first direction can be decreased as compared to a case where the perfect circular concave part is provided. Therefore, in the valve element, there is a sufficient space in the first direction, and thus, the degree of freedom in position of the concave part can be increased, and the degree of freedom in position of the through hole formed in the concave part can be also increased.

MODE FOR CARRYING OUT THE INVENTION

An embodiment of a valve device to which the present invention is applied will be described with reference to the drawings below. The valve device according to the present embodiment is a refrigerant valve device provided between a compressor and a cooler in a refrigerant flow channel in a refrigerator and used for adjusting a flow rate of a refrigerant. It is noted that the valve device of the present invention is not limited in use to adjustment of a refrigerant flow rate, and can be applied to valve devices for other uses.

FIG. 1AandFIG. 1Bare perspective views of a valve device to which the present invention is applied.FIG. 1Ais a perspective view seen from a side of a valve main body, andFIG. 1Bis a perspective view seen from a side of an inflow pipe and an outflow pipe.FIG. 2is a bottom surface view of the valve device ofFIG. 1AandFIG. 1B. A valve device1includes a valve main body2, and an inflow pipe3and an outflow pipe4extending in parallel from the valve main body2. The valve main body2includes a connector5that provides electric connection with an external control device, and a mounting plate6that mounts the valve device1in a refrigerator. It is noted that in the following description, for convenience, a direction in which the inflow pipe3and the outflow pipe4are extendedly provided will be referred to as an up-down direction, the valve main body2will be described as an upper side, and the inflow pipe3and the outflow pipe4will be described as a lower side.

FIG. 3is a cross-sectional view of the valve device1(cross-sectional view taken along line A-A inFIG. 2). The valve main body2includes an exterior case9covering the upper side of the mounting plate6. Inside the exterior case9, a cup-shaped sealing cover11is arranged in a disk-shaped base10covered from above. The sealing cover11is fitted from below into a circular opening part7formed in the mounting plate6. The base10is exposed on a bottom surface of the valve device1.

In a center of the base10, a shaft hole13that rotatably supports a rotor support shaft62of a stepping motor60described later is formed. Further, a refrigerant inlet12that makes connection of the inflow pipe3is formed at a position near an outer periphery of the base10, and a valve seat attachment hole14or circular opening part is provided on the opposite side of the refrigerant inlet12across the shaft hole13. A circular valve seat40is fitted in the valve seat attachment hole14. The valve seat40is exposed on the bottom surface of the valve device1, and the outflow pipe4is connected to a refrigerant outlet43formed in the valve seat40. Further, a base-side flange16(seeFIG. 3) that has a plate thickness thinner than that of a center part of the base10is formed on an outer peripheral edge of the base10.

The sealing cover11is formed by pressing a nonmagnetic stainless steel plate. As illustrated inFIG. 3, the sealing cover11includes, from an upper direction to a lower direction, a circular bottom part111, a small-diameter cylindrical part112that extends downward from an outer peripheral edge of the bottom part111, a large-diameter cylindrical part113that has a larger diameter than the small-diameter cylindrical part112, and a cover-side flange114that expands radially outward from a lower end edge (opening edge) of the large-diameter cylindrical part113. The small-diameter cylindrical part112and the large-diameter cylindrical part113are connected via an annular part115set perpendicular to an axis L0that passes through the center of the base10. The sealing cover11is fixed to the base10with the cover-side flange114that abuts against the base-side flange16. Between the sealing cover11and the base10, a valve chamber30being a flow channel in which the refrigerant is stored is formed.

The valve device1includes a flow rate adjustment mechanism8that adjusts the flow rate of fluid (refrigerant) that flows from the valve chamber30to the outflow pipe4. The flow rate adjustment mechanism8includes the stepping motor60being a drive source. The stepping motor60includes a rotor61arranged inside the sealing cover11and a stator64configured between the sealing cover11and the exterior case9. The rotor61includes a permanent magnet63arranged on an outer peripheral surface thereof, and is rotatably supported by the rotor support shaft62. The rotor support shaft62has an upper end thereof fixed to the bottom part111of the sealing cover11and a lower end thereof fixed to the center of the base10. An axis of the rotor support shaft62coincides with the axis L0that passes through the center of the base10and extends in parallel with an axis L of a support shaft29that rotatably supports a valve element drive member50and a valve element20described later. A pinion66that rotates together with the rotor61is formed at a lower end of the rotor61. The pinion66is arranged in the valve chamber30.

The stator64is supported by the annular part115of the sealing cover11from below and is arranged on an outer peripheral side of the small-diameter cylindrical part112of the sealing cover11. The stator64includes a coil65, and the coil65faces the permanent magnet63of the rotor61through the small-diameter cylindrical part112of the sealing cover11. The coil65is electrically connected to the connector5. An operation of the stepping motor60is controlled by an external control device connected via the connector5.

FIG. 4is a perspective view illustrating a main part of the flow rate adjustment mechanism8.FIG. 5AandFIG. 5Bare exploded perspective views of the valve element drive member50, the valve element20, and the valve seat40, whereFIG. 5Ais a perspective view seen from an upper side andFIG. 5Bis a perspective view seen from a lower side. The flow rate adjustment mechanism8includes the stepping motor60being a drive source, the valve element drive member50, the valve element20, and the valve seat40. The valve element drive member50, the valve element20, and the valve seat40are arranged in this order from the upper direction to the lower direction centered around the support shaft29that extends in the up-down direction along the axis L that runs parallel to the axis L0of the stepping motor60. The valve seat40is circular, and a shaft hole41to which the support shaft29is fixed is formed at a center of the valve seat40. The valve element drive member50and the valve element20are rotatably supported on the support shaft29.

The valve element drive member50is a gear member having a tooth part51formed on an outer peripheral surface of the valve element drive member50, and the tooth part51meshes with the pinion66of the stepping motor60. The rotation of the stepping motor60is decelerated via the pinion66and the tooth part51, and then, transmitted to the valve element drive member50. The valve element drive member50of the present embodiment is a gear member provided with the tooth part51. Therefore, it is not necessary to provide a component for configuring a speed reduction mechanism, so that the number of components of the flow rate adjustment mechanism can be reduced. Therefore, it is advantageous for downsizing the valve device1.

As illustrated inFIG. 5A, the valve element drive member50is formed with an arm part52that protrudes radially outward from a part of the valve element drive member50in the circumferential direction. When the valve element drive member50rotates to reach a predetermined angular position, the arm part52abuts from one side or the other side around the axis L against a rotation restricting part (not illustrated) provided in the rotor61to limit a rotation angle of the valve element drive member50and the valve element20to a predetermined range.

As illustrated inFIG. 5B, the valve element drive member50includes a flat lower end surface501orthogonal to the axis L of the support shaft29. The lower end surface501faces the valve element20. On the lower end surface501, convex parts551,552, and553being fitting parts projecting toward the valve element20, are formed. The convex parts551,552, and553are arranged at unequal intervals along the circumferential direction of the valve element drive member50. Hereinafter, these three convex parts are collectively referred to as “convex parts55”. Among end surfaces of the valve element20, on an upper end surface202facing the valve element drive member50, at positions corresponding to the convex parts55of the valve element drive member50, concave parts251,252, and253being fitting parts into which the convex parts55are fitted, are formed. Hereinafter, these three concave parts are collectively referred to as “concave parts25”. When these plurality of sets of fitting parts (the convex parts55and the concave parts25) are fitted, the valve element20is integrated with the valve element drive member50and rotates in the circumferential direction. In addition, when the plurality of sets of fitting parts are arranged at unequal intervals along the circumferential direction of the valve element drive member50and the valve element20, it is possible to prevent a case where the valve element drive member50and the valve element20are incorrectly assembled. It is noted that convex and concave directions of the convex parts55and the concave parts25may be reversed. In other words, the valve element drive member50may be formed with a concave part, and the valve element20may be formed with a convex part to fit into the concave part of the valve element drive member50.

An outer shape of the valve element20is a circle centered around the axis L. The valve element20includes a flat lower end surface201orthogonal to the axis L of the support shaft29. The lower end surface201faces the valve seat40. The lower end surface201is formed with a cutaway part22cut radially inward from the outer peripheral surface of the valve element20. The cutaway part22is formed at a position spaced apart in the circumferential direction from a flow channel securing groove27described later. Of the concave parts25formed in the valve element20, a concave part251is a through hole that penetrates to a side of the cutaway part22. A distal end part of a convex part551fitted into the concave part251is exposed to the side of the cutaway part22and the distal end part of the convex part551is caulked on the side of the cutaway part22. As a result, the valve element20is fixed, without rattling, to the lower end surface501of the valve element drive member50. Therefore, the valve element drive member50can highly accurately control an angular position of the valve element20.

The valve seat40is arranged below the valve element20and is fitted into the valve seat attachment hole14formed in the base10. The valve seat40is a substantially cylindrical member, and on the upper surface thereof, a valve seat surface42is provided. The valve seat surface42is a circular plane orthogonal to the axis L. The valve seat40is formed with the refrigerant outlet43that penetrates the valve seat40at a position deviated radially outward from the axis L. An upper end of the refrigerant outlet43is an outlet44being an opening part that is provided in the valve seat surface42.

The valve element20is a disk-shaped member and is placed on the valve seat40. The lower end surface201of the valve element20is an abutment surface abutting against the valve seat surface42. Moreover, the upper end surface202of the valve element20is an opposite surface facing an opposite side of the lower end surface201being the abutment surface. When the valve element drive member50is rotated by a driving force of the stepping motor60, the valve element20rotates together with the valve element drive member50, and the lower end surface201(abutment surface) of the valve element20relatively rotates, while sliding with the valve seat surface42, relative to the valve seat surface42. As a result, a state where the outlet44formed in the valve seat surface42is closed by a flat surface part of the lower end surface201of the valve element20and a state where the outlet44communicates with the valve chamber30are switched.

The lower end surface201of the valve element20and the valve seat surface42of the valve seat40are polished to be a flat surface. This enhances a sealing performance of the lower end surface201of the valve element20and the valve seat surface42, and as a result, it is possible to prevent the refrigerant from leaking from a gap between a contact surface between the valve element20and the valve seat surface42. Further, when the valve element drive member50and the valve element20are fixed, the distal end part of the convex part551is caulked by the cutaway part22, and thus, abrasion and deformation caused by caulking work on the lower end surface201of the polished valve element20can be prevented. It is noted that in the present embodiment, both the lower end surface201of the valve element20and the valve seat surface42of the valve seat40are polished; however, even if only one of the surfaces is polished, an equivalent leakage prevention effect is obtained.

FIG. 6Ais a top surface view of the valve element20, andFIG. 6Bis a bottom surface view of the valve element20. The valve element20is formed with five through holes211,212,213,214, and215that penetrate the valve element20in an axis L direction. Hereinafter, these five through holes are collectively referred to as “through holes21” (seeFIG. 6B). Each of the through holes21has a smaller diameter than that of the outlet44formed in the valve seat surface42. The hole diameters of the five through holes21are progressively increased so that the hole diameter of the through hole211is the smallest and the hole diameter of the through hole215is the largest. The valve element20of the present embodiment includes a plurality of through holes21that has different hole diameters. Therefore, when the valve element20is rotated, the flow rate can be adjusted by switching the through hole21that communicates with the outlet44formed in the valve seat surface42. It is noted that the hole diameters of the through holes211,212,213,214, and215can be appropriately changed according to a usage method of the valve device1. For example, the order of the hole diameters of the through holes211,212,213,214, and215may be differed from the above example.

On the lower end surface201of the valve element20, the cutaway part22recessed upward is formed. The cutaway part22is a refrigerant flow channel through which the refrigerant flows. The cutaway part22has a size allowing a whole of the outlet44of the valve seat surface42to be exposed when the valve element20is at a predetermined angular position. That is, the cutaway part22has a larger width in the circumferential direction than the outlet44, and is configured such that the lower end surface201of the valve element20does not contact the outlet44when the valve element20is at a predetermined angular position. When the whole of the outlet44is exposed in the cutaway part22, the flow rate of the refrigerant reaches a maximum flow rate.

On the upper end surface202(opposite surface) of the valve element20, flow channel grooves241,242,243,244, and245are formed which are cut off radially inward from the outer peripheral surface of the valve element20. Hereinafter, these five grooves are collectively referred to as “flow channel grooves24”. Each of the flow channel grooves24is a refrigerant flow channel connected to the through hole21. On the upper end surface202of the valve element20, the concave part252is formed between the flow channel groove241and the flow channel groove242and is in communication with the flow channel groove241and the flow channel groove242in the circumferential direction. Similarly, a concave part253is formed between the flow channel groove244and the flow channel groove245and is in communication with the flow channel groove244and the flow channel groove245in the circumferential direction. As described above, the concave parts252and253are continuous with the flow channel grooves on both sides thereof in the circumferential direction, and thus, a wide space for providing the through hole21is secured.

On the upper end surface202of the valve element20, support surfaces262and263abutting against the lower end surface501of the valve element drive member50are provided on radially outer sides of the concave parts252and253. The support surfaces262and263are provided on an outer peripheral part farthest from the center of the valve element20. The support surfaces262and263are located on the same plane as other parts of the upper end surface202of the valve element20. The support surfaces262and263abut against the lower end surface501of the valve element drive member50to restrict an inclination of the valve element20.

The five through holes21are arranged on an arc having the same diameter with respect to a radial center of the valve element20. A movement trajectory C (seeFIG. 6(b)FIG. 6B) of the through hole21obtained when the valve element20rotates about the axis L passes through a center of the outlet44formed in the valve seat surface42. Further, the five through holes21are located in an approximately middle between the radial center of the valve element20and the outer peripheral edge of the valve element20. Accordingly, it is possible to have a sufficient space on a radially outer side and a radially inner side of the through hole21, and thus, the sealing performance between the valve element20and the valve seat surface42can be enhanced on both sides of the through hole21in the radial direction. In addition, it is possible to have a sufficient space on a radially outer side of the concave parts252and253between the valve element20and the valve element drive member50, and thus, the support surfaces262and263can be provided on the radially outer side of the concave parts252and253. Therefore, the inclination of the valve element20can be prevented and the sealing performance can be enhanced.

The valve element20is made of polyphenylene sulfide resin, and the valve element drive member50is made of nylon resin. Polyphenylene sulfide resin has high moldability and excellent wear resistance. Since the valve element drive member50does not require molding accuracy as high as that of the valve element20, an increase in cost can be suppressed by using an inexpensive nylon resin.

The valve element20rotates about the support shaft29, based on the rotation of the valve element drive member50. That is, the axis L that passes through the center of the support shaft29is a rotation axial line of the valve element20. Further, the circumferential direction centered around the axis L is a moving direction (rotating direction) of the valve element20relative to the valve seat surface42. Hereinafter, the circumferential direction centered around the axis L is referred to as a first direction X. Further, a radial direction centered around the axis L is referred to as a second direction Y. In the present embodiment, to ensure that the refrigerant of the valve chamber30flows out to the outflow pipe4, the valve seat40fitted to the base10is formed with the refrigerant outlet43that penetrates the valve seat40in the axis L direction, and the outflow pipe4is connected to a lower end of the refrigerant outlet43. The valve seat surface42being an upper end surface of the valve seat40is a plane orthogonal to the axis L, and is exposed internally of the valve chamber30. The valve seat surface42is formed with the outlet44being an opening part provided at the upper end of the refrigerant outlet43. It is noted that in the valve device1according to the present embodiment, the valve seat40is attached to a location with which the outflow pipe4is connected, out of the inflow pipe3and the outflow pipe4, but an inflow side and an outflow side may be reversed. That is, the valve seat40may be attached to a location with which the inflow pipe3is connected, and the outlet44may be used as an inlet.

The flow rate adjustment mechanism8controls a rotational position of the valve element20by driving the valve element drive member50to switch the through holes21that communicates with the outlet44so that the flow rate of the fluid (refrigerant) is adjusted. Further, the rotational position of the valve element20is controlled to switch among a flow rate adjustment mode in which the outlet44communicates with any of the through holes21, a maximum flow rate mode in which the valve chamber30and the outlet44communicate without passing through the through hole21, and a supply stop mode in which the outlet44is closed by the valve element20.

The lower end surface201of the valve element20is an abutment surface abutting against the valve seat surface42formed thereon with the outlet44in the axis L direction. In the lower end surface201, lower ends of the five through holes21described above are opened. In the present embodiment, to ensure that the through holes21and the outlet44are in communication even if there is a variation in the rotational position of the valve element20, flow channel securing grooves271,272,273,274, and275being concave parts larger than the hole diameters of the through holes21are formed on the lower end surface201of the valve element20. The flow channel securing groove271,272,273,274, and275are concave parts recessed upward from the lower end surface201. Each of the through holes21opens on the bottom surface of each of the flow channel securing grooves271,272,273,274and275. Hereinafter, these five flow channel securing grooves are collectively referred to as “flow channel securing grooves27” (seeFIG. 6(b)FIG. 6B).

FIG. 7is an explanatory diagram of the through holes21and the flow channel securing grooves27. As illustrated inFIG. 7, the through hole21is arranged at a center in the first direction X (circumferential direction) of the flow channel securing groove27and at a center in the second direction Y (radial direction) of the flow channel securing groove27. In the flow channel securing groove27, a width X1in the first direction X and a width Y1in the second direction Y are larger than the hole diameter of the through hole21. Further, in the flow channel securing groove27, the width X1in the first direction X, which is the moving direction of the valve element20, is smaller than the width Y1in the second direction Y orthogonal to the first direction X. That is, the flow channel securing groove27has a long hole shape elongated in a direction orthogonal to the moving direction of the valve element20(radial direction).

An edge of the flow channel securing groove27includes a straight line part27A located on either side of the through hole21in the first direction X (that is, either side of the through hole21in the circumferential direction). The straight line part27A extends in the second direction Y. Thus, the flow channel securing groove27has a shape in which a circumferential width increases toward a radially outer side. In addition, a radially outer edge and a radially inner edge of the flow channel securing groove27have an arc shape centered around the axis L located at a rotation center of the valve element20.

Thus, as a result of the through hole21being formed at the bottom part of the flow channel securing groove27larger than the hole diameter of the through hole21, a decrease in the flow rate due to the displacement of the rotational position of the valve element20is suppressed. That is, even in a case where the through hole21partially overlaps with the outlet44as a result of the rotational position of the valve element20being displaced from a design location due to a component tolerance or the like, or as long as an overlapping area between the flow channel securing groove27that communicates with the through hole21and the outlet44is larger than a cross-sectional area of the through hole21even if the through hole21does not completely overlap with the outlet44, a refrigerant that has a flow rate corresponding to the hole diameter of the through hole21can be flowed. Therefore, the accuracy of flow rate adjustment by the through hole21can be enhanced.

A depth of the flow channel securing groove27is deeper than the hole diameter of the corresponding through hole21. Therefore, it is designed so that the flow rate passing through the flow channel securing groove27does not fall below the flow rate that passes through the through hole21, and therefore, the flow rate of the through hole21is not limited by the flow channel securing groove27. It is noted that in the present embodiment, the hole diameter of the flow channel securing groove27is constant, but the hole diameter need not be constant. An inner peripheral surface of the flow channel securing groove27may have a shape in which the hole diameter increases as a distance from the through hole21increases. For example, the inner peripheral surface of the flow channel securing groove27can be tapered.

FIG. 8AandFIG. 8Bare explanatory diagrams each illustrating an overlap between the flow channel securing groove27and the outlet44.FIG. 8AandFIG. 8Bschematically illustrate a shape of the flow channel securing groove27of the present embodiment and a shape of a circular flow channel securing groove276identical in width in the first direction X to the flow channel securing groove27. Since the flow channel securing groove27of the present embodiment has a long hole shape in which the width in the second direction Y orthogonal to the first direction X is longer than a dimension in the first direction X, edges on both sides in the first direction X are linear. It is noted that the edges on the both sides of the flow channel securing groove27in the first direction X may not need be linear. For example, it may suffice that the edges on the both sides have a substantially straighter line shape than the edge of the circular flow channel securing groove276, and the edges on the both sides may be a curved line. For example, the flow channel securing groove27may have an oval shape long in the second direction Y. As described above, if the edge in the first direction X is linear or resembles a straight line rather than an arc, an overlapping region of the flow channel securing groove27and the outlet44includes an overlapping region277illustrated by hatching inFIG. 8A. On the other hand, the overlapping area of the circular flow channel securing groove276and the outlet44does not include the overlapping region277illustrated by hatching inFIG. 8AandFIG. 8B. That is, the flow channel securing groove27of the present embodiment has a larger region overlapping with the outlet44than the circular flow channel securing groove276if the flow channel securing groove27coincides in displacement of the rotational position with the outlet44.

Thus, in addition to a shape for ensuring the same overlapping area as the cross sectional area of the through hole21, the flow channel securing groove27of the present embodiment has a smaller width in the first direction X (circumferential direction) than the circular flow channel securing groove276. Therefore, it is possible to more effectively utilize a space of the lower end surface201of the valve element20than a case where the circular flow channel securing groove276is formed, and it is possible to increase the degree of freedom of arranging the flow channel securing groove27and the through hole21. Therefore, the number of flow channel securing grooves27and through holes21that can be formed in the lower end surface201of the valve element20can be maximized. Specifically, it is possible to arrange the flow channel securing grooves27with a sufficient space in the circumferential direction, and thus, the number of flow channel securing grooves27and through holes21that can be arrayed in the circumferential direction can be maximized. Further, the flow channel securing grooves27can be arranged apart from one another in the circumferential direction. Accordingly, the sealing performance among the adjacent flow channel securing grooves27can be improved.

Arcs276A and276B illustrated inFIG. 8Bare movement trajectories of the circular flow channel securing groove276obtained when the valve element20rotates about the axis L. The flow channel securing groove to which the present invention is applied may include, as a region overlapping with the outlet44, a part of a region299(region indicated by hatching inFIG. 8B) defined by a radial straight line centered around the axis L (straight line that overlaps with the straight line part27A), an outer shape of the circular flow channel securing groove276, and the arcs276A and276B indicating the movement trajectory of the circular flow channel securing groove276, and may suffice to have a shape in which the width in the second direction Y is larger than the width in the first direction X. With such a shape, if the displacement in rotational position from the outlet44is the same, an overlap with the outlet44can be made larger than the circular flow channel securing groove276. Therefore, an operation and effect similar to those of the flow channel securing groove27of the present embodiment can be obtained.

In the present embodiment, the displacement of the rotational position of the valve element20due to component tolerances or the like can be kept within approximately eight steps in terms of the number of driving steps of the stepping motor60. Therefore, as a result of simulation of an area that overlaps between the flow channel securing groove27and the outlet44if the rotational position of the valve element20was displaced by eight steps where the valve element20had a diameter of 8 mm, in the circular flow channel securing groove276, if the width in the first direction X of the flow channel securing groove276was 0.36 mm, an area that overlaps between the outlet44and the flow channel securing groove276was made identical to the cross-sectional area of the through hole21. On the other hand, when the shape of the flow channel securing groove27of the present embodiment was adopted, if the width in the first direction X of the flow channel securing groove27was 0.26 mm, an area that overlaps between the outlet44and the flow channel securing groove276was made identical to the cross-sectional area of the through hole21. That is, the flow channel securing groove27of the present embodiment provides a result that the width in the first direction X (circumferential direction) can be reduced.

It is noted that in the present embodiment, the widths of the five flow channel securing grooves27in the first direction X (circumferential direction) are all the same. Specifically, the shape of the flow channel securing groove27was determined in accordance with the flow channel securing groove27that has the largest hole diameter. Here, the width of the flow channel securing groove27in the first direction X (circumferential direction) can be set to a width corresponding to the hole diameter of the corresponding through hole21. That is, the through hole21that has a small hole diameter can be formed in the flow channel securing groove27that has a small circumferential width, and the through hole21that has a large hole diameter can be formed in the flow channel securing groove27that has a large circumferential width. In this way, the space of the lower end surface201of the valve element20can be used effectively, and the number of the flow channel securing grooves27that can be formed in the lower end surface201can be maximized.

Further, in the present embodiment, the center in the second direction Y of the flow channel securing groove27is located near the radial center of the valve element20, but the flow channel securing groove27can be formed at a location where the center in the second direction Y of the flow channel securing groove27is closer to the center of the valve element20than the outer peripheral edge of the valve element20. If the flow channel securing groove27is arranged near the center of the valve element20, a space near the center of the valve element20can be effectively utilized.

In the present embodiment, the five through holes21are provided, but the number of through holes21can be any number equal to or greater than one. Moreover, if a plurality of through holes21are provided, all of the hole diameters may differ and only a part of the hole diameters may differ.

FIG. 9AandFIG. 9Bare cross-sectional views each illustrating an operation of the flow rate adjustment mechanism8.FIG. 9Aillustrates a state of the flow rate adjustment mode in which the refrigerant flows through the through hole21. Further,FIG. 9Billustrates a state of the maximum flow rate mode in which the refrigerant that has the maximum flow rate flows without passing through the through hole21. If the stepping motor60is driven by an external control device, the driving force is transmitted to the valve element drive member50via the pinion66and the tooth part51of the valve element drive member50. Then, if the valve element drive member50rotates in the circumferential direction, the valve element20rotates on the valve seat surface42in the same direction as the valve element drive member50.

The flow rate adjustment mechanism8rotates the valve element20to a rotational position at which the cutaway part22of the valve element20overlaps in the axis L direction with the outlet44of the valve seat surface42, and a rotational position at which the through hole21of the valve element20overlaps in the axis L direction with the outlet44. In the present embodiment, since the through holes21are provided at five locations, there are five rotational positions where the through holes21overlap in the axis L direction with the outlet44.

In the flow rate adjustment mode illustrated inFIG. 9A, the through hole21and the flow channel securing groove27formed in the lower end surface201of the valve element20overlap in the axis L direction with the outlet44. Accordingly, a first flow channel A1from the valve chamber30, via the flow channel groove24, the through hole21, and the flow channel securing groove27, in this order, communicating with the outlet44is formed. In the flow rate adjustment mode, the flow rate of the refrigerant is determined according to the hole diameter of the through hole21. Therefore, the number of modes in the flow rate adjustment mode matches the number of modes according to the number of holes in the through hole21. In the present embodiment, since the five through holes21are formed, the flow rate adjustment mechanism8includes a five-step flow rate adjustment mode, and can adjust the flow rate in five steps.

In the maximum flow rate mode illustrated inFIG. 9B, if the cutaway part22and the outlet44of the valve element20overlap in the axis L direction, a second flow channel A2from the valve chamber30to the outlet44via the cutaway part22is formed. Since the cutaway part22of the present embodiment exposes a whole of the outlet44into the valve chamber30, the second flow channel A2outputs the refrigerant at a maximum flow rate of the valve device1.

The valve device1controls the number of driving steps of the stepping motor60to control the rotational position of the valve element20. An origin position of the valve element20is a position where the arm part52of the valve element drive member50abuts against a rotation restricting part of the rotor61. Thus, the valve element20at the origin position is restricted from rotating toward a side of the rotation restricting part. If the valve element20is at the origin position, a flat surface part being a region where the cutaway part22and the flow channel securing groove27in the lower end surface201of the valve element20are not formed, blocks the outlet44formed in the valve seat surface42. That is, the supply stop mode in which the supply of the refrigerant is stopped, is established.

If the stepping motor60is driven by a predetermined step in a forward rotation direction from the state where the valve element20is at the origin position, the valve element20moves to a position where the through hole211overlaps in the axis L direction with the outlet44. As a result, the flow rate adjustment mode illustrated inFIG. 9Ais established, and the first flow channel A1is formed. In the present embodiment, among the through holes21provided in the valve element20, the through hole211is a penetration part that has the smallest hole diameter. Therefore, the refrigerant flows at the minimum flow rate.

In the flow rate adjustment mode, the through holes211,212,213,214, and215sequentially move to an angle that overlaps in the axis L direction with the outlet44every time the stepping motor60is driven by a predetermined step in the forward rotation direction. As a result, the flow rate adjustment modes are switched. The through holes211,212,213,214, and215, which increase in hole diameter in this order, are sequentially switched to a mode in which a flow rate is large.

When the stepping motor60is driven by a prescribed step further in a forward rotation direction from the state where the through hole215that has the largest diameter overlaps in the axis L direction with the outlet44, the valve element20moves to a position at which the cutaway part22overlaps in the axis L direction with the outlet44. As a result, the maximum flow rate mode illustrated inFIG. 9Bis established, and the second flow channel A2is formed. When the stepping motor60is further driven from this state, the arm part52of the valve element drive member50abuts against the rotation restricting part of the rotor61from a side opposite to the origin position, and the valve element20is restricted from further rotation. Even at this position, the cutaway part22of the valve element20overlaps in the axis L direction with the outlet44. Therefore, the flow rate reaches the maximum flow rate.

OTHER EMBODIMENTS

In the above embodiment, the movement direction of the valve element20is the rotation direction centered around the axis L, but it may be possible to adopt a structure in which the flow rate is adjusted by sliding the valve element20in a predetermined direction.