COUNTER-ROTATING FAN
A counter-rotating fan includes a first fan including a first impeller including first blades radially arranged around a predetermined center axis, a first motor that rotates the first impeller around the center axis, and a first case surrounding an outer circumference of the first impeller, and a second fan including a second impeller including second blades radially arranged around the center axis, a second motor that rotates the second impeller around the center axis, and a second case surrounding an outer circumference of the second impeller. The first blades include a front edge located foremost in a rotation direction and a rear edge located rearmost in the rotation direction. A radially outermost end of the rear edge is located closer to the second fan than a radially innermost end.
This application claims the benefit of priority to Japanese Patent Application No. 2018-069445 filed on Mar. 30, 2018. The entire contents of this application are hereby incorporated herein by reference.
BACKGROUND OF THE INVENTION 1. Field of the InventionThe present disclosure relates to a counter-rotating fan.
2. Description of the Related ArtConventionally, in electronic devices such as personal computers and servers, a cooling fan is used to cool electronic components in a housing. A serial axial fan in which two air blowing units are connected in series along a predetermined center axis is known as one of such cooling fans. This serial axial fan is formed by arraying two impellers rotating in directions opposite to each other in a direction of the center axis.
A cooling fan having a larger air volume is required in a relatively large electronic device such as a server. For this reason, there is a demand for providing a new technique capable of obtaining the larger air volume even in a counter-rotating fan that is one type of the serial axial fan.
SUMMARY OF THE INVENTIONAccording to an illustrative embodiment of the present disclosure, a counter-rotating fan includes a first fan including a first impeller including a plurality of first blades radially arranged around a predetermined center axis, a first motor that rotates the first impeller around the center axis, and a first case surrounding an outer circumference of the first impeller, and a second fan including a second impeller including a plurality of second blades radially arranged around the center axis, a second motor that rotates the second impeller around the center axis, and a second case surrounding an outer circumference of the second impeller. The plurality of first blades include a front edge located foremost in a rotation direction and a rear edge located rearmost in the rotation direction. A radially outermost end of the rear edge is located closer to the second fan than a radially innermost end.
The illustrative embodiment of the present disclosure provides a counter-rotating fan having larger air volume.
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 illustrative embodiments with reference to the attached drawings.
Hereinafter, illustrative embodiments of the present disclosure will be described with reference to the drawings. The scope of the present disclosure is not limited to the illustrative embodiments described below, but any change can be made within the scope of the technical idea of the present disclosure.
Sometimes a scale, a number, and the like of a structure in the following drawings differ from those of an actual structure for the sake of easier understanding of the members or portions. In each drawing, a Z-axis is illustrated as appropriate. A Z-axis direction in each drawing is a direction parallel to the axial direction of a center axis J in
For example, a counter-rotating fan 100 according to the embodiment is used as an electric type cooling fan that air-cools an electronic device such as a server.
As illustrated in
In the counter-rotating fan 100, a first impeller 10 of the first axial fan 1 and a second impeller 20 of the second axial fan 2 rotate in directions opposite to each other, whereby air is taken from the left side in
In the counter-rotating fan 100, by setting a rotation direction of the first impeller 10 and a rotation direction of the second impeller 20 in opposite directions, a high static pressure and a large air volume can be achieved as compared with the serial axial fan in which the two impellers rotate in the same direction.
As illustrated in
The first impeller 10 includes a plurality (in the embodiment, five) of first blades 10a radially arranged at equal pitches around the center axis J. The first impeller 10 rotates in a predetermined direction (the direction of an arrow illustrated in
The second impeller 20 includes a plurality (in the embodiment, three) of second blades 20a radially arranged at equal pitches around the center axis J. The second impeller 20 rotates around the center axis J by the second motor 21 in a direction opposite to the direction of the first impeller 10 (the direction of an arrow in
The first case 12 surrounds the outer circumference (radial outside) of the first impeller 10. In the embodiment, for example, the first case 12 is formed by aluminum die casting. The first case 12 includes a peripheral wall 12A having a tubular shape and extending in the axial direction, four intake-side flanges 12B provided on the intake side in the axial direction of the peripheral wall 12A and protruding toward the radial outside, and four exhaust-side flanges 12C provided on the exhaust side in the axial direction of the peripheral wall 12A and protruding toward the radial outside.
The first case 12 constitutes a wind tunnel by an inner peripheral surface 12A1 formed of a cylindrical surface in the peripheral wall 12A. As illustrated in
As illustrated in
As illustrated in
As illustrated in
The configuration of the first motor 11 will be described later.
The second case 22 surrounds the outer circumference (radial outside) of the second impeller 20. In the embodiment, the second case 22 includes a peripheral wall 22A having a tubular shape and extending in the axial direction, four intake-side flanges 22B provided on the intake side in the axial direction of the peripheral wall 22A and protruding toward the radial outside, and four exhaust-side flanges 22C provided on the exhaust side in the axial direction of the peripheral wall 22A and protruding toward the radial outside.
The second case 22 constitutes a wind tunnel by an inner peripheral surface 22A1 formed of a cylindrical surface in the peripheral wall 22A. As illustrated in
As illustrated in
As illustrated in
The plurality of second support ribs 23 (in the embodiment, four) extend radially around the center axis J, are connected to the second case 22, and support the side of the first motor 11 of the second motor 21.
Specifically, the second support rib 23 is located on the intake side of the inner peripheral surface 22A1 in the peripheral wall 22A of the second case 22, and supports the radial outside of the second motor 21. The configuration of the second motor 21 will be described later.
The first case 12 and the second case 22 are disposed such that the first notch 14 of the exhaust-side flange 12C of the first case 12 and the second notch 15 of the intake-side flange 22B of the second case 22 are aligned (see
As illustrated in
As illustrated in
The first circuit board 33 is held by being inserted into the bearing holder 30b of the stator 30. The first circuit board 33 has a substantially annular plate shape, is electrically connected to a lead wire (not illustrated) drawn from the coil 30d of the stator 30, and controls the rotation of the stator 30. The first circuit board 33 is disposed on the side of the second axial fan 2 of the stator 30. For example, an integrated circuit and a capacitor (not illustrated) are mounted on the first circuit board 33. A first wiring 34 (see
The first circuit board 33 is connected to an external device (not illustrated), such as a power supply, which is provided outside the counter-rotating fan 100, through the first wiring 34.
As illustrated in
The rotor 31 is rotatably journaled around the center axis J through the bearing 32 with respect to the stator 30. The rotor 31 includes a core 31a made of metal and having magnetism and a substantially covered cylindrical shape centered on the center axis J, a magnet 31b that has a substantially cylindrical shape and is opposed to the coil 30d of the stator 30 while fixed to the inside (that is, the inside surface) of a side wall of the core 31a, a shaft 31c protruding in the axial direction from a cover of the core 31a, and a bush 31d.
The shaft 31c is rotatably journaled through the bearing 32 while inserted into the bearing holder 30b. In the rotor 31, the core 31a and the shaft 31c are integrally held with the bush 31d interposed therebetween. The first impeller 10 is fixed to the rotor 31 with the bush 31d interposed therebetween. Consequently, the first impeller 10 is rotatable together with the rotor 31.
As illustrated in
The rotor 41 is rotatably journaled around the center axis J through the bearing 42 with respect to the stator 40. The rotor 41 includes a core 41a made of metal and having magnetism and a substantially covered cylindrical shape centered on the center axis J, a magnet 41b that has a substantially cylindrical shape and is opposed to the coil 40d of the stator 40 while fixed to the inside (that is, the inside surface) of a side wall of the core 41a, a shaft 41c protruding in the axial direction from a cover of the core 41a, and a bush 41d.
The shaft 41c is rotatably journaled through the bearing 42 while inserted into the bearing holder 40b. In the rotor 41, the core 41a and the shaft 41c are integrally held with the bush 41d interposed therebetween. The second impeller 20 is fixed to the rotor 41 with the bush 41d interposed therebetween. Consequently, the second impeller 20 is rotatable together with the rotor 41.
The second support rib 23 extends radially from the base 40a, and is connected to the inner peripheral surface 22A1 of the peripheral wall 22A of the second case 22. In the embodiment, the base 40a and the bearing holder 40b are made of aluminum similarly to the second case 22. That is, the base 40a and the bearing holder 40b are integrally formed by aluminum die casting together with the plurality of second support ribs 23 and the second case 22. Two bearings 42, which are a part of a bearing mechanism, are provided inside the bearing holder 40b in the axial direction.
The second circuit board 43 is held by being inserted into the bearing holder 40b of the stator 40. The second circuit board 43 has a substantially annular plate shape, is electrically connected to a lead wire (not illustrated) drawn from the coil 40d of the stator 40, and controls the rotation of the stator 40. The second circuit board 43 is disposed on the side of the first axial fan 1 of the stator 40. For example, an integrated circuit and a capacitor (not illustrated) are mounted on the second circuit board 43. A second wiring 44 (see
As illustrated in
In the embodiment, the first notch 14 and the second notch 15 overlap each other in a planar manner when viewed from the axial direction. That is, the drawing direction of the first wiring 34 from the first circuit board 33 is the same as the drawing direction of the second wiring 44 from the second circuit board 43. In the counter-rotating fan 100 of the embodiment, by setting the drawing directions of the first wiring 34 and the second wiring 44 to the same direction, the first wiring 34 and the second wiring 44 can easily be routed to an external device.
The rotor 41 is rotatably journaled around the center axis J through the bearing 42 with respect to the stator 40. The rotor 41 includes the core 41a made of metal and having magnetism and a substantially covered cylindrical shape centered on the center axis J, the magnet 41b that has a substantially cylindrical shape and is opposed to the coil 40d of the stator 40 while fixed to the inside (that is, the inside surface) of the side wall of the core 41a, and the shaft 41c protruding in the axial direction from the cover of the core 41a. The shaft 41c is rotatably journaled through the bearing 42 while inserted into the bearing holder 40b.
When the counter-rotating fan 100 of the embodiment is viewed as a whole, the first case 12 of the first motor 11 and the second case 22 of the second motor 21 contact with each other in the axial direction. In the embodiment, the exhaust-side end surface of the first case 12 and the intake-side end surface of the second case 22 contact with each other in the axial direction. More specifically, the exhaust-side end surface 54 of the peripheral wall 12A of the first case 12 and the intake-side end surface 63 of the peripheral wall 22A of the second case 22 contact with each other in the axial direction.
The surface 12C1 (see
At this point, a position where the first case 12 and the second case 22 contact with each other in the axial direction is referred to as a first position P1. In the embodiment, an end surface of the first case 12 and an end surface of the second case 22 contact with each other at the first position P1 in the axial direction.
In the embodiment, an axial length H1 of the first case 12 is longer than an axial length H2 of the second case 22. Thus, an axial distance of the wind tunnel constructed with the first case 12 is longer than an axial distance of the wind tunnel constructed with the second case 22. In the embodiment, the axial length of the first blade 10a of the first impeller 10 accommodated in the first case 12 can be set longer than the axial length of the second blade 20a of the second impeller 20 accommodated in the second case 22.
In the first axial fan 1 and the second axial fan 2, the end surface located on the exhaust side in the axial direction of the first motor 11 is opposed to the end surface located on the intake side in the axial direction of the second motor 21.
Specifically, the first motor 11 and the second motor 21 are disposed such that the surface 30a1 opposite to the bearing holder 30b in the base 30a and the surface 40a1 opposite to the bearing holder 40b in the base 40a are brought close to each other. That is, a gap is formed between the surface 30a1 and the surface 40a1.
At this point, a position where the first motor 11 and the second motor 21 are opposed to each other in the axial direction is referred to as a second position P2. In the embodiment, the first motor 11 and the second motor 21 are disposed while facing in opposite directions in the axial direction, and the end surfaces (the surface 30a1 and the surface 40a1) of the first motor 11 and the second motor 21 are opposed to each other at the second position P2 different from the first position P1. In the embodiment, because the gap is formed between the surface 30a1 and the surface 40a1, the second position P2 corresponds to the center position in the axial direction of the gap.
Specifically, the second position P2 is located closer to one side in the axial direction (intake side) than the first position P1 is. In the embodiment, because the first motor 11 and the second motor 21 have the same configuration, the first motor 11 and the second motor 21 have the same axial dimension.
The first support rib 13 includes a connection surface 13a (see
The second support rib 23 includes a connection surface 23a (see
In the embodiment, an end surface of the first support rib 13 and an end surface of the second support rib 23 contact with each other in the axial direction. Specifically, in the counter-rotating fan 100, the connection surface 13a of the first support rib 13 and the connection surface 23a of the second support rib 23 contact with each other in the axial direction. The first support rib 13 and the second support rib 23 contact with each other with no gap, so that the first support rib 13 and the second support rib 23 function as a stationary blade 25 in the counter-rotating fan 100. The stationary blade 25 functions as a vane that suppresses the spread of the air delivered from the first impeller 10 in a direction away from the center axis J.
In the counter-rotating fan 100 of the embodiment, by equalizing the sectional areas along the axial direction of the first support rib 13 and the second support rib 23 to each other, generation of misrun can be reduced in forming the first case 12 and the second case 22 by die casting. Thus, high-precision components can be provided as the first case 12 and the second case 22.
As described above, in the counter-rotating fan 100 of the embodiment, the case contact position (first position P1) is different from the motor facing position (second position P2) in the axial direction, so that commonalization of the motor component can be achieved while the size of the first impeller 10 disposed on the intake side is enlarged. Thus, the motor is commonalized, and the first impeller 10 can be designed larger than the second impeller 20, so that the counter-rotating fan 100 that obtains a larger air volume can be provided.
The cost reduction can be achieved by the commonalization of the motor component.
While the embodiment of the present disclosure is described above, features, a combination of the features according to the embodiment are only illustrative, addition, elimination, and substitution of the configuration, and other changes can be made without departing from the scope of the present disclosure. The present disclosure is not limited to the embodiment.
For example, in the counter-rotating fan 100 of the embodiment, the first axial fan 1 is disposed on the intake side while the second axial fan 2 is disposed on the exhaust side. However, the disposition of the first axial fan 1 and the second axial fan 2 is not limited to this configuration. That is, the first axial fan 1 may be disposed on the exhaust side while the second axial fan 2 may be disposed on the intake side.
According to this configuration, the motors of the two fans are commonalized and the wind tunnel distance on the exhaust side is longer than the wind tunnel distance on the intake side. Thus, a counter-rotating fan having a desired air volume characteristic can be provided.
Features of the above-described preferred embodiments and the modifications thereof may be combined appropriately as long as no conflict arises.
While preferred embodiments of the present invention 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 invention. The scope of the present invention, therefore, is to be determined solely by the following claims.
Claims
1. A counter-rotating fan comprising:
- a first fan including a first impeller including a plurality of first blades radially arranged around a predetermined center axis, a first motor that rotates the first impeller around the center axis, and a first case surrounding an outer circumference of the first impeller; and
- a second fan including a second impeller including a plurality of second blades radially arranged around the center axis, a second motor that rotates the second impeller around the center axis, and a second case surrounding an outer circumference of the second impeller; wherein
- the plurality of first blades include a front edge located foremost in a rotation direction and a rear edge located rearmost in the rotation direction; and
- a radially outermost end of the rear edge is located closer to the second fan than a radially innermost end.
2. The counter-rotating fan according to claim 1, wherein when the first motor and the second motor are rotationally driven, air is taken in from a side of the first fan, and delivered to a side of the second fan to generate a flow of air in a direction of the center axis.
3. The counter-rotating fan according to claim 1, wherein the rear edge is moved closer to the second fan from the radially innermost end toward the radially outermost end.
4. The counter-rotating fan according to claim 3, wherein the first fan includes a first case surrounding a radial outside of the first impeller and a plurality of first support ribs that extend radially around the center axis, are connected to the first case, and support the first motor, and an axial gap between the rear edge and an end on a side of the first impeller of each of the first support ribs decreases toward a radially outer region.
5. The counter-rotating fan according to claim 1, wherein
- the first impeller includes a first blade support with a covered cylindrical shape and supporting the plurality of first blades; and
- the radially outermost end of the rear edge is located closer to the second fan than a lower end of the first blade support.
6. The counter-rotating fan according to claim 1, wherein the first motor includes a stator, a rotor, a bearing, and a first circuit board, the first circuit board is disposed on a side of the second fan of the stator, and the radially outermost end of the rear edge is located closer to the second fan than an upper end of the first circuit board.
7. The counter-rotating fan according to claim 1, wherein
- the plurality of second blades include a front edge located foremost in the rotation direction and a rear edge located rearmost in the rotation direction;
- an axial distance between the radially outermost end of the front edge of the plurality of first blades and the radially outermost end of the rear edge is larger than an axial distance between the radially outermost end of the front edge of the plurality of second blades and the radially outermost end of the rear edge.
Type: Application
Filed: Feb 12, 2019
Publication Date: Oct 3, 2019
Inventors: Yoshihiko KATO (Kiryu-shi), Takahiro BAMBA (Kiryu-shi), Yoshihisa KAGAWA (Kiryu-shi), Takanori ABE (Kiryu-shi)
Application Number: 16/273,188