JP5513472B2 - Lamp unit and signal lamp using the same - Google Patents

Description

  The present invention relates to an LED lamp having a cooling mechanism using a composite heat dissipation system, which is mainly used for traffic signal lights.

  Traffic signal lights must continue to operate reliably and with a long service life in order to ensure traffic safety, which is the purpose of use.

  In recent years, instead of a light bulb, a light emitting diode (LED) is used for a traffic light (see, for example, Patent Document 1). In order to ensure the reliable operation of the traffic signal lamp, it is necessary to drive the LED in an appropriate temperature range. Therefore, it is necessary to examine the heat dissipation mechanism of the LED lamp so that the temperature of the LED does not rise excessively.

  On the other hand, when replacing a traffic signal light bulb that used a light bulb other than an LED with an LED, it is conceivable to replace the entire light box. However, in order to reduce costs and labor, a conventional light bulb is used. In many cases, the conventional light box or lamp unit is used as it is, and only the bulb part inside is replaced. Therefore, it is necessary to dissipate the heat of the LED even in the conventional lamp unit.

When a forward bias is applied to the LED and an electric current is passed, energy released by recombination of free electrons and holes of carriers injected at the PN junction is converted into light and light is emitted. The amount of emitted light is proportional to the amount of free electrons and holes that are injected and recombined. Since the current is a carrier injection amount per second, the current amount and the light emission amount are in a proportional relationship.
LED light emission is caused by recombination of carriers injected in the active region of the PN junction through a current in the forward direction of the voltage-current characteristic of the LED shown in FIG. In order to enable injection, it is necessary to apply a forward voltage about the diffusion potential between the terminals of the LED from the outside, and this voltage value is called a rising voltage. The current characteristics at a voltage exceeding this voltage value are such that the current increases rapidly with a slight increase in voltage, and is close to a constant voltage characteristic.

Therefore, one LED in the light emitting state consumes the power of the product of the element voltage value and the current value which are substantially equal to the rising voltage, and the number of lamps using N is N times that. Of the power consumption, only a small amount is converted to light, and most of it is heat.
This heat generation self-heats the LED itself and raises its temperature. Therefore, in order to continue light emission stably, it is necessary to dissipate heat and cool the LED. That is, in order to obtain a target stable and long-life LED lamp, it is necessary to comprehensively examine the temperature rise due to heat generated from the LED by energization and the thermal balance of the heat dissipation mechanism for cooling.

  Since the LED has a property sensitive to the temperature inherent to the semiconductor electronic device, as shown in FIG. 12B, there is an upper limit for the ambient temperature at which the LED can operate properly. In addition, there is an upper limit for the amount of current that can be energized with respect to the ambient temperature, and the allowable operating range that they enclose is specified by the LED manufacturer, and the ambient temperature and operating current are limited to various values within this range. There must be.

In actual use, the ambient temperature of the LED is a value obtained by adding the temperature rise due to heat generation to the external environment temperature where the LED is placed.
Therefore, in an LED lamp device that is used in a high external environment temperature, the amount of temperature increase due to heat generation that is allowed increases as the external environment temperature increases. Here is the importance of cooling by heat dissipation.
If the cooling can be performed effectively, the temperature rise due to heat generation can be reduced, the LED lighting operation can be within the allowable operating range, and an appropriate lighting operation can be obtained.
In addition, it is well known that an electronic device that is an assembly of electronic components has an unfavorable effect on lifespan, and cooling is effectively performed and it is extremely difficult to reduce the temperature to an appropriate temperature. This is an important device configuration technology.
That is, the effective heat dissipation type cooling method according to the present invention is an extremely important technology for LED lamps used in traffic signal lamps for vehicles.

  An appearance of a light box 53 of a conventional vehicle traffic signal lamp 51 is shown in FIG. As shown in FIG. 15A, the signal lamp 51 has a lamp box 53 in which usually three blue, yellow, and red lamp units 101 are installed side by side. FIG. 15B is a sectional view taken along the line B-B ′ of FIG. 15A, and the lamp unit 101 is provided inside the lamp box 53. An LED lamp 103 is provided in the lamp unit 101 and irradiates the signal color light 55 in front of the signal lamp 51.

  As is apparent from the manner in which the LED lamp 103 is attached to the lamp unit 101, in order to emit signal-colored light to vehicles on the road, the LED lamp 103 is in a sideways state in which the optical axis of the LED lamp 103 is slightly downward and close to horizontal. Often used.

  In a vehicle traffic signal lamp, an LED lamp is sealed in a lamp unit, and the optical axis is mounted in a substantially horizontal state. Consider a state in which the LED lamp placed in the sealed state of the lamp unit has started to emit light. The light emitted from the LED lamp is radiated to the outside, but the heat generated by the LED light emission operation and the power consumption in the LED drive power supply circuit and the like starts to heat the LED lamp. Further, the heat is trapped in the lamp unit in the closed space, and then is conducted to the external environment and radiated and flows out.

  Therefore, it is required to have effective means to quickly dissipate heat from the inside of the lamp unit to the external environment and cool the inside. Without this means, the internal temperature rise makes the safe operation of the LED lamp difficult and adversely affects the life. Effect. In particular, it is necessary to consider an environment with a high outside air temperature in summer, and a cooling mechanism with a quick response and high reliability must be provided.

  On the other hand, a general illumination light source is suspended from a ceiling or the like and used in a vertical state. Further, the LED lamp is often used in a space open to the external environment. For this reason, the heat generated in the LED lamp generates air convection above the LED lamp, and the LED lamp is always continuously cooled with air substantially equal to the temperature of the space. Therefore, the light source for traffic signal lamps requires a cooling method using a method different from that for general illumination light sources.

  FIG. 16 is a diagram showing a configuration of a lamp unit 101 to which a conventional LED lamp 103 is attached. The LED lamp 103 includes a globe 105 having a function of diffusing light and a cover, an LED 3, an LED board 5 of a metal disk to which a plurality of LEDs 3 are fixed, and a power supply circuit 7 provided at the center part on the back of the LED board part. It has the room part 9 to enclose and the plug 15 connected to the room part 9. In addition, a plurality of cooling heat radiation fins 11 extending vertically from the back surface of the outer peripheral annular portion of the room portion 9 of the LED substrate 5 constitute a heat radiator. The LED lamp 103 is attached to a socket 33 provided with a mounting bracket 31, and power is supplied to the LED lamp 103 via a power cord 35 of the socket 33. After the LED lamp 103 is fastened and attached to the socket 33, the mounting bracket 31 is inserted and fixed from the rear part of the substantially bowl-shaped reflector 25. In the prior art, a gap is provided between the rear end of the radiating fin 11 serving as a radiator and the mounting bracket 31 for the purpose of passing the lamp mounting margin and air carrying heat.

  A front lens 23 is attached to the front portion of the lamp unit 101, and the inside of the lamp unit 101 is sealed. In this state, the lamp unit 101 is attached to the lamp box 53 of the vehicle traffic signal lamp 51 shown in FIG.

The LED lamp 103 is turned on, and a heat dissipation path generated from a heat source mainly composed of the LED lamp 103 is as follows. First, the heat generated from the LED 3 and the power supply circuit 7 of the LED lamp 103 is conducted to the LED substrate 5 and the room 9, and further conducted to the radiation fin 11 that is a radiator, and heats the air in contact with the radiator, Is transmitted to the air. Moreover, the outer side part of the room part 9 is also in contact with air as a heat radiator and radiates heat.
Air heated by a radiator and raised in temperature decreases in density and rises lightly. For this reason, the pressure in the space portion is lowered, and new air in the lower part is gathered and heated there, so that the heat radiation operation is continued. Further, the air in the lamp unit 101 convects in the direction indicated by the air flow 27b.

  The high temperature air rising from the radiator contacts the reflector 25 at the rear of the lamp unit 101 having a large surface area. Since the outer surface of the reflector 25 is in contact with the air at the outside air temperature inside the lamp box 53, the heat of the high-temperature air is transferred to the air at the outside temperature through the reflector 25 as shown in the heat flow 29b. The air inside the lamp unit 101 is cooled. The air whose temperature has been lowered circulates in the lamp unit and is again heated by the radiation fins 11 to carry away heat. Thus, the method of cooling the LED lamp 103 by the cooling mechanism mainly using the heat radiation operation by the radiator is a conventional method, and is widely used in the current LED lamp.

JP 2000-294002 A

  However, for the purpose of realizing LED lamps for vehicle traffic signal lamps with higher safety and reliability, it is necessary to ensure a wide operating range of allowable temperatures even at high ambient temperatures, It is desirable to reduce the amount of increase. However, a solution that simply expands the size of the radiator due to the limitation of the physical size of the lamp that fits the lamp unit and the limitation of the space volume in the lamp unit makes it difficult to cool further. was there.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an LED lamp or the like that can be used for a lamp unit having the same shape as a conventional one and that has a high heat dissipation efficiency.

In order to achieve the above-described object, the following invention is provided.
(1) A substantially bowl-shaped reflector, a front lens that covers the front surface of the reflector, a socket attached to the center of the reflector via a fitting, and a heat transfer pad attached to the fitting And an LED lamp provided with an LED on the front surface of a main body provided with a plug screwed into the socket and a heat radiating fin, and a thin plate shape having wrinkles formed on the heat transfer pad. The peripheral edge of the heat transfer pad is sandwiched between the reflection plate and the mounting bracket in close contact with the reflection plate and the mounting bracket, and the heat radiation fin of the LED lamp Is in contact with the heat transfer pad.
(2) The lamp unit according to (1) , wherein the heat transfer pad is configured by stacking a plurality of aluminum foils.
(3) The lamp unit according to (1) or (2) , wherein the heat transfer pad is in contact with the mounting bracket also in the periphery of the central portion in addition to the peripheral portion.
(4) In any one of (1) to (3) , the heat transfer pad has a folded portion at a peripheral portion, and the folded portion is fixed to the reflecting plate by the mounting bracket. The lamp unit described.
(5) A substantially bowl-shaped reflector, a front lens covering the front surface of the reflector, a socket attached to the center of the reflector via a fitting, and a heat transfer pad attached to the fitting And an LED lamp provided with an LED on the front surface of a main body provided with a plug screwed into the socket and a heat radiating fin, and a peripheral portion of the heat transfer pad between the reflector and the mounting bracket. The heat dissipation fin of the LED lamp is in contact with the heat transfer pad, the heat transfer pad has a folded portion at a peripheral edge, and the folded portion is A lamp unit that is fixed to a reflector.
(6) A signal lamp device in which the lamp unit according to any one of (1) to (5) is housed in a lamp box.

  According to the present invention, it is possible to provide an LED lamp or the like that can be used in a lamp unit having the same shape as a conventional one and that has a higher heat dissipation efficiency.

The perspective view of the LED lamp 1 which concerns on this invention. The enlarged perspective view of A section of LED lamp 1 concerning the present invention (A) Sectional drawing of the LED lamp 1 which concerns on this invention, (B) A partial enlarged view of (a). (A) Sectional drawing of the LED lamp 1a which concerns on this invention, (B) A partial enlarged view of (a). The exploded perspective view of LED lamp 1, the heat-transfer pad 43, the socket 33, etc. FIG. The exploded side view of LED lamp 1, the heat-transfer pad 43, the socket 33, etc. FIG. (A) Cross section of heat transfer pad 43, (b) Assembly cross section of LED lamp 1, heat transfer pad 43, socket 33, and the like. The assembly drawing of the lamp unit 41. FIG. The perspective view of the lamp unit 41 after an assembly. Sectional drawing of the lamp unit 41. FIG. The enlarged view of the heat transfer pad 43 periphery which illustrates the heat flow by heat conduction. (A) LED voltage-current characteristics, (b) LED ambient temperature-allowable forward current characteristics. Transient response model of LED lamp heat generation and temperature. The measurement result of the board | substrate part temperature rise of Example 1, 2 and the comparative example 1. FIG. (A) The perspective view of the traffic signal lamp for vehicles, (b) B-B 'sectional drawing of (a). Sectional drawing of the conventional LED lamp 103. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a perspective view showing an LED lamp 1 according to the present invention, FIG. 2 is an enlarged perspective view of a portion A in FIG. 1, and FIG. 3 (a) is a cross-sectional view of the LED lamp 1. 3 (b) is an enlarged view of part A of FIG. 3 (a), FIG. 4 (a) is a sectional view of the LED lamp 1a, and FIG. 4 (b) is an enlarged view of part A of FIG. 4 (a). is there.

  The LED lamp 1 is provided on an LED substrate 5 to which the LED 3 is attached, a room portion 9 that is provided in the center of the back surface of the LED substrate 5 and stores a power supply circuit 7 that supplies power to the LED 3, and a back surface of the LED substrate 5. The heat dissipating fins 11 are provided, the globe 13 is provided on the front surface of the LED substrate 5 so as to cover the LEDs 3, and the plug 15 is provided at the tip of the room portion 9. The globe 13 is provided with a ventilation portion 17 through which cooling air can flow into the globe 13.

  The LED substrate 5 is a disk-shaped aluminum plate, and the power supply circuit 7 converts the alternating voltage supplied from the plug 15 into direct current, adjusts it to become the operating voltage of the LED 3, and applies it to the LED 3. The room portion 9 is a hollow aluminum cylindrical body that houses the power supply circuit 7, and the heat radiating fins 11 are cooling metal plates that extend in a vertical direction from the back surface of the LED substrate 5 and are arranged in large numbers. Moreover, the outer part of the room part 9 also radiates heat to the air as a radiator. In addition, you may use materials other than aluminum for the LED board 5, the room part 9, and the radiation fin 11. FIG. The plug 15 is screwed into a socket 33 to be described later, and transmits power supplied from the socket 33 to the power supply circuit 7. The plug 15 has a shape compatible with a conventional signal light bulb. Further, the LED substrate 5, the power supply circuit 7, the chamber 9, the heat radiation fin 11, the plug 15 and the like are collectively referred to as an LED lamp body.

The ventilation portion 17 is a portion that is provided in the globe 13 and allows ventilation of cooling air into the globe 13. For example, in FIGS. 1 to 3, the ventilation portion 17 is provided by cutting out the peripheral portion of the globe 13 other than the leg portion 19 which is a member attached to the LED substrate 5 of the globe 13 and the LED substrate. It is a gap between 5. Through this ventilation part 17, the air which contacts the light emission surface part and board | substrate part of LED3 of a heat generation source is sent, heat is transmitted to air, and it thermally radiates and cools. In FIG. 1 to FIG. 3, a gap 19 is formed between the globe 13 and the LED substrate 5 by providing the leg 19 on the end surface of the globe 13 and the ventilation part 17 is formed. A through hole formed by hollowing out a part of the globe 13 may be used as the ventilation portion 17. Or it is good also as the ventilation part 17 by opening many through-holes 18 inside the glove | globe 13 of the outer peripheral part of the LED board 5 like the LED lamp 1a shown to Fig.4 (a), (b).
In addition, since the LED lamp 1 is installed in the sealed lamp unit 41, dust from outside air adheres to the LED 3 and hardly causes a failure. On the other hand, the general illumination light source may cause the LED lamp itself to be exposed to the outside air.

  A method for attaching the LED lamp 1 to the lamp unit 41 will be described with reference to FIGS. FIG. 5 is an exploded perspective view of the LED lamp 1, the heat transfer pad 43, the socket 33, and the like, and FIG. 6 is an exploded side view of the LED lamp 1, the heat transfer pad 43, the socket 33, and the like. ) Is a cross-sectional view of the heat transfer pad 43, FIG. 7B is an assembly cross-sectional view of the LED lamp 1, the heat transfer pad 43 and the socket 33, and FIG. 8 is an assembly view of the lamp unit 41. FIG. 9 is a perspective view of the lamp unit 41 after assembly.

As shown in FIGS. 5 and 6, first, the LED lamp 1 is screwed into the socket 33.
A mounting bracket 31 is provided on the socket 33. Further, the heat transfer pad 43 is sandwiched between the mounting bracket 31 and the LED lamp 1 and tightened.

  The mounting bracket 31 is a bracket that fits into a mounting hole 47 provided at the center of a substantially bowl-shaped reflecting plate 25 to be described later, and is fixed to the reflecting plate 25 by a connector 46 to be described later. The socket 33 is fixed to the mounting bracket 31 with screws or the like.

  The socket 33 has a metal fitting screwed into the plug 15 inside, and at the same time supplies the power supplied from the power cord 35 to the plug 15.

  As shown in FIG. 7A, the heat transfer pad 43 has a U-shaped cross section formed of a material having high thermal conductivity such as metal, and a through hole through which the chamber portion 9 passes is provided in the central portion. It is a thick disk-shaped member with high flexibility and elasticity. The periphery of the through hole in the central portion of the heat transfer pad 43 is swelled so as to be in close contact with the mounting bracket 31 to form a flexible contact portion 44, and the peripheral portion is formed on the cylindrical portion of the mounting hole 47 of the reflector 25. Folding portions 45 that engage with each other are provided.

  FIG. 7B is an assembled cross-sectional view after the LED lamp 1 is screwed into the socket 33 with the heat transfer pad 43 interposed therebetween. The heat transfer pad 43 contacts the back surface of the heat radiation fin 11 of the LED lamp 1. Further, the peripheral edge portion of the heat transfer pad 43 is sandwiched between the mounting bracket 31 and the reflection plate 25. Further, the folded-back portion 45 is pressed and adhered to the cylindrical portion of the mounting hole 47 of the reflector 25 by the mounting bracket 31. Further, the contact portion 44 of the heat transfer pad 43 is in close contact with the mounting bracket 31. That is, the heat transfer pad 43 thermally connects the radiating fin 11 and the mounting bracket 31 or the reflecting plate 25.

  The heat transfer pad 43 is made of a material having the same or close thermal expansion coefficient as that of the reflecting plate 25. Since the reflecting plate 25 is made of aluminum, the heat transfer pad 43 is preferably configured by laminating a plurality of aluminum foils. The heat transfer pad 43 formed by laminating a plurality of aluminum foils has high heat conductivity of aluminum and has a certain degree of flexibility, and is closely attached to the heat radiating fins 11, the reflecting plate 25, and the mounting bracket 31. The heat of the fin 11 can be efficiently transmitted to the reflecting plate 25. In addition, since the heat transfer pad 43 is pressed against the reflector 25 by the folded portion 45 and fixed, the heat transfer pad 43 does not fall off even when the LED lamp 1 is used for a signal lamp with a lot of vibration. The heat transfer pad 43 may be provided integrally with the heat radiating fins 11 and the LED substrate 5.

  Next, as shown in FIG. 8, the LED lamp 1 to which the socket 33, the mounting bracket 31, and the heat transfer pad 43 are attached is placed in the mounting hole 47 in the central hole portion of the reflector 25 having the front lens 23. Next, as shown in FIG. 9, the rear end portion of the mounting bracket 31 is fixed by the connector 46, the LED lamp 1 and the like are fixed to the reflecting plate 25, and the lamp unit 41 is made.

  FIG. 10 is a cross-sectional view showing a lamp unit 41 according to the present invention. The lamp unit 41 is attached to the substantially lamp-shaped reflecting plate 25, the front lens 23 that covers the front surface of the reflecting plate 25, the LED lamp 1 that is attached to the central portion of the reflecting plate 25 by the mounting bracket 31, and the LED lamp 1. A socket 33, a mounting bracket 31 for attaching the socket 33 to the reflection plate 25, and a power cord 35 extending from the socket 33 are provided.

  The reflecting plate 25 is a substantially bowl-shaped member for reflecting light emitted from the LED lamp 1 forward, and is usually made of metal. The front lens 23 is a colorless and transparent lens or a color lens. The material of the front lens 23 should be high in light transmittance and stable against ultraviolet rays and temperature changes so that it can withstand long-term use outdoors. .

  The mounting bracket 31 is a bracket that fits into a mounting hole 47 provided in the center of the reflecting plate 25 and is fixed to the reflecting plate 25. The socket 33 is integrated with the mounting bracket 31 with a screw or the like. The socket 33 has a metal fitting screwed into the plug 15 inside, and at the same time supplies the power supplied from the power cord 35 to the plug 15.

Next, the heat flow in the lamp unit 41 will be described. The heat generated in the LED lamp 1 is transmitted to the air through the heat dissipating fins 11 as shown in the air flow 27a in FIG. The air rises by transferring heat to the air inside.
When air that has reached a high temperature on the surface of the LED 3 comes out of the globe 13 from the upper part of the gap, the high-temperature rising air flow that has come out through the radiator on the back side creates a pressure-decreasing part. The effect of being sucked out can be expected.
That is, in the lamp unit 41, apart from the air flow in the conventional lamp unit 101, there is an air flow passing through the globe, so that heat can also be radiated from the front side surface of the LED substrate 5.

  The reason why the ventilation part 17 is provided without the globe 13 being in close contact with the LED substrate 5 and the light emitting surface part of the LED 3 is exposed to the airflow is that the traffic signal lamp is used only when the optical axis is almost horizontal. This is because the lamp unit itself has a hermetically sealed structure, and there is no fear of being affected by dust or condensation.

  The lamp unit 41 radiates heat by heat conduction from the radiating fins 11 to the reflecting plate 25 through the heat transfer pads 43 in addition to radiating heat by the air flow 27a. FIG. 11 is an enlarged view around the heat transfer pad 43 illustrating the heat flow 29a by heat conduction. The path through which heat can be extracted from the LED substrate 5 in the largest amount is a radiator composed of a large number of radiating fins 11 provided on the back surface of the LED substrate 5, so that these lamp units are further arranged behind the LED lamp 1. Applies to heat transfer path to components. In order to enhance the heat transfer function, a heat transfer pad 43 for heat conduction is brought into contact with the rear end of the radiator of the radiating fin 11. The heat transfer pad 43 is made of laminated aluminum foil or the like, and has a structure that allows necessary deformation by a flexible material. As a result, the lamp unit has a shape that fills the rear end space of the lamp unit and conducts heat well. The heat generated from the LED lamp 1 is transmitted from the heat radiation fin 11 to the reflection plate 25 and the mounting bracket 31 of the lamp unit 41 through the heat transfer pad 43. Furthermore, heat can be released from the reflector 25 and the mounting bracket 31 to the air having an external temperature outside the lamp unit 41.

  Here, the peripheral portion of the heat transfer pad 43 plays an important role in heat transfer. Since the lamp unit 41 has a structure in which the mounting bracket 31 in which the LED lamp 1 is assembled is fitted in the center of the reflecting plate 25, when the mounting bracket 31 is fitted and joined to the reflecting plate 25, the lamp unit 41 is interposed between both cylindrical portions. The thin peripheral portion of the heat transfer pad 43 can be sandwiched in the generated gap, and the two can be assembled in close contact with each other. Therefore, the gap is filled with the flexible peripheral portion of the heat transfer pad 43 that is flexible and has good heat conduction, and the heat is efficiently guided from the heat radiation fin 11 to the metal reflector 25 and the mounting bracket 31 of the lamp unit 41, New heat dissipation paths are added.

  The reflector 25 and the mounting bracket 31 that are in contact with the outside air function as a radiator, and in particular, the reflector 25 becomes a radiator having an extremely large surface area and has an effective cooling function. The large area of the heat transfer pad 43 in contact with the radiating fins 11 also functions as a flat plate radiator, and further increases the efficiency of heat dissipation.

That is, in this embodiment, since the globe 13 has the ventilation portion 17, there is a flow of air passing through the globe 13, heat can be radiated even on the front side surface of the LED substrate 5, and high heat dissipation performance is achieved.
In addition, in the present embodiment, since the heat transfer pad 43 is provided, the heat radiation fins of the LED lamp are connected from the heat source through a path in which a metal having good heat conduction is connected without using air as a medium for heat transfer. In addition, it is characterized in that a heat dissipation path for conducting heat is added to the lamp unit components, and it has high heat dissipation performance.

Hereinafter, the present invention will be specifically described using examples and comparative examples.
[Example 1]
An LED lamp in which twelve red light emitting LEDs are surface-mounted on a substrate portion and equipped with a globe, a heat radiating fin, and a driving power source portion is used. The total power consumption of this LED lamp is 9W. In the hemispherical globe, air can flow into the globe through a gap of 4 mm in height. Examine the effect of providing a gap. This LED lamp was attached to a lamp unit using a saddle-shaped reflector made of aluminum, to which a front plastic lens was attached.

[Example 2]
A heat transfer pad with stacked aluminum foil is provided so as to contact the heat radiating fin, and the periphery of the heat transfer pad is sandwiched between the mounting bracket and the reflector, and the contact portion around the through hole of the heat transfer pad is in close contact with the mounting bracket. Thus, a lamp unit was obtained in the same manner as in Example 1 except that the LED lamp was provided.

[Comparative Example 1]
A lamp unit was obtained in the same manner as in Example 1 except that a glove which was not provided with a ventilation part and was in a sealed state was used.

  A lamp unit equipped with these LED lamps was placed in a thermostatic chamber where the temperature could be controlled so that the optical axis of the lamp was horizontal, and the measurement was performed under the condition of a constant ambient temperature of 35 ° C. The temperature of the LED substrate was measured by a thermocouple fixed to the metal surface of the LED substrate of the lamp, and a transient response of the temperature increase of the LED substrate after lighting was obtained for three types of lamp units such as the examples.

[Temperature rise simulation and cooling effect evaluation method]
In a constant temperature environment, heat generation and temperature change due to internal power consumption are modeled for an LED lamp attached to a lamp unit of a vehicle signal lamp.
In this model, assuming that the entire LED lamp is integrated, the following physical quantities are defined.
Various quantities of LED lamps
Power consumption P [W]
Heat capacity C [J / K]
Heat dissipation coefficient H [J / K · s]
Let temperature T [K],
The ambient temperature of the outside air is T ₀ [K].
Here, the heat radiation coefficient H was defined as a coefficient representing the total heat radiation capability through all the heat radiation paths of the LED lamp. If the value of H is large, heat is quickly dissipated and dissipated, and the temperature rise is reduced by the effect of cooling, and the heat dissipating ability is high.
Using this model, the relational expression of heat in Δt time is expressed by the following equation, where ΔT is a temperature rise in Δt time.

  By arranging this, a differential equation with respect to time t of heat and temperature is obtained.

When the supply of a constant amount of electric power P is started at the environmental temperature T ₀ = constant and time t = 0, how the LED lamp temperature changes is solved by giving these conditions to the equation (2). It is requested from that. The transient response of temperature is given by equation (3), which is shown in FIG.

From the equation (3), the temperature appears as a value obtained by adding the temperature increase that increases with the time of the first term of the right side to the ambient temperature of the outside air of the second term of the right side. For this reason, since the ambient temperature allowed for the LED has an upper limit, it is confirmed that the amount of temperature change that can be increased to the upper limit temperature value is reduced when the LED is used at a high outdoor temperature. As described above, it is an object of the present invention to accelerate the cooling and reduce the temperature rise by improving the heat dissipation mechanism.
Consider how the response curve changes depending on the value of the heat dissipation coefficient H representing the heat dissipation capability. As the value of H, which is the first term on the right side of equation (3), increases, the time constant decreases and the response is accelerated. Further, H in the denominator of the coefficient of the first term on the right side determines a steady value for the temperature rise. That is, if the value of the heat dissipation coefficient H can be increased, the temperature rise can be reduced.
That is, since the effect of heat dissipation appears in the steady value where the temperature rises and can be easily read from the observation data, it can be used for the evaluation of the heat dissipation method using the level of the steady value for the temperature rise. Here, this method was used for comparative evaluation of experimental results.

[Measurement results of substrate part temperature rise in Examples 1 and 2 and Comparative Example 1]
The results of transient response experiments regarding the LED substrate temperature rise of the LED lamp are described in the same graph so that the comparison between Examples 1 and 2 and Comparative Example 1 can be performed, and are shown in FIG. The comparative evaluation of the heat dissipation capability of each method is performed by comparing the steady values for the temperature rise.

  In contrast to the conventional comparative example 1, in Example 1, the steady temperature is lowered by about 3 ° C. to increase the heat dissipating ability, but it is difficult to expand the heat dissipating area of the LED substrate surface, and the effect is limited. In Example 2, the steady temperature has been greatly reduced by nearly 8 ° C., and the ability can be further increased by increasing the adhesion of each element in the heat dissipation path.

  From the above-mentioned examples and comparative examples, the lighting operation of the LED traffic signal lamp provided with the cooling mechanism according to the present invention increases the reliability in the target traffic safety, and the technology maintains the performance in a high temperature environment, I am convinced that it is effective in prolonging the service life.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

1, 1a ......... LED lamp 3 ......... LED
5 ......... LED substrate 7 ......... Power supply circuit 9 ......... Room part 11 ......... Heat radiation 13 ......... Glove 15 ......... Plug 16 ......... Main body 17 ......... Ventilation part 18 ......... Penetration Hole 19 ......... Leg 23 ......... Front lens 25 ......... Reflector 27 ......... Air flow 29 ......... Heat flow 31 ......... Mounting bracket 33 ......... Socket 35 ......... Power cord 41 ......... Lamp unit 43 ......... Heat transfer pad 44 ......... Contact part 45 ......... Folded part 46 ......... Connector 47 ......... Mounting hole 51 ......... Signal lamp 53 ......... Lamp box 55 ... …… Signal light 101 ……… Lamp unit 103 ……… LED lamp

Claims (6)

A substantially bowl-shaped reflector,
A front lens covering the front surface of the reflector;
A socket attached to the central portion of the reflector via a mounting bracket;
A heat transfer pad attached to the mounting bracket;
An LED lamp provided with an LED on the front surface of a main body provided with a plug screwed into the socket and a radiation fin;
Comprising
For the heat transfer pad, a thin plate-like metal having wrinkles and having flexibility is used,
The peripheral portion of the heat transfer pad is sandwiched between the reflector and the mounting bracket in close contact with the reflector and the mounting bracket ,
The lamp unit, wherein the heat radiation fin of the LED lamp is in contact with the heat transfer pad. The lamp unit according to claim 1 , wherein the heat transfer pad is configured by laminating a plurality of aluminum foils. It said heat transfer pad, in addition to the peripheral portion, also in the peripheral central portion, the lamp unit according to claim 1 or 2, characterized in that in contact with the mounting bracket. The heat transfer pad has a folded portion at the peripheral edge,
The lamp unit according to any one of claims 1 to 3 , wherein the folded portion is fixed to the reflecting plate by the mounting bracket. A substantially bowl-shaped reflector,
A front lens covering the front surface of the reflector;
A socket attached to the central portion of the reflector via a mounting bracket;
A heat transfer pad attached to the mounting bracket;
An LED lamp provided with an LED on the front surface of a main body provided with a plug screwed into the socket and a radiation fin;
Comprising
The peripheral edge of the heat transfer pad is sandwiched between the reflector and the mounting bracket,
The heat dissipating fin of the LED lamp is in contact with the heat transfer pad;
The heat transfer pad has a folded portion at the peripheral edge,
The lamp unit, wherein the folded portion is fixed to the reflecting plate by the mounting bracket. A signal lamp device comprising: the lamp unit according to any one of claims 1 to 5 housed in a lamp box.

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