WO2019066758A1

WO2019066758A1 - A thermostat assembly with an improved bypass control

Info

Publication number: WO2019066758A1
Application number: PCT/TR2018/050504
Authority: WO
Inventors: Hikmet KANBUR
Original assignee: Kirpart Otomotiv Parcalari Sanayi Ve Ticaret Anonim Sirketi
Priority date: 2017-09-26
Filing date: 2018-09-18
Publication date: 2019-04-04
Also published as: CN111183278B; IL273565A; TR201714299A1; CN111183278A; EP3688292A1

Abstract

This invention relates to a thermostat assembly (32) ensuring a pilot flow (P) at the fully open thermostat position from the bypass inlet (32.1) to outlet (32.3) through the conduits (20) designed on the valve (10) structure to prevent the accumulation of the warm coolant around the heat sensitive wax filled body (38.2) of the thermo-actuator (38). The warm coolant accumulation causes the heat sensitive wax filled body (38.2) to not sense the main flow (M) temperature during the fully open thermostat position. An improved bypass control is aimed with the enlarged heat transmission area by reducing contact area (38.3) as well as the designed conduits (20) on the valve (10) structure of the present invention.

Description

A THERMOSTAT ASSEMBLY WITH AN IMPROVED BYPASS CONTROL

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.

The coolant flow through bypass circuit is completely prevented by closing bypass inlet at the fully opened position of the three-way thermostat in the art. The interruption in coolant flow causes warm coolant accumulation around the heat sensitive wax filled body located in bypass inlet or outlet of thermostat assembly. The warm coolant accumulation around the heat sensitive wax filled body in the art of three-way thermostat assembly prevents the heat sensitive body to sense the real engine coolant temperature.

The present invention provides a thermostat assembly with an improved bypass control even at the fully opened thermostatic valve position. The valve structure of the present invention provides a pilot flow from bypass inlet to outlet through the conduits designed to prevent the warm coolant accumulation at the fully opened thermostatic valve position.

Prior Art

More than half of the energy used in motors is wasted as heat energy. So, all vehicles need an engine cooling system to be protected from the wasted heat energy accumulated on the engine systems. There are two kind of engine cooling system: air based and water based. It has become increasingly popular in recent years to use the water based engine cooling system.

The engine cooling system ensures the absorption of the excess heat of the engine by the coolant, and also the transmission of the excess heat by radiator channels to environment. The maintaining of the cooling system has importance to supply the optimum working conditions for the engine and the engine components to survive without damage. The three-way thermostats used in the engine cooling system are well known in the art. The engine cooling system has two different coolant flow circuits according to the coolant temperature value sensed by the thermostat assembly of the system. The first one is bypass flow circuit as the primary flow circuit between engine channels and thermostat assembly, and the second one is the heat exchange flow circuit as the secondary flow circuit between engine channels, thermostat assembly and the radiator channels. Also, the cooling system employs a circulating pump to force to engine coolant to circulate through the system and an axial fan to force air against the radiator channels. The mentioned engine coolant is the mixture of water and antifreeze in specific ratios.

The temperature sensed by the heat sensitive wax filled body of thermo-actuator within the thermostat assembly defines which circuit will be used. Thereby the thermostat assembly between these circuits connects them to each other continuously to ensure the control of the engine coolant temperature to prevent engine damage caused from the overheating of engine.

Three-way thermostat assemblies generally comprise two inlets and one outlet. The first inlet comes from engine via bypass circuit, the second inlet comes from the radiator via heat exchange circuit, and the outlet goes to engine channels. Another thermostat assembly embodiment has different connections such as two outlets and one inlet. The first outlet goes to bypass circuit, the second outlet goes to heat exchange circuit and the inlet comes from the engine channels. Although these thermostat assemblies have different connections, they work with same principles.

All the water based engine cooling systems work with the same manner. The temperature of the cold engine coolant sensed by the heat sensitive wax filled body of the thermo-actuator within the thermostat assembly causes to thermostatic valve to maintain to be in fully closed position. The fully closed position allows the liquid pumped by the circulation pump to flow primarily through the bypass circuit. When the cold engine coolant circulates through the bypass circuit, it absorbs all the excess heat of engine by passing through the bypass channel and the water jackets.

The water jacket surrounding cylinders in the cylinder block is the enclosure directing the flow of the engine coolant around the engine parts. Thus, the cooling of the engine parts is provided by the enclosure. Besides, there are narrow passages within the water jacket for a proper cooling throughout the engine.

When the coolant temperature reaches a first threshold temperature of the thermostatic valve, the wax in the heat sensitive wax filled body of the thermo-actuator within thermostat assembly starts to expand and to push the rubber diaphragm structure forward. The rubber diaphragm is located on the heat sensitive wax filled body by crimping operation. A piston is inserted into the recess on the diaphragm and guided through the recess. So, the forward motion of the diaphragm causes forward motion of the piston. A spring settled under the thermostatic valve produces a spring force which continuously pushes the thermo-actuator assembly from the bypass inlet to the radiator inlet. The purpose of the spring is to provide the maintaining of the bypass flow by closing the radiator inlet with the valve structure. Thereby the coolant flow through radiator inlet to heat exchange circuit is prevented until the engine coolant and consequently wax is warm enough to push back the spring by pushing the recess of the rubber diaphragm forward. As a result, the piston pushed forward in the limited motion interval of the thermostat interior causes the valve structure of the thermo-actuator to pushes back itself. Eventually this lets the bypass inlet to close.

During the position change of the thermostat from the fully closed position to fully opened position, there is also another thermostat position between these two positions: partially opened thermostat position.

The coolant at the first threshold temperature or over the first threshold temperature causes the thermostat to change position from the fully closed position to partially open position. The engine coolant over first threshold temperature starts to circulate both through the bypass circuit and heat exchange circuit while the engine coolant under first threshold temperature circulates just through the bypass circuit. At the partially open thermostat position, the coolant passes from both bypass inlet and radiator inlet to outlet (engine channels).

When the engine coolant temperature reaches a second threshold temperature, the thermostat comes to the fully open position from the partially open position. At the fully open thermostat position, the coolant flow is absolutely restricted through the bypass inlet to engine outlet. The engine coolant continues to circulates just through the heat exchange circuit including the radiator channels and wings. The warm coolant passes through the radiator channels and wings at both partially and fully open thermostat position. So, the warm coolant is cooled via the wind sourced by the speed of the vehicle against on the radiator wings settled in front of vehicles and also an axial fan to force air against the radiator channels. Eventually, the cooled engine coolant causes the thermostat to change position from the fully open position to partially open position and then lastly to fully closed position when the engine coolant is cold enough (under the first threshold temperature). From the beginning, the engine coolant starts to circulate just through the bypass circuit until the liquid reaches the first threshold temperature values of thermostat assembly again. The engine cooling system in the art is a functioned system. The coolant flowing through the bypass inlet to outlet during both fully closed and partially opened position of the thermostat is restricted at the fully opened position of the thermostat. This situation results in the accumulation of the warm coolant around the heat sensitive wax filled body of the thermo-actuator in the bypass inlet at the fully open thermostat position. Thereby the thermostat continues to be in the fully opened position. The engine coolant also continues to circulate through the heat exchange circuit although the coolant is cold enough. Briefly, the accumulated warm coolant around the heat sensitive wax filled body of the thermo-actuator in the bypass inlet prevents the heat sensitive wax filled body to sense the real engine coolant temperature. Thus, the improper functioning of the thermostat assembly lets the reducing of the vehicle performance. In extreme cases, it lets the engine and other engine parts to be damaged.

The thermostats direct the coolant flow between through the engine channels and the radiator channels according to the temperature values of the engine coolant. So, the performance of thermostat assembly has a big importance for a well functioned engine cooling system. The performance of the thermostat assembly depends directly on the fast and accurate sense of the real engine coolant temperature by the heat sensitive wax filled body.

In the internal hydraulic system of the thermo-actuator, the hydraulic liquid (wax) is closed inside between the heat sensitive body and rubber diaphragm by crimping each other. The wax causes the forward motion of the diaphragm and consequently motion of the piston to compensate the high hydraulic fluid volume at increasing temperatures. Thus, the wax must accurately sense the real engine coolant temperature and directs the coolant flow accordingly. But the accumulated warmer coolant around the heat sensitive part of the thermo-actuator at the fully opened thermostat position prevents the heat sensitive wax filled body of thermo-actuator to sense the real engine coolant temperature. Thereby it prevents the heat sensitive wax filled body to direct the coolant flow according to the real information. For a fast and accurate temperature control in the engine cooling system, the heat sensitive wax filled body should be made from most heat-permeable material. Also, the removing of the local heat residues accumulated around the heat transmission area of the heat sensitive wax filled body and supplying wider heat transmission area are necessary. The document US5727729 aims to prevent relatively cold coolant entering the thermostat assembly from bottom hose of the radiator (radiator inlet) to impinge upon the heat sensitive wax filled body. There are two valve members connected to a temperature responsive valve actuating means (valve structure). 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 of bypass coolant 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 fluid entering toward said thermostat assembly through said radiator inlet passage away from said heat sensitive wax filled body of said temperature responsive valve actuating means. The present invention and said invention both are focused on the effective coolant temperature control to ensure that they sense the temperature of the recirculated bypass flow (real engine coolant) but said invention has two disadvantages: firstly it is more expensive to produce than conventional thermostat assemblies and secondly 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 heat sensitive wax filled body and the coolant in the radiator inlet at the fully closed thermostat position due to the first valve extension there of causes the heat sensitive wax filled body to be affected the relatively colder coolant in the radiator hose. This indirectly cooling of the heat sensitive wax filled body prevents the heat sensitive body to sense the real temperature of the engine coolant flowing through the engine channels. As a result, there is any document focused on the removing of the local temperature residues accumulated around the heat sensitive wax filled body at the fully opened thermostat position. So, the solution of the present invention is required.

Objectives and Short Description of the Invention

The invention relates to a thermostat assembly ensuring a pilot flow at the fully open thermostat position from the bypass inlet to outlet through the conduits. The conduits are designed both on valve surface and the curved valve surface of the thermo-actuator. Accumulated warm coolant around the heat sensitive wax filled body causes the body to not sense the main flow temperature during the fully opened thermostat position. The conduits and the curved valve surface prevent the accumulation of the warm coolant around the heat sensitive wax filled body of the thermo-actuator. Description of the Figures

In the figure 1 a, a perspective view of a present valve structure of the thermo-actuator within the present thermostat assembly is given. The X shows the designed part of the invention. It includes both conduits on the valve surface and conduits on the curved valve surface. Also, the X includes the curved valve surface which provides easy coolant flow by reducing friction. Different perspective views of a thermo-actuator assembly with said valve structure are given in figures 1 b and 1 c. The invention provides enlarged heat transmission area by reducing the contact area between the heat sensitive wax filled body and the valve structure. The enlarged heat transmission area is supplied by a ring-shape cavity grooved at the contact surface between the heat sensitive wax filled body and valve structure. Said ring-shaped cavity is shown in figure 1 c. Also, a cross sectional view of said thermo-actuator assembly with the valve structure is given in figure 1 d. Said conduit structure allowing pilot flow through bypass circuit at the fully opened thermostat position and said cavity structure providing enlarged heat transmission area are shown in the cross-sectional view of the thermo-actuator assembly with the valve structure.

Cross sectional views of thermo-actuator assembly from two different perspectives are given in figure 2a and 2b. A cross sectional view and a perspective view of the thermostat assembly are given in figure 2c and in figure 2d respectively. Figure 3a and 3b shows cross-sectional views of the fully closed thermostat assembly from different perspectives, allowing the coolant flow just from the bypass inlet to outlet. The coolant flowing through the primary circuit known as "bypass circuit" absorbs the excess engine heat to maintain optimum engine working conditions. Figure 3c shows a top view of the fully closed thermostat assembly. Figure 4a an 4b depicts cross-sectional views of the partially opened thermostat assembly from two different perspectives, allowing both coolant flow from radiator inlet to outlet and from bypass inlet to outlet. The coolant flowing through the heat exchange circuit is known as secondary circuit as well as through the bypass circuit known as primary circuit. Figure 4c shows a top view of the partially opened thermostat assembly. Figure 5a and 5b shows cross-sectional views of the fully opened thermostat assembly from two different perspectives, allowing the coolant flow just from radiator inlet to outlet. The coolant flowing through the secondary circuit known as "heat exchange circuit" cools the warm coolant coming from engine channels via an axial fan. The fan forces air against the radiator channels.

Figure 5c gives a close view of a conduit allowing a pilot flow from bypass inlet to outlet through the bypass circuit at the fully opened thermostat position.

Figure 5d shows a top view of the fully opened thermostat assembly.

The diagrams in the figure 6, 7 and 8 are for the three-way thermostat embodiment structured as two inlets, one outlet.

In the figure 6, the diagram depicts the coolant flow circuit at the fully closed thermostat position allowing the coolant to flow just from bypass inlet to outlet through the bypass circuit.

In the figure 7, the diagram depicts the coolant flow circuit at the partially open thermostat position allowing the coolant to flow both through the bypass circuit and the heat exchange circuit.

In the figure 8, the diagram depicts the coolant flow circuit at the fully opened thermostat position allowing a pilot flow from the bypass inlet to outlet. At the fully opened thermostat position, a pilot coolant flow is provided by the conduits from the bypass inlet to outlet as well as the main flow from the radiator inlet to outlet. The pilot flow is provided through the designed conduits on the valve structure of the thermo-actuator. Thermostat assemblies in the art allow a coolant flow just from the radiator inlet to outlet at the fully opened position of the thermostat.

Figure 9 shows an exploded perspective view showing parts of the thermostat assembly of the present invention including the designed valve structure of thermo-actuator. The valve structure includes the conduits permitting a pilot flow between bypass inlet to outlet at the fully opened position of the thermostat.

Reference Numerals

10. Valve

11. Valve surface

12. Curved Valve surface

13. Valve arm

20. Conduit

30. Sealing element

32. Thermostat assembly

32.1. Bypass inlet

32.2. Radiator inlet

32.3. Outlet

34. Body

34.1. Body nest

34.2. Body seat

35. Cover

35.1. Cover seat

35.2. Piston seat

37. Spring

38. Thermo-actuator

38.1. Piston

38.2. Heat sensitive wax filled body

38.3. Contact area

38.4. Heat transmission area

38.5. Cavity

CP. Circulation pump

E. Engine block

R. Radiator

M. Main Flow

P. Pilot Flow

X. Designed part

Detailed Description of the Invention

This invention relates to a three-way thermostat assembly (32) with an enlarged heat transmission area (38.4) on a heat sensitive wax filled body (38.2) and at least one conduit (20) structure on the valve surface (1 1) of the thermo-actuator (38).

Warm coolant accumulation around the heat sensitive wax filled body (38.2) at the fully opened position of three-way thermostat assemblies (32) in the art causes the heat sensitive wax filled body (38.2) to not sense the real engine coolant temperature. The warm coolant accumulation is prevented via said conduits (20) designed on the valve (10) structure of the present invention. There is a contact area (38.3) between some part of the outer surface of heat sensitive wax filled body (38.2) and the inner surface of the valve (10) structure which mounted on the mentioned part of the heat sensitive body. Besides there is a heat transmission area (38.4) where the other part of the outer surface of heat sensitive wax filled body (38.2) contacts with the coolant. The size of said heat transmission area (38.4) defines the heat transmission rate between the coolant and the hydraulic liquid (wax). The increasement in the heat transmission area (38.4) provides the increasement in the heat transmission rate while the decreasement in the heat transmission area (38.4) causes the decreasement in the heat transmission rate. The increasement in the heat transmission rate provides quick reaction of the thermostat assembly (32) to the varying coolant temperature while the decreasement in the heat transmission rate causes late reaction of the thermostat assembly (32) to the varying coolant temperature. The outer surface area of the heat sensitive wax filled body (38.2) is equal to the sum of the contact area (38.3) and the heat transmission area (38.4). The heat transmission area (38.4) is increased by reducing the contact area (38.3) as keeping the total outer surface of the heat sensitive wax filled body (38.2) constant via the ring-shaped cavity (38.5) designed through the bottom contact area (38.3). The cavity (38.5) has a height and a width. Consequently, this thermostat assembly (32) provides a better bypass control to increase efficiency of vehicle engines.

Effective control of the coolant flow between the heat exchange circuit and the bypass circuit maintains optimum engine working temperature. The control is provided by thermostat assembly (32) which connects the two circuits. The heat exchange circuit is the circuit from the radiator inlet (32.2) to outlet (32.3) and includes the radiator (R) channels, engine channels and circulating pump (CP). The bypass circuit is the circuit from the bypass inlet (32.1) to outlet (32.3) and includes just engine channels and circulating pump (CP).

The coolant flow exists from the bypass inlet (32.1) to outlet (32.3) at both fully closed and partially opened thermostat position. The flow from the bypass inlet (32.1) to outlet (32.3) is prevented at fully opened thermostat position. Therefore, the warm coolant is accumulated at the bypass inlet (32.1). The warm coolant accumulated around the heat sensitive wax filled body (38.2) of the thermo- actuator (38) at the fully opened thermostat position prevents the heat sensitive wax filled body (38.2) to sense the real engine coolant temperature in the art of three-way thermostat assembly (32). Thereby the thermostatic valve (10) continues to be in the fully opened position although the engine coolant is cold enough to turn the fully closed thermostatic valve (10) position. Any error about the sense of the engine coolant temperature by the heat sensitive wax filled body (38.2) of the thermo- actuator (38) within the thermostat assembly (32) causes vehicle engines to work inefficiently and be damaged in extreme cases. The present invention provides a thermostat assembly (32) with an improved bypass control even at the fully opened thermostatic valve (10) position. The valve (10) structure of the present invention provides a pilot flow (P) from bypass inlet (32.1) to outlet (32.3) through the conduits (20) designed on the valve (10). The conduits (20) providing pilot flow (P) of the warm coolant prevents the warm coolant accumulation around the heat sensitive wax filled body (38.2) at the fully open thermostat position. Besides, the heat transmission area (38.4) on the heat sensitive wax filled body (38.2) is increased by reducing the contact area (38.3) between the heat sensitive wax filled body (38.2) and the valve (10). This provided with a ring-shaped cavity (38.5) designed through the bottom contact area (38.3). The heat transmission rate from the coolant to the wax is increased through the enlarged heat transmission area (38.4) on the heat sensitive wax filled body (38.2). The increasement in the heat sense rate of the heat sensitive wax filled body (38.2) is resulted in the increasement of thermostat assembly (32) response rate. Consequently, the designed valve (10) structure provides a better bypass control for the engine cooling system.

Explanation of the given figures from 1 to 9 can provide a better understanding of the present invention. The perspective view of valve (10) structure with the conduits (20) on the valve surface (11) and curved valve surface (12) constructed between valve arms (13) is shown in figure 1a. The different perspective views of a thermo-actuator (38) assembly including the valve (10) structure are given in figure 1 b and 1c. Also, a front cross-sectional view of the thermo-actuator (38) assembly with the valve (10) structure is given in figure 1 d. In figure 2a and 2b, two different cross-sectional views of thermo-actuator (38) assembly from different front perspectives are given. The cross-sectional view of the thermostat assembly (32) including the mentioned valve (10) structure and the perspective view of the thermostat assembly (32) of the invention are given respectively in figure 2c and figure 2d. The perspective view of the thermostat assembly (32) includes the bypass inlet (32.1), radiator inlet (32.2) and the outlet (32.3). When the coolant absorbing the excess heat of the engine reaches the first threshold temperature values (35 Centigrade-+2) of the thermostat assembly (32), the wax inside the heat sensitive wax filled body (38.2) starts to expand against to the diaphragm to compensate the increasing hydraulic pressure. The increasement in hydraulic pressure is caused from the temperature increase in wax trapped inside the closed hydraulic reservoir. The closed hydraulic reservoir is constructed by crimping the extension of the heat sensitive wax filled body (38.2) on the extension of the diaphragm. The wax expanding against to diaphragm structure lets the recess of the diaphragm in contact with the hydraulic liquid to move forward. Consequently, the piston (38.1) seated inside the recess from the outer surface of the diaphragm moves forward too. The forward motion of the piston (38.1) results in the raise of the length of the thermo-actuator (38). Thereby this elongation causes the backward motion of the thermo-actuator (38) assembly due to the restriction of the forward motion of the piston

(38.1) end. The restriction is defined with the piston seat (35.2) on the inner surface of the cover (35). The mentioned thermo-actuator (38) assembly consists of the closed heat sensitive wax filled body

(38.2) , the valve (10) structure mounted on the body and a piston (38.1). The spring (37) seated on the body seat (34.2) applies always a forward force against the valve (10) structure by moving through the around of the body nest (34.1). The forward force causes the valve (10) structure to close the radiator inlet (32.2) by setting on the cover seat (35.1). Thereby this provides the maintaining of the coolant flow just from the bypass inlet (32.1) to outlet (32.3) through the bypass circuits at the cold condition of the engine coolant. The fully closed thermostat position allowing coolant flow just through the bypass circuit under the first threshold engine coolant temperature values is shown in the figure 3a.

The diagram of the coolant flow circuit at the fully closed thermostat position is shown in figure 6. The cold coolant forced by the circulation pump (CP) to flow from the bypass inlet (32.1) to outlet (32.3) passes through the bypass circuit including the engine channels in the engine block (E). The coolant absorbing the excess heat of the engine comes again the circulation pump (CP) to be forced to circulate through the circuit again until the coolant temperature reaches the first threshold temperature values.

When the engine coolant reaches enough temperature, the wax pressure forces the piston (38.1) to move forward. The forward motion restriction of the piston (38.1) end due to the piston seat (35.2) causes backward motion of the valve (10) structure. Consequently, the backward motion of the valve (10) pushes back the spring (37) and lets the thermostat assembly (32) starts to partially open. The partially open thermostat position allowing the coolant flow both through the bypass circuit and the exchange circuit is shown in figure 4a.

The diagram of the coolant flow circuit at the partially open thermostat position is shown in figure 7. The warm coolant is forced by the circulation pump (CP) to flow both from the bypass inlet (32.1) to outlet (32.3) and from the radiator inlet (32.2) to outlet (32.3). The coolant flowing from the bypass inlet (32.1) to outlet (32.3) passes through the engine channels in the engine block (E). The coolant flowing from radiator inlet (32.2) to outlet (32.3) passes through both the radiator (R) channels and the engine channels in the engine block (E). The coolant coming again the circulation pump (CP) is forced to circulate through the circuits again until the coolant temperature reaches the second threshold temperature. When the coolant temperature reaches the second threshold temperature values, the thermostat assembly (32) changes position from partially open to fully open. The engine coolant temperature exceeding the second threshold temperature value causes the wax pressure inside the hydraulic system to increase. The high wax pressure forces piston (38.1) to move forward until length of the thermo-actuator (38) reaches its longest state. Thereby the full backward motion of the valve (10) structure thanks to the restricted forward motion of the piston (38.1) end by the piston seat (35.2) forces the spring (37) to push completely back. This phenomenon results in that the thermostat assembly (32) changes position from the partially open to completely open. Thereby the valve (10) structure sits on the body seat (34.2) by insulating the inner wall of the body nest (34.1). So, the coolant flow through the bypass circuit is prevented completely at the fully opened thermostat position in the art. Consequently, this causes the accumulation of the warm coolant around the heat sensitive wax filled body (38.2) at the fully opened position of the thermostat in the art. The accumulated warm coolant prevents heat sensitive wax filled body (38.2) of the thermo- actuator (38) to sense the real engine coolant temperature. Eventually this allows delayed and inaccurate reaction of the thermostat assembly (32).

The coolant flow circuit allowing pilot flow (P) through the bypass circuit via the conduits (10) on the valve (10) structure of the present thermostat assembly (32) at fully opened thermostat position is shown in figure 5a. Unlike the art, the present invention allows both pilot flow (P) through the bypass circuit and the main flow (M) through the heat exchange circuit at the fully opened thermostat position. The designed conduits (20) both on the valve surface (11) and the curved valve surface (12) prevent the accumulation of warm coolant around the heat sensitive wax filled body (38.2) by allowing pilot flow (P) through the bypass circuit. The conduits (20) provides pilot flow (P) from the bypass inlet (32.1) to outlet (32.3).

Briefly, the present invention aims to provide an improved bypass control with the enlarged heat transmission area (38.4) as well as the designed conduits (20) on the valve (10) structure of the present invention. The enlarged heat transmission area (38.4) is provided by reducing the contact area (38.3) between the heat sensitive wax filled body (38.2) and valve (10).

The coolant flow circuit with the pilot flow (P) provided through the conduits (20) designed on the valve (10) structure is shown by the diagram in the figure 8. There is pilot flow (P) from the bypass inlet (32.1) to outlet (32.3) through the bypass circuit as well as the main flow (M) from the radiator inlet (32.2) to the outlet (32.3) through the heat exchange circuit. The exploded perspective view of the thermostat assembly (32) of the present invention including the valve (10) structure of thermo-actuator (38) is given in figure 9. The valve (10) structure has conduits (20) permitting pilot flow (P) during the fully opened thermostat position to prevent the warm coolant accumulation. The accumulated warm coolant causes the heat sensitive wax filled body (38.2) to not sense the main flow (M) temperature at the fully opened thermostat position of the art. This present thermostat assembly (32) shown in figure 12 consists of a body (34), a spring (37), a valve (10) structure, a sealing element (30), a thermo-actuator (38) and lastly a cover (35) to hold mentioned other parts inside. The spring (37) is settled on the body seat (34.2) to apply force the valve (10) structure from the bottom of the valve (10). Thus, the spring (37) pushes the valve (10) structure forward always. The sealing element (30) prevents leakage from outside to inside or from inside to outside of the radiator inlet (32.2) of the thermostat assembly (32) at the fully closed thermostat position.

Claims

The present invention is a three-way thermostat assembly (32) which, comprising a body (34), a spring (37), a valve (10) including valve surface (1 1), a sealing element (30), a thermo- actuator (38) including a heat sensitive wax filled body (38.2) and a piston (38.1), a cover (35), controls the coolant flow between the engine channels and the radiator (R) channels and characterized by; to prevent warm coolant accumulation around the heat sensitive wax filled body for allowing real engine temperature to be sensed by thermo-actuator (38); comprising at least one conduit (20) on the valve surface (1 1), allowing a pilot flow (P) through bypass circuit at fully opened thermostat position.

A thermostat assembly (32) according to claim 1 , and characterized by; to increase the rate of heat transmission occurred between coolant and wax through heat sensitive wax filled body (38.2) for allowing a better reaction rate of cooling system; comprising a cavity (38.5) designed through the bottom contact surface area between the valve (10) structure and the heat sensitive wax filled body (38.2), an enlarged heat transmission area (38.4) provided via said cavity (38.5) which reduces the contact surface area between the heat sensitive wax filled body (38.2) and the valve (10) structure.

A thermostat assembly (32) according to claim 1 or 2, and characterized by; comprising at least one curved valve surface (12) allowing easy coolant flow thereof.

A thermostat assembly (32) according to claim 3, and characterized in that mentioned conduits (20) formed on valve surface (1 1) continue through on mentioned curved valve surfaces (12).

A thermostat assembly (32) according to one of these preceding claims, wherein the assembly may have an embodiment such as two inlets-one outlet: bypass inlet (32.1), radiator inlet (32.2) and outlet (32.3).

6. A thermostat assembly (32) according to one of these preceding claims, wherein mentioned body (34) preserves and holds inside all mentioned parts except the cover (35).

7. A thermostat assembly (32) according to one of these preceding claims and characterized in that; at this preferred embodiment of invention said body (34) has a bypass inlet (32.1) and radiator inlet (32.2).

8. A thermostat assembly (32) according to one of these preceding claims, wherein the mentioned valve (10) structure is mounted on the heat sensitive wax filled body (38.2) of the thermo-actuator (38).

9. A thermostat assembly (32) according to one of these preceding claims, wherein mentioned pilot flow (P) through the bypass circuit is supplied via the channels (20) on both the valve surface (11) and the curved valve surface (12) at the fully opened thermostat position.

10. A thermostat assembly (32) according to one of these preceding claims, wherein the mentioned moving valve (10) structure could sit firmly in a body seat (34.2) at fully opened thermostat position. 11. A thermostat assembly (32) according to one of these preceding claims, wherein the mentioned valve (10) structure could pass through inside of a cylindrical body nest (34.1 ) which starts from the body seat (34.2) on the inner body (34) surface and extends against to inner space of thermostat assembly (32). 12. A thermostat assembly (32) according to one of these preceding claims, wherein the mentioned valve (10) structure passing through the body nest (34.1) sits on the body seat (34.2) at the engine coolant temperature over a second threshold temperature so the closure of the bypass inlet (32.1) allows just a pilot flow (P) through the bypass circuit via the channels (20) on the valve (10) structure.

13. A thermostat assembly (32) according to one of these preceding claims, wherein mentioned spring (37) settled on the inner body (34) surface by passing outside of the body nest (34.1) forces the valve (10) from the bottom valve (10) structure to move always forward.

14. A thermostat assembly (32) according to one of these preceding claims and characterized in that; a wax-based thermo-actuator (38) is used at this preferred embodiment of the invention.

15. A thermostat assembly (32) according to one of these preceding claims, wherein mentioned cover (35) holds the other mentioned parts between the body (34) and itself by closing on the body (34).

16. A thermostat assembly (32) according to claim 15, and characterized by; said cover (35) has a radiator inlet (32.2) at this preferred embodiment of the invention.

17. A thermostat assembly (32) according to one of these preceding claims, wherein the mentioned moving valve (10) could sit firmly inside a cover seat (35.1) located at the radiator inlet (32.2) on the cover (35) inner surface. 18. A thermostat assembly (32) according to one of these preceding claims, wherein the piston (38.1) end could sit firmly inside a piston seat (35.2) located at the radiator inlet (32.2) on the cover (35) inner surface.

19. This invention is a three-way thermostat assembly (32) which controls the coolant flow between the engine channels and the radiator (R) channels in the engine cooling system according to the engine temperature and characterized by removing the accumulated warm coolant around the heat sensitive wax filled body (38.2) at the fully opened thermostat position in the art by allowing a pilot flow (P) via conduits (20) on the valve (10) structure of the thermo- actuator (38) within the present thermostat assembly (32) so the real engine coolant temperature is sensed.

20. This invention is a three-way thermostat assembly (32) which controls the coolant flow between the engine channels and the radiator (R) channels in the engine cooling system according to the engine temperature and characterized by increasing the heat transmission area (38.4) between the heat sensitive wax filled body (38.2) and the coolant via a cavity (38.5) designed through the contact area (38.3) between the heat sensitive body and the valve (10) so the increasement in the heat transmission rate between coolant and wax provides a cooling system which has a better reaction rate.