Technical Field The invention relates to a thermostat assembly used in engine cooling system, more particularly, an improvement in temperature control of the cooling system.

In art, relatively colder coolant in the radiator inlet passage is prevented to impinge upon the heat sensitive wax filled body by closing the radiator inlet via the moving valve structure at the fully closed thermostat position. Thereby the relatively colder coolant is accumulated at the radiator inlet passage. There is still a heat transfer between the relatively colder coolant and the heat sensitive wax filled body although the radiator inlet is closed. The extension of the heat sensitive wax filled body used as a valve structure to close the radiator inlet in art causes heat transmission through itself between the relatively colder coolant and the heat sensitive body. This phenomenon lets the heat sensitive body to be indirectly affected by the relatively colder coolant accumulated in the radiator inlet passage at the fully closed thermostat position. The heat sensitive body indirectly affected by the relatively colder coolant cannot sense the real temperature of the coolant recirculating the bypass circuitry and acts according to the inaccurate temperature information. This lets inaccuracy in temperature control of the engine cooling system.

The present invention provides a thermostat assembly without both direct and indirect cooling of the heat sensitive wax filled body at the fully closed thermostat position. The valve structure of the present invention is made of compounds which have low thermal conductivity such as rubber or plastic unlike the valve structure of the thermostat assemblies in the art. The rubber or plastic valve structure prevents the heat transmission between the heat sensitive wax filled body and the relatively colder coolant in the radiator inlet passage. Moreover, the sealing element on valve structure of the present invention prevents the leakage of said colder coolant from the radiator inlet passage to upon the heat sensitive body at the fully closed thermostat position by providing sealing at the radiator inlet.

Prior Art

There is not a technology that can totally transform the chemical energy in the fuel of an internal combustion engine into the mechanical energy. A big part of this chemical energy is lost as heat energy and friction energy emerged between the moving parts. The friction energy is also transformed into heat energy at last. So, the inefficiency in energy transformation from chemical to mechanical causes the accumulation of the excess heat on the engine and engine parts. In extreme cases, the excess heat causes the engine end engine parts to be damaged.

Engines in the vehicles are convenient to work under specific temperature range where the engine has its best in efficiency. Thus, the proper cooling of both engine and engine parts is very important for the vehicles. The cooling operation is provided by the engine cooling system of the vehicles.

Engine cooling system has two sub-circuits connected each other via a thermostat assembly. First coolant circulation circuit known as bypass circuit, which is through a circulation pump and engine channels while engine coolant temperature is cold enough (under a first threshold temperature). Said engine channels include the channels passing through a crankcase and the channels passing a crankcase head. When the engine coolant temperature is warm enough (above said first threshold temperature), the coolant also starts to flow through a second coolant circulation circuit. Said second coolant circulation circuit known as heat exchange circuit which is through radiator channels including radiator wings as well as said circulation pump and engine channels. The excess heat of the engine and engine parts are absorbed by a coolant flowing through the engine channels. When the recirculating engine coolant temperature is so high (above a second threshold temperature), the flow through the bypass circuit is eliminated. There is flow just through the heat exchange circuit. The coolant is cooled there via the wind and an axial fan forcing air to flow on the radiator wings. So, the excess heat is absorbed by the radiator channels including radiator wings. Consequently, the excess heat is released to environment by removing it away from the engine and engine parts. Said thermostat assembly controls the coolant to flow through these sub-circuits within different rates according to the temperature of the coolant in engine channels to maintain the best engine working temperature. So, the embodiments of the thermostat assemblies should be convenient to control the mentioned flow rate. They are generally at least three-way to sustain the variable connection. First way is coming from the engine channels, second way is coming from radiator channels and lastly third way is going to engine channels.

A thermo-actuator within said thermostat assembly comprises a heat sensitive wax filled body, a valve structure mounted on said body and a moving piston. Said heat sensitive wax filled body is a hydraulic system structured by riveting a heat conductive reservoir and a resilient rubber diaphragm. There is a hydraulic fluid known as wax compound inside the hydraulic system. Said piston is inserted into the recess of the diaphragm outwardly. The temperature difference between said hydraulic fluid and the recirculating engine coolant causes the heat transmission thereof through the heat conductive reservoir surface in contact with both the coolant and the hydraulic fluid. The heat transmission continues until the temperature of hydraulic liquid is equal to the temperature of the recirculated engine coolant. Thereby the temperature of the recirculated engine coolant is sensed by said heat sensitive wax filled body. This means that an increase in the temperature of the recirculated engine coolant causes an increase in the temperature of the hydraulic fluid and likewise, a decrease in the temperature of the recirculated engine coolant causes a decrease in the temperature of the hydraulic fluid.

The thermo-actuator is in closed position while engine coolant temperature is convenient to let the engine work efficiently. At this closed position, the thermo-actuator has its minimum length. During the closed position of the thermo-actuator, the valve structure mounted on the heat sensitive wax filled body closes the radiator inlet of said thermostat assembly. The closure of the radiator inlet prevents the relatively colder coolant flowing through the radiator channels to flow through the engine channels. So, the recirculating engine coolant continues to flow just through the first coolant circulation circuit. The thermostat assembly position allowing engine coolant to flow just through bypass circuit is known as fully closed thermostat position.

When the engine coolant temperature is warm enough (upon first threshold values), the wax inside the heat sensitive wax filled body starts to expand. The increase in the volume of the hydraulic fluid causes the resilient diaphragm structure to tighten up. This resulted in the forward motion of the piston. However, due to a structure restricting forward motion of the piston end, the heat sensitive wax filled body and engaged valve structure moves back instead of forward motion of piston end. When the engine coolant temperature reaches the highest temperature values (second threshold values) defined for the thermostat assembly, the thermo-actuator within the thermostat assembly reaches its maximum length too. Thereby the valve structure closes the bypass inlet. The closure of the bypass inlet allows the all amount of the coolant to flow just through the second coolant circulation circuit known as the heat exchange circuit including the radiator channels and the engine channels. So, the engine coolant continues to circulate through second coolant circulation circuit until the coolant temperature decreases again under second threshold engine temperature. The thermostat assembly position allowing engine coolant to flow just through the heat exchange circuit is known as fully opened thermostat position.

The thermostat assembly allows the engine coolant to flow through both coolant circulation circuits during the length of the thermo-actuator is between its maximum and its minimum. The thermostat assembly position allowing engine coolant to flow through both bypass circuit and heat exchange circuit is known as partially opened thermostat position.

When the temperature of the coolant flowing through both the first circulation circuit and the second circulation circuit decreases under the first threshold temperature values, the temperature of hydraulic fluid within the heat sensitive wax filled body decreases too due to the heat transmission between the coolant and hydraulic fluid. The decrease in the temperature of the hydraulic fluid causes the decrease in the pressure of the hydraulic fluid. Thereby the shrinkage in the hydraulic fluid due to the pressure drop lets the volume of the hydraulic fluid to decrease. The decrease in the hydraulic fluid volume causes the diaphragm structure to move back, so the piston inserted into the recess of diaphragm to move back too. Consequently, the thermo-actuator has again its minimum length value which provides to close the radiator inlet of the thermostat assembly.

The heat sensitive wax filled body at the fully closed position of the thermostat assemblies in the art is indirectly affected the relatively colder coolant in the radiator inlet passage although the radiator inlet is closed by the valve structure. The conductive valve structure of these thermostat assemblies, which obtained by extending the heat sensitive body, causes an indirect heat transfer through therefor between the relatively colder coolant and the hydraulic fluid within the heat sensitive body even the radiator inlet is closed. There should not any heat transfer between the relatively colder coolant within the radiator inlet passage and the hydraulic fluid within the heat sensitive body at the fully closed position of the thermostat assembly for that the heat sensitive wax filled body to sense the temperature of the recirculated engine coolant with more accuracy.

The document US5727729 aims to prevent relatively colder coolant entering the thermostat assembly from bottom hose of the radiator (radiator inlet) to impinge directly upon the heat sensitive wax filled body at the partially or fully opened thermostat position. There are two valve members connected to a temperature responsive valve actuating means. A first valve member is to regulate a flow of cooled coolant from radiator inlet to outlet while second valve member is to regulate the flow from bypass inlet to outlet. The said first valve member extents outwardly from said valve actuating means and is arranged so as to deflect any relatively colder coolant entering toward said thermostat assembly through said radiator inlet passage away from said heat sensitive wax filled body of said valve actuating means. But the thermostat assembly is indirectly affected by the relatively colder coolant in radiator inlet passage due to the first valve member even the radiator inlet is fully closed. The communication (heat transmission) between the hydraulic fluid within heat sensitive wax filled body and the relatively colder coolant within the radiator inlet passage continues even at the fully closed thermostat position due to the conductive nature of the first valve element extending from the heat sensitive wax filled body. Heat conduction through the first valve extension causes the hydraulic fluid within the heat sensitive wax filled body to be indirectly affected the relatively colder coolant within the bottom radiator hose. This indirectly cooling of the heat sensitive wax filled body and the hydraulic fluid within the body due to the relatively colder coolant within the bottom radiator hose at the fully closed thermostat position prevents the thermostat assembly to sense the real temperature of the engine coolant flowing through the engine channels.

As a result, there is any document focused on preventing the indirectly cooling of the heat sensitive wax filled body due to the relatively colder coolant in the radiator inlet passage at the fully closed thermostat position. So, the solution of the present invention is required.

Objectives and Short Description of the Invention

Aim of the present invention is to present a thermostat assembly which prevents the heat sensitive wax filled body of a thermo-actuator to be directly or indirectly affected by the relatively colder coolant in the radiator inlet passage at the fully closed thermostat position. The thermostat assemblies in the art have a valve structure formed with valve elements extending from the heat sensitive wax filled body. So, the heat transfer between the heat sensitive body and said relatively colder coolant in the radiator inlet passage continues through the heat conductive valve element of the valve structure even at fully closed thermostat position.

A rubber or plastic valve structure mounted on the heat sensitive wax filled body does not allow any indirect heat transfer between said relatively colder coolant in the radiator inlet passage and the heat sensitive body at the fully closed thermostat position while a sealing element located on the valve structure does not allow any direct heat transfer thereof. Thereby the invention ensures the heat sensitive body to sense just the temperature of the recirculated engine coolant at the fully closed thermostat position. This provides an engine cooling system to operate more accurately unlike the engine cooling system comprising the thermostat assemblies in the art.

Description of the Figures

In the figure 1a, a perspective view of a sealing element and a valve structure of the present thermostat assembly are given. A groove convenient to the sealing element is structured through top of said valve structure. In the figure 1 b, a perspective view of the present valve structure with said sealing element located to said groove is given.

In the figure 2a and 2b, perspective views of the present valve structure mounted on a thermo- actuator are given.

In the figure 2c, a cross-sectional view of the present valve structure mounted on a thermo-actuator is given. In the figure 3, a cross-sectional view of the present thermostat assembly at the fully closed thermostat position is given.

In the figure 4, an exploded perspective view of the present thermostat assembly is given.

In the figure 5, a cross sectional view of the conventional thermostat assembly is given. The valve structure formed by extending the heat sensitive wax filled body is shown. Since the valve is structured as an extension of the wax filled body of thermo-actuator within conventional thermostat assemblies, even at the fully closed thermostat position, the heat transfer between the heat sensitive wax filled body and the relatively colder coolant in the radiator inlet passage continues indirectly through the conductive valve structure. Reference Numerals

10. Valve structure

11. Groove

20. Sealing element

30. Thermostat assembly

31. Bypass inlet

32. Radiator inlet

33. Outlet

34. Body

35. Cover

36. Valve seat

37. Spring

38. Thermo-actuator

38.1. Piston

38.2. Heat sensitive wax filled body Detailed Description of the Invention

This invention relates to a thermostat assembly (30) with a non-conductive valve structure (10) and a sealing element (20) on the top of said valve structure (10) to prevent direct and indirect cooling of heat sensitive wax filled body (38.2) at the fully closed thermostat position.

The purpose of the closing the radiator inlet (32) is to prevent the relatively colder coolant to flow from radiator channels to engine channels when the recirculated engine coolant temperature is convenient for engine to work efficiently. Although the closure of the radiator inlet (32) prevents the relatively cold coolant to directly impinge on the heat sensitive wax filled body (38.2) and to flow through the heat exchange circuit at the fully closed thermostat position, the valve structure (10) formed by extending of the heat sensitive wax filled body (38.2) in the art causes the heat sensitive wax filled body (38.2) to be indirectly affected from the relatively colder coolant in the radiator inlet (32) passage. So, the heat sensitive wax filled body (38.2) could not sense the real engine coolant temperature. In extreme cases, this lets boiling of the coolant in the engine channels.

The present invention provides a thermostat assembly (30) with an improved valve control by preventing both direct and indirect cooling of the heat sensitive wax filled body (38.2) at the fully closed thermostatic valve position. Said valve structure (10) of the present invention prevents both direct and indirect heat transfer between the heat sensitive wax filled body (38.2) and the relatively colder coolant in the radiator inlet (32) passage at the closed thermostat position. A ring-shaped sealing element (20) settled on the ring-shaped groove (11) on the valve structure (10) seals the radiator inlet (32) at the fully closed thermostat position by merging the valve seat (36) structured on the inside surface of the cover (35). So, there is any relatively colder coolant leakage from the radiator inlet (32) passage to both on heat sensitive wax filled body (38.2) and engine channels. Also, the indirect cooling of the heat sensitive wax filled body (38.2) occurred due to the heat transmission between the relatively colder coolant in the radiator inlet (32) passage and the heat sensitive wax filled body (38.2) through the conductive valve structure (10) of the art is prevented by the present valve structure (10) made of non-conductive material. Besides the said sealing element (20) is made of non-conductive material too. Consequently, the present thermostat assembly (30) comprising said valve structure (10) and said sealing element (20) on the valve structure (10) provides an engine cooling system having better temperature control, acting just according to the recirculated engine coolant temperature. Explanation of the given figures from 1 to 5 can provide a better understanding of the present invention. A perspective view of said sealing element (20) and said valve structure (10) comprising said groove (11) structure is given in figure 1a. Figure 1 b shows a perspective view of combined embodiment of said sealing element (20) and said valve structure (10).

Different perspective views of said valve structure (10) mounted on a thermo-actuator (38) are given in figure 2a and figure 2b. In figure 2c, a cross-sectional view of said valve structure (10) mounted on a thermo-actuator (38) is given.

In figure 3, there is a cross-sectional view of present thermostat assembly (30) at the fully closed thermostat position. Although said thermostat assembly (30) in figure 3 has three ways: bypass inlet (31), radiator inlet (32) and outlet (33), the present valve structure (10) could be used also in the other embodiments of all thermostat assemblies (30).

The present valve structure (10) prevents cold coolant flow from the radiator inlet (32) passage to upon the heat sensitive wax filled body (38.2) by locating on said valve seat (36) at the fully closed thermostat position. Besides coolant leakage occurred through gaps between said valve structure (10) and the valve seat (36) at the fully closed thermostat position in art is prevented by said sealing element (20) mounted to a groove (11) on said valve structure. The sealing element (20) is more flexible than the both valve structure (10) and cover (35) material. Thereby the sealing element (20) provides a high quality of seal between the valve structure (20) and valve seat (36) by spreading to all gaps thereof at the fully closed thermostat position. Also, unlike the conductive valve structure (10) of the thermostat assemblies (30) in the art, the present valve structure (10) and said sealing element (20) are products of non-conductive materials. An exploded perspective view of the present thermostat assembly (30) is shown in figure 4. Here, the present valve structure (10) comprising a groove (11) structure and the sealing element (20) which will be located on the groove are shown in assembling phase.

A cross-sectional view of a conventional thermostat assembly (30) comprising a conductive valve structure (10) formed by the extensions of the heat sensitive wax filled body (38.2) is shown in figure 5. Actually, the main purpose of all valve structures (10) is to prevent heat transfer through the radiator inlet (32) by closing the radiator inlet (32) at the fully closed thermostat position. Although the conventional valve structure (10) extending from the heat sensitive wax filled body (38.2) also prevents direct heat transfer through the radiator inlet (32) at the fully closed thermostat position, there is still an indirect heat transfer through the radiator inlet (32) via the conductive valve structure (10). The conductive valve structure (10) formed by the extension of heat sensitive wax filled body (38.2) in art causes the heat transfer between the heat sensitive wax filled body (38.2) and the relatively colder coolant in the radiator inlet (32) passage.