Description:Complete Specification:

The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention is related to a control unit for detecting a working state of an air filter in a vehicle and a method thereof.

Background of the invention
[0002] Vehicles typically have an air filter that cleans outside air before the air is ingested into the engine to mix with fuel before combustion. Over time, the air filter becomes clogged with dust, dirt, and other debris, in particular if the vehicle travels on dirt roads. Symptoms of a dirty/clogged air filter may vary but often include a noticeable decrease in gas mileage. Other symptoms include potential ignition problems caused by fouled spark plugs. A dirty air filter prevents the necessary volume of clean air from reaching the engine, which affects the emission control systems of the vehicle, reducing air flow and causing a too rich air-fuel mixture which can foul the spark plugs. In addition, a too rich fuel mixture increases engine deposits.

[0003] A US10774760 discloses systems and methods for detecting a clogged intake air filter in a turbocharged engine system are provided. In one example a method for an engine coupled to an air filter and to a fuel tank includes indicating air filter clogging responsive to a measured fuel tank pressure during boosted engine operation. In this way, clogging of the air filter may be determined using existing engine system components.
Brief description of the accompanying drawings
[0004] Figure 1 illustrates a control unit for detecting a working state of an air filter in a vehicle, in accordance with an embodiment of the invention; and
[0005] Figure 2 illustrates a flowchart for a method for detecting a working state of the air filter in the vehicle in accordance with the present invention.

Detailed description of the embodiments
[0006] Figure 1 illustrates, in accordance with an embodiment of the invention. The control unit 10 measures a first pressure value in an intake manifold 14 of the vehicle 11, when an engine 15 is in an off condition and measures a second pressure value in the intake manifold 14 when the engine 15 is in an on condition. The control unit 10 further compares a difference value obtained from the first pressure value and the second pressure value with a first threshold value. The control unit 10 measures a third pressure value in the intake manifold 14 when the engine 15 is brought to the off condition. The control unit 10 then detects the working state of the air filter 12 based on a comparison between measured third pressure value and the first pressure value.

[0007] Further the details of the working of the different components of the control unit and the vehicle are explained. The control unit 10 is chosen from a group of control units comprising a microprocessor, a microcontroller, a digital circuit, an integrated chip and the like. The control unit 10 comprises a comparator 17 for comparing different pressure values both when the engine is in ON and off state. The control unit 10 further comprises a counter 18 for counting the number of iterations. The air filter 12 is positioned in the intake manifold 14. When the user of the vehicle 11 gives throttle for increasing the speed of the vehicle 11, the air from the surrounding atmosphere is drawn inside.

[0008] The air filter 12 filters out the impurities present in the intake air and is supplied to the engine. Wherein due to the filtering of the impurities will clog the filter 12 over a period of time. Due to this, the sufficient amount of air that is to be supplied to the engine 15 will not be obtained, thus damaging the engine components. In order to avoid this, the control unit 10 of the present invention detects the clog of the filter 12 well in advance and alerts the user of the vehicle 11. The alert is generated on a dashboard of the vehicle 11 in any one of the forms like a light, buzzer, an alarm, a sound and the like as known to a person skilled in the art, upon detecting a clog in the air filter 12.

[0009] A method for detecting a working state of an air filter 12 in a vehicle 10 in according to one embodiment of the invention. In step S1, a first pressure value is measured in an intake manifold 14 of the vehicle 10, when an engine 15 is in an off condition. In step S2, a second pressure value is measured in the intake manifold 14 when the engine is in an on condition. In step S3, a difference value is obtained from the first pressure value and the second pressure value and is compared with a first threshold value. In step S4, a third pressure value is measured in the intake manifold 14 when the engine 15 is brought to the off condition. In step S5, the working state of the air filter 12 is detected based on a comparison between the measured third pressure value and the first pressure value.

[0010] The method of detecting the clog in the air filter 12 is explained in detail. The control unit 10 measures the pressure of the air in the intake manifold 14 when the engine 15 is in OFF condition and it is referred as first pressure value. When the engine 15 is OFF, the pressure inside the manifold 14 is same as ambient. As mentioned above, this pressure value is measured and stored in a memory of the control unit 10 as soon as the ignition is switched. When the engine 15 is switched on and the vehicle 11 is in full throttle condition, the control unit 10 checks for the following conditions to be satisfied. First condition being whether the engine 15 has achieved full load ie. a current engine speed is more than a predefined threshold value and second condition being the throttle value (i.e.., accelerator pedal percentage) is more than a predefined percentage value.

[0011] If both these conditions are met, the control unit 10 again measures the pressure in the intake manifold 14. When the engine 15 is running at high speed and wide-open throttle, the manifold 14 pressure will be almost equal to the ambient pressure with a clean air filter 12. The second manifold pressure in this engine 15 operating condition, is compared with the first measured pressure value. Any decrease in manifold pressure compared to first pressure value in wide open throttle condition is an indication of a dirty air filter.

[0012] The difference between the first pressure value and the second pressure value is determined by the control unit 10 and is compared with the first threshold value. If the difference is more than the first threshold value, then the control unit 10 detects that there is a clog in the air filter 12.

[0013] In addition to the above-mentioned condition, the control unit 10 measures the third pressure value when the engine 15 is switched off again. After the engine 15 is switched OFF at the end of the drive cycle, manifold pressure is measured again and is stored as third pressure value. By considering the above-mentioned pressure values, the control unit 10 determines a variation in the first pressure value and the third pressure value. The counter in the control unit 10 increments by one, when it detects a large variation between the first pressured value and the third pressure value. For example, if the count in the counter is more than 3, then the control unit 10 detects a clog in the air filter 12.

[0014] If the control unit 12 detects a large variation between the first pressure value and the third pressure value for more than a predefined number of times (as obtained from the counter) and the difference of the first pressure value and the second pressure value is more than the predefined threshold value, then the control unit 10 detects a clog in the air filter 12. Otherwise, if the control unit 10 detects that there is very little variation between the first pressure value and the third pressure value and the difference between the first pressure value and the second pressure value is more than the first threshold value, then the control unit 10 indicates that the pressure difference is due to the change in the altitude of the vehicle 11.

[0015] Upon detecting the clog in the air filter 12 and the level of clog, the control unit 10 activates a limp home mode in the vehicle 11 for moving the vehicle to a safe area. The above-mentioned method is used to detect the clog in the air filter 12 in advance thus eliminating the damage to the engine components. The method provides a low-cost effective solution.

[0016] Embodiments explained in the description above are only illustrative and do not limit the scope of this invention. 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
, Claims:We Claim:
1. A control unit (10) for detecting a working state of an air filter (12) in a vehicle (11), said control unit (10) adapted to:
- measure a first pressure value in an intake manifold (14) of said vehicle (11), when an engine (15) is in an off condition;
- measure a second pressure value in said intake manifold (14) when said engine (15) is in an on condition;
- compare a difference value obtained from said first pressure value and said second pressure value with a first threshold value;
- measure a third pressure value in said intake manifold (14) when said engine (15) is brought to said off condition;
- detect said working state of said air filter (12) based on a comparison between measured third pressure value and said first pressure value.

2. The control unit (10) as claimed in claim 1, wherein said air filter (12) is positioned in said intake manifold (14) for filtering impurities entering said vehicle (11).

3. The control unit (10) as claimed in claim 1, wherein said control unit (10) detect a clog in said air filter (12), when said difference value obtained from said first pressure value and said second pressure value is greater than said first threshold value.

4. The control unit (10) as claimed in claim 1, wherein said control unit (10) detect said clog in said air filter (12), when a difference between said first pressure value is varied from said third pressure value for more than a predefined number of iterations.

5. The control unit (10) as claimed in claims 3 & 4, wherein said control unit (10) detects said clog in said air filter (12), when above two conditions are satisfied.

6. The control unit (10) as claimed in claims 3 & 4, wherein said control unit (10) detects a change in altitude of said vehicle (11), when only one condition is satisfied.

7. The control unit (10) as claimed in claim 1, wherein said control unit (10) activates a limp home mode based on said detected clog level of said air filter (12).

8. The control unit (10) as claimed in claim 1, wherein said control unit (10) generates an alert upon detecting a clog in said air filter (12).

9. A method for detecting a working state of an air filter (12) in a vehicle (11), said method comprising steps of:
- measuring a first pressure value in an intake manifold (14) of said vehicle (11), when an engine (15) is in an off condition;
- measuring a second pressure value in said intake manifold (14) when said engine (15) is in an on condition;
- comparing a difference value obtained from said first pressure value and said second pressure value with a first threshold value;
- measuring a third pressure value in said intake manifold (14) when said engine (15) is brought to said off condition;
- detecting said working state of said air filter (12) based on a comparison between measured third pressure value and said first pressure value.