FAN MOTOR

1. FIELD OF THE INVENTION

The present disclosure relates to a fan motor.

2. BACKGROUND

Conventionally, an axial flow fan motor that rotates an impeller using a driving force of a motor and generates an air flow in the axial direction is known. The axial flow fan motor is mounted on, for example, a home appliance, an OA device, a transport device, or the like, and is used for the purpose of cooling an electronic component or circulating the gas in the device housing. Moreover, a fan motor may be used for circulation of the gas in the server room where many electronic devices are installed.

In order to increase the air volume of the fan motor, it is devised to increase the size of the impeller. However, the fan motor is upsized. If the size of the impeller is increased without increasing the size of the fan motor, the thickness of the fan motor housing becomes thinner. As a result, the rigidity of the housing is reduced, which may cause unpleasant vibration and noise. In addition, the natural frequency decreases due to the decrease in the rigidity of the housing. As a result, resonance with the magnetic excitation occurs when the fan motor is driven, which may cause unpleasant vibration or noise. FIG. 18 is a perspective view showing a result of analyzing a horizontal vibration mode in a housing 5X used for a conventional fan motor. FIG. 19 is a perspective view showing a result of analyzing an axial vibration mode in a housing 5Y used in a conventional fan motor. The housing 5X is formed as a single member by resin injection molding or the like, and the housing 5Y is formed of upper and lower two members.

For example, in the axial flow fan disclosed in JP 2016-125394 A, rectangular recessed portions are formed on each of two opposite side surfaces of the fan frame. Thereby, when the dimension and the position of the recessed portions satisfy specific conditions, the displacement amount of the fan frame when resonance occurs at the time of driving can be restrained small.

However, in the structure of JP 2016-125394 A, when the recessed portion is formed, the thickness of the resin at the corner portion of the fan frame becomes large, and depressions, that is, so-called sink marks, may be generated on the surface during resin molding.

SUMMARY

Example embodiments of the present disclosure provide fan motors each capable of increasing rigidity of a housing and reducing or preventing unpleasant vibration and noise at a time of driving while reducing or preventing generation of sink marks.

An example embodiment of the present disclosure is directed to a fan motor including a motor, an impeller, and a housing. The motor includes a stationary portion including a stator, and a rotating portion that rotates about a center axis extending vertically. The impeller includes a plurality of blades and rotates with the rotating portion. The housing accommodates at least a portion of the motor and the impeller in the housing. The housing includes a cylindrical portion, a flange portion, and one or more ribs. The cylindrical portion has a cylindrical shape, extends in an axial direction, and accommodates at least a portion of the motor and the impeller in the cylindrical portion. The flange portion protrudes radially outward from an upper end portion or a lower end portion of the cylindrical portion. The rib has a columnar shape and extends from the flange portion on an outer peripheral surface of the cylindrical portion. The ribs are inclined against the axial direction.

According to an example embodiment of the present disclosure, by providing one or more ribs each of which has a columnar shape and extends from the flange portion on the outer peripheral surface of the cylindrical portion, each of the ribs being inclined against the axial direction, it is possible to increase the rigidity of the housing and to reduce or prevent unpleasant vibration and noise at the time of driving. Moreover, since the thickness of the housing in portions other than the ribs is able to be reduced, generation of sink marks is able to be reduced or prevented.

The above and other elements, features, steps, characteristics and advantages of the present disclosure will become more apparent from the following detailed description of the example embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal cross-sectional view of a fan motor according to a first example embodiment of the present disclosure.

FIG. 2 is a partial longitudinal cross-sectional view of the fan motor according to the first example embodiment of the present disclosure.

FIG. 3 is a perspective view of a housing according to the first example embodiment of the present disclosure.

FIG. 4 is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 5 is a diagram showing a result of analyzing the relationship between the inclination of a rib and the natural frequency of the housing according to the first example embodiment of the present disclosure.

FIG. 6A is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 6B is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 6C is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 6D is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 7 is a diagram showing the result of analyzing the relationship between the thickness of the rib and the natural frequency of the housing according to the first example embodiment of the present disclosure.

FIG. 8A is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 8C is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 8E is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 8F is a side view of the housing according to the first example embodiment of the present disclosure.

FIG. 9 is a diagram showing a result of analyzing the relationship between the position of the rib and the natural frequency of the housing according to the first example embodiment of the present disclosure.

FIG. 10A is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 10G is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 10H is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 10I is a top view of a housing according to the first example embodiment of the present disclosure.

FIG. 10C is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 11 is a diagram showing a result of analyzing the relationship between the position of the rib and the natural frequency of the housing according to the first example embodiment of the present disclosure.

FIG. 12A is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 12J is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 12K is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 12L is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 12C is a top view of the housing according to the first example embodiment of the present disclosure.

FIG. 13 is a longitudinal cross-sectional view of a fan motor according to a second example embodiment of the present disclosure.

FIG. 14 is a perspective view of a housing according to the second example embodiment of the present disclosure.

FIG. 15 is a side view of the housing according to the second example embodiment of the present disclosure.

FIG. 16 is a diagram showing a result of analyzing the relationship between the position of a rib and the natural frequency of the housing according to the second example embodiment of the present disclosure.

FIG. 17A is a top view of the housing according to the second example embodiment of the present disclosure.

FIG. 17B is a top view of the housing according to the second example embodiment of the present disclosure.

FIG. 17C is a top view of the housing according to the second example embodiment of the present disclosure.

FIG. 17D is a top view of the housing according to the second example embodiment of the present disclosure.

FIG. 17E is a top view of the housing according to the second example embodiment of the present disclosure.

FIG. 17F is a top view of the housing according to the second example embodiment of the present disclosure.

FIG. 18 is a perspective view showing a result of analyzing a vibration mode in a housing of a conventional fan motor.

FIG. 19 is a perspective view showing a result of analyzing a vibration mode in the housing of the conventional fan motor.

DETAILED DESCRIPTION

Hereinafter, example embodiments of the present disclosure will be described with reference to the drawings. Note that in the present application, a direction parallel to the center axis of a motor, described below, is referred to as an “axial direction”, a direction orthogonal to the center axis of the motor is referred to as a “radial direction”, and a direction along the arc about the center axis of the motor is referred to as a “circumferential direction”. Furthermore, in the present application, the axial direction is a vertical direction, a side from which air is taken is referred to as an “air intake side” or simply an “upper side”, and a side from which air is discharged is referred to as an “exhaust side” or simply a “lower side”. However, the terms “upper side” and “lower side” are merely for the convenience of description, and have nothing to do with the direction of gravity. The fan motor according to the present disclosure may be used in any orientation.

In addition, a “parallel direction” in the present application includes a substantially parallel direction. In addition, an “orthogonal direction” in the present application includes a substantially orthogonal direction.

1. First Example Embodiment

1-1. Overall Configuration of Fan Motor

FIG. 1 is a longitudinal cross-sectional view of a fan motor 10 according to a first example embodiment.

The fan motor 10 is used, for example, as a device for supplying a cooling air flow to a home appliance such as a refrigerator, or to a room such as a server room in which a plurality of electronic devices are disposed. The fan motor 10 may be used alone, or a plurality of fan motors 10 may be combined and used simultaneously. For example, a plurality of fan motors 10 may be installed in one server room and driven simultaneously.

As shown in FIG. 1, the fan motor 10 has a motor 1, an impeller 4, and a housing 5. The fan motor 10 is an axial flow fan that generates an air flow downward along a center axis 9. When the fan motor 10 is driven, the air is taken in from the upper side of the fan motor 10 that is an air intake side, and the air is sent out toward the lower side of the fan motor 10 that is an exhaust side, through a wind tunnel 50 in the housing 5.

1-2. Configuration of Motor and Impeller

First, the configurations of the motor 1 and the impeller 4 will be described. FIG. 2 is a partial longitudinal cross-sectional view of the fan motor 10 according to the first example embodiment. The following description refers to FIG. 2, and FIG. 1 as appropriate.

The motor 1 has a stationary part 2 and a rotating part 3. The stationary part 2 is stationary relative to a device in which the fan motor 10 is disposed, and the like. The rotating part 3 is rotatably supported around the center axis 9 extending vertically, with respect to the stationary part 2.

As shown in FIG. 2, the stationary part 2 includes a stator 22, a circuit board 23, and a bearing holder 24. The stator 22 is fixed to an outer peripheral surface of the bearing holder 24. The stator 22 includes a stator core 221 and coils 222. The stator core 221 has a plurality of teeth. Each tooth extends in the radial direction. Each of the coils 222 is formed of a conducting wire wound around the teeth. An end portion of the conducting wire is connected to the circuit board 23.

The bearing holder 24 is a cylindrical member extending along the center axis 9. A lower portion of the bearing holder 24 is fixed to an inner peripheral surface of a base part 21 described later, with an adhesive, for example. A bearing part 25 is disposed on a radially inner side of the bearing holder 24. The bearing part 25 is, for example, a ball bearing. An outer ring of the bearing part 25 is fixed to the inner peripheral surface of the bearing holder 24. An inner ring of the bearing part 25 is fixed to a shaft 31 described later. Thereby, the shaft 31 is rotatably supported with respect to the stationary part 2. However, the motor 1 may have another type of bearing part such as a slide bearing or a fluid bearing, instead of the ball bearing.

The rotating part 3 has a shaft 31, a rotor holder 32, an annular member 33, and a magnet 34. The shaft 31 is a columnar member arranged to extend along the center axis 9. The shaft 31 is rotatably supported by the bearing part 25. An upper end portion of the shaft 31 protrudes upward from the bearing holder 24. When the motor 1 is driven, the shaft 31 rotates about the center axis 9.

The rotor holder 32 is a lidded cylindrical member having a rotor lid part 321 and a rotor cylinder part 322. The rotor lid part 321 spreads in a disk shape substantially perpendicularly to the center axis 9. The rotor cylinder part 322 extends in an axial direction from the rotor lid part 321 toward the exhaust side. A material of the rotor holder 32 is, for example, metal or resin. A central portion of the rotor lid part 321 is fixed to an upper end portion of the shaft 31 via an annular member 33. Thus, the rotor holder 32 rotates with the shaft 31. The rotor lid part 321 is disposed on the air intake side of the stationary part 2. The rotor cylinder part 322 is disposed on a radially outer side of the stator 22. The magnet 34 is fixed to the inner peripheral surface of the rotor cylinder part 322.

The motor 1 further has lead wires (not shown) electrically connected to the stator 22. One end of a lead wire (not shown) is connected to the circuit board 23. The other end is drawn radially outward from a cylindrical part 51 described later, and is connected to, for example, a power supply provided outside the fan motor 10.

When a driving current is supplied to the coils 222 of the stator 22 via the lead wires (not shown) and the circuit board 23, a magnetic flux is generated in the plurality of teeth. Then, by the action of the magnetic flux between the teeth and the magnet 34, a circumferential torque is generated between the stationary part 2 and the rotating part 3. As a result, the rotating part 3 rotates about the center axis 9 with respect to the stationary part 2. Thereby, the impeller 4 to be described later, which is fixed directly or indirectly to the rotating part 3, rotates around the center axis 9 together with the rotating part 3.

The impeller 4 has a cup part 41 and a plurality of blades 42. The cup part 41 covers the rotor lid part 321 and the rotor cylinder part 322 of the rotor holder 32. Each of the blades 42 extends radially outward from the outer peripheral surface of the cup part 41. The blades 42 are arranged at substantially equal intervals in the circumferential direction. The number of blades 42 is not particularly limited. The impeller 4 rotates with the rotating part 3.

1-3. Configuration of Housing

Next, the configuration of the housing 5 will be described. FIG. 3 is a perspective view of the housing 5 according to the first example embodiment. FIG. 4 is a side view of the housing 5 according to the first example embodiment.

The housing 5 is a casing that accommodates at least part of the motor 1 and the impeller 4 therein. As shown in FIGS. 3 and 4, the housing 5 has a base part 21, a cylindrical part 51, a flange part 52, one or more base connection parts 53, and one or more ribs 54. In addition, the housing 5 has a rectangular solid shape that opens upward and downward.

The base part 21 is a disk-shaped part that is disposed below the stator 22 of the motor 1, and extends radially outward from the periphery of the bearing holder 24. As described above, a lower portion of the bearing holder 24 is fixed to the inner peripheral surface of the base part 21 with, for example, an adhesive. The motor 1 is disposed on the base part 21. The motor 1 is supported by the base part 21.

The cylindrical part 51 is a cylindrical part extending in the axial direction from the air intake side (upper side) to the exhaust side (lower side) along the center axis 9. The cylindrical part 51 extends in a substantially cylindrical shape on the radially outer side of the impeller 4. The cylindrical part 51 accommodates at least part of the motor 1 and the impeller 4 therein.

The flange part 52 is a part that protrudes radially outward at four places in the circumferential direction of the cylindrical part 51. The flange part 52 has an upper flange part 521 and a lower flange part 522. The upper flange part 521 protrudes radially outward from an upper end portion of the cylindrical part 51. The lower flange part 522 protrudes radially outward from a lower end portion of the cylindrical part 51. The housing 5 has a rectangular shape when viewed from the upper side. The housing 5 has a rectangular shape when viewed from the lower side. That is, the housing 5 has a rectangular solid shape that opens upward and downward. In the present example embodiment, the axial thickness of the upper flange part 521 and the axial thickness of the lower flange part 522 are equal to each other. The rigidity of each part of the housing 5 is lowered as it goes away from the center axis 9 in the radially outward direction, and resonance tends to occur when the fan motor 10 is driven. For example, an end portion on the radially outer side of the upper flange part 521 is the least rigid in the housing 5. Also, an end portion on the radially outer side of the lower flange part 522 has low rigidity, similarly. However, since the base connection part 53 is provided below the housing 5 as described later, the end portion on the radially outer side of the lower flange part 522 has higher rigidity than the end portion on the radially outer side of the upper flange part 521. The upper flange part 521 or the lower flange part 522 is attached, for example, by screwing to a frame body such as a device in which the fan motor 10 is installed. The flange part 52 may be configured only of the upper flange part 521 or the lower flange part 522.

Each of the base connection parts 53 is a columnar part that extends radially outward from at least a portion of the outer peripheral surface of the base part 21 and is connected to at least a portion of the inner peripheral surface of the cylindrical part 51. Thereby, the position of the stationary part 2 of the motor 1 with respect to the housing 5 is fixed. Further, by providing the base connection part 53, the lower portion of the cylindrical part 51 and the lower flange part 522 have higher rigidity than the upper portion of the cylindrical part 51 and the upper flange part 521. One or more base connection parts 53 are provided at the lower portion of the housing 5. However, the number of base connection parts 53 is not limited.

On the outer peripheral surface of the cylindrical part 51, one or more columnar ribs 54 extending from the flange parts are further provided. The details of the rib 54 will be described later. In the present example embodiment, the base part 21, the cylindrical part 51, the flange part 52, the one or more base connection parts 53, and the one or more ribs 54 are formed as a single member by resin injection molding. However, these may be separate members.

1-4. Configuration of Rib

Next, the configuration of the rib 54 will be described.

As described above, each of one or more ribs 54 is located on the outer peripheral surface of the cylindrical part 51, and connects the upper flange part 521 and the lower flange part 522. As a result, the rigidity of the housing 5 is increased, and the natural frequency of the housing 5 to the horizontal vibration is increased. As a result, when the fan motor 10 is driven, the resonance amplitude at the time of resonance with the magnetic excitation can be reduced, and noise can be reduced.

It is desirable that each of the ribs 54 is inclined against the axial direction in a direction away from the center axis 9 from the bottom to the top of the housing 5. FIG. 5 is a diagram showing a result of analyzing the relationship between the inclination of the rib 54 and the natural frequency of the housing 5 to the horizontal vibration. The vertical axis represents an analysis result of the natural frequency of each housing 5, based on the analysis result of the natural frequency of the housing 5 of A. A represents a result of analyzing the natural frequency of the housing 5 to the horizontal vibration when the rib 54 is not provided to the housing 5. B represents a result of a similar analysis in the case where the rib 54 parallel to the axial direction is provided to the housing 5. C represents a result of a similar analysis in the case where the rib 54 that is inclined in a direction away from the center axis 9 from the bottom to the top of the housing 5 is provided. D represents a result of a similar analysis in the case where the rib 54 that is inclined in a direction away from the center axis 9 from the top to the bottom of the housing 5 is provided. FIGS. 6A, 6B, 6C, and 6D show side views of the housings 5 of A, B, C and D, respectively, for reference. Note that the housings 5 of B to D each have two ribs on each of the four side surfaces of the rectangular solid shape.

As shown in FIG. 5, when the analysis results of A to D are compared, C has the highest natural frequency of the housing 5 to the horizontal vibration. A portion on the radially inner side of the lower flange part 522 is higher in rigidity than a portion on the radially outer side of the upper flange part 521. In the case of C, a portion on the radially outer side of the upper flange part 521 is connected to a portion on the radially inner side of the lower flange part 522. Therefore, the rigidity of the housing 5 as a whole is increased, and the natural frequency is increased. As a result, when the fan motor 10 is driven, the resonance amplitude at the time of resonance with the magnetic excitation can be reduced, and noise can be reduced.

The thickness of the rib 54 is preferably equal to or less than the thickness in the axial direction of the upper flange part 521 or the lower flange part 522. Further, it is desirable that the thicknesses of the ribs 54 are substantially the same. FIG. 7 is a diagram showing a result of analyzing the relationship between the thickness of the rib 54 and the natural frequency of the housing 5 to the horizontal vibration. The vertical axis represents an analysis result of the natural frequency of each housing 5, based on the analysis result of the natural frequency of the housing 5 of A. In FIG. 7, A represents a result of analyzing the natural frequency of the housing 5 to the horizontal vibration when the rib 54 is not provided to the housing 5. C, E, and F represent results of similar analyses in the case where the rib 54 inclined in a direction away from the center axis 9 from the bottom to the top of the housing 5 is provided. In addition, the housings 5 of C, E, and F each have two ribs 54 on each of the four side surfaces in the rectangular solid shape. However, while the thickness of the rib 54 of C is equal to the thickness in the axial direction of the upper flange part 521 and the lower flange part 522, the thickness of the rib 54 of E is smaller than the thickness of the rib 54 of C. Further, the thickness of the rib 54 of F is further smaller than the thickness of the rib 54 of E. FIGS. 8A, 8C, 8E, and 8F show side views of the housings 5 of A, C, E, and F, respectively, for reference.

As shown in FIG. 7, when the analysis results of A, C, E, and F are compared, C has the highest natural frequency of the housing 5 to the horizontal vibration. The thickness of the rib 54 of C is equal to the thickness in the axial direction of the upper flange part 521 and the lower flange part 522, and has a sufficient size, so that the rigidity of the housing 5 as a whole is increased and the natural frequency is increased. On the other hand, in E and F, the thickness of the rib 54 is smaller than that of C, so that the rigidity of the housing 5 as a whole is lower than that of C, and the natural frequency is lower than that of C. When the thickness of the rib 54 is made larger than the thickness in the axial direction of the upper flange part 521 and the lower flange part 522, depressions, that is, so-called sink marks, may be generated on the surface during resin molding of the housing 5 having the rib 54. Therefore, it is desirable that the thickness of the rib 54 is not too large, and is substantially the same as the thickness in the axial direction of the upper flange part 521 and the lower flange part 522.

It is desirable that two or more ribs 54 are provided on each of the four side surfaces of the rectangular solid shape of the housing 5. FIG. 9 is a diagram showing a result of analyzing the relationship between the position of the rib 54 and the natural frequency of the housing 5 to the horizontal vibration. The vertical axis represents an analysis result of the natural frequency of each housing 5, based on the analysis result of the natural frequency of the housing 5 of A. In FIG. 9, A represents a result of analysis of the natural frequency of the housing 5 to the horizontal vibration when the rib 54 is not provided to the housing 5. G represents a result of a similar analysis in the case where two ribs 54 are provided to one of the four side surfaces of the rectangular solid shape of the housing 5. H represents a result of a similar analysis in the case where two ribs 54 are provided to one side surface of the four side surfaces of the rectangular solid shape of the housing 5, and to a side surface facing the one side surface. I represents a result of a similar analysis in the case where two ribs 54 are provided to one side surface of the four side surfaces of the rectangular solid shape of the housing, and to a side surface adjacent to the one side surface. C represents a result of a similar analysis in the case where two ribs 54 are provided to all of the four side surfaces of the rectangular solid shape of the housing 5. FIGS. 10A, 10G, 10H, 10I, and 10C show top views of the housings 5 of A, G, H, I, and C, respectively, for reference. The ribs 54 are provided at the positions of black circles in each top view.

As shown in FIG. 9, when the analysis results of A, G, H, I, and C are compared, C has the highest natural frequency of the housing 5 to the horizontal vibration. In the case of C, since two ribs 54 are provided to all of the four side surfaces of the rectangular solid shape of the housing 5, the rigidity of the housing 5 as a whole is increased and the natural frequency is increased. As a result, when the fan motor 10 is driven, the resonance amplitude at the time of resonance with the magnetic excitation can be reduced, and noise can be reduced.

In FIG. 9, when the analysis results of H and I are compared, I has a higher natural frequency of the housing 5 to the horizontal vibration. In H and I, two ribs 54 are provided to each of two side surfaces of the four side surfaces of the rectangular solid shape of the housing 5. However, in H, the two side surfaces face each other, whereas in I, the two side surfaces are adjacent to each other.

Hereinafter, as shown in FIGS. 10A, 10G, 10H, 10I, and 10C, a horizontal plane orthogonal to the axial direction is taken as an XY plane. Also, as shown in the top view of the housing 5, description will be given based on the premise that two of the four side surfaces of the rectangular solid shape of the housing 5 are parallel to the X axis, and the remaining two side surfaces are parallel to the Y axis. In the case of H, two ribs 54 are provided to each of two side surfaces parallel to the X-axis direction of the four side surfaces of the rectangular solid shape of the housing 5. Therefore, in H, the natural frequency of the housing 5 to the vibration in the X-axis direction in the horizontal direction (XY direction) is high. On the other hand, in the case of I, two ribs 54 are provided to one side surface parallel to the X-axis direction and to one side surface parallel to the Y-axis direction, of the four side surfaces in the rectangular solid shape of the housing 5. Therefore, in I, the natural frequency of the housing 5 to the vibration in the X-axis direction and the Y-axis direction in the horizontal direction (XY direction) is high. As a result, I has a higher natural frequency of the housing 5 to the horizontal vibration as a whole, than H. That is, in the case where two or more ribs 54 are provided to each of two side surfaces of the four side surfaces in a rectangular solid shape, when the ribs 54 are provided to two side surfaces adjacent to each other, the natural frequency of the housing 5 to the horizontal vibration can be further increased.

FIG. 11 is a diagram showing a result of analyzing the relationship between the position of the rib 54 and the natural frequency of the housing 5 to the horizontal vibration, as in FIG. 9. The vertical axis represents an analysis result of the natural frequency of each housing 5, based on the analysis result of the natural frequency of the housing 5 of A. In FIG. 11, A represents a result of analyzing the natural frequency of the housing 5 to the horizontal vibration when the rib 54 is not provided to the housing 5. J represents a result of a similar analysis in the case where one rib 54 is provided to one side surface and a side surface adjacent to the one side surface, of the four side surfaces of the rectangular solid shape of the housing 5. K represents a result of a similar analysis in the case where one rib 54 is provided to all of the four side surfaces of the rectangular solid shape of the housing 5. L represents a result of a similar analysis in the case where two ribs 54 are provided to one side surface parallel to the Y-axis of the four side surfaces of the rectangular solid shape of the housing 5, and one rib 54 is provided to each of two side surfaces adjacent to the one side surface. C represents a result of a similar analysis in the case where two ribs 54 are provided to all of the four side surfaces of the rectangular solid shape of the housing 5. FIGS. 12A, 12J, 12K, 12L, and 12C show top views of the housings 5 of A, J, K, L, and C, respectively, for reference. The ribs 54 are provided at the positions of black circles in each top view.

Similar to the analysis result of FIG. 9, as shown in FIG. 11, when the analysis results of A, J, K, L and C are compared, C has the highest natural frequency of the housing 5 to the horizontal vibration. In the case of C, since two ribs 54 are provided to all of the four side surfaces of the rectangular solid shape of the housing 5, the rigidity of the housing 5 as a whole is increased and the natural frequency is increased. As a result, when the fan motor 10 is driven, the resonance amplitude at the time of resonance with the magnetic excitation can be reduced, and noise can be reduced.

When the analysis results of K and L in FIG. 11 are compared with those of H and I in FIG. 9, the analysis results of K and L are at the same level as that of I, and the natural frequency of the housing 5 to the horizontal vibration is higher than that of H. In each of H, I, K, and L, four ribs 54 in total are provided to the four side surfaces of the rectangular solid shape of the housing 5. However, as shown in the top view of the housing 5, with the horizontal plane orthogonal to the axial direction also being the XY plane, in K and L, two ribs 54 in total are provided to each of a side surface parallel to the X-axis direction and a side surface parallel to the Y-axis direction, of the four side surfaces of the rectangular solid shape of the housing 5, as in the case of I. Therefore, the natural frequency of the housing 5 to the horizontal vibration is increased as a whole.

2. Second Example Embodiment

2-1. Configuration of Fan Motor

Next, a second example embodiment of the present disclosure will be described. FIG. 13 is a longitudinal cross-sectional view of a fan motor 10B according to the second example embodiment. FIG. 14 is a perspective view of a housing 5B according to the second example embodiment. FIG. 15 is a side view of the housing 5B according to the second example embodiment. In the following description, differences from the first example embodiment will be mainly described, and redundant description will be omitted for parts equivalent to those of the first example embodiment.

As shown in FIG. 13, the fan motor 10B includes a motor 1B, an impeller 4B, and the housing 5B. The motor 1B has a stationary part 2B having a stator 22B, and a rotating part 3B that rotates about a center axis 9B extending vertically. The stationary part 2B is stationary relative to a device in which the fan motor 10B is disposed, and the like. The rotating part 3B is rotatably supported around the center axis 9B extending vertically, with respect to the stationary part 2B. The impeller 4B has a plurality of blades 42B, and rotates together with the rotating part 3B of the motor 1B. The housing 5B is a casing that accommodates at least part of the motor 1B and the impeller 4B therein. The details of the housing 5B will be described later.

2-2. Configuration of Housing

Next, the configuration of the housing 5B will be described.

As shown in FIGS. 14 and 15, the housing 5B has a first housing 55B and a second housing 56B. The second housing 56B is fixed directly or indirectly below the first housing 55B.

The first housing 55B has a rectangular solid shape that opens upward and downward. The first housing 55B has a first cylindrical part 511B and an upper flange part 521B.

The first cylindrical part 511B is a cylindrical part extending in the axial direction from the air intake side (upper side) to the exhaust side (lower side) along the center axis 9B. The first cylindrical part 511B accommodates at least part of the motor 1B and the impeller 4B therein, and surrounds the radially outer side of the impeller 4B in an annular shape. The upper flange part 521B protrudes radially outward from an upper end portion of the first cylindrical part 511B at four places in the circumferential direction of the first cylindrical part 511B.

The second housing 56B has a rectangular solid shape that opens upward and downward. The second housing 56B has a base part 21B, a second cylindrical part 512B, a lower flange part 522B, and one or more base connection parts 53B. The housing 5B may have only the upper flange part 521B of the first housing 55B or the lower flange part 522B.

The base part 21B is a disc-shaped part that is disposed below the stator 22B of the motor 1B and expands in the radial direction. The motor 1B is disposed on the base part 21B. The motor 1B is supported by the base part 21B. The second cylindrical part 512B is a cylindrical part disposed below the first cylindrical part 511B and extending in the axial direction from the air intake side (upper side) to the exhaust side (lower side) along the center axis 9B. The second cylindrical part 512B accommodates at least part of the motor 1B and the impeller 4B therein, and surrounds the radially outer side of the impeller 4B in an annular shape. The second cylindrical part 512B is continuously disposed below the first cylindrical part 511B via a contact surface 513B with the first cylindrical part 511B. The lower flange part 522B protrudes radially outward from the lower end portion of the second cylindrical part 512B at four places in the circumferential direction of the second cylindrical part 512B.

The outer shape of the housing 5 having a rectangular solid shape that opens upward and downward is formed by the upper surface and the outer peripheral surface of the upper flange part 521B of the first housing 55B and the lower surface and the outer peripheral surface of the lower flange part 522B. Further, in the present example embodiment, the thickness in the axial direction of the upper flange part 521B and the thickness in the axial direction of the lower flange part 522B are equal to each other.

The base connection part 53B is a columnar part that extends radially outward from at least a portion of the outer peripheral surface of the base part 21B, and is coupled to at least a portion of the inner peripheral surface of the second cylindrical part 512B. Thereby, the position of the stationary part 2B of the motor 1B with respect to the housing 5B is fixed. Further, by providing the base connection part 53B, the lower portion of the second cylindrical part 512B and the lower flange part 522B have higher rigidity than that of the upper portion of the first cylindrical part 511B and the upper flange part 521B. Note that one or more base connection parts 53B are provided in the lower portion of the housing 5B. However, the number of base connection parts 53B is not limited.

Furthermore, the housing 5B has a columnar first rib 541B and a columnar second rib 542B. The first rib 541B extends downward from the upper flange part 521B on the outer peripheral surface of the first cylindrical part 511B. The second rib 542B extends upward from the lower flange part 522B on the outer peripheral surface of the second cylindrical part 512B. One or more of the first ribs 541B and the second ribs 542B are provided. The details of the first rib 541B and the second rib 542B will be described later. The housing 5B may have a structure having only at least one of the first rib 541B and the second rib 542B. Further, in the present example embodiment, the first cylindrical part 511B, the upper flange part 521B, and one or more first ribs 541B are formed as a single member by resin injection molding. However, these may be separate members. Further, in the present example embodiment, the base part 21B, the second cylindrical part 512B, the lower flange part 522B, one or more base connection parts 53B, and one or more second ribs 542B are formed as a single member by resin injection molding. However, these may be separate members.

2-3. Configuration of First Rib and Second Rib

Next, configurations of the first rib 541B and the second rib 542B will be described.

Each of one or more columnar first ribs 541B is located on the outer peripheral surface of the first cylindrical part 511B, and extends downward from the upper flange part 521B in a direction inclined against the axial direction. In addition, each of one or more columnar second ribs 542B is located on the outer peripheral surface of the second cylindrical part 512B, and extends upward from the lower flange part 522B in a direction inclined against the axial direction. With the first rib 541B and the second rib 542B, the rigidity of the housing 5B is increased, and the natural frequency of the housing 5B to the horizontal vibration is increased. As a result, when the fan motor 10B is driven, the resonance amplitude at the time of resonance with the magnetic excitation can be reduced, and noise can be reduced.

In the present example embodiment, the first rib 541B is inclined in a direction away from the center axis 9B toward the upper surface of the housing 5B. The second rib 542B is inclined in a direction away from the center axis 9B toward the lower surface of the housing 5B. As in the first example embodiment, the rigidity of each part of the housing 5B decreases as it goes away to the radially outer side from the center axis 9B. For example, an end portion on the radially outer side of the upper flange part 521B and an end portion on the radially outer side of the lower flange part 522B have particularly low rigidity in the housing 5B. With the first rib 541B and the second rib 542B being provided, these portions are connected to a portion of the housing 5B on the radially inner side of the housing 5B in which the rigidity is high. As a result, the rigidity of the housing 5B as a whole is increased, and the natural frequency is increased. As a result, when the fan motor 10B is driven, the resonance amplitude at the time of resonance with the magnetic excitation can be reduced, and noise can be reduced.

The thickness of each of the first rib 541B and the second rib 542B is preferably equal to or less than the thickness in the axial direction of the upper flange part 521B or the lower flange part 522B. Further, it is desirable that the thicknesses of the first ribs 541B and that of the second ribs 542B are substantially the same. Thereby, similarly to the first example embodiment, at the time of resin molding of the housing 5B including the first rib 541B and the second rib 542B, it is possible to increase the rigidity of the housing 5B and to suppress the noise at the time of driving the fan motor 10B, while suppressing generation of a sink mark.

It is desirable that the lower end portion of each of the one or more first ribs 541B and the upper end portion of each of the one or more second ribs 542B are disposed continuously to each other on the contact surface 513B between the first cylindrical part 511B and the second cylindrical part 512B. As a result, the rigidity of the first rib 541B and the second rib 542B is increased, and the rigidity of the housing 5B as a whole can be further increased.

Furthermore, as in the first example embodiment, when two or more first ribs 541B are provided to each of two side surfaces of the four side surfaces of the rectangular solid shape of the first housing 55B, it is desirable to provide the first rib 541B to two side surfaces adjacent to each other. Thereby, the natural frequency of the first housing 55B to the horizontal vibration can be further increased. When two or more second ribs 542B are provided to each of two side surfaces of the four side surfaces of the rectangular solid shape of the second housing 56B, it is desirable to provide the second ribs 542B to two side surfaces adjacent to each other. This can further increase the natural frequency of the second housing 56B with respect to the horizontal vibration.

FIG. 16 is a diagram showing a result of analyzing the relationship between the positions of the first rib 541B and the second rib 542B and the natural frequency of the housing 5B to the horizontal vibration. The vertical axis represents an analysis result of the natural frequency of each housing 5B based on the analysis result of the natural frequency of the housing 5B of A. In FIG. 16, A represents a result of analyzing the natural frequency of the housing 5B to the horizontal vibration in the case where the first rib 541B is not provided to the first housing 55B and the second rib 542B is not provided to the second housing 56B. B represents a result of a similar analysis in the case where two first ribs 541B are provided to each of the four side surfaces of the rectangular solid shape of the first housing 55B. The second rib 542B is not provided to the second housing 56B. C represents a result of a similar analysis in the case where two second ribs 542B are provided to each of the four side surfaces of the rectangular solid shape of the second housing 56B. The first rib 541B is not provided to the first housing 55B. D and E represent results of similar analyses in the case where one first rib 541B is provided to each of the four side surfaces of the rectangular solid shape of the first housing 55B, and one second rib 542B is provided to each of the four side surfaces of the rectangular solid shape of the second housing 56B. However, in the case of D, the lower end portion of the first rib 541B and the upper end portion of the second rib 542B continues on the contact surface 513B. In the case of E, the first rib 541B and the second rib 542B are provided at positions which do not continue on the contact surface 513B. F represents a result of a similar analysis in the case where two first ribs 541B are provided to all of the four side surfaces of the rectangular solid shape of the first housing 55B, and two second ribs 542B are provided to all of the four side surfaces of the rectangular solid shape of the second housing 56B. FIGS. 17A, 17B, 17C, 17D, 17E, and 17F show top views of the housings 5B of A, B, C, D, E, and F, respectively, for reference. The first ribs 541B are provided at the positions of black circles in the top view of each first housing 55B. In addition, the second ribs 542B are provided at the positions of black circles in the top view of each second housing 56B.

As shown in FIG. 16, when the analysis results of A, B, C, D, E, and F are compared, F has the highest natural frequency of the housing 5 to the horizontal vibration. In the case of F, two first ribs 541B are provided to all of the four side surfaces of the rectangular solid shape of the first housing 55B, and two second ribs 542B are provided to all of the four side surfaces of the rectangular solid shape of the second housing 56B. Therefore, the rigidity of the housing 5B as a whole is increased, and the natural frequency is increased. As a result, when the fan motor 10B is driven, the resonance amplitude at the time of resonance with the magnetic excitation can be reduced, and noise can be reduced. That is, it is desirable that two or more first ribs 541B are provided to each of the four side surfaces of the rectangular solid shape of the first housing 55B, and that two or more second ribs 542B are provided to each of the four side surfaces of the rectangular solid shape of the second housing 56B.

When the analysis results of B and C in FIG. 16 are compared, B has a higher natural frequency of the housing 5B to the horizontal vibration than that of C. In the case of B, a portion on the radially outer side of the upper flange part 521B having particularly low rigidity in the housing 5B is connected to a portion of the radially inner side of the contact surface 513B having high rigidity by the first rib 541B, so that the rigidity of the housing 5B as a whole is increased and the natural frequency is increased. As a result, when the fan motor 10B is driven, the resonance amplitude at the time of resonance with the magnetic excitation can be reduced, and noise can be reduced. That is, in the case where a rib (the first rib 541B or the second rib 542B) is provided to any one of the first housing 55B and the second housing 56B, it is desirable that each of the four side surfaces in the rectangular solid shape of the first housing 55B has only the first rib 541B.

3. Modified Example

While the example embodiments of the present disclosure have been described above, the present disclosure is not limited to the example embodiments described above.

The thickness of each rib may not necessarily be constant. For example, the thickness of the rib may be changed depending on the axial position. Also, two or more ribs may be provided to each of the four side surfaces of the rectangular solid shape of the housing. Moreover, each rib may not necessarily be linear.

Furthermore, the detailed shapes of the respective parts may be different from the shapes shown in the respective drawings of the present application. In addition, the elements that appear in the above-described example embodiments and the modified examples may also be appropriately combined in a range in which there is no contradiction.

The present disclosure is applicable to, for example, a fan motor.

While example embodiments of the present disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The scope of the present disclosure, therefore, is to be determined solely by the following claims.

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