LED lamp with improved heat sink

1. Field of the Invention

The present invention relates to a light emitting diode (LED) lamp, and more particularly to an LED lamp incorporating an improved heat sink which can effectively dissipate heat generated by the LED lamp, is compact and has a low cost.

2. Description of Related Art

As an energy-efficient light, an LED lamp has a trend of substituting the fluorescent lamp for indoor lighting purpose; in order to increase the overall lighting brightness, a plurality of LEDs are often incorporated into a signal lamp, in which how to efficiently dissipate heat generated by the LEDs becomes a challenge.

Some of the LED lamps directly utilize heat dissipating structures that are used for electronic components mounted in a computer, for example, CPUs, video graphic cards or hard disk drivers. A type of such heat sink which is called sunflower heat sink has a post-shaped conducting member and a plurality of fins extending outwardly and radially from a circumference of the conducting member. Such a sunflower heat sink is competent for dissipating heat generated by the electronic component mounted in the computer, since the electronic component is a single heat source. An end face of the conducting member has a surface area large enough to sufficiently contact the electronic component, whereby the heat generated by the electronic component can be instantly absorbed by the conducting member.

However, when such a sunflower heat sink is used in the LED lamp which has a plurality of LEDs and accordingly a plurality of heat sources, the end face of the conducting member can not sufficiently contact with the LEDs, whereby the heat generated by LEDs cannot be timely dissipated. To increase the diameter of the conducting member, the sunflower heat sink will become very bulky, which is unfavorable from the viewpoint of transportation and aesthetic appealing.

What is needed, therefore, is an LED lamp with an improved heat sink which can overcome the above-mentioned disadvantages.

An LED lamp includes a heat sink, an LED module attached to a top surface of the heat sink in a thermal conductive relationship therewith and a cover coupled to the top of the heat sink and covering the LED module. The heat sink is column-shaped and has a central axis. The heat sink comprises a conducting member and a plurality of spaced fins extending outwardly from the conducting member. A distance between each of inner edges of the fins and the central axis is gradually decreased from a top surface to a bottom surface of the heat sink. The fins are parallel to each other. Outer edges of the fins are coplanar with an outer circumference of the conducting member near the top surface of the heat sink.

Other advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an assembled, isometric view of an LED lamp in accordance with a preferred embodiment of the present invention;

FIG. 2 is an exploded view of FIG. 1 ;

FIG. 3 is a cross-sectional view of the heat sink taken along line III-III of FIG. 2 ;

FIG. 4 is a side elevation of the heat sink of FIG. 2 ; and

FIG. 5 is a bottom view of the heat sink of FIG. 2 .

Referring to FIGS. 1 and 2 , an LED lamp in accordance with a preferred embodiment of the present invention comprises a heat sink 10 , an LED module 20 thermally attached to a top surface of the heat sink 10 , a light reflector 30 mounted on the top surface of the heat sink 10 and surrounding the LED module 20 and a cover 40 enclosing the LED module 20 .

Referring to FIG. 3 to 5 , the heat sink 10 is integrally formed of a material with a good heat conductivity such as aluminum and copper and is column-shaped. The heat sink 10 is centrosymmetrical relative to a central axis thereof and comprises a conducting member 12 and a plurality of parallel fins 14 extending outwardly from the heat conducting member 12 . The conducting member 12 whose top surface is circular, has a strip-shaped bottom surface (shown in FIG. 5 ). Two opposite lateral sides of the conducting member 12 are curved surfaces and concaved toward the fins 14 , symmetrical to each other relative to an imaginary central plane of the heat sink 10 through the central axis thereof. Each lateral side is recessed from a circumference of the heat sink 10 (also an outer circumference of the conducting member 12 ) near a top of the heat sink 10 to a bottom of the heat sink 10 , and has a recessed depth gradually increased along a top-to-bottom direction of the heat sink 10 . Thus, a distance between inner edges of the fins 14 and the central axis is gradually decreased from the top to the bottom of the heat sink 10 . The heat sink 10 defines a tunnel 120 along the central axis thereof. The tunnel 120 is oval in cross section and symmetrical relative to the central plane of the heat sink 10 . The conducting member 12 has a round contacting portion 122 recessed downwardly from a central part of the top surface thereof. The LED module 20 is received in the top surface of the conducting member 12 and contacts with the round contacting portion 122 . The fins 14 extend outwardly from the two curved surfaces and are symmetrical to each other relative to the central plane of the heat sink 10 . The fins 14 are formed by using a milling tool cutting through the circumference and the bottom surface of the heat sink 10 to reach the lateral sides of the conducting member 12 , thereby define a plurality of parallel channels (not labeled) between every two neighboring fins 14 . Outer edges of the fins 14 are coplanar with the circumference of the heat sink 10 , which is coincident with the outer circumference of the conducting member 12 .

Particularly referring to FIG. 2 , the LED module 20 comprises an annular printed circuit board (not labeled) and a plurality of LEDs 22 mounted evenly on the printed circuit board. A circular through hole 24 is defined in a centre of the LED module 20 and has a size slightly large than that of the tunnel 120 of the heat sink 10 .

The light reflector 30 facing toward the cover 40 is substantially bowl-shaped and defines a circular opening 32 in a centre of a bottom thereof. The light reflector 30 has an engaging flange 34 extending inwardly and horizontally to surround the opening 32 . The engaging flange 34 is designed to be suitable for being coupled to the top surface of the heat sink 10 and surrounding the contacting portion 122 of the heat sink 10 on which the LED module 20 is mounted.

The cover 40 is globose and made of transparent plastic or glass. The cover 40 is formed with a receiving opening (not shown) at a bottom thereof. A fixing flange (not shown) extends inwardly and horizontally from the bottom of the cover 40 and surrounds the receiving opening. The fixing flange is coupled with the engaging flange 34 of the light reflector 30 when assembling the cover 40 to the LED lamp.

In assembly of the LED lamp, the LED module 20 is mounted on the contacting portion 122 of the heat sink 10 and secured via screws (not shown) or adhering. In order to enhance a thermal exchanging ability between the LED module 20 and the heat sink 10 , thermal grease is preferred to be filled between a bottom surface of the LED module 20 and the contacting portion 122 . The light reflector 30 is secured on the top surface of the heat sink 10 by the engaging flange 34 being coupled to the top surface of the heat sink 10 and surrounding the LED module 20 . The fixing flange of the cover 40 is fixed to the engaging flange 34 of the light reflector 30 ; thus, the cover 40 can securely cover the LED module 20 .

In use of the LED lamp, when the LED module 20 is activated to generate light, the LED module 20 generates a mass of heat which is simultaneously absorbed by the conducting member 12 of the heat sink 10 and then evenly delivered to the fins 14 to be dissipate into ambient air via the fins 14 , whereby the LED module 20 is cooled duly and timely, and the LEDs 22 can thus function normally. As the heat sink 10 is mainly formed by cutting a solid block with a column configuration, the heat sink 10 can be easily and economically formed.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.