Complementary fan rotational speed control method and apparatus

A complementary fan rotational speed control method and apparatus for simultaneously monitoring the rotation speeds of two or more fans includes a control unit to output pulse width modulation (PWM) control power supply to activate operation of a first fan and a second fan. The first and the second fan deliver rotation pulse signals to the control unit. When the control unit detects the rotation speed of either the first or second fan decreases, it actuates other fan to increase rotation speed and issues a warning signal to secure cooling effect and increase the service life of the fans.

FIELD OF THE INVENTION

The present invention relates to a complementary fan rotational speed control method and apparatus, and particularly to a method and apparatus that uses a control unit to detect the rotation speed of two or more fans and to immediately increase the rotation speed of one fan when the rotation speed of other fan decreases thereby to secure cooling effect and increase the service life of the fans.

BACKGROUND OF THE INVENTION

At present, nearly all elements mounted on the circuit boards inside instruments, servers and power supplies have radiation apparatus installed thereon. Fan is one of the indispensable elements in these radiation apparatus. It can disperse thermal energy received by aluminum radiation fins or discharge thermal energy generated by the elements contained in the computers, servers and power supplies outside the casing so that the elements on the circuit boards may function properly without breaking down.

Thus heat dissipation mechanism has become an important procurement criterion of most 1U and 2U servers. The apparatus that adopt rack type structure employ a design different from general information products. They have a flat and narrow space, and electronic elements are densely located in a confined space. They have to overcome a high system resistance to smoothly discharge thermal energy. Hence airflow volume must be sufficiently large and the static pressure must be adequately strong to force and dispel the high temperature outside the machine casing.

Moreover, due to the servers often operate non-stop 24 hours a day, service life of the fans become very important. Once the fans malfunction, the high thermal energy of CPU, chip sets, power supply and memory could break down or burn out at high temperature. Thus the fans used in the servers not only have to withstand high temperature, they also should have durability warranty. Therefore some vendors have designed cooling fan with three essential criteria, i.e. high airflow, high static pressure and long service life.

While most fans used in the servers or power supply of servers have met the criteria mentioned above, in practical configuration the durability of the fans often is shortened. This mainly is caused by the design of heat dissipation arrangement. The fans usually are set to operate independently until they are broken down and replaced by new ones. Another design is to arrange many fans in the server and control in a fault-tolerant fashion. When one fan is down, another fan is activated immediately to carry on heat dissipation for the server to ensure that elements in the server can function properly. However such arrangement still cannot increase the durability of the fans. Moreover, when the rotation speed of malfunctioned fan drops and before other fan is activated, cooling effect cannot be maintained as desired.

SUMMARY OF THE INVENTION

Therefore the primary object of the invention is to resolve the aforesaid disadvantages and overcome the drawbacks of the prior art. The invention provides a control unit to simultaneously detect the rotation speeds of two fans. When the rotation speed of one fan decreases, the control unit immediately increases the rotation speed of other fan. Thus not only heat dissipation effect can be secured, service life of the fans can also be lengthened. Moreover, a warning notice may be issued to alert monitor which fan is malfunction so that repairs or replacement action may be taken promptly.

In order to achieve the foregoing object, the complementary fan rotational speed control method and apparatus of the invention aims at concurrently monitoring the rotational speeds of two or more fans. A control unit outputs a pulse wide modulation (PWM) control power supply to activate a first fan and a second fan. When the first fan and the second fan are activated, pulse signals of the rotational speed are generated by the first fan and the second fan and transferred back to the control unit. The control unit, based on the feedback rotation speed pulse signals, detects the rotational speeds of the first fan and the second fan. In the event that the rotation speed of either the first fan or the second fan decreases and has been detected by the control unit, the control unit orders other fan to increase the rotation speed and issues a warning signal to ensure that cooling effect is maintained properly and service life of the fans may increase.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer toFIG. 1, the complementary fan rotational speed control apparatus of the invention includes a control unit1, a first fan2and a second fan3connecting to the control unit1. The rotation speeds of the first fan1and the second fan2may be reduced to increase the service lives thereof, and provide sufficient cooling effect. In the event that the rotation speed of either one of the first or second fan1or2decreases, the rotation speed of other fan increases to maintain cooling effect for the elements which heat dissipation is required.

The control unit1outputs PWM control power supply11and12.

The first fan2may be an axial fan or a radial fan. It receives the PWM control power supply11output from the control unit1. After the first fan2is activated, it outputs a first rotation pulse signal21to the control unit1.

The second fan3may be an axial fan or a radial fan. It receives the PWM control power supply12output from the control unit1. After the second fan3is activated, it outputs a second rotation pulse signal31to the control unit1.

After the control unit1outputs the PWM control power supply111and12that are received by the first and the second fan2and3, the first and the second fan2and3are activated and rotate, and deliver the first rotation pulse signal21and second rotation pulse signal31to the control unit1. The control unit1detects the operational conditions of the first fan2and the second fan3. If the control unit1detects that the rotation speed of the first fan2decreases, it actuates the second fan3to increase its rotational speed to a full speed to maintain the cooling effect, and in the means time, issues a warning signal to alert operators to replace or repair the first fan2so that the service life of the fan may increase.

Refer toFIGS. 1,2A and2B for the control block diagram and process flow of the invention. As shown in the drawings, initially, power supply to the first fan2starts, and the rotation speed counter of the first fan2adds one, then determine whether the counter of the first fan2is subtracted by one and becomes zero; if no, the power supply for the second fan3is started;if yes, determine whether the rotation speed of the first fan2is too slow;if yes, close the counter value of the second fan3to become zero, and issue a malfunction warning signal;if no, determine the power supply close counter value of the second fan3based on the rotation speed counter value of the first fan2;then load the power supply close counter value of the first fan2, and activate the power supply of the second fan3, and add one to the rotation speed counter of the second fan3, and determine whether the counter of the second fan3is subtracted by one and becomes zero; if no, turn off the power supply of the first fan2;if yes, determine whether the rotation speed of the second fan3is too low; if yes, close the counter value of the first fan2to become zero, and issue a malfunction warning signal;if no, determine the power supply close counter value of the first fan2based on the rotation speed counter value of the second fan3; then load the power supply close counter value of the second fan3, and turn off the power supply of the first fan2, and determine whether the counter of the first fan2is subtracted by one and becomes zero;if no, turn off the power supply of the second fan3; if yes, load the power supply start counter value of the first fan2, and turn off the power supply of the second fan3;then determine whether the counter of the second fan3is subtracted by one and becomes zero; if no, turn on the power supply of the first fan2; if yes, load the power supply start counter value of the second fan3, and turn on the power supply of the first fan2. The processes are repeated under control. When the rotation speed of either the first fan2or the second fan3decreases, the rotation speed of other fan is increased to maintain the cooling effect for the elements which require heat dissipation. And a warning signal is issued to increase the service life of the fans.

Refer toFIG. 3for the invention in a use condition. A server4(a general personal computer) has a casing41which has a rear panel (or front panel)42. On the panel42, there are the first fan2and the second fan3installed thereon. When the first and the second fan2and3in operation, they can discharge heat generated by the elements located in the casing41of the server4outside the casing41so that the elements in the casing41may function properly.

In the event that the rotation speed of either the first fan2or the second fan3decreases, the rotation speed of other fan increases to maintain the cooling effect for the elements which require heat dissipation. And a warning signal is issued to increase the service life of the fans.

Refer toFIG. 4for the invention in another use condition. A power supply5has a casing51which has a rear panel (or front panel)52. On the panel52, there are the first fan2and the second fan3installed thereon. When the first and the second fan2and3in operation, they can discharge heat generated by the elements located in the casing51of the power supply5outside the casing51so that the elements in the casing51may function properly.

In the event that the rotation speed of either the first fan2or the second fan3decreases, the rotation speed of other fan increases to maintain the cooling effect for the elements which require heat dissipation. And a warning signal is issued to increase the service life of the fans.

While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are tended to cover all embodiments which do not depart from the spirit and scope of the invention.