FAN SYSTEM AND SOUND SUPPRESSION METHOD THEREOF

A fan system is used for dissipating heat of an electronic device. The fan system includes a fan, a hollow structure, and a control circuit. Sound waves made by the fan are transmitted to an interior of the hollow structure when the fan is operating. The control circuit is connected to the hollow structure and is configured to control deformation/deformations of the hollow structure according to a state/states of the fan and/or the electronic device, which change a volume of the interior of the hollow structure for making a resonance frequency of the hollow structure being approximate to a rotation speed of the fan or being the same as the rotation speed of the fan.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 107126742 filed in Taiwan, R.O.C. on Aug. 1, 2018, the entire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

The disclosure relates to a fan system and sound suppression method thereof, more particularly to a fan system and a method for suppressing the noise with different frequency.

BACKGROUND

Conventionally, the fan is often disposed behind the hardware device for the rack mount disposition of the server with high memory capacitance, but the spacing between the fan and the hardware device is decreased as the requirement in spacing usage becomes more and more strict. The read performance and write performance of the hardware device may be effected by the noise frequency generated by the fan in operation. However, the rotation speed of the fan is changed based on the inside temperature of the server, and there will be various noise frequencies due to the different rotation speeds. As a result, it's difficult to suppress the noise generated by the fan.

For these reasons, it presently needs a preferable fan system to improve the above problems.

SUMMARY

A fan system is disclosed in an embodiment based on this disclosure, wherein the fan system is for cooling an electronic device, and the fan system comprises: a fan and a hollow structure, wherein the hollow structure in the shape of a neck container, and a sound wave is transmitted to the hollow structure when the fan is operating. There is at least one control circuit connected to the hollow structure, and the at least one control circuit connected to the hollow structure and configured to control a deformation degree of the hollow structure based on an operation state of at least one of the fan and the electronic device. Hence, the volume of the hollow structure may be changed for making the resonance frequency of the hollow structure approximate or even equal to a rotation frequency of the fan.

A fan system is disclosed in an embodiment based on this disclosure, wherein the fan system is for cooling an electronic device, and the fan system comprises: a fan; a body surrounding the fan, wherein an interior face of the body faces the fan and the interior face is spaced from the fan. In addition, the interior face comprises a groove, and the fan transmits a sound wave to the groove. Also, there is a control circuit connected to the body, and the control circuit controls the deformation of the body based on the operation state from at least one of the fan and the electronic device for changing the volume of the groove.

A fan system is disclosed in an embodiment based on this disclosure, wherein the fan system is applied to dissipate the heat from an electronic device, and the fan system comprises: a fan; a body surrounding the fan, and the body comprises an interior face and a side face is next to the interior face, wherein the interior face faces the fan and the interior face is spaced from the fan. Additionally, the side face comprises a groove, and a sound wave is transmitted to the groove when the fan is operating. Moreover, there's a control circuit connected to the body, wherein the control circuit controls the deformation of the body based on the operation state from at least one of the fan and the electronic device for changing the volume of the groove.

A sound suppression method for the fan system is disclosed in an embodiment based on this disclosure, wherein the fan system comprises a fan and a hollow structure, and the sound suppression method comprises: transmitting a sound wave to an interior of the hollow structure by the operating of the fan, detecting the operation state from at least one of the fan and an electronic device, controlling the deformation of the hollow structure to change the volume of the interior of the hollow structure based on the operation state from at least one of the fan and an electronic device, and finally making the resonance frequency of the hollow structure approximate to or even equal to a rotation frequency of the fan.

DETAILED DESCRIPTION

Please refer toFIG. 1.FIG. 1is the schematic diagram of the fan system disposed in the server in an embodiment. AsFIG. 1shows, a server100comprises a fan system102, a hardware device104, a central processor unit106, a temperature sensor108and a circuit board110. The fan system102comprises a fan112and a sound suppressing device114, and the sound suppressing device114is connected between the fan112and the hardware device104. The fan112, the hardware device104and the temperature sensor108are electrically connected to the circuit board110, wherein the temperature sensor108detects the inside temperature of the server100, and the sound suppressing device114is electrically connected to the circuit board110by an external wire116.

Furthermore, there is no limitation for the quantity of the sound suppressing device. For an example of two sound suppressing devices, one of the sound suppressing devices may be disposed between the fan and the hardware device, and another one of them may be disposed between the fan and other electronic devices in the server.

Please refer toFIG. 1andFIG. 2.FIG. 2is the schematic diagram of the fan system based onFIG. 1in the first embodiment. AsFIG. 1andFIG. 2show, the sound suppressing device114comprises a hollow structure118and a channel120communicated with the hollow structure118. In addition, the hollow structure118is an integrally formed shell in the shape of a neck container, and the hollow structure118comprises a body122and a neck124. Also, the body122and the neck124comprise a thickness T1, wherein the bottom of the body122is connected to the top of the neck124for surrounding and forming an interior126of the hollow structure118. In this embodiment, the hollow structure118is a resonator, the bottom of the neck124includes an opening128, and the channel120is formed by a top wall130and a bottom wall132. Moreover, the top wall130is connected around the opening128of the neck124, the two ends of the channel120are respectively extended to the fan112and the hardware device104, and the channel120is communicated with the interior126through the opening128of the neck124. The body122has a width W1and the neck124has a width W2both in the x-axis direction, and the width W2of the neck is smaller than the width W1of the body122. There's no limitation for the shapes of the body122and the neck124. For example, the shape may be a rectangle or a cylinder, but it must meet the criteria, “the width W2smaller than the width W1”. As a result, the hollow structure118in this embodiment is able to be replaced by any other kinds of hollow structures.

Generally, when the shape of a normal metal or alloy is changed by an external force which is out of the elastic range, its shape isn't able to be restored by releasing the external force or heating. In this embodiment, the material of the body122and the neck124is shape memory alloy, wherein the shape memory alloy is a kind of alloy memorizing the original shape according to the changing phase. When the shape memory alloy in the low temperature phase (martensite phase) is deformed by an external force that is limited but larger than the elastic range thereof, the shape is able to be restored by being heated over the critical temperature for transforming to the structure in the high temperature phase (austenite phase). For example, the shape memory alloy may be the alloy of TiNi series, Cu series or Fe series.

The fan system102further comprises a plurality of control circuits134, the control circuits134are respectively embed in the body122and the neck124, and each of the control circuits134is electrically connected to the circuit board110by the wire116for obtaining the rotation speed information of the fan112and the temperature information detected by the temperature sensor108in the server100. Moreover, each of the control circuits134determines whether heats the body122and/or the neck124based on the above information. In other embodiment, the control circuit134is embed in the body122or the neck124.

Please refer toFIG. 3, whereinFIG. 3is the schematic diagram of the hollow structure based onFIG. 2for decreasing the noise. AsFIG. 3shows, the inward sound wave S1enters the interior126of the hollow structure118, and the outward sound wave S2enters the channel120after the outward sound wave S2leaves the interior126. Based on the Helmholtz resonance formula, the resonance frequency of the hollow structure118is shown as the following formula (1):

In the above formula (1), “f” is the resonance frequency of the hollow structure118, “c” is the speed of sound, “A” is the cross area of the neck124, “L” is the length of the neck124, and “V” is the volume of the interior126. In other word, the resonance frequency f is relative to the cross area A of the neck124, the length L of the neck124and the volume V of the interior126.

The absorption coefficient (∝) of the hollow structure118is relative to the absorption ability of the hollow structure118, and the absorption coefficient (∝) is shown as the following formula (2):

In the above formula (2), “Ei” is the energy of the inward sound wave S1, and “Er” is the energy of the outward sound wave S2. Therefore, “Ei-Er” is the sound energy absorbed by the hollow structure118, while the absorption coefficient (∝) is between 0 to 1. The more the absorption coefficient (∝) approximates to 1, the better the absorption ability of the hollow structure118is. Additionally, the absorption coefficient (∝) approximates to 1 when the resonance frequency of the hollow structure118approximates to the frequency of the inward sound wave S1generated by the operating fan112, and the sound volume is decreased obviously after the phase cancellation against the inward sound wave S1entering the interior126.

Please refer toFIG. 1andFIG. 4, whereinFIG. 4is the schematic diagram of the volume changed in the interior of the hollow structure. AsFIG. 1andFIG. 4show, based on the Helmholtz resonance formula, the resonance frequency is changed as one of the cross area A of the neck124, the length L of the neck124and the volume V of the interior126is changed. Hence, through heating the hollow structure118by the control circuit134to increase the thickness of the shape memory alloy from T1to T2, the volume V of the interior126is decreased. In short, based on the Helmholtz resonance formula, the resonance frequency is increased when the volume V of the interior126is decreased. In contrast, the resonance frequency is decreased when the volume V of the interior126is increased.

Please refer toFIG. 5.FIG. 5is the schematic diagram of the fan system based onFIG. 1in the second embodiment. AsFIG. 5shows, the interior126of the sound suppressing device114comprises a plurality of shape memory alloy planes136connected to each other instead of an integrally formed structure, and the control circuit134is embedded in the shape memory alloy planes136and the neck124.

Please refer toFIG. 6, whereinFIG. 6is the schematic diagram of the fan system based onFIG. 1in the third embodiment. AsFIG. 6shows, the neck124of the hollow structure118from the sound suppressing device114comprises a plurality of shape memory alloy planes136connected to each other instead of an integrally formed structure, and the control circuit134is embedded in the shape memory alloy planes136and the neck124.

Please refer toFIG. 1andFIG. 7together, whereinFIG. 7is the flowchart of the sound suppression method for the fan system based onFIG. 1. AsFIG. 1andFIG. 7show, the step S101is transmitting the sound waves to the interior126by the operation of the fan112. The step of S102is detecting the inside temperature of the server by the temperature sensor108. The step S103is transmitting a temperature signal to the central processor unit106by the temperature sensor108. The step S104-1is transmitting the temperature signal to the fan112by the central processor unit106, and the step S104-2is transmitting the temperature signal to the control circuit134by the central processor unit106. The step S105is changing the rotation speed of the fan112according to the temperature signal by the fan. For the step S106, the control circuit134controls the thickness of the shape memory alloy of the hollow structure118for changing the volume of the interior126, and making the resonance frequency of the hollow structure118approximate to or even equal to the rotation frequency of the fan112.

The rotation speed of the fan112is changed as the inside temperature of the server100is changed, and the fan112includes the rotation frequency corresponded to the rotation speed. The fan112generates the sound wave signals with low frequency when the fan112operates in the low rotation speed, and the fan112generates sound wave signals with high frequency when the fan112operates in the high rotation speed. AsFIG. 7shows, the control circuit134increases the thickness of the shape memory alloy by heating the shape memory alloy of the hollow structure118when the rotation speed of the fan112is gained. Hence, the volume of the interior126is decreased, and the resonance frequency of the hollow structure118is increased through this process. If the rotation speed of the fan112is decreased as the fan112operates for a time period, the control circuit134heats the shape memory alloy of the hollow structure118and makes the temperature of the shape memory alloy be more than its critical temperature. As a result, the shape memory alloy is transformed to the structure of the high temperature phase (austenite phase), and making both of the volume of the interior126and the resonance frequency of the hollow structure118return to the original states.

The hollow structure in this disclosure is able to be replaced by other structures for implementation of the sound suppression method. Please refer toFIG. 8.FIG. 8is the schematic diagram of the fan system disposed in the server in another embodiment for this disclosure. AsFIG. 8shows, a server200comprises a fan system202, a hardware device204, a central processor unit206, a temperature sensor208and a circuit board210. The fan system202comprises a fan212and a body214, wherein the body214surrounds the fan, and the fan system202is disposed at a side of the hardware device204. The fan212, the hardware device204, the central processor unit206, and the temperature sensor208are electrically connected to the circuit board210. Also, the body214is electrically connected to the circuit board210by an external wire216, and the temperature sensor208detects the inside temperature of the server200.

Please refer toFIG. 8andFIG. 9Atogether, whereinFIG. 8andFIG. 9Aare the schematic diagrams of the fan system in the first embodiment. AsFIG. 8andFIG. 9Ashow, the body214of the fan system202is a frame made by the shape memory alloy, wherein the body214surrounds the fan212and the body214is spaced from the fan212in the y-axis direction. The fan212comprises a motor218and two blades220and222, and the two blades220and222are respectively connected to the two sides of the motor218. The body214comprises an interior face224, and the interior face224is spaced from the two blades220and222. A plurality of grooves226are disposed in the interior face224, and the grooves226are separated by a plurality of intervals. Also, each of the grooves226has a width W3in the x-axis direction and a depth H1in the y-axis direction. When the motor218turns the two blades220and222, the airflow is driven by the two blades220and222. Moreover, when a kind of the sound wave called wind noise is generated during the air flows through the fan212and the body214, the sound wave resulting in the wind noise generated by the operating fan212is transmitted to the grooves226. Additionally, the fan system202includes a plurality of control circuits228respectively embed in the body214, and each of the control circuits228controls the deformation of the body214based on the operating state of the fan212. As a result, the volume of the body214and the groove226may be changed by this process.

FIG. 9Bis the top view fromFIG. 9A. AsFIG. 9Bshows, the grooves226arranged between the intervals are disposed in the body214in the X-Z plane, and the grooves226are in the shapes of squares with the same length for each side.

Please refer toFIG. 10, whereinFIG. 10is the top view based on the fan system inFIG. 8in the second embodiment. AsFIG. 10shows, the grooves230arranged between the intervals are disposed on the body214in the X-Z plane, and the grooves230may be in square, rectangle, circle, triangle, pentagon and hexagon shapes.

Please refer toFIG. 11, whereinFIG. 11is the schematic diagram of the fan system based onFIG. 8in the third embodiment. AsFIG. 11shows, the interior face224comprises a plurality of the grooves232arranged between the intervals, wherein each of the grooves232comprises a first section234and a second section236in the y-axis direction, and the interior face224is closer to the first section234than to the second section236. Also, the first section234has a width W4and the second section236has a width W5both in the x-axis direction, and the width W4is smaller than the width W5. The sound wave with the wind noise is transmitted to the grooves232when the fan212is operating, and each of the control circuits228controls the deformation of the body214based on the operating state of the fan212. As a result, the volume of the groove232disposed in the body214is able to be changed by this process.

Please refer toFIG. 12, whereinFIG. 12is the schematic diagram of the fan system based onFIG. 8in the fourth embodiment. AsFIG. 12shows, the body214of the fan system202comprises the interior face224and two side faces238and240which are next to the interior face224. In addition, the interior face224faces the fan212and the interior face224is spaced from the fan212, wherein there is a plurality of grooves242disposed in each of the two side faces238and240, and the sound wave with the wind noise generated by the operating fan212is transmitted to the grooves242. Also, each of the grooves242comprises a first section244and a second section246in the x-axis direction, and the side face238is closer to the first section244than to the second section246. Moreover, the first section244has a width W6and the second section246has a width W7both in the y-axis direction, wherein the width W6is smaller than the width W7. As a result, each of the control circuits228controls the deformation of the body214based on the operating state of the fan212, and the volume of the groove242disposed in the body214is able to be changed by this process.

Please refer toFIG. 13, whereinFIG. 13is the schematic diagram for suppressing the noise of the fan system based onFIG. 9A. When the fan212operates at different rotation speeds, the space between the fan212and the bottom of the groove226needs to be adjusted for suppressing the wind noise. For this reason, after the control circuit228adjusts the volume of the groove226to a proper value, the inward airflow S3generated by the operating fan212enters the groove226of the body214and then is reflected therefrom. Finally, the sound volume generated by the outward airflow S4reflected from the groove226is lower than the sound volume generated by the inward airflow S3.

Please refer toFIG. 8andFIG. 14together, whereinFIG. 14is the flowchart for the sound suppression method of the fan system based onFIG. 8. AsFIG. 8andFIG. 14show, the step S201is transmitting the sound waves generated by the operation of the fan to the groove226of the body214. The step S202is detecting the inside temperature of the server200by the temperature sensor208. The step S203is transmitting a temperature signal to the central processor unit206by the temperature sensor208. The step S204-1is transmitting the temperature signal to the fan212by the central processor unit206, and the step S204-2is transmitting the temperature signal to the control circuit228by the central processor unit206. The step S205is changing the rotation frequency of the fan212according to the temperature signal by the fan212. The step S206is controlling the thickness of the shape memory alloy of the body214based on the temperature signal by the control circuit228for changing the volume of the groove226of the body as well as decreasing the energy of the sound wave by making the sound wave reflect in the groove226when the fan212is operating.

When the inside temperature of the server200is changed, the rotation speed of the fan212is relatively changed, and the fan112includes the rotation frequency corresponded to the rotation speed. The fan212generates the sound wave with the low frequency when the fan212rotates in the low rotation speed, and the fan212generates the sound wave with the high frequency when the fan212rotates in the high rotation speed. AsFIG. 14shows, as the rotation speed of thee fan212is increased, the thickness of the shape memory alloy is raised through heating the shape memory alloy of the body214by the control circuit228, and the volume of the groove226of the body214is decreased. Hence, the space of the groove226is smaller than the original space, and the reflection effect of the sound wave in high frequency is improved. If the rotation speed of the fan212is decreased as the fan212rotates for a time period, the control circuit228heats the shape memory alloy of the body214until the temperature of the body is more than the critical temperature of the shape memory alloy. Thus, the structure of the shape memory alloy is transformed to the high temperature phase (austenite phase) for returning to the original state. As a result, the volume of the groove226is returned to the original volume, and the space of the groove226is larger than the original space, so the reflection effect of the sound wave in low frequency is improved.

Based on the fan system disclosed in this disclosure, in addition to maintenance of the normal airflow between the hardware device and the fan system, by the properties of the shape memory alloy and the control circuit, the control circuit is able to change the volume of the groove based on the rotation frequency of the fan and/or the temperature of the electronic device. Hence, even though the fan may operate at different rotation speeds, the resonance frequency of the groove is able to approximate or even equal to the rotation frequency of the fan. As a result, the sound volume generated by the operating fan can be decreased during this process. On the other hand, by changing the thickness of the body appropriately through the control circuit, the space between the fan and the bottom of the groove is able to be maintained in a proper value, and the wind noise is suppressed by this process.

The embodiments depicted above and the appended drawings are exemplary and are not intended to be exhaustive or to limit the scope of the present disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings.