This application claims priority of Chinese Application No. 201110058892.7, filed on Mar. 9, 2011.
1. Field of the Invention
This invention relates to a luminaire, and more particularly to a luminaire having an inner flow path.
2. Description of the Related Art
Referring to
As such, the heat-dissipating fins 92 are designed solely for increasing heat exchange area, and but not for enhancing airflow occurring during heat exchange. For example, a space defined between any two adjacent heat-dissipating fins 92 is closed at a bottom end of the base 90, so as not to have a sufficient contribution to heat exchange, thereby resulting in a limited cooling efficiency.
The object of this invention is to provide a luminaire that has an inner flow path arranged to allow air to flow into the luminaire to thereby carry heat away from a light-emitting unit for promoting the cooling efficiency.
Accordingly, a luminaire of this invention includes a base, a light-emitting unit, and a lamp cover.
The base includes a first tube part, a second tube part, a joint part connected between the first and second tube parts, a connector, and an inner flow path that is defined cooperatively by the first tube part, the joint part, and the second tube part in a coaxial manner and that has opposite first and second ends. The connector is disposed at the first end of the inner flow path, and is formed with at least one first aperture.
The light-emitting unit is disposed on the base in such a manner to allow heat generated from the light-emitting unit to be transmitted onto the base.
The lamp cover is fixed on the base for covering the light-emitting unit, and is formed with at least one second aperture.
When a temperature of the base is increased as a result of the heat, heat exchange occurs between the base and air in the inner flow path to form hot air in the inner flow path, so that the hot air flows out of the luminaire through one of the first and second apertures, and cold air is sucked into the luminaire through the other one of the first and second apertures, thereby creating an inner airflow.
Due to formation of the inner airflow and reduction of the inner flow path, the flow rate of the inner airflow is increased to enhance thermal convection.
These and other features and advantages of this invention will become apparent in the following detailed description of three preferred embodiments of this invention, with reference to the accompanying drawings, in which:
Before the present invention is described in greater detail in connection with the preferred embodiments, it should be noted that similar elements and structures are designated by like reference numerals throughout the entire disclosure.
Referring to
The base 2 includes a first tube part 21 formed from a thermal conducting material by die casting, a second tube part 22 having an inner diameter smaller than that of the first tube part 21, a joint part 23 connected between the first and second tube parts 21, 22, an extending part 24 connected to an end of the second tube part 22 distal from the joint part 23, a plurality of inner fins 25 extending from an inner surface of the second, tube part 22, and a plurality of elongated outer fins 26. The extending part 24 has a connecting end in fluid communication with the second tube part 22, and has an open end that is open toward a distal end of the lamp cover 4 (i.e., an end of the lamp cover 4 distal from the base 2). The extending part 24 has a slope increasing from the connecting end to the open end, so that air can be contracted into the second tube part 22. The outer fins 26 are disposed on the outer surfaces of the extending part 24, the second tube part 22, the joint part 23, and the first tube part 21.
The first tube part 21, the joint part 23, the second tube part 22, and the extending part 24 are coaxial with each other, and define cooperatively an inner flow path 101. The cross-sectional area ratio of the first tube part 21 to the second tube part 22 is greater than 2.25. The joint part 23 is frustoconical and can be a converging tube connected integrally between the first tube part 21 and the second tube part 22. In this embodiment, ratio of the maximum inner diameter to the depth of the extending part 24 is between 1.3 and 1.9. Such a ratio can result in a concentrated and smooth airflow. The functions of the inner flow path 101 and the convergent-divergent structure will be described hereinafter.
In this embodiment, the outer fins 26 are divided into four sets that are radially arranged with respect to the inner flow path 101. Each of the sets includes three outer fins 26. Any two adjacent sets form an angle of about 90 degrees therebetween. Each set of outer fins 26 are parallel to each other. However, the set number of the outer fins 26 and the fin number of each set may be changed according to arrangement of the light-emitting unit 3 without adverse influence on emission of light. Outer sides of the outer fins 26 have a streamline shape to facilitate smooth flow of air therearound to promote the heat-exchanging efficiency.
All of the first tube part 21, the second tube part 22, the joint part 23, the extending part 24, the inner fins 25, and the outer fins 26 are formed as a one-piece member. The base 2 further includes a connector 27 mounted removably to an end of the first tube part 21 distal from the joint part 23 and defining a first end 102 of the inner flow path 101. The connector 27 includes a ring plate 271, plurality of spaced-apart first apertures 270 formed through the ring plate 271, and a first annular wall 272 extending from an inner periphery of the ring plate 271 in a direction away from the first tube part 271. Alternatively, the connector 27 may be connected integrally to the first tube part 21.
The light-emitting unit 3 is disposed on an outer surface of the base 2 such that heat generated from the light-emitting unit 3 can be transmitted onto the base 2. In this embodiment, the light-emitting unit 3 includes a plurality of circuit boards 31 disposed on outer surfaces of the second tube part 22, the joint part 23, and the extending part 24, a plurality of LEDs 32 disposed on the circuit boards 31, and a driver 33 received within the first tube part 21 of the base 2. The driver 33 is electrically connected to the circuit boards 31 and the lamp cap 5. The lamp cap 5 is used to connect with an external power supply. To mount the driver 33, the first annular wall 272 of the connector 27 is sleeved on the lamp cap 5, in such a manner that the lamp cap 5 is disposed, under the connector 27. Next, a portion of the driver 33 is inserted downwardly into the first annular wall 272 of the connector 27, so that it is supported by the lamp cap 5. Afterwards, an insulation paste 6 is poured into spaces among the lamp cap 5, the first annular wall 272 of the connector 27, and the driver 33, so as to protect and fix the driver 33 relative to the lamp cap 5 and the connector 27. Finally, the remaining portion of the driver 33 is inserted into the first tube part 21 until the ring plate 271 comes into contact with the end of the first tube part 21 defining the first end 102 of the inner flow path 101. The first apertures 270 in the connector 27 are not sealed by the insulation paste 6.
With particular reference to
The lamp cover 4 covers the light-emitting unit 3, and includes a cover plate 41 for covering the open end of the extending part 24, and a plurality of transparent shade bodies 42 each adhered to two adjacent sets of the outer fins 26. Each of the shade bodies 42 is secured to the cover plate 41 at one end thereof, and to the outer surface of the first tube part 21 or the connector 27 at the other end thereof. The cover plate 41 is formed, with a plurality of second apertures 410. The cover plate 41 and the shade bodies 42 are formed from a transparent material by injection molding or stretch forming.
The function of the inner flow path 101 will now be described. With particular reference to
In a situation where the lamp cap 5 is disposed at the upper end of the luminaire 1, the inner flow path 101 is shown by the arrows in
When the luminaire 1 is used in another state where the lamp cap 5 is disposed at the lower end of the luminaire 1, hot air flows upwardly out via the second apertures 410 in the lamp cover 4, and cold air flows into the luminaire 1 via the first apertures 270 in the ring plate 271 of the base 2, subsequently over the driver 33 and the inner fins 25, and out of the luminaire 1 via the second apertures 410.
As such, the circuit boards 31 are disposed on only the outer surfaces of the second tube part 22 and the joint part 23. Hence, the LEDs 32 are disposed on the circuit hoards 31 attached to the second tube part 22 and the joint part 23, so that some of the LEDs 32 emit light toward the distal end of the lamp cover 4, and each of the remaining LEDs 32 emits light in a radial direction of the second tube part 22. In this embodiment, the shapes of the shade bodies 42 are designed to compensate for light emitted away from the distal end of the lamp cover 4.
Another difference between this embodiment and the first preferred embodiment is that, the connector 27 of the base 2 further includes a second annular wall 273 extending from the inner periphery of the ring plate 271 toward the first tube part 21. To mount the driver 33, the first annular wall 272 of the connector 27 is sleeved on the lamp cap 5, in such a manner that the lamp cap 5 is disposed under the connector 27. Next, the whole driver 33 is inserted downwardly into the first and second annular walls 272, 273 of the connector 27, so that it is supported by the lamp cap 5. Afterwards, an insulation paste 6 is poured into spaces among the lamp cap 5, the first and second annular walls 272, 273 of the connector 27, and the driver 33, so as to protect and fix the driver 33 relative to the lamp cap 5 and the connector 27. Finally, the second annular wall 273 of the connector 27 is inserted into the first tube part 21 until the ring plate 271 comes into contact with the end of the first tube part 21 defining apertures 270 in the connector 27 are not sealed by the insulation paste 6. In this embodiment, the connector 27 has a larger space for fixing and protecting the driver 33.
Still another difference between this embodiment and the first embodiment resides in arrangement of the outer fins 26 of the base 2. In this embodiment, each set of outer fins 26 are radially arranged to facilitate easy flow of outer airflow between each adjacent pair of the outer fins 26 to thereby promote the heat-exchanging efficiency.
In view of the above, through design of the inner flow path 101 and the outer flow path, heat exchange is carried out between an assembly of the inner and outer fins 25, 26 and air within the inner flow path 101 and the outer flow path, so as to dissipate heat into the surroundings by thermal convection. Furthermore, due to the streamline shaped structures of the outer fins 26, the length of the outer flow path is increased to promote the heat-exchanging efficiency. Further, the inner flow path 101 has a shrunk portion corresponding to the second tube part 22 to allow for an increase in the flow rate of the inner airflow within the second tube part 22, such that the cooling efficiency is promoted, thereby solving the problem of dissipating heat from the light-emitting unit 3.
With this invention thus explained, it is apparent that numerous modifications and variations can be made without departing from the scope and spirit of this invention. It is therefore intended that this invention be limited only as indicated by the appended claims.
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