CN111164283A

CN111164283A - Thermostat assembly without direct or indirect cooling of heat sensitive wax fill when fully closed

Info

Publication number: CN111164283A
Application number: CN201880062317.4A
Authority: CN
Inventors: F·安鲁斯兰
Original assignee: Kirpart Otomotiv Parcalari Sanayi ve Ticaret AS
Current assignee: Kirpart Otomotiv Parcalari Sanayi ve Ticaret AS
Priority date: 2017-09-26
Filing date: 2018-09-18
Publication date: 2020-05-15
Also published as: WO2019066759A1; IL273566A; EP3714141A1; TR201714314A2

Abstract

The present invention relates to a thermostat assembly (30) that utilizes a non-thermally conductive valve structure (10) mounted on a thermally sensitive wax fill (38.2) and a sealing element (20) located in a recess (11) in the top of the non-thermally conductive valve structure (10) to prevent indirect or direct cooling of the thermally sensitive wax fill (38.2) of a thermal actuator (38) within the thermostat assembly (30) when the thermostat is in a fully closed position.

Description

Thermostat assembly without direct or indirect cooling of heat sensitive wax fill when fully closed

Technical Field

The present invention relates to a thermostat assembly for use in an engine cooling system, and in particular to improvements in the temperature control of the cooling system.

In the prior art, the radiator inlet is closed by moving the valve structure when the thermostat is in a fully closed position, thereby preventing relatively cold coolant in the radiator inlet passage from impinging on the thermal wax fill. Thus, relatively cool coolant accumulates at the radiator inlet passage. Despite the closed radiator inlet, there is still heat transfer between the relatively cool coolant and the thermal wax fill. In the prior art, the extension of the thermal wax filling forms a valve structure to close the radiator inlet, resulting in heat transfer between the relatively cool coolant flowing through itself and the thermal body. This phenomenon causes the heat sensitive body to be indirectly affected by the accumulation of relatively cool coolant in the inlet passage of the radiator when the thermostat is in the fully closed position. The heat sensitive body, which is indirectly influenced by the relatively cold coolant, cannot detect the actual temperature of the coolant of the recirculating bypass circuit and will act on the basis of inaccurate temperature information. This renders the temperature control of the engine cooling system less accurate.

The present invention provides a thermostat assembly that does not directly or indirectly cool a thermally sensitive wax fill when the thermostat is in a fully closed position. Unlike the valve structures of thermostat assemblies of the art, the valve structure of the present invention is made of a compound having a low thermal conductivity, such as rubber or plastic. The rubber or plastic valve structure prevents heat transfer between the thermal wax fill and the relatively cool coolant in the radiator inlet channel. Furthermore, the sealing element on the valve structure of the present invention prevents the aforementioned leakage of cooler coolant from the radiator inlet passage onto the heat sensitive body by providing a seal at the radiator inlet when the thermostat is in the fully closed position.

Background

None of the technologies can completely convert chemical energy in the fuel of an internal combustion engine into mechanical energy. Most of the chemical energy is lost as heat energy generated between moving parts and as friction energy. And the friction energy is also converted into heat energy finally. Thus, inefficiencies in the conversion of energy from chemical to mechanical can result in the accumulation of excess heat on the engine and engine components. In extreme cases, the excess heat can cause engine-end engine component damage.

The engine of the vehicle is convenient to operate when the engine is within a certain temperature range corresponding to its optimum efficiency. Therefore, proper cooling of the engine and engine components is very important for the vehicle. The cooling operation is provided by an engine cooling system of the vehicle.

The engine cooling system has two sub-circuits interconnected by a thermostat assembly. The first coolant circulation circuit is referred to as a bypass circuit, which passes through the circulation pump and the engine passage when the engine coolant temperature is sufficiently cold (below a first threshold temperature). The aforementioned engine passages include a passage through the crankcase and a passage through the crankcase cover. When the engine coolant temperature is sufficiently hot (above the aforementioned first threshold temperature), the coolant also starts flowing through the second coolant circulation circuit. The aforementioned second coolant circulation circuit is referred to as a heat exchange circuit, which passes through the radiator passage including the radiator fin and the aforementioned circulation pump and engine passage. Excess heat from the engine and engine components is absorbed by the coolant flowing through the engine passages, and when the temperature of the recirculated engine coolant is very high (above a second threshold temperature), the bypass loop flow will no longer be present. At this time, the coolant flows only through the heat exchange circuit and is cooled by wind and an additional air flow that forces air to flow over the fins of the radiator by the axial flow fan. Thus, excess heat is absorbed by the finned radiator channels and is removed from the engine and engine components and released to the environment. The thermostat assembly described above controls the flow of coolant through the sub-circuits at different rates based on the temperature of the coolant in the engine passages to maintain optimal engine operating temperatures. Thus, an example thermostat assembly should be capable of conveniently controlling the aforementioned flow rate. Such thermostats are typically at least in the form of a three-way valve to enable a change in communication relationship, where the first is from the engine passage, the second is from the radiator passage, and finally the third is into the engine passage.

The thermal actuator within the thermostat assembly described above includes a thermally sensitive wax fill body, a valve structure mounted on the body described above, and a movable piston. The aforementioned thermal wax filling body is a hydraulic system constructed by caulking a heat conductive container and an elastic rubber diaphragm, and a hydraulic fluid called a wax compound is provided inside the hydraulic system. The aforementioned piston is inserted outwardly into the recess of the diaphragm. The aforementioned temperature difference between the hydraulic liquid and the recirculating engine coolant will result in a heat transfer through the heat conducting heat accumulating surface in contact with both the coolant and the hydraulic liquid. This heat transfer continues until the temperature of the hydraulic fluid equals the temperature of the recirculated engine coolant. Wherein the temperature of the recirculated engine coolant is detected by the thermal wax filling body. This means that an increase in the temperature of the recirculated engine coolant will result in an increase in the temperature of the hydraulic fluid, and likewise a decrease in the temperature of the recirculated engine coolant will result in a decrease in the temperature of the hydraulic fluid.

When the thermal actuator is in the closed position, the engine coolant temperature enables efficient engine operation. In this closed position, the length of the thermal actuator is minimal. During the closed position of the thermal actuator, the valve structure mounted on the thermal wax filling closes the radiator inlet of the aforementioned thermostat assembly, which prevents relatively cold coolant from flowing from the radiator passage to the engine passage. Thus, the recirculated engine coolant continues to flow only in the first coolant circulation circuit, and such a thermostat position that allows only engine coolant to flow through the bypass circuit is referred to as a thermostat fully closed position.

When the engine coolant temperature is high enough (reaches a first threshold), the wax in the thermal wax fill begins to expand and the increase in hydraulic fluid volume causes the elastomeric diaphragm structure to contract, which moves the piston forward. However, because of the structure that limits forward movement of the piston end, the piston end is no longer moving forward and the thermal wax filling and engaged valve structure move rearward.

When the engine coolant temperature reaches a maximum temperature value (second threshold) defined for the thermostat assembly, the thermal actuator within the thermostat assembly will also reach its maximum length, thereby allowing the valve structure to close the bypass inlet. The closing of the bypass inlet allows all the coolant to flow only through the second coolant circulation circuit, which includes the radiator channel and the engine channel, and which is called the heat exchange circuit. Thereby, the engine coolant continues to circulate in the second coolant circulation circuit until the coolant temperature again falls below the second threshold engine temperature. The position of the thermostat assembly where engine coolant is caused to flow only through the heat exchange circuit is referred to as the thermostat fully open position.

The thermostat assembly allows engine coolant to flow in both coolant circulation loops when the length of the thermal actuator is between a maximum and a minimum, and the position of the thermostat assembly that allows engine coolant to flow through the bypass loop and the heat exchange loop is referred to as the thermostat partially open position.

When the temperature of the cooling fluid flowing through both the first circulation circuit and the second circulation circuit drops below the first threshold temperature, the temperature of the hydraulic liquid in the thermal wax filling will also drop due to heat transfer between the cooling fluid and the hydraulic liquid, which will result in a drop in hydraulic liquid pressure. The hydraulic liquid contraction due to the pressure drop will thus cause a reduction in the volume of the hydraulic liquid, which will result in a backward movement of the diaphragm structure, so that the piston inserted into the recess of the diaphragm will also move backwards. The thermal actuator then again changes to its minimum length value, causing the thermostat assembly's radiator inlet to close.

The thermostat assembly of the art is in a fully closed position, and the thermal wax fill is indirectly affected by the relatively cooler coolant in the radiator inlet passage, despite the radiator inlet being closed by the valve structure. The thermally conductive valve structure of the thermostat assembly formed by the elongation of the heat sensitive body will result in an indirect heat exchange between the relatively cool coolant and the hydraulic fluid in the heat sensitive body when the radiator inlet is closed. There should not be any heat transfer between the cooler coolant in the radiator inlet channel and the hydraulic fluid in the thermal sensitive body when the thermostat assembly is in the fully closed position, so that the thermal sensitive wax filling body can more accurately detect the temperature of the coolant.

The purpose of document US5727729 is to prevent relatively cold coolant from impinging directly on the thermal wax filling when entering the thermostat assembly from the bottom hose of the radiator (radiator inlet) when the thermostat is in the fully open position, and it has two valve members connected to a temperature-responsive valve actuation device. The first valve member is used to regulate the flow of coolant from the radiator inlet to the outlet, and the second valve member is used to regulate the flow from the bypass inlet to the outlet. The aforementioned first valve member is arranged to extend outwardly from the aforementioned valve actuator assembly such that relatively cool coolant entering the thermostat assembly through the radiator inlet passage is kept away from the thermal wax filling within the valve actuator assembly. However, even if the radiator inlet is fully closed, the thermostat assembly is still indirectly affected by the relatively cooler coolant in the radiator inlet passage due to the presence of the first valve member. Even in the thermostat fully closed position, communication (heat transfer) between the hydraulic fluid in the thermal wax fill and the relatively cooler coolant in the radiator inlet passage is maintained due to the thermally conductive nature of the first valve member extending from the thermal wax. The first valve member extension is thermally conductive such that hydraulic fluid within the thermal wax fill is indirectly affected by the relatively cooler coolant within the bottom radiator hose. This indirect cooling of the thermal wax fill with the hydraulic fluid, caused by the relatively cool cooling in the bottom radiator hose, will prevent the thermostat assembly from sensing the actual temperature of the engine coolant flowing through the engine gallery when the thermostat is in the fully closed position.

In summary, there is no thermostat known in the prior art that prevents relatively cold coolant in the radiator inlet passage from indirectly cooling the thermal wax fill when in the fully closed position. Therefore, a solution of the present invention is needed.

Disclosure of Invention

It is an object of the present invention to provide a thermostat assembly that prevents the thermal wax fill of a thermal actuator from being directly or indirectly affected by the relatively cooler coolant in the inlet passage of a radiator when the thermostat is in a fully closed position. Thermostat assemblies in the art have a valve structure formed by a valve element extending from a thermally sensitive wax fill body. Thus, heat transfer between the heat sensitive body and the aforementioned relatively cool coolant in the aforementioned radiator inlet passage continues through the thermally conductive valve element of the valve structure even when the thermostat is in the fully closed position.

The present invention provides a thermostat assembly wherein the rubber or plastic valve structure mounted on the thermal wax filling does not allow any indirect heat transfer between the aforementioned relatively cool coolant in the radiator inlet passage and the thermal body, while the sealing element on the valve structure does not allow any direct heat transfer, when the thermostat is in the fully closed position. The present invention thus ensures that the heat sensitive body can only detect the temperature of the recirculating engine coolant when the thermostat is in the fully closed position. Unlike engine cooling systems having thermostat assemblies of the prior art, the present invention provides an engine cooling system that can operate more accurately.

Drawings

FIG. 1a is a perspective view of the sealing element and valve structure of the thermostat assembly of the present invention wherein the top of the valve structure has a recess to facilitate the installation of the sealing element.

Fig. 1b is a perspective view of the valve structure of the present invention, wherein the aforementioned sealing element is located on the aforementioned groove.

Fig. 2a and 2b are perspective views of the valve structure of the present invention mounted on a thermal actuator.

Figure 2c is a cross-sectional view of the valve structure of the present invention mounted on a thermal actuator.

FIG. 3 is a cross-sectional view of the thermostat assembly of the present invention in a fully closed position.

FIG. 4 is an exploded perspective view of an embodiment of the thermostat assembly of the present invention.

FIG. 5 is a cross-sectional view of a prior art thermostat assembly showing a valve structure formed by an extension of a thermally sensitive wax fill, whereby heat transfer between the thermally sensitive wax fill and the relatively cool coolant in the radiator inlet passage will continue indirectly through the thermally conductive valve structure even though the thermostat is in a fully closed position, since the valve structure is an extension of the thermal actuator wax fill within a conventional thermostat assembly.

Reference numerals

10. Valve structure

11. Trough

20. Sealing element

30. Thermostat assembly

31. Bypass inlet

32. Radiator inlet

33. An outlet

34. Main body

35. Cover body

36. Valve body seat

37. Spring

38. A thermal actuator.

Detailed Description

The invention provides a thermostat assembly (30) having a non-thermally conductive valve structure (10) and a sealing element (20) on top of the aforementioned valve structure (10) to prevent direct or indirect cooling of a thermally sensitive wax fill (38.2) when the thermostat is in a fully closed position.

The purpose of closing the radiator inlet (32) is to prevent relatively cold coolant from flowing from the radiator passage to the engine passage when the temperature of the recirculated engine coolant reaches a temperature that is favorable for efficient engine operation.

While the closure of the radiator inlet (32) prevents relatively cold coolant from impinging directly on the thermal wax filling (38.2) to flow through the heat exchange circuit when the thermostat is in the fully closed position, the prior art valve arrangement (10) is formed by an extension of the thermal wax filling (38.2) which causes the thermal wax filling (38.2) to be indirectly influenced by the relatively cold coolant in the radiator inlet (32) passage. Thus, the thermal wax filling (38.2) cannot detect the actual engine coolant temperature and, in extreme cases, can also cause the coolant in the engine gallery to boil.

The present invention provides a thermostat assembly (30) with improved valve control that prevents direct and indirect cooling of a thermal wax fill (38.2) when the thermostat is in a fully closed position. The aforementioned valve structure (10) of the present invention prevents direct and indirect heat transfer between the thermal wax fill (38.2) and the relatively cool coolant in the radiator inlet (32) passage when the thermostat is in a fully closed position. An annular sealing element disposed in an annular recess (11) in the valve structure (10) joins the valve body seat (36) to the inner surface of the cover (35) to effect sealing of the radiator inlet (32), whereby leakage of coolant from the radiator inlet (32) passage to the thermal wax filler (38.2) and engine passage is relatively low. Furthermore, in the prior art, the situation that the thermo wax filling body (38.2) is indirectly cooled due to the heat transfer between the relatively cold cooling liquid in the radiator inlet (32) channel and the thermo wax filling body (38.2) through the heat-conducting valve structure (10) can be prevented by the valve structure (10) made of the non-heat-conducting material in the embodiment. Furthermore, the aforementioned sealing element (20) is also made of a non-heat-conducting material. Thus, the thermostat assembly (30) of the present invention, including the aforementioned valve structure (10) and the aforementioned sealing element (20) on the aforementioned valve structure (10), provides an engine cooling system with better temperature control, which is capable of operating based solely on recirculated engine coolant temperature.

The contents of the figures of fig. 1 to 5 may provide a better understanding of the invention. Fig. 1a shows a perspective view of the aforementioned sealing element (20) and the aforementioned valve structure (10) comprising the aforementioned groove (11) structure. Fig. 1b shows a perspective view of the aforementioned sealing element (20) in combination with the aforementioned valve arrangement (10).

In fig. 2a and 2b different perspective views of the aforementioned valve structure (10) mounted on a thermal actuator (38) are shown. In fig. 2c a cross-sectional view of the aforementioned valve structure (10) mounted on a thermal actuator (38) is shown.

A cross-sectional view of the thermostat assembly (30) in a fully closed position is shown in fig. 3. Although the thermostat assembly (30) described above in fig. 3 has three passages: a bypass inlet (31), a radiator inlet (32) and an outlet (33), but in other embodiments the valve structure (10) of the present embodiment may be used with all other forms of thermostat assemblies.

With the valve structure (10) provided on the valve body seat (36) provided in this embodiment, cold coolant is prevented from flowing from the radiator inlet (32) onto the thermal wax filling (38.2) when the thermostat is in the fully closed position. Furthermore, leakage of coolant, which occurs in the prior art due to the aforementioned gap between the valve structure (10) and the valve seat (36), can be prevented by the sealing element (20) mounted on the groove (11) of the aforementioned valve structure when the thermostat is in the fully closed position. The material of the sealing element (20) is more resilient than both the valve structure (10) and the cover (35), so that the sealing element (20) provides a high seal by extending into all gaps between the valve structure (20) and the valve seat (36) when the thermostat is in the fully closed position. Moreover, unlike the thermally conductive valve structure (10) of the prior art thermostat assembly (30), the present embodiment provides both the valve structure (10) and the aforementioned sealing element (20) that are made of a non-thermally conductive material. Fig. 4 shows an exploded perspective view of the thermostat assembly (30) of the invention, fig. 4 showing the valve structure (10) with the groove (11) structure and the sealing element (20) to be disposed on the groove at an assembly stage.

A cross-sectional view of a prior art thermostat assembly (30) having a thermally conductive valve structure (10) formed by an extension of a thermally sensitive wax filling (38.2) is shown in fig. 5. In fact, the primary purpose of all valve configurations (10) is to close the radiator inlet (32) when the thermostat is in a fully closed position, thereby preventing heat transfer through the radiator inlet (32). Although the prior art valve structure (10) formed by the extension of the thermal wax filling (38.2) may prevent direct heat transfer through the radiator inlet (32) when the thermostat is in the fully closed position, there is still indirect heat transfer entering from the radiator inlet (32) through the thermally conductive valve structure (10). In the prior art, the thermally conductive valve structure (10) formed by the extension of the thermal wax filling (38.2) would result in heat transfer between the thermal wax filling (38.2) and the relatively cool coolant in the radiator inlet (32) channel.

Claims

1. A thermostat assembly (30) having a body (34), a spring (37), a thermal actuator (38) assembly, a valve body seat (36) and a cover (35) for providing an improved bypass control of coolant flow between an engine passage and a radiator passage in an engine cooling system as a function of engine temperature for improved engine efficiency, characterized by preventing heat transfer between the thermally sensitive wax filling (38.2) and relatively cooler coolant in a radiator inlet (32) passage when the thermostat is in a fully closed position, comprising:

a valve structure (10) having an annular recess (11) in a top surface; and

a sealing element (20) arranged in the groove (11),

wherein direct heat transfer is prevented by the sealing element (20) in combination with the valve seat (36), and indirect heat transfer is prevented by making the valve structure (20) provided with the sealing element (20) of a non-heat conducting material.

2. The thermostat assembly (30) of claim 1, wherein:

wherein the sealing element (20) and the valve structure (10) are made of rubber or plastic for preventing heat transfer between the thermo wax filling (38.2) and the relatively cold coolant in the radiator inlet (32) channel, such that the coolant flow circulates only via the bypass circuit when the thermostat is in a fully closed position.