Background to the Invention
[0001] Some vehicular headlamps have a projector-type lamp unit provided therein. The projector-type
lamp unit generally includes a light source, a projection lens, and a reflector that
reflects light from the light source forward toward the projection lens. The vehicular
headlamp forms a lamp chamber sealed by attaching a cover in front of a lamp body,
and the projector-type lamp unit is provided inside the lamp chamber.
[0002] An extension for covering and hiding portions other than the projection lens of the
projector-type lamp unit, a gap between the lamp body and the projector-type lamp
unit, and the like is provided inside the vehicular headlamp having the projector-type
lamp unit provided therein. The extension has an opening section for releasing light
from the projector-type lamp unit externally. Thus, the lamp chamber is divided into
a space (front chamber) between the cover and the extension and a space (rear chamber)
between the extension and the lamp body with the extension being the boundary.
[0003] Since, in the projector-type lamp unit, the opening of the reflector formed of an
approximate ellipsoidal curved surface is covered by the projection lens and the light
source is heated in a space within the unit not having a large opening, high-temperature
air easily flows out externally. The high-temperature air flown out flows between
the extension and the lamp body and becomes an ascending current to generate a convective
flow.
[0004] For example, in a vehicular headlamp in which a low-beam unit is arranged above a
high-beam unit, the low-beam unit is used with high frequency in a normal usage state,
and the temperature of a front surface cover on a side of the high-beam unit used
with low frequency hardly increases. Therefore, in normal usage, moisture generated
in a low-beam radiation surface of the front surface cover temporarily rises due to
the convective flow, and then flows below to a low temperature section side to thereby
stagnate in a lamp bottom section.
[0005] Therefore, dew is formed on an inner surface of the front surface cover on the high-beam
unit side to cause a phenomenon of fogging.
[0006] In order to prevent such formation of dew, an automobile lamp disclosed in, for example,
Japanese Patent Application Publication No.
JP-A-2004-119198 prevents the dew from being formed particularly on the front surface cover by providing
a current plate to change the direction and the flow speed of the convective flow
in the lamp.
[0007] In recent years, along with the increase in size and increase of slanted shapes in
vehicular headlamps, a lamp shape in which a lamp chamber end section extends apart
from a light source is required. Due to such slanted shape, a lamp chamber has a lamp
chamber end section 500, such as that shown in FIG. 6, extending laterally with respect
to a projector-type lamp unit provided therein and rearward of a vehicle.
[0008] The lamp chamber end section 500 is formed with a flat space 505 having a thin thickness
between a lamp body 501 and a front surface cover (cover) 503. Between the front surface
cover 503 and the lamp body 501, an extension 507 is arranged to divide the flat space
in the thickness direction.
[0009] Since high-temperature air flows out between the extension 507 and the lamp body
501 from the projector-type lamp unit, an air flow 509 of high-temperature air that
turns at a terminal end section 507a of the extension 507 to be blown out toward the
front surface cover 503 easily occurs in the lamp chamber end section 500. When the
high-temperature air flow 509 occurs, dew 511 is formed on the inner surface of the
front surface cover, which is apart from a light source and is cooled by external
air. This phenomenon of dew formation became more apparent as the distance from the
light source to the lamp chamber end section 500 increased. With the structure in
which the high-beam unit and the low-beam unit are not arranged in the up-down direction
as in the example of the related art described above, i.e., a structure of horizontal
arrangement, the dew formation in the lamp chamber end section also occurred in the
same manner.
[0010] The present invention has been made in view of the situation described above, and
has an object of providing a vehicular headlamp in which an air flow turning at a
terminal end section of an extension from between the extension and a lamp body to
blow on a cover can be blocked in a rear section of a lamp chamber end section to
prevent formation of dew at the cover in the rear section of the lamp chamber end
section.
Summary of the Invention
[0011] The above-described object of the present invention is achieved by a vehicular headlamp
including, in a lamp chamber formed of a lamp body and a cover, a projector-type lamp
unit having a light source, a projection lens, and a reflector that reflects light
from the light source forward toward the projection lens, and an extension that covers
a gap between the lamp body and the projector-type lamp unit, wherein the lamp chamber
has a lamp chamber end section extending laterally with respect to the projector-type
lamp unit and rearward of a vehicle, and an air flow blocking section that blocks
air flowing rearward of the lamp chamber end section from the projector-type lamp
unit is provided between the extension and the lamp body in a front section of the
lamp chamber end section.
[0012] With the vehicular headlamp having the configuration described above, high-temperature
air leaking from the projector-type lamp unit is stopped by the air flow blocking
section from flowing from a space between the extension and the lamp body toward the
rear section of the lamp chamber end section. Accordingly, the high-temperature air
does not flow from the front section of the lamp chamber end section into the rear
section thereof, whereby the cover is not blown by the high-temperature air that has
flown in and turned at a terminal end section of the extension from between the extension
and the lamp body in the rear section of the lamp chamber end section.
[0013] Further in the vehicular headlamp having the configuration described above, it is
preferable that the air flow blocking section be formed by causing a portion of the
extension or the lamp body to protrude in a direction to reduce the gap between the
lamp body and the extension.
[0014] With the vehicular headlamp having such configuration, the air flow blocking section
is formed integrally with the lamp body or the extension, whereby formation becomes
easy. The gap between the lamp body and the extension can be closed simultaneously
with the extension being assembled to the lamp body, and extra assembly work of attaching
an exclusive member for a blocking high-temperature air flow is not necessary.
[0015] Further in the vehicular headlamp having the configuration described above, it is
preferable that a lower section of the extension below the projector-type lamp unit
be provided with a ventilation opening section for causing air between the cover and
the extension to flow in between the extension and the lamp body.
[0016] With the vehicular headlamp having such configuration, an ascending current is formed
in the space between the extension and the lamp body due to heat of the projector-type
lamp unit, and air cooled by the cover to have a low temperature and high humidity
flows between the extension and the lamp body from the ventilation opening section,
thereby forming dew on a back surface of the extension and a surface of the lamp body.
Accordingly, formation of dew due to air having high temperature and humidity hardly
occurs on an inner surface of the cover in the lamp chamber end section.
Brief Description of the Drawings
[0017] A preferred embodiment of a vehicular headlamp according to the present invention
will be described below in detail with reference to the accompanying drawings, in
which:-
FIG. 1 is a horizontal sectional view of a vehicular headlamp according to the present
invention.
FIG. 2 is a front view of the vehicular headlamp shown in FIG. 1.
FIG. 3 is a view on arrow along III-III of FIG. 2.
FIG. 4 is a perspective view of the vehicular headlamp shown in FIG. 1 when seen from
the front left-upward direction.
FIG. 5 is an enlarged sectional view of a lamp chamber end section of the vehicular
headlamp shown in FIG. 1.
FIG. 6 is an enlarged sectional view of a lamp chamber end section of a vehicular
headlamp of the related art.
Detailed Description
[0018] FIG. 1 is a horizontal sectional view of the vehicular headlamp according to the
present invention, FIG. 2 is a front view of the vehicular headlamp shown in FIG.
1, FIG. 3 is a view on arrow along III-III of FIG. 2, FIG. 4 is a perspective view
of the vehicular headlamp shown in FIG. 1 when seen from the front left-upward direction,
and FIG. 5 is an enlarged sectional view of a lamp chamber end section of the vehicular
headlamp shown in FIG. 1.
[0019] As shown in FIG. 1, a vehicular headlamp 100 according to this embodiment is a lamp
arranged in a front right end section of a vehicle, and two lamp units 25 and 27 are
arranged to be adjacent to each other in the vehicle width direction to be stored
in a lamp chamber 22 formed of a lamp body 21 and a translucent front surface cover
(cover) 23 attached to a front end opening section thereof. In the vehicular headlamp
100, a low-beam distribution pattern is formed by lighting the lamp unit 25, and a
high-beam distribution pattern is formed by simultaneously lighting the lamp units
25 and 27.
[0020] The two lamp units 25 and 27 both have an optical axis extending in the vehicle front-rear
direction, and are supported to the lamp body 21 through aiming mechanisms 29 so as
to be capable of tilting in the up-down direction and the left-right direction. At
a stage where aiming adjustments by the aiming mechanisms 29 are completed, the optical
axis of the lamp unit 25 extends in a direction approximately 0.5 to 0.6o downward
with respect to the vehicle front-rear direction, while the optical axis of the lamp
unit 27 extends in the vehicle front-rear direction.
[0021] The front surface cover 23 is formed to curve rearward along the shape of the vehicle
on a right side corner section of a front end section of the vehicle from the inside
in the vehicle width direction to the outside in the vehicle width direction, and
to curve rearward from a lower end edge to an upper end edge thereof. Therefore, as
shown in FIG. 4, the two lamp units 25 and 27 are arranged such that the lamp unit
25 located on the outside in the vehicle width direction is displaced to the rearward
side to some degree with respect to the lamp unit 27 located on the inside in the
vehicle width direction.
[0022] In the lamp chamber 22, an extension 31 covering gaps among the lamp body 21 and
the two lamp units 25 and 27 is provided along the front surface cover 23. The extension
31 is formed with opening sections 31a and 31b encompassing projection lenses 39 and
51 of the respective lamp units 25 and 27 in the vicinity of front end sections thereof.
The opening sections 31 a and 31 b are openings for releasing light from the lamp
units 25 and 27 externally.
[0023] Next, the configurations of the respective lamp units 25 and 27 will be described.
First, the configuration of the lamp unit 25 will be described.
[0024] The lamp unit 25 is a projector-type lamp unit, and includes a light source bulb
33, a reflector 35, a lens holder 37, the projection lens 39, and a shade 41.
[0025] The projection lens 39 is configured as a planoconvex lens having a forward side
surface 39a as a curved convex surface and a rear end surface (rearward side surface)
39b as a flat surface, and a lens center axis is arranged on the optical axis. The
projection lens 39 projects an image on a focal plane including a rearward focal point
thereof forward as an inverted image. The forward side surface 39a of the projection
lens 39 emits light reaching the projection lens 39 via the reflector 35 to be approximately
parallel with the optical axis.
[0026] The lens holder 37 is formed to extend approximately in a cylinder shape step-tapered
forward from a front end opening section of the reflector 35, is fixedly supported
by the reflector 35 at a rear end section thereof, and fixedly supports the projection
lens 39 at a front end section thereof.
[0027] The light source bulb 33 is a discharge bulb such as a metal halide bulb with a discharge
light-emitting section as a light source, and the light source is configured as a
line segment light source extending in the center axis direction of the bulb. The
light source bulb 33 is inserted and secured to a rear end opening section of the
reflector 35 from the rearward side such that the light source is arranged on the
optical axis and provided rearward with respect to the rearward focal point of the
projection lens 39.
[0028] The reflector 35 has a reflective surface 35a that reflects light from the light
source forward toward the optical axis. The reflective surface 35a has a sectional
shape approximately in an elliptical shape, and the light from the light source is
reflected by the reflective surface 35a to approximately converge in the vicinity
of the rearward focal point of the projection lens 39 in a vertical sectional surface.
[0029] The reflector 35 is supported to the lamp body 21 through the aiming mechanisms 29
using aiming brackets 43 formed at four parts.
[0030] The shade 41 is fixedly supported by the lens holder 37 to be located approximately
in a lower half section in an inner section space of the lens holder 37. The shade
41 is formed such that an upper end edge thereof passes through the rearward focal
point of the projection lens 39, so that a part of reflected light from the reflective
surface 35a of the reflector 35 is blocked to remove a majority of upward light to
be emitted forward from the projection lens 39.
[0031] Next, the configuration of the lamp unit 27 will be described.
The lamp unit 27 also is a projector-type lamp unit in the same manner as the lamp
unit 25, and includes a light source bulb 45, a reflector 47, a lens holder 49, and
a projection lens 51.
[0032] The lamp unit 27 does not include the shade 41 as in the lamp unit 25, but other
configurations are approximately the same as in the case of the lamp unit 25. Note
that the shape of the reflective surface of the reflector 47 of the lamp unit 27 is
set such that the convergence position of light from the light source is slightly
closer to the rearward focal point of the projection lens 51 compared with that of
the reflector 35 of the lamp unit 25.
[0033] The lamp unit 27 also is supported to the lamp body 21 through aiming mechanisms
29 using aiming brackets 53 formed at four parts of the reflector 47.
[0034] As described above, the front surface cover 23 is formed to curve rearward along
the shape of the vehicle on the right side corner section of the front end section
of the vehicle from the inside in the vehicle width direction to the outside in the
vehicle width direction. Accordingly, as shown in FIGS. 1 to 4, the lamp chamber 22
includes a lamp chamber end section 55 extending laterally with respect to the lamp
unit 25 and rearward of the vehicle.
[0035] The lamp chamber 22 is divided into a space (front chamber) between the front surface
cover 23 and the extension 31 and a space (rear chamber) between the extension 31
and the lamp body 21 with the extension 31 being the boundary.
[0036] The lamp body 21 and the front surface cover 23 in the lamp chamber end section 55
are arranged to face each other with a flat space therebetween. An extended terminal
end section 31 c of the extension 31 is arranged approximately in a center section
of the flat space in the thickness direction, and the terminal end section 31c divides
the flat space in the thickness direction.
[0037] Between the extension 31 and the lamp body 21 in a front section 55a of the lamp
chamber end section 55, an air flow blocking section 57 is provided.
[0038] The air flow blocking section 57 is provided in the vicinity of the aiming bracket
43 securing the lamp unit 25, and extends for a predetermined length in the up-down
and left-right directions along the lamp body 21 and the extension 31.
[0039] The air flow blocking section 57 has one end bonded to the lamp body 21 and the other
end section arranged to contact the extension 31, so that air 63 (see FIG. 5) flowing
from the lamp units 25 and 27 to a rear section 55b of the lamp chamber end section
55 is blocked. At the same time, the displacement of the extension 31 is suppressed.
[0040] Note that the air flow blocking section 57 can be formed by, for example, causing
a portion of the extension 31 or the lamp body 21 to protrude in a direction to reduce
the gap between the lamp body 21 and the extension 31.
[0041] When the air flow blocking section 57 is formed integrally with the lamp body 21
or the extension 31 in this manner, formation becomes easy, the gap between the lamp
body 21 and the extension 31 can be closed simultaneously with the extension 31 being
assembled to the lamp body 21, and extra assembly work of attaching an exclusive member
for blocking a high-temperature air flow is not necessary.
[0042] As shown in FIGS. 2 to 4, a lower section 31 d of the extension 31 below the lamp
unit 25 is provided with a ventilation opening section 59 for causing air 67 (see
FIG. 3) between the front surface cover 23 and the extension 31 to flow in between
the extension 31 and the lamp body 21. Note that, when the vehicular headlamp 100
is attached to the vehicle, the ventilation opening section 59 is covered by, for
example, a bumper 61 as a part of the vehicle and cannot be seen from the front.
[0043] With the vehicular headlamp 100 of this embodiment, the high-temperature air 63 (see
FIG. 5) leaking from the lamp units 25 and 27 to flow from the space between the extension
31 and the lamp body 21 toward the rear section 55b of the lamp chamber end section
55 is stopped by the air flow blocking section 57.
[0044] Accordingly, the high-temperature air 63 does not flow into the rear section 55b
from the front section 55a of the lamp chamber end section 55, whereby the front surface
cover 23 is not blown by the high-temperature air 63 that has flown in and turned
at the terminal end section 31 c from between the terminal end section 31c of the
extension 31 and the lamp body 21 in the rear section 55b of the lamp chamber end
section 55.
[0045] In the space between the extension 31 and the lamp body 21 and the space between
the front surface cover 23 and the extension 31, an ascending current 65 (see FIG.
3) is formed due to heat from the opening sections 31 a and 31 b of the lamp units
25 and 27.
[0046] The air 67 cooled by the front surface cover 23 to have a low temperature and high
humidity flows between the extension 31 and the lamp body 21 from the ventilation
opening section 59, thereby forming dew on an inner surface and the like of the lamp
body 21 in the rear chamber. Accordingly, formation of dew due to air having high
temperature and humidity hardly occurs on an inner surface of the front surface cover
23 in the lamp chamber end section 55.
[0047] That is, with the vehicular headlamp 100 of this embodiment, the high-temperature
air 63 leaking from the lamp units 25 and 27 to flow from the space between the extension
31 and the lamp body 21 toward the rear section 55b of the lamp chamber end section
55 is stopped by the air flow blocking section 57, whereby the air flow 509 (see FIG.
6) can be prevented from turning at the terminal end section 31 c of the extension
31 from between extension 31 and the lamp body 21 in the rear section 55b of the lamp
chamber end section 55 to blow on the front surface cover 23, and the formation of
the dew 511 (see FIG. 6) on the inner surface of the front surface cover 23 in the
lamp chamber end section 55 can be prevented.
[0048] Note that the effect of the present invention is made apparent in a structure in
which the lamp chamber end section 55 is apart from the proximate lamp unit 25 by
140 mm or more. That is, when the lamp chamber end section 55 is apart from the lamp
unit 25 by 140 mm or more, heat from the light source bulb 33 is barely transmitted,
whereby air with humidity is cooled to easily form dew. In such a lamp, the high-temperature
air 63 can particularly be prevented from flowing into the lamp chamber end section
55, whereby an apparent effect of preventing the formation of dew is obtained.
[0049] In the embodiment described above, an example has been described for a case where
the two lamp units 25 and 27 are both projector-type lamp units. However, the same
effect as that described above is obtained as long as the vehicular headlamp according
to the present invention includes at least one projector-type lamp unit.