Bi-directional fan cooling method for multi-axis controller

1. Field of the Invention

The present invention relates to electronic device cooling technology, and more particularly, to a cooling method for multi-axis controller.

2. Description of the Related Art

On the controller cooling technology for robots, US2006/0128261 discloses a cooling arrangement for a humanoid robot, which has a powered fan provided inside each air vent hole in a shell of a humanoid robot so that the cooling air can flow laterally across the inner space, and a uniform cooling effect can be achieved. However, to achieve the expected cooling effect, a certain amount of air vent holes and powered fans must be provided, increasing the cost. Further, U.S. Pat. No. 7,894,191 a fan rotation control method for controlling a rotation of each of a plurality of system cooling fans by: storing a supply cooling amount, calculating a necessary cooling amount, the supply cooling amount and the temperature of the operation unit, determining the fan rotation number and controlling the rotation of each system cooling fan. However, this approach is more suitable for use in stable heat sources. If the temperature of each heat source is not stable, this approach can lead to deterioration of the cooling efficiency

The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a cooling method for multi-axis controller, which is applicable to heat sources of uncertainty in temperature, enhancing the cooling efficiency.

To achieve this and other objects of the present invention, a cooling method for multi-axis controller comprises two steps. At first, enable a first temperature sensor and a second temperature sensor to respectively detect the temperature of a first heat source and the temperature of a second heat source and then to provide the respective detected data to a control unit for comparison with a predetermined upper temperature limit. Thereafter, enable the control unit to drive a first bi-directional fan adjacent to the first heat source to exhaust air and then return to the first step if the temperature of the first heat source is higher than the predetermined upper temperature limit, or, enable the control unit to drive a second bi-directional fan adjacent to the second heat source to exhaust air and then return to the first step if the temperature of the second heat source is higher than the predetermined upper temperature limit.

Preferably, enable the control unit to determine whether or not the absolute temperature difference value between the temperature of the first heat source and the temperature of the second heat source surpasses a predetermined temperature difference limit if the temperature of the first heat source and the temperature of the second heat source are below the predetermined upper temperature limit, and then return to the first step if the absolute temperature difference value between the temperature of the first heat source and the temperature of the second heat source is below the predetermined temperature difference limit. If the absolute temperature difference value between the temperature of the first heat source and the temperature of the second heat source surpasses the predetermined temperature difference limit and the temperature of the first heat source surpasses the temperature of the second heat source, enable the control unit to drive the first bi-directional fan to exhaust air and the second bi-directional fan to intake air and then return to the first step. If the absolute temperature difference value between the temperature of the first heat source and the temperature of the second heat source surpasses the predetermined temperature difference limit and the temperature of the first heat source is below the temperature of the second heat source, enable the control unit to drive the first bi-directional fan to intake air and the second bi-directional fan to exhaust air and then return to the first step.

Other advantages and features of the present invention will be fully understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference signs denote like components of structure.

FIG. 1 is a flow chart of a cooling method for multi-axis controller in accordance with the present invention.

FIG. 2 is a perspective view of a multi-axis controller using the cooling method of the present invention.

FIG. 3 is a schematic plain view of the multi-axis controller shown in FIG. 2 .

FIG. 4 is similar to FIG. 3 , illustrating the first bi-directional fans in the air intake mode and the second bi-directional fans in the exhaust mode.

FIG. 5 is similar to FIG. 3 , illustrating the first bi-directional fans and the second bi-directional fans in the exhaust mode.

FIG. 6 is similar to FIG. 3 , illustrating the first bi-directional fans in the exhaust mode and the second bi-directional fans in the air intake mode.

Referring to FIGS. 2 and 3 , a cooling method of the invention is adapted for use in a multi-axis controller 10 . The multi-axis controller 10 comprises, in structure, a housing 12 , a first heat source 14 mounted in the housing 12 , a first temperature sensor 16 fixedly mounted in the housing 12 adjacent to the first heat source 14 , two first bi-directional fans 18 facing toward the first heat source 14 , a second heat source 20 mounted in the housing 12 , a second temperature sensor 22 fixedly mounted in the housing 12 adjacent to the second heat source 20 , two second bi-directional fans 24 facing toward the second heat source 20 , and a control unit 26 electrically coupled with the first temperature sensor 16 , the second temperature sensor 22 , the first bi-directional fans 18 and the second bi-directional fans 24 . It is to be noted that the first bi-directional fans 18 and the second bi-directional fans 24 are respectively mounted in two opposite peripheral walls of the housing 12 ; the housing 12 has air vents 121 located one peripheral wall thereof between the first bi-directional fans 18 and the second bi-directional fans 24 . Referring to FIG. 1 again, the cooling method comprises the steps described as follows:

Step a): After the multi-axis controller 10 is started up, the control unit 26 controls the first bi-directional fans 18 and the second bi-directional fans 24 to work as air intake fans or exhaust fans as predetermined. In this embodiment, the first bi-directional fans 18 are controlled to work as air intake fans for drawing external cold air into the inside of the housing 12 and the second bi-directional fans 24 are controlled to work as exhaust fan for expelling internal hot air out of the housing 12 (see FIG. 4 ). Thereafter, the control unit 26 controls the first temperature sensor 16 and the second temperature sensor 22 to detect the temperature of the first heat source 14 and the temperature of the second heat source 20 and to feed back the detected temperature data for comparison with a predetermined upper temperature limit.

Step b): The control unit 26 determines, at first, whether or not the temperature of the first heat source 14 surpasses the predetermined upper temperature limit, and then controls the first bi-directional fans 18 to exhaust air if the temperature of the first heat source 14 surpasses the predetermined upper temperature limit (see FIG. 5 ), thereby generating convection to carry waste heat from the first heat source 14 . At this time, the second bi-directional fans 24 are maintained to exhaust air. Thereafter, return to step a) for enabling the control unit 26 to repeatedly determine whether or not the temperature of the first heat source 14 surpasses the predetermined upper temperature limit.

If the temperature of the first heat source 14 is below the predetermined upper temperature limit, the control unit 26 immediately determines whether or not the temperature of the second heat source 20 surpasses the predetermined upper temperature limit. If the temperature of the second heat source 20 surpasses the predetermined upper temperature limit at this time, the control unit 26 immediately controls the second bi-directional fans 24 to exhaust air (see FIG. 4 ). At this time, the first bi-directional fans 18 are maintained in the air intake mode, allowing generation of a convection to carry waste heat from the second heat source 20 . Thereafter, the control unit 26 returns to step a) for determining whether or not the temperature of the first heat source 14 surpasses the predetermined upper temperature limit.

Step c): If the temperature of the first heat source 14 and the temperature of the second heat source 20 are below the predetermined upper temperature limit, the control unit 26 immediately determines whether or not the absolute temperature difference value between the temperature of the first heat source 14 and the temperature of the second heat source 20 surpasses a predetermined temperature difference limit. If the absolute temperature difference value is below the predetermined temperature difference limit, the control unit 26 returns to step a) for determining whether or not the temperature of the first heat source 14 surpasses the predetermined upper temperature limit.

If the absolute temperature difference value between the temperature of the first heat source 14 and the temperature of the second heat source 20 surpasses the predetermined temperature difference limit, the control unit 26 subtracts the temperature of the second heat source 20 from the temperature of the first heat source 14 and then determines whether or not the remainder is larger than zero. If the remainder is larger than zero, it means that the temperature of the first heat source 14 is higher than the temperature of the second heat source 20 . At this time, the control unit 26 controls the first bi-directional fans 18 to exhaust air and the second bi-directional fans 24 to intake air (see FIG. 6 ), thereafter, the control unit 26 returns to step a) for determining whether or not the temperature of the first heat source 14 surpasses the predetermined upper temperature limit.

If the remainder obtained by subtracting the temperature of the second heat source 20 from the temperature of the first heat source 14 is smaller than zero, it means that the temperature of the second heat source 20 is higher than the temperature of the first heat source 14 . At this time, the control unit 26 controls the first bi-directional fans 18 to intake air and the second bi-directional fans 24 to exhaust air (see FIG. 4 ). If the absolute temperature difference value between the temperature of the first heat source 14 and the temperature of the second heat source 20 is below the predetermined temperature difference limit at this time, the control unit 26 immediately returns to step a) for determining whether or not the temperature of the first heat source 14 surpasses the predetermined upper temperature limit, and thus, one operating cycle is completed.

It can be seen by the steps described above that the cooling method of the invention enables multiple temperature sensors 16 , 22 to detect the temperatures of multiple heat sources 14 , 20 of uncertainty in temperature and then to provide the detected temperature data to a control unit 26 so that the control unit 26 can control respective bi-directional fans 18 , 24 to exhaust air or to intake air subject to an analysis on the detected temperature data, achieving enhanced cooling efficiency.