Claims:We Claim:
1. A coolant circulation system (100) for an engine (102), said system (100) located upstream to an engine (102) and comprising at least:
a pump (104) driven by said engine 102 and adapted to receive coolant from a radiator (106) via a first flow path (108) and deliver said received coolant to said engine through a second flow path (110), characterized in that:
a third flow path (112); and
a control valve (114) located along said third flow path (112),
said control valve (114) adapted to regulate flow of coolant through said third flow path (112) in dependence of the coolant temperature of said engine (102) measured at outlet of engine 102.

2. The coolant circulation system (100) of claim 1, wherein said third flow path 112 connects said first flow path 108 and said second flow path / coolant outlet 110.

3. A method for controlling flow of coolant in a coolant circulation system 100, said coolant circulation system 100 located upstream to an engine 102 and comprising at least:
a pump 104 adapted to receive coolant from a radiator 106 via a first flow path 108 and deliver said received coolant to said engine 102 through said second flow path/ coolant outlet 110, and a third flow path 112 comprising a control valve 114, said method comprising:
detecting (200), by a control unit a working temperature of coolant for a particular speed and load of the engine 102;
comparing (202) said working temperature of said coolant based on a data map with actual temperature for a said particular speed and load of said engine;
closing (204) said control valve 114 when said working temperature is more than said actual temperature; and
opening (206) said control valve 114 when said working temperature is less than said actual temperature.
, Description:Field of the invention
[0001] This invention relates to the field of coolant circulation system of an automotive internal combustion engine.

Background of the invention
[0002] A mechanical water pump that is used in an automobile engine is designed for highest cooling requirement (worst case conditions) and does not have provision to control the flow rate of coolant. This over cools the engine during warm up phase resulting in longer warm up time and higher CO2 emissions. Also since there is no control over coolant flow rate, coolant temperature control based on engine operating point, which is beneficial for CO2 reduction, is therefore not possible. Hence there is need for providing metered quantity of coolant to meet the cooling requirements of the engine based on the engine operating temperature.

Brief description of the accompanying drawing
[0003] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0004] FIG. 1 illustrates a coolant circulation system for an engine; and
[0005] FIG. 2 illustrates a method for controlling flow of coolant into the engine in coolant circulation system mentioned in FIG. 1.

Detailed description of the embodiments
[0006] FIG. 1 illustrates a coolant circulation system for an engine 102. The system 100 is located upstream to an engine 102 and comprises a pump 104 driven by the engine and is adapted to receive coolant from a radiator 106 via a first flow path 108 and deliver the received coolant to the engine 102 through the second flow path 110. The system 100 comprises a third flow path 112, and a control valve 114 located along the third flow path 112. The control valve 114 is adapted to regulate flow of coolant through the third flow path 112, in dependence of the coolant temperature of the engine 102 measured at the outlet of the engine. The third flow path 112 is in flow communication with the first flow path 108 and the second flow path 110. The Coolant circulation system 100 comprises a temperature sensor 109 located at outlet of engine 102 for measuring temperature of coolant at outlet of engine 102, the temperature sensor 109 is in communication with the control unit 111.

[0007] The working of the coolant circulation system 100 will be explained in further detail. When the engine 102 is cranked/ started, the coolant circulation system 100 is switched on. A control unit 111 receives the working temperature of coolant at outlet of engine 102 from temperature sensor 109. The term working temperature denotes the temperature of the coolant during normal working of the engine as measured by the temperature sensor 109. The control unit then compares this input temperature with the temperature of coolant obtained from data map and controls the control valve 114 accordingly. If the working temperature of the coolant, as measured by temperature sensor 109, is less than the temperature of the coolant obtained from data map and as calculated by the control unit, then the control valve 114 is opened and coolant flows through the flow path 112. If the actual temperature of the coolant, as measured by temperature sensor 109, is more than the target temperature of the coolant, as determined by the control unit, then the control valve 114 closes, which reduces the flow through the flow path 112, thus increasing the coolant flow through the engine 102. This in turn reduces the coolant temperature inside the engine and the same is measured by temperature sensor 109. This process is continuous. The control unit 111 takes the feedback signal from temperature sensor 109 and regulates the control valve 112 continuously. Thus the coolant flow through the engine 102 is controlled continuously and also the coolant temperature is thus controlled independent of engine speed and load and thermostat setting.
[0008] During cold phase of the engine, the target temperature set by control unit is higher than actual temperature as measured by temperature sensor 109 because the engine should warm up in a short span of time. In this case the control valve 114 is opened completely. Thus coolant flow through the engine 102 will be minimum aiding the faster warm up.
[0009] FIG. 2 illustrates a method for controlling flow of coolant in a coolant circulation system 100. The coolant circulation system 100 is located upstream to an engine 102 and comprises at least, a pump 104 adapted to receive coolant from a radiator 106 via a first flow path 108 and deliver the received coolant to the engine 102 through a second flow path or pump outlet 110, and a third flow path 112 comprising a control valve 114. The method comprises, detecting (200) by a control unit the working coolant temperature for a particular load and speed of the engine 102. Comparing (202) the working temperature of the coolant based on data map fed into the control unit, with the actual temperature of engine, opening (204) the control valve 114 when the working temperature is less than the actual temperature and closing (206) the control valve 114 when the working temperature is greater than the actual temperature.
[0010] During warm up phase of engine 102 from cold condition, cooling requirements are relatively lower and only a small amount coolant flow is required to avoid overheating of engine 102 components. In this case the control valve 114 and thus the third flow path 112 is open, which is controlled by the control unit, and coolant flows back to the inlet of the pump 104 based on control valve 114 opening. Thus only a metered amount of coolant flows through the engine 102, warming up the engine 102 faster. Also during the normal engine 102 operation, the control valve 114 could be adjusted such that only metered quantity of coolant flows through the engine 102. Thus it is possible to maintain coolant temperature independent of engine 102 speed and load. The control valve could be a normally closed pneumatic / electric progressive valve. Thus by using a normally closed progressive control valve 114, safety of the engine 102 can be ensured.
[0011] The proposed system 100 enables faster engine 102 warm up reducing cold phase emissions and better cold phase fuel economy. Also, the engine operating based coolant temperature control enables coolant temperature to go up to as high as 100 degree Celsius at lower part load increasing the oil temperature thus reducing the friction, CO2 emission. At higher engine 102 loads coolant temperature is reduced to keep the oil temperature under control, thus to allow the engine 102 to operate under safe conditions. This helps in reducing CO2 emission of a vehicle.
[0012] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention in terms of type of. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.