APPARATUS FOR ESTIMATING CHARGED STATE OF ON-VEHICLE BATTERY

• US 20090115419A1
• Filed: 11/06/2008
• Published: 05/07/2009
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: DENSO Corporation, Nippon Soken, Inc.
• Original Assignee: DENSO Corporation, Nippon Soken, Inc.
• Inventors: UEDA, Kenzi, Yamamoto, Naoki
• Granted Patent: US 8,536,872 B2
• Time in Patent Office: Days
• US Class Current: 324/430
• CPC Class Codes: F02N 11/0825 related to prevention of engine restart failure, e.g. disabling automatic stop at low battery state
• CPC Class Codes: F02N 2200/063 Battery voltage
• CPC Class Codes: F02N 2200/064 Battery temperature
• CPC Class Codes: F02N 2250/02 Battery voltage drop at start, e.g. drops causing ECU reset
• CPC Class Codes: F02N 2300/2006 using prediction of future conditions
• CPC Class Codes: G01R 31/007 using microprocessors or computers
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

An apparatus is provided to estimate a charged state of a vehicle provided with an internal combustion engine having a crankshaft, a starter that initially rotates the crankshaft when the engine is started, and a battery that powers the starter. The apparatus comprises a detection device and an acquisition device. The detection device detects a voltage of the battery and a discharge current from the battery for a period of time over time instants before and after starting the engine. The acquisition device acquires information indicative of an amount of the discharge current from the battery when the detected voltage of the battery becomes a minimum due to starting the engine.

Claims

1. An apparatus for estimating a charged state of a vehicle provided with an internal combustion engine having a crankshaft, a starter that initially rotates the crankshaft when the engine is started, and a battery that powers the starter, comprising

detection means for detecting a voltage of the battery and a discharge current from the battery for a period of time ranging time instants before and after starting the engine;

acquisition means for acquiring information indicative of an amount of the discharge current from the battery when the detected voltage of the battery becomes a minimum due to starting the engine.

2. The apparatus of claim 1, wherein the acquisition means comprises discharge current estimating means for estimating a difference between the amount of the discharge current before starting the engine and the amount of the discharge current when the detected voltage becomes the minimum due to starting the engine, based on the detected voltage and current, the difference being estimated as a maximum discharge current amount of the battery necessary for starting the engine.

3. The apparatus of claim 2, wherein the discharge current estimating means includes means for estimating, based on the detected voltage and current, an internal resistance of the battery in a period of time lasting until the voltage of the battery reaches a minimum voltage due to starting the engine, and means for estimating the maximum discharge current amount in accordance with the estimated internal resistance of the battery.

4. The apparatus of claim 2, wherein

the detected voltage and current is composed of a plurality of pairs of detected voltage and current and

the discharge current estimating means includes

means for calculating a difference between the detected voltage given before starting the starter and a minimum value of the detected voltage which appears in response to starting the starter;

means for calculating a maximum drop amount of the voltage of the battery based on the difference of the voltage;

means for estimating an internal resistance of the battery based on the plurality of pairs of detected voltage and current; and

means for estimating the maximum discharge current amount based on the estimated internal resistance and the calculated maximum drop amount.

5. The apparatus of claim 2, wherein

the detected voltage and current is composed of a plurality of pairs of detected voltage and current and

the discharge current estimating means includes

means for estimating an internal resistance of the battery based on, of the plurality of pairs of detected voltage and current, a plurality of pairs of voltage and current detected after the voltage of the battery decreased down to a minimum voltage thereof due to starting the starter;

means for estimating a difference between values of an open-end voltage of the batter appearing before and after starting the starter based on the estimated internal resistance and the detected voltage and current; and

means for estimating an internal resistance of the battery appearing when the voltage of the battery decreased down to a minimum voltage thereof based on the estimated difference of the open-end voltage and the estimated internal resistance.

6. The apparatus of claim 2, wherein

the detected voltage and current is composed of a plurality of pairs of detected voltage and current and

the discharge current estimating means includes

means for estimating an internal resistance of the battery based on a plurality of pairs of voltage and current which are detected in a predetermined period of time followed by an event where the voltage of the battery decreases down to a minimum voltage due to starting the starter,

means for calculating a difference between the detected voltage given before starting the starter and a minimum value of the detected voltage which appears in response to starting the starter,

means for calculating a maximum drop amount of the voltage of the battery based on the difference of the voltage, and

means for estimating the maximum discharge current amount based on the calculated maximum drop amount and the calculated internal resistance,

wherein the predetermined period of time is set to a period of time which gives an assumption that the internal resistance of the battery approximates a value appearing in a period of time during which the voltage of the battery decreases down to a minimum voltage due to starting the starter.

7. The apparatus of claim 2, wherein

the detected voltage and current is composed of a plurality of pairs of detected voltage and current and

the discharge current estimating means includes

means for estimating an internal resistance of the battery based on a plurality of pairs of voltage and current which are detected in a predetermined period of time followed by an event where the voltage of the battery decreases down to a minimum voltage due to starting the starter, and

means for estimating the maximum discharge current amount based on the minimum voltage of the battery and the estimated internal resistance,

wherein the predetermined period of time is set to a period of time which gives an assumption that the internal resistance of the battery approximates a value given by a gradient of an arithmetic line defined an event where the voltage of the battery decreases down to a minimum voltage due to starting the starter and an event the voltage of the battery recovers up to a specific value.

8. The apparatus of claim 2, further comprising

prediction means for predicting a minimum value of the voltage of the battery which is to be caused when the starter is activated for starting the engine at present, on the basis of the estimated maximum discharge current amount and the detected voltage of the battery.

9. The apparatus of claim 8, wherein

the discharge current estimating means comprises memory means previously storing the estimated maximum discharge current amount, one by one correspondence, every divided range of at least one of a discharge capacity of the battery and temperature of the battery, and

the prediction means predicts the minimum value of the voltage based on the maximum discharge current amount corresponding to a specified range of the divided ranges, the specified range corresponding to a current state of the at least one of the discharge capacity and the temperature.

10. The apparatus of claim 3, wherein

the detected voltage and current is composed of a plurality of pairs of detected voltage and current and

the discharge current estimating means includes

means for calculating a difference between the detected voltage given before starting the starter and a minimum value of the detected voltage which appears in response to starting the starter;

means for calculating a maximum drop amount of the voltage of the battery based on the difference of the voltage;

means for estimating an internal resistance of the battery based on the plurality of pairs of detected voltage and current; and

means for estimating the maximum discharge current amount based on the estimated internal resistance and the calculated maximum drop amount.

11. The apparatus of claim 3, wherein

the detected voltage and current is composed of a plurality of pairs of detected voltage and current and

the discharge current estimating means includes

means for estimating an internal resistance of the battery based on, of the plurality of pairs of detected voltage and current, a plurality of pairs of voltage and current detected after the voltage of the battery decreased down to a minimum voltage thereof due to starting the starter;

means for estimating a difference between values of an open-end voltage of the batter appearing before and after starting the starter based on the estimated internal resistance and the detected voltage and current; and

means for estimating an internal resistance of the battery appearing when the voltage of the battery decreased down to a minimum voltage thereof based on the estimated difference of the open-end voltage and the estimated internal resistance.

12. The apparatus of claim 3, wherein

the detected voltage and current is composed of a plurality of so pairs of detected voltage and current and

the discharge current estimating means includes

means for estimating an internal resistance of the battery based on a plurality of pairs of voltage and current which are detected in a predetermined period of time followed by an event where the voltage of the battery decreases down to a minimum voltage due to starting the starter,

means for calculating a difference between the detected voltage given before starting the starter and a minimum value of the detected voltage which appears in response to starting the starter,

means for calculating a maximum drop amount of the voltage of the battery based on the difference of the voltage, and

means for estimating the maximum discharge current amount based on the calculated maximum drop amount and the calculated internal resistance,

wherein the predetermined period of time is set to a period of time which gives an assumption that the internal resistance of the battery approximates a value appearing in a period of time during which the voltage of the battery decreases down to a minimum voltage due to starting the starter.

13. The apparatus of claim 3, further comprising

prediction means for predicting a minimum value of the voltage of the battery which is to be caused when the starter is activated for starting the engine at present, on the basis of the estimated maximum discharge current amount and the detected voltage of the battery.

14. The apparatus of claim 13, wherein

the discharge current estimating means comprises memory means previously storing the estimated maximum discharge current amount, one by one correspondence, every divided range of at least one of a discharge capacity of the battery and temperature of the so battery, and

the prediction means predicts the minimum value of the voltage based on the maximum discharge current amount corresponding to a specified range of the divided ranges, the specified range corresponding to a current state of the at least one of the discharge capacity and the temperature.

15. The apparatus of claim 1, further comprising

prediction means for predicting a minimum value of the voltage of the battery which is to be caused when the starter is activated for starting the engine at present, on the basis of the estimated maximum discharge current amount and the detected voltage of the battery.

16. The apparatus of claim 15, wherein

the discharge current estimating means comprises memory means previously storing the estimated maximum discharge current amount, one by one correspondence, every divided range of at least one of a discharge capacity of the battery and temperature of the battery, and

the prediction means predicts the minimum value of the voltage based on the maximum discharge current amount corresponding to a specified range of the divided ranges, the specified range corresponding to a current state of the at least one of the discharge capacity and the temperature.

17. An automatic stop and start control apparatus, comprising

an apparatus for estimating a charged state of a vehicle provided with an internal combustion engine having a crankshaft, a starter that initially rotates the crankshaft when the engine is started, and a battery that powers the starter, the estimating apparatus comprising

detection means for detecting a voltage of the battery

and a discharge current from the battery for a period of time over time instants before and after starting the engine;

acquisition means for acquiring information indicative of an amount of the discharge current from the battery when the detected voltage of the battery becomes a minimum due to starting the engine, wherein the acquisition means comprises discharge current estimating means for estimating a difference between the amount of the discharge current before starting the engine and the amount of the discharge current when the detected voltage becomes the minimum due to starting the engine, based on the detected voltage and current, the difference being estimated as a maximum discharge current amount of the battery necessary for starting the engine; and

prediction means for predicting a minimum value of the voltage of the battery which is to be caused when the starter is activated for starting the engine at present, on the basis of the estimated maximum discharge current amount and the detected voltage of the battery; and

means for performing at least one of an automatic stop process and an automatic start process based on the minimum value of the voltage of the battery predicted by the prediction means.

18. The apparatus of claim 17, wherein

the discharge current estimating means comprises memory means previously storing the estimated maximum discharge current amount, one by one correspondence, every divided range of at least one of a discharge capacity of the battery and temperature of the battery, and

the prediction means predicts the minimum value of the voltage based on the maximum discharge current amount corresponding to a specified range of the divided ranges, the specified range corresponding to a current state of the at least one of the discharge capacity and the temperature.

19. An apparatus for estimating a charged state of a vehicle provided with an internal combustion engine having a crankshaft, a starter that initially rotates the crankshaft when the engine is started, and a battery that powers the starter, comprising

a detection unit that detects a voltage of the battery and a discharge current from the battery for a period of time over time instants before and after starting the engine;

an acquisition unit that acquires information indicative of an amount of the discharge current from the battery when the detected voltage of the battery becomes a minimum due to starting the engine.

20. The apparatus of claim 19, wherein the acquisition unit comprises a discharge current estimating device that estimates a difference between the amount of the discharge current before starting the engine and the amount of the discharge current when the detected voltage becomes the minimum due to starting the engine, based on the detected voltage and current, the difference being estimated as a maximum discharge current amount of the battery necessary for starting the engine.