COOLING SYSTEM FOR THE CYLINDER HEAD AND THE TURBOCOMPRESSOR OF A CUMBUSTION ENGINE

Abstract: A cooling system for the cylinder head, the inlet manifold and/or the bearings of a turbo-compressor of a combustion engine with a liquid cooling circuit with a radiator, a thermostat and an electric fan as well as a circuit for the cooling of said cylinder head, the inlet manifold wherein the cylinder head and/or the inlet manifold and/or the bearings of a turbo-compressor to be cooled are incorporated in a circuit (11) which is connected in series or parallel to the part of the engine liquid cooling circuit (6) between the cylinder head of the engine block (1) and the radiator (7).

Description: The invention relates to a cooling system for the cylinder head and the turbo-compressor of a combustion engine, the cooling system having a liquid cooling circuit incorporating a main circuit with a coolant pump for the cooling of the cylinder head, a thermostat and a radiator with an electric fan, the radiator being connected via a passage to the thermostat, and further incorporating a supplementary circuit with an electrically driven coolant pump, the passage being provided with a non-return valve for preventing backflow of liquid through the passage when the electrically driven coolant pump is activated, the supplementary circuit at the downstream side being connected to the radiator. Such a cooling system is known from DE-A-2, 631, 121. This known system has a cooling liquid output with temperature sensors to which a bypass circuit is provided to bypass the passage wherein a three-way thermostat and the non-return valve are connected in series. The bypass circuit contains a series arrangement of the electric coolant pump and an other three-way thermostat. These three-way thermostats are of a type, that in dependence on the local cooling fluid temperature switch an input way, either to the second or to the third way. This known system is complex and for cooling of a combustion engine only. It is an object of the present invention to provide a simple and special designed cooling system for a combustion engine with at least one of two means consisting of means for cooling an inlet manifold with injectors and means for cooling a bearing means of a turbo-compressor, whereby in particular an efficient cooling of these means is archieved in operating conditions, while at the same time the possibility is created to maintain cooling of these means in an efficient way after the engine is switched off. Thereto the cooling system according to the invention is characterized in that the cooling system further has at least one of two means consisting of means for cooling an inlet manifold with injectors and means for cooling a bearing means of a turbo-compressor, that the means for cooling an inlet manifold with injectors is incorporated in the liquid cooling circuit and that the means for cooling a bearing means of a turbo-compressor is incorporated in the supplementary circuit, and that the supplementary circuit is connected at the upstream side to the thermostat. It is known per se from JP-A-60-261 931 to have a cooling water system having an engine, a radiator, a selector valve and a turbo-supercharger with bearings. The supercharger is selectively connectable in series with a bypass having an electrically driven coolant pump, the bypass being connected in parallel to the selector valve, whereby the pump and the valve are electrically controllable dependent on the temperature in the vicinity of the bearings in the supercharger and on a stopping signal from a rotational speed-detecting sensor in the engine. The cooling system according the invention provides an efficient cooling of in particular the inlet manifold means with injectors and/or the bearing means of the turbo-compressor regardless whether the engine is running or not. Also so called hot starting problems both with engines with a turbo-compressor and with those without one, will no longer cause problems. In a very simple embodiment of the cooling system according to the invention, the system is characterized in that the supplementary circuit has a temperature switch incorporated therein, which puts the electrical coolant pump into operation at an exit temperature of the liquid from the means for cooling the bearing means of a turbo-compressor of over approximately 100°C. The invention will now be explained with reference to a drawing which diagrammatically illustrates the entire cooling system. The figure diagrammatically illustrates an engine block 1, coolant being fed to the engine block at 2 by means of a mechanical coolant pump 3 and being discharged from the cylinder head part at 4 via a thermostat 5. The liquid discharged is led to a radiator 7 via a hose 6, cooled in said radiator, with the aid of an electric fan 8 if desired and, having been cooled, led back to the engine block 1 again via hose 9. The fan 8 is switched on by a thermo contact 10, which is also set to the temperature to be allowed of the supplementary circuit to be described hereinafter. According to the invention a supplementary circuit 11 is connected behind the thermostat 5, incorporated in which the circuit are an electric coolant pump 12 and the turbo-compressor 13 to be cooled. The circuit 11 opens into the radiator at 14 near the thermo contact 10. In the circuit 11, behind (in the direction of flow) the turbo-compressor 13, there is incorporated a temperature switch 15 which puts the coolant pump 12 in the same circuit into action at approx. 100°C and out of action at approx. 95°C. For the sake of completeness the drawing also illustrates an expansion tank 16 with connecting pipes (hoses) 17 and 18. Characteristic for the invention is the temperature switch 15, which co-operates with the electric coolant pump 12, whether the engine is running or not. The same applies to the thermo contact 10, which also co-operates autonomously with the fan 8, with regard to the temperature of the coolant of both the engine and the turbo-compressor. Essential for the purpose aimed at, viz. reducing the temperature level of the cylinder head, the inlet manifold with injectors and the turbo bearings without the disadvantages mentioned, by quick cooling, is a non-return valve 19 preferably forming part of the radiator 7. Essential in relation to the known state of the art is that positive use is made of the radiator (7), possibly aided by the fan (8) for the cooling of the cylinder head, the inlet manifold with injectors and the bearings of the turbo-compressor, whereby the non-return valve and the other means mentioned are indispensable. The supplementary circuit according to the invention is connected both parallel and in series to the normal cooling circuit. When the engine is running the circuit is parallel. With an opened thermostat the coolant flows partly direct to the radiator and partly via the supplementary circuit. With a switched-off engine there is a series circuit, because alle coolant flows via the supplementary circuit.

Claims: Cooling system for the cylinder head and the turbo-compressor of a combustion engine, the cooling system having a liquid cooling circuit incorporating a main circuit with a coolant pump (3) for the cooling of the cylinder head,a thermostat (5) and a radiator (7) with an electric fan (8), the radiator (7) being connected via a passage (6) to the thermostat (5), and further incorporating a supplementary circuit (11) with an electrically driven coolant pump (12), the passage (6) being provided with a non-return valve (19) for preventing backflow of liquid through the passage (6) when the electrically driven coolant pump (12) is activated, the supplementary circuit (11) at the downstream side being connected to the radiator (7) characterized in that the cooling system further has at least one of two means consisting of means for cooling an inlet manifold with injectors and means for cooling a bearing means of a turbo-compressor (13), that the means for cooling an inlet manifold with injectors is incorporated in the liquid cooling circuit and that the means for cooling a bearing means of a turbo-compressor is incorporated in the supplementary circuit (11), and that the supplementary circuit (11) is connected at the upstream side to the thermostat (5). Cooling system according to claim 1, characterized in that the supplementary circuit (11) has a temperature switch (15) incorporated therein, which puts the electrical coolant pump (12) into operation at an exit temperature of the liquid from the means for cooling the bearing means of a turbo-compressor of over approximately 100°C. Cooling system according to claim 1 or 2, characterized in that there is incorporated in the radiator (7) a thermo-contact (10), which can activate the electric fan (8) of the radiator (7), when the temperature of the coolant from the supplementary circuit (11) exceeds a certain value on entering the radiator (7). Cooling system according to claim 2 or 3, characterized in that at the presence of the temperature switch (15), the switch (15) is arranged to switch off the electrically driven coolant pump (12) at a coolant temperature below approximately 95°C.

Inventors: GOOSSENS, JAN JOHANNES, VEENEMANS, CORNELIS JOHANNES
Applicants: VOLVO CAR B.V.
Application year: 1987
Main classification: F01P7
IPC codes: F01P3, F02B39, F01P11, F01P7