Patent Publication Number: US-8973537-B2

Title: Engine having thermostat and system thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority of Korean Patent Application Number 10-2012-0155365 filed Dec. 27, 2012, the entire contents of which application are incorporated herein for all purposes by this reference. 
     BACKGROUND OF INVENTION 
     1. Field of Invention 
     The present invention relates to an engine having a thermostat and a system thereof that actively control a temperature of a coolant by converting a flow channel of the coolant according to a temperature of the coolant that is circulated to prevent overheating. 
     2. Description of Related Art 
     A vehicle thermostat is installed between an engine and a radiator and maintains a coolant in a predetermined temperature range by adjusting a flux flowing to a radiator while being automatically opened and closed according to a temperature change of a coolant. 
     In a mechanical thermostat, a wax expands according to a temperature of a coolant, and a piston causes an opening and closing displacement of a valve by such an expansion force. 
     Such a mechanical thermostat operates according to an opening and closing temperature that is set to a predetermined temperature, simply opens and closes only in a predetermined temperature, and does not actively cope with a change such as driving circumstances or a situation of a vehicle. 
     An electronic thermostat for maintaining a coolant temperature of an engine to an optimal state while supplementing a drawback of a mechanical thermostat is suggested. 
     Such an electronic thermostat can maintain an optimal coolant temperature by actively controlling a coolant temperature of an engine according to a driving environment such as a load state of a vehicle and can obtain a fuel consumption improvement effect and an exhaust gas reduction effect, compared with a mechanical thermostat. 
     In order to open and close a valve of the thermostat, a temperature sensitive type and electronically actively controlled driver is applied, and such a driver includes a wax, a half fluid, a rubber piston, a backup plate, and a main piston. 
     Here, the wax, the half fluid, the rubber piston, the backup plate, and the main piston are sequentially disposed in a length direction to form a sealing structure, and the main piston moves in the front-rear direction according to expansion of the wax. 
     In a cold state, the coolant does not circulate a radiator and is heated by circulating a bypass of the thermostat and the engine. 
     However, in order to reduce fuel consumption and to improve a quality of an exhaust gas, a research of more quickly hitting a coolant has been continued. 
     The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     SUMMARY OF INVENTION 
     The present invention has been made in an effort to provide an engine having a thermostat and a system thereof having advantages of reducing fuel consumption and improving a quality of an exhaust gas by more quickly heating a temperature of a coolant that circulates an engine and a thermostat. 
     Various aspects of the present invention provide an engine system having a thermostat, the system including: a thermostat casing that has one side connected to a first flow channel, the other side connected to a second flow channel, and a wall between the one side and the other side connected to third and fourth flow channels, a valve guide in which a main valve that opens and closes the first flow channel is formed at one side, a closing valve that opens and closes the second flow channel is formed at the other side, and a bypass valve is formed adjacent to the closing valve, an elastic member that elastically supports the valve guide to enable the main valve to block the first flow channel and the closing valve to block the second flow channel, a driver that moves the valve guide so that the main valve opens the first flow channel and the closing valve opens the second flow channel according to a temperature of a coolant, and a control unit that controls the temperature and a flow of the coolant by controlling the driver. 
     The control unit may control the closing valve to block the second flow channel when the main valve blocks the first flow channel. 
     The first flow channel may be a radiator exhaust flow channel that is connected to a radiator, the second flow channel may be an engine exhaust flow channel that is connected to one side of an engine, the third flow channel may be an engine inflow flow channel that is connected to the other side of the engine, and the fourth flow channel may be a heater exhaust flow channel that is connected to a heater. 
     The driver may include a wax that is filled in a wax case and contracts or expands according to a temperature, and a main piston that moves the valve guide in a front-rear direction by expansion of the wax. 
     When the main valve blocks the first flow channel and the closing valve blocks the second flow channel, the control unit may control the coolant so that the coolant circulates the engine, the heater and the thermostat through the heater exhaust flow channel and the engine inflow flow channel. 
     The control unit may control the heater to heat the coolant, if the temperature of the coolant is lower than a predetermined value. 
     The bypass valve may be formed at a predetermined distance toward the main valve from the closing valve, and when the driver does not move the valve guide, the control unit may control the main valve to close the first flow channel and the closing valve to close the second flow channel, and when the driver moves the valve guide in a predetermined intermediate operation state, the control unit may control the main valve to open the first flow channel and the closing valve to open the second flow channel, and when the driver moves the valve guide in a predetermined maximum operation state, the control unit may control the main valve to open the first flow channel to the maximum and the bypass valve to close the second flow channel. 
     The control unit may stop operation of the heater and block the flow of the coolant that is supplied to the heater through a heating line adjustment valve, if the temperature of the coolant is equal to or larger than a predetermined value. 
     The control unit may operate the heater and adjust the flow of the coolant that is supplied to the heater through a heating line adjustment valve, if the temperature of the coolant is less than a predetermined value. 
     Various other aspects of the present invention provide an engine having a thermostat, the engine including: a thermostat casing that has one side connected to a first flow channel, the other side connected to a second flow channel, and a wall between the one side and the other side connected to third and fourth flow channels, a valve guide in which a main valve that opens and closes the first flow channel is formed at one side, a closing valve that opens and closes the second flow channel is formed at the other side, and a bypass valve is formed adjacent to the closing valve, an elastic member that elastically supports the valve guide to enable the main valve to block the first flow channel and the closing valve to block the second flow channel, a driver that moves the valve guide so that the main valve opens the first flow channel and the closing valve opens the second flow channel according to a temperature of a coolant. 
     The closing valve may block the second flow channel when the main valve blocks the first flow channel. 
     The driver may include a wax that is filled in a wax case and contracts or expands according to a temperature, and a main piston that moves the valve guide in a front-rear direction by expansion of the wax. 
     When the main valve blocks the first flow channel and the closing valve blocks the second flow channel, the coolant may circulate the engine, the heater and the thermostat through the heater exhaust flow channel and the engine inflow flow channel. 
     The bypass valve may be formed at a predetermined distance toward the main valve from the closing valve, and when the driver does not move the valve guide, the main valve may close the first flow channel and the closing valve may close the second flow channel, and when the driver moves the valve guide in a predetermined intermediate operation state, the main valve may open the first flow channel and the closing valve may open the second flow channel, and when the driver moves the valve guide in a predetermined maximum operation state, the main valve may open the first flow channel to the maximum and the bypass valve may close the second flow channel. 
     In an engine system having a thermostat of the present invention, in a state in which a first flow channel that is connected to a radiator is blocked in a thermostat casing, by blocking a second flow channel that is connected an engine and by enabling a coolant to circulate an engine, a heater, and a thermostat, a temperature of the coolant can be more quickly heated. Therefore, fuel consumption can be reduced, and a quality of an exhaust gas can be further improved. 
     The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an exemplary engine system having an exemplary thermostat according to the present invention. 
         FIG. 2  is a cross-sectional view illustrating an entire structure of an exemplary thermostat according to the present invention. 
         FIG. 3  is a cross-sectional view illustrating a structure of an exemplary thermostat according to the present invention. 
         FIG. 4  is a cross-sectional view illustrating three operation states of an exemplary thermostat according to the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims. 
       FIG. 1  is a schematic diagram of an engine system having a thermostat according to various embodiments of the present invention. Referring to  FIG. 1 , the engine system having a thermostat includes an engine  130 , a thermostat  100 , a heater  120 , an engine exhaust flow channel  122 , an engine inflow flow channel  128 , a heater exhaust flow channel  124 , a radiator exhaust flow channel  126 , and a heating line adjustment valve  150 . 
     Further, the thermostat  100  includes a thermostat case  140 , and the thermostat case  140  is connected to the engine exhaust flow channel  122 , the heater exhaust flow channel  124 , the radiator exhaust flow channel  126 , and the engine inflow flow channel  128 . 
     A coolant is used for cooling the engine  130 , and when a temperature of the coolant is lower than a predetermined value, the thermostat  100  enables a coolant to circulate the heater  120  and the engine  130 . 
     When a temperature of the coolant is higher than a predetermined value, the thermostat  100  enables a coolant to circulate the engine  130  and a radiator  110 . 
     In more detail, a cold coolant circulates through the heater  120 , the heater exhaust flow channel  124 , the thermostat  100 , and the engine inflow flow channel  128 , and a coolant is quickly heated through the heater  120 . 
     In various embodiments of the present invention, the heating line adjustment valve  150  may be installed in the heater exhaust flow channel  124 , and the heating line adjustment valve  150  selectively supplies a coolant to the heater  120 . 
     Further, a hot coolant circulates the radiator  110 , the thermostat  100  and the engine  130 , and a coolant is cooled through the radiator  110 . 
       FIG. 2  is a cross-sectional view illustrating an entire structure of a thermostat and  FIG. 3  is a cross-sectional view illustrating a structure of a thermostat according to various embodiments of the present invention. 
     A detailed description of constituent elements identical to or similar to those described in  FIG. 1  will be omitted. 
     Referring to  FIGS. 2 and 3 , the thermostat  100  includes a main valve  240 , a wax case  207 , a valve guide  230 , an elastic member  270 , a bypass valve  265 , a closing valve  260 , a piston support  250 , a main piston  220 , a rubber piston  215 , a half fluid  210 , a wax  205 , and a glow heater  200 . 
     In an upper end portion of the valve guide  230 , the main valve  240  is formed, and the main valve  240  blocks the radiator exhaust flow channel  126 . Further, in a lower end portion of the valve guide  230 , the closing valve  260  is formed, and the closing valve  260  blocks the engine exhaust flow channel  122 . 
     At one side of the main valve  240 , the bypass valve  265  is formed adjacent to the closing valve  260 . A distance between the closing valve  260  and the bypass valve  265  may be changed according to a design specification. 
     The elastic member  270  elastically supports the valve guide  230  upward to enable the main valve  240  to block the radiator exhaust flow channel  126  and enable the closing valve  260  to block the engine exhaust flow channel  122 . 
     Further, a driver that moves the valve guide  230  is formed with at least one of the wax case  207 , the glow heater  200 , the wax  205 , the half fluid  210 , the rubber piston  215 , the main piston  220 , and a piston guide  225 . 
     When a temperature of the wax  205  rises according to a temperature of the glow heater  200  or a peripheral coolant, the wax  205  expands to move the main piston  220  downward through the half fluid  210  and the rubber piston  215 . 
     When the main piston  220  moves downward, the main piston  220  presses downward the piston support  250  that is integrally formed with the valve guide  230 , and the valve guide  230  moves downward. 
       FIG. 4  is a cross-sectional view illustrating three operation states of a thermostat according to various embodiments of the present invention. In an initial operation state (e.g., lift=0 mm) in which the driver does not operate, the radiator exhaust flow channel  126  and the engine exhaust flow channel  122  are blocked by the main valve  240  and the closing valve  260 . 
     Here, a coolant circulates the engine  130 , the heater  120 , and the thermostat  100 . That is, a coolant circulates the engine  130 , the heater  120 , the heater exhaust flow channel  124 , and the engine inflow flow channel  128 . The heating line adjustment valve  150  is opened to operate the heater  120  according to a temperature of the coolant. 
     In an intermediate operation state (e.g., lift=5 mm) in which the driver operates in an intermediate level (e.g., 50%), the main valve  240  opens the radiator exhaust flow channel  126  by about 50%, and the closing valve  260  and the bypass valve  265  open the engine exhaust flow channel  122  by about 50%. 
     Here, a portion of the coolant circulates the engine  130 , the radiator  110 , the radiator exhaust flow channel  126 , the thermostat  100 , and the engine inflow flow channel  128 , and the remaining coolant circulates the engine  130 , the engine exhaust flow channel  122 , the engine inflow flow channel  128 , and the thermostat  100 . The heating line adjustment valve  150  is closed, and the heater  120  does not operate. 
     In a maximum operation state (e.g., lift=10 mm) in which the driver operates to the maximum (100%), the main valve  240  opens the radiator exhaust flow channel  126  by 100%, and the bypass valve  265  closes the engine exhaust flow channel  122 . 
     Here, the coolant circulates the engine  130 , the radiator  110 , the radiator exhaust flow channel  126 , the thermostat  100 , and the engine inflow flow channel  128 . Further, the heating line adjustment valve  150  is closed, and the heater  120  does not operate. 
     In various embodiments of the present invention, the radiator exhaust flow channel  126  is referred to as a first flow channel, the engine exhaust flow channel  122  is referred to as a second flow channel, the engine inflow flow channel  128  is referred to as a third flow channel, and the heater exhaust flow channel  124  is referred to as a fourth flow channel. 
     The thermostat  100  of the present invention may be applied to a coolant outlet that is disposed at a coolant outlet of the engine, and the thermostat  100  may be applied to a coolant inlet that is disposed at a coolant inlet of the engine. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper” or “lower”, “front” or “rear”, “upward” or “downward”, and etc. are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.