Marine container roof structure with heat insulation

Abstract: A heat-insulated marine container has an elongate hexahedral shape and includes a roof, a floor confronting the roof, and corner members positioned at four corners of each of the roof and the floor. The marine container has a roof structure which comprises a roof (2) and an inner lining (3) panel which are bonded to the opposite surfaces of a heat insulation (4) sandwiched therebetween. At least one of the roof and the inner lining panel has a plurality of stress-­ absorbing corrugations (8). The corrugations extend longitudi­ nally or transversely of the marine container, and may have various cross-sectional shapes.

Description: The present invention relates to a marine container roof structure with a heat insulation, and more particularly to a marine container roof structure with a heat insulation, which structure is protected from damage during usage. Containers are in the form of simple transportation boxes whose outside surfaces are covered with metal panels, and widely used in many transport applications such as ship, railroad, and automobile transport systems. Among various containers are large-size marine containers used mainly for sea transport. One known marine container disclosed in US-A- 3,206,902 comprises a floor, a roof, and side walls each comprising a heat-insulated structural body which is composed of a heat insulation sandwiched between two metal panels. The roof structure of a marine container with a heat insulation will be described below with reference to the accompanying drawings. Fig. 6 of the accompanying drawings shows in fragmentary cross section a roof of a marine container which is in the form of a long rectangular parallelepiped (see Fig. 5) or a hexahedral shape, the view being taken along a longitudinal plane extending from the roof to the confronting floor of the container. As shown in Fig. 6; the roof of the marine container has a flat roof panel 2 and a flat inner lining panel 3 which are disposed upwardly and downwardly of transverse beams 1 spaced at intervals in the longitudinal direction of the container. The space between the roof panel 2 and the inner lining panel 3 is filled with a heat insulation 4. The container also includes side panels 11 extending downwardly from the side edges of the roof. The marine container, with cargo stored therein, is loaded from ground onto a ship or unloaded from a ship onto ground, by a container crane. As shown in Figs. 5 and 6, the marine container has corner members 5 on its corners which will be hooked for loading and unloading. More specifically, as shown in Fig. 5, fastening hooks 7 of a spreader 6 of a container crane are held in engagement with the respective corner members 5, and the marine container is lifted or lowered by the container crane through the spreader 6. When the marine container is suspended by the container crane, the container is largely flexed by a vertical interval 6 at its center due to the weight of the cargo stored in the container as illustrated in Fig.7. Therefore, the roof panel 2 of the marine container is subjected to a compressive load while the container is being suspended. Since the marine container is repeatedly used over a long period of time, the roof panel 2 undergoes repeated compressive loads when the container is loaded and unloaded, and hence will have localized metal fatigue regions or localized deformed regions. The localized metal fatigue regions produce cracks in the roof panel 2, or the localized deformed regions force the roof panel 2 to be peeled off the heat insulation 4 or rupture the heat insulation 4. The cracks in the roof panel 2 allow rainwater to enter into the container roof, and the peeling or rupture of the heat insulation 4 reduces the heat insulation capability thereof. In view of the aforesaid problems of the conventional heat-insulated marine container roof structure, it is an object of the present invention to provide a marine container roof structure with a heat insulation, which structure is capable of absorbing localized load irregularities or deviations which are caused in the roof when the container is loaded or unloaded. FR-A-2363050 discloses a roof structure for a heat-insulated marine container having an elongate hexahedral shape and including a roof, a floor confronting the roof, and corner members positioned at four corners of each of the roof and the floor, the roof structure comprising a heat insulation, a roof panel attached to a face of the heat insulation, an inner lining panel attached to a back of the heat insulation and plurality of stress-absorbing corrugations disposed on at least the roof panel, and according to the present invention such a roof structure is characterised in that the corrugations extend longitudinally of the container, and have a triangular cross-section. The stress-absorbing corrugations may be disposed on both the roof panel and the inner lining panel. The corrugations comprise ridges projecting outwardly from the roof, or grooves formed concavely inwardly into the roof. The corrugations are preferably spaced at pitches which are smaller in a region of the roof where produced stresses are larger. In the accompanying drawings:- Fig. 1 is a plan of a marine container roof structure according to the present invention; Fig. 2 is an enlarged sectional view taken along the line VII - VII of Fig, 1; Fig. 3 is a cross-sectional view showing a longitudinal ridge; Fig. 4 is a fragmentary perspective view of a modification of the marine container roof structure according to Figs. 1 to 3; Fig. 5 is a perspective view of a typical marine container and spreader for suspending the marine container; Fig. 6 is a fragmentary vertical cross-sectional view of a conventional marine container; and, Fig. 7 is a side elevational view showing the manner in which a roof panel of a marine container is flexed when the container is suspended. As shown in Fig. 1, the marine container roof structure includes a roof panel 2 bonded to the upper surface of a heat insulation. The roof panel 2 has two pairs of longitudinal ridges 80 respectively at lateral sides thereof and a single longitudinal ridge 80 at the centre. As shown in Fig. 2, the two pairs of longitudinal ridges 80 at the lateral sides are located inwardly of the lateral edges of the roof panel 2, leaving attachment margins along which the lateral edges of the roof panel 2 are fastened to upper side frames 9 by rivets 10. The longitudinal ridges 80 are of a triangular cross-section as shown in Fig. 3. As shown in Fig. 2, an inner lining panel 3 bonded to the lower surface of the heat insulation also has similar longitudinal ridges 80. Therefore, the upper and lower surfaces of the roof of the marine container are stiffened by the ridges 80, so that the marine container has an increased service life. In as much as the longitudinal ridges 80 are provided at the lateral sides and centre of at least the roof panel 2, irregular compressive loads applied to the roof which are produced when the marine container is suspended can be absorbed by the longitudinal ridges 80, and hence the roof panel 2 is prevented from being locally buckled. The longitudinal ridges 80 are also effective to absorb thermal strains in the roof. Therefore, any damage to the roof of the marine container due to compressive load irregularities and thermal strains is minimized, and the service life of the marine container is extended. Fig. 4 shows a modification of the marine container roof structure according to Figs 1 to 3. As shown in Fig. 4, a roof panel 2 has two pairs of longitudinal grooves 80′ respectively at lateral sides thereof and a single longitudinal groove 80′ at the centre. An inner lining panel 3 also has similar longitudinal grooves 80′. These longitudinal grooves 80′ in the roof panel 2 and the inner lining panel 3 are also effective in stiffening the upper and lower surfaces of the roof and hence increasing the service life of the marine container.

Claims: A roof structure for a heat-insulated marine container having an elongate hexahedral shape and including a roof (2), a floor confronting the roof, and corner members (5) positioned at four corners of each of the roof and the floor, the roof structure comprising a heat insulation (4), a roof panel (2) attached to a face of the heat insulation (4), an inner lining panel (3) attached to a back of the heat insulation (4) and a plurality of stress-absorbing corrugations (80,80′) disposed on at least the roof panel, characterised in that the corrugations (80,80′) extend longitudinally of the container, and have a triangular cross-section. A roof structure according to claim 1, wherein the stress-absorbing corrugations (80,80′) are disposed on both the roof panel (2) and the inner lining panel (3). A roof structure according to claim 1 or claim 2, wherein the corrugations comprise ridges (80) projecting outwardly from the roof. A roof structure according to claim 1 or claim 2, wherein the corrugations comprise grooves (80′) formed concavely inwardly into the roof. A roof structure according to any one of the preceding claims, wherein the corrugations (80,80′) are spaced at pitches which are smaller in a region of the roof where produced stresses are larger.

Inventors: HIROSE HIROSHI, UCHIKOSHI MICHINOBU, HIROSE, HIROSHI, UCHIKOSHI, MICHINOBU
Applicants: FRUEHAUF JAPAN, NIPPON FRUEHAUF COMPANY LIMITED
Application year: 1990
Main classification: B65D90
IPC codes: B65D90, B65D88