Claims:We Claim:

1. A method (10) of stopping a diesel engine, the method comprising:
determining (105), by a control unit, if an ignition is in OFF state;
determining (110), by the control unit, if engine speed is greater than a predefined engine speed for a time period greater than a predefined time period; and
controlling (115), by the control unit, any one of an inlet throttle valve and an exhaust back pressure flap to stop the engine, based upon successful determination of a state of the ignition and the engine speed by the control unit.

2. The method (10) of stopping the diesel engine as claimed in claim 1, wherein the predefined engine speed is 1200 rpm and the predefined time period is 2 seconds.

3. A method (20) of stopping a diesel engine, the method comprising:
determining (205), by a control unit, if an ignition is in ON state;
determining (210), by the control unit, if an accelerator pedal position is at a predefined position;
determining (215), by the control unit, if a fuel injection quantity is at a predefined quantity;
determining (220), by the control unit, if frequency of brake application is at a predefined frequency;
determining (225), by the control unit, if vehicle velocity is less than a predefined velocity;
determining (230), by the control unit, if engine speed is greater than a predefined engine speed for a time period greater than a predefined time period;
determining (235), by the control unit, if a gear position is in NEUTRAL; and
controlling (240), by the control unit, any one of an inlet throttle valve and an exhaust back pressure flap to stop the engine, based upon successful determination of above by the control unit.

4. The method of stopping the diesel engine as claimed in claim 3, wherein the predefined position is 0%.

5. The method of stopping the diesel engine as claimed in claim 3, wherein the predefined quantity is 0mg/st.

6. The method of stopping the diesel engine as claimed in claim 3, wherein the predefined velocity is 3kmph.

7. The method of stopping the diesel engine as claimed in claim 3, wherein the predefined engine speed is 2800 rpm and the predefined time period is 2 seconds.

8. A control unit, the control unit adapted to:
determine if an ignition is in OFF state;
determine if an engine speed is greater than a predefined engine speed for a time period greater than a predefined time period; and
control any one of an inlet throttle valve and an exhaust back pressure flap to stop the engine, based upon successful determination of a state of the ignition and the engine speed

9. A control unit, the control unit adapted to:
determine if an ignition is in ON state;
determine if an accelerator pedal position is at a predefined position;
determine if a fuel injection quantity is at a predefined quantity;
determine if frequency of brake application is at a predefined frequency;
determine if vehicle velocity is less than a predefined velocity;
determine if engine speed is greater than a predefined engine speed for a time period greater than a predefined time period;
determine if a gear position is in NEUTRAL; and
control any one of an inlet throttle valve and an exhaust back pressure flap to stop the engine, based upon successful determination of above by the control unit.
, Description:FIELD OF THE INVENTION
This invention relates to a method of stopping a diesel engine and a control unit adapted for the same.

BACKGROUND OF THE INVENTION
Combustion of engine oil (non-diesel) results in engine speed going up, resulting in hazardous situation for the vehicle and the driver and passengers. A reduction of this phenomenon is desirable. US1968831 discloses a mechanism in an internal combustion engine for supplying fuel to the engine, control means for governing the quantity of fuel delivered by said mechanism for each working stroke of the engine and means providing for the admission of combustion air to the engine, said last named means operating under the influence of said control means to provide substantially unrestricted flow of air to the engine at high engine loads and including a valve having a spring load variable under the influence of said control means for throttling the flow of air at lower engine loads subject to variations in the quantity of fuel delivered for each such working stroke.

BRIEF DESCRIPTION OF DRAWINGS
Embodiments of this disclosure is explained in principle below with reference to the drawings. The drawings are:
FIGURE 1 shows steps of a first method of stopping a diesel engine; and
FIGURE 2 shows steps of a second method of stopping the diesel engine.

DETAILED DESCRIPTION
FIGURE 1 shows steps of a first method 10 of stopping a diesel engine. The method 10 comprises a first step 105 of determining by a control unit, if an ignition is on OFF state, a second step 110 of determining by the control unit, if the engine speed is greater than a predefined engine speed for a time period greater than a predefined time period and a third step 115 of controlling by the control unit, any one of an inlet throttle valve and an exhaust back pressure flap to stop the engine, based upon successful determination of a state of the ignition and the engine speed by the control unit. The predefined engine speed can be 1200 rpm or any other value and the predefined time period can be 2 seconds or any other value as well. In the step 110, with the exemplary values above, the engine speed has to be greater than 1200 rpm for a time period greater than 2 seconds.
FIGURE 2 shows steps of a second method 20 for stopping a diesel engine. The method 20 comprises a first step 205 of determining by a control unit if an ignition is in ON state, a second step 210 of determining by the control unit, if an accelerator pedal position is at a predefined position, a third step 215 of determining by the control unit, if a fuel injection quantity is at a predefined quantity, a fourth step 220 of determining by the control unit, if frequency of brake application is at a predefined frequency, a fifth step 225 of determining by the control unit, if vehicle velocity is less than a predefined velocity, a sixth step 230 of determining by the control unit, if engine speed is greater than a predefined engine speed for a time period greater than a predefined time period, a seventh step 235 of determining by the control unit, if a gear position is in NEUTRAL and an eighth step 240 of controlling by the control unit, any one of an inlet throttle valve and an exhaust back pressure flap to stop the engine, based upon successful determination of above by the control unit. In the step 210, the predefined position can be 0%. In the step 215, the predefined quantity can be 0 mg/st. In the step 225, the predefined velocity can be 3 kmph. In the step 230, the predefined engine speed can be 2800 rpm and the predefined time period can be 2 seconds.
The control unit (not shown in drawings) mentioned above can be an electronic control unit (ECU) or any similar processor or controller implemented and used in both passenger vehicles and commercial vehicles. The control unit operates or works the methods 10 and 20 described above. The control unit in the first adaptation, determines if an ignition is in OFF state, determines if an engine speed is greater than a predefined engine speed for a time period greater than a predefined time period and controls any one of an inlet throttle valve and an exhaust back pressure flap to stop the engine, based upon successful determination of a state of the ignition and the engine speed.
The control unit in the second adaptation, determines if an ignition is in ON state, determines if an accelerator pedal position is at a predefined position, determines if a fuel injection quantity is at a predefined quantity, determines if frequency of brake application is at a predefined frequency, determines if vehicle velocity is less than a predefined velocity, determines if engine speed is greater than a predefined engine speed for a time period greater than a predefined time period, determine if a gear position is in NEUTRAL and control any one of an inlet throttle valve and an exhaust back pressure flap to stop the engine, based upon successful determination of above by the control unit.
The first adaptation of the control unit is equivalent to the method 10. The second adaptation of the control unit is equivalent to the method 20. The control unit can receive information on the status of the ignition, accelerator pedal position, fuel injection quantity, brake application frequency, vehicle velocity, engine speed and gear position, which is commonly understood by a person skilled in the art. The determination of the time period by the control unit is enabled by a clock in the control unit.
In the method 10, if the ignition is in an OFF state and if the engine speed is greater than the predefined engine speed, then it means that the engine is running on engine oil and not diesel and therefore the engine needs to be stopped. The control unit then controls any one of the inlet throttle valve or the exhaust back pressure flap to stop the engine. Closing the inlet throttle valve cuts off air supply to the engine, because of which combustion of the oil is disrupted which shuts the engine down. Closing the exhaust back pressure flap in the exhaust system creates a pressure increase in the engine, which disrupts the combustion in the cylinder, thereby shutting the engine down.
In the method 20, similarly, successful determination of all specified conditions mean that the engine is running on engine oil and not diesel and therefore the engine needs to be stopped. The control unit then controls either the inlet throttle valve or the exhaust back pressure flap to stop the engine. Successful determination, in this context, refers to satisfying the condition. For example, successful determination if the ignition is in an ON state means finding by the control unit if the ignition is in an ON state. If the control unit finds that the ignition is in the OFF state, then it is unsuccessful determination by the control unit with respect to the method 20. Hence, if all the conditions in the method 20 is satisfied or successfully determined, then the control unit actuates either the inlet throttle valve or the exhaust back pressure flap. For example, for both the method 10 and method 20, generally in passenger cars, only the inlet throttle valve is actuated, whereas in commercial vehicles, either the inlet throttle valve or the exhaust back pressure flap is actuated.
In some cases, the method 20 can have a prerequisite, but in some cases method 20 is independent. The steps in the prerequisite condition 30 for method 20 are as follows: a first step 305 of determining by the control unit if the ignition is in ON state, a second step 310 of determining by the control unit, if the accelerator pedal position is at a predefined position, a third step 315 of determining by the control unit, if vehicle velocity is less than a predefined velocity, a fourth step 320 of determining by the control unit, a rate of increase of engine speed and monitoring of oscillation and uncontrolled combustion, a fifth step 325 of determining by the control unit, if a gear position is above 2, a sixth step 330 of determining by the control unit, whether a clutch is engaged and a seventh step 335 of determining by the control unit, whether the brake is engaged. For example, in the prerequisite condition 30, the predefined position of the accelerator pedal position can be 0% and the predefined velocity can be 10 kmph.
By this way, the combustion of engine oil is reduced, thereby mitigating the harmful or disadvantageous effects of the same. The advantage is that, no new components are required and this can be effected with the existing components itself.
It must be understood that the embodiments explained in the above detailed description is only illustrative and does not limit the scope of this invention. Any modification in the embodiments are envisaged and form a part of this invention. The scope of this invention is limited only by the claims.