Fan module and control device thereof

The invention relates to a fan module, and more specifically to a control device providing fan speed modulation according to the number of loads, and a fan module with the control device.

With improvements in technology, the number of electronic components inside electronic devices has increased, and the generated heat during operation is also increased corresponding to the number of electronic components. To maintain performance, fans are conventionally used to dissipate heat therefrom. However, because the size of the housings of the electronic devices and the number of components therein are different, and heat generated in middle-sized and big-sized electronic devices is high, at least two fans are often used so as to achieve the effect of heat dissipation. Conventionally, a fan module comprises an integrated plurality of fans in a frame and is controlled by a control device.

Electronic devices with differing load numbers require fan modules having different powers. Conventional fan modules utilize fully powered and power-saving operating modes. Electronic devices with fewer loads require only the former mode while those with more loads require both modes. As shown in FIG. 1 , an electronic device 1 includes a fully powered fan module 2 , a power-saving fan module 3 , and a plurality of hot-plug loads 4 . With fewer loads 4 , the power-saving fan module 3 can dissipate heat. With increased loads 4 , the fully powered fan module 2 will start for heat dissipation.

Further, with temperature detection components built into fan modules 2 and 3 , control devices therein generate a control signal corresponding detected temperature variations and transmit the control signal to a plurality of fans. FIGS. 2A and 2B show relationships between temperature and speed with respect to the fan modules 2 and 3 . As shown in FIG. 2A , the relationship between the speed and temperature is linear, that is, with increased temperature (t 1 to t 2 ), the speed of the fans is increased accordingly (r 1 to r 2 ). However, in practice, the relationship between the temperature and speed may not be as direct. With the impact of noise, the line may become a curve, thereby degrading the performance of the control devices. Moreover, as shown in FIG. 2B , when the temperature exceeds the threshold temperature t 3 , the speed of the fans is increased to speed r 2 from speed r 1 . However, such rapid speed changes can reduce the life of electronic devices with more loads.

With concentration of components inside electronic devices and reduced size thereof, the amount of heat generated thereof increases. Thus, it is necessary to obtain a fan module with better heat dissipation performance and a control method thereof is called for.

The invention is directed to a control device having several operating modes and a fan module including the control device for electronic devices having differing numbers of loads.

A fan module and a control device thereof are provided. An exemplary embodiment of a fan module according to the present invention includes a plurality of fans and a control device. The control device includes a temperature sensing circuit and a driving circuit. The temperature sensing circuit detects an ambient temperature of the fans and generates a sensing signal to the driving circuit. The driving circuit is coupled between the fans and the temperature sensing circuit, and can drive the fans in a fully powered operating mode or a power-saving operating mode. The driving circuit can selects different operating modes in accordance with the sensing signal from the temperature sensing circuit to control the speed of the fans. The driving circuit drives the fans in the power-saving operating mode when the number of loads in the electronic device is stable, and drives the fans in the fully powered operating mode when the number of loads in the electronic device is unstable.

The control device further includes a switch coupled to the driving circuit in order to control the driving circuit in the fully powered or the power-saving operating modes. The switch provides manual control of operating modes of the driving circuit.

Moreover, the control device further includes an address setting device coupled between the driving circuit and the fans, enabling the driving circuit to directly retrieve the operating condition of each fan. The number and position of malfunctioning fans can also be obtained.

The invention will be described by way of exemplary embodiments, but not limitations, illustrated in the accompanying drawings in which like references denote similar elements, and in which:

FIG. 1 is a schematic diagram of a conventional electronic device having two different fan modules and a plurality of loads.

FIG. 2A shows a fan speed to ambient temperature characteristic curve of a conventional fan module.

FIG. 2B shows a fan speed to ambient temperature characteristic curve of another conventional fan module.

FIG. 3 is a schematic diagram of an embodiment of a fan module of the invention.

FIG. 4 shows a fan speed to ambient temperature characteristic curve of an embodiment of a fan module in a power-saving operating mode.

FIG. 5 shows a fan speed to ambient temperature characteristic curve of another embodiment of a fan module in a fully powered operating mode.

FIG. 6 is a schematic diagram of another embodiment of a fan module of the invention.

As shown in FIG. 3 , a fan module 5 according to one embodiment of the invention comprises a plurality of fans 10 and a control device 20 . The control device 20 is coupled to the fans 10 and controls the fans at different ambient temperatures.

The fans can be integrated in a frame (not shown), and a signal line and a power line of each fan 10 are coupled to the control device 20 .

The control device 20 includes a temperature sensing circuit 21 , a driving circuit 22 , and a switch 23 .

The temperature sensing circuit 21 includes at least a thermal sensor (not shown), for example, a thermistor. The temperature sensing circuit 21 detects the ambient temperature of the fans 10 and generates a sensing signal S temp according to the detected ambient temperature.

The driving circuit 22 is coupled between the fans 10 and the temperature sensing circuit 21 , and includes at least a driving processor (not shown). A driver program for fully powered and power-saving operating modes is stored in the driving processor. The driving processor selects fully powered or power-saving operating modes in accordance with the sensing signal S temp transmitted from the temperature sensing circuit 21 , and then generates a fan driving signal S drive to control the fans in different operating modes. The fan driving signal S drive is a Pulse Width Modulation (PWM) signal.

The switch 23 , preferably can be manually operated, is coupled to the driving circuit 22 . The driving circuit 22 receives a high level signal when the switch 23 is open and a low level signal when the switch 23 is closed. In the embodiment, the driving circuit 22 receives a high level signal to operate the fans in fully powered operating mode, and receives a low level signal to operate the fans in power-saving operating mode.

In the embodiment, the control device 20 further includes an alarm device 24 coupled between the fans 10 and driving circuit 22 . The alarm device 24 transmits an alarm signal S alarm to the driving circuit 22 in response to failure of the fans 10 , thereby allowing the driving circuit 22 to modulate the fan driving signal S drive according to the alarm signal S alarm . For example, if there are ten fans 10 in the fan module and two of the fans 10 are failed, the driving circuit 22 will control the other eight fans 10 in the fully powered operating mode and increases speed thereof, thereby compensating heat-removal degradation stemming from the two malfunctioned fans 10 .

With reference to FIG. 4 , when the driving circuit 22 is operated in the fully powered operating mode, the driving processor controls the speed of fans 10 in accordance with the sensing signal S temp . As shown in FIG. 4 , when the ambient temperature of the fans 10 is lower than temperature t 4 , the driving circuit 22 controls the fans 10 at speed r 3 , and increases the speed of the fans 10 to speed r 4 when the ambient temperature increases to temperature t 5 . If the ambient temperature continues to increase to temperature t 7 , the speed of the fans will be increased to speed r 5 , and if the ambient temperature decreases to temperature t 4 due to the acceleration of the fans 10 , the speed of the fans 10 will be decreased to speed r 3 . Further, if the ambient temperature does not decrease due to the acceleration of the fans 10 , the speed of the fans will be increased to speeds r 5 and r 6 when the ambient temperature exceeds temperatures t 7 and t 9 , respectively. If the ambient temperature decreases to temperatures t 6 and t 8 , the speed of fans 10 will be decreased to speeds r 4 and r 5 respectively. It is obvious that there are several nodes set in the temperature to speed characteristic curve, thus the speed of the fans 10 can be varied according to corresponding node. Control device 20 controls the speed of the fans 10 better, especially when applied in electronic devices whose number of hot-swap loads changes frequently.

With reference to FIG. 5 , when the driving circuit 22 is operated in the power-saving operating mode, the driving processor controls the speed of fans 10 in accordance with the sensing signal S temp . When the ambient temperature of the fans 10 exceeds temperature t 11 , the speed of the fans 10 is increased to speed r 8 from speed r 7 . If the ambient temperature continues to increase, the speed of the fans 10 is maintained at speed r 8 . However, if the ambient temperature decreases to temperature t 10 due to the acceleration of the fans 10 , the speed of the fans 10 is decreased to speed r 7 accordingly. It is obvious that with such two-stage temperature-speed control in the power-saving operating mode, the embodiment is suitable for electronic devices with fewer loads or having stable load number.

FIG. 6 shows another embodiment of the control device 20 of the invention. The control device shown in FIG. 6 further comprises an address setting device 25 coupled between the driving circuit 22 and the fans 10 . The address setting device 25 sets an address for each fan 10 . Moreover, the address setting device amplifies and transforms the fan driving signal S drive generated by the driving circuit 22 to several independent fan driving signals S drive . Thus, the driving circuit 22 is able to retrieve the operating condition of the fans 10 via the address setting device 25 in the event of any failure in the fans 10 , and then increase the speed of other fans 10 to compensate. The address setting device 25 further includes a plurality of indicators (not shown) according to the number of addresses, wherein a corresponding indicator turns on in the event of a failure of any of the fans 10 . Thus, users obtain the number and position of the malfunctioned fans easily

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.