BACKGROUND OF THE INVENTION
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1. Field of the Invention
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The present invention relates to a switch and a motor-cooling device for an electric fan, and more particularly to a switch for controlling ON/OFF of the power supply and adjusting the speed of an electric fan
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2. Description of the Prior Art
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The existing switches and cooling devices for an electric fan are divided into the following two types:
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1. One type is as shown in FIG. 5, a switch for an electric fan is disposed on a fan body (not shown) outside a housing 62, and a motor 61 is disposed inside the housing 62. In order to dissipate the heat generated by the motor 61 and prevent the electric fan from blowing out hot air after a long time use of the motor 61, the housing 62 is defined with plural air inlet holes 622 in a flat end surface 621 thereof. However, since the end surface 621 is too small, it is incapable of taking in as much cooling air as needed, resulting in low heat dissipation efficiency. In addition, since the switch is disposed on the fan body outside the housing 62, operating the switch is inconvenient and needs the user to bend his back.
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2. The other type is as shown in FIG. 6, a motor 71 for an electric fan is disposed in a housing 72, and a switch 73 is disposed at a distal end of a housing 72. The switch 73 is formed with a protruded arc-shaped end at the distal end of the housing 72. The housing 72 is defined with plural air inlet holes 721 around the outer periphery thereof. By such arrangements, the area of the housing 72 for sucking cool air is increased, the cool air behind the switch 73, however, cannot be sucked into the housing 72. Therefore, improvements are needed. In addition, the arrangement of the air inlet holes 721 greatly increases the total length of the assembly of the switch 73 and the housing 72, thus occupying much space.
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The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.
SUMMARY OF THE INVENTION
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The technical problems to be solved:
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The existing switches and motor-cooling devices for an electric fan have low heat dissipation efficiency due to the poor design of the air inlet holes which cannot take in a large amount of cool air.
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In order to solve the above technical problem, a switch and a motor-cooling device for an electric fan in accordance with the present invention comprise a motor, a housing, a controller and a knob. The motor is connected to plural fan blades. The housing has one end connected to the motor and an end cap and encloses the motor. The other end of the housing is defined with a concave portion. On the bottom of the concave portion are provided plural assembling portions. The concave portion is formed with an outward-enlarged arc-shaped guiding surface around the periphery thereof and interiorly defined with plural inlet holes. The controller is assembled to the assembling portions in the concave portion and further provided with an assembling rod. The knob and the controller constitute the switch of the present invention. The knob is interiorly defined with an assembling hole to be assembled to the assembling rod and exteriorly formed with a tapered arc-shaped guiding surface.
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The present invention has the following advantages:
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The housing is defined with the concave portion in the one end thereof, and the concave portion is formed with the outward-enlarged arc-shaped guiding surface on the periphery thereof and interiorly defined with the plural inlet holes, so the cool air within the angular scope of the outward-enlarged circular guiding surface can be completely sucked into the housing. In addition, although the concave portion is centrally provided with the knob, the knob is formed with the guiding surface to guide the air behind the knob to be sucked into the concave portion. Therefore, the amount of the air for cooling the motor is greatly increased, and the present invention can obtain the optimal heat dissipation efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
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FIG. 1 is a perspective view of a switch and a motor-cooling device for an electric fan in accordance with the present invention;
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FIG. 2 is an exploded view of the switch and the motor-cooling device for an electric fan in accordance with the present invention;
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FIG. 3 is a cross-sectional view of the switch and the motor-cooling device for an electric fan in accordance with the present invention;
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FIG. 4 is a cross-sectional view illustrating how the air is sucked into the concave portion of the housing of the present invention;
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FIG. 5 is a cross-sectional view of a conventional switch and a conventional motor-cooling device for an electric fan; and
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FIG. 6 is a cross-sectional view of another conventional switch and another conventional motor-cooling device for an electric fan.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
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The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention.
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Referring to FIGS. 1-3, a switch and a motor-cooling device for an electric fan in accordance with the present invention comprise a motor 10, a housing 20, a controller 30, and a knob 40.
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The motor 10 is connected to plural fan blades 11.
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The housing 20 has one end connected to the motor 10 and an end cap 100 and encloses the motor 10. The other end of the housing 20 is defined with a concave portion 21. On a bottom of the concave portion 21 are provided plural assembling portions 22. The concave portion 21 is formed with an outward-enlarged arc-shaped guiding surface 23 around a periphery thereof. The concave portion 21 is further interiorly defined with plural inlet holes 24. The housing 20 is further defined with plural air outlet holes 25 in the other end thereof below the concave portion 21, as shown in FIG. 2.
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The controller 30 controls the speed and ON/OFF of the motor 10 and is assembled to the assembling portions 22 in the concave portion 21. The controller 30 is provided at both sides thereof with assembling portions 31 to be assembled to the assembling portions 22 by screw. The controller 30 is further provided with an assembling rod 32.
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The knob 40 and the controller 30 constitute the switch of the electric fan of the present invention. The knob 40 is interiorly defined with an assembling hole 41 in a surface thereof which is located opposite the controller 30 in such a manner that the assembling hole 41 is assembled to the assembling rod 32. The knob 40 is exteriorly formed with a tapered arc-shaped guiding surface 42. The guiding surface 42 is provided with plural anti-slip portions 43 around a periphery thereof.
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As shown in FIG. 4, with the above structure, when the electric fan is turned on to make the motor 10 drive the fan blades 11, the air will be sucked into the concave portion 21 of the housing 20 and then enter the housing 20 to absorb the heat of the motor 10 to cool the motor 10. The air which has absorbed the heat of the motor 10 will be discharged though the air outlet holes 25. By such arrangements, the present invention has the following advantages: when being sucked into the concave portion 21 of the housing 20, the air will move along the outward-enlarged arc-shaped guiding surface 23 of the concave portion 21. The air within the angular scope of the outward-enlarged arc-shaped guiding surface 23 will be completely sucked into the concave portion 21, and even the air behind the knob 40 can also be sucked into the concave portion 21 by cooperating with the guiding surface 42. Therefore, the amount of the air for cooling the motor 10 is greatly increased. In addition, the air which has absorbed the heat of the motor 10 can be smoothly discharged from the air outlet holes 25. Therefore, the motor 10 can obtain the optimal heat dissipation efficiency.
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While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
