BLOWING DEVICE AND FLUID CONTROL DEVICE

A fan unit includes a fan case and a fan. The fan case has an intake port and a discharge port. The fan is provided inside the fan case and has a holding plate having a first surface and being rotatably supported; and a plurality of blade members provided upright on the first surface. The fan unit includes a first passage that is connected to the intake port and is defined by an inner surface of the fan case, the first surface of the holding plate, and two adjacent blades; and a second passage that is on a second surface side of the holding plate and is connected to the discharge port. An outer circumferential end section of the holding plate is positioned progressively lower towards the outside in the radial direction and has a skirt shape having a sharp gradient.

TECHNICAL FIELD

The present disclosure relates to an air blower and a fluid controller used for positive airway pressure (PAP) and the like.

BACKGROUND ART

A conventional fluid controller such as a continuous positive airway pressure (CPAP) device (hereafter referred to as CPAP device) is used to treat sleep-related disorders such as obstructive sleep apnea (OSA). The CPAP device includes an air blower with a built-in fan and supplies a mask covering the mouth or the nose of a patient with gas (such as air) under pressure that is higher than the atmospheric pressure. The CPAP device needs to be quiet as it is used while the patient is asleep. A known CPAP device includes a mechanism that reduces the noise of air flowing into the device (refer to, for example, Patent Document 1).

Prior Art Document

BRIEF SUMMARY

Problems that the Disclosure is to Solve

When the flow of air is disturbed in a fan unit, the discharge efficiency of the air blower in the CPAP device or the like may decrease. It is an object of the present disclosure to provide an air blower that efficiently discharges air and a fluid controller.

Means for Solving the Problems

According to one aspect of the present disclosure, an air blower includes a fan case that includes an intake port and a discharge port, a fan arranged in the fan case, in which the fan includes blades and a holding plate, the holding plate includes a first surface on which the blades are arranged and a second surface at a side opposite to the first surface, a first passage connected to the intake port and encompassed by the first surface of the holding plate, an inner surface of the fan case, and two adjacent ones of the blades, and a second passage connected to the discharge port in the holding plate at a side of the second surface. The holding plate includes an outer circumferential end section located outward from the blades. The outer circumferential end section is flared so that the outer circumferential end section extends downward toward an outer side of the holding plate so as to increase inclination. With this structure, air is efficiently discharged.

According to another aspect of the present disclosure, a fluid controller includes the air blower and a controller that controls the air blower. With this structure, the air blower has good discharge efficiency and the controller causes the air blower to discharge necessary air.

According to one aspect of the present disclosure, an air blower that efficiently discharges air and a fluid controller are provided.

DETAILED DESCRIPTION

Embodiments of the present disclosure will now be described below. In the accompanying drawings, elements are illustrated for simplicity and clarity and have not necessarily been drawn to scale. An element may be sized differently from the actual element. Further, an element may be sized differently between drawings. Hatching lines may be omitted from several elements in the cross-sectional views to facilitate understanding.

As shown inFIG. 1, a fluid controller1according to a first embodiment includes a rectangular parallelepiped case10. The case10includes a side surface10ato which a suction panel11is attached. The case10also includes a discharge port12in the side surface10a.The suction panel11is attached to an open portion10bof the case10. The suction panel11includes suction ports11aarranged in a lattice. The suction panel11draws ambient air into the case10. The suction panel11includes, for example, a filter attached to the case10in a removable manner. The fluid controller1discharges the ambient air drawn through the suction ports11aand out of the discharge port12. The attachment position of the suction panel11, and the shape, arrangement, and the like of the suction ports11amay be changed.

As shown inFIG. 2, the fluid controller1is used as, for example, a continuous positive airway pressure (CPAP) device. The fluid controller1is connected to a mask3by a tube2. The mask3covers the nose or the mouth of a patient4. The fluid controller1supplies fluid (such as air) having a desired pressure to the patient4through the tube2and the mask3.

The state of the patient4(such as exhalation) may be determined to control the pressure of gas supplied to the patient4in accordance with the determined state. The fluid controller1estimates, for example, an exhalation state of the patient4wearing the mask3and controls the pressure of the supplied gas in synchronization with the exhalation state. For example, the pressure during inhalation is 1000 Pa, and the pressure during exhalation is 700 Pa. When the patient4is in the exhalation state, the pressure of the supplied gas is lowered to mitigate breathing difficulty of the patient4.

As shown inFIG. 3, the case10of the fluid controller1includes a case body21having an open upper part and a cover member22that closes the opening of the case body21. The case body21includes the discharge port12. The suction panel11is attached to the case body21.

The case body21includes a partitioning portion23. The partitioning portion23has the form of a rectangular frame and includes an open upper part. The partitioning portion23is formed integrally with the case body21. The opening of the partitioning portion23is closed by an inner cover24fixed to the partitioning portion23. The case body21includes an air blowing chamber25surrounded by the partitioning portion23and the inner cover24. The air blowing chamber25accommodates a fan unit31. The case body21also includes a control chamber26located at the side of the air blowing chamber25opposite to the suction panel11. The control chamber26accommodates a control unit32. The control unit32includes a control board and the like and is schematically illustrated having a rectangular parallelepiped shape. The control unit32controls the fan unit31. The fluid controller1, which includes the fan unit31and the control unit32, controls fluid (air).

As shown inFIGS. 5, 6, and 8, a fan case40of the fan unit31includes an intake port40aat an upper portion and a discharge port40bthat projects at a side portion. The fan case40accommodates a fan50having a center axis A1. It is to be appreciated that for the purposes of this disclosure, the center axis A1of the fan50defines radial and axial directions of the fan unit31and its elements

As shown inFIGS. 5, 6, and 8, the fan case40includes a lower case41and an upper case42. The lower case41includes a passage portion41aand a discharge portion41b.The passage portion41ais shaped to be annular. As shown inFIG. 8, the passage portion41ahas a U-shaped cross-section. The discharge portion41bis shaped to extend from the passage portion41ain a predetermined direction, more specifically, in a tangential direction of the annular passage portion41ain the present embodiment. A motor60that drives and rotates the fan50is attached to the inner side of the passage portion41a.The motor60includes a rotary shaft61ato which the fan50is fixed. The width of the passage portion41aaround the rotary shaft61aof the motor60in the radial direction is the same or substantially the same. That is, in the fan case40(lower case41) of the present embodiment, the rotary shaft61aof the motor60is not eccentric to the annular passage portion41a.

As shown inFIG. 8, the motor60includes a motor body61and a fixing plate62. The fixing plate62is shaped to be, for example, circular in a plan view. The fixing plate62is fixed to the motor body61by a screw or the like (not shown). A substantially cylindrical fixing member63is attached to the inner side of the lower case41. An O-ring64serving as an elastic member is arranged between the lower case41, the fixing member63, and the fixing plate62of the motor60. The motor60is supported by the lower case41and the fixing member63by way of the O-ring64.

As shown inFIGS. 5 and 6, the upper case42includes a passage portion42aand a discharge portion42b.The passage portion42ais shaped to be annular and has a central opening serving as the intake port40athrough which air is drawn into the fan case40. The discharge portion42bis shaped to extend from the passage portion42ain a predetermined direction, more specifically, in a tangential direction of the annular passage portion42ain the present embodiment. Guiding walls42cextend from the upper surface of the upper case42. The guiding walls42care each shaped to extend in the radial direction of the upper case42. As shown inFIG. 8, the upper ends of the guiding walls42care formed to be substantially parallel with the inner cover24.

As shown inFIG. 8, the fan50is fixed to the rotary shaft61aof the motor60. The motor60, when the motor body61is supplied with power, drives and rotates the rotary shaft61a,and the rotary shaft61ais rotated integrally with the fan50.

As shown inFIGS. 6 to 8, the fan50includes a holding plate51and blades52. As shown inFIG. 8, the holding plate51is rotationally supported and includes a first surface51aand a second surface51b.The first surface51ais arranged at the upper side of the holding plate51directed toward the intake port40aof the fan case40. The second surface51bis arranged at the lower side of the holding plate51directed toward the motor body61.

The first surface51aof the holding plate51has an inner circumference, which defines a fixing portion51cfixed to the rotary shaft61a,and an outer circumference. The first surface51ais inwardly curved from the fixing portion51cso as to extend downward and radially outward and so that the inclination gradually reduces toward the outer circumference. The outer circumferential side of the first surface51aextends substantially parallel to a plane that is orthogonal to the center axis of the holding plate51. Further, the holding plate51includes an outer circumferential end section51dthat has a flared shape. The first surface51aat the outer circumferential end section51dis a curved surface (rounded surface) that is upwardly bulged to extend downward and radially outward and so that the inclination becomes steep at the outer circumference of the first surface51a.

The second surface51bof the holding plate51has an inner circumference, which defines the fixing portion51c,and an outer circumference. The second surface51bextends from the fixing portion51c,which is fixed to the rotary shaft61a,downward and radially outward and so that the inclination gradually reduces toward the outer circumference. The second surface51bat the outer circumferential side extends substantially parallel to a plane that is orthogonal to the center axis of the holding plate51. The second surface51bat the outer circumferential end section51dof the holding plate51then curves downward and radially outward and has an inclination that becomes steep at the outer circumference of the second surface51b.

The outer circumferential end section51dof the holding plate51becomes thinner toward the distal end at the radially outer side. The second surface51bis curved so that the thickness of the holding plate51from the first surface51adecreases toward the distal end at the outer circumferential end section51d.Preferably, the thickness (width in radial direction) at the distal end of the holding plate51is less than or equal to 1 mm. The thickness is 1 mm in the present embodiment.

As shown inFIGS. 6 to 8, the blades52project upward from the first surface51aof the holding plate51. As shown inFIG. 7, the blades52are radially arranged as viewed in the direction of the center axis A1of the holding plate51. The blades52are arranged so that the center of gravity of the fan50corresponds to the center axis A1.

Specifically, the blades52extend from the central region of the holding plate51toward the outer end of the holding plate51as viewed in the center axis direction of the holding plate51. In the present embodiment, the blades52each extend straight. The proximal end of each blade52(i.e., the end that is closer to the center axis A1of the fan50) is located rotationally forward from the other end (i.e., the end that is farther from the center axis A1of the fan50) in the rotation direction of the fan50(counterclockwise inFIG. 7).

As shown inFIG. 7, the blades52of the fan50include first blades53, second blades54, and third blades55. The first blades53to the third blades55have different lengths in the radial direction. Specifically, each first blade53extends from an inner first radial position of the first surface51aof the holding plate51to the vicinity of the outer circumferential end section51d.Each second blade54extends from a second radial position of the first surface51ato the vicinity of the outer circumferential end section51d,the second radial portion being radially outward from the first radial position. Each third blade55extends from a third radial position of the first surface51ato the vicinity of the outer circumferential end section51d,the third radial position being radially outward from the second radial position. The distal ends of the first blades53to the third blades55at the outer side in the radial direction lie on the same circumference.

In the present embodiment, the first blades53and the second blades54are alternately arranged in the circumferential direction of the holding plate51. The third blades55are arranged between the first blades53and the second blades54.

As shown inFIG. 4, the inner (proximal) ends of the first blades53are located radially inward from the intake port40aof the fan case40to be exposed from the intake port40a.Thus, the inner first radial position of each first blade53is set radially inward from the intake port40aof the fan case40.

As shown inFIG. 8, each first blade53includes a vertex53cbetween an inner end53aand an outer end53bon the first surface51aof the holding plate51. The first blade53becomes higher from the inner end53ato the vertex53cand lower from the vertex53ctoward the outer end53b.FIG. 8shows a cross-section of the fan50in a plane that includes the center axis A1of the fan50and extends through the vertex53c.As shown inFIG. 8, the first blade53is arranged so that the vertex53coverlaps the upper case42in a direction parallel to the rotary shaft61aof the fan50. The upper case42includes the circular intake port40a.Thus, the vertex53cof the first blade53is located radially outward from the open end of the intake port40a.

InFIG. 9, the long-dash short-dash line shows the shape of the second blade54and the long-dash double-short-dash line shows the shape of the third blade55at their inner circumferential ends. The shapes of the second blade54and the third blade55at their outer circumferential ends (i.e., distal ends) conform to the shape of the first blade53.

The fan unit31includes a passage70extending from the intake port40aof the fan case40to the discharge port40bof the fan case40. In the present embodiment, the passage70includes a first passage71connected to the intake port40aof the fan case40and a second passage72connected to the discharge port40bof the fan case40. The passage70also includes a buffer passage73located between the first passage71and the second passage72. The passage70(first passage71, second passage72, and buffer passage73) will now be described in detail.

The area between the first surface51aof the holding plate51and an inner surface42dof the upper case42, which is opposed to the first surface51aof the holding plate51, includes a region where the blades52(first blades53to third blades55) are formed and a region where the blades52(first blades53to third blades55) are not formed. In the present embodiment, the first passage71is defined by a portion of the first surface51aof the holding plate51extending from the first radial position to the third radial position of the blades52, the inner surface42dof the upper case42, and two adjacent blades52in the rotation direction. The first passage71is connected to the intake port40aof the fan case40.

The buffer passage73is defined by outer circumferential end section51dof the holding plate51, where the blades52(first blades53to third blades55) are not formed, and the inner surface42dof the upper case42.

The second passage72extends from the buffer passage73to the discharge port40bof the fan case40. As shown inFIG. 10, between the fan case40(upper case42) and the holding plate51, the distance D1(also referred to as the shortest distance) from the first surface51aof the holding plate51to the inner surface42dof the upper case42, which is opposed to the first surface51aof the holding plate51, decreases toward the outer circumferential end section51dof the holding plate51. The distance D1sets the cross-sectional area and the height of the first passage71.

In the present disclosure, the cross-sectional area of the first passage71at a given point along the first surface51ais determined by the area of a plane that is orthogonal to the first surface51aat the point and includes a line segment extending from the first surface51aof the holding plate51to the upper case42. The plane is obtained from a path of the line segment that is rotated about the center axis of the holding plate. In the present embodiment, the first surface51aof the holding plate51and the inner surface42dof the upper case42are formed so that the cross-sectional area at the proximal end of the first passage71(i.e., the end that is closer to the intake port40a) is greater than the cross-sectional area at the other end of the first passage71(i.e., the end that is closer to the second passage72). However, the first surface51aof the holding plate51and the inner surface42dof the upper case42may be formed so that the cross-sectional area at the end of the first passage71closer to the intake port40ais the same as the cross-sectional area at the end of the first passage71that is closer to the second passage72.

In the present disclosure, the height of the first passage71at a given point along the first surface51ais obtained by dividing the cross-sectional area of the first passage71at the given point by the circumferential length of a circle that passes through the point. The circumference length of the circle that passes through the point is calculated based on the radius at the point (distance between center axis A1of holding plate51to point P1). In the present embodiment, the height of the first passage71has characteristics in which the height of the first passage71changes in a concave manner at the radial positions of the first surface51aof the holding plate51. The concave characteristics will be described further below with reference toFIG. 13.

In the fan case40(upper case42) and the holding plate51, the distance D2(also referred to as the shortest distance) from the first surface51aof the holding plate51to the inner surface42dof the upper case42decreases toward the outer circumferential end section51dof the holding plate51. The distance D2sets the cross-sectional area and the height of the buffer passage73.

In the present disclosure, the cross-sectional area of the buffer passage73at a given point along the first surface51ais determined by the area of a plane that is orthogonal to the first surface51aat the point and includes a line segment extending from the first surface51aof the holding plate51to the upper case42. The plane is obtained from a path of the line segment that is rotated about the center axis of the holding plate. In the present embodiment, the first surface51aof the holding plate51and the inner surface42dof the upper case42are formed so that the cross-sectional area of the buffer passage73is substantially constant or gradually reduced from the intake port40ato the second passage72.

Operation

The operation of the fluid controller1and the fan unit31will now be described. As shown inFIG. 4, the fluid controller1includes the rectangular parallelepiped case10and the fan unit31accommodated in the air blowing chamber25that is surrounded by the partitioning portion23and the inner cover24inside the case10.

Further, as shown inFIG. 6, the fan unit31includes the fan case40and the fan50. The fan case40includes the intake port40aand the discharge port40b.The fan50arranged in the fan case40includes the holding plate51, which includes the first surface51aand is rotationally supported, and the blades52(first blades53to third blades55), which extend from the first surface51aof the holding plate51.

As shown inFIG. 8, the fan unit31includes the passage70extending from the intake port40aof the fan case40to the discharge port40bof the fan case40. The passage70includes the first passage71connected to the intake port40a,the second passage72connected to the discharge port40b,and the buffer passage73located between the first passage71and the second passage72. The region between the first surface51aof the holding plate51and the inner surface42dof the upper case42includes a region where the blades52(first blades53to third blades55) are formed and a region where the blades52(first blades53to third blades55) are not formed. In the present embodiment, the first passage71is the region encompassed by the surface of the first surface51aof the holding plate51that extends from the first radial position to the third radial position, the inner surface42dof the upper case42, and two adjacent blades52.

Further, as shown inFIG. 12A, in the fan unit31of the present embodiment, the holding plate51includes the outer circumferential end section51dthat has a flared shape. The first surface51aat the outer circumferential end section51dis a curved surface (rounded surface) that is upwardly bulged to extend downward and radially outward so that the inclination becomes steep.

A first comparative example of the present embodiment will now be described.FIG. 12Bshows part of the first comparative example of the present embodiment. In a fan unit130of the first comparative example, the surface of a holding plate131at an outer circumferential end section131ais straightly cut away in a cross-section. Further, a radially outward side surface of the outer circumferential end section131aextends parallel to the center axis.

In the first comparative example, the flow along the front surface of the holding plate131changes abruptly. Thus, the pressure at such a portion increases and may deteriorate characteristics or generate a backflow. The generation of a backflow will disturb the flow. The disturbed flow will interfere with the blades and produce noise.

Conversely, in the present embodiment, the outer circumferential end section51dof the holding plate51is flared. This gradually curves the flow so that pressure changes are reduced and characteristic deterioration and backflows are limited. This improves the characteristics.

Further, in the present embodiment, the distance D1from the first surface51aof the holding plate51to the inner surface42dof the fan case40, which is opposed to the first surface51a,is decreased toward the outer circumferential end section51dof the holding plate51in accordance with the radius of that position. With this structure, the air drawn from the intake port40awill increase in flow speed and form a smooth airflow when flowing to the discharge port40bthrough the first passage71. This reduces noise as a result.

The blades52(first blades53to third blades55) extend from the central region of the holding plate51to the outer end of the holding plate51as viewed in the center axis direction of the fan50. The end of each blade52that is closer to the center axis A1of the fan50is located rotationally forward from the other end in the rotation direction of the fan50. The cross-sectional area of the first passage71is substantially constant or gradually reduced from the intake port40ato the second passage72. The fan unit31has characteristics in which the height of the first passage71changes in a concave manner at the radial positions. The fan unit31configured in this manner does not reduce the flow speed of fluid. This restricts the separation of fluid and the generation of swirls, thereby restricting disturbance in the flow of fluid and reducing noise.

If the cross-sectional area of the first passage71increases in the direction in which fluid flows, a force that reduces the speed of the fluid acts on the fluid. As a result, the fluid is more likely to be interfered by the components of a flow passage. This may result in the occurrence of separation effect, which hinders the flow in a single direction, or the formation of a swirl. The separation effect of fluid and the formation of a swirl will lead to flow disturbance or pressure fluctuation that increase the noise caused by the flow. In the present embodiment, the cross-sectional area of the first passage71at the end that is closer to the intake port40ais the same or greater than the cross-sectional area of the first passage71at the end that is closer to the second passage72so that the air entering the intake port40aand flowing via the first passage71to the discharge port40bincreases in speed and forms a smooth airflow. As a result, noise is reduced. This limits disturbance in the flow of fluid and reduces noise.

If the cross-sectional area of the first passage71is gradually reduced, the flow speed of fluid flowing out of the outer ends the blades52(first blades53to third blades55) will be increased. With this structure, when swirls are generated at the outer ends the blades52(first blades53to third blades55), the swirls will flow at a high speed toward the second passage72without interfering with the rearward side of the blades52(first blades53to third blades55) in the rotation direction. This limits disturbance in the flow of fluid and reduces pressure fluctuation thereby reducing noise.

The buffer passage73is the defined by the outer circumferential end section51dof the holding plate51, where the blades52(first blades53to third blades55) are not formed, and the inner surface42dof the upper case42. The first surface51aof the holding plate51and the inner surface42dof the upper case42are formed so that the cross-sectional area of the buffer passage73is substantially constant or gradually reduced from the intake port40atoward the second passage72.

If the cross-sectional area of the buffer passage73increases in the direction in which fluid flows, a force that reduces the speed of the fluid acts on the fluid. This may result in the occurrence of separation effect, which hinders the flow in a single direction, or the formation of a swirl. The separation effect of fluid and the formation of a swirl will lead to flow disturbance or pressure fluctuation that increase the noise caused by the flow. In the present embodiment, the cross-sectional area of the buffer passage73is the same or gradually reduced in the direction in which fluid flows. This restricts the reduction of the flow speed, thereby restricting disturbance in the flow of fluid and reducing noise.

FIG. 14shows the cross-sectional area of the first passage71at each radial position. InFIG. 14, the solid line and black circles show the characteristics of the present embodiment, and the long-dash short-dash line and black triangles show the characteristics of a second comparative example. In the second comparative example, the cross-sectional area of the passage gradually increases from the intake port, and then gradually decreases. In the present embodiment, the cross-sectional area of the first passage71is substantially constant at each radial position as compared with the second comparative example.

FIG. 13shows the height of the first passage71at each radial position. InFIG. 13, the solid line and black circles show the characteristics of the present embodiment, and the long-dash short-dash line and black triangles show the characteristics of the second comparative example. The present embodiment has concave characteristics. The term “concave characteristics” used in the present disclosure indicates, as is clear from the solid line curve inFIG. 13, that the characteristics of the line appearing in the plotted region where the horizontal axis shows radial positions and the vertical axis shows the height of the first passage is a curve that is concave upward.

A loudness level (LPM) relative to pressure (back pressure) was measured in the present embodiment and the second comparative example. The loudness level was determined at a location separated from the intake port40aof the fan unit31by 1 m. In the measurement, flow resistance was 10 cm H2O/30 LPM and the back pressure was changed in accordance with the rotation speed of the fan50. The back pressure was in the pressure range (from 4 cm H2O to 20 cm H2O) required to use the fan unit31and the fluid controller1of the present embodiment as a CPAP device.

The measurement results are shown inFIG. 15. InFIG. 15, the solid line and black circles show the measurement result of the fan unit31of the present embodiment, and the long-dash short-dash line and black triangles show the measurement result of the fan unit of the second comparative example. The fan unit31of the present embodiment reduces the loudness level more than the fan unit of the second comparative example.

As shown inFIG. 4, inside the fluid controller1, air near the fan unit31flows toward the intake port40aof the fan case40and is drawn into the fan case40from the intake port40aas shown by the arrows.

A third comparative example of the present embodiment will now be described.FIG. 11is a partial cross-sectional view of a fluid controller including a fan unit100of the third comparative example. In the third comparative example, a fan110housed in a fan case101includes a holding plate111and blades112extending from the holding plate111. Each blade112has a vertex112alocated radially inward from an intake port101aof the fan case101. The vertex112aprojects out of the fan case101from the intake port101a.

In the third comparative example, when the fan110is rotated, a force applied to air by the blades112of the rotating fan110at the inner side from the intake port101aof the fan case101generates an airflow not only in the downstream direction of the first passage71but also in various directions. When an airflow is generated toward, for example, the intake port40a,the flow of air drawn from the intake port40awill be disturbed. In this manner, when the flow of air is disturbed, noise may increase.

In contrast, with the fan unit31of the present embodiment as shown inFIG. 8, the vertexes53cof the first blades53of the fan50accommodated in the fan case40are located radially outward from the intake port40aof the fan case40and covered by the fan case40(upper case42). When the fan50is rotated, the rotating first blades53applies force to air that is directed downstream in the first passage71. This limits disturbance in the flow of air. Thus, noise is reduced.

FIG. 16shows a sound pressure level (LPM) of the present embodiment and the third comparative example relative to pressure. InFIG. 16, the solid line and black circles show the characteristics of the fan unit31of the present embodiment, and the long-dash short-dash line and black triangles show the characteristics of the fan unit100of the third comparative example shown inFIG. 11. The fan unit31of the present embodiment has a lower sound pressure level than the fan unit100of the third comparative example.

FIG. 17shows flow rate and pressure for the present embodiment and the third comparative example. InFIG. 17, the solid line shows the characteristics of the fan unit31of the present embodiment, and the long-dash short-dash line shows the characteristics of the fan unit100of the third comparative example shown inFIG. 11. The present embodiment has the same characteristics as the third comparative example. Further, the present embodiment has slightly higher pressure at high flow rates (150 LPM). This is assumed to be caused by the following reason. In the third comparative example shown inFIG. 11, when a flow of air toward the intake port40ais generated, air drawn from the intake port40ais disturbed as described above. In contrast, with the fan unit31of the present embodiment, the vertexes53cof the first blades53are covered by the fan case40so that air is efficiently directed downstream in the first passage71. This improves the characteristics of the flow rate and the pressure of the fan unit31.

FIG. 18shows pressure relative to the flow rate for the present embodiment and the first comparative example. InFIG. 18, the solid line shows the characteristics of the present embodiment, and the long-dash short-dash line shows the characteristics of the first comparative example. The characteristics of the present embodiment are improved. The flow rate is changed in accordance with the rotation speed of the fan50. The present embodiment allows the rotation speed of the fan50to be decreased when obtaining the same flow rate. A decrease in the rotation speed of the fan50, that is, a decrease in the rotation speed of the motor body61reduces noise. Thus, at the same flow rate, noise is reduced, that is, quietness is improved.

In the fan unit31of the present embodiment, the outer circumferential end section51dof the holding plate51becomes thinner toward the radially outward distal end. The second surface51bis curved so that the thickness of the holding plate51from the first surface51adecreases toward the distal end at the outer circumferential end section51d.The thickness (width in radial direction) of the distal end of the holding plate51is preferably less than or equal to 1 mm.

As shown inFIG. 12B, if the holding plate131remains thick to the end, a large moment of inertia acts on the holding plate131. Thus, even a slight eccentricity would apply a great force to the rotary shaft that vibrates the rotary shaft. This will deteriorate durability and increase noise. In the present embodiment, the outer circumferential end section is formed to become thinner toward the radially outward distal end. This reduces the moment of inertia to reduce vibration, limit durability deterioration, and reduce noise and the like.

In the fan unit130of the comparative example inFIG. 12B, the end of the holding plate131is thick. This generates secondary swirls between airflows shown by arrows Y11and a rotational flow of the second passage72shown by an arrow Y12that form a complicated flow and produce noise.

In contrast, in the fan unit31of the present embodiment, the outer circumferential end section51dof the holding plate51is formed to become thinner toward the radially outward distal end. This hinders the generation of secondary swirls between an airflow shown by an arrow Y1and flowing from the buffer passage73to the second passage72and a rotational flow of the second passage72shown by an arrow Y2. This reduces flow disturbance and noise.

Further, it is preferred that the noise of a secondary swirl has a frequency greater than or equal to a frequency from where the noise becomes subtly audible (e.g., 8 kHz). When a CPAP device is used as shown inFIG. 2, the fan50is driven at about 10 cm H2O. In this case, the speed of the outer circumferential end section of the fan50is approximately 40 m/s. When the noise frequency of a secondary swirl is greater than or equal to the above range (e.g., 8 kHz), the thickness of the distal end of the holding plate51is preferably set to 1 mm or less.

As described above, the present embodiment has the following advantages.

(1) The fan unit31includes the fan case40and the fan50. The fan case40includes the intake port40aand the discharge port40b.The fan50arranged in the fan case40includes the holding plate51, which includes the first surface51aand is rotationally supported, and the blades52(first blades53to third blades55), which extend from the first surface51aof the holding plate51. The fan unit31includes the first passage71and the second passage72. The first passage71is connected to the intake port40aand encompassed by the inner surface42dof the fan case40, the first surface51aof the holding plate51, and two adjacent blades52. The second passage72is connected to the discharge port40bat the side of the second surface51bof the holding plate51. In the fan unit31, the outer circumferential end section51dof the holding plate51has a flared shape. The first surface51aat the outer circumferential end section51dis a curved surface (rounded surface) that is upwardly bulged to extend downward and radially outward so as to have a steep inclination. This gradually curves the flow thereby reducing pressure changes and limiting the generation of backflows. Thus, air is efficiently discharged.

(2) In the fan unit31, the outer circumferential end section51dof the holding plate51is formed to become thinner toward the radially outward distal end. The second surface51bis curved so that the thickness of the holding plate51from the first surface51adecreases toward the distal end at the outer circumferential end section51d.The thickness (width in radial direction) of the distal end of the holding plate51is preferably less than or equal to 1 mm. This reduces the moment of inertia to reduce vibration, limit durability deterioration, and reduce noise and the like.

(3) In the fan unit31, the outer circumferential end section51dof the holding plate51is formed to become thinner toward the radially outward distal end. This hinders the generation of secondary swirls between an airflow from the buffer passage73to the second passage72and a rotational flow of the second passage72, thereby limiting flow disturbance and reducing noise.

(4) With the fan unit31, the vertexes53cof the first blades53of the fan50accommodated in the fan case40are located radially outward from the intake port40aof the fan case40and covered by the fan case40(upper case42). When the fan50is rotated, a force applied to air by the rotating first blades53is directed downstream in the first passage71. Thus, airflow disturbance is limited. This reduces noise.

(5) With the fan unit31, the vertexes53cof the first blades53are covered by the fan case40so that air is directed downstream in the first passage71. This efficiently discharges air.

(6) The distance D1from the first surface51aof the holding plate51to the inner surface42dof the fan case40that is opposed to the first surface51ais reduced toward the outer circumferential end section51dof the holding plate51. The blades52(first blades53to third blades55) extend from the central region of the holding plate51to the outer end of the holding plate51as viewed in the center axis direction of the fan50. The fan unit31does not reduce the flow speed of fluid. This limits the separation of fluid and the generation of swirls, limits flow disturbance, and reduces noise.

(7) In the fan50, the buffer passage73is defined by the region between the surface of the outer circumferential end section51dof the holding plate51, where the blades52(first blades53to third blades55) are not formed, and the inner surface42dof the upper case42. The first surface51aof the holding plate51and the inner surface42dof the upper case42are formed so that the cross-sectional area of the buffer passage73is substantially constant or gradually reduced from the intake port40ato the second passage72. This limits disturbance in the flow of fluid and reduces noise without decreasing the flow speed of fluid.

The above embodiment may be modified as follows.

In the above embodiment, the shape of the fan50may be modified.

In the above embodiment, the arrangement and structure of the blades52(first blades53to third blades55) may be modified.

At least either one of the first blades53and the second blades54may be successively arranged in the order of, for example, the first blade53, the second blade54, the second blade54, the first blade53, the second blade54, and the like.

Further, the first blade53, the second blade54, and the third blade55may be sequentially arranged in this order in the circumferential direction.

The third blades55may be omitted so that the fan includes the first blades53and the second blades54. Alternatively, the second blades54may be omitted so that the fan includes the first blades53and the third blades55.

The technical aspects that are understood from the above embodiment will now be described.

An air blower including:

a fan case that includes an intake port and a discharge port;

a fan arranged in the fan case, where the fan includes a holding plate that includes a first surface and is rotationally supported and blades that project from the first surface and are arranged in a rotation direction; and

a first passage connected to the intake port and encompassed by an inner surface of the fan case, the first surface of the holding plate, and two adjacent ones of the blades, where

the intake port is circular and extends about a rotary shaft of the fan, and

the blades each include a vertex that is located radially outward from the intake port.

The air blower according to embodiment 1, where

the blades extend from a radially inner end of the holding plate toward an outer end of the holding plate as viewed in a direction of a center axis of the fan, and

in each of the blades, one end that is closer to the center axis of the fan is located frontward from another end in the rotation direction of the fan.

The air blower according to embodiment 1 or 2, where the blades include blades that have different lengths from one end that is closer to a center axis of the fan to another end.

The air blower according to embodiment 3, where

the blades include a first blade and a second blade that is longer in length than the first blade, and

the vertex is a vertex of the first blade.

The air blower according to embodiment 4, where one or more of the second blades are arranged between the first blades in a circumferential direction of the holding plate.

The air blower according to embodiment 4 or 5, where the blades further include a third blade that is shorter in length than the second blade.

A fluid controller including:

the air blower according to any one of embodiments 1 to 7; and

a case that accommodates the air blower, where

the case includes a partitioning portion that accommodates the air blower and an inner case that closes an opening of the partitioning portion,

the air blower is arranged to direct the intake port of the air blower toward the inner case, and

the fan case of the air blower includes guiding walls that extend from an outer circumference of the intake port in a radial direction.

An air blower including:

a fan case that includes an intake port and a discharge port;

a fan arranged in the fan case, where the fan includes blades and a holding plate, and the holding plate includes a first surface on which the blades are arranged and a second surface at a side opposite to the first surface;

a first passage connected to the intake port and encompassed by the first surface of the holding plate, an inner surface of the fan case, and two adjacent ones of the blades; and

a second passage connected to the discharge port, where the second passage is arranged in the holding plate at a side of the second surface, where

the holding plate includes an outer circumferential end section located radially outward from the blades, and

the outer circumferential end section is flared so that the outer circumferential end section extends radially outward and downward so as to have a steep inclination.

The air blower according to embodiment 11, where the outer circumferential end section is reduced in thickness toward a distal end.

The air blower according to embodiment 11 or 12, where the outer circumferential end section has a thickness that is less than or equal to 1 mm.

An air blower including:

a fan case that includes an intake port and a discharge port;

a fan arranged in the fan case, where the fan includes a holding plate that includes a first surface and is rotationally supported and blades that project from the first surface and are arranged in a rotation direction; and

a first passage connected to the intake port and encompassed by an inner surface of the fan case, the first surface of the holding plate, and two adjacent ones of the blades, where

the blades extend from a central region of the holding plate toward an outer end of the holding plate as viewed in a direction of a center axis of the fan, and

a distance from the first surface of the holding plate to an inner surface of the fan case that is opposed to the first surface is decreased from an outer circumferential edge of the intake port to an outer circumferential edge of the holding plate.

The air blower according to embodiment 21, where in each of the blades, one end that is closer to a center axis of the fan is located frontward from another end in the rotation direction of the fan.

The air blower according to embodiment 21 or 22, where the blades include blades that have different lengths from one end that is closer to a center axis of the fan to another end.

The air blower according to embodiment 23, where the blades include a first blade and a second blade that is shorter in length less than the first blade.

The air blower according to embodiment 24, where the blades further include a third blade that is shorter in length less than the second blade.

An air blower including:

a fan case that includes an intake port and a discharge port;

a fan arranged in the fan case, where the fan includes a holding plate that includes a first surface and is rotationally supported and blades that project from the first surface and are arranged in a rotation direction; and

a first passage connected to the intake port and encompassed by an inner surface of the fan case, the first surface of the holding plate, and two adjacent ones the blades, where

the blades extend from a central region of the holding plate toward an outer end of the holding plate as viewed in a direction of a center axis of the fan,

a distance from the first surface of the holding plate to an inner surface of the fan case that is opposed to the first surface is such that the distance at an outer circumferential edge of the intake port is greater than the distance at an outer circumferential edge of the holding plate,

the first passage includes a narrowed portion, and

the distance at the narrowed portion is less than the distance at a position adjacent to the narrowed portion.

The air blower according to any one of embodiments 21 to 26, where when a cross-sectional area is an area of an annular circumferential surface formed by a path obtained when rotating a line segment that is orthogonal to the first surface of the holding plate and extends from the first surface to the inner surface of the fan case about a rotary shaft of the fan, the cross-sectional area at the central region of the holding plate is the same or greater than the cross-sectional area at the outer end of the holding plate.

The air blower according to any one of embodiments 21 to 26, where

when dividing an area of an annular circumferential surface formed by a path obtained when rotating a line segment that is orthogonal to the first surface at a point on the first surface of the holding plate and extends from the first surface to the inner surface of the fan case about a rotary shaft of the fan by a circumferential length of a circle passing through the point to obtain a value that is a height of the first passage at the point, the height of the first passage at a given radial position on the first surface has concave characteristics from one end to another end.

A fluid controller including:

the air blower according to any one of embodiments 21 to 28; and

a controller that controls the air blower.