JP6811600B2 - Heat dissipation structure of vehicle lighting equipment - Google Patents

Description

The present invention relates to a heat dissipation structure of a vehicle lamp that cools a light source by promoting heat dissipation of a radiator installed in a duct by air flowing through the duct.

In recent years, semiconductor light emitting elements such as LEDs (light emitting diodes), which have advantages such as high luminous efficiency, high brightness, and power saving, have been used as light sources for vehicle lamps such as headlamps arranged on the left and right sides of the front of the vehicle. It's starting. While this type of semiconductor light emitting device has the above-mentioned advantages, it tends to become hot due to heat generation, and when the temperature rises, there is a problem that the luminous efficiency and the life are lowered.

Therefore, in a vehicle lamp that uses a semiconductor light emitting element as a light source, it is necessary to cool the semiconductor light emitting element by an appropriate means. Therefore, for example, Patent Document 1 proposes a heat dissipation structure shown in FIG.

That is, FIG. 9 is a vertical cross-sectional view showing the heat dissipation structure of the vehicle lighting equipment proposed in Patent Document 1. In the illustrated heat dissipation structure, the duct 103 is provided along the housing 102 of the vehicle lighting equipment 101 such as a headlamp. In addition to the arrangement, a configuration is adopted in which a heat exchange portion 105 such as a heat sink for radiating heat generated by the LED 104 as a light source is arranged in the duct 103.

In such a heat dissipation structure, the heat generated by the LED 104 when the vehicle lamp 101 is lit is the heat generated in the process in which the traveling wind generated by the traveling of the vehicle flows in from the intake port 103a of the duct 103 and is discharged from the exhaust port 103b. Since heat is dissipated by heat exchange with the traveling wind in the switching unit 105, the LED 104 is cooled and its luminous efficiency and life are prevented from being lowered.

However, in the above heat dissipation structure, when the traveling wind does not flow in the duct 103 because the vehicle is stopped, the heat exchange unit 105 cannot exert the heat exchange function and is in the engine room 106. Since hot air flows back from the exhaust port 103b into the duct 103 to heat the heat exchange section 105, there is a problem that the LED 104 cannot be effectively cooled.

Therefore, Patent Document 2 proposes a heat dissipation structure shown in FIG.

That is, FIG. 10 is a vertical cross-sectional view showing the heat dissipation structure of the vehicle lighting fixture proposed in Patent Document 2. In the illustrated heat dissipation structure, the duct 203 is provided along the housing 202 of the vehicle lighting fixture 201 such as a headlamp. A heat sink 205 for radiating heat generated by the two upper and lower lamps 204, which are light sources, is arranged in the duct 203, and each LED 204 and the heat sink 205 are connected by a heat conductive portion 206. Further, in addition to the intake port 203a and the exhaust port 203b, the forced exhaust port 203c is opened in the duct 203, and an exhaust fan 207 which is an exhaust means is arranged in the vicinity of the forced exhaust port 203c.

Further, the exhaust port 203b of the duct 203 is provided with an opening / closing portion 208 for opening / closing the exhaust port 203b, and the opening / closing portion 208 is connected to a rod 209a of the cylinder 209. A control unit 210 is connected to the cylinder 209 and the exhaust fan 207, and a vehicle speed sensor 211 that detects the speed of the vehicle equipped with the vehicle lamp 201 is connected to the control unit 210.

In such a heat dissipation structure, the flow velocity of the air flowing in the duct 203 is calculated based on the vehicle speed detected by the vehicle speed sensor 211, and when this flow velocity is slower than the fan average flow velocity, the control unit 210 controls the cylinder 209. As shown in the figure, the exhaust port 203b of the duct 203 is closed, and the exhaust fan 207 is driven to take in air from the intake port 203a of the duct 203 and to take in air from the forced exhaust port 203c. The air flow is induced in the duct 203 by forcibly discharging the air.

Therefore, even when the vehicle speed is slow or the vehicle is stopped, air flow is generated in the duct 203, so that heat dissipation of the heat sink 205 is promoted, and the heat sink 205 is connected to the heat sink 205 via the heat conductive portion 206. Each connected LED 204 is cooled and its temperature rise is suppressed.

Japanese Unexamined Patent Publication No. 2008-226843 Japanese Unexamined Patent Publication No. 2006-286395

However, in the heat dissipation structure of the vehicle lamp shown in FIG. 10 proposed in Patent Document 2, the exhaust fan 207 installed in the harsh environment of the engine room has high heat resistance, waterproofness, dustproofness, and vibration resistance. In addition to the need for properties, the control system for controlling the drive of the opening / closing unit 208 and the exhaust fan 207 according to the vehicle speed (flow velocity of air in the duct 203) becomes complicated, which causes a significant cost increase. There is.

Further, when the exhaust fan 207 fails, there is a problem that the cooling performance when the vehicle is running at low speed and when the vehicle is stopped is insufficient, which causes the temperature of the LED 204 to rise.

The present invention has been made in view of the above problems, and an object of the present invention is a vehicle lamp that can secure the required heat dissipation performance and suppress the temperature rise of the light source even when the vehicle is stopped by a simple configuration. The purpose is to provide a heat dissipation structure.

In order to achieve the above object, the invention according to claim 1 is a heat dissipation structure of a vehicle lamp provided with a light source and a radiator for radiating heat generated by the light source, and a vertical portion partially extending in the vertical direction. The radiator is internally provided in the vertical portion of the duct provided with the above, and the radiator is dissipated by the air flowing in from the intake port opened at one end of the duct and discharged from the exhaust port opened at the other end of the duct. In the heat dissipation structure of the vehicle lamp that promotes and cools the light source, the ventilation area S1 of the duct where the radiator is installed, the opening area S2 of the intake port of the duct, and the exhaust port of the duct. The opening area S3,
S2 ≧ (0.4 to 1.25) S1 ≧ S3
Set so that the relationship is established,
The exhaust port of the duct is opened between the front grille of the engine room of the vehicle and the condenser and the radiator .

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the light source and the radiator are thermally connected .

According to the invention according to claim 1, when the air in the duct is heated by the radiator having a high temperature when the vehicle is stopped, the vertical portion of the duct rises because the density of the heated air decreases. The flow of air is induced, and the low temperature outside air is sucked into the duct from the intake port and discharged from the exhaust port, so that the air flow is generated in the duct. Then, since the heat dissipation of the radiator is promoted by the natural air cooling by the air flowing through the duct, the temperature rise of the light source is suppressed. Since such an effect can be obtained by a simple configuration without requiring a separate device such as a fan, a place where a radiator of the duct is installed in a place where a significant cost increase and structural complexity are not caused. As a result of measuring the heat dissipation performance by changing the ratio (exhaust opening ratio) S3 / S1 of the opening area S3 of the exhaust port of the duct to the ventilation area S1, heat is dissipated when S3 / S1 = 1.0 (S3 = S1). It was confirmed that the performance was the highest, and the heat dissipation performance gradually decreased as the deviation from S3 / S1 = 1.0. Then, it was clarified that the heat dissipation performance without any problem in practical use can be actually obtained in the range of S3 / S1 = 0.4 to 1.25.

It was also confirmed that with respect to the opening area S2 of the intake port of the duct, the heat dissipation performance hardly changed when S2 = S1 and S2> S1. Therefore, the following magnitude relationship between S1, S2, and S3:
S2 ≧ (0.4 to 1.25) S1 ≧ S3
If is satisfied, the desired heat dissipation performance can be ensured and the temperature rise of the light source can be effectively suppressed.

In addition, even when the vehicle is stopped, the temperature is relatively low and there is almost no wraparound of hot air to the front of the vehicle. Since the exhaust port of the duct is opened between the front grille in the engine room and the condenser and radiator, the hot air is ducted. There is no inflow from the exhaust port of the duct and backflow in the duct. Therefore, the heat dissipation performance of the radiator is not impaired by the hot air, the heat dissipation of the radiator is promoted by natural air cooling, and the temperature rise of the light source is effectively suppressed.

It is a half-cut front view of a vehicle. It is a perspective view which shows the heat dissipation structure of the vehicle lamp which concerns on this invention. It is a plan sectional view which shows the heat dissipation structure of the vehicle lamp which concerns on this invention. It is a front view which shows the heat dissipation structure of the vehicle lamp which concerns on this invention. It is a schematic cross-sectional view of the duct in the heat dissipation structure of the vehicle lamp according to this invention. It is a figure which shows the relationship between the exhaust aperture ratio and thermal resistance in the heat dissipation structure of the vehicle lamp which concerns on this invention. It is a schematic cross-sectional view of the duct in the heat dissipation structure of the vehicle lamp according to another embodiment of the present invention. (A) and (b) are diagrams showing the development status of the velocity boundary layer and the temperature boundary layer between two heat radiation fins having different lengths, respectively. It is a vertical cross-sectional view which shows the heat dissipation structure of the vehicle lamp which proposed in Patent Document 1. FIG. It is a vertical cross-sectional view which shows the heat dissipation structure of the vehicle lamp which proposed in Patent Document 2.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a half-cut front view of the vehicle, and vehicle lamps 1 used as headlamps (only the one on the left side is shown in FIG. 1) are arranged on the front left and right sides of the illustrated vehicle 20. A louver-shaped front grill 21 for taking in outside air (running wind) is arranged in an engine room (not shown) in the central portion of the front surface of the vehicle lamp 1, and a front bumper 22 is arranged below the louver-shaped front grill 21. Are arranged horizontally in the vehicle width direction. In FIG. 1, 23 is a bonnet covering the upper part of the engine room, 24 is a windshield, 25 is left and right front wheels (only one is shown in FIG. 1), and 26 is left and right side mirrors.

Here, although not shown, an engine is mounted in the engine room of the vehicle 20, and an air conditioner condenser, a radiator, and a radiator fan are sequentially arranged in front of the engine in front of the engine. The front grill 21 is arranged, and the left and right vehicle lamps 1 are arranged.

By the way, when the outside air temperature is, for example, 40 ° C. when the vehicle 20 is stopped, the temperature in the engine room is about 70 ° C. to 100 ° C. Then, the hot air generated by the heat generated by the engine and the drive of the radiator fan is discharged from the engine room to the outside of the vehicle mainly through the bottom of the vehicle body and the vicinity of the tire house.

Next, the heat dissipation structure of the vehicle lamp 1 according to the present invention will be described below with reference to FIGS. 2 to 5.

FIG. 2 is a perspective view showing a heat dissipation structure of a vehicle lamp according to the present invention, FIG. 3 is a plan sectional view showing the heat dissipation structure, FIG. 4 is a front view showing the heat dissipation structure, and FIG. 5 is a duct in the heat dissipation structure. It is a schematic cross-sectional view. In the following, the heat dissipation structure of the vehicle lamp 1 on one side (left side) will be illustrated and described, but since the heat dissipation structure of the vehicle lamp on the other side (right side) is the same, the illustration and description thereof will be omitted. To do.

As shown in FIG. 3, vehicle lamps 1 used as headlamps are arranged side by side in the lighting chamber 4 defined by a transparent outer lens 3 covering the housing 2 and its front opening. It is configured to accommodate three lamp modules 5, three semiconductor light emitting elements 6 as light sources, an extension 7, and the like. Here, the three semiconductor light emitting elements 6 are arranged inside the vehicle of the housing 2 (on the right side in FIG. 3) at appropriate intervals along the vehicle front-rear direction (vertical direction in FIG. 3), and each semiconductor light emitting element 6 is arranged. Is connected to each lamp module 5 via a transmission fiber 8. Further, each lamp module 5 includes a phosphor 9 and a lens 10 for controlling light distribution. When the vehicle lamp 1 used as a headlamp emits white light, a blue LED is used for each semiconductor element 6, and a yellow phosphor is used for each phosphor 9.

By the way, as shown in FIGS. 2 to 4, a heat sink 11 as a radiator arranged outside the housing 2 is incorporated in the side wall of the housing 2 inside the vehicle. As shown in FIG. 3, the heat sink 11 is composed of a flat plate-shaped base 11a incorporated in the side wall of the housing 2 and a plurality of heat radiating fins 11b vertically erected from the base 11a toward the inside of the vehicle. Has been done. Here, as shown in FIG. 5, the plurality of heat radiation fins 11b are thin plate-shaped members long in the vertical direction, and these are arranged in the vehicle front-rear direction (appropriately spaced along the vertical direction in FIG. 3). The heat sink 11 is made of an aluminum alloy or a magnesium alloy having high thermal conductivity.

Here, as shown in FIG. 3, a total of three substrates 12 on which each semiconductor light emitting element 6 is mounted are attached to a flat plate-shaped heat radiating base 13 having high thermal conductivity, and the heat radiating base 13 is a heat sink 11. It is attached in close contact with the base 11a of the above.

A duct 14 that bends in a horizontal U shape in front view is arranged in the engine room of the vehicle 20, and the duct 14 has a substantially horizontal intake portion 14A and a housing 2 as shown in FIG. It is composed of a heat radiating portion 14B that stands vertically along the inner side wall of the vehicle and an exhaust portion 14C that extends diagonally upward from the radiating portion 14B toward the inside of the vehicle.

Here, as shown in FIG. 1, one end of the intake portion 14A of the duct 14 is opened to the front surface (a part of the front grill 21) of the vehicle 20 as an intake port 14a, and one end (upper end) of the exhaust portion 14C. Is open as an exhaust port 14b between the front grille in the engine room (not shown) and the condenser and the radiator. The heat sink 11 is internally provided in the heat radiating portion 14B that stands vertically in the duct 14.

Thus, in the present embodiment, the heat dissipation structure is composed of the heat sink 11, the heat dissipation base 13, and the duct 14, but when the vehicle 20 travels at night or the like, a current is applied to each semiconductor light emitting element 4 of the vehicle lamp 1. When each of them is supplied, each semiconductor light emitting element 6 emits light, and the blue light is transmitted to each lamp module 5 via each transmission fiber 8 and becomes white light by passing through the yellow phosphor 9. Will be converted. Then, the white light passes through the lens 10 and the light distribution is controlled, and then passes through the transparent outer lens 3 and is emitted to the front of the vehicle 20. Therefore, the vehicle lamp 1 functions as a headlamp. Fulfill.

Then, when each of the semiconductor light emitting elements 6 emits light as described above, each semiconductor light emitting element 6 generates heat, but the heat is conducted to the heat sink 11 via the substrate 12 and the heat dissipation base 13, and the plurality of the heat sinks 11 are present. Heat is dissipated from the heat sink fins 11b. When the vehicle 20 is traveling, the traveling wind flows into the duct 14 from the intake port 14a of the duct 14, and is pulled by the negative pressure generated by the operation of the radiator fan toward the exhaust port 14b in the duct 14. In the process, the air is forcibly cooled in each semiconductor light emitting element 6 in order to promote heat dissipation of the heat sink 11 by heat exchange with the heat sink 11 installed in the heat radiating portion 14B of the duct 14. The temperature rise is suppressed, and the light emission efficiency and life of each semiconductor light emitting element 6 are prevented from being lowered.

Further, when the vehicle 20 is stopped, the air around the high temperature heat sink 11 installed in the heat radiating portion 14B of the duct 14 is heated, and the density of the air becomes small, so that the radiating portion 14B of the duct 14 is used. An ascending air flow is induced, and the low temperature outside air is sucked into the duct 14 from the intake port 14a and discharged from the exhaust port 14b by being induced by this air flow. Therefore, the vehicle 20 is inside the duct 14. The same air flow as when traveling is generated. Then, since the heat dissipation of the heat sink 11 is promoted by the natural air cooling by the air flowing in the duct 14, the temperature rise of each semiconductor light emitting element 6 is suppressed.

When the radiator fan operates when the vehicle 20 is stopped, air flows through the duct 14 toward the exhaust port 14b due to the negative pressure generated by the operation of the radiator fan. In the process, the air flows. Heat dissipation of the heat sink 11 is promoted by heat exchange with the heat sink 11 provided inside the heat radiating portion 14B of the duct 14.

Then, in the present embodiment, the duct 14 is located between the front grille in the engine room and the condenser and the radiator in the engine room where the temperature is relatively low even when the vehicle 20 is stopped and the hot air hardly wraps around to the front of the vehicle 20. Since the exhaust port 14b is opened, hot air does not flow in from the exhaust port 14b of the duct 14 and flow back into the duct 14. Therefore, the heat dissipation performance of the heat sink 11 is not hindered by the hot air, and the heat dissipation of the heat sink 11 is promoted by natural air cooling, and the temperature rise of each semiconductor light emitting element 6 is effectively suppressed.

Therefore, since the above effects can be obtained by a simple configuration without requiring a separate device such as a fan, the heat dissipation structure does not cause a significant cost increase or complicated structure.

By the way, the ratio of the opening area S3 of the exhaust port 14b of the duct 14 to the ventilation area of the heat radiating portion 14B of the duct 14 (the area obtained by subtracting the cross-sectional area of the heat radiating fins 11b from the cross-sectional area of the heat radiating portion 14B) (exhaust opening ratio) S3. The result of measuring the heat dissipation performance by changing / S1 is shown in FIG. Here, the thermal resistance R (° C./W) was used as an index indicating the heat dissipation performance.

As shown in FIG. 6, the heat dissipation performance (thermal resistance R) is S3 / S1 = 1.0 (S3 = S1), that is, the ventilation area S1 of the heat dissipation portion 14B of the duct 14 and the opening area S3 of the exhaust port 14b. It was confirmed that the heat dissipation performance was the highest when they were equal, and the heat dissipation performance gradually decreased as S3 / S1 deviated from 1.0. In S3 / S1 <1.0, since the exhaust port 14b of the duct 14 is narrowed down, the amount of air flowing in the duct 14 is reduced, and the heat dissipation performance of the heat sink 11 is lowered. On the contrary, when S3 / S1> 1.0, since the exhaust port 14b of the duct 14 is wide, the air near the exhaust port 14b flows back into the duct 14, and the heat dissipation performance of the heat sink 11 deteriorates.

Generally, when mounting parts or units on a vehicle, miniaturization of these parts or units is required. Therefore, the size of the exhaust port 14b of the duct 14 cannot be sufficiently secured, and the opening area S3 tends to be small. Therefore, it is desirable to set the exhaust aperture ratio S3 / S1 to 0.4 to 1.0 based on the ventilation area S1 of the heat radiating portion 14B of the duct 14. However, even when the flow velocity of air in the duct 14 is slow as in natural air cooling, the flow velocity of air becomes even slower due to the pressure loss due to the length of the duct 14 and bending R, etc. In such a case, the outside air Since the backflow phenomenon of the above does not occur, the exhaust aperture ratio S3 / S1 can be set in the range of 0.4 to 1.25.

It was also confirmed that with respect to the opening area S2 of the intake port 14a of the duct 14, the heat dissipation performance hardly changes when S2 = S1 and S2> S1. Therefore, the following magnitude relationship between S1, S2, and S3:
S2 ≧ (0.4 to 1.25) S1 ≧ S3
If is satisfied, the heat sink 11 can secure the desired heat dissipation performance, and the temperature rise of each semiconductor light emitting element 6 can be effectively suppressed.

By the way, in the present embodiment, S1 and S3 have the opening area of the intake port 14a and the opening area of the exhaust port 14b, respectively, but when held, the intake portion 14A and the exhaust portion 14C of the 14 are connected to the intake port 14a and the exhaust port 14b. If there is a place with a small ventilation area, the minimum ventilation area is S1 and S2. Further, when the ventilation area of the heat radiating portion 14B of the duct 14 is not constant depending on the portion, the minimum ventilation area of the heat radiating portion 14B is set to S2.

In the present embodiment, the intake port 14a of the duct 14 is opened on the front surface of the vehicle 20 (a part of the front grill 21), but the opening position of the intake port 14a is arbitrary and is on the front surface of the vehicle 20. May be opened forward or downward in the lower part of the front end in the engine room without opening.

By the way, depending on the vehicle, the size of the vehicle lighting equipment is limited, but in such a vehicle lighting equipment heat dissipation structure, as shown in FIG. 7, a heat sink 11 installed internally in the heat dissipation portion 14B'of the duct 14'. The width of the'is not large, and the heat sink 1'may be vertically long.

Here, assuming that the vertical length of the heat radiating fin 11b of the heat sink 11 shown in FIG. 5 is h1 as shown in FIG. 8A, the vertical length of the heat radiating fin 11b'of the heat sink 11 shown in FIG. H2 (see FIG. 8B) is longer than h1 (h2> h1). The heat radiation fins 11b and 11b are generated by the air flowing between the two short heat radiation fins 11b shown in FIG. 8 (a) and between the two long heat radiation fins 11b'shown in FIG. 8 (b). From the tip (lower end) of', the velocity boundary layer and the temperature boundary layer develop along the air flow direction (upper).

Between the two heat-dissipating fins 11b having a short length shown in FIG. 8A, the heat-dissipating performance of the heat-dissipating fins 11b does not significantly deteriorate because the temperature boundary layer having a low heat transfer coefficient is not sufficiently developed. Between the two long heat radiating fins 11b'shown in FIG. 8B, there is a region where the temperature boundary layer develops and overlaps with each other, so that the heat radiating performance of the heat radiating fins 11b'is greatly deteriorated. .. Therefore, the distance between the two long heat radiation fins 11b'shown in FIG. 8 (b) is larger than the distance between the two short heat radiation fins 11b shown in FIG. 8 (a). It is necessary to set so that the temperature boundary layers do not overlap in the passage between the two long heat radiation fins 11b'. Incidentally, the horizontally long heat sink 11 shown in FIG. 5 is provided with nine heat radiation fins 11b, and the vertically long heat sink 11'shown in FIG. 7 is provided with five heat radiation fins 11b'.

In the above embodiment, the heat sink used has a plate type fin shape, but a pin type other than the plate type and a heat sink having an arbitrary fin shape such as a sword-shaped mountain or a bellows shape should be used. Can be done.

Further, in the above embodiment, the semiconductor light emitting element which is the heat source and the lamp module are connected via the transmission fiber, but the semiconductor light emitting element and the lamp module are integrated to heat the heat pipe or the like. A configuration that is thermally connected to the heat sink base by means of transportation can also be used. Then, because of the aiming adjustment mechanism, the heat sink may be connected to the housing via a rubber gasket or the like so that the heat sink can move within a certain range.

Further, although the embodiment in which the present invention is applied to the heat dissipation structure of a vehicle lamp used as a headlamp has been described above, the present invention is limited to a gasoline vehicle equipped with an engine as vehicle driving energy. Of course, it can also be applied to a vehicle using electricity, hydrogen fuel, or the like, and can also be applied to a heat dissipation structure of any vehicle lamp other than a headlamp. Further, in the present embodiment, the blue LED is used as the semiconductor light emitting element, but other semiconductor light emitting elements such as LEDs and lasers other than the blue LED can be used as the light source.

1 Vehicle lighting equipment 2 Housing 3 Outer lens 4 Lighting room 5 Lamp module 6 Semiconductor light emitting element (light source)
7 Extension 8 Transmission fiber 9 Fluorescent material 10 Lens 11 Heat sink (heat sink)
11a Heat sink base 11b Heat sink heat dissipation fin 12 Board 13 Heat dissipation base 14 Duct 14A Duct intake part 14B Duct heat dissipation part (vertical part)
14C Duct exhaust 14a Duct intake 14b Duct exhaust 20 Vehicle 21 Front grill 22 Front bumper 23 Bonnet 24 Windshield 25 Front wheel 26 Side mirror S1 Duct heat dissipation area Ventilation area S2 Duct intake opening area S3 Opening area of duct exhaust port

Claims (2)

The radiator is internally provided in the vertical portion of a duct having a light source and a radiator for radiating heat generated by the light source and having a vertical portion extending in the vertical direction. , A heat dissipation structure of a vehicle lamp that cools the light source by promoting heat dissipation of the radiator by air flowing in from an intake port opened at one end of the duct and discharged from an exhaust port opening at the other end of the duct. In
The ventilation area S1 of the duct where the radiator is installed, the opening area S2 of the intake port of the duct, and the opening area S3 of the exhaust port of the duct.
S2 ≧ (0.4 to 1.25) S1 ≧ S3
Set so that the relationship is established,
A heat-dissipating structure for a vehicle lamp, characterized in that the exhaust port of the duct is opened between the front grille of the engine room of the vehicle and a condenser and a radiator .
The heat radiating structure for a vehicle lamp according to claim 1, wherein the light source and the radiator are thermally connected .

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