Patent Publication Number: US-2010122670-A1

Title: Fluid circuit of engine

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application No. 10-2008-0114793 filed on Nov. 18, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an engine. More particularly, the present invention relates to a fluid circuit of an engine that includes a cooling circuit and an oil circuit. 
     2. Description of Related Art 
     Generally, subsidiary units are mounted on an engine. Here, the subsidiary units are devices that assist the operation of the engine. 
     Sometimes devices for improving the output of the engine are mounted thereon. For example, a turbocharger can be installed so as to turbocharge air into the engine. The turbocharger uses exhaust pressure that is formed during the exhaust stroke of the engine to rotate a turbine so as to turbocharge the air into an intake manifold. 
     Also, a continuously variable valve timing (CVVT) device is disposed in the engine to vary the operation timing of a valve so as to improve intake efficiency and exhaust efficiency. 
     When the number of constituent elements that are mounted on the engine as stated above is increased, it is important that related cooling and oil circuits are provided. In addition to durability and performance of each component, the circuits can affect the overall performance of the engine. 
     The information disclosed in this Background of the Invention 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. 
     BRIEF SUMMARY OF THE INVENTION 
     Various aspects of the present invention are directed to provide a fluid circuit of an engine in which an oil circuit and a cooling circuit that are disposed between an engine and a subsidiary unit is improved such that each circuit becomes simple without a flux decrease thereof. 
     A fluid circuit of an engine that is fitted with a cooling circuit and an oil circuit, may include a water pump that is mounted on a coolant circulation line, a radiator that is connected to a coolant exhaust line of the engine, a water temperature governor that selectively connects the radiator with the water pump to control a coolant flow therebetween, a first cooling line that connects the coolant exhaust line with a subsidiary unit, a first return line that directly connects the subsidiary unit with the water pump through the water temperature governor, a second cooling line that connects the first cooling line to a turbocharger to guide a part of a coolant that is supplied to the first cooling line to the turbocharger, and a second return line that connects the turbocharger with the first return line to guide a coolant that is exhausted from the turbocharger to the first return line. 
     The water temperature governor may include a main line that connects the radiator and water pump and selectively supplies a coolant that is transmitted from the radiator to the water pump, and a bypass line that is separately formed from the main line and directly connects the first return line to the water pump to guide a coolant that is returned from the first return line to the water pump, wherein a main valve that is mounted in the main line and is opened or closed according to a temperature of the coolant that is transmitted from the radiator to control the coolant flow between the radiator and the water pump. 
     The main line and the bypass lien may be integrally formed in the water temperature governor. 
     In a case that the temperature of the coolant transmitted from the radiator is higher than a predetermined temperature, the main valve may be opened such that the coolant that is cooled through the radiator is supplied to the water pump. 
     The bypass line may be a non-bypass valve type through which the coolant always flows. 
     The oil circuit may include a main oil line that is mounted in a cylinder block of the engine to receive oil from a hydraulic pump, a first oil line that connects the turbocharger with the main oil line to guide the oil that is supplied from the main oil line to the turbocharger, and a second oil line that guides oil that is returned from the turbocharger to the main oil line. 
     In various aspects of the present invention, the fluid circuit of the engine may be formed such that the water temperature governor is operated according to the coolant temperature that flows in the water temperature governor from the radiator. Further, the coolant that flows to the water temperature governor from the subsidiary units may be directly returned to the water pump such that the cooling circuit becomes simple without a flux decrease of the coolant. 
     Also, the coolant may be circulated through the cooling circuit that is connected to the turbocharger at all times such that the oil circuit that is connected to the turbocharger sustains the oil temperature thereof around the cooling circuit of the turbocharger. 
     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 of the Invention, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing a fluid circuit of an engine according to an exemplary embodiment of the present invention. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION OF THE INVENTION 
     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 diagram showing a fluid circuit of an engine according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , the fluid circuit of an engine  20  according to an exemplary embodiment of the present invention includes a cooling circuit and an oil circuit that are disposed around the engine. 
     Firstly, the cooling circuit includes a water pump  10 , an engine  20 , a radiator  30 , a water temperature governor  40 , a first cooling line  50 , a first return line  60 , a second cooling line  70 , and a second return line  80 . 
     In the cooling circuit according to an exemplary embodiment of the present invention, the cooling circuit that is related to the embodiment regarding the engine  20  and the peripheral constituents thereof shown in  FIG. 1  is detailed, and it is not limited thereto. 
     The water pump  10  is disposed on a coolant circulation line to be operated by the engine such that the coolant is circulated through the coolant circulation line. 
     A water jacket is formed inside the engine  20 , the coolant that is supplied from the water pump  10  passes through the water jacket, and a coolant exhaust line  22  and a coolant inflow line are also formed therein. 
     The radiator  30  is connected to the coolant exhaust line  22  of the engine  20 . 
     The water temperature governor  40  is mounted between the radiator  30  and the water pump  10  to control the coolant flow. A main line  42  and a bypass line  44  are formed inside the water temperature governor  40 . 
     The main line  42  guides the coolant that is supplied from the radiator to the water pump  10 . A main valve  46  is mounted on the main line  42  to be opened/closed according to the coolant temperature that is supplied from the radiator  30 . 
     The bypass line  44  is separately formed from the main line  42  to guide the coolant that is returned from the first return line  60  to the water pump  10 . The bypass line  44  can be connected to one side of the main line  42 . 
     The bypass line  44  may be a no-bypass type through which the coolant is always flowing. 
     The first cooling line  50  connects the coolant exhaust line  22  and a subsidiary unit  90 . 
     The first return line  60  connects the subsidiary units  90  with the water temperature governor  40  to guide the coolant that cools the subsidiary unit  90  to the water temperature governor  40 . 
     The second cooling line  70  connects the first cooling line  50  with a turbocharger  100  to guide the part of the coolant that is supplied from the first cooling line  50  to the turbocharger  100 . 
     The turbocharger  100  includes a turbocharger intercooler. The turbocharger intercooler represents a device in which an intercooler is added to a turbocharger. 
     During the operation of the engine  20 , an exhaust turbine of the turbocharger  100  is rotated by exhaust flow energy of the exhaust gas that is exhausted from an exhaust manifold of the engine  20 . 
     The exhaust turbine is directly connected to the compressor, and the compressor rotates with the exhaust turbine. The compressor rotates to turbocharge the air into the intake manifold through an air cleaner. 
     The compressed air is cooled by the intercooler to be supplied into the intake manifold. Accordingly, the engine  20  to which the turbocharger  100  is fitted can use a larger amount of air than a general engine. 
     The coolant is supplied to the turbocharger  100  through the second cooling line  70 , and the turbocharger  100  is affected by the temperature of the coolant. The coolant that passes through the turbocharger  100  is returned to the water temperature governor  40  through the second return line  80 . 
     The second return line  80  connects the turbocharger  100  with the first return line  60  to guide the coolant that is exhausted from the turbocharger  100  to the first return line  60 . 
     Further, the oil circuit includes a main oil line, a first oil line  102 , and a second oil line  104 . 
     The oil circuit according to an exemplary embodiment of the present invention can be applied to an engine having a continuously variable valve timing (CVVT) device. The main oil line holds the oil circuit of the continuously variable valve timing apparatus in common. If necessary, the turbocharger oil circuit can be independently formed with the oil circuit of the continuously variable valve timing apparatus. 
     The main oil line is formed inside the engine  20  to receive the oil from a hydraulic pump. 
     The first oil line  102  connects the main oil line with the turbocharger  100  to guide the oil to the turbocharger  100 . 
     The second oil line  104  guides the oil that is returned to the main oil line. 
     The coolant is circulated through the cooling circuit that is connected to the turbocharger  100  at all times according to an exemplary embodiment of the present invention, such that the oil circuit that is connected to the engine  20  and to the turbocharger  100  is always cooled to sustain an appropriate temperature thereof by the cooling circuit. 
     The oil circuit according to an exemplary embodiment of the present invention relates to the relationship of the engine  20  and the turbocharger  100  and other oil circuits that can be formed in other parts of the engine  20 , but is not limited thereto. 
     Referring to  FIG. 1 , the fluid circuit of the engine is detailed according to an exemplary embodiment of the present invention. 
     When the engine  20  is started, the coolant for cooling the engine  20  is heated by combustion heat that is generated during the operation of the engine  20 . Before the engine  20  is warmed up, the temperature of the coolant is relatively low, and so the coolant circulates in the water jacket within the engine. 
     The water pump  10  is disposed on one side of the engine  20 . 
     The water pump  10  circulates the coolant so as to cool the engine  20 . The coolant that is supplied from the water pump  10  to pass through the engine  20  flows into the radiator  30  to be cooled. 
     In this condition, the engine  20  is completely warmed up, that is, the coolant temperature is higher than a predetermined temperature, and the main valve  46  that is mounted inside the water temperature governor  40  is opened such that the coolant that is cooled through the radiator  30  is supplied to the water pump  10 . 
     However, the coolant that is supplied to the subsidiary unit  90  through the first cooling line  50  cools the subsidiary unit  90 . The coolant that cools the subsidiary unit  90  is returned to the bypass line  44  of the water temperature governor  40  through the first return line  60 . The coolant that reaches the bypass line  44  of the water temperature governor  40  is supplied to the water pump  10  through the main line  42  and the bypass line  44  thereof. 
     The first cooling line  50  is connected to the second cooling line  70 . Accordingly, the part of the coolant that is supplied to the subsidiary unit  90  through the first cooling line  50  is supplied to the turbocharger  100  through the second cooling line  70 . 
     The coolant that cools the turbocharger  100  flows to the first return line  60  through the second return line  80  to be returned to the bypass line  44  of the water temperature governor  40 . 
     Likewise, the coolant cooling the subsidiary unit  90  and the coolant cooling the turbocharger  100  is supplied to the water pump  10  of the water temperature governor  40  through the bypass line  44  and the main line  42 . 
     Here, if the coolant that is supplied to the subsidiary unit  90  and the turbocharger  100  is retuned to the water temperature governor  40 , the flow thereof is not controlled regardless of the coolant temperature. 
     That is, the coolant that flows to the water temperature governor  40  through the radiator  30  guides the main valve  46  to control the coolant flowing according to the coolant temperature. 
     Differing from this, the coolant that is supplied to other than the radiator  30  to return to the water temperature governor  40  is directly supplied to the water pump  10  regardless of the coolant temperature such that the coolant flow thereof is not controlled. 
     That is, the water temperature governor  40  is operated to be opened or closed according to the temperature of the coolant that flows from the radiator  30  to the water temperature governor  40 , and the coolant circuit is configured such that the coolant that flows from the subsidiary unit  90  to the water temperature governor  40  flows directly to the water pump  10 . 
     An inlet control method is applied to the cooling circuit according to an exemplary embodiment of the present invention. 
     For reference, in the inlet control method, the coolant of the radiator  30  is controlled to flow to the engine  20  according to the temperature of the engine  20 . 
     That is, if the coolant temperature that flows from the radiator  20  to the coolant inlet of the engine  20  is higher than a predetermined temperature, the main valve  46  of the water temperature governor  40  is opened such that the coolant of the radiator  30  flows to the water temperature governor  40 . 
     The coolant that flows to the water temperature governor  40  is mixed with the coolant that passes the subsidiary unit  90  and the turbocharger  100  to be supplied to the water pump  10 . 
     The water temperature governor  40  according to an exemplary embodiment of the present invention is controlled in the inlet control method, but the coolant flowing in the bypass line  44  is not controlled. A separate bypass valve is not disposed on the bypass line  44 , that is, there is no bypass valve thereon to improve the operability of the water temperature governor  40 . 
     The coolant flux of the radiator  30  is controlled according to the coolant temperature that is returned to the inlet of the engine, but the coolant flux that circulates in the subsidiary unit  90  and the turbocharger  100  is not controlled regardless of the coolant temperature thereof. 
     As described above, the cooling line for the subsidiary units  90  and the turbocharger  100  are simultaneously configured in the bypass line  44  such that the coolant is securely supplied thereto regardless of the operation condition of the engine, so the cooling circuit becomes simple. 
     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.