CARGO AREA LIGHTING SYSTEM FOR TRUCKS

Abstract: A lighting system using piped light is provided for the cargo space of a truck (10). A light source (32) mounted on the truck body (14) is energized by the truck electrical system through a switch (48) in the cab (12). Plural lithting fixtures are mounted to the roof (18) of the truck body for illuminating the cargo space. Each lighting fixture receives light which is piped through a separate light pipe (38) from the source to the fixture. There are two sets of lighting fixtures each of which is disposed in a linear array extending along a line from the front to the rear of the truck body. The light pipes (38A) for one set of lighting fixtures are all disposed in a first enclosure (96) and the light pipes (38B) for the other set of lighting fixtures are all disposed within a second enclosure (98). Certain sections (96A, 96B, 98A, 98B) of the enclosures are provided with a transparent lens and certain light pipes within the enclosures emit side light through the lens. A lighting fixture at the rear door (26) of the truck body is provided with an optical switch for turning the lighting fixture on or off.

Description: CARGO AREA LIGHTING SYSTEM FOR TRUCKS FIELD OF THE INVENTION This invention relates to truck lighting systems; more particularly, it relates to a lighting system for the cargo handling area of a truck using piped light. BACKGROUND OF THE INVENTION As is well-known, trucks having fully enclosed cargo space within the truck body are provided with a lighting system to facilitate loading and unloading of the cargo. Typically, the truck body, especially with long haul trucks, is long relative to its height and width to provide the desired cargo capacity. The longstanding practice in lighting the interior of the truck body has been to use a plurality of incandescent lamps mounted in the roof of the truck body and spaced from each other from front to rear. Typically, the lighting fixtures comprise a lamp housing recessed into the roof and enclosing an incandescent lamp and having a light distributing lens disposed on the housing between the housing and the cargo space so it is generally flush with the interior surface of the roof. This arrangement provides the required illumination without the light fixture intruding into the cargo space. The conventional incandescent lighting system described above has been found to be unsatisfactory because it is wasteful of energy, requires ongoing maintenance and is sometimes used in such a manner that it constitutes a fire hazard. In refrigerated trucks, i.e. those which have a refrigeration system for the cargo space, the heat that the incandescent lamps generate is largely dissipated into the refrigerated cargo space thus requiring more energy for refrigeration. Also, it is known that some truck drivers like to increase the illumination in the cargo space by replacing the standard low wattage incandescent lamps with higher wattage lamps resulting in increased heat generation and shortened bulb life. This practice adds to bulb replacement cost in maintaining the lighting system. Additionally, the conventional incandescent lighting system constitutes a fire hazard, especially when the truck body is loaded with cargo close to the incandescent lamp fixtures and the lights are inadvertently left on for a long time. Such conditions can cause truck fires which are not only dangerous to life and limb but also constitute increased costs to the trucking industry by reason of loss and increased insurance premiums. There has been a longstanding need in the trucking industry for a safe, effective and energy efficient lighting system for the cargo space in a container body of a truck. In the prior art, certain fiber optic or "light pipe" systems have been proposed for use on vehicles. The Johnson et al. patent 4,947,293 granted August 7, 1990 discloses a clearance lighting system for a semi trailer cargo container body. The lighting system includes a core light conducting material in the form of an elongated light conducting strip provided with a cladding material to provide a light guide. The core and cladding are constructed to provide lateral light emission as well as longitudinal propagation. A light source is adapted to end-illuminate the light guides for both sides of a container body from a single light source. A similar system which also provides a message panel is disclosed in Johnson patent 5,122,933 granted June 16, 1992. The Moore et al. patent 4,740,870 granted April 26, 1988 describes a fiber optic lighting system for boats. In this system, a plurality of fiber optic cables extend from a central light source to respective plurality of remote light fixtures to provide lighting at different locations on the boat. The Davenport et al. patent 4,811,172 granted March 7, 1989 describes an optical fiber lighting system particularly suited for automobiles and air craft. The lighting system comprises subsystems suitable for high and low beam illumination and rear illumination of an automobile. Each subsystem comprises a high intensity light source coupled to one end of each of a plurality of light pipes with each having their other end positioned relative to a reflective element and a lens. The reflective elements are arranged to provide a prescribed illumination pattern. The Finch et al. patent 5,184,883 granted February 9, 1993 discloses an automobile lighting system similar to that described in the above-referenced Davenport patent 4,811,172. The Finch et al. patent describes an indicating device that comprises a shutter having an opaque portion, a light blocking position in which the opaque portion blocks the passage of light from the output end of a light guide to a lens and a non-blocking position in which light is allowed to pass through the indicating device to the lens. U.'-S. Patent Application SN 08/327,202 (the '202 application), assigned to the assignee of the present invention, describes a cargo area lighting system for trucks using piped light. The *202 application discloses a light source mounted on the truck body and plural lighting fixtures mounted to the roof of the truck body. Each lighting fixture receives light which is piped through a separate light pipe from the source to the fixture. Two sets of lighting fixtures are disposed in linear arrays extending along a line from the front to the rear of the truck body. The light pipes for one set of lighting fixtures are all disposed within a first enclosure and the light pipes for the other set of lighting fixtures are all disposed within a second enclosure. Certain sections of the enclosures have transparent lenses and certain light pipes within the enclosures emit side light through those lenses. A lighting fixture at the rear door of the truck body has an optical switch for turning the lighting fixture on or off. A general object of this invention is to provide an improved lighting system for the cargo space of a truck which overcomes certain disadvantages of the prior art. SUMMARY OF THE INVENTION In accordance with this invention, an improved lighting system is provided for the cargo space of a truck body. The lighting system provides desired levels of illumination throughout the cargo space by using a piped light system which is highly efficient, simple and economical to install without intruding significantly into the cargo space and which requires little maintenance. By using light piped into the cargo space there is virtually no heat dissipation from the lighting system in the cargo space and therefore waste of energy in refrigerated truck bodies is avoided, as compared with incandescent lamps. Further, the risk of fire hazard from the lighting system is eliminated. In accordance with the invention, the lighting system for the interior of a truck body comprises an electrically energized light source mounted on the truck body, elongated enclosures which both support the light pipes along their lengths and which transmit laterally- emitted light from the light pipes into the cargo space. The enclosures include integral mounting flanges adapted to fasten the enclosure to one of the floor, side walls, front wall, rear wall and roof. The integral mounting flanges allow the light fixtures to be easily assembled into a new truck body or retrofit into the cargo space of an existing truck body. A complete understanding of this invention may be obtained from the detailed description that follows taken with the accompanying drawings. DESCRIPTION OF THE DRAWINGS FIGURE 1 is a partially cut-away cross- sectional schematic plan view of a third embodiment of the lighting system; FIGURE 2 is a partially cut-away cross- sectional schematic plan view of an alternative installation of the third embodiment of the lighting system; FIGURE 3 is a cross-sectional view of an enclosure of the embodiments of Figs, l and 2 taken along line 3-3 of either Figure 1 or Figure 2; and FIGURE 4 is a broken-out view of a light pipe of Figure 1 or 2. BEST MODE FOR CARRYING OUT THE INVENTION Referring now to the drawings, there is shown an illustrative embodiment of the invention in a truck body interior lighting system using piped light. It will be appreciated as the description proceeds that the invention may be used in other applications and may be realized in different embodiments. Figure 1 shows a trailer truck, generally shown at 10, having a cab and a truck body, generally indicated at 12 and 14, respectively. The truck body includes a floor 16, a roof 18, a front wall 22, side walls 24 and 24' and a rear wall 26. The truck body 14 encloses a cargo space which is refrigerated by a refrigeration unit 28. As shown in Fig. 2, the lighting system for the cargo space, in accordance with this invention, comprises at leaεt one light source 32 suitably mounted on the exterior of the front wall 22 above the refrigeration unit 28. A first embodiment of the lighting system, shown in Fig. 1, comprises two light sources 32A, 32B mounted on the exterior of the front wall 22 on either εide of the refrigeration unit 28. A second embodiment of the lighting system, shown in Fig. 2, comprises a single light source 32 mounted on the exterior of the front wall 22 above the refrigeration unit 28. Further, both the first and the second embodiments of the lighting system comprise two light pipes 38A, 38B, each of which extends from the light source to a point adjacent the back wall 26. Both the first and the second embodiments also include a pair of light pipe enclosures, generally indicated at 96 and 98, respectively, which each contain a single light pipe. The enclosure 96 includes enclosure sections 96A and 96B and the enclosure 98 includes enclosure sections 98A and 98B. The first embodiment of Fig. 1 shows enclosures 96 and 98 extending from two separate light sources, 32A and 32B, respectively. The second embodiment of Fig. 2 shows enclosure 96 extending from the same light source 32 as enclosure 98. The aforementioned components of the lighting system will now be described in greater detail. The light source 32 (32A and 32B in the second embodiment) comprises a high intensity lamp of the type described in the Robbins et al. patent 4,704,660 granted November 3, 1987. Such light sources are available from General Electric Company and Lumenyte International Corporation. Light sources of thiε type are commonly known as "light engines". The light source 32 is provided with a plurality of light ports each of which is adapted for optical coupling with a light pipe in a well-known manner. A light source is energized from the truck electrical system through an electrical conductor 46 which includes a manually actuable switch 48 mounted in the cab for operation by the driver. The light source includes a voltage inverter for developing a high voltage alternating current supply from the low voltage DC supply from the truck. The light pipes 38A and 38B are light conductors of the type constructed of polymeric material with a suitable cladding. The light pipes are preferably of the type known as solid core semi-rigid fiber optics such as that described in Zarian patent 4,957,347 granted September 18, 1990. Such light pipes are available from the Lumenyte International Corporation. The light pipes are commonly referred to individually as an "optic". The preferred light pipe for this invention is of a type identified as side-light fiber optic because it has the property of emitting light radially through the cladding around the core and also conducts light axially for emission through the end of the core (referred to herein as a side-fire/end-fire light pipe) . It will be understood that the lighting system of the first embodiment of this invention may also use light pipes extending between the light source and selected ones of the end-fire light fixtures which do not provide side light emission but instead emit light only from the output end (referred to herein as end-fire light pipes) . Each of the light pipes has an input end coupled with one of the ports of the light source and has an output end. As shown in Figs. 1, 2, 3 and 4, the elongated light pipe enclosures 96, 98 of the first and second embodiments are each disposed around and supporting one of the light pipes 38A, 38B. Each enclosure 96, 98 is formed in two elongated, approximate 12 foot segments 96A, 96B, 98A, 98B. The segments are disposed end-to- end in pairs, with a single light pipe 38A, 38B extending through each pair. All of the first and second embodiment enclosure sections 96A, 96B, 98A, 98B are of the same construction. Accordingly, description of only enclosure 96A will suffice and will be given with reference to Figure 3. As is best shown in Figure 3, the light pipe enclosure section 96A of the first and second embodiments includes a pair of elongated mounting flanges 100, 102 adapted to fasten each enclosure section into one of the upper corners formed where the side walls 24, 24' and roof meet. Enclosure section 96A is made of light transmissive material to allow laterally-emitted light from light pipe 38A to pass into the cargo space. The light transmissive material forms a light- transmitting panel 104 that is shaped to form a tubular conduit 106 for supporting the light pipe 38A. The conduit 106 includes an elongated longitudinally- oriented slot 108. To install light pipe 38A in enclosure section 96A, an inεtaller need only snap the length of light pipe 38A through the elongated slot 108 and into the tubular conduit 106. Mounting flanges 100, 102 project in radially opposite directions from one another and integrally extend from the tubular conduit 106 of each enclosure segment on opposite sides of the longitudinal slot 108. The flanges 100, 102 are bent, along their lengths, so that they extend outward at a right angle to one another. Enclosure section 96A is integrally extruded from a single piece of light-transmissive optical material so as to have an elongated shape of a uniform cross-section along its length. The tubular conduit 106 formed by the light-transmitting panel 104 includes a plurality of elongated parallel light-dispersion grooves 110. The grooves 110 perform the dual function of dispersing light, and hiding scratch marks that often form during the extrusion proceεs. The first and second embodiment light pipes 38A, 38B are of the same construction. Accordingly, description of only light pipe 38A will suffice and will be given with reference to Figure 4. Light pipe 38A includes a cladding with an index of refraction which causes the cladding to emit light laterally. As is best shown in Fig. 4, light pipe 38A includes angled cuts 112 disposed along its length. The cuts 112 have depths, angles & spacing optimized for even light distribution from along the length of light pipe 38A. An end mirror 114 is disposed at the output end 64 of light pipe 38A. The mirror 114 is positioned perpendicular to the central longitudinal axis of light pipe 38A. To operate the lighting system, the truck driver operates the electrical switch 48 to turn on the lighting system to illuminate the cargo space in the truck body. When the switch 48 is turned on the light sources 32A, 32B are energized and emit light from respective ports to the input ends of the light pipes 38A and 38B. Each light pipe 38A, 38B conducts light along its length while emitting light laterally through its respective enclosure sections 42A, 42B, 44A, 44B into the cargo space. Light is laterally emitted at a greater intensity at those points where diagonal cuts 112 are located. Light that is not laterally emitted is conducted to the output end 64 of each light pipe 38A, 38B and is reflected back into each light pipe 38A, 38B by mirrors 114, 116 so that no light is lost from the output ends 64. Although the description of this invention has been given with reference to a particular embodiment, it is not to be construed in a limiting sense. Many variations and modifications will now occur to those skilled in the art. For a definition of the invention reference is made to the appended claims.

Claims: What is claimed is: 1. A lighting system for a truck of the type having a cab for a vehicle driver and having a truck body for cargo, the body having cargo space enclosed by a floor, side walls, front and rear walls and a roof, said lighting syεtem comprising: an electrically energized light source mounted on the truck body; a light pipe having an input end and an output end and being adapted to transmit light received at said input end to said output end, said light pipe adapted to emit light laterally along its length, said light pipe input end being optically coupled to said light source for receiving light therefrom; and an elongated light pipe enclosure disposed around and supporting said light pipe, said enclosure comprising a mounting flange adapted to fasten εaid enclosure to one of said floor, side walls, front and rear walls and roof, said enclosure comprising a light transmitting panel disposed between said light pipe and the cargo space to transmit laterally-emitted light from said light pipe into the cargo space, said light transmitting panel compriεing an elongated conduit for εupporting said light pipe along its length. 2. A lighting syεtem as defined in Claim 1 wherein said light transmitting panel is formed into an elongated tubular shape defining said elongated conduit. 3. A lighting system as defined in Claim 2 wherein said conduit includes an elongated longitudinally-oriented slot for receiving said light pipe in force-fit snap-in engagement along itε length. 4. A lighting system as defined in Claim 1 wherein εaid light-transmitting panel includeε a plurality of elongated parallel light-dispersion grooves formed longitudinally along said conduit. 5. A lighting system as defined in Claim 1 wherein said enclosure compriseε at leaεt two elongated segments disposed end-to-end, said light pipe extending through both segmentε. 6. A lighting system as defined in Claim 5 wherein each said segment compriseε light transmissive material and where each said segment is integrally extruded from a single piece of said light transmissive material. 7. A lighting system as defined in Claim 1 wherein said light pipe includeε a cladding with an index of refraction which causes said cladding to emit light laterally thereof. 8. A lighting system as defined in Claim 1 wherein said light pipe includes angled cuts disposed along its length and where said cuts have depths, angleε & spacing optimized for even light distribution from along its length. 9. A lighting system as defined in Claim 1 wherein said light pipe output end is adapted to emit light from said output end and where said lighting system includes an end mirror dispoεed adjacent said light pipe output end, said mirror positioned to reflect light from said output end back into said light pipe. 10. A lighting system as defined in Claim 1 including an electrical energizing circuit extending from the cab to said light source; and a manually actuated switch electrically connected in said circuit and mounted in the cab for operation by the driver for turning said light source on or off.

Inventors: DEALEY ONWARD K JR, DOMAS BEN V, MCCAULEY ALVIN D, DEALEY, ONWARD, K., JR., DOMAS, BEN, V., MCCAULEY, ALVIN, D.
Applicants: TRANSMATIC INC, TRANSMATIC, INC.
Application year: 1996
Main classification: B60Q3
IPC codes: B60Q3