Abstract: A centrifugal fan. A hub covers a driving device. An impeller surrounds the hub and includes a first blade set and a second blade set. The first blade set surrounds the hub and includes a first combining portion, a second combining portion, and a plurality of first blades. The first and second combining portions are respectively connected to the first blades. The second blade set includes a third combining portion, a fourth combining portion, and a plurality of second blades. The third and fourth combining portions are respectively connected to the second blades. The first blade set is assembled with the second blade set by assembling the first combining portion with the third combining portion and assembling the second combining portion with the fourth combining portion.

Abstract: A fan motor speed control circuit is disclosed. The circuit includes a digital/analog converting unit and a driving unit. The digital/analog converting unit takes charge of receiving a pulse width modulation (PWM) signal and converting it into a voltage signal. The driving unit is connected with the digital/analog converting unit in series for receiving the voltage signal, while the driving unit provides a first predetermined voltage level and a second predetermined voltage level as references. The fan motor is kept to run with a low constant rotation speed when the voltage signal level is higher than the first predetermined voltage level, with a full constant rotation speed when the voltage signal level is lower than the second predetermined voltage level, and with a variable rotation speed when the voltage signal level is lower than the first predetermined voltage level and higher than the second predetermined voltage level.

Abstract: A centrifugal fan, comprising a frame and a first guide portion. The frame comprises a bottom portion and a curved wall connected thereto. The curved wall comprises an airflow inlet. The first guide portion disposed along the curved wall at the bottom portion comprises a beginning area, a middle area, and an ending area. The middle area connects the beginning and the ending areas, and the beginning area extends from the airflow inlet. The beginning area has a width less than that of the ending area, and the beginning area has a height greater than that of the ending area.

Abstract: A stator structure includes a stator assembly and a protective body, and the stator assembly is covered by the protective body. Additionally, a manufacturing method of the stator structure, which includes the steps of providing a stator assembly, providing a mold, disposing the stator assembly in the mold, applying a filler into a space defined between the mold and the stator assembly, and removing the mold to form the stator structure with the protective body, is also disclosed.

Abstract: A heat dissipation system includes a fan module and a client device. The fan module includes at least two fans, each of which has a controller and a sensor. The client device is electrically connected to the controllers of the fans and generates a first control request and a second control request to allow the fans of the fan module to respectively operate in synchronous and asynchronous modes. The dissipation system allows the fans to be switched between these modes in accordance with the environment.

Abstract: A stator structure. A first stator part includes a first engaging portion. A second stator part includes a second engaging portion corresponding to the first engaging portion. The first and second stator parts are of the same material. When the first stator part is assembled with the second stator part, the first engaging portion is engaged with the second engaging portion so as to form the stator structure with a waist post.

Abstract: A fan includes a fan frame and an impeller. The fan frame has a housing, a base and at least one supporting element. The inner wall of the housing has at least one guiding portion for increasing an airflow intake of the fan, and the base is disposed within the housing and has a bottom portion and a pressurizing portion. The pressurizing portion is disposed around the bottom portion for increasing an air pressure of the fan. The supporting elements are connected to the housing and the pressurized portion of the base. The impeller is disposed within the housing and supported by the base.

Abstract: A passive heat-dissipating fan system comprises an air-providing device, a cold-end passive heat-dissipating assembly, a hot-end passive heat-dissipating assembly, a separation device capable of guiding airflow to the cold-end and hot-end passive heat-dissipating assemblies, and a cooling device which is disposed in the separation device and has cold and hot ends. When the airflow from the air-providing device passes through the separation device and cooling device, airflow from the air-providing device is separated and then partially directed to the cold-end passive heat-dissipating assembly and partially directed to the hot-end passive heat-dissipating assembly respectively, expelling the heated airflow to an exterior of an electronic system.

Abstract: A brushless DC motor and a stator thereof. The stator comprises an upper magnetic pole piece and a lower magnetic pole piece. The upper magnetic pole piece comprises a plurality of upper protruding portions extending toward the lower magnetic pole piece, and the lower magnetic pole piece comprises a plurality of lower protruding portions extending toward the upper magnetic pole piece. The upper protruding portions and the lower protruding portions are substantially spaced apart and alternately arranged. A positioning portion extending from a distal end of each upper protruding portion is located below the magnetic ring of the rotor, to increase the magnetic force therebetween. Alternatively, a positioning portion can be formed between the lower protruding portions of the lower magnetic pole piece and extended to the bottom of the rotor; thus, an axial attraction force can be generated to stabilize the rotor.

Abstract: A current control device for a fan motor includes a current sampling module, a signal generating module, a current detecting module and a current controlling module. The current sampling module samples an operating current of the fan motor to generate a sampled current signal. The operating current is controlled according to a driving signal. The signal generating module generates a threshold current signal. The current detecting module receives the sampled current signal and the threshold current signal and generates a motor protecting signal according to the sampled current signal and the threshold current signal. The current controlling module receives the motor protecting signal and stops generating or decreases the driving signal according to the motor protecting signal.

Abstract: A fan includes a fan housing and an impeller. The fan housing includes a frame, a base disposed in the frame, a plurality of stationary blades disposed between the frame and the base, and a plurality of airflow-guiding elements extending inward from the frame and toward the base. The airflow-guiding elements and the stationary blades are alternately arranged. The impeller is disposed in the fan housing.

Abstract: A fan housing and a fan have stationary blades for guiding airflow. Each stationary blade has at least one airflow-guiding element extending therefrom along the circumference of the fan. The side wall of the airflow-guiding element changes the direction of the airflow so that the airflow at the outlet is fully introduced toward the heat source. Furthermore, the airflow-guiding element regulates the airflow, restrains the turbulent flow at the outlet and on the curved surface of the stationary blade, decreases the noise arising from the turbulent flow, and prevents foreign matter from entering the fan housing so as to protect the inside elements thereof.

Abstract: A permanent magnet (PM) stepping motor includes a rotor structure and a stator. The rotor structure includes an axis, multipolar yoke stacks, and at least one spacer. Each of multipolar yoke stacks includes an N multipolar yoke, a permanent magnet and an S multipolar yoke combined as a hamburger-like structure, and each N pole of the N multipolar yoke and each S pole of the S multipolar yoke are alternately aligned. One of the spacer is sandwiched between each pair of the multipolar yoke stacks. The stator circumnavigates the axis and the multipolar yoke stacks, and provides a magnetic field for the multipolar yoke stacks to make the axis rotating. This PM stepping motor has the advantage of a minimized magnetic pole pitch and a high torque, which cannot be achieved in conventional stepping motors.

Abstract: A method of manufacturing a dynamic bearing comprises providing a bearing having a through hole. A photoresist is coated on an inner wall of the through hole. An ultraviolet lamp capable of inserting into the through hole is provided. A mask having patterns of pressure-generating grooves is attached to the surface of the ultraviolet lamp. The ultraviolet lamp is inserted into the through hole to perform an exposure process with the mask. The exposed portions of photoresist are developed to appear portions of the inner wall underneath. The appeared portions of the inner wall are etched to form grooves on the bearing, and finally, the photoresist remaining on the inner wall of the through hole is stripped.

Abstract: The invention provides a motor driving device including a converter receiving and converting a non-electrical power source, such as light, heat, mechanical or chemical energy, to a first electrical power, and a selector electrically connected between the converter and a motor, for receiving the first electrical power and a second electrical power from a power source, such as an electrical power generator, and outputting the first or second electrical power according to a rotation speed of the motor.

Abstract: A dynamic bearing manufacturing method including steps as follow. A plate is provided and a plurality of grooves is formed on a surface of the plate. The plate formed with grooves is rolled into a hollow cylinder. The grooves are located on the inner surface of the hollow cylinder, and thus to reduce cost of manufacturing process.

Abstract: A fan includes a frame and an impeller. The impeller is disposed in the frame and the impeller has a plurality of blades. Each blade has a wing part and a flap part, and the wing part and the flap part form a predetermined angle. A blade is also disclosed.

Abstract: A passive fan assembly includes an impeller and a plurality of guide blades disposed in front of the impeller. The impeller includes a plurality of blades extending at about 90 degrees relative to the guide blades. Thus, when airflow enters the passive fan assembly, the guide blades guide the airflow to effectively impact on blades of the impeller.

Abstract: This specification discloses a heat sink for coolers. The heat sink contains a heat conductive element, a heat dissipating shell covering over the heat conductive element, and a plurality of heat dissipating fins installed on the heat dissipating shell. The heat conductive element is comprised of a heat conductive plate and a heat conductive block installed at the center thereof. The area of the lower surface of the heat conductive block is greater than that of the upper surface thereof. When the lower surface of the heat conductive plate is in contact with a device that needs heat dissipation, the heat conductive block increases the heat conducting volume at the center of the heat conductive plate, so that the heat produced by the device can be released at an optimal rate.