Cranking capability estimation for a vehicular starting system
View Patent ↗A method is provided for determining a cranking capability of a starting system for an internal combustion engine. An average power output of a battery is determined for the starting system during a start engine cranking interval. A temperature of the starting system is determined at an initiation of the start engine cranking interval. A predetermined average power output capability for a battery having a full state of charge at the determined temperature is looked up. A predetermined minimum average power output required of the battery for starting the respective engine at the determined temperature is looked up. A state of function based on the determined average power outputs is determined. The cranking capability of the starting system is identified in response to the determined state of function.
1. A method of determining a cranking capability of a starting system for an internal combustion engine, the method comprising the steps of:
(a) determining an average power output of a battery for the starting system during a start engine cranking interval;
(b) determining a temperature of the starting system at an initiation of the start engine cranking interval;
(c) looking up a predetermined average power output capability for a battery having a full state of charge at the determined temperature;
(d) looking up a predetermined minimum average power output required of the battery for starting the respective engine at the determined temperature;
(e) determining a state of function based on the average power output of steps (a), (c), and (d); and
(f) identifying the cranking capability of the starting system in response to the determined state of function.
2. The method of claim 1 wherein step (e) further comprises the steps of:
determining a difference between the average power outputs determined in steps (a) and (d);
determining a difference between the average power outputs determined in steps (c) and (d); and
calculating a ratio between the determined differences.
3. The method of claim 1 further comprising the step of determining if a starter motor deficiency is present, wherein the state of function is identified as a state of function for the starting system if a starter motor deficiency is present.
4. The method of claim 3 wherein the state of function is identified as a state of function for the battery if no starter motor deficiency is present.
5. The method of claim 1 wherein the step of identifying the cranking capability includes actuating an indicator to a driver of the vehicle for identifying a weakened starting system.
6. A method of determining a cranking capability of a starting system, the method comprising the steps of:
(a) detecting an ignition start operation;
(b) determining a temperature of the starting system at the initiation of the ignition start;
(c) measuring a battery voltage and a current during a predetermined interval of the ignition start;
(d) determining an actual average power output value of the battery during the predetermined interval;
(e) determining an average power output capability for a battery having a full state of charge at the determined temperature;
(f) determining a minimum average power output value required of the battery for starting the respective engine at the determined temperature; and
(g) calculating a state of function value of the starting system as a function of the average power output values determined in steps (d), (e), and (f).
7. The method of claim 6 wherein the step of identifying the cranking capability of the starting system further comprises comparing the calculated state of function value determined in step (g) to a state of function threshold value and actuating a warning signal to a driver of the vehicle for identifying a weakened starting system in response to the determined state of function value being less than the state of function threshold value.
8. The method of claim 6 further comprising the steps of:
determining whether a cranking device for cranking the engine is deteriorated;
identifying the determined state of function value as a starting system state of function value in response to a determination that the cranking device is deteriorated, otherwise, outputting the state of function value as a battery state of function value.
9. The method of claim 6 wherein the state of function is represented by the following formula:
SOF
=
P
_
b
-
P
_
b
_
lim
P
_
b
_
new
-
P
_
b
_
lim
×
100
%
where P b is the average power output of the battery of the starting system, P b — new is the average power output of a battery having a full state of charge, and P b — lim is the minimum average power output required by the battery to crank the vehicle engine at the determined temperature.
10. The method of claim 6 wherein the minimum average power output value required of the battery is determined as a function of the efficiency of the starting system, the load drawn by the starting system, and the kinetic power output of the starting system.
11. The method of claim 6 wherein step (b) includes measuring the temperature of the battery.
12. The method of claim 6 wherein step (b) includes measuring the temperature of the starter motor.
13. The method of claim 6 wherein step (b) includes measuring the temperature of the engine.
14. The method of claim 6 wherein step (b) includes measuring the temperature of at least one of the battery, the starter motor, and the engine.
15. A starting performance indication system for a vehicle starting system, the vehicle starting system including an internal combustion engine, a cranking device for cranking the internal combustion engine, a coupling device for mechanically coupling the cranking device to the internal combustion engine, and an energy storage device for supplying power to the cranking device for energizing the cranking device, the starting performance indication system comprising:
at least one sensing device for determining a temperature of at least the energy storage device, the cranking device, and engine oil in the engine;
a voltage sensing device for sensing the voltage output from the energy storage device;
a current sensing device for sensing the current drawn by the cranking device;
a control module having a starting system monitoring and prognosis routine for determining a state of function of the starting system, wherein the control module determines an average power output of the battery during the predetermined interval during engine cranking, an average power output for a battery having a full state of charge for starting the internal combustion engine at the determined temperature, and a minimum average power output value required of the battery for starting the internal combustion engine at the determined temperature;
wherein the control module estimates the cranking capability of the starting system as function of the average power output of the battery during the predetermined interval during engine cranking, as a function of the average power output for a battery having a full state of charge, and as a function of the minimum average power output value required of the battery for starting the internal combustion engine.
16. The starting performance indication system of claim 15 further comprising a warning indicator for providing a cranking capability warning to the driver of the vehicle in response to the control module determining the state of function being a weakened state.
17. The starting performance indication system of claim 15 wherein the control module estimates the cranking capability of the starting system by comparing a calculated state of function to a state of function threshold value, the calculated state of function value being determined by the following formula:
SOF
=
P
_
b
-
P
_
b
_
lim
P
_
b
_
new
-
P
_
b
_
lim
×
100
%
where P b is the average power output of the battery over a predetermined time interval, P b — new is an average power output of a new battery have a full SOC that successfully cranks the engine, and P b — lim is a minimum average power output value required of the battery to successfully crank the engine over the predetermined for the respective starting system.
18. The starting performance indication system of claim 15 wherein the control module includes a battery control module.