INDEPENDENT COOLING SYSTEM FOR INTERNAL COMBUSTION ENGINES

Abstract: The present invention refers to an independent cooling system intended to internal combustion engines. Such system consists of: a) a cylinder-head (1) independent cooling subsystem within which the coolant flows from an expansion and filling reservoir (6), is pumped by a coolant pump (2) to perform the coolant forced flow to a primary radiator (4) and to the cylinder head (1). By means of a coolant temperature sensor (5), a control module (10) measures the coolant temperature in a determined location, making possible the accurate control of the operation of the system; b) an engine block (7) independent cooling subsystem, within which the coolant flows naturally (free convection) from an expansion and filling reservoir (9) to an independent secondary radiator (8) and to the engine block (7).

Description: "Independent Cooling System for Internal Combustion Engine Application Area This invention refers to an independent cooling system designed to cool, vehicular or stationary, internal combustion engines which operate with coolant in a closed-circuit system. The invention is characterized by performing the engine cooling through two independent closed-circuit subsystems. One of these two subsystems performs the engine cylinder-head cooling. The other one performs the engine block cooling. Background of the invention The current vehicular engine's cooling systems, basically, consist of a single radiator that exchanges heat between the whole coolant existent in the vehicle's engine cooling system (engine block plus cylinder head, hoses, radiator, etc.) and the surrounding air. In such a system, the engine block and cylinder head constitute a part of the flowing circuit, within which the engine block coolant and the cylinder head coolant mix, and vice- versa. Whenever the thermostatic valve is closed (opening temperature not reached), a mechanical pump generates the coolant flow between the engine block and the cylinder head only. As the thermostatic valve starts its opening process (the opening temperature was surpassed), coolant flow occurs inside the whole engine cooling system. The coolant pump continuously absorbs a fraction of the engine power output. In the current systems, there is no precise mass flow rate and coolant temperature control. A substantial amount of the engine power output is wasted by the coolant pump, due to the gross nature of the current system control. The coolant volume in the system is considerably high. In the independent cylinder head cooling subsystem, according to the present invention, the correspondent flow circuit consists of the following components: cylinder head, electric or electromechanical coolant pump (to generate forced flow in the system), flow-controlling valve (to control the flow rate in the closed circuit), an independent primary radiator (to exchange heat with the surrounding ambient), a coolant temperature sensor (to measure the coolant temperature in a specific position in the flow circuit, and to make possible the control of the system's operation ), and an expansion and filling reservoir. In the independent reservoir engine block cooling subsystem, according to the present invention, the respective coolant flow circuit consists of the following components: engine block, an independent secondary radiator (to exchang the surrounding ambient), and an expansion and filling reservoir. The independent cooling system for internal combustion engines, according to the present invention, is characterized by performing the engine block and the cylinder head cooling independently of each other. For the cylinder head, the cooling is accomplished by means of forced flow of coolant. For the engine block, the cooling is accomplished by means of natural (free) convection caused by buoyancy effects. The independent cooling system for internal combustion engines, according to the present invention, permits distinct operating-regime temperatures in the cylinder head and in the engine block respectively. As a consequence, one can obtain better control of the engine heat rejection, better control of the air-fuel mixture temperature, better control of the engine pollutant emissions, faster cylinder head warming-up causing reduction in the engine cold-phase period, effective increase in the compression ratio (to much higher values than the currently attainable). The fact that the independent cooling system for internal combustion engines, according to the present invention, makes it possible an increase in the engine compression ratio to very high values (for both Otto cycle and Diesel cycle engines), characterizes the system itself by causing a substantial increase in the engine thermal efficiency, yielding, as a consequence, lower fuel consumption and lower pollutant gases emissions. The independent cooling system for internal combustion engines, according to the present invention, is also characterized by making it possible the control of the independent coolant forced flow through the cylinder head. Said control can be done by the Electronic Control Module which controls single- or multi-point fuel injection systems. The Electronic Control Module, via the coolant temperature sensor, measures the coolant temperature in a specified location and, as a function of that value and the engine operating regime (engine load and engine speed), controls the coolant pump and flow-controlling valve operation. The independent cooling system for internal combustion engines, according to the present invention, also allows the primary and secondary radiators to be located in series or in parallel, in relation to the vehicle's longitudinal axis. Description of the Drawings Figure 1 shows the functional diagram of the cylinder head independent cooling subsystem. Figure 2 shows the functional diagram of the engine block independent cooling subsystem. Figure 3 shows the functional diagram of the cylinder head independent cooling subsystem, including the electronic control module that controls the ignition and fuel-injection systems. Figures 4a and 4b are diagrams showing the coolant flow direction in an arrangement where the primary and secondary radiators are disposed in series and in parallel relatively to each other. Figure 1 shows the functional diagram of the engine cylinder head independent cooling subsystem (1), within which the coolant leaves from a expansion and filling reservoir (6), is pumped by an electromechanical or electric coolant pump (2), in order to generate the coolant forced flow to a primary radiator (4), which radiator exchanges heat with the surrounding air, and keeps the cylinder head coolant temperature on the specified level. By means of a flow-controlling valve (3), that controls the coolant flow in the independent closed circuit, the coolant gets to the cylinder head in order to cool it. A coolant temperature sensor (5) measures the temperature in a specified location of the coolant flow, making it possible a precise control of the system's operation, i. e., an accurate control of the heat transfer process. Figure 2 shows the functional diagram of the engine block (7) independent subsystem, where the coolant leaves from a expansion and filling reservoir (9) and flows naturally, by gravity, to an independent secondary radiator (8) where it exchanges heat with the surrounding ambient (air), and, after that, flows to the engine block (7) to cool it. As is known to the art, the heat flux rate to the cylinder head is higher than the heat flux rate, from the combustion gases to the engine block, so a simple natural (free) convection of the coolant in the engine block is sufficient to cool it. Figure 3, which is similar to figure 1, shows the electronic control module (10) that controls the general cooling operation. By receiving the signal from the coolant temperature sensor, the electronic control module measures the coolant temperature, and, as a function of the engine operating regime defined by the engine load and speed, controls the coolant pump (2) and the flow-controlling valve (3), a the cylinder head cooling requirements. The electronic controls module (10) also controls, as shown in figure 3, the fan (1 1) operation. The electronic control module (10) may be a sophisticated microprocessor, of any kind, of any nature, that is suitable to execute such a function. Figure 4b shows, in the independent cooling system for internal combustion engines, according to the present invention, the arrangement of the primary (4) and secondary (8) radiators in series or in parallel, relatively to the vehicle's longitudinal axis. Figure 4a shows the parallel arrangement of the primary (4) and secondary (8) radiators, also relatively to the vehicle's longitudinal axis. In the present invention, the coolant may be any kind of fluid, with any specific composition that is suitable for such a function. The preferable fluids are aqueous ones as, for instance, water mixed with additives (like glycol ethylene, etc.). The system of the present invention can provide to the cylinder head, for instance, a temperature gradient (inlet - outlet) of around 50°C, and of around 40°C for the engine block. However, an engine incorporating the claimed cooling system can operate at any coolant temperature gradient, either for the engine block or for the cylinder head. In relation to the current cooling systems described in the beginning of the preceding section, the independent cooling system, according to the present invention, has the following advantages: In the Cylinder Head: 1. Coolant flow can be generated by a low-energy-consumption electrical pump; which is directly controlled by the electronic control module. 2. The coolant volume submitted to forced flow (by the electric pump) is substantially lower, because the necessary coolant volume to cool the cylinder head is much lower than the volume required to cool the entire engine and the block alone. So, the required pumping work is lower. 3. Because of the lower coolant volume required, the control of the flow and of the coolant temperature in the cylinder head is faster and more accurate. 4. It makes possible to operate the cylinder head in the ideal working temperature which is usually different from that required by the engine block. 5. It does not require a thermostatic valve, as it needs only ai temperature sensor to automatically switch on the system. 6. It makes possible the use of a lower capacity radiator. 7. The use of independent radiators, makes possible their location in regions where the vehicle's frontal air flow is more favorable to heat transfer enhancement. 8. It makes possible better control of the engine pollutant emissions, due to the more accurate temperature control. 9. It makes possible the increase of the compression ratio and, consequently, the increase of the engine power output. 10. It makes possible better engine knocking control. 11. There is no need of any special cylinder head gasket. In the Engine Block: 1. Flow occurs by natural (free) convection and, therefore, an auxiliary pump is not needed (mechanical or electric). 2. It is not necessary the use of a thermostatic valve. The system operates in a free circuit. 3. It has an independent radiator, which has lower capacity than the ones in current systems. 4. Because the flow occurs by means of free convection, it may operate at lower pressures.

Claims: CLAIMS 1. Independent cooling system for internal combustion engines, characterized by the following: a) An independent cylinder head cooling subsystem (1), within which a coolant flows from an expansion and filling reservoir (6), is pumped by a coolant pump (2) to perform the coolant forced flow in a primary radiator (4) and in the cylinder head (1). The temperature sensor (5) measures the coolant temperature in a determined flow location, and makes it possible the control of the operation of the system. b) An independent engine block cooling subsystem (7), within which the coolant flows from an expansion and filling reservoir (9) and flows naturally to a secondary independent radiator (8) and to the engine block (7). 2. In the cylinder head cooling subsystem, according to claim 1 above, the system is characterized by having a flow-controlling valve (3) located between the primary radiator (4) and the cylinder head (1), that controls the coolant flow in the corresponding independent closed circuit. 3. According to claims 1 and 2 above, the system is characterized by having an electronic control module (10), which controls the whole cooling operation. The electronic control module, by receiving an electrical signal from the coolant temperature sensor, measures that temperature in a specified location and, depending on that value and the engine operating regime, controls the operation of the pump (2) and the flow-controlling valve (3) providing, so, the necessary cylinder head coolant flow rate. 4. According to claim 3 above, the system is characterized by the fact that the control module (10) is an electronic one. 5. According to claim 3 above, the system is characterized by having a control module (10) which controls the fan 11 operation. 6. According to claim 1, the system is characterized by having a coolant pump (2) which may be an electric or an electromechanical one. 7. According to anyone of the above preceding claims, the system is characterized by having the primary and secondary radiators (7, 8) arrangement in parallel or in series relatively to he longitudinal vehicle axis.

Inventors: GUTIERREZ HENEDINO JR, GUTIERREZ, HENEDINO, JR.
Applicants: GEN MOTORS DO BRASIL LTDA, GUTIERREZ HENEDINO JR, GENERAL MOTORS DO BRASIL LTDA., GUTIERREZ, HENEDINO, JR.
Application year: 1997
Main classification: F01P7
IPC codes: F01P3, F01P5, F01P7