WO2008078888A1

WO2008078888A1 - Thermostat apparatus

Info

Publication number: WO2008078888A1
Application number: PCT/KR2007/006491
Authority: WO
Inventors: Hee Wan Park
Original assignee: Corea Electronics Corporation; Fuji Bellows Co., Ltd.
Priority date: 2006-12-26
Filing date: 2007-12-13
Publication date: 2008-07-03
Also published as: JP4921955B2; JP2008157194A

Abstract

A thermostat apparatus is disclosed. The thermostat apparatus according to an embodiment of the present invention comprises a cover 36 including a high-temperature coolant inlet port 32, a high-temperature coolant outlet port 34, and a temperature sensitive chamber 30 disposed between the high-temperature coolant inlet port and the high-temperature coolant outlet port; a first housing 42 including a valve seat 38 at a lower part thereof; a second housing 50 including a heater connection port 46 at one lateral side thereof and a low-temperature coolant outlet port 48 at the other lateral side; a temperature sensitive driving unit 52 including a piston shaft 60 extended downward passing through a plug 58; and a valve shaft 70 disposed perpendicularly to the piston shaft 60 of the temperature sensitive driving unit 52 and mounted with a valve 72 elastically supported by a spring 76 and thereby brought into close contact with the valve seat 38 of the first housing 42, so as to control temperature of the engine 78 by supplying low- temperature coolant cooled in the radiator 80 by an opening and closing operation of the valve 72 to the engine. According to this, since the temperature sensitive driving unit 52 is statically mounted in the temperature sensitive chamber 30 formed between the high-temperature coolant inlet port 32 and the high-temperature coolant outlet port 34 of the cover 36 such that the whole surface of the temperature sensitive driving unit 52 is exposed to the high-temperature coolant flowing from the high-temperature coolant inlet port 32 to the high-temperature coolant outlet port 34, the temperature sensitive driving unit 52 is capable of operating the valve shaft 70 by detecting the varied temperature of the high-temperature coolant flowing from the engine 78.

Description

Description THERMOSTAT APPARATUS

Technical Field

[1] The present invention relates to a thermostat apparatus, and more particularly to a thermostat apparatus capable of automatically controlling the temperature of a coolant which cools an engine of a vehicle. Background Art

[2] FIG. 9 and FIG. 10 show a general conventional thermostat apparatus. Referring to

FIG. 9, the conventional thermostat apparatus comprises a housing body 2 constituting a mixing chamber 1, a cover 3 connected to an upper part of the housing body 2, and a temperature sensitive driving unit 4 disposed in the cover 3. The housing body 2 includes a high-temperature coolant port 5 disposed at a lower part thereof and connected to an engine, a coolant sending port 6 disposed at one side thereof and also connected to the engine, and a heater connection port 7 disposed at the opposite side to the coolant sending port 6. A valve seat 8 is formed at one upper side of the high- temperature coolant port 5. Additionally, the cover 3, being connected to a radiator (not shown), includes a connection pipe 10 constituting a low-temperature coolant port 9 and a valve seat 11 formed at one lower side of the low-temperature coolant port 9.

[3] Referring to FIG. 10, the temperature sensitive driving unit 4 includes an extension part 12 extending from a lower part thereof with a reduced diameter, and a lower valve

14 elastically biased downward by a spring 13, being disposed at the lower part thereof, and operated in association with the valve seat 8 of the high-temperature coolant port 5. The temperature sensitive driving unit 4 further includes a piston shaft

15 disposed at an upper end thereof to be extended and contracted in accordance with variation of temperature. An upper end of the piston shaft 15 is supported by a piston shaft supporting unit 16 formed in the connection pipe 10 of the cover 3. A main valve 17 is statically mounted to an upper outer circumference of the temperature sensitive driving unit 4 to operate in association with the valve seat 11 of the cover 3. The above-structured temperature sensitive driving unit 4 is disposed within a mounting frame 18 having a cage form and extended from the cover 3 toward a lower part of the low-temperature coolant port 9. Also, the temperature sensitive driving unit 4 is elastically supported upward by a main spring 20 of which a lower part is supported by a spring seat 19 annularly arranged at a lower end of the mounting frame 18. In addition, a deflector 21 is extended in the coolant sending port 6 by a predetermined height, being disposed in adjacent to the high-temperature coolant port 5.

[4] As shown in FIG. 10, the thermostat apparatus having the above structure shown in FIG. 9 detects temperature of a high-temperature coolant B flowing from an engine 22 to a radiator 23 through a high-temperature coolant line 24 and controls flux of a low- temperature coolant A supplied from the radiator 23 to the engine 22 through a low- temperature coolant line 25, thereby controlling the temperature of the coolant which cools the engine 22. Referring to FIG. 10, the thermostat apparatus is connected between the engine 22 and the radiator 23. At an upper stream of a water pump 26 forcibly supplying the low-temperature coolant A to the engine 22, the low- temperature coolant port 9 and the coolant sending port 6 of the thermostat apparatus are connected to the low-temperature coolant line 25. The high-temperature coolant port 5 is connected with a bypass line 27 diverged from the high-temperature coolant line 24 extended from the engine 22. Additionally, the heater connection port 7 is connected to an outlet of a heater 28 for warming an interior space of a vehicle whereas a heater line 29 diverged from the high-temperature coolant line 24 is connected to an inlet of the heater 28.

[5] In the conventional thermostat apparatus, the low-temperature coolant port 9 flows the low-temperature coolant A, which is cooled from the high-temperature coolant by a cooling unit of the radiator 23, into the mixing chamber 1. The high-temperature coolant port 5 disposed to face the low-temperature coolant port 9 flows the high- temperature coolant B heated by the engine 22 into the mixing chamber 1. The coolant sending port 6 sends a coolant mixture C formed by mixing of the coolants flowing from the low-temperature coolant port 9 and the high-temperature coolant port 5. The temperature sensitive driving unit 4 comprises a thermal expansion member operated in accordance with the temperature of liquid in the mixing chamber 1. The main valve 17 operating in association with the temperature sensitive driving unit 4 controls flux of the low-temperature coolant A flowing from the low-temperature coolant port 9 into the mixing chamber 1. The lower valve 14 operating in association with the temperature sensitive driving unit 4 closes the high-temperature coolant port 5 or controls flux of the high-temperature coolant B flowing from the high-temperature coolant port 5 into the mixing chamber 1.

[6] Thermostat apparatuses structured and operated as described above are disclosed in

JP Utility Model Laid-open No. H02-5672 (entitled Thermostat ), JP Utility Model Laid-open No. H06-37524 (entitled Coolant temperature controlling device of an internal combustion engine ), and JP Utility Model Laid-open No. H10-19160 (entitled Temperature sensitive valve for controlling a coolant circulation circuit of a vehicle engine ).

[7] However, the aforementioned conventional arts have a few drawbacks as follows:

[8] (1) Since the high-temperature coolant port 5 is distanced away from the temperature sensitive driving unit 4 in the mixing chamber 1, the high-temperature coolant B is difficult to reach the temperature sensitive driving unit 4. Therefore, mixing between the low-temperature coolant A and the high-temperature coolant B is not efficiently performed around the temperature sensitive driving unit 4. Therefore, the temperature sensitive driving unit 4 cannot correctly detect temperature of the coolant mixture C and consequently, the temperature of the coolant mixture C for cooling the engine becomes unstable. Furthermore, a variation width of the temperature being controlled according to a varied load of the engine is increased.

[9] (2) Although the mounting frame 18 supports the temperature sensitive driving unit

4, because lateral sides of the temperature sensitive driving unit 4 are transformed by an indentation process for adjusting an inner volume through the transformation, an space between an inner surface of the spring seat 19 of the mounting frame 18 and an outer surface of the temperature sensitive driving unit 4 needs to be secured sufficiently for the indentation process. However, when the interval between the spring seat 19 and the temperature sensitive driving unit 4 is too great, the temperature sensitive driving unit 4 would be seriously shaken by vibration of the engine or pulsation of the coolant, thereby deteriorating the lifespan of the product. Moreover, the main valve 17 and the lower valve 14 integrally formed with the temperature sensitive driving unit 4 may not be operated favorably. Also, detection and control of the coolant temperature would not be performed satisfactorily.

[10] (3) When cutting off the flow of the high-temperature coolant B, the lower valve 14 is compressed by the spring 13 against the valve seat 8 of the high-temperature coolant port 5. However, since such a force of the spring 13 is operated in the form of a pressure load with respect to the temperature sensitive driving unit 4, when the load exerted to the temperature sensitive driving unit 4 is too great, the lifespan of the temperature sensitive driving unit 4 would be shortened. When the pressure exerted to the temperature sensitive driving unit 4 increases, a melting point of the thermal expansion member in the temperature sensitive driving unit 4 is accordingly increased. Therefore, a higher temperature of the coolant is required in order to open the main valve 17 more.

[11] (4) After the high-temperature coolant port 5 is closed, the temperature sensitive driving unit 4 is not able to detect the temperature of the high-temperature coolant B. Accordingly, an opened degree of the main valve 17 is reduced, thereby deteriorating cooling performance of the radiator.

[12] (5) When the high-temperature coolant port 5 is closed, the coolant flow is cut off abruptly. Therefore, temperature hunting occurs right after the closing of the high- temperature coolant port 5. As a result, the temperature of the coolant mixture C becomes unstable. Disclosure of Invention

Technical Problem

[13] Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a thermostat apparatus capable of detecting temperature variation of high-temperature coolant more stably, thereby enabling a more prompt and accurate temperature controlling.

[14] It is another object of the present invention to provide a thermostat apparatus capable of improving durability by reducing pulsation and lateral load of fluid caused by a flow of coolant, eccentric load and lateral load caused by the operation of a spring, running vibration of a vehicle, and lateral load and vibration applied from an engine to a piston of a temperature sensitive driving unit, and consequently improving a controlling accuracy of the coolant temperature.

[15] It is yet another object of the present invention to provide a thermostat apparatus capable of achieving more prompt warming-up during a cold start of the vehicle by reducing unnecessary heat emission on a path by omitting a bypass structure through which the high-temperature coolant operating the temperature sensitive driving unit is returned to the engine, improving an engine cooling efficiency when the engine is overheated since flux to the radiator is increased due to omission of the bypass structure, and saving the product price by omitting the unnecessary bypass structure. Technical Solution

[16] In accordance with the present invention, the above and other objects can be accomplished by the provision of thermostat apparatus comprising a cover including a high-temperature coolant inlet port receiving high-temperature coolant from an engine, a high-temperature coolant outlet port, and a temperature sensitive chamber disposed between the high-temperature coolant inlet port and the high-temperature coolant outlet port; a first housing including a valve seat at a lower part thereof and a low- temperature coolant inlet port at a lateral side thereof; a second housing including a heater connection port at one lateral side thereof and a low-temperature coolant outlet port at the other lateral side; a temperature sensitive driving unit including a wax chamber case, a plug for sealing the wax chamber case, and a piston shaft extended downward passing through the plug; and a valve shaft disposed perpendicularly to the piston shaft of the temperature sensitive driving unit and mounted with a valve elastically supported by a spring and thereby brought into close contact with the valve seat of the first housing, so as to control temperature of the engine by supplying low- temperature coolant cooled in the radiator by an opening and closing operation of the valve to the engine, wherein the temperature sensitive driving unit is statically mounted in the temperature sensitive chamber formed between the high-temperature coolant inlet port and the high-temperature coolant outlet port of the cover such that the whole surface of the temperature sensitive driving unit is exposed to the high- temperature coolant flowing from the high-temperature coolant inlet port to the high- temperature coolant outlet port, in order to operate the valve shaft by detecting the varied temperature of the high-temperature coolant flowing from the engine.

[17] An end of the piston shaft extended from the temperature sensitive driving unit is inserted in the support guiding unit having a pipe form disposed in the center of the first housing, an upper end of the valve shaft is inserted in a lower part of the support guiding unit to unconnectedly contact the piston shaft, a lower end of the valve shaft is inserted in and supported by a bearing part formed at a bottom wall of the second housing, and the spring for achieving tight contact between the valve and the valve seat is disposed between the valve of the valve shaft and the bottom wall of the second housing.

[18] According to another embodiment of the present invention, the thermostat apparatus comprises a single housing opened downward; a support guiding unit integrally extended from the plug of the temperature sensitive driving unit; a pair of bearing supporters extended downward from both inner sides of the housing; and a horizontal supporting base fixed to each one end of the bearing supporters and having a bearing part. The lower end of the piston shaft of the temperature sensitive driving unit and the upper end of the valve shaft unconnectedly contact each other in the support guiding unit, and the lower end of the valve shaft is inserted in the bearing part of the horizontal supporting base. Brief Description of the Drawings

[19] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[20] FIG. 1 is a sectional view showing the structure of a thermostat apparatus according to a first embodiment of the present invention, with a valve in a closed state;

[21] FIG. 2 is a detailed sectional view of a temperature sensitive driving unit constituting the thermostat apparatus according to the embodiment of the present invention;

[22] FIG. 3 is a sectional view of the thermostat apparatus according to the embodiment of the first present invention, with the valve in an opened state;

[23] FIG. 4 is an exploded perspective view of the thermostat apparatus according to the first embodiment of the present invention;

[24] FIG. 5 is an explanatory view of an engine cooling system employing the thermostat apparatus according to the present invention; [25] FIG. 6 is a sectional view of a thermostat apparatus according to a second embodiment of the present invention, with a valve in a closed state;

[26] FIG. 7 is a sectional view taken along a line VII-VII of FIG. 6;

[27] FIG. 8 is an exploded perspective view of the thermostat apparatus according to the second embodiment of the present invention;

[28] FIG. 9 is a sectional view showing the structure of a conventional thermostat apparatus; and

[29] FIG. 10 is an explanatory view of an engine cooling system employing the conventional thermostat apparatus. Best Mode for Carrying Out the Invention

[30] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[31] As shown in FIG. 1, a thermostat apparatus according to the embodiment of the present invention comprises a temperature sensitive chamber 30 formed in the center and opened downward, a cover 36 including a high-temperature coolant inlet port 32 and a high-temperature coolant outlet port 34 on both sides, a first housing 42 holding a cylindrical inner space of which an upper part is fluidly communicated with the temperature sensitive chamber 30, a lower part has a valve seat 38, and a lateral part has a low-temperature coolant inlet port 40, and a second housing 50 holding an inner space of which an upper part is fluidly communicated with the inner space of the first housing 42, a lower part is closed by a bottom wall 44, and one lateral side has a low- temperature coolant outlet port 48 disposed opposite to the heater connection port 46.

[32] A temperature sensitive driving unit 52 is statically mounted in the temperature sensitive chamber 30 of the cover 36. Referring to the detailed sectional view of FIG. 2, the temperature sensitive driving unit 52 includes a wax chamber case 56 in the form of a cap receiving therein a thermal expansion member 54 of a wax type, and a plug 58 sealing the wax chamber casing 56. A piston shaft 60 is inserted from the outside through the plug 56. A rubber sleeve 62 is fixed between the wax chamber case 56 and the plug 58, covering the piston shaft 60 within the wax chamber case 56. The above- structured temperature sensitive driving unit 52 is generally known in the art of the thermostat. As the wax-type thermal expansion member 54 expands and shrinks according to the external temperature, the piston shaft 60 operates in an extending and contracting manner. The temperature sensitive driving unit 52 utilizes the extending and contracting operation of the piston shaft 60.

[33] The whole upper part of the temperature sensitive driving unit 52, which actually performs temperature detection, is disposed in the temperature sensitive chamber 30 of the cover 36. A fixing flange 64 mounted around a lower circumference of the temperature sensitive driving unit 52 is fixed between the cover 36 and the first housing 42. Accordingly, a space between the temperature sensitive chamber 30 and the inner space of the first housing 42 can be isolated from each other, and the temperature sensitive driving unit 52 is stably fixed in the temperature sensitive chamber 30.

[34] A support guiding unit 66 having a pipe form is disposed in the center of the first housing 42 through a supporter member 68 extended from an inner wall of the first housing 42. An end of the piston shaft 60 of the temperature sensitive driving unit 52 is inserted in an upper part of the support guiding unit 66. In addition, an upper end of the valve shaft 70 is inserted in a lower part of the support guiding unit 66 with the piston shaft 60 inserted in the upper part, such that the valve shaft 70 unconnectedly contacts the piston shaft 60. In the middle of the valve shaft 70, a valve 72 is mounted to open and shut the inner spaces of the first housing 42 and the second housing 50 by being separated from and connected with the valve seat 38 of the first housing 42. A lower end of the valve shaft 70 is inserted and supported by a bearing part 74 formed at the bottom wall 44 of the second housing 50. Additionally, a spring 76 is disposed between the valve 72 mounted in the middle of the valve shaft 70 and the bottom wall 44 of the second housing 50 so that the valve 72 is usually maintained in close contact with the valve seat 38.

[35] The thermostat apparatus is provided in a cooling system of an engine 78, as shown in FIG. 5. Referring to FIG. 5, the cooling system of the engine 78 comprises a radiator 80 and a heater 82 for heating an interior of a vehicle. The engine 78 and the radiator 80 are interconnected through a high-temperature cooling line 84 and a low- temperature cooling line 86. Through the high-temperature cooling line 84, a high- temperature coolant circulates from the engine 78 to the radiator 80. Through the low- temperature cooling line 86, a low-temperature coolant circulates from the radiator 80 to the engine 78. The heater 82 is supplied with the high-temperature coolant heated by the engine 78 so that heat radiation is performed to heat the interior of the vehicle. The high-temperature coolant is cooled after the heat radiation and joins the low- temperature coolant in the low-temperature cooling line 86 to be circulated toward the engine 78 through a water pump 88 disposed at the low-temperature cooling line 86.

[36] In the thermostat apparatus according to the embodiment of the present invention, the high-temperature coolant flows from the engine 78 into the high-temperature coolant inlet port 32 through a heater line 90. The high-temperature coolant outlet port 34 is connected to the heater 82. In the cover 36 which includes the temperature sensitive driving unit 52 disposed in the temperature sensitive chamber 30, as the high- temperature coolant flows from the high-temperature coolant inlet port 32 toward the high-temperature coolant outlet port 34, the temperature sensitive driving unit 52 is capable of detecting variation of the temperature of the high-temperature coolant flowing from the engine 78. Thus, as fixed in the temperature sensitive chamber 30 of the cover 36, the temperature sensitive driving unit 52 contacts the high-temperature coolant by the whole surface thereof and therefore is able to stably detect the temperature variation of the high-temperature coolant flowing from the engine 78.

[37] When the temperature of the high-temperature coolant is appropriate for cooling of the engine 78 as a result of detection by the temperature sensitive driving unit 52, the thermal expansion member 54 of the temperature sensitive driving unit 52 does not expand and therefore the piston shaft 60 is not extended. Therefore, whereas the valve shaft 70 unconnectedly contacting the piston shaft 60 by the upper end is not moved down, the valve 72 mounted to the valve shaft 70 is elastically supported upward by the spring 76, thereby being maintained in close contact with the valve seat 38 of the first housing 42. Accordingly, the low-temperature coolant, which is to be supplied from the radiator 80 to the first housing 41 through the low-temperature coolant inlet port 40, cannot be supplied to the low-temperature coolant outlet port 48 of the second housing 50 connected to the low-temperature cooling line 86 of the engine 78, as shown in FIG. 1.

[38] However, when the temperature of the high-temperature coolant is excessively high being inappropriate for cooling the engine 78, the high temperature influences the temperature sensitive driving unit 52 so that the thermal expansion member 54 in the temperature sensitive driving unit 52 is expanded. Accordingly, the rubber sleeve 62 is compressed, thereby extending the piston shaft 60 of which the upper part is inserted in the temperature sensitive driving unit 52. As a consequence, the valve shaft 70 contacting with the piston shaft 60 at the support guiding unit 66 in the first housing 42 is moved down. As the valve 72 mounted to the valve shaft 70 is separated from the valve seat 38, the inner spaces of the inner housing 42 and the second housing 50 are fluidly connected to each other as shown in FIG. 3. In this case, the low-temperature coolant can be supplied from the radiator 80 to the low-temperature coolant inlet port 40 and then supplied to the engine 78 through the low-temperature coolant outlet port 48.

[39] In the conventional thermostat apparatus, high-temperature coolant and low- temperature coolant are mixed and then temperature of the mixed coolant is transmitted to a temperature sensitive driving unit. Due to collision between the high- temperature coolant and the low-temperature coolant on a coolant path, temperature of the coolant mixture is not correctly detected and flow of the coolant is unstable. Meanwhile, in the thermostat apparatus according to the embodiment of the present invention, the temperature sensitive driving unit 52 contacts only the high-temperature coolant in the temperature sensitive chamber 30, and the high-temperature coolant flows out through the high-temperature coolant outlet port 34. Therefore, collision between the high-temperature coolant and the low-temperature coolant does not occur, thereby improving a smooth flow of the high-temperature coolant. Because the temperature variation of only the high-temperature coolant is transmitted, transmission of the temperature variation is more stably performed. Furthermore, since the temperature sensitive driving unit 52 is statically mounted, temperature susceptibility of the temperature sensitive driving unit 52 is guaranteed. Accordingly, a temperature for opening the valve 72, that is, a cooling starting temperature of the engine can be clearly set.

[40] As shown in FIG. 5, in the engine cooling system which applies the thermostat apparatus according to the embodiment of the present invention, the heater 82 is connected to the high-temperature coolant outlet port 34 such that the high-temperature coolant is supplied to the heater 82. However, in a conventional engine cooling system illustrated in FIG. 10, the high-temperature coolant, the temperature of which is detected by the temperature sensitive driving unit 4, is supplied through the bypass line 27 while the heater 28 is supplied with the high-temperature coolant through the heater line 29. Differently from the conventional system, the cooling system adopting the thermostat apparatus according to the embodiment of the present invention totally omits the bypass line, thereby saving the cost incurred by structuring the bypass line. Moreover, since the path of the high-temperature coolant is simplified, undesirable loss of heat on the coolant path can be reduced. As a result, warming-up of the engine can be accomplished more promptly during a cold start, and performance of the heater can be improved. When the engine is hot, the coolant which used to flow to the bypass line in the conventional system is added to the coolant flowing to the radiator, thereby improving the cooling efficiency and stabilizing the temperature of the engine. Consequently, this increases an average temperature of the engine, thereby improving thermal efficiency of the engine and fuel efficiency.

[41] In the thermostat apparatus, the valve shaft 70 mounting the valve 72 is slidably supported at the support guiding unit 66 in the first housing 42 by the upper end thereof, and slidably supported by the bearing part 74 of the second housing 50 by the lower end thereof. Therefore, even when the valve 72 is in an opened state, the thermostat apparatus is not affected greatly by running vibration of the vehicle, vibration by rotation of the engine, lateral load of fluid by flow of the coolant, pulsation of the water pump, and eccentric load by operation of the spring. Thus, the valve 72 can be operated very stably and accordingly, durability of the temperature sensitive driving unit 52 can be improved. As a consequence, the lifespan of the thermostat apparatus can be elongated.

[42] The low-temperature coolant output port 48 of the second housing 50 in which the spring 76 for supporting the valve 72 upward is disposed forms a path for the low- temperature coolant to move toward the water pump 88 when the valve 72 is opened. According to the embodiment of the present invention, the temperature sensitive driving unit 52 is disposed in the temperature sensitive chamber 30 rather than in the path as in the conventional thermostat apparatus, resistance in the path can be reduced. In addition, since the valve shaft 70 of the temperature sensitive driving unit 52 has a small diameter and a simple structure to be supported by the bearing part 74, hydraulic resistance can be reduced.

[43] FIG. 6 and FIG. 7 show a thermostat apparatus according to a second embodiment of the present invention. In the following description, elements the same or similar as those shown in the first embodiment will be cited by the same reference numerals.

[44] The only distinctive features of the second embodiment from the first embodiment are the structure of the housing and the supporting structure of the valve shaft 70. Regarding the other parts, the first and second embodiments are structured in the same manner.

[45] In the first embodiment, the housing comprises the first housing 42 and the second housing 50 and the first housing 42 has the valve seat 38 at the lower part. On the other hand, in the second embodiment, the housing comprises an integrated housing 42a corresponding to the first housing 42 of the first embodiment whereas the second housing 50 is omitted. The valve seat 38 is disposed in the center of the housing 42a. The heater connection port 46 is formed at a lower part of the valve seat 38. The low- temperature coolant outlet port 48 is opened downward.

[46] In the second embodiment, the support guiding unit 66 supporting the valve shaft

70 in the first embodiment is omitted. Instead, a support guiding unit 66a is formed by elongating a lower part of a plug 58 constituting the temperature sensitive driving unit 52. The lower end of the piston shaft 60, being extended from the inside of the temperature sensitive driving unit 52, and the upper end of the valve shaft 70 un- connectedly contact with each other in the support guiding unit 66a. In addition, because the low-temperature coolant outlet port 48 of the second embodiment is formed by an opened lower part of the housing 42a, the bearing part 74 as in the first embodiment cannot be provided. Therefore, in order to support the lower end of the valve shaft 70, a pair of bearing supporters 92 and 92 are extended downward from both sides of an inner wall of the housing 42a adjoining the valve seat 38. Additionally, a horizontal bearing base 94 is fixed at lower ends of the bearing supporters 92 and 92 . A bearing part 96 is structured in the center of the horizontal bearing base 94 to support the valve shaft 70 by receiving the lower end of the valve shaft 70.

[47] As apparent from the above description, the second embodiment is advantageous in terms of the simplified housing 42a compared to the housing of the first embodiment. Also, according to the second embodiment, the upper end of the valve shaft 70 mounted with the valve 72 is supported by the support guiding unit 66a integrally extended from a lower part of the plug 58 of the temperature sensitive driving unit 52 in a sliding manner, and the lower end of the valve shaft 70 is supported by the bearing supporters 92 and 92 extended from the inner wall of the housing 42a and the horizontal bearing base 94 fixed to the ends of the bearing supporters 92 and 92 . In addition, the valve shaft 70 is supported by the bearing part 96 formed in the center of the horizontal bearing base 94 in a sliding manner, and the spring 76 is disposed between the valve 72 and the horizontal bearing base 94 to support the valve shaft 70 upward. Thus, the second embodiment is capable of supporting the valve shaft 70 as stably as in the first embodiment.

[48] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

[1] A thermostat apparatus comprising: a cover 36 including a high-temperature coolant inlet port 32 receiving high- temperature coolant from an engine 78, a high-temperature coolant outlet port 34, and a temperature sensitive chamber 30 disposed between the high- temperature coolant inlet port and the high-temperature coolant outlet port; a first housing 42 including a valve seat 38 at a lower part thereof and a low- temperature coolant inlet port 40 at a lateral side thereof; a second housing 50 including a heater connection port 46 at one lateral side thereof and a low-temperature coolant outlet port 48 at the other lateral side; a temperature sensitive driving unit 52' including a wax chamber case 56, a plug 58 for sealing the wax chamber case, and a piston shaft 60 extended downward passing through the plug; and a valve shaft 70 disposed perpendicularly to the piston shaft 60 of the temperature sensitive driving unit 52 and mounted with a valve 72 elastically supported by a spring 76 and thereby brought into close contact with the valve seat 38 of the first housing 42, so as to control temperature of the engine 78 by supplying low-temperature coolant cooled in the radiator 80 by an opening and closing operation of the valve 72 to the engine, wherein the temperature sensitive driving unit 52 is statically mounted in the temperature sensitive chamber 30 formed between the high-temperature coolant inlet port 32 and the high-temperature coolant outlet port 34 of the cover 36 such that the whole surface of the temperature sensitive driving unit 52 is exposed to the high-temperature coolant flowing from the high-temperature coolant inlet port 32 to the high-temperature coolant outlet port 34, in order to operate the valve shaft 70 by detecting the varied temperature of the high-temperature coolant flowing from the engine 78.

[2] The thermostat apparatus according to claim 1, wherein an end of the piston shaft

60 extended from the temperature sensitive driving unit 52 is inserted in the support guiding unit 66 having a pipe form disposed in the center of the first housing 42, an upper end of the valve shaft 70 is inserted in a lower part of the support guiding unit 66 to unconnectedly contact the piston shaft 60, a lower end of the valve shaft 70 is inserted in and supported by a bearing part 74 formed at a bottom wall 44 of the second housing 50, and the spring 76 for achieving tight contact between the valve and the valve seat 38 is disposed between the valve 72 of the valve shaft 70 and the bottom wall of the second housing 50.

[3] The thermostat apparatus according to claim 1, comprising: a single housing 42a opened downward; a support guiding unit 66a integrally extended from the plug 58 of the temperature sensitive driving unit 52; a pair of bearing supporters 92 and 92' extended downward from both inner sides of the housing 42a; and a horizontal supporting base 94 fixed to each one end of the bearing supporters 92 and 92' and having a bearing part 96, the thermostat apparatus structured in such a manner that the lower end of the piston shaft 60 of the temperature sensitive driving unit 52 and the upper end of the valve shaft 70 unconnectedly contact each other in the support guiding unit 66a, and the lower end of the valve shaft 70 is inserted in the bearing part 96 of the horizontal supporting base 94.