LIQUID COOLING SYSTEM FOR INTERNAL COMBUSTION ENGINE

Abstract

A liquid cooling system for an internal combustion engine includes a coolant pump, an air-to-liquid heat exchanger, and a bypass loop for allowing coolant to circulate from the coolant pump to the engine without passing through the heat exchanger. A thermostatic valve mounted within a thermostat housing and including a temperature-responsive primary valve element and bypass flow control will control the flow of coolant with a spring-loaded valve disc having a conical, annular sealing surface configured for linear contact with the valve seat.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

None.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This disclosure relates to a liquid cooling system for a reciprocating internal combustion engine.

2. Related Art

Automotive internal combustion engines operate in a variety of temperature extremes. The first duty of a cooling system is to maintain the engine's operating temperature within a fairly narrow range. As exhaust emission control requirements tighten, this function has increased in importance.

In addition to controlling the ultimate temperature at which an engine operates following warm up, the cooling system desirably provides rapid warm up of the engine so as to provide heat to the passenger cabin of a vehicle as quickly as possible. To this end, coolant is circulated through a bypass, which allows the coolant to move through the engine without passing through the air-to-liquid heat exchanger, commonly termed a radiator. Once the engine attains the desired operating temperature, flow through the radiator is initiated.

The transition between bypass flow and flow through the radiator must be managed carefully so as to avoid undesirable transient flow conditions such as valve hammer, a condition characterized by a high frequency seating and unseating of the valve disc. This has presented a problem with known thermostatic temperature control devices.

It would be desirable to have a cooling system with a thermostatic valve permitting finer control of coolant temperature and flow during warm up of the engine, particularly during switchover from bypass to full flow through the radiator.

BRIEF DESCRIPTION OF THE INVENTION

According to an aspect of the invention, a liquid cooling system for an internal combustion engine includes a coolant pump, an air-to-liquid heat exchanger, and a bypass loop for allowing coolant to circulate from the coolant pump to the engine without passing through the heat exchanger. A thermostat housing is operatively connected with the coolant pump, as well as with the heat exchanger and the bypass loop. A thermostatic valve mounted within the thermostat housing includes a temperature-responsive primary valve element for controlling the flow of coolant between the coolant pump and the heat exchanger and a bypass flow control coupled to the primary valve element for controlling the flow of coolant through the bypass. The bypass flow control includes a resiliently-loaded valve disc having a conical, annular sealing surface configured for linear contact with the valve seat.

According to another aspect of the present invention, the valve disc further includes a number of continuously open bypass orifices formed in the valve disc. The valve disc is itself mounted upon a stem extending from a temperature-responsive element which operates the primary valve element.

According to another aspect of the present invention, the thermostatic valve has at least a first position in which the primary valve element is closed and the bypass flow control is open to a maximum extent and a second position in which the primary valve element is open and the bypass flow control is open to a minimum extent.

According to another aspect of the present invention, a bypass flow control includes a valve disc having a conical, annular sealing surface configured for linear contact with a valve seat incorporated within the thermostat housing. Stated another way, the bypass flow control includes a spring-loaded valve disc with a frustoconical, annular sealing surface configured for wedging contact with the thermostat housing's valve seat.

It is an advantage of a liquid cooling system according to the present invention that transitions between bypass flow, which excludes the engine's radiator, and full flow, which includes the radiator, will be managed in a manner so as to avoid unwanted temperature excursions.

It is a further advantage of a liquid cooling system according to the present invention that the thermostatic valve will exhibit superior durability characteristics as compared with prior art valves.

Other advantages, as well as features of the present invention, will become apparent to the reader of this specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a V-block engine having a cooling system according to the present invention.

FIG. 2 is a sectional view of a thermostatic valve according to an aspect of the present invention. The valve of FIG. 2 is in the closed position with respect to flow through the engine's radiator, but with the bypass flow control being in the open position.

FIG. 3 is similar to FIG. 2, but shows the primary valve element of the thermostatic valve in the open position, allowing flow through the engine's radiator, but with the bypass flow control being in a closed position, in which only liquid flowing through the bypass flows through a series of orifices.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1, engine 10 has a cylinder block, 11, upon which a pair of cylinder heads, 12, are mounted, with only one of cylinder heads 12 being shown. Engine 10 also includes a coolant pump, 14, a coolant crossover, 16, an air-to-liquid heat exchanger (“radiator”) 18, and a series of hoses. Coolant circulates generally from water pump 14 through cylinder block 11 and up through cylinder heads 12. After moving through cylinder heads 12, coolant flows into thermostat housing 26 which, as its name implies, provides a mounting place for thermostatic valve 34, including a bypass valve seat, 72 (FIGS. 2 and 3). When thermostatic valve 34 is in the open position shown in FIG. 3, coolant flows up through thermostatic valve 34 and then through coolant outlet 30 and upper radiator hose 20, and then into radiator 18. The cooled fluid then moves through lower radiator hose 24 and then through water pump 14. Leaving water pump 14, the fluid flows back through cylinder block 11, as described above.

When engine 10 is below the desired operating temperature, thermostatically responsive valve 34 will not allow coolant to flow through radiator hose 20 and into radiator 18. Rather, coolant flows through a bypass loop, 22, which is shown as including a passageway to and from water pump 14 and through cylinder heads 12 and cylinder block 11, but without including flow through radiator 18. This bypass flow allows engine 10 to warm up more rapidly. The lower temperature condition of valve 34 is shown in FIG. 2, wherein valve 34 is closed insofar as flow to radiator 18 is concerned. Thus, in FIG. 2, primary valve 46 is maintained in contact with valve cage 50 by means of primary spring 54. Note that FIG. 2 also shows resiliently-loaded bypass valve disc 58, which is slidingly mounted upon stem 52, as being in a fully open position. This allows maximum flow through bypass loop 22.

Primary valve element 38 has a temperature-responsive motor in the form of wax pellet motor 42, which has a plunger 44. When engine 10 is cold, wax pellet motor 42 is in a retracted position, allowing primary valve element 46 to shut off flow to radiator 18. Once engine 10 comes to a warmed up operating temperature, however, notice from FIG. 3 that plunger 44 now extends from wax pellet motor 42, with the result that primary valve element 46 has now been displaced from valve cage 50, thereby allowing flow through water outlet 30 and through upper radiator hose 20 to radiator 18.

Returning now to FIG. 2, it is seen that frustoconical, annular sealing surface 64 of valve disc 58 is not in contact with valve seat 72, thereby allowing bypass flow through bypass loop 22 and, therefore, rapid warm up of engine 10. Now, however, turning once again to FIG. 3, it is seen that with the action of wax pellet motor 42 and, particularly, plunger 44, bypass valve disc 58 has now been resiliently pressed into contact with valve seat 72, such that the force of spring 62 maintains frustoconical sealing surface 64 in contact with valve seat 72.

When thermostatic valve element 34 is in the position shown in FIG. 3, minimal flow is allowed through bypass orifices 68 which are formed in bypass valve disc 58. Orifices 68 are important because they would permit minimum flow through engine 10 even if thermostatic valve element 34 were to malfunction and not open correctly. Orifices 68 also help to provide a “soft” temperature transition strategy by preventing valve disc 58 from closing too quickly. Moreover, frustoconical sealing surface 64 helps to prevent valve disc 58 from closing in an unstable manner by mitigating the pressure forces acting upon valve disc 58. In turn, this enhances the durability of thermostatic valve element 34.

It is thus seen that wax pellet motor 42 functions as a thermally responsive linear actuator which positions bypass valve disc 58 against seat 72. As noted above, when thermostatic valve element 34 is in the position shown in FIG. 3, bypass valve disc 58 is maintained in contact with seat 72 by bypass spring 62, which functions as a resilient member.

Although thermostatic valve element 34 is illustrated as having a first position in which primary valve element 46 is closed and bypass flow control disc 58 is open, and a second position in which primary valve element 46 is open and bypass flow control disc 58 is open to a minimum extent while closed against seat 72, other types of thermostatic control devices may employ the present temperature-responsive primary valve element and bypass valve disc in multiple locations or operational configurations.

The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.

Claims

1. A liquid cooling system for an internal combustion engine, comprising:

a coolant pump;

an air-to-liquid heat exchanger;

a bypass loop for allowing coolant to circulate from the coolant pump to the engine without passing through the heat exchanger;

a thermostat housing operatively connected with said coolant pump, as well as with said heat exchanger and said bypass loop; and

a thermostatic valve mounted within said thermostat housing, with said thermostatic valve comprising: a temperature-responsive primary valve element for controlling a flow of coolant between said coolant pump and said heat exchanger; and a bypass flow control, coupled to said primary valve element, for controlling a flow of coolant through said bypass, with said bypass flow control comprising a resiliently biased valve disc having a conical, annular sealing surface configured for linear contact with a valve seat.

2. A liquid cooling system according to claim 1, wherein said valve disc further comprises a plurality of continuously open bypass orifices formed in said valve disc.

3. A liquid cooling system according to claim 1, wherein said valve disc is mounted upon a stem extending from a temperature-responsive element which operates said primary valve element.

4. A liquid cooling system according to claim 1, wherein said valve seat is incorporated within said thermostat housing.

5. A liquid cooling system according to claim 1, wherein said thermostatic valve has at least a first position in which said primary valve element is closed and said bypass flow control is open to a maximum extent, and a second position in which said primary valve element is open and said bypass flow control is open to a minimum extent.

6. A liquid cooling system according to claim 1, wherein said valve disc is spring loaded.

7. A thermostatic valve for use within a cooling system of a liquid cooled internal combustion engine, comprising:

a temperature-responsive primary valve element for controlling a flow of coolant between a coolant pump and a heat exchanger; and

a bypass flow control, coupled to said primary valve element, for controlling a flow of coolant through a warm up bypass, with said bypass flow control comprising a valve disc having a conical, annular sealing surface configured for linear contact with a valve seat.

8. A thermostatic valve according to claim 7, wherein said primary valve element is positioned normally closed by a resilient member and opened by a thermally responsive linear actuator.

9. A thermostatic valve according to claim 7, wherein said valve disc is configured to permit a partial flow past the disc when the disc is in contact with a valve seat.

10. A thermostatic valve for use within a cooling system of a liquid cooled internal combustion engine, comprising:

a temperature-responsive, linearly actuated primary poppet valve for controlling a flow of coolant between a coolant pump and a heat exchanger; and

a bypass flow control, resiliently coupled to said poppet valve, for controlling a flow of coolant through a warm up bypass, with said bypass flow control comprising a resiliently-loaded valve disc having a frustoconical, annular sealing surface configured for wedging linear contact with a valve seat.

11. A thermostatic valve according to claim 10, wherein said resiliently-loaded valve disc is configured for contact with a valve seat incorporated within a thermostat housing.

12. A thermostatic valve according to claim 10, wherein said resiliently-loaded valve disc is spring-loaded.