Heat storage means

A heat storage means, and more particularly to a latent heat storage means for motor vehicle heating systems supplied by engine waste heat, comprises an inner container (10) with a storage core within it, an outer container (12) surrounding the inner container with a clearance with the formation of a preferably evacuated insulating space (14) and two ducts (16 and 18) extending through the insulating space (14), of which one duct serves as a supply duct and of which the other serves as a return duct for a heat vehicle fluid and both are arranged adjacent to the insulating space (14) in such a manner that they have a straight section (16b and 18b) which is as long as possible. The cross section of such duct sections has such a dense arrangement of permanently fitted elements running in the direction of flow that the periphery contacted by the fluid is, in comparison with the flow cross section, so large that convection is substantially prevented.