GB2516551A - Condensation reduction in vehicle light assembly - Google Patents

Abstract

A vehicle light assembly 1 comprises a housing 2 which an interior chamber with a light outlet 4 formed therein. An illumination means 3 is mounted in the interior chamber of the housing for projecting light through the light outlet 4. An ionic membrane 6 is associated with the housing, the ionic membrane having a first, de-humidifying side 6a and a second, discharge side 6b. The de-humidifying side 6a is in fluid communication with the chamber of the housing 2 such that moisture in the atmosphere in the chamber is extracted by the ionic membrane 6.

Description

Condensation Reduction in Vehicle Light Assembly The present invention relates to improvements in relation to vehicle light assemblies and more particularly to systems for reducing the occurrence of condensation in vehicle light assemblies.

A vehicle light assembly is an enclosed, though not normally sealed, module which typically includes a light source such as a bulb, a lens or glass for creating a required light pattern, in one direction from the assembly, and reflectors for ensuring the maximum amount of light from the light source is directed out of the lens and not wasted out the back of the assembly.

The lens or glass is usually carefully designed to produce a particular light pattern from the, assembly which gives maximum illumination to the area in front of the assembly whilst avoiding issues such as dazzling other drivers on the road. With the move towards lower energy light sources such as LED baáed bulbs, the critical importance of the design of the lens and the light pattern produced thereby has become even more important in ensuring adequate light is produced by the assembly.

However, due to the very nature of the application of vehicle light assemblies in vehicles which are exposed to many different environment conditions and changes in temperature, as well as the fact that the assemblies are typically not sealed, there has been a long standing problem of condensation forming on the inside surface the lens or glass of the assembly.

The formation of condensation is particularly prevalent in vehicle light assemblies because of the variation in temperatures to which such an assembly is typically exposed during use -heat from the engine and light source itself contrasting with cold air which is usually incident on the front of the glass as the vehicle is moving.

When condensation does form, the droplets of water will reflect, refract, and diffract the light which passes through the lens, disrupting the carefully designed light pattern which is projected from the lens: Ionic membranes are known in the art particularly, in dehumidifiers. An ionic membrane attracts moisture to its de-humidifying side and then splits the water vapour into hydrogen and oxygen before allowing these gases to pass through it where they are discharged on the discharge side of the membrane. As a result, the moisture content of the atmosphere on the de-humidifying side of the membrane is reduced, and hence, so too is the humidity.

According to the present invention, there is provided a vehicle light assembly comprising a housing defining an interior chamber and having a light outlet formed therein, an illumination means mounted in the interior chamber of the housing for projecting light through the light outlet, and at least one ionic membrane associated with the housing, the ionic membrane having a first, de-humidifying side and a second, discharge side, the de-humidifying side being in fluid communication with the chamber of the housing such that moisture in the atmosphere in the chamber is extracted by the ionic membrane.

A vehicle light assembly in accordance with the invention has the advantage that it provides a particularly effective way of controlling the occurrence of condensation in vehicle lights.

Preferably, the discharge side of the ionic membrane is located to expel gas and/or water vapour from the ionic membrane outside of the housing. The housing preferably includes a discharge aperture in which the ionic membrane is mounted with its de-humidifying side facing into the chamber and its discharge side facing away from the chamber In one embodiment, the assembly includes a membrane chamber which is separate to the interior chamber of the housing and fluidly connected thereto by means of a duct, the ionic membrane being mounted in the membrane chamber with its de-humidifying side fluidly connected to the interior chamber by the duct. The membrane chamber may be remote from the housing and is connectable to multiple housing to enable the ionic membrane to de-humidify the atmosphere in multiple light assemblies: The ionic membrane may advantageously be mounted in the interior chamber on a hollow stem so as to be located away from the wails of the housing, the hollow stem acting as a vent port for the discharge side of the ionic membrane to the outside of the housing.

Advantageously, the ionic membrane has a hydrophobic membrane or protector associated with its discharge side to prevent the ingress of moisture. The ionic membrane is preferably enclosed within a case, which may be formed as two halves fixed together.

Reference herein to vehicle light assembly will be understood to mean a light assembly suitable for use in any vehicle including, but not restricted to land, sea, air and space vehicles.

In order that the invention may be well understood, there will now be described some embodiments thereof, given by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of.a vehicle light assembly according to a first embodiment of the invention; Figure 2 is a diagrammatic representation of a vehicle light assembly according to a second embodiment of the invention; Figure 3 is a diagrammatic representation of a vehicle light assembly according to a third embodiment of the invention; Figure 4 is a diagrammatic representation of a vehicle light assemblyaccording to a fourth embodiment of the invention; and Figure 5 is an enlarged view of Figure 3 showing an example of a practical configuration of the ionic membrane.

Referring first to Figure 1, there is shown a first embodiment of a vehicle light assembly 1 according to the invention. The light assembly I has a housing 2 in which is mounted a lamp 3. At one end of the housing is mounted a lens 4 through which light from the lamp 3 is projected. The exact form of the lens is not critical to the invention and will instead be dictated by the light pattern requirements for the particular application of the assembly 1.

An aperture 5 is formed in the housing 2 in which is mounted an ionic membrane S with its cle-humidifying side 6a directed towards the interior of the housing and discharge side 6b directed to the exterior of the housing 2. In the illustrated embodiment the aperture is formed in the end of the housing opposite to the housing so as to minimise impact on the light from the lamp, but other locations are also possible. The ionic membrane thereby attracts moisture which is present in the atmosphere within the housing, breaks the water molecules down into hydrogen and oxygen and expels those gases from the discharge side Sb exteriorly of the assembly, thereby reducing the humidity in the assembly and the occurrence of condensation.

Figure 2 shàws a second embodiment of the invention in which like features are identified using the same reference numerals. In this embodiment, the ionic membrane is mounted in a separate chamber of the housing 2 with a duct 7 connecting the membrane chamber to the main housing. In all other respects the configuration and operation of the second embodiment is the same as the first. This arrangement has the advantage that the smaller foot print of the duct 7 in the main chamber enables reflectors to be included on the back surface, decreasing the light loss in the unit. Also, the configuration allows gas produced by 4.

the membrane to be vented away from the housing 2 whilst still allowing the vapour inside the enclosure to touch the de-humidifying side 6a of the membrane 6.

Figure 3 shows a third embodiment of the invention which differs from the second in that the duct 7 acts to extend the membrane towards the centre of the housing 2, thereby increasing the exposure of the membrane 6 to moisture in the assembly I and hence the effectiveness of the membrane 6 in reducing I eliminating condensation.

Figure 4 shows an example of how a single ionic membrane 6 may be used to de-humidify multiple light assemblies 1. In the illustrated embodiment, two light assemblies are shown for illustration purposes but it will be understood that the principle can be expanded to allow the membrane 6 to support multiple assemblies, the practical limit being the de-humidifying power of the membrane 6.

This is achieved by providing each housing 2 with a duct 7 which leads to a separate, common chamber 9 in.which the ionic membrane 6 is housed. In this way the ai within each housing 2 can circulate to the ionic membrane 6 and be de-humidified.

It will also be understood that multiple ionic membranes may be provided within the same housing in order to increase the effectiveness.

Figure 5 illustrates an example of how the ionic membrane 6 may be configured and mounted in practice, illustrated in accordance with the embodiment of Figure 3. The membrane 6 is mounted in a case 11, which in the illustrated embodiment if formed in two halves 11 a, 11 b which are fixed together, such as by gluing, welding or the like. The fixing of the two halves should form a seal 8 around the edge of the membrane 6 so as to prevent ingress of moisture through the casing to the membrane 6 which would increase the load thereon. The casing itself may be made of any suitable material. although non-thermal conducting material such as plastic, fibreglass or the like is preferred over metal as they have a lower tendency to promote the formation of condensation.

A hydrophobic membrane 10 may also be provided on the discharge side 6b of the ionic membrane 6, which allows the exchange of gas but prevents moisture ingress. The hydrophobic membrane 10 will also act to prevent foreign bodies from entering the ionic membrane 6 such as insects and debris. The hydrophobic membrane 10 should be positioned as close as possible to the ionic membrane 6 to prevent condensation from forming between them.

Power for the assembly typically requires a 12V-24V DC power supply which is converted to the required voltage using a regulator circuit. In one method this supply can be obtained from attaching to the daylight running lights of the vehicle as these are lights that are always on during the use of the vehicle and switch off when the vehicle is not in use, this method avoids problems associated with having a switched circuit inteôrated with the ignition to avoid battery drain whilst the vehicle is off. The power supply can be provided from any on board power supply including uninterruptable power supplies, voltage regulators and power suppliesthat remain energised until the voltage levels in the vehicle drop to an unacceptable level and cut the power to the dehumidifier to prevent unacceptable power drains from the vehicle.

The assembly may also be powered by means of a solar cell of sufficient capacity mounted on or in the vehicle where there is available tight.

This regulator circuit may be mounted inside the case 11, with 12V-24V DC supplied to it via cables from the vehicle. Alternatively the regulator circuit could be mounted external to the assembly as part of the cable or at the connection point to the 12V-24V supply.

Claims (10)

1. CLAIMS: 1. A vehicle light assembly comprising a housing defining an interior chamber and having a light outlet formed therein, an illumination means mounted in the interior chamber of the housing for projecting light through the light outlet, and at least one ionic membrane associated with the housing, the ionic membrane having a first, de-humidifying side and a second1 discharge side, the de-humidifying side being in fluid communication with the chamber of the housing such that moisture in the atmosphere in the chamber is extracted by the ionic membrane.
2. 2. A vehicle light assembly according to claim 1, wherein the discharge side of the ionic membrane is located to expel gas and/or watèr.vapour from the ionic membrane outside of the housing.
3. 3. A vehicle light assembly according to claim 1 or claim 2, wherein the housing includes a discharge aperture in which the ionic membrane is mounted with its de-humidifying side facing into the chamber and its discharge side facing away from the chamber.
4. 4. A vehicle light assembly according to claim 1 or claim 2, further including a membrane chamber which is separate to the interior chamber of the housing and fluidly connected thereto by means of a duct, the ionic membrane being mounted in the membrane chamber with its de-humidifying side fluidly connected to the interior chamber by the duct.
5. 5. A vehicle light assembly according to claim 4, wherein the membrane chamber is remote from the housing and is connectable to multiple housing to enable the ionic membrane to de-humidify the atmosphere in multiple light assemblies.
6. 6. A vehicle light assembly according to claim I or claim 2, wherein the ionic membrane is mounted in the interior chamber on a hollow stem so as to be located away from the walls of the housing, the hollow stem acting as a vent port for the discharge side of the ionic membrane to the outside of the housing.
7. 7. A vehicle light assembly according to any of the preceding claims, wherein the ionic membrane has a hydrophobic membrane or protectQr associated with its discharge side to prevent the ingress of moisture.
8. 8. A vehicle light assembly according to any of the preceding claims, wherein the ionic membrane is enclosed within a case.
9. 9. A vehicle light assembly according to any of the preceding claims, wherein multiple ionic membranes are associated with the housing.
10. 10. Any of the vehicle light assemblies substantially as herein described with reference to the accompanying drawings.