FIELD OF INVENTION

The present invention generally relates to a system and a method for cooling an engine and more specifically the present invention relates to a cooling system and a method of cooling an engine of a vehicle.

BACKGROUND OF INVENTION

In a conventional cooling system of a vehicle, radiators (Heat exchangers) are used to remove the excess thermal energy in many automotive applications and, as such, the efficiency is very important for the vehicles. Since packaging is the biggest constraint in the automobiles hence radiators are used because of their minimum space requirements and high heat removal capabilities. The circulation of coolant through the radiator is governed by the thermostat, which maintains the temperature of the engine at optimum level where it gives best thermal efficiency. Also the air after turbocharger needs to be moved through Charge Air Cooler (CAC) to take out the heat from the air, before it enters the combustion chamber thereby improving the volumetric efficiency of the engine.

The conventional cooling system has double stack cooling package with viscous fan. These products have the double stack arrangement of the Radiator and CAC i.e. Radiator and CAC are mounted one behind the other. The CAC is mounted in front of the radiator.

The size of each of the component can be worked out depending on the heat to be removed from the system, which is calculated for the worst-case criteria. The viscous fan diameter is decided based on the airflow required to meet the cooling requirement. The viscous fan has a high viscosity silicone fluid inside the fan clutch and a bimetallic strip.
This bimetallic strip opens up based on the temperature of the air coming out of radiator and the opening of bimetallic strip is responsible for engagement and disengagement of the fan.

The vehicle cooling system plays a pivotal role in efficient running of the engine and the cooling system efficiency is determined by the system restriction across the radiator and CAC (Charge Air Cooler) assembly. The heat exchanger can be improved if it delivers more heat flow for same pressure drop and / or if it delivers same heat flow for less pressure drop and / or if heat exchanger is smaller and still delivers same heat flow for same pressure drop.

In the conventional cooling system, the atmospheric air (at atmospheric temperature) passes through the CAC and takes out the heat from the boost air i.e. air after turbocharger. The atmospheric air at elevated temperature, after passing through CAC, then passes through radiator and further cools down the coolant flowing through the radiator. The air then again gains temperature after passing through the radiator. The bimetallic coil mounted in front of the fan clutch senses this air temperature and based on this temperature the fan is engaged or disengaged.

When the engine operating temperature is below a predetermined set temperature, the thermostat is kept closed and no coolant flows through the radiator. Hence we don't require any cooling in that condition so fan is in disengaged mode. And when the engine operating temperature starts increasing beyond 80°C the thermostat starts opening and coolant starts flowing through the radiator partially. At 90°C the thermostat is in fully open condition and the full coolant is flowing through the radiator. As the engine operating temperature increases, the temperature of the atmospheric air coming from the radiator also starts increasing which leads to the fan engagement as the temperature reaches the set engagement temperature of the clutch.

The cooling of the boost air, coming from turbocharger, is done to reduce the temperature of the air entering into the combustion chamber. We need cooler air in the combustion chamber so as to ensure complete combustion of the fuel, which helps in more power generation and lesser emissions.

The present invention meets the challenge which lies in proposing a cooling package for future vehicles, which complies with the requirement of automotive vehicles. It meets the greater challenge as the heat load increases with the use of following:

1. EGR (Exhaust Gas Re-circulation) - Exhaust Gas Re-circulation to meet the BS IV (Bharat Stage) emission norms and beyond

2. Heating, ventilation and Air-conditioning for the cabin

3. Transmission Oil Cooler - Automatic transmission, manual transmission in heavy-duty application.

And to dissipate the high value of heat load we have to use a technology, which can help us, track all the temperatures and provide the airflow as per demand.

One of the related arts discloses a high low temperature water cooling system which is formed of a high temperature cooling water circulation system and a low temperature cooling water circulation system which are formed through the high temperature heat exchanger and low temperature heat exchanger so that the high temperature cooling water heated by the engine is heat exchanged with an external air in the high temperature heat exchanger and then is used for cooling the engine. A part of the cooling water cooled by the high temperature heat exchanger is re-cooled using the low temperature heat exchanger for thereby cooling the charged air and transmission oil which circulate in the CAC and oil cooler. Thus, a combination of heat exchanging method is adopted.

However, all these arts have drawbacks relating to cooling the engine in an efficient manner particularly in cooling and maintaining the radiator and the CAC such that they can be maintained at different temperatures and thereby engine efficiency can be improved. This is due to the fact that all these arts discloses cooling system wherein the radiator and the CAC are treated as single entity and accordingly the cooling system is being formulated. Whereas if the radiator and the CAC are discriminated as different entity and cooling system if devised accordingly, the engine efficiency will be improved by maintaining the engine temperature at a desired temperature and by providing the air from the CAC at a desired temperature irrespective of the external conditions the engine is placed whether in cold or in hot environment. Thus the engine atmospheric conditions also can be taken into consideration and accordingly the radiator and the CAC can be cooled.

Thus there arises a need to provide a cooling system for cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in the radiator and in the CAC and there arises a need to provide a method for cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in the radiator and in the CAC.

OBJECT OF INVENTION

One object of invention relating to the present invention is to provide a cooling system for cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in radiator and in CAC of a vehicle.

Another object of invention relating to the present invention is to provide a method of cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in radiator and in CAC of a vehicle.

SUMMARY OF INVENTION

According to one aspect of the present invention a cooling system for cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in radiator and in CAC of a vehicle is provided which comprises a radiator having one or more inlet and one or more outlet preferably having one inlet and one outlet, the inlet of the radiator is connected to a coolant outlet path from the engine through a thermostat and the outlet of the radiator is connected to a coolant inlet path to the engine. A CAC having one or more inlet and one or more outlet preferably having one inlet and one outlet which is placed underneath the radiator and is physically independent from the radiator, the inlet of the CAC is connected to air outlet of a turbocharger and the outlet of the CAC is connected to air inlet path to the engine through an intake manifold. Two separate fans are used for radiator and CAC which are first fan and second fan respectively. The first fan is mechanically connected to the engine and is placed aside the radiator preferably behind any one of the sides of the radiator. The first fan is preferably a pull type fan and is capable of being controlled by an Engine Control Unit (ECU). The ECU is electrically connected to the first fan and to a first sensor which is present inside the thermostat. A second fan is mechanically placed aside the CAC preferable in front of any one of the surfaces of the CAC. The second fan is preferably a pull type or push type fan. The second fan is capable of being controlled by a second fan controller means which is electrically connected between the second fan, a second sensor and the ECU wherein the first fan and the second fan can be controlled independently by the ECU such that the temperature of the radiator and the CAC can be maintained as desired which is independent from each other.

According to another aspect of the present invention a method of cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in radiator and in CAC of a vehicle is provided which comprises the steps of sensing the temperature of the engine coolant by a first sensor present in thermostat and by a second sensor present in between turbocharger and CAC. The method comprises the steps of controlling a first fan speed placed aside the radiator preferably behind any one of the sides of the radiator by ECU The method comprises the steps of controlling a second fan speed placed aside the CAC preferable in front of any one of the surfaces of the CAC by the ECU. The method comprises the steps of allowing heated coolant to pass from the engine to the radiator when the engine coolant temperature reaches beyond 80°C. The method comprises the steps of allowing boost air to pass from the turbocharger to the CAC and controlling the temperature in the radiator and in the CAC independently from each other by the ECU based on their respective temperatures.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a cooling system for cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in radiator and in CAC of a vehicle in accordance with an exemplary embodiment of the present invention; and

FIG. 2 illustrates a method for cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in radiator and in CAC of a vehicle in accordance with another exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF DRAWINGS

Referring to FIG. 1 a cooling system for cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in radiator and in CAC in accordance with an exemplary embodiment of the present invention is illustrated.
A cooling system (100) for cooling an engine (109) of a vehicle comprises a radiator (106) having one or more inlet and one or more outlet preferably having one inlet and one outlet, the inlet of the radiator is connected to a coolant outlet path (113) from the engine through a thermostat (101) and the outlet of the radiator is connected to a coolant inlet path (116) to the engine. A CAC (107) having one or more inlet and one or more outlet preferably having one inlet and one outlet, which is placed underneath the radiator and is physically independent from the radiator, the inlet of the CAC is connected to air outlet path (114) from turbocharger (102) through a second sensor (118) and the outlet of the CAC is connected to air inlet path (115) to the engine through an intake manifold (103). A first fan (104) mechanically placed aside the radiator preferably behind any one of the sides of the radiator and the first fan is capable of being controlled by an ECU (112) which is electrically connected between the first fan and a first sensor which is present inside the thermostat. A second fan (108) mechanically placed aside the CAC preferable in front of any one of the surfaces of the CAC and the second fan is capable of being controlled by a second fan controller means (111) which is electrically connected between the second fan and a second sensor (118) and the ECU wherein the first fan and the second fan can be controlled independently by the ECU such that the temperature of the radiator and the CAC can be maintained as desired which is independent from each other.

The first fan of the cooling system has a solenoid (105) which is capable of being magnetized when a calibrated value of current is passed through it.

The ECU of the cooling system is capable of reading the coolant temperature flowing towards the radiator through the first sensor present in thermostat and rotates the first fan at a desired speed by controlling the voltage fed across the first fan such that the rotation speed of the first fan maintains a desired temperature of the coolant coming out of radiator.

The ECU of the cooling system is capable of reading the air temperature flowing towards the CAC through the second sensor (118) present between turbocharger and CAC and rotates the second fan at a desired speed by controlling the voltage fed across the second fan through the second fan controller means such that the rotation speed of the second fan maintains a desired temperature of the air coming out of CAC.

The first fan rotation of the cooling system can be controlled by the ECU by varying the voltage across the first fan. The second fan of the cooling system rotation can be controlled by the ECU by varying the voltage across the second fan.

The coolant paths (113, 116) and the air paths (114, 115) of the cooling system are in tubular pipes and the coolant is a mixture of ethylene glycol and water in the ratio 50:50.

The thermostat of the cooling system opens when the engine temperature reaches beyond 80°C and allows the hot coolant to flow out of the engine and into the radiator. In the present invention, the heat is removed by circulating the coolant, which is 50:50 ratio of water and Ethylene glycol, through the engine and radiator.

The first fan of the cooling system is fixed on to the surface of the engine such that the blowing face of the first fan fully impinges the surface of the radiator. The second fan of the cooling system is fixed on to the surface of the CAC such that the blowing face of the second fan fully impinges the surface of the CAC. Preferable the first fan faces the larger surface area of the radiator and preferable the second fan faces the larger surface area of the CAC.

The first fan of the cooling system has a solenoid that opens and closes the working port of the viscous clutch to engage and disengage the fan respectively. The first fan of the cooling system is activated by the ECU in accordance with the temperature sensed by the first sensor (117) present in the thermostat The second fan of the cooling system is activated by the ECU through the second fan controller means (111) in accordance with the temperature sensed by the second sensor (118) present between the turbocharger and the CAC.

The ECU of the cooling system is capable of reading the temperature of the engine through the first sensor present inside the thermostat.

The present invention enhances the performance of the cooling system as a whole, by providing an individual fan for Radiator and CAC as there may be a condition where from the coolant temperature sensor we don't need any cooling but from CAC temperature sensor we need the fan to rotate at certain desired rpm. Also the CAC fan has to be continuously rotating one but with different heat loads which depends on the operating condition of the vehicle. By providing the individual fans, we can better control the temperatures of the coolant and boost air to get the best performance from the engine.

This in turn helps in saving fuel, which was earlier used to run the fan at higher rpm's (revolution per minute), and using this whole system as a package we are reducing the frictional horsepower of the vehicle. Thus, increasing the brake horsepower of the vehicle and hence increasing the KMPL (Kilometer per liter) of the vehicle.

In the proposed invention, the radiator and CAC have been mounted in single stack i.e. CAC is mounted below the radiator. The electronic-viscous fan has been used for cooling radiator alone and a small electrical fan has been used to cool the air passing through CAC.

In Single stack arrangement, the atmospheric air simultaneously passes through the radiator and CAC at atmospheric temperature. This leads to the lower pressure drop of outer air across the individual component and better efficiency of the components viz. radiator and CAC. The electronic viscous fan adjusts itself to different temperature conditions of the coolant and gives the airflow, which is sufficient enough to provide the cooling of coolant. Under this, the ECU gives the voltage signal to fan controller to run at a required rpm. Here, a sensor measures the coolant temperature and we want our engine to run at a temperature band where it gives the best thermal efficiency. From above explanation, it calculates the heat to be dissipated, and the airflow required to dissipate the calculated amount of heat. From the airflow requirement value, we calculate the fan rpm at which fan has to rotate. This requirement is converted into voltage signal and fed to fan controller to get the required fan rpm. Similarly, an electrical fan is used for CAC alone where logic has been built for varying the rpm of fan based on the temperature of the air coming after the turbocharger. Thus the power consumption by the system as a whole is substantially reduced.

The process of using an electronic-viscous fan for radiator results in reducing the fan duty cycle i.e. the percentage of time the fan is in engaged condition which in turn lead to the fuel efficiency improvement of the vehicle as the power which was earlier consumed by fan is now available for doing the useful work.

The present invention deals with BS III and BS IV and beyond vehicles which uses electronics for engines and to leverage the benefit of electronics in the system and the data like coolant outlet temperature, transmission oil temperature, cabin temperature etc, can be captured from the ECU and utilized for further enhancement. Based on the above-mentioned inputs, the fan is run at required rpm as per the heat load.

Referring to FIG. 2 a method for cooling coolant and boost air of an engine independently and to maintain a desired temperature independently in radiator and in CAC of a vehicle in accordance with another exemplary embodiment of the present invention is illustrated.

A method of cooling an engine for a vehicle the method comprises the steps of sensing the temperature of a coolant flowing to a radiator by a first sensor present in thermostat.

Also, sensing the temperature of air flowing to a CAC by a second sensor present in second fan controller means. Controlling a first fan speed placed aside the radiator by an ECU based on the temperature sensed by the first sensor. Controlling a second fan speed placed aside the CAC by the engine control unit based on the temperature sensed by the second sensor. Allowing heated coolant to pass from the engine to the radiator when the engine temperature reaches beyond a desired temperature. Allowing hot air to pass from the engine to the CAC and controlling the temperature of the coolant coming out of the radiator and the air coming out of the CAC independently from each other by the engine control unit based on their respective temperatures.

The method comprises the step wherein the ECU reads the coolant temperature through the first sensor.

The method comprises the step wherein the ECU reads the air temperature through the second fan controller means;

The method comprises the step wherein upon the engine temperature reaches beyond 80°C, the thermostat opens and the ECU activates the first fan and controls the voltage such that the first fan rotates at a speed to attain desired temperature of the coolant coming out of the radiator.

The method comprises the step wherein upon the engine becomes hot, the ECU activates the second fan and controls the voltage such that the second fan rotates at a speed to attain desired temperature of the air coming out of the CAC.

The method comprises the step wherein upon the engine becomes hot, the hot coolant flows from the engine to the radiator which reduces the temperature of the coolant and sends the less temperature coolant back to the engine again.

The method comprises the step wherein upon the engine becomes hot, the hot air flows from the turbocharger of the engine to the CAC which reduces the temperature of the air and sends the less temperature air back to the engine again through the intake manifold.

The method comprises the step wherein the ECU activates the first fan to cool the radiator and the second fan to activate the CAC such that both are activated independently and independent desired temperature are maintained in the coolant and in the air in radiator and CAC respectively.

The method comprises the step wherein when the ECU increases the voltage across the first fan, the first fan speed increases and when the ECU decreases the voltage across the first fan, the first fan speed decreases.

The method comprises the step wherein when the ECU increases the voltage across the second fan, the second fan speed increases and when the ECU decreases the voltage across the second fan, the second fan speed decreases

We Claim:

1. A cooling system (100) for cooling an engine (109) of a vehicle, the cooling
system comprising:

a radiator (106) having one or more inlet and one or more outlet, the inlet of the radiator is connected to a coolant outlet path (113) from the engine through a thermostat (101) and the outlet of the radiator is connected to a coolant inlet path (116) to the engine;

a charge air cooler (107) having one or more inlet and one or more outlet which is placed underneath the radiator and is physically independent from the radiator, the inlet of the charge air cooler is connected to air outlet path (114) from a turbocharger (102) through a second sensor (118) and the outlet of the charge air cooler is connected to air inlet path (115) to the engine through an intake manifold (103);

a first fan (104) mechanically placed aside the radiator and the first fan is capable of being controlled by an engine control unit (112) which is electrically connected between the first fan and a first sensor (117) which is present inside the thermostat;

a second fan (108) mechanically placed aside the charge air cooler and the second fan is capable of being controlled by a second fan controller means (111) which is electrically connected between the second fan and a second sensor (118) and the engine control unit wherein the first fan and the second fan can be controlled independently by the engine control unit such that the temperature of the radiator and the charge air cooler can be maintained as desired which is independent from each other.

2. The cooling system as claimed in claim 1 wherein the first fan has a solenoid (105) which is capable of being magnetized when a current is passed through it.

3. The cooling system as claimed in any one of the preceding claims wherein the engine control unit is capable of reading the coolant temperature flowing towards the radiator through the first sensor present in the thermostat and rotates the first fan at a desired speed by controlling the voltage fed across the first fan such that the rotation speed of the first fan maintains a desired temperature of the coolant coming out of radiator.

4. The cooling system as claimed in any one of the preceding claims wherein the engine control unit is capable of reading the air temperature of the charge air cooler through the second fan controller means and rotates the second fan at a desired speed by controlling the voltage fed across the second fan through the second fan controller means such that the rotation speed of the second fan maintains a desired temperature of the air coming out of the charge air cooler.

5. The cooling system as claimed in any one of the preceding claims wherein the first fan rotation can be controlled by the engine control unit by varying the voltage across the first fan.

6. The cooling system as claimed in any one of the preceding claims wherein the second fan rotation can be controlled by the engine control unit by varying the voltage across the second fan.

7. The cooling system as claimed in any one of the preceding claims wherein the coolant paths (113,116) and the air paths (114,115) are in tubular pipes.

8. The cooling system as claimed in any one of the preceding claims wherein the coolant is a mixture of ethylene glycol and water in the ratio 50:50.

9. The cooling system as claimed in any one of the preceding claims wherein the thermostat opens when the engine temperature reaches beyond 80°C and allows the hot coolant to flow out of the engine and into the radiator.

10. The cooling system as claimed in claim 1 wherein the first fan is fixed on to the surface of the engine such that the blowing face of the first fan fully impinges the surface of the radiator.

11. The cooling system as claimed in claim 1 wherein the second fan is fixed on to the surface of the charge air cooler such that the blowing face of the second fan fully impinges the surface of the charge air cooler.

12. The cooling system as claimed in claim 1 wherein the first sensor is capable of sensing the temperature of the engine and the coolant and accordingly enables the engine control unit to control the solenoid (105) such that the solenoid opens and closes the working port of the clutch to engage and disengage the first fan.

13. The cooling system as claimed in claim 1 wherein the second fan controller means is adopted with a second sensor (118) which is capable of sensing the air temperature from the turbocharger and accordingly enables the second fan controller means to control the speed of the second fan through the engine control unit.

14. A method of cooling an engine for a vehicle the method comprises the steps of:

sensing the temperature of a coolant flowing to a radiator by a first sensor present in thermostat;

sensing the temperature of air flowing to a charger air cooler by a second sensor present in second fan controller means;

controlling a first fan speed placed aside the radiator by an engine control unit based on the temperature sensed by the first sensor;

controlling a second fan speed placed aside the charge air cooler by the engine control unit based on the temperature sensed by the second sensor;

allowing heated coolant to pass from the engine to the radiator when the engine temperature reaches beyond a desired temperature;

allowing hot air to pass from the engine to the charge air cooler; and

controlling the temperature of the coolant coming out of the radiator and the air coming out of the charge air cooler independently from each other by the engine control unit based on their respective temperatures.

15. The method as claimed in claim 14 wherein the engine control unit reads the
coolant temperature through the first sensor;

16. The method as claimed in claim 14 wherein the engine control unit reads the air temperature through the second fan controller means;

17. The method as claimed in any one of the preceding claims 14 to 16 wherein upon the engine temperature reaches beyond 80°C, the thermostat opens and the engine control unit activates the first fan and controls the voltage such that the first fan rotates at a speed to attain desired temperature of the coolant coming out of the radiator.

18. The method as claimed in any one of the preceding claims 14 to 17 wherein upon the engine becomes hot, the engine control unit activates the second fan and controls the voltage such that the second fan rotates at a speed to attain desired temperature of the air coming out of the charge air cooler.

19. The method as claimed in any one of the preceding claims 14 to 18 wherein upon the engine becomes hot, the hot coolant flows from the engine to the radiator which reduces the temperature of the coolant and sends the less temperature coolant back to the engine again.

20. The method as claimed in any one of the preceding claims 14 to 19 wherein upon the engine becomes hot, the hot air flows from the turbocharger of the engine to the charge air cooler which reduces the temperature of the air and sends the less temperature air back to the engine again through the intake manifold.

21. The method as claimed in any one of the preceding claims 14 to 20 wherein the engine control unit activates the first fan to cool the radiator and the second fan to activate the charge air cooler such that both are activated independently and independent desired temperature are maintained in the coolant and in the air in radiator and charge air cooler respectively.

22. The method as claimed in any one of the preceding claims 14 to 21 wherein when the engine control unit increases the voltage across the first fan, the first fan speed increases and when the engine control unit decreases the voltage across the first fan, the first fan speed decreases.

23. The method as claimed in any one of the preceding claims 14 to 22 wherein when the engine control unit increases the voltage across the second fan, the second fan speed increases and when the engine control unit decreases the voltage across the second fan, the second fan speed decreases.