Abstract: A fan has a fan, an impeller and a motor. The impeller is disposed in the fan frame, and the motor is disposed in the fan frame for driving the impeller. The fan frame has a housing, a base and at least one connecting element. The housing has an inlet and an outlet, and the base is disposed in the housing and at the outlet. The connecting element is disposed between the housing and the base. The base has a first airflow guiding structure disposed on the circumference of the base. The housing has a second airflow guiding structure disposed on the inner circumference thereof and adjacent to the outlet. The first airflow guiding structure and the second airflow guiding structure are correspondingly disposed.

Abstract: A fan includes a fan frame and an impeller. The fan frame includes a frame body and a base, and the impeller is accommodated in the main body and is disposed on the base. The frame body has a column-shaped passage, an airflow outlet and an airflow inlet. The main body further has two expansion portions respectively disposed adjacent to the outlet and inlet. The expansion portions extend from the column-shaped passage to the outlet and the inlet, respectively. The main body has at least two planar sides so as to allow parts of the expansion portions to respectively form straight-cut lines where the planar sides are located, respectively. The base has several straight-cut planes, and each of the straight-cut planes is located with respect to the straight-cut line.

Abstract: A serial fan of the present invention includes a first fan and a second fan, each of which includes a housing and an impeller disposed in the housing. The housings respectively include a plurality of connecting elements, and there are several air-guiding recesses defined on the connecting elements of the first fan or the second fan, which can guide air to smoothly flow out from the housing so as to increase airflow and air pressure and reduce noise.

Abstract: A fan of the present invention includes a fan housing and an impeller disposed in the fan housing. The fan housing includes a plurality of connecting elements at its air outlet. Each connecting element includes a plurality of air-guiding teeth thereon, which can guide the air to flow smoothly out from the fan housing so as to increase airflow and air pressure, and reduce the noise.

Abstract: A fan includes a fan frame and an impeller. The fan frame includes a frame body and a base, and the impeller is accommodated in the main body and is disposed on the base. The frame body has a column-shaped passage, an airflow outlet and an airflow inlet. The main body further has two expansion portions respectively disposed adjacent to the outlet and inlet. The expansion portions extend from the column-shaped passage to the outlet and the inlet, respectively. The main body has at least two planar sides so as to allow parts of the expansion portions to respectively form straight-cut lines where the planar sides are located, respectively. The base has several straight-cut planes, and each of the straight-cut planes is located with respect to the straight-cut line.

Abstract: A composite fan frame includes a first frame and a second frame. The first frame has a first surface formed with at least one first protrusion portion. The second frame has a second surface formed with at least one first recess portion. When the first surface touches the second surface, the first protrusion portion is inserted into the first recess portion along a predetermined sliding direction such that the first frame and the second frame are combined. Also, a composite fan having the composite fan frame is disclosed.

Abstract: A serial fan is provided and includes a first fan and a second fan. The first fan includes a first frame, and the second fan includes a second frame. The first frame and the second frame form a frame set. The first frame has at least one first locking portion. The second frame has at least one second locking portion disposed corresponding to the first locking portion. When the first fan and the second fan are assembled, the first locking portion inserts in the second locking portion along a rotational direction so that the first frame and the second frame are connected in series.

Abstract: An impeller used in a fan is provided. The impeller includes a hub and a plurality of blades disposed around the hub. The hub has at least one curve-shape surface. A fan comprises a fan frame, an impeller, and a motor. The impeller disposed in the fan frame comprises a hub and a plurality of blades disposed around the hub, wherein the hub has at least one curve-shape surface and an airflow guiding structure disposed on an outer circumference of the hub. The motor is disposed in the impeller for driving the impeller.

Abstract: A fan has a fan, an impeller and a motor. The impeller is disposed in the fan frame, and the motor is disposed in the fan frame for driving the impeller. The fan frame has a housing, a base and at least one connecting element. The housing has an inlet and an outlet, and the base is disposed in the housing and at the outlet. The connecting element is disposed between the housing and the base. The base has a first airflow guiding structure disposed on the circumference of the base. The housing has a second airflow guiding structure disposed on the inner circumference thereof and adjacent to the outlet. The first airflow guiding structure and the second airflow guiding structure are correspondingly disposed.

Abstract: A serial fan of the present invention includes a first fan and a second fan, each of which includes a housing and an impeller disposed in the housing. The housings respectively include a plurality of connecting elements, and there are several air-guiding recesses defined on the connecting elements of the first fan or the second fan, which can guide air to smoothly flow out from the housing so as to increase airflow and air pressure and reduce noise.

Abstract: A fan of the present invention includes a fan housing and an impeller disposed in the fan housing. The fan housing includes a plurality of connecting elements at its air outlet. Each connecting element includes a plurality of air-guiding teeth thereon, which can guide the air to flow smoothly out from the fan housing so as to increase airflow and air pressure, and reduce the noise.

Abstract: A composite fan frame includes a first frame and a second frame. The first frame has a first surface formed with at least one first protrusion portion. The second frame has a second surface formed with at least one first recess portion. When the first surface touches the second surface, the first protrusion portion is inserted into the first recess portion along a predetermined sliding direction such that the first frame and the second frame are combined. Also, a composite fan having the composite fan frame is disclosed.