Cooling system for an internal combustion engine, particularly for motor vehicles

Abstract: The system includes a hydraulic circuit (1) for supplying a flow of coolant to the engine (E), comprising a circulation pump (2), a radiator (4) connected to the engine (E), a by-pass duct (6) parallel to the radiator (4), and a regulating valve (10) capable of adjusting the ratio of the flows of liquid supplied to the engine (E) through the by-pass duct (6) and the radiator (4) respectively. The output of the circulation pump (2) varies as a function of a control signal. A sensor (11) provides signals indicating the temperature of the liquid flowing through a predetermined zone of the engine (E) or the hydraulic circuit (1). An electronic unit (12) connected to the sensor (11) controls the pump (2) such that the output of this latter varies depending on the temperature detected by the sensor (11). The regulating valve (10) modifies the ratio of the aforesaid flows of liquid as the output of the pump (2) varies.

Description: The present invention concerns cooling systems for internal combustion engines, particularly for motor vehicles. More specifically, the invention relates to a cooling system of the kind defined in the preamble of Claim 1. A cooling system of this kind is disclosed in EP-A-0 557 113. In that prior cooling system the regulating valve is an electrically controlled valve which is directly driven by an electronic control unit which also drives the circulation pump. The object of the present invention is to produce an improved cooling system for an internal combustion engine. This and other objects are achieved according to the invention with a cooling system as defined in claim 1. Further characteristics and advantages of the invention will become clear from the following detailed description, given purely by way of non-limitative example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of an embodiment of a cooling system for an internal combustion engine according to the invention; and Figure 2 is a view in section of a regulating valve included in the cooling system of Figure 1. In Figure, 1, the letter E indicates an internal combustion engine for a motor vehicle. A cooling system generally indicated 1 is associated with the engine E. This system comprises a hydraulic circuit for supplying a flow of coolant to the engine E. The coolant may, for example, be a mixture of water and anti-freeze and anti-corrosion agents. In the schematically illustrated embodiment the hydraulic circuit of the cooling system includes an electric circulation pump 2, the outlet or delivery of which is connected to the coolant inlet 3 to the engine E. The pump 2 is, for example, an electric pump, preferably of the rotary kind, the output of which varies with the speed of rotation of its rotor. A radiator (a liquid/air heat exchanger) 4 has its inlet connected to the coolant outlet 5 from the engine E. The radiator outlet 4 is connected to an inlet 10b of a regulating valve generally indicated 10. In Figure 1, the reference numeral 6 indicates a by-pass duct connected substantially parallel to the radiator 4, between the outlet 5 of the engine E and a further inlet 10a of the regulating valve 10. The by-pass duct 6 may, if appropriate, extend through a heat exchanger (not shown), for example, for heating the air entering the passenger compartment. The outlet 10c of the regulating valve 10 is connected to the inlet of the circulation pump 2. An electrical temperature sensor is indicated 11 in Figure 1. In the embodiment illustrated by way of example in this figure, the sensor 11 is located close to the coolant inlet 3 of the engine E. The temperature sensor 11 could however be located elsewhere, for example, close to the outlet 5 of the engine E, or within the engine E, or even at a predetermined point in the hydraulic circuit affected by the coolant flow. The reference numeral 12 indicates an electronic control unit to which the outlet of the temperature sensor 11 is connected. The control unit 12 is connected to the electric motor which operates the electric pump 2, and controls the said pump in such a way that the output of this latter varies in a predetermined manner depending on the temperature detected by the sensor 11. As will become clearer from the description of the embodiment shown in Figure 2, the regulating valve 10 is generally capable of adjusting the ratio between the flows of coolant supplied to the engine E through the by-pass duct 6 and the radiator 4, respectively. The regulating valve 10 of Figure 2 includes a hollow body formed, by way of example, in two parts 13 and 14 sealingly coupled to each other. An inlet connection 10a and an outlet connection 10c are formed in the body 10. An inlet connection 10b is formed in the part 14 of the valve body. A guide element generally indicated 15 is fixed between the two parts 13 and 14 of the valve body. In the embodiment illustrated by way of example, the guide element 15 includes a disc portion 15a having a plurality of peripheral apertures 15b and a central protrusion or boss 15c in which an axial passage 15d is formed. The part 14 of the valve body 10 has a restriction 16 close to the inlet connection 10b. This restriction acts as a valve seat with which a valve shutter 17 fixed to a shaft 18 slidingly mounted in the passage 15d of the guide element 15 cooperates. A coil spring 19 is interposed between the disc 15a of the guide element 15 and the shutter 17, and holds this latter in the position illustrated in Figure 2, that is, against the seat of the valve 16. The cooling system described above functions as follows. A flow of warm liquid from the engine E reaches the inlet 10a of the valve 10, while relatively cooler liquid from the radiator 4 reaches the inlet 10b of such valve. The valve 10 is usually closed, that is, the shutter 17 usually (when the engine is cold) closes the inlet 10b of the valve. When the temperature detected by the sensor 11 exceeds a predetermined value, the control unit 12 causes the electric pump 2 to rotate so that the difference between the pressures on the lower and upper surfaces of the shutter 17 exceeds the resistance of the spring 19, and the shutter 17 moves away from the seat 16, opening the way to the relatively cooler fluid coming from the radiator 4. The valve 10 then enables the warm liquid from the by-pass duct to mix with the relatively cooler liquid from the radiator 4. The control unit 12 controls the speed of rotation of the pump 2 in such a way as to control the temperature of the fluid supplied to the engine E as desired. The system according to the invention has various advantages. In the first place, it is simpler and less costly than the conventional arrangements which use a pump rotated by the internal combustion engine, and a thermostatic regulating valve. From the constructional point of view, the regulating valve 10 may be integrated, that is, formed as a unit with the electric pump itself, with consequent advantages also from the point of view of the assembly and installation of the cooling system, in particular its hydraulic circuit. Naturally, as is evident to the expert in the field, numerous variants may be introduced into the system described above with reference to the drawings. In particular, the regulating valve can be formed differently to that illustrated with reference to Figure 2. Furthermore, the pump and associated regulating valve can be located on the side where the liquid leaves the engine E, rather than on the inlet side. Naturally, the principle of the invention remaining the same, the embodiments and details of manufacture may be widely varied with respect to that described and illustrated by way of non-limitative example, without by this departing from the ambit of the present invention as defined in the attached Claims.

Claims: A cooling system for an internal combustion engine (E), including a hydraulic circuit (1) for supplying a flow of coolant to the engine (E), including a circulation pump (2), the output of which is variable as a function of a control signal, a radiator (4) connected to the engine (E), in a radiator line, a by-pass duct (6) essentially parallel to the radiator (4), and a regulating valve (15-19) coupled to the radiator line and permanently communicating with the by-pass duct (6) and the engine (E), and capable of adjusting the ratio of the flows of coolant supplied to the engine (E) through the by-pass duct (6) and the radiator (4), respectively, by controlling the opening of the radiator line; a sensor (11) capable of providing signals indicating the temperature of the liquid flowing through a predetermined zone of the engine (E) or the said hydraulic circuit (1); an electronic unit (12) connected to the sensor (11) to control the said pump (2) in such a way as to vary the output of this latter in a predetermined manner depending on the temperature detected by the sensor (11); the system being characterised in that said regulating valve (15-19) is a valve responsive to the pressure difference thereacross, and said electronic unit (12) is adapted to control the output of said pump (2) so as to cause a variation of the pressure difference across said regulating valve (15-19) and a corresponding adjustment of said flow ratio. A cooling system according to Claim 1, characterised in that the said pump (2) is a rotary electric pump. A cooling system according to Claim 1 or Claim 2, characterised in that the regulating valve (10) comprises a hollow body (13, 14) having first and second inlets (10a, 10b) connected respectively to the by-pass duct (6) and the outlet of the radiator (4), and an outlet (10c) connected to the coolant inlet (3) to the engine (E); the first inlet (10a) of the valve (10) being permanently in communication with the outlet (10c); a valve seat (16) being provided between the second inlet (10b) and the outlet (10c), with which seat is associated a valve shutter (17) movable in the body (13, 14); the said shutter (17) being able to move away from the seat (16) against the action of biasing means (19) when the pressure difference between the region of the body upstream of the seat (16) and the region downstream of the said seat (16) exceeds a predetermined value.

Inventors: BARTOLAZZI ANDREA, BARTOLAZZI, ANDREA
Applicants: GATE SPA, GATE S.P.A.
Application year: 1998
Main classification: F01P7
IPC codes: F01P5, F01P7