Cooling system for cooling a liquid coolant in an immersible motor vehicle
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a cooling system for cooling a liquid coolant in an immersible motor vehicle, particularly to a cooling system for a floatable or submersible motor vehicle having a liquid-cooled engine, wherein a radiator is accommodated in a chamber, which is flown through by air during land travel and admits water when the vehicle is submerged or floating. 
     2. Description of the Prior Art 
     A known cooling system of that kind has been disclosed in Published German Application No. 1,804,607. In that known system, the chamber which accommodates the radiator is disposed above the engine, and the radiator and fan are disposed in said chamber one beside the other under a grating. Openings which are adapted to be closed by valve flaps are provided on opposite sides of the chamber and communicate with the engine-transmission compartment. During land travel, the two valve flaps are open and the fan sucks part of the air directly via a short circuit and causes another part of the air to flow through one opening of the chamber and around the engine-transmission assembly and through the other opening. When the vehicle is floating or submerged and the two valve flaps are closed so that liquid is not admitted to the engine-transmission compartment and only the chamber above said compartment is flooded. That known cooling system has various disadvantages. As the vehicle is immersed into the water, the chamber which accommodates the radiator and the fan is entirely filled with water so that the overall weight of the vehicle is considerably increased and its ability to float is reduced to some extent. If the entire assembly is not centered in the vehicle but is laterally offset, the vehicle may become overbalanced toward one side so that it assumes an oblique position. It will also be unfavorable to expose the fan to the entering water. Special measures must be adopted to ensure that the water will be drained out of the chamber when the vehicle has surfaced. It will obviously impossible to cool the radiator for the engine with both air and water when only part of the pan is immersed. 
     SUMMARY OF THE INVENTION 
     For this reason it is an object of the invention to eliminate said disadvantages and so to improve the cooling system described first hereinbefore that the buoyancy will be only slightly decreased and any displacement of weight occurring when the vehicle is floating or submerged will be only small, and that the space requirement will be only slightly larger than that of a radiator which is cooled only by air. The latter aspect is of special importance is small vehicles. 
     The object set forth is accomplished in accordance with the invention in that the chamber contains a partition, by which the heat exchange surfaces of the radiator are divided into two sections at least on the cold side, an air supply duct opens into one, preferably larger, compartment, which is disposed on one side of the partition, said one compartment is provided with flow passages which lead to the outside and are all adapted to be closed, and the other compartment is adapted to be shut off from said one compartment and is preferably smaller and is adapted to be flooded alone. 
     Owing to that arrangement said one compartment, which is preferably larger, is sealed and will not admit water when the vehicle is floating or submerged. Only the smaller compartment is flooded so that the increase in weight and the above-described results of such increase will be only small. The invention is based on the recognition that the heat exchange surface area which is required for a cooling of the liquid coolant for the engine by the external water will be much smaller than the heat exchange surface area which is required when said the heat exchange surfaces are cooled by the air which is delivered by the fan. As a result, both compartments are supplied with air during land travel and only the smaller compartment is flooded during travel on or in water. Owing to the provision of the partition and the possibility to shut off the two compartments from each other, a combined cooling can be effected under certain conditions of travel in that the radiator for cooling the engine is cooled only with air in one compartment and only with external water in the other compartment. Because the air supply duct opens only into that compartment which is adapted to be shut off from the outside, the fan will not be contacted by water so that a simple fan can be used and special sealing measures need not be adopted. It will be understood that the radiator need not be used to cool the liquid coolant for the engine but the radiator may alternatively communicate with an oil cooler or with a charge air cooler. 
     The partition may consist of a closed box and the open ends of tubes which constitute the two sections of the heat exchange surfaces may be sealed in the broadside walls of said box. That arrangement will result in a particularly simple radiator structure in which the entire coolant is cooled in the flooded compartment during travel on or in water. Alternatively, the partition may be parallel to the tubes which constitute the radiator and which are preferred connected in parallel. In that case only those tubes which extend through the flooded compartment will be used for a heat exchange when the vehicle is floating or submerged. 
     The flooding of one compartment, which is preferably the smaller compartment, might by effected by a mere communication through a low-level supply pipe as the vehicle is immersed. In order to ensure that the compartment will be flooded quickly, the floodable compartment is connected to the discharge line from a water pump and is provided with a water drain. 
     In accordance with the invention a valve flap is provided for shutting off the floodable compartment from the other compartment and said valve flap in an open position serves as an air-guiding wall and optionally closes the pump discharge line and/or the water drain at the same time so that said valve flap has a dual function. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a vertical sectional view showing those components of the cooling system which are essential for the invention. 
     FIG. 2 is a similar view showing a modified cooling system. 
     FIG. 3 is a transverse sectional view showing a portion of the radiator with the partition. 
     FIG. 4 is an elevation showing a different radiator and 
     FIG. 5 is an associated transverse sectional view taken on line V--V in FIG. 4. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention is illustrated strictly diagrammatically and by way of example on the drawing. 
     A radiator 1 for a liquid-cooled engine, not shown, of a motor vehicle which is adapted to float and/or dive is accommodated in a chamber 2 provided in the body 3 of the motor vehicle. During land travel, cooling air is supplied to the chamber 2 by a fan V and said air enters the body 3 of the vehicle through an opening, not shown, which is formed in said body. Said air is sucked by the fan and leaves the chamber 2 through an opening, which is protected by gratings 4. The chamber 2 contains a partition 5, by which the heat exchange surfaces of the radiator 1 are divided into two sections at least on the cold side. The air supply line 6 opens into a larger compartment 2a, which is disposed on one side of the partition and is provided with flow passages 8, which lead to the outside and are adapted to be closed by valve flaps 7. The smaller compartment 2b is adapted to be shut off from the compartment 2a by a valve flap 9 and is connected to the discharge line 10 coming from a water pump 11 and is provided with a water drain 12. When the vehicle is submerged or floating, the larger compartment 2a is shut off against an ingress of water and only the smaller compartment 2b is flooded. 
     The design shown in FIG. 2 differs from that shown in FIG. 1 in that the radiator 1 is substantially vertical and the compartment 2b is provided with two shut-off valve flaps 9. The shut-off valve flaps 9 may be so designed and arranged that in an open position they constitute an air-guiding wall for the cooling air which flows also through the compartment 2b during land travel and that they close the discharge line 10 from the pump and/or the water drain 12 at the same time. 
     In accordance with FIG. 3 the partition 5 consists of a closed box and the open ends of tubes 1a, which constitute the two sections of the heat exchange surfaces, are sealed in the broadside walls 5a of the partition 5. Alternatively, the partition 5 may be parallel to the tubes 1a which constitute the radiator and which are preferably connected in parallel, as is apparent from FIGS. 4 and 5.