LED lamp with at least one LED module with heat sink

A LED lamp includes LED modules. Each of the LED modules includes a heat sink body having a first terminal, a second terminal opposite to the first terminal, an airway having an opening at the second terminal, and a side hole on the side surface of the body. The side hole communicates with the corresponding airway. The LED modules are aligned to form concentric circles including an inner circle and an outer circle. The length between the first and the second terminals of each LED module at the inner circle is longer than that at the outer circle. Accordingly, heat generated by LEDs on the first terminals can be dissipated through the airways and the heat sink bodies.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priorities of Chinese application No. 201610586654.6 filed on Jul. 22, 2016, Chinese application No. 201610826238.9 filed on Sep. 14, 2016, and Chinese application No. 201610854761.2 filed on Sep. 27, 2016, and the entirety of which is incorporated by reference herein.

BACKGROUND

Technique Field

The present invention relates to an LED lamp and in particular relates to an LED lamp comprising at least one LED module with a characteristic of high heat-dissipation.

Description of the Related Art

LED lamps are widely used to replace conventional incandescent lamps in the market because of their advantages of long life-time, small size and power saving. Heat-dissipation is a very important consideration during design. China laid-open publication No. 104251476A discloses an LED module with a vertical convection heat-dissipation structure, comprising an optical assembly, a substrate, an LED light source and a heat sink, wherein the optical assembly is fixedly connected to the heat sink. The LED module further comprises a heat-dissipation column disposed on one side of the heat sink, wherein a vent is formed in the central of the heat sink to form a vertical heat-dissipation structure. Accordingly, a better heat-dissipation property can be provided to a lamp with narrow space. However, the LEDs are usually distributed on the edge of the bottom surface of the heat sink which will result in an LED module with a larger size, and the vertical convection heat-dissipation will be highly reduced when more LED modules are incorporated. It's a tradeoff between the numbers of LED modules and the heat-dissipation. Besides, the conventional LED modules are suffering from the problems of low recycling rate, different heat sinks for different LED modules with various powers, and high costs for development of various LED modules.

In order to resolve above-mentioned disadvantages, China laid-open publication No. 103322536A discloses an LED aluminum pipe drilling efficient heat-dissipation device, comprising a heat-dissipation aluminum plate, a plurality of mounting holes, a plurality of aluminum pipes installed in the mounting holes and located on the same side of the heat-dissipation aluminum plate, and a plurality of heat-dissipation holes are arranged on the aluminum pipes. Accordingly, the heat generated by the LEDs can be efficiently dissipated into air through the aluminum pipes and the heat-dissipation holes, and the LED aluminum pipe drilling efficient heat-dissipation device can be conveniently installed. However, the numbers of the aluminum pipes corresponding to the LEDs will increase with the numbers of LEDs, when many LEDs/pips are installed, the heat convection effect may be lowered even a plurality of drilling holes are formed on the crowded aluminum pipes.

SUMMARY

To address the above-mentioned issues, an LED lamp comprising at least one LED module with high heat-dissipation effect is provided.

According to an embodiment of the LED lamp, the LED lamp comprises a plurality of LED modules. Each of the LED modules comprises a heat sink body having a first terminal, a second terminal opposite to the first terminal, an airway having an opening at the second terminal, and at least one side hole on the side surface of the body, the at least one side hole communicates with the airway. The plurality of LED modules are aligned to form concentric circles including an inner circle and an outer circle. The length between the first and the second terminals of each of the plurality of LED modules at the inner circle is longer than the length between the first and the second terminals of each of the plurality of LED modules at the outer circle.

According to an embodiment of the LED lamp, the LED lamp further comprises a plate. The plate comprises a plurality of mounting holes thereon. Each of the plurality of LED modules comprises a connecting part corresponding to one of the heat sink body. Each of the connecting part is on the first terminal of the corresponding heat sink body. The plurality of LED modules is connected with the plurality of mounting holes, respectively.

According to an embodiment of the LED lamp, the area between the inner tangent line of the mounting holes on the inner circle and the outer tangent line of the mounting holes on the outer circle is one to four times of the total areas of the plurality of mounting holes.

According to an embodiment of the LED lamp, each of the plurality of heat sink body comprises a stepped surface at the second terminal of the heat sink body. The stepped surface comprises an upper inclined surface, a lower inclined surface, and a shoulder surface connected between the upper and the lower inclined surfaces. A distance from the plate to the lower inclined surface of each of the plurality of LED module at the inner circle is longer than a distance from the plate to the upper inclined surface of each of the plurality of LED modules at the outer circle.

According to an embodiment of the LED lamp, the ratio of the height h1of the connecting part over the height H of the LED module is about 0.04 to 0.25, and the ratio of the height h2of the shoulder surface to the height H of the LED module is about ⅙ to ½.

According to an embodiment of the LED lamp, a position of each of the openings of the plurality of the LED modules at the inner circle is higher than, from the plate, a position of each of the openings of the plurality of the LED modules at the outer circle.

According to an embodiment of the LED lamp, a position of each of the openings of the plurality of the LED modules at the inner circle is higher than, from the plate, a position of the corresponding second terminal of the plurality of the LED modules at the outer circle.

According to an embodiment of the LED lamp, the LED lamp comprises a plurality of LED units. Each of the plurality of LED units comprises three of the plurality of LED modules adjacent to each other. One LED module of each of the plurality of LED units is arranged on the inner circle and the other two LED modules of each of the plurality of LED units are arranged on the outer circle.

According to an embodiment of the LED lamp, each of the three LED modules of each of the LED units has a trench on the surface adjacent to the other two LED modules. The longitudinal axes of the trenches are substantially parallel to the longitudinal axes of the heat sink bodies of the LED units. The three adjacent trenches forms a channel with a first aperture and a second aperture opposite to the first aperture.

According to an embodiment, a heat sink for an LED module comprises a heat sink body. The heat sink body has a first terminal, a second terminal opposite to the first terminal, an airway having an opening at the second terminal, and a side hole on the side surface of the body. The side hole communicates with the airway. A surface of the second terminal is a stepped surface or an oblique surface.

According to an embodiment, the heat sink body comprises a stepped surface. The stepped surface comprises an upper inclined surface, a lower inclined surface, and a shoulder surface connected between the upper and the lower inclined surfaces. The longitudinal axis of the shoulder surface is substantially parallel to the longitudinal axis of the airway.

According to an embodiment, the shoulder is substantially on the same surface as the longitudinal axis of the airway on.

According to an embodiment, the upper inclined surface and the lower inclined surface are not substantially parallel to each other.

According to an embodiment, the heat sink body comprises an oblique surface. the normal line to the oblique surface and the longitudinal axis of the airway creates an acute angle.

According to above description, the longer length of the LED modules at the inner circle than that at the outer circle increases efficiency of heat-dissipation from the LEDs. The side holes and the airways could individually or jointly improve thermal convection of the LED modules. The arrangement of the LED modules and the plate further makes the second terminals at the inner circle exposed and not being blocked by the second terminals at the outer circle. Hence, efficiency of heat-dissipation is further improved. The stepped surfaces at the second terminal increase the area of the opening of the airways at the second terminals. Accordingly, thermal convection is further improved. The feature of the position of the openings of the airways at the inner circle are higher than that at the outer circle improves thermal convection furthermore. The trenches of the plurality of LED units could improve the thermal convection as well.

DETAILED DESCRIPTION

The making and using of the embodiments of the present disclosure are discussed in detail below. However, it should be noted that the embodiments provide many applicable inventive concepts that can be embodied in a variety of specific methods. The specific exemplary embodiments discussed are merely illustrative of specific methods to make and use the embodiments, and do not limit the scope of the disclosure. Furthermore, the terms “longitudinal axis”, “top”, “bottom” are used to distinctly explain the relative positions of the elements depicted in the embodiments instead to limit the scope of this invention. Moreover, the terms “substantially perpendicular” and “horizontal” are defined as ±30% of the standard definition thereof. For example, the standard definition of “substantially perpendicular” is 90 degrees to a base line, but it is defined as the angle ranging between 60 to 120 degrees in this present invention.

The embodiment 1 will be described below with reference to the accompaniedFIGS. 1 to 4. First, please refer toFIG. 1, which is a perspective view of the embodiment 1 of an LED lamp100. As illustrated inFIG. 1, the LED lamp100comprises a plate4, a plurality of LED modules1mounted on the plate4, a plastic casing2and a lamp base3. The lamp base3is used to interconnect with a power supplying source (not shown) and provides electrical power to drive the LEDs (not shown) of the LED modules1.

As illustrated inFIG. 2, the shape of the plate4is substantially circular, and plates with other suitable shapes can also be selected as the plate4in other embodiments. A plurality of mounting holes41are formed on the plate4, and each of the LED modules1is inserted into each of the mounting holes41and fastened therein to expose the LEDs (light emitting diodes) formed on the LED modules1. The mounting holes41of this embodiment are circular countersunk-head holes, and each LED module1is supported by the structure of each circular countersunk-head hole. Countersunk-head holes with other shapes can also be chosen based on the shape of the cross-section of the heat sink10. As illustrated inFIGS. 1 and 2, each of LED modules1is independently mounted onto the plate4by being inserted into the corresponding mounting hole41. The LED modules1can also be assembled together first to form an assembly of the LED modules, and the assembly of the LED modules is mounted onto the plate4thereafter. As illustrated inFIG. 2, a plurality of screw holes42are formed on the plate4and located between the center of the plate4and the mounting holes41. The bottom (not labeled) of the plastic casing2is fixed on the plate4by screwing with screws5from the screw hole42on the plate4to the screw holes21on the edge of the bottom of the plastic casing2. The lamp base3formed on the top of the plastic casing2is used to connect with a corresponding lamp socket (not shown).

The LEDs30of the LED modules1are interconnected with each other for example in series. In the embodiment where the LEDs are connected in series, the in-series-connected LEDs are connected with a power supplying source shown). Specifically, the LED at one end of the in-series-connected LEDs is connected with cathode of the power supplying source and the LED at the other end of the in-series-connected LEDs is connected with anode of the power supplying source. A wire hole (not shown) may be formed at the center of plate4(the center of the circle tangent to the screw holes42) so that after the LEDs installed on mounting holes41by a conductive wire (not shown), the conductive wire may pass through the wire hole to electrically connected to the lamp base3and power supplying source.

Next, please refer toFIG. 3A, which illustrates an LED module1as shown inFIG. 1. As illustrated inFIG. 3A, each of the LED modules, comprises a heat sink10, a connecting part20capped on the heat sink10, and an LED30on the connecting part20. The LED30may comprise an LED chip (not shown) packaged with a lead frame (not shown). The heat sink10comprises a heat sink body101having a first terminal (not labeled) and a second terminal (not labeled) opposite to the first terminal (not labeled), an airway11communicating the first terminal (not labeled) and the second terminal (not labeled), and a stepped surface13at the second terminal (not shown) of the body101. (In another embodiment, the airway11has opening at the second terminal, but does not communicate with outer air through the first terminal. In other words, the end of the airway11at the first terminal is blocked. The body101of this embodiment is a hollow tube with a circular cross-sectional area, and the inlet and the outlet of the airway11are of the same diameter to ensure that the heat generated by the LED30can be dissipated evenly. A hollow tube with a cross-sectional area of other shape such as rectangular can also be selected as the body101in other embodiments. The body101can be made of materials with good thermal conductivities, such as aluminum alloy 1070 , 1050, 6061 and 6063, and preferably aluminum alloy 6063. The body101can also be made of other materials with good thermal conductivities in other embodiments. The connecting part20can be made of aluminum alloy, and preferably aluminum alloy6063. The connecting parts20corresponds to heat sink body101and are, respectively, on the first terminal of the corresponding heat sink body. In one embodiment, the connecting part20is joined with the heat sink10by a glue (not shown) with a high thermal conductivity, and the LED30is on the connecting part20by the glue (not shown) with a high thermal conductivity. By means of the glue with a high thermal conductivity, the heat sink10, the connecting part20and the LED30can be easily joined together with less cost. As illustrated inFIG. 3A, the ratio of the height h1of the connecting part20over the height H of the LED module1is about 0.04 to 0.25 to ensure that an attractive appearance can be fabricated with minimal cost.

As illustrated inFIG. 3A, heat sink body101comprises a stepped surface13at the second terminal (not labeled) of the body101, where is away from the connecting part20. The airway11is partially exposed along its axis by means of the stepped surface13. The stepped surface13comprises an upper inclined surface131, a lower inclined surface133, and a shoulder surface132connected between the upper inclined surface131and the lower inclined surface133. In the embodiment, the shoulder surface132extends along the longitudinal axis of the airway11, and preferably the shoulder surface132is substantially on the same surface as the longitudinal axis of the airway11on. In one embodiment, the shoulder surface132may be substantially parallel to the longitudinal axis of the airway11. The ratio of the height h2of the shoulder surface132over the height H of the LED module1is about ⅙ to ½. The angle created by the upper inclined surface131and the horizontal surface (not labeled, the surface perpendicular to the axis of the heat sink body101) is about 45 to 50 degrees. The angle created by the lower inclined surface133and the horizontal surface (not labeled) is about 43 to 48 degrees. The angle created by the shoulder surface132and the horizontal surface (not labeled) is about 43 to 90 degrees. The upper inclined surface131and the lower inclined surface133are oblique to the longitudinal axis of the airway11, and preferably the upper inclined surface131and the lower inclined surface133are oblique to the longitudinal axis of the airway11with the same inclined angle. Either the upper inclined surface131or the lower inclined surface133can also be substantially perpendicular to the longitudinal axis of the airway11in other embodiments.

In other embodiments,FIG. 3Billustrates another LED module1for the embodiment 1 of the LED lamp. The LED module1illustrated inFIG. 3Bfurther comprises at least one side hole12which is formed on the side surface of the body101adjacent to the connecting part20and communicates with the corresponding airway11. The side holes12and its corresponding airway11means the side holes12and the airway11on the same heat sink body101. As illustrated inFIG. 3B, there are four side holes12evenly surrounding the side surface of the body101. The number of the side holes12of other embodiments can be 1, 2, 3 or more. The experiments indicate that a better chimney effect for heat dissipation can be achieved by forming some but not too many side holes12on the circumferential surface at the same axis position of the body101. The chimney effect of heat dissipation will be reduced once the side holes12are formed at different axis positions of the body101. As illustrated inFIG. 3B, the openings121of the side holes12are exposed on the side surface of the body101, whereby a part of the hot air heated by LEDs30enters into the airway11through the side holes12and then the part of hot air flows out of the heat sink body. The rest of the hot air heated by LEDs30can be directly dissipated through the airway11. The heat-dissipation can be enhanced by designing a desired angle between axes of each side holes12and the airway11. Preferably the axis of each of the side holes12is substantially perpendicular to the axis of the airway11. Accordingly, the heat generated by the LED30can be dissipated directly into the airway11and indirectly into the airway11through the side holes12. The ratio of the radius of each side holes12over the radius of the11airway is about ⅛ to ⅗. Preferably, the body101has a thickness of about 1.5 mm to 4 mm, and the ratio of the outer radius of the airway11over the outer radius of the body111is about 0.5 to 0.8, and the distance from the center of the side holes12to the connecting part20is about 6 mm.

When the LED module1is operated, the heat generated by the LED30is conducted to the connecting part20and the heat sink10, and the air within the airway11is heated and expanded, then the hot air goes up to be exhaled out of the heat sink10, and the cold air subsequently enters into the airway11via the side holes12. Accordingly, a small-sized heat-dissipation device with a good thermal convection can be achieved by the chimney effect mentioned above. As illustrated inFIG. 3B, the heat generated by each LED30on each heat sink10can be individually dissipated through the corresponding airway11of each heat sink body. Accordingly, the heat generated by a plurality of LEDs can be more efficiently dissipated respectively through corresponding airways than through a same airway. Moreover, the size of the heat sink can be greatly minimized and the heat-dissipation efficiency can be highly enhanced. In comparison with a device with the LEDs around the center of the plate4or a device with the LEDs surrounding the area corresponding to the center of the plastic casing2, the above-mentioned embodiment with the LED modules mounted around the outer edge of the plate4could emit similar optical power but have the advantages of better heat-dissipation efficiency, lower production cost, and smaller overall size.

In other embodiments, as illustrated inFIGS. 3C and 3D, at least one channel202is further formed on the side surface of the connecting part20of the LED modules1. Each channel202comprises an axial section (not shown) and a radial section (not shown) communicating with the axial section. The axial section is communicates with the airway11. Accordingly, the channel202provides another pathway for thermal convection.

In other embodiments, as illustrated inFIG. 3E, the LED30on the connecting part20of the LED module1as shown inFIG. 3Dis further capped with a reflector40to prolong its lifetime. Similarly, the LED30on the connecting part20of the LED modules1as shown inFIGS. 3A˜3C can also be capped with the reflector40. Furthermore, the chip (not shown) of the LED30of other embodiments can be further be encapsulated by a lens (not shown) to adjust the emitting angle of the LED lamp100.

The LED lamp200illustrated inFIG. 4is similar to the LED lamp100. The LED modules5of the LED lamps200is different from that of LED lamp100.

As illustrated inFIGS. 5A˜5E, the structure of the LED module5is similar to that of the LED modules1as illustrated inFIGS. 3A˜3E. The heat sink body171of the heat sink17of the LED module5has an oblique surface14at the second terminal instead of a stepped surface13. The normal line to the oblique surface14and the longitudinal axis of the airway141creates an acute angle. Preferably the angle is less than 60 degrees. The thermal convection can be enhanced by the oblique surface14and the heat generated by the LED30can be dissipated more efficiently. As for the side holes12and channel202illustrated inFIGS. 3B˜3E can also be formed on the LED module5illustrated inFIGS. 5B˜5E to enhance the heat-dissipation of each LED30. Details of the side holes12and channels202will not be repeatedly discussed.

The embodiment 3 will be described below with reference to the accompaniedFIGS. 6 to 11. The LED lamp300of this embodiment is similar to the LED lamp100disclosed in the embodiment 1 and the LED lamp200disclosed in the embodiment 2. As illustrated inFIG. 6, the LED lamp300comprises a plate4, a plurality of LED modules1or5mounted on the plate4, a plastic casing2and a lamp base3. The lamp base3is used to interconnect with a power supplying source (not shown) and provides electrical power to drive the LEDs (not shown) of the LED modules1or5. The LED modules1or5illustrated inFIGS. 3A˜3E andFIGS. 5A˜5E can all be utilized in the LED lamp300of this embodiment. The LED module1illustrated inFIG. 3Eis taken as an example in this embodiment for exemplary description.

As illustrated inFIGS. 6 and 9, the plurality of LED modules1A and1B are aligned to form concentric circles including an inner circle and an outer circle. Each of the LED modules comprises a heat sink body having a first terminal and a second terminal. The length between the first terminal and the second terminal of each LED modules1A at the inner circle is longer than that at the outer circle. Hereinafter, the LED modules at the inner circle is referred as inner LED modules1A and the LED modules at the outer circle is referred as outer LED modules1B. The height H1(from the plate4to the top of the second terminal) of the inner LED module1A is greater than the height H2of the outer module1B. As illustrated inFIG. 6, the height of the lamp base relative to the plate4, height H1(the height of the inner LED module1A relative to the plate4), and height H2, the height of the outer LED module1B relative to the plate4, decrease in order to form a tower-shaped LED lamp300. As illustrated inFIG. 10, the lower inclined surface133of the heat sink10in the inner LED module1A is preferably higher than the upper inclined surface131of the heat sink10in the outer LED module1B. This tower-shaped LED lamp300possesses not only a characteristic of high heat-dissipation but also an attractive appearance with an advantage of power saving. The height of each heat sink10in the inner LED module1A is about 60 to 100 mm, and the height of each heat sink10in the outer LED module1B is about 40 to 70 mm. The inner diameter of the heat sink10is about 8 to 16 mm, and the outer diameter of the heat sink10is about 14 to 20 mm. In other embodiments, the design with an outer LED module1B taller than an inner LED module1A can also be adopted. In this embodiment, the second terminal of the inner LED modules1A are totally exposed and not blocked by the second terminals of the outer LED modules1B. However, in another embodiment, the second terminals of the outer LED modules1B may block a portion of the second terminals of the inner LED modules1A. In another embodiment, the position of each of the openings of the inner LED modules1A is higher than, from the plate4, the position of the openings of the outer LED modules1B. Specifically, the openings of the inner LED modules1A may be totally or partially higher than that of outer LED modules1B. In another embodiment, the position of the openings of the inner LED modules1A is higher than, from the plate, the position of the corresponding second terminals of the outer LED modules1B. In other words, the second terminals of the outer LED modules1B my block a portion of the openings of the airways at the second terminals of the inner LED modules1A.

As illustrated inFIG. 7, a plurality of mounting holes41are formed on the plate4and arranged to surround the plastic casing2to form an inner circle (not labeled) and an outer circle (not labeled). The area between the inner tangent line A of the mounting holes41in the inner circle (not labeled) and the outer tangent line B of the mounting holes41in the outer circle (not labeled) is almost 1 to 4 times of the total areas of the mounting holes41in the inner circle (not labeled) and the outer circle (not labeled), and preferably 1.2 to 4 times of the total areas of the mounting holes41in the inner circle (not labeled) and the outer circle (not labeled).FIG. 8illustrates the angle α between the centers of two adjacent mounting holes41of the same circle the plate4, and the angle β between the edges of two adjacent mounting holes41of the same circle on the plate4. The angle α is determined by the numbers of LED modules1, and preferably ranges from 18 to 40 degrees. The angle β is less than 10 degrees. The outer LED modules1B of this embodiment comprises about 15 to 25 LED modules1, and the inner LED module1A of this embodiment comprises about 8 to 16 LED modules1. The LED modules1of the same circle are spaced with each other by about 10 to 30 mm, and the LED modules1between the inner circle and outer circle are spaced with each other by about 14 to 22 mm.

As illustrated inFIGS. 9&10, the plate4further comprises a flange43formed along the edge of the plate4, wherein the inner surface43aof the flange43is inclined relative to the upper surface4aof the plate4, and a trench6is formed between the inner surface43aof the flange43and the upper surface4aof the plate4. Therefore, sufficient air can be introduced into the thermal convection via the opening121of the side holes12by means of the trench6to facilitate the heat dissipation. The side holes12can be formed on lower side surface of the body10than before by means of forming the trench6to provide sufficient air and elongate the path of thermal convection, which provides a heat sink with a smaller size and better thermal dissipation.

Please refer toFIG. 11. In this embodiment, the LED lamp comprises a plurality of LED modules arranged to form concentric circles including an inner circle and an outer circle. The LED lamp comprises a plurality of LED units1′. Each of the plurality of LED units1′ comprises three of the plurality of LED modules1A,1B,1C adjacent to each other. One LED module1A of each of the plurality of LED units1′ is arranged at the inner circle while the other two LED modules1B,1C of each of the plurality of LED units1′ are arranged at the outer circle. Hereinafter, the LED module1A at the inner circle is referred as the first LED module1A and the LED modules1B,1C at the outer circle are referred as the second and third LED modules1B,1C. As illustrated inFIG. 11, the first LED module1A, the second LED module1B and the third LED module1C are attached to each other to form a triangle. Each of the three LED modules1A,1B,1C of each of the LED units1′ has a trench on the surface adjacent to the other two LED modules. For example, a first trench15ais formed on the outer surface1aof the first LED module1A along the longitudinal axis of the first LED module1A; a second trench15bis formed on the outer surface1bof the second. LED module1B along the longitudinal axis of the second LED module1B; and a third trench15cis formed on the outer surface1cof the third LED module1C along the longitudinal axis of the third LED module1C. The first trench15a, the second trench15band the third trench15care linked to each other to form a cavity15with a first aperture (not labeled) and a second aperture (not labeled) opposite to the first aperture (not labeled). The cavity15can be functioned as an additional thermal convection structure, which can further enhance the heat dissipation of the LED modules1A,1B,1C of each of the LED units1′. The shapes of the cross-sections of the trench15a,15band15care arcs with an arc angle of around 120 degrees, in this embodiment. In other embodiments, trenches with suitable cross-sectional areas can also be selected as the trenches15a,15band15c. The LED lamp can comprise at least one of the LED unit1′, and the LED unit1′ can comprise more than 3 LED modules.

As mentioned above, the LED modules of some embodiments can be selected and assembled in many ways to generate LED lamps with various power, which can not only reduce the fabrication cost but also facilitate the assembly of the LED lamps.