CLIAMS:I Claim:

1. A method to determine a state of Diesel Exhaust Fluid (DEF) in a DEF tank of a vehicle, said method comprising

determining a DEF level in said DEF tank;

detecting a sloshing phenomenon of said DEF based on said determined DEF level; and

determining said state of said DEF based on said detected sloshing phenomenon.

2. A device 100 to determine a state of Diesel Exhaust Fluid (DEF) in a DEF tank of a vehicle, said device 100 comprising

a DEF level sensor 101 to determine a DEF level in said DEF tank;

a sloshing detection means 102 to detect a sloshing phenomenon of said DEF based on said determined DEF level; and

a DEF state determination means 103 to determine said state of said DEF based on said detected sloshing phenomenon.

3. The method as claimed in claim 1, wherein said detection of said DEF level is done after a pre determined interval of time.

4. The method as claimed in claim 1, wherein said state of said DEF is a frozen state when said sloshing effect of said DEF is not detected.

5. The method as claimed in claim 1, wherein said state of said DEF is a liquid state when said sloshing effect of said DEF is detected. ,TagSPECI:FIELD OF THE INVENTION

[001] The invention relates to a method to determine a state of reducing agent in a reducing agent tank of a vehicle. More particularly, it relates to determining the state of the reducing agent based on a detected reducing agent level variation.

BACKGROUND OF THE INVENTION

[002] A selective catalytic reduction (SCR) system for a vehicle is used to reduce the amount of nitrogen oxides (NOx) in the engine's exhaust. The SCR system uses a reducing agent, for example, diesel exhaust fluid (DEF), to lower NOx concentration in the engine’s exhaust emissions. The DEF is in a liquid state at room temperature and at -11 degree Celsius the DEF freezes to a frozen state due to the nature of its composition. The freezing behavior of the DEF is taken care by installing coolant based heating element to reheat and get the DEF to liquid state for the dosing of the DEF to occur.

[003] The prior art, US patent application US 20130074590, discloses a method for determining the state of a reducing agent in a reducing agent tank. The reducing agent is used for exhaust gas after-treatment of exhaust gas generated by an internal combustion engine. To inform the control unit of an internal combustion engine regarding the quality of the reducing agent in the reducing agent tank the method includes determining and recording the filling and extracting volumes of the reducing agent from the reducing agent tank by a fill level sensor, determining and recording the temperature of the reducing agent in the reducing agent tank by at least one temperature sensor over the entire service life of the exhaust gas after-treatment unit, determining and recording the distribution velocity of ultrasonic waves in the reducing agent by an ultrasonic transmitter and ultrasonic receiver, determining the state of a reducing agent from the parameters.

SHORT DESCRIPTION OF THE DRAWING

[004] An exemplifying embodiment of the invention is explained in principle below with reference to the drawings. The drawings are,

[005] Figure 1 illustrates a device to determine a state of Diesel Exhaust Fluid (DEF) in a DEF tank of a vehicle in accordance with this invention.

[006] Figure 2 illustrates a flowchart of the method to determine a state of Diesel Exhaust Fluid (DEF) in a DEF tank of a vehicle in accordance with this invention.

DESCRIPTION OF THE INVENTION

[007] Figure 1 illustrates a device 100 to determine a state of Diesel Exhaust Fluid (DEF) in a DEF tank of a vehicle in accordance with this invention. The device 100 comprises a DEF level sensor 101 to determine a DEF level in the DEF tank; a sloshing detection means 102 to detect a sloshing phenomenon of the DEF based on the determined DEF level; and a DEF state determination means 103 to determine the state of the DEF based on the detected sloshing phenomenon.

[008] The DEF level sensor 101, for example, a discreet level sensor such as a 10 pin level sensor, an ultrasonic level sensor, etc., obtains an analog signal equivalent of the DEF level in the DEF tank. The detection of the DEF level is done after a pre determined interval of time. The DEF level sensor 101 passes the analog signal equivalent of the DEF level through an Analog to Digital Converter (ADC) to obtain a voltage equivalent value of the DEF level. The DEF level sensor 101 checks the voltage equivalent value of the DEF level for any signal range errors. Further, the DEF level sensor 101 obtains a transformed DEF level signal by converting the voltage equivalent value of the DEF level into a corresponding percentage value by referring to a lookup table.

[009] The sloshing detection means 102 receives the transformed DEF level signal from the DEF level sensor 101. The sloshing detection means 102 samples the transformed DEF level signal for a predefined interval of time and stores the sampled transformed DEF level signal in a volatile memory. The sloshing detection means 102 analyzes the stored DEF level signal for a DEF level variation based on a change in the frequency and amplitude of the transformed DEF level signal. The variation in the level of the DEF in the DEF tank due to the movement of the vehicle is called the sloshing phenomenon of DEF. The variation in the DEF level causes a variation in the transformed DEF level signal. Thus, by analyzing the stored DEF level signal for the DEF level variation, the sloshing detection means 102 detects a sloshing phenomenon of the DEF.

[0010] At temperatures above -11 degree Celsius, the DEF is in a liquid state. The sloshing detection means 102 detects a change in the values of the frequency and amplitude of the stored transformed DEF level signal at temperatures above -11 degree Celsius. The DEF freezes in the DEF tank when the temperature drops below -11 degree Celsius. When the DEF inside the DEF tank is frozen, there is no variation in the frequency and amplitude of the stored transformed DEF level signal. The sloshing detection means 102 does not detects a change in the values of the frequency and amplitude of the stored transformed DEF level signal when temperature drops -11 degree Celsius.

[0011] The DEF state determination means 103 determines the state of the DEF based on the detected sloshing phenomenon of the DEF. The state of the DEF is a frozen state when the sloshing effect of the DEF is not detected. The state of the DEF is a liquid state when the detected level variation is not zero. The state of the DEF is a liquid state when the sloshing effect of the DEF is detected. The DEF state determination means 103 thus determines the state of the DEF based on the detected DEF level variation. By detecting the state of the DEF based on the detected DEF level variation, the use of tank temperature sensors is eliminated.

[0012] Figure 2 illustrates a flowchart of the method to determine a state of DEF in the DEF tank of the vehicle in accordance with this invention. At step S1, the DEF level determination means 101 determines a DEF level in the DEF tank. At step S2, the sloshing detection means 102 detects a sloshing phenomenon of the DEF based on the determined DEF level. At step S3, the DEF state determination means 103 determines the state of the DEF based on the detected sloshing phenomenon.

[0013] It must be understood that the embodiments explained in the above detailed description in only illustrative and does not limit the scope of this invention. The scope of this invention is limited only by the scope of the claims. Many modification and changes in the embodiments aforementioned are envisaged and are within the scope of this invention.