RU2547460C2 - Lighting module with light-emitting diodes (led) - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to electric engineering and can be used for manufacture of lighting fixtures with powerful modular LED crystals. The lighting module consists of LED crystal, a circuit board, a reflector and a radiator, characterized by that the board with the crystal, the reflector and the radiator are made from a single piece of metal with good heat conductivity and high reflection coefficient. The reflecting radiator is made using the method of transverse-longitudinal bending with minimum strain of initial material; extra material formed during moulding is drawn into stiffening ribs of variable height, it provides heat removal from the reflector and the panel with the LED crystal, without intermediate elements. Technological preparation of the reflecting surface is performed using a work piece in expanded form before the moulding operation, and the sizes the work piece and the heat dissipating stiffening ribs are found from the mathematical expression.

EFFECT: decrease of thermal resistance along the path of the thermal flow from the crystal to the radiator and improvement of the thermal mode.

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Description

The present invention relates to the field of lighting engineering and can be used in the manufacture of LED light sources with powerful, super-bright and block crystals. It is known that the efficiency of a lighting device to a certain extent depends on the light output of the light source used and its light distribution. Advances in scientific research and LED technology have allowed LEDs to advance into a number of the most promising light sources, which, in terms of light output, have reached values that correspond to the best discharge light sources at present, and exceed their service life.

Significant recent successes have been achieved in the production of lighting modules with powerful, super-bright and block crystals, which provide a large luminous flux in light fixtures that are small in volume and overall dimensions.

An important task in the design of LED lighting devices is to create the optimal temperature regime at the “pn” junction of the emitting crystal. With an increase in the power released on the crystal, the heat energy released in it increases accordingly, the temperature rises and, as a rule, the luminous flux of the module decreases, its useful life decreases, and the color temperature of the crystal radiation changes. To ensure acceptable technical parameters of the modules, means are used to reduce and stabilize the thermal regime at an acceptable level. The most common way of removing thermal energy from the “p-n” junction of a crystal is to use radiators of various structural and technological designs. Widespread solid cast and stamped multi-leaf prefabricated structures, made in most cases from aluminum with a high coefficient of thermal conductivity.

A typical example of a cast light-emitting diode LED light source is an FHILIPS MASTER LED spot shape lamp 16W 2700K 230V PAR38 OD (1). The heat-dissipating radiator, wiring panel, reflector and secondary optics are made in the form of separate elements, combined with fasteners and assembly operations in a single LED module. Given the multi-tiered design, the product is characterized by high complexity and high thermal resistance in the path of heat flux from the crystal to the radiator. The product has a high specific gravity per 1 watt of power dissipation; so, with a total power of 16 watts, its mass, determined mainly by the mass of the radiator, is 600 grams, while despite its large mass, its useful life is 22,000 thousand hours, which is relatively low for an LED light source.

A higher service life - 45,000 thousand hours - was achieved in lamps of the same company MASTER LED spot 16W 2700K 230V PAR38 25D (1) due to the use of more efficient heat dissipation by a cast aluminum radiator with a more developed (increased) heat dissipating surface. However, the mass of the module also increased significantly - up to 690 grams.

A similar solution with the same characteristics was adopted in the well-known BARTON LED d122 ∗ 136 15W par38 AC220-240V 2700K lamps (2).

A typical example of a prefabricated radiator consisting of a set of separately stamped plates are the Nuventix radiators presented at the Strategies in Light (SIL) conference in 2013, used in products of the R150-170 series (3). The design provides the necessary thermal regime of the crystal, but differs in great complexity in manufacturing.

An important role in the overall chain of heat transfer from the LED crystal to the radiator is provided by the design of mounting the crystal on a board, which in most cases is installed on the radiator. Of the many known methods of installing crystals, the most effective from the point of view of heat transfer efficiency is the fastening option in the design of COW (Chip on Board - “chip on board”), which are soldered directly to a printed (mounting) board (4).

Another most important task of a correctly designed module is to provide a given effective light distribution for a particular lighting installation. The light intensity curve of light modules is formed, as a rule, in three ways: due to secondary optics, by lenses using the laws of refraction at the interface between two media, using external reflectors based on the laws of reflection and diffusers from light-scattering materials, for example, milk or opal glasses. The latter option, based on the scattering of the light flux of the light source, has very limited possibilities in terms of controlling the light flux and is characterized by large losses of light in the thickness of the light-scattering material.

The use of secondary optics to control the luminous flux of high-power, super-bright, and block crystals has certain limitations. Thus, with an increase in the power of crystals, the thermal load on the optics, which is made, as a rule, from translucent plastics with limited heat resistance, increases. As the temperature rises and approaches its maximum permissible material, the lens material undergoes accelerated destruction, the light transmission of the lenses decreases, and the life of the light module as a whole decreases. A decrease in temperature on secondary optics is possible due to a substantial increase in its size, which leads to an unacceptable, for economic reasons, increase in the consumption of expensive materials.

Considering the above, for working in modules with powerful, superbright and block crystals, the most rational is the use of reflective systems, using aluminum as the structural material for these purposes, characterized by a higher operating temperature, good thermal conductivity and high reflection coefficient - up to 98% (5 ) within the entire visible radiation spectrum.

The solution closest to the proposed invention is the MASTER LEDspot 17-100W 2700K PAR38 OD (6) LED lamp from FHILIPS. The lamp consists of a block of crystals mounted on a circuit board, flat in the shape of a reflector mounted on the inner supporting surface of the radiator. Secondary optics in the form of a block lens and a protective glass with a slightly frosted surface are mounted on the radiator coaxially with the crystals. The radiator is made by injection molding technology, structurally made in the form of a bearing support, surrounded by lateral heat dissipating fins. The radiator, reflector, circuit board and secondary optics are made by separate structural elements and combined by corresponding fasteners into a single LED module. The proposed constructive solution allowed to slightly improve the parameters of the product compared to the prototype; thus, the service life is increased from 22,000 thousand to 25,000 thousand hours. However, the latest model of the product has significant drawbacks: the mass of the product, as before, remains too large compared to the mass of the replaced halogen lamp, all the elements are made separately, and therefore, in places where they are joined into a single structure, there is additional resistance to heat flux going from the crystal to the heat dissipating radiator. Due to the fact that the secondary optics are made of plastic, the thermal load, and hence the power of the installed crystal, is very limited due to possible overheating and destruction of the lens material. The multi-tiered design leads to an increase in the complexity, material consumption and cost of the product as a whole. A wide gapless ring along the lower radiator circuit makes it difficult for the air to flow freely into the area of the cooling fins, thereby reducing the efficiency of their heat dissipation.

Based on the foregoing, it is proposed the design of a lighting module with powerful, super-bright and block crystals, eliminating the disadvantages noted above. The module of figure 1 consists of a crystal 1, a universal radiator 2, combined into a single unit with a reflector and a mounting plate 3 with conductive contacts, a protective glass 4 (in a sealed version of the module) and a support ring 5. The universal radiator, mounting plate and reflector are made as one piece from a single piece of metal with effective thermal conductivity and high reflection coefficient (hereinafter referred to as the radiator). The radiator is made of a flat billet 6, by longitudinally-transverse bending with minimal deformation, the excess metal in the molding process is doubled and pulled into ribs of variable height 7, located radially along the contour, the ribs remove heat from the universal radiator and through it from the LED crystal to the surrounding space, at the same time ribs give the necessary rigidity and dimensional stability to the entire system of a universal radiator; the area of the radiator between the ribs - facets, has a design shape and provides a given light distribution; in the upper part of the radiator there is a flat platform 3 - the basis of the circuit board. In order to give the radiator sufficient shape stability in the equatorial section, an annular rift 8 is made at the base. In a sealed version, in the case with a protective glass, to fasten the glass 4 and give the radiator the necessary shape stability, a special ring 5 is put on and pressed onto it from the bottom, which surrounds the radiator along the contour and stamped trunnions 9 of figure 2, 3 compresses the ribs 7, providing dimensional stability and tightness of the structure. The trunnions 9 of the ring of FIG. 3 are stamped and bent from the base of the ring, thus formed in the places of stamping the trunnions of the holes 11 of FIG. 3, provide unhindered movement of air in the way of its natural movement, from bottom to top, along the outer surface of the radiator, ensuring its efficient cooling.

The design of an open LED module with a stiffness rift is shown in Fig. 4, and a general view of a radiator with a regular macro-relief to it is shown in Fig. 6.

The design of the LED module with a protective glass and a support ring is shown in Fig.2, 5, and a General view of the radiator with a regular macro-relief to it is shown in Fig.7.

To solve a number of specific lighting problems, high uniformity of the light beam and the absence of spotting on the illuminated surface are required. In practice, such problems are solved using plate reflectors (7), in which reflective plates are located along the profile contour of the mirror reflector so that their midpoints touch the skeleton of the reflector tangentially. A practical example of such a solution is the creation of an irregular macrorelief on the reflector surface with cells located tangent to the radiator profile and with dimensions many times greater than the transverse dimensions of the crystal emitting light. A general view of a radiator with a macrorelief is shown in FIG. 6 — a variant with a rift, and in FIG. 7 — a variant without a rift in the equatorial plane. In the proposed technical solution, the molding of the macrorelief, the creation of a reflecting surface with a high reflection coefficient and the protection of the reflecting surface from environmental influences are performed before the operation of forming the radiator on a flat workpiece, while the dimensions of the workpiece and heat-dissipating stiffeners are determined from the ratios:

S = π * (R _r + L _max ) ^2;

D = 2 * (R _r + L _max );

, где $$h=\frac{\pi \ast \left(R{}_r+L+R_p\right)}{N}$$

where

S is the estimated area of the radiator blank;

D is the diameter of the workpiece;

L _max - the maximum length of the arc of the radiator profile from the neck to the base of the radiator;

h - rib height at the current point of the working profile;

R _r is the radius of the neck (circuit board) of the radiator;

L is the length of the arc of the working profile from the neck to the current point of the working profile of the radiator;

R _p is the radius of the inner circumference of the working profile in a section perpendicular to the axis of the radiator and passing through the current point of the working profile;

N is the number of heat dissipating ribs.

Information sources

1. Catalog of lamps. FHILIPS. 2010-2011

2. Catalog of lamps. OSTEC. 2013 year

3. Semiconductor lighting technology. No. 3, 2013, Accent Group LLC.

4. Semiconductor lighting. No. 3, 2010, Accent Group LLC.

5. Lighting engineering. No. 1, 2013, Agency Sea LLC.

6. Catalog of the company FHILIPS. 2013 year

7. Lighting devices (theory and calculation). V.V. Trembach, Glavpoligrafprom, 1972

Claims (1)

Lighting module with LEDs (LED module), consisting of an LED crystal or block of crystals, a circuit board with current-carrying contacts, a reflector for controlling the light flux of the LED crystal, a radiator for cooling the core of the crystal and a protective glass, characterized in that the circuit board, the reflector and the radiator of the module are made as a whole from one piece of metal, ribs of variable height are located radially along the contour and represent twice the excess metal formed in the process forming radiator fins stiffen the entire system in the meridional plane; the radiator region between the ribs performs the function of a reflector, provides the required light distribution for solving a specific lighting task; the neck is made in the form of a flat platform, serves as the basis of the wiring panel and provides heat removal from the LED mounted directly on it to the radiator and further into the surrounding space without intermediate heat-insulating elements; in the lower part of the radiator there is a transverse annular rift to give the reflector rigidity in the equatorial plane and a support ring with a seat corresponding to the inner diameter of the radiator, with pins tightly compressing and fixing the meridional ribs; holes are provided along the contour of the ring, freely passing and directing air upward along the fins cooling the radiator; the structural dimensions of the module elements are related by the ratio:

Where
h - rib height at the current point of the working profile;
R _g - the radius of the neck (circuit board) of the radiator;
L is the length of the arc of the working profile from the neck to the current point of the working profile of the radiator;
R _p is the radius of the inner circumference of the working profile in a section perpendicular to the axis of the radiator and passing through the current point of the working profile;
N is the number of heat dissipating ribs.

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