Patent Grant
8647077
This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Electronic devices typically consist of a variety of electrical components. These components may generate substantial amounts of heat that can damage or inhibit the operation of the electronic device. Consequently, electronic devices commonly use cooling fans to remove heat generated within the electronic device by the electrical components.
Exemplary embodiments of the present invention may be apparent upon reading of the following detailed description with reference to the drawings in which:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
Referring generally to
The illustrated server 20 has a chassis 22 that supports the components of the server 20. One of the components of the server 20 that is supported by the chassis 22 is a processor module 24 that houses a plurality of processors. The processor or processors in processor module 24 enable the server 20 to perform its intended functions, such as functioning as a file server or as an application server. To perform these functions, the processor module 24 processes data from various sources. Some of these sources of data are housed within a memory module 26. The memory module 26 may comprise one or more data storage devices that are operable to store data and transmit the data to the processors in the processor module 24. In this embodiment, the data storage devices comprise several hard disk drives 28, a CD-ROM drive 30, and a diskette drive 32. However, the memory module 26 may comprise other data storage devices. The illustrated server 20 also comprises a control panel 34 to enable a user to monitor and control various server functions.
Another component that may be supported by the chassis 22 is an Input/Output (“I/O”) module 36. The I/O module 36 is adapted to receive a plurality of I/O cards 38 for communicating with other computers and electronic devices via a network, such as the Internet. The I/O cards 38 enable data to be transferred between the processor module 24 and external devices via the network. In addition, the illustrated I/O module 36 houses one or more power supplies, such as a pair of power supplies 40. In the illustrated embodiment, the power supplies 40 are redundant, i.e., one of the power supplies 40 is operating at all times and the other power supply is idle, but ready to operate if requested by the server 20. In addition, the power supplies 40 are hot-pluggable, i.e., the power supplies 40 may be removed and installed while the server 20 is operating. In this embodiment, the I/O module 36 has its own chassis 42 that is disposed within the server chassis 22.
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The motor controller 112 has a plurality of electronic components 114 that are mounted on the circuit board 110 and electrically coupled together through the circuit board 110. The circuit board 110 is secured to a hub 116 of the fan housing 70. In this embodiment, the hub 116 is secured to the fan housing 70 by three support arms 118. The motor controller 112 has various inputs and outputs that are electrically coupled to the electrical connector 82 disposed on the bottom 84 of the fan 44, as illustrated in
As illustrated in
The rotor 102 comprises a rare earth magnet 132. In the illustrated embodiment the rare earth magnet 132 is a bonded neodymium-iron-boron magnet and has eight poles. As noted above, the stator 100 produces a rotating magnetic field that induces rotation of the magnet 132. The magnet 132 is secured to the hub 76. Thus, as the magnet 132 rotates, the hub 76 and blades 78 of the impeller 72 rotate. The rotation of the blades 78 of the impeller 72 induces the flow of air through the fan. The bonded neodymium-iron-boron magnet 132 does not produce cogging torque. Cogging torque occurs when the rotor poles try to align with the stator poles. Cogging torque is undesirable it interferes with the rotation of the rotor 102, making the motor 80 less efficient. The bonded neodymium-iron-boron magnet 132 increases the efficiency of the motor by approximately eight percent over a conventional permanent magnet.
Referring generally to
One factor that affects the flow of air that is produced by the impeller 72 is the blade height (“HB”). The height of the blades is limited by the diameter of inner cylindrical portion 74 of the fan housing 70 and the hub diameter (“DH”) of the fan impeller 72. The hub diameter is defined by the size of the motor to be housed therein. The greater efficiency of a three-phase DC motor over a conventional DC motor enables a three-phase motor DC motor to produce the same power as a conventional DC motor but in a smaller volume. In addition, the gap 134 between the outer diameter of the magnet and the inner diameter of the hub 76 also is minimized to reduce the outer diameter of the hub 76. Thus, the hub 76 in the illustrated embodiment is smaller in diameter than a comparable fan that uses a single-phase DC motor. In the illustrated embodiment, the first fan 44 is a 5.5 inch by 5.5 inch cooling fan. However, the present techniques are applicable to fans of all sizes. The impeller diameter (“DI”) in the illustrated embodiment, and in a typical impeller for a 5.5 inch by 5.5 inch cooling fan, is 5.25 inches. In a typical cooling fan using a conventional DC motor, the hub diameter is approximately 3.13 inches. Thus, each blade is approximately 1.06 inches. However, the hub diameter (“DH”) of the illustrated 5.5 inch by 5.5 inch cooling fan is 2.56 inches and the blade height (“HB”) is 1.35 inches long. As a result, the blade height (“HB”) in the illustrated embodiment is approximately 25% of the impeller diameter (“DI”), as compared to 20% of the impeller diameter in a fan using a conventional DC motor. This enables the impeller 72 to displace a greater amount of air for each rotation of the impeller than an impeller of a comparable fan powered by a conventional DC motor.
The shape of the blades 78 in the illustrated embodiment has been established to produce the desired flow characteristics when the fan is operating, but also to minimize resistance to air flow when the fan is idle. Reducing the resistance to air flow increases the efficiency of the system and reduces noise. One of these shape characteristics is the “camber” of the blade. Camber is the amount (in degrees) that the blade turns from the leading edge to the trailing edge. For example, a straight line has zero degrees of camber, while a U-turn has one-hundred-and-eighty degrees of camber. An impeller blade having camber will produce pressure, but not efficiently. Another blade characteristic is “stagger.” Stagger is the blade setting angle, at any radial location, with respect to the axial direction. For example, a blade having a stagger angle of zero degrees would be aligned with the axis of the impeller. A blade having a stagger of ninety degrees would be perpendicular to the axis of the impeller. Stagger controls the quantity of flow that the fan draws. Still another blade characteristic is the “chord.” The chord is the linear distance between the leading edge and the trailing edge. If the blade has any camber, the blade length is larger than the chord. However, if the blade has zero camber, the chord and the length are the same. Finally, a characteristic of the blades of an impeller as a group is the “solidity.” Solidity is the ratio of the chord length to the spacing (“S”) between the blades. The higher the solidity of the impeller, the greater the resistance to air flow when the fan is idle. Preferably, the solidity is from 0.95 to 1.05. In addition, the resistance to air flow greater if the impeller is locked, rather than spinning freely.
In this embodiment, the impeller 72 has seven blades 78 that each have a “fish-shaped” chord profile, i.e., the chord length of each blade increases from the hub 76 to a maximum chord length height (“HMCL”) and then decreases. At the base 136 of the blade 78, the blade 78 has a first chord length (“C1”). In the illustrated embodiment, the first chord length (“C1”) is 1.3 inches. The chord length decreases slightly from the base 136 of the blade 78 to a narrower portion 138 of the blade 78 just above the hub 76. From the narrower portion 138 of the blade 78, the chord increases to the maximum chord length (“C2”) at the widest portion 140 of the blade 78. In the illustrated embodiment, the maximum chord length is 1.8 inches and is at a height (“HMCL”) of 0.64 inches, which is approximately 47 percent of the (“HB”). In this embodiment, the spacing (“S”) between the blades 78 at the maximum chord length height (“HMCL”) is 1.8 inches. Thus, the impeller 72 has a solidity of one at the maximum chord length (“C2”). The low solidity produced by having smaller chords near the hub 76 hinders stall at speeds below 200 CFM. The chord decreases from the widest portion 140 of the blade 78 to the tip 142 of the blade 78. In the illustrated embodiment, the chord length (“C3”) at the tip 142 of the blade 78 is 1.3 inches.
In addition, the stagger of each blade 78 increases from a first stagger angle (“λ1”) at the hub 76 to a second stagger angle (“λ2”) at the tip 142. Preferably, the first stagger angle (“λ1”) is from 24 degrees to 30 degrees and the second stagger angle (“λ2”) is from 50 degrees to 56 degrees. In this embodiment, the stagger of each blade 78 increases from twenty-nine degrees (“λ1”) at the hub 76 to fifty-six degrees (“λ2”) at the tip 142. The camber angle of each blade 78 decreases from the hub 76 to the tip 142. Preferably, the camber angle of each blade 78 at the hub 76 (“θ1”) is from twenty-six degrees to thirty-two degrees and the camber angle (“θ2”) at the tip 142 is from nine degrees to fifteen degrees. In this embodiment, the camber angle of each blade 78 at the hub 76 (“θ1”) is twenty-nine degrees and decreases to twelve degrees at the tip 142 (“θ2”). The camber of the blades 78 minimizes interference between the fan impellers by producing low blade trailing edge angles. The chord profile, the solidity, the stagger angle, and the camber angle may be modified to produce the desired results.
While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
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