TECHNICAL FIELD
[0001] The present invention relates to a lamp unit and a ventilation method for a body
housing of a lamp.
BACKGROUND ART
[0002] Technologies for ventilation in lamps such as vehicle lamps have been conventionally
known.
[0003] For example, Patent Literature 1 describes a vehicle lamp including a lamp chamber
composed of a lamp body and a light-transmitting cover. In this vehicle lamp, a ventilation
hole is formed in at least one portion of the light-transmitting cover to allow communication
between the inside space and external space of the lamp chamber. In addition, a filter
with waterproof and moisture-diffusing properties is attached to cover the ventilation
hole.
CITATION LIST
Patent Literature
SUMMARY OF INVENTION
Technical Problem
[0005] The technique described in Patent Literature 1 leaves room for reexamination from
the viewpoint of preventing fogging inside a lamp or effectively removing fogging
that has occurred inside a lamp. In view of this, the present invention provides a
lamp unit that is advantageous for preventing fogging inside a lamp or effectively
removing fogging that has occurred inside a lamp.
Solution to Problem
[0006] The present invention provides a lamp unit including:
a body housing including: a light-transmitting member; a body wall joined to the light-transmitting
member to form a housing; and a first opening portion and a second opening portion
positioned in the body wall and each forming an opening communicating with an external
space of the housing;
a light source disposed inside the body housing; and
a pump having a gas discharge port connected to the first opening portion.
[0007] The present invention also provides a ventilation method for a body housing of a
lamp,
the lamp including a lamp unit,
the lamp unit including:
the body housing including: a light-transmitting member; a body wall joined to the
light-transmitting member to form a housing; and a first opening portion and a second
opening portion positioned in the body wall and each forming an opening communicating
with an external space of the housing;
a light source disposed inside the body housing;
a pump having a gas discharge port connected to the first opening portion; and
a ventilation member for ventilation between the body housing and the external space,
and
the ventilation method including:
allowing the pump to discharge a gas toward the body housing such that requirements
represented by the following expressions (IIa) and (IIb) are satisfied,


where p is a pressure [kPa] inside the body housing during operation of the pump,
t is a discharge time [s] of the pump, P is an air permeability coefficient [cm3/(Pa•s•cm2)] of the ventilation member, A is a permeable area [cm2] of the ventilation member, and V is a spatial volume [cm3] inside the lamp unit.
Advantageous Effects of Invention
[0008] The above lamp unit is advantageous for preventing fogging inside a lamp or effectively
removing fogging that has occurred inside a lamp.
BRIEF DESCRIPTION OF DRAWINGS
[0009]
FIG. 1 is a cross-sectional view schematically showing a lamp unit of the present
disclosure.
FIG. 2A schematically shows an example of the arrangement of opening portions in the
lamp unit shown in FIG. 1.
FIG. 2B schematically shows another example of the arrangement of the opening portions
in the lamp unit.
FIG. 3 is a cross-sectional view of an example of a ventilation member in the lamp
unit.
FIG. 4 is a cross-sectional view of another example of a ventilation member in the
lamp unit.
FIG. 5A is a photograph of the front of the headlamp of Chery Tiggo 8.
FIG. 5B is a photograph of the bottom of the headlamp shown in FIG. 5A.
FIG. 5C is a photograph of the rear of a lamp unit according to Example 1A.
FIG. 6A is a photograph of the front of the headlamp of GEELY Emgrand X7.
FIG. 6B is a photograph of the rear of the headlamp shown in FIG. 6A.
FIG. 6C is a photograph of the rear of a lamp unit according to Example 2A.
FIG. 7A is a photograph of the front of the headlamp of Ford Escape.
FIG. 7B is a photograph of the rear of the headlamp shown in FIG. 7A.
FIG. 7C is a photograph of the rear of a lamp unit according to Example 3A.
FIG. 8 is a graph showing, in evaluation of the ventilation performance of the lamp
units, the relationship between a time T required for fogging to be removed and the
value of 1000•p•t•P•A/V.
DESCRIPTION OF EMBODIMENTS
[0010] Embodiments of the present invention will be described with reference to the drawings.
The present invention is not limited to the following embodiments.
[0011] As shown in FIG. 1, a lamp unit 1a includes a body housing 10, a light source 13,
and a pump 15. The body housing 10 includes a light-transmitting member 11, a body
wall 12, a first opening portion 12a, and a second opening portion 12b. The body wall
12 is joined to the light-transmitting member 11 to form a housing. The first opening
portion 12a and the second opening portion 12b are positioned in the body wall 12
and each form an opening communicating with the external space of the housing. The
light source 13 is disposed inside the body housing 10. The pump 15 has a gas discharge
port 15a, and the gas discharge port 15a is connected to the first opening portion
12a. The gas discharge port 15a is connected to the first opening portion 12a, for
example, via a flow path member, such as a tube. The gas discharge port 15a may be
directly connected to the first opening portion 12a.
[0012] When moisture absorption occurs in a lamp, the air inside the lamp is warmed by solar
radiation on the lamp or by lighting of the lamp, causing the moisture to be released
into the air outside. When the inside of the lamp is cooled rapidly under this state,
condensation occurs inside the lamp, potentially causing the occurrence of fogging
on the inner surface of the light-transmitting member that is the member that transmits
light generated from the light source in the lamp. For example, events such as vehicle
washing and rainfall can rapidly cool the inside of a lamp. When a phenomenon occurs,
such as a large area of fogging occurring on the inner surface of the light-transmitting
member or prolonged fogging persisting on the inner surface of the light-transmitting
member, user dissatisfaction may increase. On the other hand, according to the lamp
unit 1a, for example, operation of the pump 15 sends air from the external space into
the inside of the housing of the lamp unit 1a through the first opening portion 12a.
In addition, moisture present inside the housing of the lamp unit 1a is directed to
the outside of the housing through the second opening portion 12b. Therefore, in the
lamp unit 1a, fogging is less likely to occur on the inner surface of the light-transmitting
member 11. Even if fogging occurs on the inner surface of the light-transmitting member
11, the fogging is likely to be effectively removed.
[0013] As shown in FIG. 1, the light-transmitting member 11 is disposed, for example, in
front of the light source 13 in the traveling direction of light generated from the
light source 13. In the lamp unit 1a, the light-transmitting member 11 transmits light
generated from the light source 13.
[0014] As shown in FIG. 1, in the lamp unit 1a, the body wall 12 is disposed, for example,
to cover the rear and lateral sides of the light source 13 with respect to the traveling
direction of light generated from the light source 13. In the lamp unit 1a, the body
wall 12 is joined to the light-transmitting member 11 in a state where the body wall
12 is in contact with the periphery of the light-transmitting member 11. The manner
of joining the body wall 12 and the light-transmitting member 11 to each other is
not limited to a particular manner. The body wall 12 and the light-transmitting member
11 are joined to each other, for example, by snap-fitting or screwing. The body wall
12 is composed of, for example, a non-light-transmitting member.
[0015] The light source 13 is not limited to a particular light source. The light source
13 may be a halogen lamp, an HID lamp, or an LED lamp.
[0016] As shown in FIG. 1, the lamp unit 1a includes, for example, a ventilation member
20. The ventilation member 20 is a member for ventilation between the body housing
10 and the external space of the body housing 10. The ventilation member 20 is provided
at the second opening portion 12b. The ventilation member 20 is, for example, attached
to a portion of the body wall 12 that abuts the second opening portion 12b such that
the ventilation member 20 covers the second opening portion 12b in a ventilatable
manner.
[0017] The ventilation member 20 is not limited to a particular member as long as the ventilation
member 20 allows ventilation between the body housing 10 and the external space of
the body housing 10. The ventilation member 20 is, for example, a gas-permeable member
that prevents the entry of foreign substances such as water and dust. The ventilation
member 20 may include a known gas-permeable membrane, or may include a porous body,
such as a woven fabric, a nonwoven fabric, or foam, a mesh, or a net.
[0018] The gas-permeable membrane may be a single-layer membrane or a multilayer membrane.
In the case where the gas-permeable membrane is a multilayer membrane, each layer
thereof can be one selected from the group consisting of a porous membrane, a nonwoven
fabric, a cloth, and a mesh. Desirably, the gas-permeable membrane may include: a
porous membrane and a nonwoven fabric; a porous membrane and at least one of a cloth
and a mesh; or plurality of nonwoven fabrics. The gas-permeable membrane is typically
composed of an organic polymer (resin). The material of the porous membrane is, for
example, a fluororesin. Examples of the fluororesin that can be used include polytetrafluoroethylene
(PTFE), polychlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymers,
and tetrafluoroethylene-ethylene copolymers. Examples of the materials of the nonwoven
fabric, the cloth, and the mesh include polyesters, such as polyethylene terephthalate,
polyolefins, such as polyethylene and polypropylene, nylons, aramids, and ethylene-vinyl
acetate copolymers.
[0019] The gas-permeable membrane includes, for example, an extended porous PTFE membrane.
In this case, the extended porous PTFE membrane may be layered on a gas-permeable
supporting member such as a nonwoven fabric.
[0020] The gas-permeable membrane may be subjected to a liquid-repellent treatment as necessary.
The liquid-repellent treatment is performed, for example, by forming, on the gas-permeable
membrane, a liquid-repellent coating film containing a fluorine surface modifier having
a perfluoroalkyl group. The formation of the liquid-repellent coating film is not
limited to a particular method, and is performed, for example, by coating a porous
resin membrane with a solution or dispersion of a fluorine surface modifier having
a perfluoroalkyl group by a method such as air spray coating, electrostatic spray
coating, dip coating, spin coating, roll coating, curtain flow coating, or impregnation.
Alternatively, electrodeposition coating or plasma polymerization may be employed
to form the liquid-repellent coating film.
[0021] The pump 15 is not limited to a particular pump as long as the pump 15 has the gas
discharge port 15a. The pump 15 has a maximum discharge pressure P
dis_max of, for example, 0.5 to 20 kPa. In this case, in the lamp unit 1a, fogging is less
likely to occur on the inner surface of the light-transmitting member 11. Even if
fogging occurs, the fogging is likely to be effectively removed without breakage of
the body housing 10 or the ventilation member 20. The maximum discharge pressure P
dis_max is desirably 10 kPa or less, more desirably 5 kPa or less, and even more desirably
4 kPa or less. The maximum discharge pressure P
dis_max can be measured, for example, with one end of a flow path member, such as a tube,
connected to the gas discharge port 15a and the other end of the flow path member
connected to the first opening portion 12a. A pressure gauge is disposed on the flow
path member, between the gas discharge port 15a and the first opening portion 12a,
allowing the maximum discharge pressure P
dis_max to be determined by reading the pressure indicated on the pressure gauge during operation
of the pump 15 at maximum output.
[0022] The arrangement of the first opening portion 12a and the second opening portion 12b
in the body wall 12 is not limited to a particular arrangement. As shown in FIG. 2A,
in plan view of a portion of the outer surface of the body wall 12 that forms the
rear of the lamp unit 1a, the first opening portion 12a and the second opening portion
12b are arranged, for example, at opposite end portions in a specific direction. The
first opening portion 12a and the second opening portion 12b, in the respective portions
of the outer surface of the body wall 12, are arranged at a pair of corners in a diagonal
relationship. With this configuration, the air flow sent to the inside of the body
housing 10 of the lamp unit 1a through the pump 15 is likely to reach a large area
inside the body housing 10. Consequently, in the lamp unit 1a, fogging is less likely
to occur on the inner surface of the light-transmitting member 11. Even if fogging
occurs, the fogging is likely to be more effectively removed. At least one of the
first opening portion 12a and the second opening portion 12b may be positioned in
the side portion of the body wall 12.
[0023] The body wall 12 may have a plurality of the first opening portions 12a. In the case
where the body wall 12 has the plurality of first opening portions 12a, the lamp unit
1a may include a plurality of the pumps 15, with the gas discharge ports 15a of the
plurality of pumps 15 connected to separate first opening portions 12a. The gas discharge
port 15a of a single pump 15 may be connected to the plurality of first opening portions
12a.
[0024] The body wall 12 may have a plurality of the second opening portions 12b. As shown
in FIG. 2B, the body wall 12 may have two second opening portions 12b, for example.
In plan view of the portion of the outer surface of the body wall 12 that forms the
rear of the lamp unit 1a, the first opening portion 12a and each of the plurality
of second opening portions 12b are arranged, for example, at opposite end portions
in different specific directions. The two second opening portions 12b, in the respective
portions of the outer surface of the body wall 12, are arranged, for example, at a
pair of corners adjacent to each other. For example, as shown in FIG. 2B, in plan
view of the portion of the outer surface of the body wall 12 that forms the rear of
the lamp unit 1a, one of the plurality of second opening portions 12b is arranged
away from a straight line L that intersects both the first opening portion 12a and
another second opening portion 12b. At least one of the first opening portion 12a
and the plurality of second opening portions 12b may be positioned in the side portion
of the body wall 12.
[0025] The body wall 12 may have an opening portion communicating with the external space
of the body housing 10, in addition to the first opening portion 12a and the second
opening portion 12b. For example, the body wall 12 has three opening portions or less.
[0026] In the body wall 12, the shape of the first opening portion 12a and the second opening
portion 12b are not limited to particular shapes. In each of the first opening portion
12a and the second opening portion 12b, the end portion of the opening portion that
abuts the external space of the body housing 10 may be positioned flush with the periphery
of the opening portion, or may be positioned at the tip of a portion protruding from
the periphery of the opening portion.
[0027] The ventilation member 20 may be a patch-type ventilation member, a snap-fit type
ventilation member, a cap-type ventilation member, or any other type of ventilation
member.
[0028] In the case where the ventilation member 20 is a patch-type ventilation member, the
ventilation member 20 is attached to a portion of the body wall 12 that abuts the
second opening portion 12b, in a state where an adhesive tape overlapping the gas-permeable
membrane along the periphery of the gas-permeable membrane is in contact with the
outer surface of the body wall 12 around the second opening portion 12b.
[0029] FIG. 3 shows an example of the ventilation member 20, where the ventilation member
20 is a snap-fit type ventilation member. As shown in FIG. 3, the ventilation member
20 includes a gas-permeable membrane 21, a supporting portion 22, and a protruding
portion 23. The supporting portion 22 is an annular and plate-shaped portion in which
a through hole forming a portion of a ventilation path 25a is formed at the center,
and the gas-permeable membrane 21 is fixed to the supporting portion 22 to cover the
through hole. The protruding portion 23 is a tubular portion protruding from the supporting
portion 22 at the center of the supporting portion 22. The protruding portion 23 includes
a plurality of leg portions 23g arranged away from each other around the axis of the
protruding portion 23. The tip portion of each of the plurality of leg portions 23g
has a protrusion 23a protruding outward in a direction perpendicular to the axis of
the supporting portion 22. The protrusion 23a faces an inner surface 12m of the body
wall 12. The ventilation member 20 is configured such that the protrusion 23a allows
the ventilation member 20 to snap-fit onto the body wall 12. The ventilation member
20 further includes a sealing member 24, for example. The sealing member 24 is disposed
around the protruding portion 23 at a corner formed by the outer surface of the protruding
portion 23 and the supporting portion 22. The sealing member 24 is an annular member
and is disposed in contact with the supporting portion 22 and the outer surface of
the body wall 12. This seals the ventilation path 25a against the space outside the
body wall 12 between the supporting portion 22 and the outer surface of the body wall
12.
[0030] As shown in FIG. 3, the ventilation member 20 further includes a cover 26, for example.
The cover 26 covers the gas-permeable membrane 21, forming a ventilation path 25b
between the gas-permeable membrane 21 and the cover 26. An opening is formed on the
lateral side of the cover 26, allowing ventilation between the space inside the body
wall 12 and the space outside the body wall 12 through the ventilation path 25a and
the ventilation path 25b.
[0031] FIG. 4 shows an example of the ventilation member 20, where the ventilation member
20 is a cap-type ventilation member. As shown in FIG. 4, the cap-type ventilation
member 20 includes, for example, the gas-permeable membrane 21, a cap 27, and an inner
member 28. The ventilation member 20 is attached to the body wall 12 with the inner
surface of the inner member 28 in contact with the outer surface of a protruding portion
12p. Consequently, an airtight state is maintained between the inner surface of the
inner member 28 and the outer surface of the protruding portion 12p. The protruding
portion 12p is a tubular portion protruding outward in the body wall 12, inside which
the second opening portion 12b is formed. The inner member 28 is a tubular member.
To one end of the inner member 28, the gas-permeable membrane 21 is fixed to cover
the inner space of the inner member 28. The cap 27 is attached to the inner member
28 to cover the gas-permeable membrane 21. There exists, between a portion of the
side wall of the cap 27 and the inner member 28, a gap included in a portion of the
ventilation path.
[0032] In the lamp unit 1a, the combination of the body housing 10, the pump 15, and the
ventilation member 20 is not limited to a particular combination. For example, the
body housing 10, the pump 15, and the ventilation member 20 form a combination satisfying
the requirements represented by the following expressions (Ia) and (Ib). In this case,
in the lamp unit 1a, fogging is less likely to occur on the inner surface of the light-transmitting
member 11. Even if fogging occurs, the fogging is likely to be more effectively removed.
In these requirements, p is the pressure [kPa] inside the body housing 10 during operation
of the pump 15, t is the discharge time [s] of the pump 15, P is the air permeability
coefficient [cm
3/(Pa•s•cm
2)] of the ventilation member 20, A is the permeable area [cm
2] of the ventilation member 20, and V is the spatial volume [cm
3] inside the lamp unit 1a. The pressure p is a gauge pressure.

[0033] The combination of the body housing 10, the pump 15, and the ventilation member 20
may satisfy the requirement 1000p•t•P•A/V ≥ 4, 1000p•t•P•A/V ≥ 5, or 1000p•t•P•A/V
≥ 10. The combination of the body housing 10, the pump 15, and the ventilation member
20 satisfies the requirement 1000p•t•P•A/V ≤ 20, for example.
[0034] The pressure p inside the body housing 10 can be regulated, for example, by a valve
disposed between the gas discharge port 15a and the first opening portion 12a. In
the case where the pump 15 has the function of adjusting its output in multiple stages,
the function may be used to regulate the pressure p.
[0035] The time t is desirably 240 seconds or less, and more desirably 180 seconds. Owing
to the satisfaction of the requirement (Ia), fogging is less likely to occur on the
inner surface of the light-transmitting member 11, even with a discharge time t of
the pump 15 being as short as described above. Even if fogging occurs, the fogging
is likely to be effectively removed. The time t may be 10 seconds or more.
[0036] The permeability coefficient P of the ventilation member 20 can be determined, for
example, by dividing the air volume [cm
3/(cm
2•s)] obtained according to Frajour type method (Method A) specified in Japanese Industrial
Standards (JIS) L 1096:2010 by the pressure of 125 Pa indicated by the inclined barometer
of a Frajour type testing machine. The permeability coefficient P may also be determined
by converting the measured value indicating air permeability, as measured using an
air permeability testing machine other than a Frajour type testing machine, such as
a Gurley densometer, into dimensions of [cm
3/(Pa•s•cm
2)].
[0037] The permeability coefficient P is not limited to a particular value. The permeability
coefficient P is, for example, adjusted such that the requirement in (Ia) is satisfied.
The permeability coefficient P is, for example, 0.00008 to 0.80293 [cm
3/(Pa•s•cm
2)]. In this case, the requirement (Ia) is likely to be satisfied and fogging is less
likely to occur on the inner surface of the light-transmitting member 11. Even if
fogging occurs, the fogging is likely to be more effectively removed. The permeability
coefficient P is desirably 0.00008 to 0.8 [cm
3/(Pa•s•cm
2)], more desirably 0.0008 to 0.16 [cm
3/(Pa•s•cm
2)], and even more desirably 0.004 to 0.03 [cm
3/(Pa•s•cm
2)].
[0038] The permeable area A of the ventilation member 20 is the area of the air-permeable
portion of the ventilation member 20. For example, in the case where the ventilation
member 20 includes a gas-permeable membrane, the effective area of the air-permeable
portion of the gas-permeable membrane corresponds to the permeable area A. In the
ventilation member 20, for example, in the case where the periphery of the gas-permeable
membrane is fixed to a given supporting member and the inner side of the periphery
of the gas-permeable membrane abuts the ventilation path, the area of the portion
of the gas-permeable membrane that abuts the ventilation path on the inner side of
the periphery of the gas-permeable membrane can correspond to the permeable area A.
For example, in the case where the gas-permeable membrane is fixed to the supporting
member with an annular adhesive tape, the area of the inner portion of the annular
adhesive tape can correspond to the permeable area A. In addition, in the case where
the gas-permeable membrane is fixed to the supporting member by welding, the area
of the inner portion of the welded portion can correspond to the permeable area A.
In the case where the lamp unit 1a includes a plurality of the ventilation members
20, the sum total of the permeable areas of the ventilation members 20 can correspond
to the permeable area A.
[0039] The permeable area A of the ventilation member 20 is not limited to a particular
value. The permeable area A is, for example, adjusted such that the requirement in
(Ia) is satisfied. The permeable area A is, for example, 0.03142 to 50.26548 cm
2. In this case, the requirement in (Ia) is likely to be satisfied. Even if fogging
occurs on the inner surface of the light-transmitting member 11, the fogging is likely
to be more effectively removed. The permeable area A may be 0.785 to 38.48 cm
2 or 1.767 to 28.27 cm
2.
[0040] The maximum diameter of the portion of the ventilation member 20 having the permeable
area A is, for example, 2 to 80 mm, and may be 10 to 70 mm or 15 to 60 mm.
[0041] The spatial volume V inside the lamp unit 1a can be determined, for example, by injecting
water into the lamp unit 1a until the entire space inside the lamp unit 1a is filled
and applying the relationship V = (W2 - W1)/ρ
w. In this relationship, W2 is the weight [kg] of the lamp unit 1a after water injection,
W1 is the weight [kg] of the lamp unit 1a before water injection, and ρ
w is the density of water, 1.0 × 10
-3 kg/cm
3.
[0042] The spatial volume V is not limited to a particular value. The spatial volume V is,
for example, adjusted such that the requirement in (Ia) is satisfied. The spatial
volume V is, for example, 1000 to 20000 cm
3. Owing to the spatial volume V being 1000 cm
3 or more, light generated from the light source 13 is likely to be emitted in a desired
state. Owing to the spatial volume V being 20000 cm
3 or less, fogging is less likely to occur on the inner surface of the light-transmitting
member 11. Even if fogging occurs, the fogging is likely to be effectively removed.
[0043] The spatial volume V is desirably 2000 to 18000 cm
3, and more desirably 3000 to 15000 cm
3.
[0044] In the lamp unit 1a, ventilation of the body housing 10 is performed by operation
of the pump 15. In this case, the pump 15, for example, discharges a gas toward the
body housing 10 such that the requirements represented by the above expressions (Ia)
and (Ib) are satisfied.
[0045] The application of the lamp unit 1a is not limited to a particular application. For
example, the lamp unit 1a is for a vehicle. In a vehicle, events such as vehicle washing
and rainfall rapidly cool the inside of the lamp and fogging is likely to occur on
the inner surface of the light-transmitting member. According to the lamp unit 1a,
fogging is less likely to occur on the inner surface of the light-transmitting member,
and even if fogging occurs, the fogging is likely to be effectively removed. Therefore,
the lamp unit 1a can enhance the value of a vehicle including the lamp unit 1a.
[0046] The lamp unit 1a may be a lamp unit for a headlight, a lamp unit for a small light,
a lamp unit for a fog light, or a lamp unit for a brake light.
Examples
[0047] The present invention will be described in more detail below with reference to examples.
The present invention is not limited to the following examples.
<Example 1A>
[0048] Water was injected into the inside of the headlamp of Chery Tiggo 8 (headlamp C)
until the entire space inside the headlamp C was filled, and the above relationship
V = (W2 - W1)/ρ
w was applied to determine the spatial volume V inside the headlamp C. The result indicated
that the spatial volume V inside the headlamp C was 9400 cm
2. All the valves attached to the housing of the headlamp C were detached and the headlamp
was dried in an 80°C environment for 24 hours. Other conditions may be employed for
drying the headlamp as long as the inside of the headlamp can be sufficiently dried.
For example, the headlamp can also be dried in a 50°C environment over 1 week.
[0049] The dried headlamp C was transferred into a thermo-hygrostat maintained in an environment
with a temperature of 40°C and a relative humidity of 90% and allowed to stand for
24 hours. Thus, the humidity control process for the headlamp C was performed. The
headlamp C was taken out of the thermo-hygrostat and left in an environment with a
temperature of 20°C and a relative humidity of 65% for 1 hour. Thus, the air inside
the headlamp C was displaced. The suction port of FLEXTAILGEAR portable compact pump
TINY PUMP X was covered with a gas-permeable membrane to obtain a pump according to
the example. This pump had a maximum discharge pressure of 3.5 kPa. The gas-permeable
membrane was fixed to the pump with a double-sided adhesive tape. The air permeability
coefficient of this gas-permeable membrane was 0.01204 cm
3/(Pa•s•cm
2). This permeability coefficient was determined by dividing the air volume [cm
3/(cm
2•s)] obtained according to Frajour type method (Method A) specified in JIS L 1096:2010
by the pressure of 125 Pa indicated by the inclined barometer of a Frajour type testing
machine. An opening portion formed at the upper left of the rear of the headlamp C
and the discharge port of the pump according to the example were connected to each
other via a flow path member that includes a polyvinyl chloride tube. A pressure gauge
and a valve were attached to the flow path member at points along the flow path. An
opening portion formed in the side portion of the housing of the headlamp C, positioned
at the lower right in plan view of the rear of the headlamp C, was covered with a
gas-permeable membrane a. The air permeability coefficient P of the gas-permeable
membrane a was 0.01204 cm
3/(Pa•s•cm
2). The permeability coefficient P of the gas-permeable membrane was determined by
dividing the air volume [cm
3/(cm
2•s)] obtained according to Frajour type method (Method A) specified in JIS L 1096:2010
by the pressure of 125 Pa indicated by the inclined barometer of a Frajour type testing
machine. The permeable area A of the gas-permeable membrane a was 20.43 cm
2. In this manner, a lamp unit according to Example 1A was produced. FIG. 5A is a photograph
of the front of the headlamp of Chery Tiggo 8, and FIG. 5B is a photograph of the
bottom of this headlamp. FIG. 5C is a photograph of the rear of the lamp unit according
to Example 1A. In these photographs, the region enclosed by the dashed line near the
sign "p" indicates the position of the opening portion connected to the discharge
port of the pump, and the region enclosed by the dashed line near the sign "m" indicates
the position of the opening portion covered with the gas-permeable membrane.
<Example 1B>
[0050] A gas-permeable membrane b was used in place of the gas-permeable membrane a. Except
for this, the same procedure as in Example 1A was performed to produce a lamp unit
according to Example 1B. The permeability coefficient P of the gas-permeable membrane
b was 0.00127 cm
3/(Pa•s•cm
2).
<Comparative Example 1>
[0051] The headlamp was not connected to the pump according to the example, did not use
the gas-permeable membrane a, and was hermetically sealed. Except for this, the same
procedure as in Example 1A was performed to produce a lamp unit according to Comparative
Example 1.
<Example 2A>
[0052] Water was injected into the inside of the headlamp of GEELY Emgrand X7 (headlamp
G) until the entire space inside the headlamp G was filled, and the above relationship
V = (W2 - W1)/ρ
w was applied to determine the spatial volume V inside the headlamp G. The result indicated
that the spatial volume V inside the headlamp G was 8000 cm
2. All the valves attached to the housing of the headlamp G were detached and the headlamp
was dried in an 80°C environment for 24 hours.
[0053] The dried headlamp G was transferred into a thermo-hygrostat maintained in an environment
with a temperature of 40°C and a relative humidity of 90% and allowed to stand for
24 hours. Thus, the humidity control process for the headlamp G was performed. The
headlamp G was taken out of the thermo-hygrostat and left in an environment with a
temperature of 20°C and a relative humidity of 65% for 1 hour. Thus, the air inside
the headlamp G was displaced. An opening portion formed at the left end portion of
the rear of the headlamp G and the discharge port of the pump according to the example
were connected to each other via a flow path member that includes a polyvinyl chloride
tube. A pressure gauge and a valve were attached to the flow path member at points
along the flow path. An opening portion formed in the housing of the headlamp G, positioned
at the right end portion in plan view of the rear of the headlamp G, was covered with
the gas-permeable membrane a. The permeable area A of the gas-permeable membrane a
was 33.18 cm
2. In this manner, a lamp unit according to Example 2A was produced. FIG. 6A is a photograph
of the front of the headlamp of GEELY Emgrand X7, and FIG. 6B is a photograph of the
rear of this headlamp. FIG. 6C is a photograph of the rear of the lamp unit according
to Example 2A. In these photographs, the region enclosed by the dashed line near the
sign "p" indicates the position of the opening portion connected to the discharge
port of the pump, and the region enclosed by the dashed line near the sign "m" indicates
the position of the opening portion covered with the gas-permeable membrane.
<Example 2B>
[0054] The permeable area A of the gas-permeable membrane a was changed to 2.85 cm
2. Except for this, the same procedure as in Example 2A was performed to produce a
lamp unit according to Example 2B.
<Comparative Example 2>
[0055] The headlamp was not connected to the pump according to the example, did not use
the gas-permeable membrane a, and was hermetically sealed. Except for this, the same
procedure as in Example 2A was performed to produce a lamp unit according to Comparative
Example 2.
<Example 3A>
[0056] Water was injected into the inside of the headlamp of Ford Escape (headlamp F) until
the entire space inside the headlamp F was filled, and the above relationship V =
(W2 - W1)/ρ
w was applied to determine the spatial volume V inside the headlamp F. The result indicated
that the spatial volume V inside the headlamp F of Ford Escape was 13400 cm
2. All the valves attached to the housing of the headlamp F were detached and the headlamp
was dried in an 80°C environment for 24 hours.
[0057] The dried headlamp F was transferred into a thermo-hygrostat maintained in an environment
with a temperature of 40°C and a relative humidity of 90% and allowed to stand for
24 hours. Thus, the humidity control process for the headlamp F was performed. The
headlamp F was taken out of the thermo-hygrostat and left in an environment with a
temperature of 20°C and a relative humidity of 65% for 1 hour. Thus, the air inside
the headlamp F was displaced. An opening portion formed at the lower right end portion
of the rear of the headlamp F and the discharge port of the pump according to the
example were connected to each other via a flow path member that includes a polyvinyl
chloride tube. A pressure gauge was attached to the flow path member at a point along
the flow path. An opening portion formed in the housing of the headlamp F, positioned
at the upper left end portion in plan view of the rear of the headlamp F, was covered
with the gas-permeable membrane a. The permeable area A of the gas-permeable membrane
a was 20.43 cm
2. In this manner, a lamp unit according to Example 3A was produced. FIG. 7A is a photograph
of the front of the headlamp of Ford Escape, and FIG. 7B is a photograph of the rear
of this headlamp. FIG. 7C is a photograph of the rear of the lamp unit according to
Example 3A. In these photographs, the region enclosed by the dashed line near the
sign "p" indicates the position of the opening portion connected to the discharge
port of the pump, and the region enclosed by the dashed line near the sign "m" indicates
the position of the opening portion covered with the gas-permeable membrane.
<Example 3B>
[0058] The permeable area A of the gas-permeable membrane a was changed to 10.21 cm
2. Except for this, the same procedure as in Example 3A was performed to produce a
lamp unit according to Example 3B.
<Example 3C>
[0059] The gas-permeable membrane b was used in place of the gas-permeable membrane a, and
the permeable area A of the gas-permeable membrane b was adjusted to 38.48 cm
2. Except for this, the same procedure as in Example 3A was performed to produce a
lamp unit according to Example 3C. The permeability coefficient P of the gas-permeable
membrane b was 0.00127 cm
3/(Pa•s•cm
2).
<Example 3D>
[0060] The permeable area A of the gas-permeable membrane a was changed to 2.10 cm
2. Except for this, the same procedure as in Example 3A was performed to produce a
lamp unit according to Example 3D.
<Comparative Example 3>
[0061] The headlamp was not connected to the pump according to the example, did not use
the gas-permeable membrane a, and was hermetically sealed. Except for this, the same
procedure as in Example 3A was performed to produce a lamp unit according to Comparative
Example 3.
[Evaluation of ventilation performance]
[0062] Ventilation performance was evaluated for the lamp units according to the examples
and comparative examples. The lamp units produced were each placed in an environment
with a temperature of 20°C and a relative humidity of 65%, and eight beam lamps were
arranged in front of the lens of each lamp unit. The beam lamps used were the diffusing
beam lamp BRF 110V 120W Type 150 manufactured by Kyokko Electric Industrial Co., Ltd.
The distance between each lamp unit and the eight beam lamps was adjusted to approximately
700 mm. The eight beam lamps were lighted, and each lamp unit was illuminated with
light emitted from the eight beam lamps for 2 hours. The temperature of the lens surface
of each lamp unit increased from the start of lighting of the eight beam lamps. Approximately
60 minutes after the start of lighting of the eight beam lamps, the temperature of
the lens surface of each lamp unit was maintained at approximately 40 to approximately
60°C. Additionally, provided that each lamp unit is warmed as described above, the
evaluation of ventilation performance may employ a method for warming each lamp unit
other than the method using beam lamps.
[0063] In the evaluation of ventilation performance for each of the lamp units according
to the examples, at the point in time when the power to the beam lamps was switched
off to extinguish the beam lamps, the pump in the lamp unit was activated. At a given
point in time after the power to the beam lamps was switched off, a 90-second water
pouring was performed on the lens surface of each lamp unit. The temperature of the
water used for the water pouring was approximately 11°C. After the water pouring was
completed, the lens surface was checked for the presence or absence of fogging. In
the case where fogging was observed, the time T required for the fogging to be removed
was measured. Additionally, in the case where no fogging was observed, the time was
determined to be 0 minutes. In the pump units according to the examples, at the point
in time when the power to the beam lamps was switched off, the pump was activated
and operated according to the following Pattern I or Pattern II. The pressure p inside
the housing of the lamp unit during operation of the pump was read from the pressure
gauge. The pressure p is a gauge pressure. Table 1 shows the pump unit used for each
evaluation, the operation pattern of the pump, the pressure p [kPa] inside the housing
of the lamp unit during operation of the pump, the discharge time t [s] of the pump,
and the time T [min] required for fogging to be removed. FIG. 8 shows the relationship
between the time T required for fogging to be removed and the value of 1000•p•t•P•A/V
in each evaluation.
[0064] Pattern I: Operate the pump for a given discharge time t before water pouring, and
stop the pump immediately before the start of water pouring.
[0065] Pattern II: Operate the pump during water pouring as well, and stop the pump 1 minute
after the start of water pouring.
[0066] As shown in Table 1, the times T in the evaluation of ventilation performance using
the pump units according to the examples (Evaluation Nos. 1 to 14) were shorter than
the times T in the evaluation of ventilation performance using the pump units according
to Comparative Examples 1 to 3 (Evaluation Nos. 15 to 17). Therefore, it is understood
that the pump units according to the examples can exhibit better ventilation performance
than the pump units according to Comparative Examples 1 to 3.
[0067] According to FIG. 8, it is understood that satisfying the requirement 1000•p•t•P•A/V
≥ 3.0 causes no occurrence of fogging or removes fogging on the lens surface with
a shorter time.
[0068] A first aspect of the present invention provides a lamp unit including:
a body housing including: a light-transmitting member; a body wall joined to the light-transmitting
member to form a housing; and a first opening portion and a second opening portion
positioned in the body wall and each forming an opening communicating with an external
space of the housing;
a light source disposed inside the body housing; and
a pump having a gas discharge port connected to the first opening portion.
[0069] A second aspect of the present invention provides the lamp unit according to the
first aspect, further including a ventilation member for ventilation between the body
housing and the external space, wherein
the ventilation member is provided at the second opening portion.
[0070] A third aspect of the present invention provides the lamp unit according to the first
or second aspect, wherein
the pump has a maximum discharge pressure of 0.5 to 20.0 kPa.
[0071] A fourth aspect of the present invention provides the lamp unit according to the
second aspect, wherein
the body housing, the pump, and the ventilation member form a combination satisfying
requirements represented by the following expressions (Ia) and (Ib)


where p is a pressure [kPa] inside the body housing during operation of the pump,
t is a discharge time [s] of the pump, P is an air permeability coefficient [cm3/(Pa•s•cm2)] of the ventilation member, A is a permeable area [cm2] of the ventilation member, and V is a spatial volume [cm3] inside the lamp unit.
[0072] A fifth aspect of the present invention provides the lamp unit according to the second
aspect, wherein
the air permeability coefficient of the ventilation member is 0.00008 to 0.80293 cm
3/(Pa•s•cm
2).
[0073] A sixth aspect of the present invention provides the lamp unit according to the second
aspect, wherein
the permeable area of the ventilation member is 0.03142 to 50.26548 cm
2.
[0074] A seventh aspect of the present invention provides the lamp unit according to any
one of the first to sixth aspects, wherein
the spatial volume inside the lamp unit is 1000 to 20000 cm
3.
[0075] An eighth aspect of the present invention provides the lamp unit according to any
one of the first to seventh aspects, being for a vehicle.
[0076] A ninth aspect of the present invention provides a ventilation method for a body
housing of a lamp,
the lamp including a lamp unit,
the lamp unit including:
the body housing including: a light-transmitting member; a body wall joined to the
light-transmitting member to form a housing; and a first opening portion and a second
opening portion positioned in the body wall and each forming an opening communicating
with an external space of the housing;
a light source disposed inside the body housing;
a pump having a gas discharge port connected to the first opening portion; and
a ventilation member for ventilation between the body housing and the external space,
and
the ventilation method including:
allowing the pump to discharge a gas toward the body housing such that requirements
represented by the following expressions (IIa) and (IIb) are satisfied,


where p is a pressure [kPa] inside the body housing during operation of the pump,
t is a discharge time [s] of the pump, P is an air permeability coefficient [cm3/(Pa•s•cm2)] of the ventilation member, A is a permeable area [cm2] of the ventilation member, and V is a spatial volume [cm3] inside the lamp unit.
[Table 1]
Eval. No. |
Pump unit |
Pressure p [kPa] |
Pump discharge time t [s] |
Pump operation pattern |
Gas-permeable membrane permeability coefficient P [cm3/(Pa•s•cm2)] |
Gas-permeable membrane permeable area A [cm2] |
Ventilation volume 1000p•t•P•A [cm3] |
Lamp type |
Spatial volume V inside lamp [cm3] |
1000p•t•P•A/V |
Eval. result [min] |
1 |
Ex. 1A |
2.0 |
90 |
I |
0.01204 |
20.43 |
44272.01 |
C |
9400 |
4.7 |
0 |
2 |
Ex. 1B |
3.0 |
90 |
I |
0.00127 |
20.43 |
7004.83 |
0.7 |
24 |
3 |
Ex. 2A |
0.8 |
150 |
I |
0.01204 |
33.18 |
47942.90 |
G |
8000 |
6.0 |
0 |
4 |
1.8 |
150 |
I |
107871.53 |
13.5 |
0 |
5 |
Ex. 2B |
4.0 |
150 |
I |
0.01204 |
2.85 |
20588.40 |
2.6 |
10 |
6 |
Ex. 3A |
2.0 |
90 |
I |
0.01204 |
20.43 |
44272.01 |
|
|
3.3 |
15 |
7 - |
2.0 |
150 |
I |
73786.68 |
|
|
5.5 |
0 |
8 |
2.0 |
150 |
II |
73786.68 |
|
|
5.5 |
0 |
9 |
1 |
150 |
II |
36893.34 |
F |
13400 |
2.8 |
3.5 |
10 |
Ex. 3B |
2.5 |
150 |
I |
0.01204 |
10.21 |
46116.68 |
|
|
3.4 |
0.75 |
11 |
Ex. 3C |
3.5 |
300 |
I |
0.00127 |
38.48 |
51319.09 |
|
|
3.8 |
0 |
12 |
Ex. 3D |
3.5 |
120 |
I |
0.01204 |
2.10 |
10619.28 |
|
|
0.8 |
22 |
13 |
1 |
120 |
II |
3034.08 |
|
|
0.2 |
12 |
14 |
4 |
120 |
II |
12136.32 |
|
|
0.9 |
6 |
15 |
Comp. Ex. 1 |
0.0 |
0 |
I |
Hermetically sealed |
0.00 |
0 |
C |
9400 |
0.0 |
40 |
16 |
Comp. Ex. 2 |
0.0 |
0 |
I |
Hermetically sealed |
0.00 |
0 |
G |
8000 |
0.0 |
55 |
17 |
Comp. Ex. 3 |
0.0 |
0 |
I |
Hermetically sealed |
0.00 |
0 |
F |
13400 |
0.0 |
45 |
I: Operate pump for given discharge time t before water pouring, and stop pump immediately
before start of water pouring. II: Operate pump during water pouring as well, and
stop pump 1 minute after start of water pouring. |