JP2004332724A - Fan impeller and fan motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable, compact and high-performance centrifugal fan to cool electronic components. <P>SOLUTION: In a cantilever type impeller 1 to be used in an centrifugal fan motor having lower end wall constituting parts 2 and 12 in which wall surfaces to block air flow in the axial direction are formed on one end part of the direction of a rotary shaft and an opening part 9 is formed on the other end part in the rotation-axial direction, the diameter 2r of an outer circumferential part of an impeller blade 3 is set to be smaller than the length h in the rotation-axial direction of the impeller 1. Air losses on the wall surface on the other end part of the impeller can be degraded when air flow sucked from the opening part 9 of the impeller is extruded in the outer circumferential direction of the impeller blade 3, and the cooling performance of high efficiency corresponding to the motor performance can be realized thereby. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cooling fan motor and an impeller used for electronic devices and the like, and more particularly, to a fan motor that requires a high static pressure and a high air flow, and a cantilevered impeller used for the fan motor.

A plan view of a conventional centrifugal fan motor 8, a longitudinal sectional view related to X ₁ -O ₁ -Y ₁ -Z ₁ line 8 in FIG. The centrifugal fan motor includes a motor unit 104 that generates a rotational driving force, an impeller unit 101 that generates an airflow, and a housing 106. Note that this centrifugal fan motor uses O1 in FIG. 8 as a rotation axis.
The impeller unit 101 is arranged on the outer peripheral side of the motor unit 104, and includes a lower end wall 102 and wings 103. The lower end wall 102 is an annular plate member arranged around the lower part in the axial direction of the motor part 104, and its plane faces in the axial direction. The lower end of the wing 103 is fixed to an outer peripheral portion of the lower end wall 102. The wing 103 has a so-called cantilever structure supported only by the lower end wall 102. With the forward rotation of the motor unit 104, blade 103 produces a direction of air flow arrows B _1. In the form of drawn into the air stream, resulting in the direction of the intake air flow arrow A ₁ from the intake port 108, in the form of other extruded into the air flow B _1, the exhaust flow is generated in the direction of arrow C _1.
Assuming that the outer diameter of the wing 103 is 2r ₁ and the length in the axial direction is h ₁ , the shape of the impeller 101 of the centrifugal fan used for cooling conventional electronic devices and the like has a wing diameter of 2r ₁ . tended to increase the length h _1. This is because although space saving in the axial direction is the object, was further object also the rotational peripheral speed airflow and static pressure increase in the exhaust flow C ₁ by improving the wing 103. Therefore, in a conventional centrifugal fan having a cantilever impeller in a cooling application of an electronic device or the like directly related to the present invention, the impeller has a thin shape having a relationship of h ₁ ≦ 2r ₁ .

Such a conventional centrifugal fan, since the intake air flow A ₁ shown in FIG. 9 pushes down the air flow B _1, air flow B ₁ represents hits the lower end wall 102, a large windage loss between the wall has occurred. This is because, considering the wind speed distribution on the rotation axis of the impeller unit 101, it is expected that the wind speed of the air flow in the impeller to be sucked will be maximum on the upper surface of the impeller lower end wall 102. Due to the windage loss, the flow rate of the fan decreased, and only a cooling efficiency lower than the inherent performance of the fan motor could be realized.
On the other hand, in recent years, the miniaturization and portability of electronic devices have advanced, and other devices such as mobile phones and mobile personal computers have been required to be further miniaturized. On the other hand, as the degree of integration of electronic circuits has increased and the processing speed has also increased, the total heat generation of LSI chips and built-in electronic circuits is on the rise, and smaller fan motors with higher cooling efficiency are required. Had been.
Accordingly, it is an object of the present invention to provide an ultra-small, high-cooling-efficiency fan motor that can be applied to an ultra-small device such as a mobile phone, and an impeller used for the fan motor. It is another object of the present invention to provide a fan motor which achieves a maximum cooling effect with a minimum suction port area, and an impeller used therefor.

  In order to achieve the object, a fan impeller according to the present invention is a cantilever impeller used for a centrifugal fan motor for cooling portable electronic devices or small devices, and a driving force from a motor unit. Is input, a lower end wall forming part that forms a wall perpendicular to the direction of the rotation axis fixed corresponding to the rotating force transmitting part, and a circumferential direction on the wall surface of the lower end wall forming part. And an impeller blade composed of a plurality of blades extending in the rotation axis direction. When the fan impeller rotates, an airflow in the axial direction flows from the opening on the upper end side of the impeller blade toward the wall surface. When the diameter of the outer peripheral portion of the impeller blade is 2r and the length in the rotation axis direction is h, 2r ≦ h and r <12.5 mm. In this fan impeller, when a driving force is input from the motor unit to the rotational force transmitting unit, the lower end wall forming unit and the impeller blades rotate together with the rotational force transmitting unit. Then, the airflow in the axial direction flows from the opening on the upper end side of the impeller blade toward the wall surface perpendicular to the rotation axis direction of the lower wall component, and then the airflow collides with the wall surface and changes its direction. Since 2r ≦ h, wind loss on the wall surface of the lower end wall constituting portion is reduced and cooling efficiency is improved as compared with the conventional centrifugal fan.

Further, the fan impeller according to the present invention is a cantilever type impeller used for a centrifugal fan motor for cooling a portable electronic device or a small device, and a rotational force transmission to which a driving force from a motor unit is input. Part, a lower end wall constituting part corresponding to the rotational force transmitting part and forming a wall perpendicular to the direction of the rotating shaft, and a rotating shaft arranged circumferentially on the wall surface of the lower end wall constituting part. And an impeller wing comprising a plurality of wings extending in the direction. When the fan impeller rotates, the airflow in the axial direction flows from the opening at the upper end side of the impeller blade toward the wall surface perpendicular to the rotation axis direction of the lower wall component. Assuming that the outer peripheral diameter of the impeller blade is 2r and the length in the rotation axis direction is h, 2πrh = απr ² for the parameter α.
4 ≦ α ≦ 40
And r ≦ 12.5 mm. Since 4 ≦ α, a sufficient decrease in the air flow velocity occurs on the wall surface of the lower wall portion. Therefore, windage loss on the wall surface of the lower wall portion can be further reduced, and a more efficient centrifugal fan can be realized. Further, since α ≦ 40, the shape of the impeller becomes sufficiently short in the axial direction, and stable rotation with little run-out can be realized even with a cantilever type.

Further, the fan impeller according to the present invention is a cantilever type impeller used for a centrifugal fan motor for cooling portable electronic equipment or a small device, and a rotational force transmission to which a driving force from a motor unit is input. Part, a lower end wall constituting part corresponding to the rotational force transmitting part and forming a wall perpendicular to the direction of the rotating shaft, and a rotating shaft arranged circumferentially on the wall surface of the lower end wall constituting part. And an impeller wing comprising a plurality of wings extending in the direction. When the fan impeller rotates, the airflow in the axial direction flows from the opening on the upper end side of the impeller blade toward the wall surface perpendicular to the rotation axis direction of the lower wall component. Assuming that the outer peripheral diameter of the impeller blade is 2r and the length in the rotation axis direction is h, 2πrh = απr ² for the parameter α.
5 ≦ α ≦ 35
And r ≦ 12.5 mm. Since 5 ≦ α, a sufficient decrease in the air flow velocity occurs on the wall surface of the lower end wall constituting portion. Therefore, windage loss on the wall surface of the lower wall portion can be further reduced, and a more efficient centrifugal fan can be realized. Further, since α ≦ 35, the shape of the impeller becomes sufficiently short in the axial direction, and it is possible to realize more stable rotation with less runout even in a cantilever type.

In addition, the fan impeller according to the present invention is a cantilever impeller used for a centrifugal fan motor for cooling portable electronic equipment or a small device, and a rotational force to which a driving force from a motor unit is input. A transmitting portion, a lower end wall forming portion that forms a wall surface perpendicular to the direction of the rotation axis fixed corresponding to the rotational force transmitting portion, and a rotation arranged and circumferentially arranged on the wall surface of the lower end wall forming portion; And an impeller blade formed of a plurality of blades extending in the axial direction. When the fan impeller rotates, an airflow in the axial direction flows from the opening on the upper end side of the impeller blade toward the wall surface. Assuming that the outer diameter of the impeller blade is 2r, the length in the rotation axis direction is h, the number of impeller blades is Z, and the thickness of the blade is d, 2πrεh = βπr ² for the parameter β.
3 ≦ β ≦ 30
Where ε = (2πr−Zd) / 2πr
And 2r ≦ h, r ≦ 12.5 mm. Since 3 ≦ β, a sufficient decrease in the air flow velocity occurs on the wall surface of the lower end wall constituting portion. Therefore, windage loss on the wall surface of the lower end wall portion can be further reduced, and even when the impeller blade outer diameter 2r is small and the total cross-sectional area of the cylindrical surface of the impeller blade cannot be ignored, an efficient centrifugal fan can be used. Can be realized. Further, since β ≦ 30, the shape of the impeller is sufficiently shortened in the axial direction, and stable rotation with little run-out can be realized even with a cantilever type.

In the present invention, it is preferable that the diameter 2r of the cantilever type impeller is 12.5 mm or less. Still more preferably, r is 5 mm or less. This is because this fan impeller needs to be built in a portable electronic device.
In the present invention, a fan motor having these cantilevered impellers is configured.
Further, the present invention is characterized in that in the fan motor having these cantilevered impellers, k <100 mm, where k is a total axial length of the motor and the impeller. In addition, it is preferable that k <70 mm. This is because this fan impeller needs to be built in a portable electronic device or the like.
In the present invention, a fan motor having these cantilevered impellers, wherein the motor unit is constituted by a rotating unit and a fixed unit, and is arranged in a direction of a rotating shaft that rotatably holds the rotating unit and the fixed unit. It has a pair of bearings, sliding bearings, or fluid dynamic pressure bearings arranged, and when the length between both ends in the axial direction of the bearings is m, 0.5m <h. Since h is larger than 0.5 m, it is possible to suppress a loss (windage loss) that occurs when the air current collides with the wall surface of the lower wall portion. As a result, a highly efficient fan motor can be realized. In the present invention, more preferably, h is larger than m, and further preferably, h is larger than 1.5 m. In this case, since the impeller length is further increased, it is possible to further suppress windage loss that occurs when the airflow hits the wall surface of the lower end wall component.

Further, according to the present invention, a fan motor having these cantilevered impellers, wherein the motor portion is constituted by a rotating portion and a fixed portion, and is arranged in a rotation axis direction for rotatably holding the rotating portion and the fixed portion. It has a pair of bearings, sliding bearings, or fluid dynamic pressure bearings arranged, where m> h / 5, where m is the length between both ends in the axial direction of the bearings. Since m is larger than h / 5, the so-called bearing span becomes large, and the rotation of the cantilever impeller can be reliably held on the motor side. As a result, the rotational stability of the fan impeller is improved, and loss due to vibration of the tip of the cantilevered impeller can be minimized. As a result, a highly efficient fan motor can be realized. In addition, in the present invention, more preferably, m is greater than h / 4, and even more preferably, m is greater than h / 3. As a result, the bearing span is further increased, and the rotation of the cantilever type impeller can be held more stably.
Further, according to the present invention, there is provided a fan motor having these cantilevered impellers, wherein the motor unit includes a rotating unit and a fixed unit, and is arranged in an axial direction that rotatably holds the rotating unit and the fixed unit. Wherein the fixed portion includes a stator, and the pair of bearing portions are arranged at positions sandwiching the stator in the rotation axis direction. Since the pair of bearing portions are arranged on both sides in the axial direction of the stator, it is possible to increase the bearing span to a width close to the maximum width of the motor in the rotation axis direction. As a result, it is possible to stably hold the rotational vibration of the cantilever type impeller, which is the load of the motor, and to realize an efficient fan motor with less loss due to vibration.

Further, according to the present invention, in a fan motor having these cantilevered impellers, the motor unit is configured by a rotating unit and a fixed unit, and a sliding bearing unit that rotatably holds the rotating unit and the fixed unit or It has a fluid dynamic pressure bearing portion, the fixed portion includes a stator, and the sliding bearing portion or the fluid dynamic pressure bearing portion has both ends in the axial direction arranged on the rotation axis side outside both ends in the axial direction of the stator. It is characterized by having. Both ends of the sliding bearing portion or the fluid dynamic pressure bearing portion in the axial direction are arranged outside the both axial ends of the stator in the rotation axis direction. As a result, the bearing span becomes the maximum width of the motor in the rotation axis direction. It is possible to enlarge to a width close to. As a result, it is possible to stably hold the rotational vibration of the cantilever type impeller, which is the load of the motor, and to realize an efficient fan motor with less loss due to vibration.
In addition, in the present invention, a fan motor having these cantilevered impellers, wherein the motor unit includes a rotating unit and a fixed unit, and includes a bearing unit that rotatably holds the rotating unit and the fixed unit. The end face of the end face of the fan impeller in the direction of the rotation axis may be fixed to the bearing part directly or via a bearing holder. For this reason, the fan motor is downsized in the axial direction.

According to the present invention, there is provided a fan motor having these cantilevered impellers, wherein the motor section includes a rotating section and a fixed section, and has a bearing section for rotatably holding the rotating section and the fixed section. The lower end wall constituting portion of the fan impeller simultaneously constitutes a part of the upper wall surface of the motor portion. Since the wall at the boundary between the impeller section and the motor section is common, the number of parts is reduced and the fan motor is downsized in the axial direction. As a result, it is possible to realize a small-sized fan motor with low member cost and small manufacturing cost.
Further, according to the present invention, a fan motor having these cantilevered impellers, wherein the motor portion is constituted by a rotating portion and a fixed portion, and is arranged in a rotation axis direction for rotatably holding the rotating portion and the fixed portion. The fixed portion includes a pair of bearing portions, the fixed portion includes a shaft, the inner ring of the pair of bearing portions is fixed to the shaft, the rotating portion includes a rotor holder, and the rotor holder includes the pair of bearing portions. The outer ring of each of the bearing portions is fixed. Since the outer ring of the bearing is fixed to the rotor holder and the inner ring is fixed to the shaft, the support of the rotating portion is stabilized.

Further, according to the present invention, in a fan motor having these cantilevered impellers, the motor unit is constituted by a rotating unit and a fixed unit, and is arranged in a direction of a rotation axis that rotatably holds the rotating unit and the fixed unit. It has a bearing part arranged, the rotating part includes a rotor holder, and the rotating force transmitting part is fixed so as to cover the peripheral surface of the rotor holder. As described above, since the rotational force transmitting portion of the fan impeller has a large contact area with the rotor holder, the motor rotational driving force generated from the rotor magnet fixedly arranged on the inner peripheral surface of the rotor holder is directly transmitted to the impeller portion, As a result, stability during rotation of the fan impeller is further improved, and loss due to vibration is reduced.
In addition, according to the present invention, a fan motor having these cantilevered impellers, wherein the motor unit includes a rotating unit and a fixed unit, and a rotating shaft direction that rotatably holds the rotating unit and the fixed unit. , Wherein the rotational force transmitting portion covers a peripheral outer peripheral surface of the rotating portion. As described above, since the rotational force transmitting portion of the fan impeller further increases the contact area with the rotor holder, the motor rotational driving force generated from the rotor magnet fixedly arranged on the inner peripheral surface of the rotor holder is directly transmitted to the impeller portion. As a result, stability during rotation of the fan impeller is further improved, and as a result, loss due to vibration is reduced.

In the present invention, a fan motor having these cantilevered impellers, wherein the motor unit is constituted by a rotating unit and a fixed unit, and is arranged in a direction of a rotating shaft that rotatably holds the rotating unit and the fixed unit. The rotating portion includes a magnetic rotor holder, a rotor magnet is fixedly attached to an inner peripheral surface of the rotor holder, and the rotational force transmitting portion covers a peripheral outer peripheral surface of the rotating portion. It is characterized by being fixed in an aspect. As described above, the rotational force transmitting portion of the fan impeller has a larger contact area with the rotor holder and is reinforced by the magnetic rotor holder, so that the fan impeller is fixedly arranged on the inner peripheral surface of the rotor holder. The motor rotation driving force generated by the rotor magnet is directly transmitted to the impeller section, and as a result, the stability of the fan impeller during rotation is further improved, and the loss due to vibration is further reduced.
According to the present invention, there is provided a fan motor having these cantilevered impellers, wherein the motor unit includes a rotating unit and a fixed unit, and a rotating shaft direction that rotatably holds the rotating unit and the fixed unit. The fixed portion includes a bracket and a stator, the rotating portion includes a shaft, a shaft holding portion to which one end of the shaft is fixed, and an outer diameter end portion of the shaft holding portion. And a rotor magnet fixed integrally or by adhesion or pressure welding or welding, and a rotor magnet fixedly held on the inner peripheral side of the rotor holder, and the inner peripheral side of the rotor magnet has a minute gap on the outer peripheral side of the stator. It is characterized in that it has a structure facing in the radial direction through the intermediary. Thus, the cantilever impeller is efficiently held by the so-called shaft rotation motor, and a simpler fan motor structure is realized.

In addition, according to the present invention, a fan motor having these cantilevered impellers, wherein the motor unit includes a rotating unit and a fixed unit, and a rotating shaft that rotatably holds the rotating unit and the fixed unit. The bearing has a bracket and a stator, the rotating part has a shaft, a shaft holding part to which one end of the shaft is fixed, and an outer diameter end of the shaft holding part. And a rotor magnet fixed integrally or by adhesion or pressure welding or welding, and a rotor magnet fixedly held on the inner peripheral side of the rotor holder, and the inner peripheral side of the rotor magnet has a minute gap on the outer peripheral side of the stator. And a structure in which the motor shaft holding portion is integrally formed so as to also serve as the lower end wall constituting portion of the impeller. . This makes it possible to integrate a part of the rotor part of the so-called shaft rotation motor and a part of the impeller, thereby realizing a more simple fan motor structure.
Further, according to the present invention, in these cantilevered impellers or the cantilevered impellers used for these fan motors, a part or all of an inner peripheral angle portion on an upper end side in a rotation axis direction of the impeller blades is formed into an arc shape or an arc shape. It is characterized by being chamfered with an approximate curve shape. By forming an arc-shaped chamfer on the inner peripheral corner of the upper end side of the impeller blades in the rotation axis direction, the intake air flow to the impeller flows more smoothly, and at the same time, unnecessary turbulence is suppressed. As a result, a fan impeller with good cooling efficiency and a fan motor using the same can be realized.

Further, in the present invention, the cantilever type impeller or the cantilever type impeller used for these fan motors, wherein the impeller is a liquid crystal polymer, a carbon fiber reinforced liquid crystal polymer, a glass fiber reinforced liquid crystal polymer, a carbon fiber and a glass fiber An impeller or a fan motor with an impeller, part or all of which is made of reinforced liquid crystal polymer, soft iron, stainless steel, aluminum, or ceramic. As a result, the fan impeller can achieve weight reduction and size reduction while securing sufficient rigidity and airflow generation performance.
According to the present invention, there is provided a fan motor having a cantilevered impeller, where n is 5,000 rpm, and preferably n is 10,000 rpm, where n is the number of revolutions of the motor. In the fan motor having a fan impeller long in the rotation axis direction according to the present invention, high static pressure and high efficiency cooling performance can be realized only by such high-speed rotation.

  In the fan impeller and the fan motor according to the present invention, the impeller, which is longer in the axial direction than the conventional centrifugal fan, is rotated at a high speed, so that the windage loss on the wall of the lower end wall constituting portion is reduced, and the unprecedented static Pressure fan motor was realized. As a result, it has become possible to cool small-sized electronic devices and electronic devices with high density with several times the efficiency of conventional devices.

FIG. 1 is a plan view of a centrifugal fan motor according to one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view taken along line XOYZ of FIG. The vertical direction in FIG. 2 is the direction of the rotation axis of the centrifugal fan motor. In the following description, “upper side” and “lower side” are defined according to FIG. It does not limit the actual mounting posture.
This fan motor includes an impeller unit 1, a motor unit 4, and a housing 6. The impeller unit 1 and the motor unit 4 are connected side by side in the housing 6 in the axial direction. The centrifugal fan motor has a rotation axis of 0 in FIG.
FIG. 3 shows a perspective view of the impeller unit 1. As is apparent from this figure, the impeller unit 1 is a cantilever type impeller used for a centrifugal fan motor, and a rotational force transmitting unit 5 to which a driving force from a motor unit 4 is input and a lower end wall fixed thereto. It comprises a component part 2 and an impeller blade 3 composed of a plurality of blades arranged in the circumferential direction on the wall surface of the lower end wall component part 2 and extending in the rotation axis direction. The impeller blade 3 is supported in a cantilever manner. Specifically, the lower end is fixed to the lower end wall constituting part 2, but the upper end is not supported by anything. That is, the “lower end” and “upper end” of the impeller blade 3 here are synonymous with “fixed end” and “free end” of the impeller blade 3. An opening 9 which is a circular space is provided between upper ends of the plurality of blades of the impeller blade 3. When the impeller unit 1 rotates, the airflow in the axial direction flows from the opening 9 on the upper end side of the impeller blade 3 toward the upper end surface of the lower wall component 2. In this embodiment, the lower end wall constituting portion 2 is a disk-shaped member whose plane is oriented in the direction of the rotation axis. The upper surface of the lower end wall constituting portion 2 constitutes a lower end side wall surface of the impeller blade 3 and has a function of blocking an airflow in the axial direction. As shown in FIG. 2, an annular connecting portion 10 that bundles and reinforces the impeller blades 3 is provided on an outer peripheral portion of an upper end of the impeller blades 3. The housing 6 surrounds the outer periphery and the lower end of the impeller unit 1 and the motor unit 4, and has an upper intake port 6a and a lateral exhaust port 6b. A fixed portion of the motor unit 4 is fixed or integrally formed on the lower end surface of the housing 6.

The rotating force transmitting unit 5 is connected to the rotor of the motor unit 4, and the plurality of impeller blades 3 extending in the axial direction corresponding to the rotation of the motor generates the airflow B, thereby realizing the air blowing function. The airflow B induces the intake airflow A from the intake port 6a of the housing 6 and the impeller opening 9, and consequently generates airflows A, B, and C, and the airflow C is covered by the exhaust port 6b of the housing 6. It is led to a cooling body (not shown).
In the centrifugal fan motor according to the present invention, as compared with the conventional centrifugal fan motor shown in FIG. 8, the outer diameter 2r of the impeller blade 3 of the impeller unit 1 is longer than the length of the impeller unit 1 (exhaust flow can be generated). The length of the impeller blade 3 in the axial direction, more specifically, the length in the axial direction of the portion between the upper surface of the lower end wall constituting portion 2 and the lower surface of the annular connecting portion 10) is longer than h. . In addition, the fan motor according to the present invention enables a portable electronic device or a small device to be efficiently cooled by a high static pressure, and is characterized by r ≦ 12.5 mm.
If the axial length h of the impeller unit 1 is made longer than the outer diameter 2r of the impeller blade 3, the intake air flow A generated by the air flow B in the rotation outer peripheral direction by the impeller blade 3 will have a lower end wall configuration of the impeller unit 1. By the time the air reaches the airflow section B, the airflow B can be smoothly changed before reaching the area 2, and the wind speed on the upper surface of the lower end wall configuration section 2 can be reduced.

Considering the flow velocity distribution of the air flow on the axis of the impeller unit 1, when h becomes long, the maximum point of the flow velocity moves on the axis inside the impeller, and the flow velocity of the air flow on the upper surface of the lower end wall constituting unit 2 becomes smaller than that of the conventional centrifugal fan. As a result, it can be expected that the windage loss on the upper surface of the lower end wall constituting part 2 is reduced. In this case, a point to be noted is where the maximum wind speed point is located on the axis in the flow velocity distribution of the air flow on the axis of the impeller unit 1.
In the conventional centrifugal fan used for cooling the electronic device, it is considered that the maximum point of the flow velocity did not appear, and the flow velocity of the air flow was maximized at the upper end surface of the lower end wall component 2. On the other hand, the relationship between the outer diameter 2r of the impeller blade 3 of the impeller section 1 and the length h of the impeller section is as follows.
2r ≦ h (Equation 1)
When the rotation speed of the fan is set to 5000 rpm or more, the maximum point of the flow velocity appears on the axis line inside the impeller, and it is considered that the air flow velocity does not become the maximum on the upper surface of the lower end wall component 2. As a result, as compared with the conventional centrifugal fan, the windage loss on the upper surface of the lower end wall constituting portion 2 was reduced, and a fan having a higher static pressure and higher cooling efficiency than the conventional centrifugal fan was realized. In particular, when r <12.5 mm, a fan with high cooling efficiency was realized.

One factor relating to whether or not this maximum wind speed point appears on the impeller axis, and if so, where on the axis, is the shape of the impeller section. In the present invention, the airflow inflow area into the impeller section 1 (the cross-sectional area of a cross section perpendicular to the axis at the upper end of the impeller section: πr ² ) and the airflow outflow area pushed out by the impeller blades 3 (the impeller blades 3 in the impeller section reduce the airflow). The relationship with the effective aspect that contributes to extrusion: 2πrh) is
2πrh = απr ² (Equation 2)
4 ≦ α ≦ 40 (Equation 3)
It was found that the airflow velocity at the upper surface of the lower end wall constituting portion 2 did not become maximum, and the air flow at the impeller was performed efficiently. As a result, a high-efficiency fan motor with less windage loss than a conventional centrifugal fan was realized.
Even if α> 40, it is considered that the airflow velocity does not become the maximum on the upper surface of the lower end wall constituting portion 2. However, when α is increased, the impeller shape becomes longer in the axial direction, and the cantilever type realizes stable rotation. Becomes difficult. As a result, the loss due to the vibration of the impeller increases, and as a result, the cooling efficiency of the fan decreases.

And more practically,
5 ≦ α ≦ 35 (Equation 4)
It is desirable that
At 5 ≦ α, the maximum point of the flow velocity appears on the axis line inside the impeller and at a position relatively far from the lower end wall component 2, and accordingly, a sufficient decrease in the air flow velocity occurs on the upper surface of the lower end wall component 2. Is considered to have occurred. Therefore, the windage loss on the upper surface of the lower wall component 2 can be further reduced, and a more efficient centrifugal fan can be realized.
On the other hand, since α ≦ 35, the shape of the impeller is shortened in the axial direction, so that more stable rotation can be realized with the cantilever type. As a result, the impeller vibration was further reduced, and a fan motor with higher cooling efficiency was realized.
The comparison between the airflow inflow area of the impeller unit 1 and the airflow outflow area pushed out by the impeller blades 3 indicates that the outer peripheral area of the impeller: 2πrh is the cross-sectional area of the cylindrical surface around the axis of the impeller blades: dh (where This is applied to a case where d is sufficiently large with respect to the sum of the blade thicknesses: dhZ (where Z is the number of impeller blades). However, when the outer diameter 2r of the impeller blade becomes small and the total cross-sectional area of the cylindrical surface of the impeller blade 3 cannot be ignored, it is necessary to consider the porosity ε of the following equation.

ε = (2πr−Zd) / 2πr (Equation 5)
That is, in this case, in the present invention, the effective airflow outflow area pushed out by the impeller blades 3 is 2πrεh.
2πrεh = βπr ² (Equation 6)
3 ≦ β ≦ 30 (Equation 7)
When, the airflow velocity at the upper end surface of the lower end wall constituting portion 2 is not maximized, and it is clear that the static pressure is higher and the cooling efficiency is higher. As a result, a high-efficiency fan motor with less windage loss than a conventional centrifugal fan was realized.
Here, the reason for setting 3 ≦ β is that when β is equal to or less than this value, the airflow velocity becomes maximum on the upper surface of the lower end wall constituting portion 2. Since it occurs on the upper surface, the cooling efficiency of the fan decreases. On the other hand, the reason for β ≦ 30 is that when β is greater than or equal to this value, the airflow velocity does not become maximum on the upper surface of the lower end wall forming part 2, but when β becomes large, the impeller shape becomes longer in the axial direction, and the cantilever is stable Since it is difficult to realize a proper rotation, it is because β is optimally 30 or less in practical use.
<Other embodiments>
Next, a more effective embodiment of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view of a fan motor in which the impeller unit 1 and the motor unit 4 are integrally formed, which is cut along a plane passing through the rotation axis. In principle, it has the same configuration as that of FIG. 2, and portions having the same functions will be described with the same reference numerals in FIG. 4. 4 is the direction of the axis of rotation of the centrifugal fan motor. In the following description, the right side of FIG. 4 is referred to as “upper side”, and the left side of FIG. 4 is referred to as “lower side”. This is not for limiting the actual mounting posture of the fan motor.

This fan motor includes an impeller unit 1 and a motor unit 4. The impeller unit 1 and the motor unit 4 are connected to each other side by side in the axial direction.
The impeller unit 1 is a cantilever type impeller used for a centrifugal fan motor, and includes a driving force transmission unit 11 to which a driving force from the motor unit 4 is input, and a lower end wall constituting unit 2 (rotating unit side) fixed thereto. , 12 (fixed portion side), and an impeller blade 3 composed of a plurality of blades arranged in the circumferential direction on the wall surface of the lower end wall constituting portion 2 and extending in the rotation axis direction. The impeller blade 3 is supported in a cantilever manner. Specifically, the lower end is fixed to the lower end wall constituting part 2, but the upper end is not supported by anything. When the impeller unit 1 rotates, the airflow in the axial direction flows from the opening 9 on the upper end side of the impeller blade 3 toward the upper surfaces of the lower wall components 2 and 12. The lower end wall constituting portion 2 is an annular portion and belongs to the rotating portion side, and the lower end wall constituting portion 12 is a disk portion provided on the inner periphery thereof and belongs to the fixed portion side. It has a disk shape as a whole. The impeller unit 1 further includes an annular connecting unit 10 that connects the impeller blades 3 at the upper end. In this embodiment, the driving force transmitting portion 11 is an extension extending from the lower end wall constituting portion 2 to the motor portion 4 side, and more specifically, an extended cylindrical portion covering the entire outer surface of the motor portion 4 in the axial direction. Make up. As described above, since the driving force transmitting portion 11 of the impeller portion 1 has a large area in close contact with the rotor holder 25 (the portion supported by the pair of bearings 23 and 24), the rotation stability of the impeller portion 1 is ensured. Is further improved, and as a result, loss due to vibration is reduced. That is, the efficiency of the fan motor is further increased. In addition, the impeller blades 3, the lower end wall constituting parts 2, 12, and the driving force transmitting part 11 are integrally formed, and constitute the impeller part 1 having a single structure.

  The motor section 4 has a so-called outer rotor structure in which the rotor section is on the outer peripheral side. The rotor section of the motor section 4 includes a rotor holder 25 and a rotor magnet 26. The rotor magnet 26 is closely fixed to the inner peripheral surface of the rotor holder 25. The rotor holder 25 is made of a magnetic material, constitutes a part of a magnetic circuit as a yoke, and further functions as a reinforcing material in a connection portion with the driving force transmission unit 11. The rotor holder 25 is longer than the rotor magnet 26 in the rotation axis direction, and both ends in the axial direction extend in the axial direction from both ends in the axial direction of the rotor magnet 26. On the other hand, the fixed part of the motor part 4 is constituted by a shaft 20, a bracket 21, and a stator 22. The lower end of the shaft 20 is fixed to the bracket 21, and the whole extends on the inner peripheral side of the rotor holder 25 and the rotor magnet 26. The stator 22 is fixed to the shaft 20, faces the rotor magnet 26 with a gap in the radial direction, and forms a magnetic circuit together. A current supply line 27 is connected to the coil of the stator 22 from outside the motor unit 4. A pair of bearings (ball bearings) 23 and 24 arranged in the axial direction are provided as a bearing structure that rotatably supports the rotor unit of the motor unit 4 with respect to the fixed unit. The bearing 23 is a member that supports the lower end of the rotor portion. The outer ring 31 is fixed to the inner peripheral surface of the lower end of the rotor holder 25, and the inner ring 32 is fixed to the central projection of the bracket 21. The upper surface of the outer ring 31 is in contact with the lower surface of the rotor magnet 26. The bearing 24 is a member that supports the upper end of the rotor unit. The outer ring 31 is fixed to the inner peripheral surface of the upper end of the rotor holder 25, and the inner ring 32 is fixed to the upper end of the shaft 20. The lower surface of the outer race 31 is in contact with the upper end surface of the rotor magnet 26. Since the pair of bearings 23 and 24 are arranged so as to sandwich the stator 22 from above and below, a span between the bearings can be ensured, and stable support of the rotating portion including the cantilever impeller becomes possible. ing. Specifically, it is possible to make the distance between the two bearings 23 and 24 equal to or close to the axial length of the motor; m, to ensure the maximum bearing span and to make the impeller section 1 Rotational run-out of the rotating parts including it is minimized. Further, since the outer races 31 of the bearings 23 and 24 are fixed to the rotor holder 25 and the inner race 32 is fixed to the shaft portion (specifically, the protruding portion of the bracket 21 and the shaft 20), the support of the rotating portion is stabilized.

Next, a connection structure between the motor unit 4 and the impeller unit 1 will be described. The driving force transmission unit 11 of the impeller unit 1 is fixed so as to cover the entire outer peripheral surface of the rotor holder 25 of the motor unit 4. The upper end surface of the rotor holder 25 and the upper surface of the outer ring 31 of the bearing 24 are in contact with the lower surface of the lower end wall component 2. As described above, since the motor side wall surface of the lower end wall constituting portion 2 of the impeller portion 1 and / or a portion connected thereto is directly fixed to the bearing 24, the fan motor is shortened in the axial direction. The motor side wall surface of the lower end wall constituting portion 2 of the impeller portion 1 and / or a portion connected thereto may be fixed to the bearing 24 via a bearing holder.
Further, as described above, the lower end wall constituting portions 2 and 12 of the impeller portion 1 have not only a function of blocking the airflow in the axial direction in the impeller portion 1 but also a function as a wall surface of the motor portion 4. ing. In other words, the motor part 4 and the impeller part 1 are integrally formed with the lower end wall constituting parts 2 and 12 as common parts. Therefore, the number of parts is reduced, and the size of the fan motor is reduced in the axial direction. Furthermore, the weight of the fan motor is reduced.

  The present invention aims at effectively cooling a portable thin electronic device, has a long impeller in a rotation axis direction, and is cantilevered so as to be stably rotatable even at a rotation speed of 5000 rpm or more. An impeller 1 having a structure is employed. In the impeller section 1 of the present invention, for example, when the size of r = 6.5 mm and h = 23 mm, the impeller blade 3 uses a resin molded product having a thickness of 0.2 mm and holds both ends of the impeller with bearings. Then, sufficient strength cannot be secured. In addition, the area of the opening 9 serving as the airflow inlet cannot be sufficiently secured, and sufficient static pressure and cooling efficiency cannot be realized. In addition, in order to realize the cooling performance with high static pressure and high efficiency, which is a feature of the present invention, at least a rotation speed of 5000 rpm or more is necessary to make the maximum flow velocity point appear. Because 2r> h, it is necessary to generate a sufficient exhaust flow B (see FIG. 2). In order to minimize the loss due to the intake air flow A hitting the upper surfaces of the lower end wall components 2 and 12, it is more desirable that the motor rotation speed be 10,000 rpm or more in order to effectively switch to the exhaust air flow B. It becomes.

As a result, a small fan motor with high static pressure, high efficiency, and unprecedented performance was realized. More practically, in the fan motor of the present invention having an impeller of, for example, r = 5 mm and h = 10 mm, by rotating at 30,000 rpm, an unprecedented high efficiency fan motor could be realized. . The range of the number of rotations n in the present application is desirably more than 5000 rpm, and more desirably more than 10,000 rpm.
The fan motor according to the present invention has been developed for cooling portable electronic devices and small devices.In order to obtain higher cooling efficiency, the fan motor is used at a higher rotation speed because of the smaller fan shape. It is desirable to do. Usually, it is recommended to use in the range of 20,000 rpm to 30,000 rpm, but it is necessary to satisfy requirements such as motor performance, balance between power consumption and cooling performance, realization of vibration loss and noise amount below a certain level, and the like. Because. If a high-performance motor that satisfies these conditions can be realized sufficiently, a fan motor with higher static pressure and higher cooling efficiency can be realized by operating the motor at a rotational speed of 30,000 rpm or more, and more than 40,000 rpm.

  On the other hand, the diameter 2r of the impeller blade in this case is practically desirably 25 mm or less. This is because the thickness of a portable electronic device is usually about 25 mm, and it is necessary to incorporate the electronic device in the portable electronic device. When a mobile phone or the like is considered, the diameter is preferably 12.5 mm or less. Of course, the characteristics of the fan motor of the present invention can be realized even with a larger impeller blade having a diameter of 30 mm or 40 mm. However, the loss due to the collision of the intake air flow A with the lower end wall components 2 and 12 can be reduced. In order to suppress this, a high-speed rotation of 5000 rpm or more, desirably 10,000 rpm or more is required, and as the diameter of the fan increases, the load on the motor increases. Although it can be realized by using a high-performance motor, it is practically desirable to employ an impeller blade of 2r ≦ 12.5 mm with a smaller motor load. Further, it is more preferable that 2r ≦ 5 mm. Assuming that the entire axial length of the motor section 4 and the impeller section 1 (the axial distance from the lower end of the bearing 23 to the upper end of the impeller blade 3) is k, it is preferable that k <100 mm. Further, it is desirable that k <70 mm. This is because it is necessary to incorporate the fan impeller into a portable electronic device.

Part or all of the impeller unit 1 is made of a liquid crystal polymer, a carbon fiber reinforced liquid crystal polymer, a glass fiber reinforced liquid crystal polymer, a carbon fiber and a glass fiber reinforced liquid crystal polymer, soft iron, stainless steel, aluminum, or ceramic. Is preferred. As a result, the impeller unit 1 can realize a reduction in weight and size while securing sufficient rigidity.
As described above, the present invention desirably realizes a fan motor with high static pressure and high efficiency by rotating a cantilever impeller having a diameter 2r of 25 mm or less at a high speed of 5000 rpm or more. As a result of detailed simulations and actual tests, it has become clear that the following two conditions must be considered as prerequisites. FIG. 5 is a graph showing the results. Note that, since the main purpose of this graph is to show a tendency, the energy value on the vertical axis is subjected to predetermined normalization with respect to the vibration component, the windage component, and the product thereof, so that the energy value is easy to see.
The first condition is that h is large enough to minimize windage damage, so that m <h. The reason for the windage loss is, as described above, a loss due to the intake air flow A colliding with the upper surfaces of the lower end wall components 2 and 12, a loss due to an increase in the size of the turbulent vortex, and other losses. This is because it is considered that when m <h, those causes can be eliminated.

The second condition is that h is not unnecessarily large in order to minimize the rotational runout and other vibrations of the impeller, and as a result, h / 2 <m. This is because the run-out of the cantilever impeller is likely to occur unless the span m of the motor bearing is sufficiently long relative to the length h of the cantilever.
FIG. 5 shows the results of measuring the energy lost due to vibration loss and the energy lost due to windage loss by changing the ratio of h to m (h / m). The impeller used in the experiment has r = 6.5 mm, h = 23 mm, and the rotation speed n is 30,000 rpm.
As h / m decreases, the energy lost due to windage increases. Thus, in the range of h / m> 0.5, desirably h / m> 1.0, and more desirably h / m> 1.5 (that is, when the first condition is satisfied), the windage loss It can be understood that the energy lost due to is sufficiently reduced. Conversely, as h / m increases, the energy lost due to vibration loss increases. Thus, the vibration loss in the range of h / m <5.0, preferably h / m <4.0, and more preferably h / m <3.0 (that is, when the second condition is satisfied). It can be understood that the energy lost due to is sufficiently reduced. Even if only one of the first and second conditions described above is satisfied, it is possible to obtain a sufficiently low energy loss state by changing the shape of the member and other parameters. Can be.

Furthermore, in order to comprehensively evaluate the energy lost due to the vibration loss and the energy lost due to the windage loss, when the product of the two is calculated, the energy lost when h / m is in the range of 0.5 to 5.0 is obtained. It was found that the energy was sufficiently small, the energy lost in the range of 1.0 to 4.0 was even smaller, and the energy lost in the range of 1.5 to 3.0 was the smallest.
In the above description, the outer rotor type motor of the fixed shaft type has been described. However, it is apparent that the same configuration is possible with the inner rotor type motor (not shown) of the shaft rotating type. In this case, the driving force transmitting portion 11 which is an extended cylindrical portion of the impeller portion is replaced with a connecting portion with a shaft, and the lower end wall constituting portion 2 is fixed to the inner ring 32 instead of the outer ring 31 of the bearing. (Neither is shown).
Next, another embodiment of the present invention will be described with reference to FIG. FIG. 6 is a cross-sectional view of a fan motor in which an impeller unit and a motor unit are integrally formed, taken along a plane passing through the rotation axis, as in FIG. 4. The difference between the fan motor of this embodiment and the fan motor of the above embodiment is that the bearing of the motor unit uses a slide bearing or a fluid dynamic pressure bearing instead of a ball bearing.

This fan motor includes an impeller unit 51 and a motor unit 54. The impeller unit 51 and the motor unit 54 are connected to each other side by side in the axial direction.
The impeller unit 51 is a cantilever type impeller used for a centrifugal fan motor, and includes a driving force transmitting unit 61 to which a driving force from the motor unit 54 is input, and a lower wall forming unit fixed to an upper inner periphery in the axial direction. 52, a protruding portion 62, and an impeller blade 53 composed of a plurality of blades arranged in the circumferential direction on the upper end surface of the lower end wall constituting portion 52 and extending in the rotation axis direction. The impeller blades 53 are cantilevered, and the lower end is supported by the lower wall portion 52, but the upper end is not supported by anything. When the impeller part 51 rotates, the airflow in the axial direction flows from the opening part 59 on the upper end side of the impeller blade 53 toward the lower wall part 52 and the wall surface of the protruding part 62. The lower end wall constituting portion 52 is an annular portion where the impeller blades 53 and the driving force transmitting portion 61 extend from the outer peripheral edge, and the projecting portion 62 is a disk portion provided on the inner periphery and projecting upward in the axial direction. Yes, the shaft 78 is fixedly held. The impeller section 51 further includes an annular connecting section 60 that connects the impeller blades 53 at the upper end. In this embodiment, the driving force transmitting portion 61 is an extended portion extending from the lower end wall forming portion 52 to the outer peripheral side of the motor portion 54, and more specifically, an extended cylinder that covers the entire outer surface of the motor portion 54 in the axial direction. Department. As described above, since the area where the driving force transmitting portion 61 is in close contact with the rotating portion of the motor portion 54 is increased, the stability of the impeller portion 51 during rotation is further improved, and as a result, loss due to vibration is reduced. I do. That is, the efficiency of the fan motor is further increased. In addition, the impeller blade 53, the lower end wall forming portion 52, the projecting portion 62, and the driving force transmitting portion 61 are integrally formed to form the impeller portion 51 having a single structure.

  The motor section 54 has a so-called outer rotor structure in which the rotor section is on the outer peripheral side. The rotor part of the motor part 54 includes a rotor holder 75, a rotor magnet 76, and a shaft 78. The rotor magnet 76 is fixed to the inner peripheral surface of the rotor holder 75. The rotor holder 75 is made of a magnetic material and forms a part of a magnetic circuit as a yoke. The rotor holder 75 has substantially the same length as the rotor magnet 76 in the rotation axis direction, and both ends in the axial direction substantially coincide with each other. One end of the shaft 78 is fixed to the center of the protrusion 62 of the impeller 51, and extends on the inner peripheral side of the rotor holder 75 and the rotor magnet 76. On the other hand, the fixed part of the motor part 54 is constituted by a bearing sleeve 74, a bracket 71 and a stator 72. The lower end of the bearing sleeve 74 is fixed to the bracket 71, and the whole extends on the inner peripheral side of the rotor holder 75 and the rotor magnet 76. A shaft 78 is arranged inside the bearing sleeve 74. A minute gap in the radial direction is formed between the outer peripheral surface of the shaft 78 and the inner peripheral surface of the bearing sleeve 74. The minute gap is filled with oil or gas to form a sliding bearing 73. The fluid dynamic pressure bearing may be configured by forming grooves for generating dynamic pressure on one or both surfaces. Note that the lower end surface of the shaft 78 may be supported on the center surface of the bracket 71 in a point contact state. In order to firmly connect and fix one end of the shaft 78 to the rotating part, the protruding part 62 may be formed of a strong material such as a metal. It may have a structure that is connected and fixed to the unit.

  The stator 72 is fixed to the outer peripheral surface of the bearing sleeve 74, faces the rotor magnet 76 with a gap in the radial direction, and forms a magnetic circuit together. Since the magnetic center position of the stator 72 in the axial direction is located axially below the magnetic center position of the rotor magnet 76 in the axial direction, the rotor magnet 76 is always magnetically biased downward in the axial direction. ing. The magnetic bias of the rotor magnet 76 in the axial direction in this manner balances the thrust load supporting force generated between the central surface of the bracket 71 and the distal end surface of the shaft 78. Therefore, the rotating part of the motor part 54 and the impeller part 51 are prevented from rising in the axial direction from the fixed part of the motor part 54. Such a magnetic bias may be obtained by displacing the magnetic center of the stator and the rotor magnet in the axial direction as described above, or by arranging a magnetic member at a position facing the rotor magnet in the axial direction in the bracket or by using a bracket. And magnets magnetized to the same or different polarities are respectively arranged on the portions of the rotating portion that are opposed to each other in the axial direction.Furthermore, a dedicated magnet and a magnetic member are provided on the bracket and the portion of the rotating portion that are opposed to each other in the axial direction. It can be realized by arranging.

The connection structure between the motor unit 54 and the impeller unit 51 will be described. The driving force transmitting section 61 of the impeller section 51 is fixed so as to cover the entire outer peripheral surface of the rotor holder 75 of the motor section 54. The upper end surface of the rotor holder 75 and the upper end surface of the rotor magnet 76 are in contact with the lower surface of the lower end wall component 52.
As described above, the lower end wall constituting portion 52 and the protruding portion 62 of the impeller portion 51 have not only a function of blocking the airflow in the axial direction in the impeller portion 51 but also a function as a wall surface of the motor portion 54. In other words, the motor part 54 and the impeller part 51 are integrally formed with the lower end wall constituting part 52 and the protruding part 62 as common parts. Therefore, the number of parts is reduced, and the size of the fan motor is reduced in the axial direction. Furthermore, the weight of the fan motor is reduced.
In this embodiment, the same functions and effects as those of the embodiment of FIG. 4 can be obtained. In addition, in this fan motor, since a sliding bearing or a fluid dynamic pressure bearing is used as a bearing of the motor section, further high-speed rotation and quietness (reduction of vibration and noise) of the impeller section are realized.

FIG. 7 shows a PQ characteristic diagram comparing the performance of the fan motor according to the present invention with the conventional sirocco fan and axial flow fan. This PQ characteristic diagram is a comparison diagram obtained at respective motor rotation speeds at which the noise amount of each fan motor becomes substantially equal. The fan motor according to the present invention has an impeller with a diameter of 10 mm and an axial length of 22 mm, while the sirocco fan has an impeller with a side of 15 mm and an axial length of 10 mm. The axial fan is a comparison target in which three fan motors each having an impeller having a side of 10 mm and an axial length of 7 mm are arranged adjacent to each other in the radial direction. All have the same bearing structure (for example, all ball bearings), and all have substantially the same impeller occupation volume.
It can be seen from FIG. 7 that the fan according to the present invention has significantly higher static pressure characteristics than the conventional fan. A fan motor having a certain PQ characteristic curve operates as an operating point at the intersection of the PQ curve and a system impedance curve corresponding to the air resistance, degree of sealing, etc. of the object to be cooled by the fan. . FIG. 7 shows the most typical system impedance curve, and the object to be cooled having a system impedance value above this curve is considered to be dense. The fan motor according to the present invention is intended to efficiently cool a small electronic device, and is intended for a very high-density object to be cooled. In such a high-density object to be cooled, the slope of the impedance curve becomes steeper. As can be seen from FIG. 7, the fan with high static pressure operates at the operating point at a higher position, and the cooling efficiency becomes higher. Will be higher. In this regard, the fan motor of the present invention realizes an unprecedented high static pressure fan, and can efficiently cool high-density electronic devices.

As described above, conventionally, a centrifugal fan that minimizes the space in the axial direction by using a flat impeller with a reduced length in the axial direction has been used. However, in the present invention, by reversing this conventional idea, by developing a high-efficiency centrifugal fan having a pencil type impeller shape that is long in the axial direction, for example, the electronic circuit of a portable personal computer called a mobile phone or a mobile PC is developed. The most suitable cooling fan was realized. The feature of the pencil-type centrifugal fan according to the present invention is that only by providing a small circular intake port, an air flow can be generated with maximum efficiency in an internal electronic circuit, and hot air can be exhausted from dispersed exhaust ports. is there. As a result, conventionally, heat generated during the operation of the electronic circuit cannot be sufficiently discharged to the outside, so that it is possible to provide a space-saving and sufficient cooling function for electronic devices that could not be compactly integrated. In addition, further miniaturization of electronic circuits has become possible.
Various changes can be made without departing from the spirit of the present invention, and the present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, the impeller unit and the motor unit constituting the fan motor are arranged side by side in the axial direction, but the motor unit is arranged on the inner peripheral side of the impeller unit as in the prior art shown in FIG. (That is, both may completely overlap in the axial direction or may partially overlap.)

  Further, a part or the whole of the inner peripheral corner at the upper end side in the rotation axis direction of the impeller blade may be chamfered in an arc shape or a curved shape approximating this. By forming an arc-shaped chamfer on the inner peripheral corner of the upper end side of the impeller blades in the rotation axis direction, the intake air flow to the impeller flows more smoothly, and at the same time, unnecessary turbulence is suppressed. As a result, a fan impeller with good cooling efficiency and a fan motor using the same can be realized.

FIG. 1 is a plan view of a centrifugal fan motor according to an embodiment of the present invention. FIG. 1 is a longitudinal sectional view taken along the line XOYZ of FIG. 1. FIG. 2 is a perspective view of an impeller section of the centrifugal fan of FIG. FIG. 7 is a longitudinal sectional view of a fan motor as another embodiment of the present invention. FIG. 4 is a diagram showing the relationship between windage loss and vibration loss. FIG. 13 is a longitudinal sectional view of a fan motor as still another embodiment of the present invention. PQ comparison diagram of the fan motor of the present invention and another fan motor Top view of conventional centrifugal fan motor FIG. 7 is a longitudinal sectional view taken along line X ₁ -O ₁ -Y ₁ -Z _{1 in} FIG.

Explanation of reference numerals

1 Impeller part (fan impeller)
2 Lower end wall constituent part 3 Impeller blade 4 Motor part 5 Rotational force transmitting part 6 Housing 9 Impeller opening

Claims (28)

A cantilever impeller used for a centrifugal fan motor for cooling a portable electronic device or a small device, a rotating force transmitting unit to which a driving force from a motor unit is input, and a rotating force transmitting unit. An impeller comprising a lower end wall constituting part corresponding to a wall surface perpendicular to the direction of the rotation axis fixed and a plurality of blades arranged in a circumferential direction on the wall surface of the lower end wall constituting part and extending in the direction of the rotation axis. When the rotor rotates, an axial airflow flows toward the wall surface from an opening on the upper end side of the impeller blade. The outer peripheral diameter of the impeller blade is 2r, and the length in the rotation axis direction is Is h
2r ≦ h
And r ≦ 12.5 mm
A fan impeller, characterized in that: A cantilever impeller used for a centrifugal fan motor for cooling a portable electronic device or a small device, a rotating force transmitting unit to which a driving force from a motor unit is input, and a rotating force transmitting unit. An impeller comprising a lower end wall constituting part corresponding to a wall surface perpendicular to the direction of the rotation axis fixed and a plurality of blades arranged in a circumferential direction on the wall surface of the lower end wall constituting part and extending in the direction of the rotation axis. When the rotor rotates, an axial airflow flows toward the wall surface from an opening on the upper end side of the impeller blade. The outer peripheral diameter of the impeller blade is 2r, and the length in the rotation axis direction is Is h, 2πrh = απr2 for the parameter α
4 ≦ α ≦ 40
And r ≦ 12.5 mm
A fan impeller, characterized in that: A cantilever impeller used for a centrifugal fan motor for cooling a portable electronic device or a small device, a rotating force transmitting unit to which a driving force from a motor unit is input, and a rotating force transmitting unit. An impeller comprising a lower end wall constituting part corresponding to a wall surface perpendicular to the direction of the rotation axis fixed and a plurality of blades arranged in a circumferential direction on the wall surface of the lower end wall constituting part and extending in the direction of the rotation axis. When the rotor rotates, an axial airflow flows toward the wall surface from an opening on the upper end side of the impeller blade. The outer peripheral diameter of the impeller blade is 2r, and the length in the rotation axis direction is Is h, 2πrh = απr2 for the parameter α
5 ≦ α ≦ 35
And r ≦ 12.5 mm
A fan impeller, characterized in that: A cantilever impeller used for a centrifugal fan motor for cooling a portable electronic device or a small device, a rotating force transmitting unit to which a driving force from a motor unit is input, and a rotating force transmitting unit. An impeller comprising a lower end wall constituting part corresponding to a wall surface perpendicular to the direction of the rotation axis fixed and a plurality of blades arranged in a circumferential direction on the wall surface of the lower end wall constituting part and extending in the direction of the rotation axis. When the rotor rotates, an axial airflow flows toward the wall surface from an opening on the upper end side of the impeller blade. The outer peripheral diameter of the impeller blade is 2r, and the length in the rotation axis direction is Where h is the number of blades of the impeller blade, and d is the thickness of the blade, 2πrεh = βπr2 for the parameter β.
3 ≦ β ≦ 30
Where ε = (2πr−Zd) / 2πr
And 2r ≦ h
r ≦ 12.5mm
A fan impeller, characterized in that: In the fan impeller according to claim 1,
r <5mm
A fan impeller, characterized in that: A fan motor comprising: the fan impeller according to claim 1; and a motor unit having a rotating unit connected to the rotational force transmitting unit of the fan impeller. The fan motor according to claim 6, wherein k is a total axial length of the motor unit and the fan impeller.
k <100mm
A fan motor characterized in that: The fan motor according to claim 6, wherein k is a total axial length of the motor unit and the fan impeller.
k <70mm
A fan motor characterized in that: The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
It has a pair of bearings disposed in the direction of the rotation axis that rotatably holds the rotating part and the fixed part, and the length between both ends in the axial direction of the bearing is m,
1.5 <h / m <3.0
A fan motor characterized in that: The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
It has a pair of bearings disposed in the direction of the rotation axis that rotatably holds the rotating part and the fixed part, and the length between both ends in the axial direction of the bearing is m,
1.0 <h / m <4.0
A fan motor characterized in that: The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
It has a pair of bearings disposed in the direction of the rotation axis that rotatably holds the rotating part and the fixed part, and the length between both ends in the axial direction of the bearing is m,
0.5 <h / m <5.0
A fan motor characterized in that: The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
It has a pair of bearings arranged in the axial direction that rotatably holds the rotating part and the fixed part,
The fixed portion includes a stator,
The fan motor according to claim 1, wherein the pair of bearing portions are disposed at positions sandwiching the stator in a rotation axis direction. The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
A bearing portion for rotatably holding the rotating portion and the fixed portion,
A fan motor, wherein a side wall surface of a motor portion of the lower end wall constituting portion of the fan impeller and / or a portion connected thereto is fixed to the bearing portion directly or via a bearing holder. The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
A bearing portion for rotatably holding the rotating portion and the fixed portion,
The fan motor, wherein the lower end wall constituting portion of the fan impeller simultaneously constitutes a part of an upper wall surface of the motor portion. The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
It has a pair of bearings arranged in the direction of the rotation axis that rotatably holds the rotating part and the fixed part,
The fixing portion includes a shaft, and the inner rings of the pair of bearing portions are fixed to the shaft,
A fan motor, wherein the rotating portion includes a rotor holder, and the outer rings of the pair of bearing portions are fixed to the rotor holder. The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
A bearing portion arranged in a rotation axis direction for rotatably holding the rotating portion and the fixed portion,
The fan motor, wherein the rotating portion includes a rotor holder, and the rotating force transmitting portion is fixed so as to cover an outer peripheral surface of the rotor holder. The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
A bearing portion arranged in a rotation axis direction for rotatably holding the rotating portion and the fixed portion,
A fan motor, wherein the rotational force transmitting portion covers a peripheral outer peripheral surface of the rotating portion. The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
A bearing portion arranged in a rotation axis direction for rotatably holding the rotating portion and the fixed portion,
The rotating portion includes a magnetic rotor holder, a rotor magnet is fixedly attached to the inner peripheral surface of the rotor holder,
A fan motor, wherein the rotational force transmitting portion covers a peripheral outer peripheral surface of the rotating portion. The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
A sliding bearing portion or a fluid dynamic pressure bearing portion that rotatably holds the rotating portion and the fixed portion,
When the length between both ends in the axial direction of the bearing portion is m,
1.5 <h / m <3.0
A fan motor characterized in that: The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
A sliding bearing portion or a fluid dynamic pressure bearing portion that rotatably holds the rotating portion and the fixed portion,
When the length between both ends in the axial direction of the bearing portion is m,
1.0 <h / m <4.0
A fan motor characterized in that: The fan motor according to claim 6, wherein:
The motor unit includes a rotating unit and a fixed unit,
A sliding bearing portion or a fluid dynamic pressure bearing portion that rotatably holds the rotating portion and the fixed portion,
When the length between both ends in the axial direction of the bearing portion is m,
0.5 <h / m <5.0
A fan motor characterized in that: It is a fan motor according to claim 6 to 8 or claim 19 to 21,
The motor unit includes a rotating unit and a fixed unit,
A sliding bearing portion or a fluid dynamic pressure bearing portion that rotatably holds the rotating portion and the fixed portion,
The fixing unit includes a stator,
A fan motor, wherein the sliding bearing portion or the fluid dynamic pressure bearing portion has both ends in the axial direction located outside the both ends in the axial direction of the stator in the rotation axis direction. It is a fan motor according to claim 6 to 8 or claim 19 to 21,
The motor unit includes a rotating unit and a fixed unit,
A bearing portion arranged in a rotation axis direction for rotatably holding the rotating portion and the fixed portion,
The fixing part includes a bracket and a stator,
The rotating portion is integrally formed with the shaft so as to also serve as the lower end wall forming portion of the impeller, and is integrally formed with a shaft holding portion to which one end of the shaft is fixed, and an outer diameter end portion of the shaft holding portion. A rotor holder fixed or fixed by adhesive or pressure welding or welding, and a rotor magnet fixedly held on the inner peripheral side of the rotor holder,
A fan motor having a structure in which an inner peripheral side of the rotor magnet is radially opposed to an outer peripheral side of the stator via a minute gap. A fan impeller according to any one of claims 1 to 5, or a fan impeller used in the fan motor according to claims 6 to 23, wherein a part or the entirety of an inner peripheral corner at an upper end side in a rotation axis direction of the impeller blades. A fan impeller characterized by being chamfered in an arc shape or a curve shape approximating the arc shape. A fan impeller according to claim 1 or claim 24 or a fan impeller used for a fan motor according to claim 6 to 23, wherein the fan impeller is a liquid crystal polymer, a carbon fiber reinforced liquid crystal polymer, or a glass fiber reinforced. A fan impeller comprising a liquid crystal polymer, a carbon fiber and glass fiber reinforced liquid crystal polymer, soft iron, stainless steel, aluminum or ceramic, a part or all of which is formed. A fan motor having the fan impeller according to claim 1 or claim 24 or a fan motor according to claim 6 to 23, wherein the fan impeller is a liquid crystal polymer, a carbon fiber reinforced liquid crystal polymer, or a glass fiber reinforced liquid crystal. A fan motor characterized in that a part or the whole thereof is constituted by a polymer, a liquid crystal polymer reinforced with carbon fiber and glass fiber, soft iron, stainless steel, aluminum or ceramic. The fan motor according to claim 6, wherein the rotation speed of the motor is n,
n ≧ 5000 rpm
A fan motor characterized in that: The fan motor according to claim 6, wherein the rotation speed of the motor is n,
n ≧ 10000 rpm
A fan motor characterized in that:

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