Heat disspation device and control method   

Abstract: A heat dissipation device for cooling a heat generating component, includes a fins module, a heat pipe, a fan, at least two temperature sensors, and a control system. The heat pipe includes an evaporation section absorbing heat from the heat generating component, and a condensation section thermally connected to the fins module. The fan is for driving airflow towards the fins module. The at least two temperature sensors are arranged on the evaporation section of the heat pipe, for continuously sensing temperatures of their respective positions on the heat pipe. The control system adjusts the speed of the fan and/or the operating power of the heat generating component according to the sensed temperatures of the at least two temperature sensors. A method for controlling the heat dissipation device is also provided.

1. Technical Field

The present disclosure generally relates to heat dissipation devices, and control method for the heat dissipation devices.

2. Description of Related Art

During operation of electronic devices such as computer central processing units (CPUs), a large amount of heat is often produced. The heat must be quickly removed from the electronic devices to prevent them from becoming unstable or being damaged. Many heat dissipation devices are employed to dissipate heat produced by the electric device. A heat dissipation device generally comprises a base attached to the electric device, a plurality of fins thermally connected to the base by heat pipes, and a fan for driving airflow towards the fins. The base is intimately attached to the CPU for absorbing the heat generated by the CPU. Most of the heat accumulated on the base is transferred to the fins by the heat pipes and then the fins are cooled by airflow driven by the fan.

To achieve high efficiency heat transfer, a fan speed of the heat dissipation device is high, which is not energy saving.

Therefore, what is needed is to provide a heat dissipation device capable of effectively improving heat dissipating efficiency under different temperatures.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the disclosure.

FIG. 1 is a schematic view of a heat dissipation device in accordance with an embodiment of the present disclosure.

FIG. 2 is similar to FIG. 1, but showing another aspect of the heat dissipation device.

FIG. 3 is an exploded view of the heat dissipation device of FIG. 1.

FIG. 4 is a function block diagram of the circuit of the mobile phone of FIG. 1.

FIG. 5 is a plot of the thermal resistance versus the fan speed of the heat dissipation device.

FIG. 6 is a flowchart illustrating a principle of fan speed and processor power adjustment of the heat dissipation device.

DETAILED DESCRIPTION

Reference will now be made to the drawings to describe the present embodiment of a heat dissipation device, in detail.

Referring to FIGS. 1-4, a heat dissipation device 10 according to an embodiment includes a fan 11, a fins module 12, a heat pipe 13, a base 14, two fixing plates 15, and a control system 16.

The fan 11 is for driving airflow towards the fins module 12. The fan 11 includes a housing 111, a hub 112 and a plurality of blades 113 radially and extending outward from the hub 112. The housing 111 defines an air outlet 1111 at a lateral side. The hub 112 and the plurality of blades 113 are received in the housing 111.

The fins module 12 is arranged adjacent to the air outlet 1111. The fins module 12 includes a plurality of fins 121 arranged in parallel to each other. Air channels 122 are formed between each two neighboring fins 121. The fins 121 each define a rectangular through hole 123 with a size matching the heat pipe 13. The through holes 123 of the plurality of fins 121 are arranged in alignment, thereby the heat pipe 13 can penetrate through the plurality of fins 121 via the through holes 123.

The heat pipe 13 has a curved shape with a flat profile. The heat pipe 13 is made of metal pipe with excellent heat conductivity and phase-change media sealed in the metal pipe. The heat pipe 13 includes an evaporation section 131 and a condensation section 132.

The evaporation section 131 of the heat pipe 13 is thermally attached to a central portion of the base 14 and fixed to the base 14 by the fixing plate 15. At least two temperature sensors 133 are arranged at different positions of the evaporation section 131. At the position where each temperature sensor 133 sits, a temperature is sensed, and a sensed result is sent to the control system 16, by the temperature sensor 133. The number of temperature sensors 133 can be two, three, four, or more. In this embodiment, there are three temperature sensors 133 arranged on the evaporation section 131.

The condensation section 132 of the heat pipe 13 is perpendicular to the evaporation section 131 and thermally connected to the fins module 12. In addition, the condensation section 132 penetrates through the plurality of fins 121 via the through holes 123.

The base 14 is a flat heat conductive plate with the four corners cut off. The base 14 has its bottom intimately attached to a processor 17 in use. The base 14 has its top attached to the evaporation section 131 of the heat pipe 13.

The fixing plates 15 each include a central portion 151, a first side portion 152 and a second side portion 153. The central portion 151 is a strip-like portion fixed with the base 14. The first and second side portions 152, 153 respectively extend from an end of the central portion 151 along a direction inclined to the central portion 151. The first and second side portions 152, 153 each include a distal end, in which a through hole 154 is defined. Accordingly, the base 14 can be fixed to a circuit board (not illustrated) by bolts 155 penetrating through the through holes 154. In this embodiment, a plurality of gaskets 156 engage with corresponding bolts 155 under the fixing plates 15.

Referring to FIG. 4, the control system 16 communicates with the processor 17 and the fan 11, thereby adjusting a heat dissipating efficiency of the heat dissipation device 10.

Referring to FIG. 5, a plot of the thermal resistance versus the fan speed of the heat dissipation device 10 is illustrated. When the processor 17 has a relatively low power, for example 35 watts (Qin=35 W), the thermal resistance of the heat dissipation device 10 decreases as the fan speed increases. When the processor 17 has a higher power, for example 40 and 45 watts (Qin=40 W, Qin=45 W), the thermal resistance of the heat dissipation device 10 first decreases and then increases, as the fan speed increases. Generally, the processor 17 has an operation power greater than 40 watts.

Referring to FIG. 6, the control system 16 is capable of adjusting the speed of the fan 11 and the operation power of the processor 17, according to temperatures respectively sensed by the three temperature sensors 133. The principle of fan speed and processor power adjustment of the heat dissipation device 10 is described in detail as follows.

First, the three temperature sensors 133 continuously sense temperatures S1, S2 and S3 of the respective positions where they sit. The control system 16 respectively compares the temperatures S1, S2 and S3 with a first critical temperature T1 which stands for a normal operating temperature of the processor 17.

In condition that the temperatures S1, S2 and S3 are all lower than or equal to the first critical temperature T1, the control system 16 keeps the operation power of the processor 17 unchanged. If the temperatures S1, S2 and S3 are all lower than or equal to the first critical temperature T1, it shows that heat dissipating efficiency of the heat dissipation device 10 satisfactorily meets the cooling needs of the processor 17. Accordingly, there is no need to adjust the operation power of the processor 17.

In condition, that anyone of the temperatures S1, S2, and S3 is higher than the first critical temperature T1, the control system 16 increases the speed of the fan 11. If anyone of the temperatures S1, S2, and S3 is higher than the first critical temperature T1, it shows that heat dissipating efficiency of the heat dissipation device 10 fails to meet the cooling needs of the processor 17. Accordingly, the speed of the fan 11 increases to improve the heat dissipating efficiency of the heat dissipation device 10. Successively, the control system 16 compares a difference between S1 and S2 with a first critical temperature difference N1, to check out whether there is a nonuniform temperature distribution caused by drying-out of the heat pipe 13. The first critical temperature difference N1 is defined with a value representing a threshold of normal temperature difference between two of the temperature sensors 133 on the heat pipe 13.

In condition that the difference between S1 and S2 is lower than or equal to the first critical temperature difference N1 (S1−S2<N1, or S1−S2=N1), the control system 16 keeps the operation power of the processor 17 unchanged. The condition S1−S2<N1 or S1−S2=N1 shows that there is no nonuniform temperature distribution on the heat pipe 13, and the heat dissipating efficiency can be finely improved by only increasing the speed of the fan 11. As such, there is no need to adjust the operation power of the processor 17.

In condition that the difference between S1 and S2 is larger than the first critical temperature difference N1 (S1−S2>N1), the control system 16 decreases the speed of the fan 11 and then compares the difference between S2 and S3 with a second critical temperature difference N2. The condition S1−S2>N1 shows that there is a nonuniform temperature distribution on the heat pipe 13, and the heat dissipating efficiency cannot be finely improved by increasing the speed of the fan 11. That is because the increased speed of the fan 11 leads to higher thermal resistance of the heat dissipation device 10. As such, the speed of the fan 11 is decreased to reduce the thermal resistance of the heat dissipation device 10, according to what is illustrated in FIG. 5. Then a difference between S2 and S3 is compared with second critical temperature difference N2 to further check whether there is a nonuniform temperature distribution on the heat pipe 13. The second critical temperature difference N2 is defined with a value representing another threshold of normal temperature difference between another two of the temperature sensors 133 on the heat pipe 13.

In condition that the difference between S2 and S3 is lower than or equal to the second critical temperature difference N2 (S2−S3<N2, or S2−S3=N2), the control system 16 keeps the operation power of the processor 17 unchanged. The condition S2−S3<N2 or S2−S3=N2 shows that the nonuniform temperature distribution on the heat pipe 13 is eliminated by decreasing the speed of the fan 11, and it is the drying-out condition of the heat pipe 13 which leads to former low heat dissipating efficiency. As such, the heat dissipating efficiency can be improved by only decreasing the speed of the fan 11 to achieve lower thermal resistance of the heat dissipation device 10.

In condition that the difference between S2 and S3 is larger than the second critical temperature difference N2 (S2−S3>N2), the control system 16 decreases the speed of the fan 11 and respectively compares the temperatures S1, S2 and S3 with a second critical temperature T2. The condition S2−S3>N2 shows that the thermal resistance of the heat dissipation device 10 has not been reduced to a minimum value by decreasing the speed of the fan 11, according to FIG. 5. As such, the speed of the fan 11 further decreases to achieve a lower thermal resistance of the heat dissipation device 10, and the temperatures S1, S2 and S3 with a second critical temperature T2 to check out whether the processor 17 has been cooled to a satisfied temperature lower than or equal to the second critical temperature T2.

In condition that the temperatures S1, S2, and S3 are all lower than or equal to the second critical temperature T2, the control system 16 keeps the operation power of the processor 17 unchanged. The condition that the temperatures S1, S2, and S3 are all lower than or equal to the second critical temperature T2 shows that, the processor 17 has been cooled to a satisfied temperature by further decreasing the speed of the fan 11. As such, there is no need to lower the operation power of the processor 17.

In condition, that anyone of the temperatures S1, S2, and S3 is higher than T2, the control system 16 decreases the operation power of the processor 17. The condition that the anyone of the temperatures S1, S2, and S3 is higher than T2 shows that, it is impossible to cool the processor 17 to the satisfied temperature range only by achieving lowest thermal resistance of the heat dissipation device 10. As such, the processor 17 can only be cooled by reducing the operation power thereof.

It is to be understood that the above-described embodiments are intended to illustrate rather than limit the disclosure. Variations may be made to the embodiments without departing from the spirit of the disclosure as claimed. The above-described embodiments illustrate the scope of the disclosure but do not restrict the scope of the disclosure.