Abstract:
A light emitting diode (LED) lamp includes a hollow connector, an LED module mounted on the connector, and a fin unit received in the connector. The connector has an inlet and an outlet couple to the inlet. Heat generated from the LED module is transferred to the connector to dissipate. The fan unit includes a first fan and a second fan rotating along contrary directions.

Description:
FIELD 
       [0001]    The disclosure generally relates to light emitting diode (LED) lamps, and more particularly to an LED lamp having good heat dissipation efficiency. 
       BACKGROUND 
       [0002]    LEDs have many beneficial characteristics, including low electrical power consumption, low heat generation, long lifetime, small volume, good impact resistance, fast response and excellent stability. These characteristics have enabled the LEDs to be widely used as a light source in electrical appliances and electronic devices. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a cross-sectional view of an LED lamp according to an exemplary embodiment of the present disclosure. 
           [0004]      FIG. 2  is a top view of the LED lamp of  FIG. 1 , wherein an envelope of the LED lamp is removed for clarity. 
       
    
    
     DETAILED DESCRIPTION 
       [0005]    An embodiment of an LED lamp in accordance with the present disclosure will now be described in detail below and with reference to the drawings. 
         [0006]    Referring to  FIGS. 1-2 , an LED lamp in accordance with an exemplary embodiment of the disclosure includes a connecting member  10 , an LED module  30  received in the connecting member  10 , a fan unit  20  received in the connecting member  10 , an envelope  50  mounted on the connecting member  10  and covering the LED module  30 , and a heat sink  70  mounted on the connecting member  10  and directly contacting the LED module  30 . 
         [0007]    The connecting member  10  can be opaque and is used to electrically connect a power source (not shown). The connecting member  10  includes a holder  11  and a connector  13 . 
         [0008]    A vertical cross section of the holder  11  is rectangular. The holder  11  is configured for screwing to a socket (not shown) to electrically connect the power source. A metallic patch is formed on an outside of a bottom end of the holder  11 . The metallic patch functions as a first electrode  111  of the LED lamp. A threaded periphery (not labeled) of the holder  11  functions as a second electrode  113  of the LED lamp to electrically connect the power source to drive the LED module  30  to lighten. The holder  11  is a standard element, so the LED lamp can be directly connect to a standard socket matching with the standard holder  11  to electrically connect with the power source. Thus, the LED lamp of the present disclosure can replace the traditional incandescent bulb and compact fluorescent bulb. 
         [0009]    The connector  13  and the holder  11  are made of a single piece. The connector  13  extends upwardly from a top end of the holder  11 . A vertical cross section of the connector  13  is trapezoidal and a width thereof is increased from a bottom end connecting the holder  11  to a top end away from the holder  11 . The connector  13  is a hollow tube with the top end and the bottom end being closed. A central portion of the top end of the connector  13  is recessed to define a housing  130  to receive the heat sink  70  and the LED module  30  therein. An inner surface of the connector  13  defines an inner space therein. The inner space is divided into a temperature controlled chamber  131  and a receiving chamber  133  along a height direction of the LED lamp. The temperature controlled chamber  131  communicates with the receiving chamber  133  and is located at top of the connector  13 . A temperature detector  135  is received in the temperature controlled chamber  131  and is fixed to a top of the temperature controlled chamber  131 . The temperature detector  135  detects a temperature of the temperature controlled chamber  131 . At least an inlet  136  is defined in a periphery of the top end of the connector  13 . The inlet  136  communicates the temperature controlled chamber  131 . An outlet  1331  is defined in a periphery of the bottom end of the connector  13 . The outlet  1331  communicates the receiving chamber  133 . A bore diameter of the receiving chamber  133  increases from a top portion connecting to the temperature controlled chamber  131  to a bottom portion away from the temperature controlled chamber  131 . 
         [0010]    The fan unit  20  includes a first fan  21  and a second fan  23 . Each of the first fan  21  and the second fan  23  is a centrifugal fan. The first fan  21  is received in a joint of the temperature controlled chamber  131  and the receiving chamber  133 . The first fan  21  rotates along a first direction. The second fan  23  faces and is spaced apart from the first fan  21 . The second fan  23  is received in the receiving chamber  133  and connects with the first fan  21  via a bearing  25 . The second fan  23  rotates in a second direction opposite to the first direction. The first fan  21  and the second fan  23  are controlled by different circuits which connect the temperature detector  135  and control the first fan  21  and the second fan  23  respectively or simultaneously according to different inputs received from the temperature detector  135 . 
         [0011]    The heat sink  70  is made of material having good heat conductive efficiency. The heat sink  70  absorbs heat of the LED module  30  and transfers the heat out of the connector  13  to dissipate. The heat sink  70  can be a vapor chamber, or a metallic plate and so on. A through hole  71  is defined in the heat sink  70 . 
         [0012]    Referring also to  FIG. 2 , the LED module  30  includes a print circuit board (PCB)  31  mounted on the heat sink  70  and a plurality of LEDs  33  arranged on the PCB  31 . A size of the PCB  31  is equal to or smaller than that of the heat sink  70  to ensure an entirely bottom surface of the PCB  31  be mounted on a top surface of the heat sink  70 . A through hole  313  is defined in a central portion of the PCB  31 . A bore diameter of the through hole  313  is equal to the through hole  71  of the heat sink  70 . The through hole  313  is aligned with and communicates with the through hole  71 . A sum height of the heat sink  70  and the LED module  30  is less than a depth of the housing  130 . 
         [0013]    The envelope  50  is hemispherical and a bottom end thereof is mounted on the top end of the connector  13 . A hollow tube  53  penetrates the envelope  50 , the through holes  313 ,  71  and the top end of the connector  13  to define a passage  51  therein to allow cool air flow through the connecting member  10  from the passage  51 . The hollow tube  53  and the envelope  50  can be made of a single piece. 
         [0014]    During the operation of the LED lamp, the LEDs  33  emit light and generate heat. Part of the heat is absorbed by the heat sink  70  and transferred to the connecting member  10  where it is dissipated. Simultaneously, the temperature detector  135  detects the temperature of the temperature controlled chamber  131 . When the temperature of the temperature controlled chamber  131  is lower than a predetermined temperature, only the first fan  21  is controlled to rotate in response to the input received from the temperature detector  135 . In this state, the first fan  21  guides cool air flowing through the passage  51 , the inlet  136  and into the temperature controlled chamber  131 . The heat of the heat sink  70  and the connecting member  10  is further dissipated by the cool air. After the cool air absorbing the heat, the heated air is exhausted the connector  13  from the outlet  1331 . When the temperature of the temperature controlled chamber  131  is larger than the predetermined temperature, both the first fan  21  and the second fan  23  are controlled to rotate in response to the input received from the temperature detector  135  to make the cool air flow through the connector  13  more quickly. Thus, the temperature of the LED lamp can be well controlled. 
         [0015]    In this embodiment, the first fan  21  and the second fan  23  are received in the connector  13  and rotate in opposite directions, so that cool air guided by the first fan  21  and the second fan  23  flows through the LED lamp more quickly than a conventional LED lamp having a fan mounted on an outer side thereof. Thus, the heat of the LED lamp is dissipated quickly and the LED lamp has stable performance. 
         [0016]    In this embodiment, the temperature detector  135  generating different inputs to control only the first fan  21  or both the first fan  21  and the second fan  23  simultaneously operating is environmentally friendly and energy efficient. Further, when the first fan  21  and the second fan  23  rotate with a high speed and in opposite directions, a heat dissipation efficiency of the LED lamp is improved 6-16% relative to two fans rotating in the same direction. 
         [0017]    It is to be further understood that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, 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 disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.