Abstract:
A cooling system for an internal combustion engine with at least two cylinder rows, in particular for a V-engine for a motor vehicle, has a coolant radiator and a thermostat valve for controlling a flow of coolant from coolant outlets of the cylinder rows, through or bypassing the coolant radiator, and back to the coolant inlets of the cylinder rows. The coolant outlet of one of the cylinder rows is directly connected with an inlet of the coolant radiator, and the coolant outlet of another cylinder row is directly connected with a bypass inlet of the thermostat valve. A bi-directional intermediate line is arranged between the bypass inlet of the thermostat valve and the inlet of the coolant radiator.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of German Patent Application Ser. No. 101 27 219.7, filed May 23, 2001. 
     FIELD OF THE INVENTION 
     The invention relates to a cooling system for an internal combustion engine that has at least two cylinder rows, such as a V-engine for a motor vehicle. The coolant system includes a coolant radiator and a thermostat valve for controlling the amount of coolant flowing from the coolant outlets of the cylinder rows through the coolant radiator, or through a bypass around the coolant radiator, and back to the coolant inlets of the cylinder rows. 
     BACKGROUND OF THE INVENTION 
     Internal combustion engines that have at least two cylinder rows require an increased coolant conducting capacity, because the coolant flowing from each of the cylinder rows must be combined at a point upstream of the coolant radiator in order to permit the coolant to be conducted either through the coolant radiator or through a bypass line. When the coolant is conducted transversely through the cylinder heads of a V-engine that has been installed in the direction of travel (as of a vehicle), and the coolant radiator is installed transversely to the direction of travel, it has heretofore been necessary for structural reasons to conduct the coolant through an elaborate system of conduits in order to achieve an appropriate coolant flow rate, particularly with respect to the combination of coolant flowing from each cylinder row. What is needed, therefore, is a cooling system wherein the coolant flow path is simplified and the requirement of increased coolant conducting capacity is lessened. 
     OBJECT AND SUMMARY OF THE INVENTION 
     It is accordingly an object of the present invention to provide a cooling system whose working volume is reduced, which permits the design of the coolant conduit system to be simplified, and which permits the flow path of coolant to be as straight as possible. 
     This object is achieved in the present invention, a cooling system for an internal combustion engine with at least two cylinder rows, such as and particularly a V-engine. The cooling system has a coolant radiator and a thermostat valve for controlling the amount of coolant flowing from the coolant outlets of the cylinder rows through the coolant radiator or through a bypass around the coolant radiator, and back to the coolant inlets of the cylinder rows. In the present invention, the coolant outlet of one of the cylinder rows is directly connected with the inlet of the coolant radiator, the coolant outlet of another of the cylinder rows is directly connected with the bypass inlet of the thermostat valve, and an intermediate, bi-directional coolant line is present between the bypass inlet of the thermostat valve and the inlet of the coolant radiator. 
     Depending on the way in which the thermostat valve is set, a portion of the coolant can be allowed either to flow through or to bypass the coolant radiator by changing the direction in which the coolant flows through the intermediate line. Since only that portion of the amount of coolant flowing from one cylinder row flows through the intermediate line, less coolant is needed than in a conventional cooling system, the time required to “warm up” the engine (i.e., for the coolant to reach its optimum temperature) is reduced, and the coolant line leading from the outlet to the thermostat valve may be given a partially reduced cross-section. Moreover, the simplified arrangement of the coolant circuit makes it possible to shorten and straighten the lines leading from the outlet to the radiator and from the radiator to the inlet. This yields a particular advantage when the coolant circuit is designed so that the coolant flows transversely through the cylinder heads of a longitudinally installed V-engine, since, in conventional cooling systems, designing a transverse flow requires a long and complicated line course. 
     In connection with a further development of the invention, the intermediate line runs directly along the engine housing, thereby permitting space to be saved. Additionally, the intermediate line is advantageously integrated into a distributing component attached to the engine housing. In such an arrangement, it is not necessary to extend hoses close to the engine, and the required structural space is reduced. 
     In still a further development of the invention, a coolant pump is disposed between two cylinder rows, and the thermostat valve is advantageously arranged in the area of the coolant outlet of one of the cylinder rows. A connecting line between the thermostat valve and the coolant pump may be advantageously integrated into the distributing component. These measures result in further space savings. 
     In another development of the invention, two separate coolant circuits, substantially as described above, are provided, one for the cylinder heads and one for the engine blocks, and at least one of the coolant circuits has an intermediate line between two coolant outlets. In connection with such a so-called “split” cooling system having two coolant circuits, the reduced content of the lines is of particular importance. Also, straight, space-saving lines are particularly important with two coolant circuits. 
     In yet another development of the invention, the intermediate lines are integrated into a distributing component disposed on the engine housing. A pair of coolant lines connecting the thermostat valves to the coolant pumps of the coolant circuits are likewise advantageously integrated into the distributing component. 
     These measures result in a substantial space savings, and because the lines are integrated into the distributing component disposed on the engine housing, the number of separate hose connections in the cooling system may be substantially reduced. Moreover, only the distributing component, and not the engine housing, must be changed if a change in the external coolant circuits is desired. 
     In still a further development of the invention, the respective thermostat valves of the two coolant circuits are arranged so as to be offset from and next to each other in the longitudinal direction of the internal combustion engine. This enables the fines leading thereto to be crossed more easily, while maintaining or improving the reduction in space requirements. 
     In yet another development of the invention, the distributing component is made in a single piece, with at least one section of a housing of the thermostat valve integrated into the distributing component. The one-piece design of the distributing component in particular helps to avoid the problem of sealing the connection between the housing and any coolant lines. For example, the distributing component can be produced as an injection-molded plastic part. 
    
    
     BRIEF DESCRIPTION OF THE INVENTION 
     Further characteristics and advantages of the invention ensue from the claims and the description in connection with the drawings, wherein: 
     FIG. 1 is a schematic view of a conventional cooling system for a V-engine; 
     FIG. 2 is a schematic top view of a cooling system according to the present invention for a V-engine in accordance with a first preferred embodiment; 
     FIG. 3 is a schematic front view of a V-engine with a cooling system as in FIG. 2; 
     FIG. 4 is a schematic top view of a cooling system according to the present invention in accordance with a second preferred embodiment; 
     FIG. 5 is a schematic front view of a V-engine with a cooling system as in FIG. 4; and 
     FIG. 6 is a schematic top view of a distributing component according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, a conventional cooling system is shown wherein a longitudinally installed V-engine with a right cylinder row  10  and a left cylinder row  12  (relative to the direction of travel) is cooled by means of a radiator  14 . The cooling system has a coolant pump  16 , as well as a thermostat valve  18 . 
     When the thermostat valve  18  is in a first position, coolant is conducted from the coolant pump  16  through the cylinder rows  10 ,  12  (longitudinally in the direction of travel), through the coolant radiator  14 , through the thermostat valve  18  and back to the coolant pump  16 . In a second, bypass position, the coolant is conducted so as to bypass the radiator  14 , from the coolant pump  16  through the cylinder rows  10 ,  12 , through the thermostat valve  18 , and back to the coolant pump  16 . 
     As the coolant exits from the cylinder rows  10 ,  12 , the coolant lines are brought together. Starting at the coolant outlet from the cylinder rows  10 ,  12 , and up to the inlet into the radiator  14 , it is necessary for the total flow cross-section to provide for the entire flow in both cylinder rows  10 ,  12 . Likewise, the bypass line leading from the thermostat valve  18  to the coolant pump  16  must have sufficient capacity to handle the entire flow cross-section. 
     Referring now to FIG. 2, a first preferred embodiment of the cooling system of the present invention is shown in schematic format. For comparison purposes, those components depicted in FIG. 2 that have the same function as those in the conventional cooling system as in FIG. 1 have been provided with the same reference numerals. In a cooling system in accordance with the present invention in FIG. 2, however, the flow of coolant through the cylinder rows  10 , 12  is transverse with respect to the direction of travel. This arrangement is desirable because the cylinders may be cooled more evenly, which permits more even wear. 
     In the cooling system depicted in FIG. 2, the coolant flows through the coolant pump  16  and through the left and right cylinder rows  10 ,  12 . If the thermostat valve  18  is positioned to block an outlet line  20  of the radiator  14 , coolant flows from the coolant outlet  22  of the right cylinder row  10  through an intermediate line  24  to the bypass inlet of the thermostat valve  18 . From the left cylinder row  12 , coolant flows from a coolant outlet  26  to the bypass inlet of the thermostat valve  18 . From the thermostat valve  18 , the coolant is directed through connecting line  28  to the coolant pump  16 . Thus, no coolant flows through the coolant radiator  14  when the thermostat valve  18  is in the bypass position. One half of the entire coolant flow, specifically the coolant flow originating at the cylinder row  10 , flows through the intermediate line  24 . 
     After the coolant has been sufficiently heated in the coolant circuit, the thermostat valve  18  assumes a second position, at which the outlet line  20  coming from the radiator  14  is opened and the bypass inlet of the thermostat valve  18  is closed. For the sake of a simplified representation, only the extreme positions of the thermostat valve  18  will be explained, but intermediate positions are also possible. In this second position of the thermostat valve  18  coolant flows, starting at the coolant pump  16 , through the right cylinder row  10  and from the coolant outlet  22  to the coolant radiator  14 . The coolant flowing through and exiting the left cylinder row  12  through coolant outlet  26  flows through the intermediate line  24  (albeit in the opposite direction from the bypass phase) and reaches the inlet of the coolant radiator  14 . Thus only one half of the coolant flow, specifically the coolant flow emanating from the left cylinder row  12 , passes through the intermediate line  24 . The entire coolant flow reaches the thermostat valve  18  through the outlet line  20  of the coolant radiator  14  and is conducted through the connecting line  28  back to the coolant pump  16 . 
     Depending on the position of the thermostat valve  18 , a portion of the entire coolant flow flows in one direction or the other through the intermediate line  24 . It is already possible to determine from the schematic representation in FIG. 2 that because of this arrangement it is possible to place the coolant lines quite directly between the coolant outlets  22 ,  26  and the radiator  14 , or the thermostat valve  18 , because the coolant outlet  22  is directly connected with the inlet of the radiator  14 , and the coolant outlet  26  directly with the bypass inlet of the thermostat valve  18 . Since only one half of the total coolant flow ever passes through the intermediate line  24 , intermediate line  24  may have a reduced cross-section with respect to conventional systems. For instance, in comparison with the conventional cooling system in FIG. 1, in which each line must be able to handle the entire amount of coolant flow, the amount of coolant in the lines is reduced, and the warm-up phase is shortened. 
     So that an even flow passes through both cylinder rows  10 ,  12 , it is possible, for example, to employ baffles or different line cross sections. A heater  29  for the passenger compartment, or an oil cooler, can be integrated into the cooling system. The thermostat valve  18  can also be designed in such a way that at low numbers of revolutions the thermostat valve  18  at least partially blocks a bypass by means of a spring in order to improve the flow through the heater  29 . As can be seen from the above description, the intermediate line  24  can be directly connected with the coolant outlets  22 ,  26  at the cylinder rows  10 ,  12 , or with the lines originating at the coolant outlets  22 ,  26 , or directly with the bypass inlet of the thermostat valve  18  and the inlet into the radiator  14 . 
     A front view of a V-engine with a cooling system in accordance with a first preferred embodiment of the invention, such as is schematically illustrated in FIG. 2, is shown in a schematic front view in FIG.  3 . The V-engine has, as viewed in the direction of travel, a right cylinder row  10  and a left cylinder row  12 . The V-engine has been installed in the longitudinal direction behind a vehicle radiator  14 . The right cylinder row  10  has a coolant outlet  22 , and the left cylinder row  12  has a coolant outlet  26 . The intermediate line  24  extends along the engine housing of the V-engine in front of the ends of the cylinder rows  10 ,  12  facing the radiator  14 . The intermediate line  24  connects the coolant outlets  22  and  26  of the cylinder rows  10 ,  12 . 
     The thermostat valve  18  is arranged in the area of the coolant outlet  22  of the cylinder row  10 . The coolant pump  16  is arranged between the cylinder rows  10 ,  12 . The connecting line  28  from the thermostat valve  18  to the coolant pump  16  runs in front of the end of the cylinder row  10  facing the radiator  14 . 
     Connecting line  28  and intermediate line  24 , are preferably integrated into a distributing component  32 , which is disposed on the engine housing in front of the ends of the cylinder rows  10 ,  12  facing the radiator  14 . The shape of distributing component  32  will depend largely upon the shape of the engine housing to which it is mounted, but will preferably be formed in a plate shape with the coolant lines integrated therein. In this manner it is possible to arrange the connecting line  28  and the intermediate line  24  to save space within the engine compartment without employing separate flexible hoses. 
     Referring now to FIG. 4, a second preferred embodiment of a cooling system according to the present invention is depicted schematically. The cooling system has been embodied as a so-called “split” cooling system and includes two separate cooling circuits, one for the cylinder heads and one for the cylinder blocks of the cylinder rows  10 ,  12 . The engine represented has, as viewed in the direction of travel, a right cylinder row  10  with a cylinder head  34  and a cylinder block  36 , and a left cylinder row  12  with a cylinder head  38  and an engine block  40 . The components of the cooling circuit assigned to the cylinder heads  34 ,  38  are identified by a capital letter A, and the components of the cooling circuit assigned to the cylinder blocks  36 ,  40  are identified by a capital letter B. 
     The coolant circuit assigned to the cylinder heads  34 ,  38  has a coolant pump  16 A, from which coolant flows to cylinder heads  34 ,  38 . An intermediate line  24 A connects a coolant outlet  42  of the right cylinder head  34  with the coolant outlet  44  of the left cylinder head  38 . The coolant outlet  42  is directly connected with the inlet of the radiator  14 A, and the coolant outlet  44  is directly connected with a bypass inlet of the thermostat valve  18 A. Depending on the position of a thermostat valve  18 A, a portion of the entire coolant flow passes in opposite directions through the intermediate line  24 A, and the entire coolant flow either reaches a coolant radiator  14 A or, in bypass mode, the coolant pump  16 A directly via the thermostat valve  18 A. 
     In the coolant circuit assigned to the engine blocks  36 ,  40 , the coolant flows to the cylinder blocks  36 ,  40  from a coolant pump  16 B. An intermediate line  24 B connects a coolant outlet  46  of the right cylinder block  36  with a coolant outlet  48  of the left cylinder block  40 . The coolant outlet  46  is directly connected with an inlet of the radiator  14 B, and the coolant outlet  48  is directly connected with a bypass inlet of the thermostat valve  18 B. Depending on the position of a thermostat valve  18 B, either the coolant flow emanating from the cylinder block  36  reaches the thermostat valve  18 B via the intermediate line  24 B, or the coolant flow emanating from the left cylinder block  40  reaches a coolant radiator  14 B via the intermediate line  24 B. When the system is in a full cooling mode, the whole of the coolant flow is directed through the coolant radiator  14 B to thermostat valve  18 B, and from there back to the coolant pump  16 B. When the system is in a full bypass/warm-up mode, the entire coolant flow bypasses the coolant radiator  14 B and reaches the coolant pump  16 B directly. In addition to the extreme positions, a part-bypass, part-cooling mode occurs when the thermostat valve is in an intermediate position corresponding with different portions of the coolant flows. For example, at a low number of revolutions, the thermostat valve  18 B can block a bypass at least partially in order to improve the flow through a heater or to prevent coolant from flowing through the cylinder blocks  36 ,  40  in a warm-up phase, so as to save fuel. 
     Referring now to FIG. 5, a schematic front view illustrates a V-engine with a cooling system according to the second preferred embodiment of the present invention as in FIG.  4 . The V-engine is arranged in the longitudinal direction behind coolant radiators  14 A and  14 B. As can be seen in FIG. 5, the present invention enables the coolant lines leading from the coolant outlets  44 , 48  to the coolant radiators  14 A,  14 B, or those leading from the coolant radiators  14 A,  14 B to the thermostat valves  18 A,  18 B, to be shorts and relatively straight. 
     Coolant pumps  16 A,  16 B are assigned to the cylinder heads and blocks, respectively, and are preferably disposed between the cylinder rows of the V-engine. This arrangement permits intermediate lines  24 A,  24 B and connecting lines  28 A,  28 B to run parallel to each other, without requiring a crossover. Intermediate lines  24 A,  24 B and connecting lines  18 A,  28 B can consequently be integrated into a common, flat distributing component  50 , which has been only schematically indicated in FIG. 5 by a dashed line. In a preferred embodiment, the distributing component  50  is plate-shaped and is disposed directly on the engine housing of the V-engine in front of the ends of the cylinder rows facing the radiators  14 A,  14 B. The use of distributing component  50  permits the present invention to be implemented without flexible hose connections, and with a more pleasant, smooth-surface design. 
     Referring now to FIG. 6, a distributing component  52  is depicted schematically from above. In order to ease a crossover of connecting lines  28 A,  28 B, the thermostat valves  18 A,  18 B are arranged, one behind another, in an offset and adjacent relationship in the longitudinal direction  54  of an engine. Additional coolant lines in the distributing component  52  are indicated in phantom. The sections of the housings of the thermostat valves  18 A,  18 B, from which coolant lines such as connecting lines  28 A,  28 B emanate, are integrated into the distributing component  52 . The distributing component is therefore producible in one piece, for example, by plastic injection molding. 
     In view of the aforesaid written description of the present invention, it will be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications, and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to preferred embodiments, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended nor is to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.